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Motor oil

2011-02-15T14:02:54Z

Fluonova:

{{Refimprove|date=March 2009}}
{{Original research|date=September 2010}}
[[File:Motor oil.JPG|thumb|250px|A sample of motor oil]]

'''Motor oil''', or '''engine oil''', is an [[oil]] used for [[lubrication]] of various [[internal combustion engine]]s. While the main function is to lubricate [[moving parts]], motor oil also cleans, inhibits [[corrosion]], improves [[sealing]], and [[engine cooling|cools the engine]] by carrying [[heat]] away from moving parts.<ref>Klamman, Dieter, ''Lubricants and Related Products'', Verlag Chemie, 1984, ISBN 0-89573-177-0</ref>

Motor oils are derived from [[Petroleum|petroleum-based]] and non-petroleum-synthesized chemical compounds. Motor oils today are mainly blended by using base oils composed of [[hydrocarbon]]s, polyalphaolefins (PAO), and polyinternal olefins<ref>G. Corsico, L. Mattei, A. Roselli and C. Gommellini, Poly(internal olefins)- Synthetic Lubricants and high-performance functional fluids,, Marcel Dekker, 1999,Chapter 2, p. 53-62, ISBN 0-8247-0194-1</ref> (PIO), thus [[organic compounds]] consisting entirely of [[carbon]] and [[hydrogen]]. The base oils of some high-performance motor oils contain up to 20 wt.-% of esters.<ref>R.H. Schlosberg, J.W. Chu, G.A. Knudsen, E.N. Suciu and H.S. Aldrich, High stability esters for synthetic lubricant applications, Lubrication Engineering, February 2001, p. 21-26motor oil is bad for the environment.
</ref>

==Use==
Motor oil is a [[lubricant]] used in internal combustion engines. These include [[motor vehicles|motor]] or [[road vehicle|road]] vehicles such as [[car]]s and [[motorcycle]]s, heavier vehicles such as [[bus]]es and [[Large Goods Vehicle|commercial vehicles]], non-road vehicles such as [[Kart racing|go-karts]], [[snowmobiles]], [[boats]] (fixed engine installations and outboards), [[lawn mowers]], large agricultural and construction equipment, [[locomotives]] and [[aircraft]], and static engines such as [[electrical generator]]s. In engines, there are parts which move against each other causing [[friction]] which wastes otherwise useful [[motive power|power]] by converting the energy to heat. Contact between moving surfaces also [[wear]]s away those parts, which could lead to lower efficiency and degradation of the engine. This increases fuel consumption, decreases power output and can, in extreme cases lead to engine failure.

Lubricating oil creates a separating film between surfaces of adjacent moving parts to minimize direct contact between them, decreasing heat caused by friction and reducing wear, thus protecting the engine. In use, motor oil transfers heat through [[convection]] as it flows through the engine by means of air flow over the surface of the oil pan, an oil cooler and through the build up of oil [[gas]]es evacuated by the [[PCV valve|Positive Crankcase Ventilation]] (PCV) system.

In petrol (gasoline) engines, the top [[piston ring]] can expose the motor oil to temperatures of 320 °F (160 °C). In diesel engines the top ring can expose the oil to temperatures over 600 °F (315 °C). Motor oils with higher [[viscosity]] indices thin less at these higher temperatures.

Coating metal parts with [[oil]] also keeps them from being exposed to [[oxygen]], inhibiting [[oxidation]] at elevated [[operating temperature]]s preventing [[rust]] or [[corrosion]]. [[Corrosion inhibitor]]s may also be added to the motor oil. Many motor oils also have [[detergent]]s and [[dispersant]]s added to help keep the engine clean and minimize [[oil sludge]] build-up. The oil is able to trap soot from combustion in itself, rather than leaving it deposited on the internal surfaces. It is a combination of this, and some singeing that turns used oil black after some running.

Rubbing of metal engine parts inevitably produces some microscopic metallic particles from the wearing of the surfaces. Such particles could circulate in the oil and grind against moving parts, causing wear. Because particles accumulate in the oil, it is typically circulated through an [[oil filter]] to remove harmful particles. An [[oil pump]], a vane or [[gear pump]] powered by the engine, pumps the oil throughout the engine, including the oil filter. Oil filters can be a ''full flow'' or ''bypass'' type.

In the [[crankcase]] of a vehicle engine, motor oil lubricates rotating or sliding surfaces between the [[crankshaft]] [[journal bearings]] (main bearings and big-end bearings), and [[connecting rod|rods]] connecting the [[pistons]] to the crankshaft. The oil collects in an [[oil pan]], or [[sump]], at the bottom of the crankcase. In some small engines such as lawn mower engines, dippers on the bottoms of connecting rods dip into the oil at the bottom and splash it around the crankcase as needed to lubricate parts inside. In modern vehicle engines, the oil pump takes oil from the oil pan and sends it through the oil filter into oil galleries, from which the oil lubricates the main bearings holding the crankshaft up at the main journals and camshaft bearings operating the valves. In typical modern vehicles, oil pressure-fed from the oil galleries to the main bearings enters holes in the main journals of the crankshaft. From these holes in the main journals, the oil moves through passageways inside the crankshaft to exit holes in the rod journals to lubricate the rod bearings and connecting rods. Some simpler designs relied on these rapidly moving parts to splash and lubricate the contacting surfaces between the piston rings and interior surfaces of the cylinders. However, in modern designs, there are also passageways through the rods which carry oil from the rod bearings to the rod-piston connections and lubricate the contacting surfaces between the piston rings and interior surfaces of the [[Cylinder (engine)|cylinder]]s. This oil film also serves as a seal between the piston rings and cylinder walls to separate the [[combustion chamber]] in the [[cylinder head]] from the crankcase. The oil then drips back down into the oil pan.<ref>[http://auto.howstuffworks.com/engine.htm "How Car Engines Work"]</ref><ref>[http://www.tpub.com/content/construction/14264/css/14264_242.htm "Types of Lubricating Systems"]</ref> Motor Oil is also use for engine cleaning.

==Non-vehicle motor oils==
An example is lubricating oil for [[4-stroke]] or 4-cycle internal combustion engines such as those used in portable electricity generators and "walk behind" [[lawn mower]]s. Another example is [[2-stroke oil]] for lubrication of [[2-stroke]] or 2-cycle internal combustion engines found in [[Scooter (motorcycle)|motor scooters]], [[snow blower]]s, [[chain saw]]s, model airplanes, gasoline powered gardening equipment like hedge trimmers, leaf blowers and soil cultivators. Often, these motors are not exposed to as wide service temperature ranges as in vehicles, so these oils may be single viscosity oils.

In older 2-stroke engines, the oil may be pre-mixed with the [[gasoline]] or fuel, often in a rich gasoline:oil ratio of 25:1, 40:1 or 50:1, and burned in use along with the gasoline. Modern [[two-stroke engine]]s used in boats and motorcycles, will have a more economical oil injection system rather than oil pre-mixed into the gasoline. The oil properties will vary according to the individual needs of these devices. Non-smoking 2-cycle oils are composed of esters or polyglycols. Environmental legislations for leisure marine applications, especially in Europe, enhanced the use of ester-based two cycle oils.

==Properties==
Most motor oils are made from a heavier, thicker [[petroleum]] [[hydrocarbon]] base stock derived from [[crude oil]], with additives to improve certain properties. The bulk of a typical motor oil consists of [[hydrocarbon]]s with between 18 and 34 [[carbon]] [[atom]]s per [[molecule]].<ref>Chris Collins (2007), “Implementing Phytoremediation of Petroleum Hydrocarbons, ''Methods in Biotechnology'''' 23'':99-108. Humana Press. ISBN 1588295419.</ref> One of the most important properties of motor oil in maintaining a lubricating film between moving parts is its [[viscosity]]. The viscosity of a liquid can be thought of as its "thickness" or a measure of its resistance to flow. The viscosity must be high enough to maintain a lubricating film, but low enough that the oil can flow around the engine parts under all conditions. The [[viscosity index]] is a measure of how much the oil's viscosity changes as temperature changes. A higher viscosity index indicates the viscosity changes less with temperature than a lower viscosity index.

Motor oil must be able to flow adequately at the lowest temperature it is expected to experience in order to minimize metal to metal contact between moving parts upon starting up the engine. The ''pour point'' defined first this property of motor oil, as defined by ASTM D97 as "...an index of the lowest temperature of its utility..." for a given application,<ref>http://www.astm.org/Standards/D97.htm</ref> but the "cold cranking simulator" (CCS, see ASTM D5293-08) and "Mini-Rotary Viscometer" (MRV, see ASTM D3829-02(2007), ASTM D4684-08) are today the properties required in motor oil specs and define the SAE classifications.

Oil is largely composed of hydrocarbons which can burn if ignited. Still another important property of motor oil is its [[flash point]], the lowest temperature at which the oil gives off vapors which can ignite. It is dangerous for the oil in a motor to ignite and burn, so a high flash point is desirable. At a [[Oil refinery|petroleum refinery]], [[fractional distillation]] separates a motor oil fraction from other crude oil fractions, removing the more volatile components, and therefore increasing the oil's flash point (reducing its tendency to burn).

Another manipulated property of motor oil is its [[Total Base Number]] (TBN), which is a measurement of the reserve [[alkalinity]] of an oil, meaning its ability to neutralize acids. The resulting quantity is determined as mg KOH/ (gram of lubricant). Analogously, [[Total Acid Number]] (TAN) is the measure of a lubricant's [[acidity]]. Other tests include [[zinc]], [[phosphorus]], or [[sulfur]] content, and testing for excessive [[foam]]ing.

The [[NOACK volatility]] (ASTM D-5800) Test determines the physical evaporation loss of lubricants in high temperature service. A maximum of 15% evaporation loss is allowable to meet API SL and ILSAC GF-3 specifications. Some automotive OEM oil specifications require lower than 10%.

==Grades==
[[File:Motor Oils.jpg|thumb|Range of motor oils on display in Kuwait]]

The [[Society of Automotive Engineers]] (SAE) has established a numerical code system for grading motor oils according to their viscosity characteristics. SAE viscosity gradings include the following, from low to high viscosity: 0, 5, 10, 15, 20, 25, 30, 40, 50 or 60. The numbers 0, 5, 10, 15 and 25 are suffixed with the letter W, designating their "winter" (not "weight") or cold-start viscosity, at lower temperature. The number 20 comes with or without a W, depending on whether it is being used to denote a cold or hot viscosity grade. The document SAE J300 defines the viscometrics related to these grades.

Kinematic viscosity is graded by measuring the time it takes for a standard amount of oil to flow through a standard orifice, at standard temperatures. The longer it takes, the higher the viscosity and thus higher SAE code.

Note that the SAE has a separate viscosity rating system for gear, axle, and manual transmission oils, SAE J306, which should not be confused with engine oil viscosity. The higher numbers of a gear oil (eg 75W-140) do not mean that it has higher viscosity than an engine oil.

===Single-grade===
A single-grade engine oil, as defined by SAE J300, cannot use a polymeric [[Viscosity index|Viscosity Index Improver]] (also referred to as Viscosity Modifier) additive. SAE J300 has established eleven viscosity grades, of which six are considered Winter-grades and given a W designation. The 11 viscosity grades are 0W, 5W, 10W, 15W, 20W, 25W, 20, 30, 40, 50, and 60. These numbers are often referred to as the 'weight' of a motor oil.

For single winter grade oils, the dynamic viscosity is measured at different cold temperatures, specified in J300 depending on the viscosity grade, in units of mPa·s or the equivalent older non-SI units, [[Poise|centipoise]] (abbreviated cP), using two different test methods. They are the Cold Cranking Simulator (ASTM D5293) and the Mini-Rotary Viscometer (ASTM D4684). Based on the coldest temperature the oil passes at, that oil is graded as SAE viscosity grade 0W, 5W, 10W, 15W, 20W, or 25W. The lower the viscosity grade, the lower the temperature the oil can pass. For example, if an oil passes at the specifications for 10W and 5W, but fails for 0W, then that oil must be labeled as an SAE 5W. That oil cannot be labeled as either 0W or 10W.

For single non-winter grade oils, the kinematic viscosity is measured at a temperature of 100 °C (212 °F) in units of mm²/s or the equivalent older non-SI units, [[Stokes (unit)|centistokes]] (abbreviated cSt). Based on the range of viscosity the oil falls in at that temperature, the oil is graded as SAE viscosity grade 20, 30, 40, 50, or 60. In addition, for SAE grades 20, 30, and 40, a minimum viscosity measured at 150 °C (302 °F) and at a high-shear rate is also required. The higher the viscosity, the higher the SAE viscosity grade is.

For some applications, such as when the temperature ranges in use are not very wide, single-grade motor oil is satisfactory; for example, lawn mower engines, industrial applications, and vintage or [[classic car]]s.

===Multi-grade===
The temperature range the oil is exposed to in most vehicles can be wide, ranging from cold temperatures in the winter before the vehicle is started up, to hot operating temperatures when the vehicle is fully warmed up in hot summer weather. A specific oil will have high viscosity when cold and a lower viscosity at the engine's operating temperature. The difference in viscosities for most single-grade oil is too large between the extremes of temperature. To bring the difference in viscosities closer together, special [[polymer]] additives called [[viscosity index improver]]s, or VIIs are added to the oil. These additives are used to make the oil a ''multi-grade'' motor oil, though it is possible to have a multi-grade oil without the use of VIIs. The idea is to cause the multi-grade oil to have the viscosity of the base grade when cold and the viscosity of the second grade when hot. This enables one type of oil to be generally used all year. In fact, when multi-grades were initially developed, they were frequently described as ''all-season oil''. The viscosity of a multi-grade oil still varies logarithmically with temperature, but the slope representing the change is lessened. This slope representing the change with temperature depends on the nature and amount of the additives to the base oil.

The SAE designation for multi-grade oils includes two viscosity grades; for example, ''10W-30'' designates a common multi-grade oil. The two numbers used are individually defined by SAE J300 for [[Motor oil#Single-grade|single-grade]] oils. Therefore, an oil labeled as 10W-30 must pass the SAE J300 viscosity grade requirement for both 10W and 30, and all limitations placed on the viscosity grades (for example, a 10W-30 oil must fail the J300 requirements at 5W). Also, if an oil does not contain any VIIs, and can pass as a multi-grade, that oil can be labelled with either of the two SAE viscosity grades. For example, a very simple multi-grade oil that can be easily made with modern base oils without any VII is a 20W-20. This oil can be labeled as 20W-20, 20W, or 20. Note, if any VIIs are used however, then that oil cannot be labeled as a single grade.

The real-world ability of an oil to crank or pump when cold is potentially diminished soon after it is put into service. The motor oil grade and viscosity to be used in a given vehicle is specified by the manufacturer of the vehicle (although some modern European cars now have no viscosity requirement), but can vary from country to country when climatic or [[fuel efficiency]] constraints come into play.

==Standards==
=== American Petroleum Institute ===

The [[American Petroleum Institute]] (API) sets minimum for performance standards for lubricants. Motor oil is used for the [[lubrication]], cooling, and cleaning of [[internal combustion engine]]s. Motor oil may be composed of a lubricant base stock only in the case of non-[[detergent]] oil, or a lubricant base stock plus additives to improve the oil's detergency, extreme pressure performance, and ability to [[corrosion inhibitor|inhibit]] [[corrosion]] of engine parts. Lubricant base stocks are categorized into five groups by the API. Group I base stocks are composed of [[fractional distillation|fractionally distilled]] [[petroleum]] which is further refined with solvent extraction processes to improve certain properties such as oxidation resistance and to remove wax. Group II base stocks are composed of [[fractional distillation|fractionally distilled]] [[petroleum]] that has been [[hydrocracking|hydrocracked]] to further refine and purify it. Group III base stocks have similar characteristics to Group II base stocks, except that Group III base stocks have higher viscosity indexes. Group III base stocks are produced by further hydrocracking of Group II base stocks, or of hydroisomerized slack wax, (a byproduct of the dewaxing process). Group IV base stock are [[polyalphaolefin]]s (PAOs). Group V is a catch-all group for any base stock not described by Groups I to IV. Examples of group V base stocks include [[polyol]] [[ester]]s, [[polyalkylene glycol]]s (PAG oils), and [[perfluoropolyalkylether]]s (PFPAEs). Groups I and II are commonly referred to as [[mineral oil]]s, group III is typically referred to as synthetic (except in Germany and Japan, where they must not be called synthetic) and group IV is a synthetic oil. Group V base oils are so diverse that there is no catch-all description.

The API service classes<ref name="API_service_categories">[http://new.api.org/certifications/engineoil/categories/index.cfm API Service Categories]</ref> have two general classifications: ''S'' for "service" (originating from spark ignition) (typical passenger cars and light trucks using [[gasoline engine]]s), and ''C'' for "commercial" (originating from compression ignition) (typical [[Diesel engine|diesel]] equipment). Engine oil which has been tested and meets the API standards may display the API Service Symbol (also known as the "Donut") with the service designation on containers sold to oil users.<ref name="API_service_categories" />

The API oil classification structure has eliminated specific support for wet-clutch motorcycle applications in their descriptors, and API SJ and newer oils are referred to be specific to automobile and light truck use. Accordingly, [[motorcycle oil]]s are subject to their own unique standards.

The latest API service standard designation is SN for gasoline automobile and light-truck engines. The SN standard refers to a group of laboratory and engine tests, including the latest series for control of high-temperature deposits. Current API service categories include SN,SM, SL and SJ for gasoline engines. All previous service designations are obsolete, although motorcycle oils commonly still use the SF/SG standard.

All the current gasoline categories (including the obsolete SH), have placed limitations on the phosphorus content for certain SAE viscosity grades (the xW-20, xW-30) due to the chemical poisoning that phosphorus has on catalytic converters. Phosphorus is a key anti-wear component in motor oil and is usually found in motor oil in the form of [[Zinc dithiophosphate]]. Each new API category has placed successively lower phosphorus and zinc limits, and thus has created a controversial issue obsolescing oils needed for older engines, especially engines with sliding (flat/cleave) tappets. API, and ILSAC, which represents most of the worlds major automobile/engine manufactures, states API SM/ILSAC GF-4 is fully backwards compatible, and it is noted that one of the engine tests required for API SM, the Sequence IVA, is a sliding tappet design to test specifically for cam wear protection. However, not everyone is in agreement with backwards compatibility, and in addition, there are special situations, such as "performance" engines or fully race built engines, where the engine protection requirements are above and beyond API/ILSAC requirements. Because of this, there are specialty oils out in the market place with higher than API allowed phosphorus levels. Most engines built before 1985 have the flat/cleave bearing style systems of construction, which is sensitive to reducing zinc and phosphorus. Example; in API SG rated oils, this was at the 1200-1300 ppm level for zincs and phosphorus, where the current SM is under 600 ppm. This reduction in anti-wear chemicals in oil has caused pre-mature failures of camshafts and other high pressure bearings in many older automobiles and has been blamed for pre-mature failure of the oil pump drive/cam position sensor gear that is meshed with camshaft gear in some modern engines.

There are six [[diesel engine]] service designations which are current: CJ-4, CI-4, CH-4, CG-4, CF-2, and CF. Some manufacturers continue to use obsolete designations such as CC for small or stationary diesel engines. In addition, API created a separated CI-4 PLUS designation in conjunction with CJ-4 and CI-4 for oils that meet certain extra requirements, and this marking is located in the lower portion of the API Service Symbol "Donut".

It is possible for an oil to conform to both the gasoline and diesel standards. In fact, it is the norm for all diesel rated engine oils to carry the "corresponding" gasoline specification. For example, API CJ-4 will almost always list either SL or SM, API CI-4 with SL, API CH-4 with SJ, and so on.

===ILSAC===
The International Lubricant Standardization and Approval Committee (ILSAC) also has standards for motor oil. Introduced in 2004, GF-4<ref>[http://www.ilma.org/resources/ilsac_finalstd011404.pdf ILSAC GF-4 Standard for Passenger Car Engine Oil] - ILSAC</ref> applies to SAE 0W-20, 5W-20, 0W-30, 5W-30, and 10W-30 viscosity grade oils. A new set of specifications, GF-5, <ref>[http://www.gf-5.com/uploads/File/ILSAC_GF-5_Dec-22-09_final.pdf ILSAC GF-5 Standard for Passenger Car Engine Oil]</ref> took effect in October of 2010. The industry has one year to convert their oils to GF-5 and in September of 2011, ILSAC will no longer offer licensing for GF-4. In general, ILSAC works with API in creating the newest gasoline oil specification, with ILSAC adding an extra requirement of fuel economy testing to their specification. For GF-4, a Sequence VIB Fuel Economy Test (ASTM D6837) is required that is not required in API service category SM.

A key new test for GF-4, which is also required for API SM, is the Sequence IIIG, which involves running a 3.8 L (232 in³), [[GM 3800 engine|GM 3.8 L V-6]] at {{Convert|125|hp|kW|abbr=on}}, 3,600 rpm, and 150 °C (300 °F) oil temperature for 100 hours. These are much more severe conditions than any API-specified oil was designed for: cars which typically push their oil temperature consistently above 100 °C (212 °F) are most [[Turbocharger|turbocharged]] engines, along with most engines of European or Japanese origin, particularly small capacity, high power output.

The IIIG test is about 50% more difficult<ref>[http://www.astmtmc.cmu.edu/docs/gas/sequenceiii/procedure_and_ils/IIIG/Sequence%20IIIG%20Research%20Report%2002-24-04.pdf Development of the Sequence IIIG Engine Oil Test] - ASTM Research Report</ref> than the previous IIIF test, used in GF-3 and API SL oils. Engine oils bearing the API starburst symbol since 2005 are ILSAC GF-4 compliant.<ref>[http://www.ilma.org/resources/ilsac_finalstd011404.pdf GF-4 Compliance]</ref>

To help consumers recognize that an oil meets the ILSAC requirements, API developed a "starburst" certification mark.

===ACEA===
The ACEA (''[[European Automobile Manufacturers Association|Association des Constructeurs Européens d'Automobiles]]'') performance/quality classifications A3/A5 tests used in [[Europe]] are arguably more stringent than the API and ILSAC standards. CEC (The Co-ordinating European Council) is the development body for fuel and lubricant testing in Europe and beyond, setting the standards via their European Industry groups; ACEA, ATIEL, ATC and CONCAWE.

===JASO===
The [[Japanese Automotive Standards Organization]] (JASO) has created their own set of performance and quality standards for petrol engines of Japanese origin.

For 4-stroke gasoline engines, the JASO T904 standard is used, and is particularly relevant to motorcycle engines. The JASO T904-MA and MA2 standards are designed to distinguish oils that are approved for wet clutch use, and the JASO T904-MB standard is not suitable for wet clutch use.

For 2-stroke gasoline engines, the JASO M345 (FA, FB, FC) standard is used, and this refers particularly to low ash, lubricity, detergency, low smoke and exhaust blocking.

These standards, especially JASO-MA and JASO-FC, are designed to address oil-requirement issues not addressed by the API service categories.

===OEM standards divergence===
By the early 1990s, many of the [[European Union|European]] [[original equipment manufacturer]] (OEM) car manufacturers felt that the direction of the American API oil standards was not compatible with the needs of a motor oil to be used in their motors. As a result many leading European motor manufacturers created and developed their own "OEM" oil standards.

Probably the most well known of these are the VW50*.0* series from [[Volkswagen Group]], and the MB22*.** from [[Mercedes-Benz]]. Other European OEM standards are from [[General Motors]], for the [[Vauxhall Motors|Vauxhall]], [[Opel]] and [[Saab Automobile|Saab]] brands, the [[Ford Motor Company|Ford]] "WSS" standards, [[BMW]] Special Oils and BMW Longlife standards, [[Porsche]], and the [[PSA Peugeot Citroën|PSA]] Group of [[Peugeot]] and [[Citroën]]. General Motors also has the 4718M standard that is used for the [[Chevrolet Corvette]], a standard that is used in North America for selected North American performance engines, with a "Use [[Mobil 1]] only" sticker usually placed on those cars.{{Citation needed|date=April 2009}}

In recent times, very highly specialized "extended drain" "longlife" oils have arisen, whereby, taking Volkswagen Group vehicles, a petrol engine can now go up to 2 years or 30,000 km (~18,600 mi), and a diesel engine can go up to 2 years or 50,000 km (~31,000 mi) - before requiring an oil change. Volkswagen (504.00), BMW, GM, Mercedes and PSA all have their own similar longlife oil standards.{{Citation needed|date=November 2008}}
Another trend of today represent midSAP (sulfated ash <0,8 wt.-%) and lowSAP (sulfated ash <0,5 wt.-%) engine oil (see specifications: Renault RN 0720, FORD WSS-M2C934-A). The ACEA specifications C1 to C4 reflect the midSAP and lowSAP needs of automotive OEMs.
Furthermore, virtually all European OEM standards require a long drains of 30.000 km and up by using HTHS (High Temperature, High Shear) viscosity, many around the 3.5 cP (3.5 mPa·s). In Japan, the HTHS figures are low as >2.6 mPas.

Because of the real or perceived need for motor oils with unique qualities, many modern European cars will demand a specific OEM-only oil standard. As a result, they may make no reference at all to API standards, nor SAE viscosity grades. They may also make no primary reference to the ACEA standards, with the exception of being able to use a "lesser" ACEA grade oil for "emergency top-up", though this usually has strict limits, often up to a maximum of ½ a litre of non-OEM oil.

==Other additives==
In addition to the viscosity index improvers, motor oil manufacturers often include other additives such as [[detergent]]s and dispersants to help keep the engine clean by minimizing sludge buildup, [[corrosion inhibitor]]s, and alkaline additives to neutralize acidic oxidation products of the oil. Most commercial oils have a minimal amount of [[zinc dialkyldithiophosphate]] as an anti-wear additive to protect contacting metal surfaces with [[zinc]] and other compounds in case of metal to metal contact. The quantity of zinc dialkyldithiophosphate is limited to minimize adverse effect on [[catalytic converter]]s. Another aspect for after-treatment devices is the deposition of oil ash, which increases the exhaust back pressure and reduces over time the fuel economy. The so-called "chemical box" limits today the concentrations of sulfur, ash and phosphorus (SAP).

There are other additives available commercially which can be added to the oil by the user for purported additional benefit. Some of these additives include:

* [[Zinc dialkyldithiophosphate]] (ZDDP) additives, which typically also contain calcium sulfonates, are available to consumers for additional protection under extreme-pressure conditions or in heavy duty performance situations. ZDDP and calcium additives are also added to protect motor oil from oxidative breakdown and to prevent the formation of sludge and varnish deposits.
* In the 1980s and 1990s, additives with suspended [[PTFE]] particles were available e.g. "Slick50" to consumers to increase motor oil's ability to coat and protect metal surfaces. There is controversy as to the actual effectiveness of these products as they can coagulate and clog the oil filters.
* Some [[molybdenum disulfide]] containing additives to lubricating oils are claimed to reduce friction, bond to metal, or have anti-wear properties. They were used in WWII in flight engines and became commercial after WWII until the 1990s. They were commercialized in the 1970s (ELF ANTAR Molygraphite) and are today still available (Liqui Moly MoS2 10 W-40, www.liqui-moly.de).
* Various other [[EP additive|extreme-pressure additives]] and [[AW additive|antiwear additives]].
* Many patents proposed use perfluoropolymers to reduce friction between metal parts, such as PTFE (Teflon), or micronized PTFE. However, the application obstacle of PTFE is insolubility in lubricant oils. Their application is questionable.
Very recently, motor oil soluble phosphorus-containing functional poly[tetrafluoroethylene-co-vinylcarbonate-co-vinylphosphoric ester] has put on to test market. The fluorinated functional copolymers has metal bonding groups, oleophilic groups and tetrafluoroethylene (TFE) in main chain. This lubricant additive under trademark Fuelsav™ is desined for improving fuel economy.
The performance of Fuelsav™ is related to functional fluoropolymer structures. The oleophilic groups make Fuelsav™ with solubility in engine oils and transmission fluids. Fuelsav™ has metal bonding groups. The metal bonding groups provide Fuelsav™ with the capability to form fluoropolymer surface films by tribochemical reactions. The solubility in lubricant oil provides self-renewability of the fluoropolymer surface films.
The fluoropolymer surface films formed by lubricant additive Fuelsav™ has the advantage of retain lubricant oil into fluoropolymer surface films with oleophilic groups. Fuel saving is related to the performance of fluoropolymer surface films that smooth, slick and reduce surface boundary layer thickness. The surface fluoropolymer films dramatically reduces friction and wear.

==Synthetic oil and synthetic blends==
[[Synthetic lubricants]] were first synthesized, or man-made, in significant quantities as replacements for mineral lubricants (and fuels) by German scientists in the late 1930s and early 1940s because of their lack of sufficient quantities of crude for their (primarily military) needs. A significant factor in its gain in popularity was the ability of synthetic-based lubricants to remain fluid in the sub-zero temperatures of the Eastern front in wintertime, temperatures which caused petroleum-based lubricants to solidify owing to their higher wax content. The use of synthetic lubricants widened through the 1950s and 1960s owing to a property at the other end of the temperature spectrum, the ability to lubricate aviation engines at temperatures that caused mineral-based lubricants to break down. In the mid 1970s, synthetic motor oils were formulated and commercially applied for the first time in automotive applications. The same SAE system for designating motor oil [[viscosity]] also applies to [[synthetic oils]].

Instead of making motor oil with the conventional petroleum base, "true" [[synthetic oil]] base stocks are artificially synthesized. Synthetic oils are derived from either Group III mineral base oils, Group IV, or Group V non-mineral bases. True synthetics include classes of lubricants like synthetic [[esters]] as well as "others" like GTL (Methane Gas-to-Liquid) (Group V) and [[polyalpha-olefins]] (Group IV). Higher purity and therefore better property control theoretically means synthetic oil has good mechanical properties at extremes of high and low temperatures. The molecules are made large and "soft" enough to retain good viscosity at higher temperatures, yet branched molecular structures interfere with solidification and therefore allow flow at lower temperatures. Thus, although the viscosity still decreases as temperature increases, these synthetic motor oils have a much improved viscosity index over the traditional petroleum base. Their specially designed properties allow a wider temperature range at higher and lower temperatures and often include a lower pour point. With their improved viscosity index, true synthetic oils need little or no viscosity index improvers, which are the oil components most vulnerable to thermal and mechanical degradation as the oil ages, and thus they do not degrade as quickly as traditional motor oils. However, they still fill up with particulate matter, although at a lower rate compared to conventional oils, and the oil filter still fills and clogs up over time. So, periodic oil and filter changes should still be done with synthetic oil; but some synthetic oil suppliers suggest that the intervals between oil changes can be longer, sometimes as long as 16,000-24,000 km (10,000–15,000 mi) primarily due to reduced degredation by oxidation.

Tests {{Citation needed|date=August 2008}} do show that fully synthetic oil is superior in extreme service conditions to conventional oil. But in the vast majority of vehicle applications, mineral oil based lubricants, sometimes fortified with synthetic additives and with the benefit of over a century of development, continues to be the predominant and satisfactory lubricant for most internal combustion engine applications.

==Bio-based oils==
Bio-based oils existed prior to the development of petroleum-based oils in the 19th Century. They have become the subject of renewed interest with the advent of bio-fuels and the push for green products. The development of canola-based motor oils began in 1996 in order to pursue environmentally friendly products. Purdue University has funded a project to develop and test such oils. Test results indicate satisfactory performance from the oils tested.<ref>[http://www.hort.purdue.edu/newcrop/ncnu02/v5-029.html Canola-based Motor Oils] - Perdue University</ref>

==Maintenance==
[[File:Oil Change oil pan 2005 gmc suv.JPG|thumb|Oil being drained from a car]]

In engines, there is inevitably some exposure of the oil to products of internal combustion, and microscopic [[Coke (fuel)|coke]] particles from black [[soot]] accumulate in the oil during operation. Also the rubbing of metal engine parts inevitably produces some microscopic metallic particles from the wearing of the surfaces. Such particles could circulate in the oil and grind against the part surfaces causing [[wear]]. The [[oil filter]] removes many of the particles and sludge, but eventually the oil filter can become clogged, if used for extremely long periods. The motor oil and especially the additives also undergo thermal and mechanical degradation. For these reasons, the oil and the oil filter need to be periodically replaced. While there is a full industry surrounding regular oil changes and maintenance, an oil change is fairly simple and something car owners can do themselves.

Some vehicle manufacturers may specify which SAE viscosity grade of oil should be used, but different viscosity motor oil may perform better based on the operating environment. Many manufacturers have varying requirements and have designations for motor oil they require to be used. Some quick oil change shops recommended intervals of 5,000 km (3,000 mi) or every 3 months which is not necessary according to many automobile manufacturers. This has led to a campaign by the California EPA against the [[3,000 mile myth]], promoting vehicle manufacturer's recommendations for oil change intervals over those of the oil change industry.

Motor oil is changed on time in service or distance vehicle has traveled. Actual operating conditions and engine hours of operation are a more precise indicator of when to change motor oil. Also important is the quality of the oil used especially when synthetics are used (synthetics are more stable than conventional oils). Some manufactures address this (IE. BMW and VW with their respective long-live standards) while others do not. The viscosity can be adjusted for the ambient temperature change, thicker for summer heat and thinner for the winter cold. Lower viscosity oils are used in many newer American market vehicles. Time-based intervals account for the short trip driver who drives fewer miles, but builds up more contaminants. It is advised by manufacturers to not exceed their time or distance driven on a motor oil change interval. Many modern cars now list somewhat higher intervals for changing of oil and filter, with the constraint of "severe" service requiring more frequent changes with less-than ideal driving; this applies to short trips of under 16 km (10 mi), where the oil does not get to full operating temperature long enough to burn off condensation, excess fuel, and other contamination that leads to "sludge", "varnish", "acids", or other deposits. Many manufacturers have engine computer calculations to estimate the oil's condition based on the factors which degrade it such as RPMs, temperatures, and trip length; and one system adds an optical sensor for determining the clarity of the oil in the engine. These systems are commonly known as Oil Life Monitors or OLMs. In the 1970s typical cars took heavy 10W-40 oil. In the 1980s 5W-30 oils were introduced to improve fuel efficiency. A modern typical application would be Honda Motor's use of 5W-20 viscosity oil for 12,000 km (7,500 mi) while offering increased fuel efficiency. Due to many new engine designs having tolerances of a few one-thousandths of an inch, advanced oil-actuated cam and valve timing systems, many manufacturers are recommending an oil weight of 5W-20 to be used in their engines.

==Future==
A new process to break down [[polyethylene]], a common [[plastic]] product found in many consumer containers, is used to make wax with the correct molecular properties for conversion into a lubricant, bypassing the expensive [[Fischer-Tropsch process]]. The plastic is melted and then pumped into a [[furnace]]. The heat of the furnace breaks down the molecular chains of polyethylene into wax. Finally, the wax is subjected to a [[catalytic]] process that alters the wax's molecular structure, leaving a clear oil. (Miller, ''et al.'', 2005)

Biodegradable Motor Oils based on esters or hydrocarbon-ester blends appeared in the 1990s followed by formulations beginning in 2000 which respond to the bio-no-tox-criteria of the European preparations directive (EC/1999/45).<ref>Directive 1999/45/EC of the European Parliament and of the Council concerning the approximation of the laws, regulations and administrative provisions of the member states relating to the classification, packaging and labelling of dangerous preparations, Official Journal of the European Communities L200/1, 30.07.1999, ISSN 0376-9461</ref> This means, that they not only are biodegradable according to OECD 301x test methods, but also the aquatic toxicities (fish, algae, daphnie) are each above 100 mg/L.

Another class of base oils suited for engine oils represents the polyalkylene glycols. They offer zero-ash, bio-no-tox properties and lean burn characteristics.<ref>M. Woydt, No /Low SAP and Alternative Engine Oil Development and Testing, Journal of ASTM International, 2007, Vol. 4, No.10, online ISSN 1546-962X or in ASTM STP 1501 “ Automotive Lubricants – Testing and Additive Development”, 03.-05. December 2006, Orlando, ISBN 978-0-8031-4505-4, eds.: Tung/Kinker/Woydt</ref>

==Re-refined motor oil==
The oil in a motor oil product does not break down or burn as it is used in an engine—it simply gets contaminated with particles and chemicals that make it a less effective lubricant. Re-refining cleans the contaminants and used additives out of the dirty oil. From there, this clean “base stock” is blended with some virgin base stock and a new additives package to make a finished lubricant product that can be just as effective as lubricants made with all virgin oil.<ref>http://fleetsuserro.org/what.htm</ref> The US Environmental Protection Agency defines re-refined products as containing at least 25% re-refined base stock,<ref>U.S. EPA Comprehensive Procurement Guidelines: Re-refined Lubricating Oil http://www.epa.gov/osw/conserve/tools/cpg/products/lubricat.htm</ref> but other standards are significantly higher. The California State public contract code define a re-refined motor oil as one that contains at least 70% re-refined base stock.<ref>California State Contract Code 12209 http://law.onecle.com/california/public-contract/12209.html</ref>

==Brands and manufacturers==
{{Example farm|date=September 2010}}

{{columns-list|3|
* [[Acdelco Lubricants]]
* [[Agip]]
* [[Advanced Lubrication Specialties, Inc]]
* [[Amsoil]]
* [[Amalie]]
* [[Bardahl]]
* [[Bharat Petroleum]]
* [[Cepsa]]
* [[Chevron Corporation|Chevron]]
* [[Castrol]] ([[BP]])
* [[Citgo]]
* Cross Oil Refining
* David Weber Oil Co.
* Delo ([[Chevron Corporation|Chevron]])
* [[Elf Aquitaine|Elf]]
* Elofic Lubricants
* [[Esso]] (outside U.S.)
* [[Exxon]] (U.S. only)
* [[Fuchs Petrolub|Fuchs]]
* [[Green Earth Technologies]]
* [[Great wall]] ([[PetroChina]])
* [[Gulf Oil]]
* [[Havoline]] ([[Texaco]])
* [[Hindustan Petroleum]]
* [[Indian Oil Corporation]]
* Kendall ([[ConocoPhilips]])
* Kunlun([[Sinopec]])
* [[Liqui Moly]]
* Liquoil
* Lubrication Engineers
* Lubriplate Lubricants
* [[Lucas Oil]]
* [[Mobil 1]] ([[Mobil]])
* [[Motul (company)|Motul]]
* [[Motorcraft]]
* [[NEO]]
* [[Oando]]
* [[Pakelo]]
* [[Pakistan State Oil]]
* [[Pennzoil]] / Quaker State
* [[Pentosin]]
* [[Pertamina]]
* [[Petro-Canada]]
* [[Petrobras]]
* [[Petronas]]
* Pinnacle Oil Co.
* [[Prestone]]
* Prolab Technologies
* Q8 (KPI)
* [[Red Line Oil]]
* [[Repsol]]
* Revtex ([[Caltex]])
* [[Royal Dutch Shell]] ([[Shell Oil Company]])
* [[Royal Purple (lubricant manufacturer)|Royal Purple]]
* [[Statoil]] Lubricants
* [[Sunoco]] (Advanced Lubrication Specialties, Inc)
* Speedmaster
* [[Total S.A.]]
* [[Valvoline]] ([[Ashland Inc.]])
* Warren Oil/Coastal/Unilube
* Voltrion oil (electrically treated oils Belgium)
* Warren Performance Products
* [[Wolf's Head (motor oil)|Wolf's Head]]
}}

==Packaging==
{{Expand section|date=September 2010}}
Motor oil came in [[oil can]]s and [[glass bottle]]s before the modern [[plastic bottle]].

==References==
{{Reflist}}

==External links==
{{commonscat}}

* {{Wikihow|Change-the-Oil-in-Your-Car|change the oil in your car}}
* [http://www.acea.be/images/uploads/pub/070308_ACEA_sequences_2007_LD_and_HD.pdf ACEA European Oil Sequences]
* [http://www.roymech.co.uk/Useful_Tables/Tribology/Viscosity.html Table of SAE and ISO viscosity gradings]
* [http://MotorOilBible.com/data-comparisons-combined.pdf A PDF table of motor oil technical specifications]

{{Motor fuel}}

{{DEFAULTSORT:Motor Oil}}
[[Category:Automotive chemicals]]
[[Category:Motor oils]]

[[ar:زيت المحرك]]
[[bg:Стабилност на маслото]]
[[cs:Motorový olej]]
[[de:Schmieröl]]
[[et:Mootoriõli]]
[[es:Aceite de motor]]
[[fa:روغن موتور]]
[[fr:Huile moteur]]
[[id:Oli mesin]]
[[it:Olio lubrificante]]
[[he:שמן מנוע]]
[[ka:ძრავას ზეთი]]
[[hu:Motorolaj]]
[[nl:Smeerolie]]
[[ja:エンジンオイル]]
[[pl:Olej silnikowy]]
[[pt:Óleo lubrificante]]
[[ru:Моторные масла]]
[[sk:Motorový olej]]
[[fi:Moottoriöljy]]
[[sv:Motorolja]]
[[th:น้ำมันหล่อลื่นเครื่องยนต์]]
[[tr:Motor yağı]]
[[zh-yue:偈油]]

Polyurethane

2010-01-01T03:05:26Z

Fluonova: /* Polyols */

{{verylong|date=November 2009}}
A '''polyurethane''', IUPAC abbreviation '''PUR''', but commonly abbreviated '''PU''', is any [[polymer]] consisting of a chain of [[organic chemistry|organic]] units joined by [[carbamate|urethane]] (carbamate) links. Polyurethane polymers are formed through [[step-growth polymerization]] by reacting a [[monomer]] containing at least two [[isocyanate]] [[functional group]]s with another monomer containing at least two [[hydroxyl]] ([[alcohol]]) groups in the presence of a [[catalyst]].

Polyurethane formulations cover an extremely wide range of stiffness, hardness, and densities. These materials include:
* Low-density flexible [[foam]] used in [[upholstery]], bedding, and automotive and truck seating
* Low-density rigid foam used for [[thermal insulation]] and [[Transfer molding|RTM]] cores
* Soft solid [[elastomers]] used for gel pads and print rollers
* Low density [[elastomers]] used in footwear
* Hard solid plastics used as electronic instrument bezels and structural parts

Polyurethanes are widely used in high resiliency flexible foam seating, rigid foam insulation panels, microcellular foam [[seal (mechanical)|seal]]s and [[gasket]]s, durable elastomeric wheels and tires, automotive suspension [[Bushing (isolator)|bushings]], electrical potting compounds, high performance [[adhesive]]s and sealants, [[Spandex]] [[Synthetic fiber|fibers]], seals, gaskets, [[carpet]] underlay, and hard plastic parts.

Polyurethane products are often called "urethanes". They should not be confused with the specific substance urethane, also known as [[ethyl carbamate]]. Polyurethanes are neither produced from ethyl carbamate, nor do they contain it.

==History==
The pioneering work on polyurethane polymers was conducted by [[Otto Bayer]] and his coworkers in [[1937]] at the laboratories of [[I.G. Farben]] in Leverkusen, Germany.<ref>see German Patent 728.981 (1937) I.G. Farben</ref> They recognized that using the polyaddition principle to produce polyurethanes from liquid diisocyanates and liquid [[polyether]] or [[polyester]] diols seemed to point to special opportunities, especially when compared to already existing plastics that were made by polymerizing olefins, or by [[polycondensation]]. The new monomer combination also circumvented existing patents obtained by [[Wallace Carothers]] on [[polyester]]s.<ref name=Seymour>''Polyurethanes: A Class of Modern Versatile Materials'' Raymond B. Seymour [[George B. Kauffman]] [[J. Chem. Ed.]] 69, 909 '''1992'''</ref> Initially, work focused on the production of fibres and flexible foams. With development constrained by [[World War II]] (when PUs were applied on a limited scale as aircraft coating<ref name=Seymour/>), it was not until 1952 that polyisocyanates became commercially available. Commercial production of flexible polyurethane foam began in 1954, based on [[toluene diisocyanate]] (TDI) and polyester polyols. The invention of these foams (initially called ''imitation [[swiss cheese]]'' by the inventors<ref name=Seymour/>) was thanks to water accidentally introduced in the [[chemical reaction|reaction]] mix. These materials were also used to produce rigid foams, gum rubber, and [[elastomer]]s. Linear fibres were produced from [[hexamethylene diisocyanate]] (HDI) and [[1,4-butanediol]] (BDO).

The first commercially available polyether polyol, [[poly(tetramethylene ether) glycol]], was introduced by [[DuPont]] in 1956 by polymerizing [[tetrahydrofuran]]. Less expensive polyalkylene glycols were introduced by [[BASF]] and [[Dow Chemical]] the following year, 1957. These polyether polyols offered technical and commercial advantages such as low cost, ease of handling, and better hydrolytic stability; and quickly supplanted polyester polyols in the manufacture of polyurethane goods. Other PU pioneers were [[Union Carbide]] and the [[Mobay|Mobay corporation]], a U.S. Monsanto/Bayer joint venture.<ref name=Seymour/> In 1960 more than 45,000 tons of flexible polyurethane foams were produced. As the decade progressed, the availability of [[chlorofluoroalkane]] blowing agents, inexpensive polyether polyols, and [[methylene diphenyl diisocyanate]] (MDI) heralded the development and use of polyurethane rigid foams as high performance insulation materials. Rigid foams based on polymeric MDI (PMDI) offered better thermal stability and combustion characteristics than those based on TDI. In 1967, urethane modified [[polyisocyanurate]] rigid foams were introduced, offering even better thermal stability and [[flammability]] resistance to low-density insulation products. Also during the 1960s, automotive interior safety components such as instrument and door panels were produced by back-filling [[thermoplastic]] skins with semi-rigid foam.

In 1969, Bayer AG exhibited an all plastic car in Dusseldorf, Germany. Parts of this car were manufactured using a new process called RIM, [[Reaction Injection Molding]]. RIM technology uses high-pressure impingement of liquid components followed by the rapid flow of the reaction mixture into a mold cavity. Large parts, such as automotive [[fascia]] and body panels, can be molded in this manner. Polyurethane RIM evolved into a number of different products and processes. Using [[diamine]] [[chain extender]]s and [[trimerization]] technology gave poly(urethane urea), poly(urethane isocyanurate), and polyurea RIM. The addition of fillers, such as milled glass, [[mica]], and processed mineral fibres gave arise to RRIM, reinforced RIM, which provided improvements in [[flexural modulus]] (stiffness) and thermal stability. This technology allowed production of the first plastic-body automobile in the United States, the [[Pontiac Fiero]], in 1983. Further improvements in flexural modulus were obtained by incorporating preplaced glass mats into the RIM mold cavity, also known as SRIM, or structural RIM.

Starting in the early 1980s, water-blown microcellular flexible foam was used to mold gaskets for panel and radial seal air filters in the automotive industry. Since then, increasing energy prices and the desire to eliminate [[PVC]] plastisol from automotive applications have greatly increased market share. Costlier raw materials are offset by a significant decrease in part weight and in some cases, the elimination of metal end caps and filter housings. Highly filled polyurethane elastomers, and more recently unfilled polyurethane foams are now used in high-temperature oil filter applications.

Polyurethane foam (including foam rubber) is often made by adding small amounts of volatile materials, so-called [[blowing agent]]s, to the reaction mixture. These simple volatile chemicals yield important performance characteristics, primarily thermal insulation. In the early 1990s, because of their impact on [[ozone depletion]], the [[Montreal Protocol]] led to the greatly reduced use of many [[chlorine]]-containing blowing agents, such as [[trichlorofluoromethane]] (CFC-11). Other [[haloalkanes]], such as the hydrochlorofluorocarbon [[1,1-dichloro-1-fluoroethane]] (HCFC-141b), were used as interim replacements until their phase out under the [[IPPC]] directive on [[greenhouse gas]]es in 1994 and by the Volatile Organic Compounds (VOC) directive of the [[European Union|EU]] in 1997 (See: [[Haloalkane]]s). By the late 1990s, the use of blowing agents such as [[carbon dioxide]], [[pentane]], [[1,1,1,2-tetrafluoroethane]] (HFC-134a) and [[1,1,1,3,3-pentafluoropropane]] (HFC-245fa) became more widespread in North America and the EU, although chlorinated blowing agents remained in use in many developing countries.<ref>{{cite conference
| first =Bert
| last =Feske
| authorlink =
| coauthors =
| title =The Use of Saytex RB-9130/9170 Low Viscosity Brominated
Flame Retardant Polyols in HFC-245fa and High Water
Formulations
| booktitle =
| pages =
| publisher =Alliance for the Polyurethane Industry Technical Conference
| date =October 2004
| location =Las Vegas, NV
| url =
| doi =
| id =
| accessdate =2007-08-01}}</ref>

Building on existing polyurethane spray coating technology and polyetheramine chemistry, extensive development of two-component polyurea spray elastomers took place in the 1990s. Their fast reactivity and relative insensitivity to [[moisture]] make them useful coatings for large surface area projects, such as secondary containment, manhole and tunnel coatings, and tank liners. Excellent [[adhesion]] to [[concrete]] and [[steel]] is obtained with the proper primer and surface treatment. During the same period, new two-component polyurethane and hybrid polyurethane-polyurea elastomer technology was used to enter the marketplace of spray-in-place load bed liners. This technique for coating pickup truck beds and other cargo bays creates a durable, abrasion resistant composite with the metal substrate, and eliminates corrosion and brittleness associated with drop-in thermoplastic bed liners.

The potential for polyols derived from [[vegetable oil]]s to replace petrochemical-based polyols began garnering attention beginning around 2004, partly due to the rising costs of [[petrochemical]] [[feedstock]]s and partially due to an enhanced public desire for [[environmentally friendly]] [[green chemistry|green]] products.<ref name="ussc">{{cite conference
| last =Niemeyer
| first =Timothy
| coauthors =Patel, Munjal and Geiger, Eric
| title =A Further Examination of Soy-Based Polyols in Polyurethane Systems
| booktitle =
| publisher = Alliance for the Polyurethane Industry Technical Conference
| date = September, 2006
| location = Salt Lake City, UT
| accessdate = 2007-08-01 }}</ref> One of the most vocal supporters of these polyurethanes made using [[natural oil polyols]] is the [[Ford Motor Company]].<ref>{{cite news | last = | first = | title =New Twist on Green: 2008 Ford Mustang Seats Will Be Soy-Based Foam
| publisher =Edmunds inside line| date =July 12, 2007 | url =http://www.edmunds.com/insideline/do/News/articleId=121682| accessdate =2007-10-02}}</ref>

==Chemistry==

{| class="toccolours" border="1" style="clear: both; margin: 0.5em; margin-left: 1em; float: right; border-collapse: collapse;"
| align="center" style="letter-spacing: 1px; color: black; background-color: #efefef;" | '''{{{name|generalized polyurethane reaction}}}'''
|-
| align="center" colspan="1" bgcolor="white" style="padding: 0.5em;" | [[Image:Generalizedpolyurethanereaction.png|300px|generalized polyurethane reaction]]
|-
|}

Polyurethanes are in the class of compounds called '''reaction polymers''', which include [[Epoxy|epoxies]], [[Polyester|unsaturated polyesters]], and [[phenolics]].<ref name="Gum 1992">{{cite book | first=Wilson | last=Gum | coauthors=Riese, Wolfram; Ulrich, Henri | title=Reaction Polymers | publisher=Oxford University Press | location=New York | year=1992 | isbn=0-19-520933-8}}</ref><ref>{{cite book | first=Ron | last=Harrington | coauthors=Hock, Kathy | title= Flexible Polyurethane Foams | publisher=The Dow Chemical Company | location=Midland | year=1991 | id=}}</ref><ref name="Oertel 1985">{{cite book | first=Gunter | last=Oertel | coauthors= | title=Polyurethane Handbook | publisher=Macmillen Publishing Co., Inc. | location=New York | year=1985 | isbn=0-02-948920-2}}</ref><ref>{{cite book | first=Henri | last=Ulrich | coauthors= | title=Chemistry and Technology of Isocyanates | publisher=John Wiley & Sons, Inc. | location=New York | year=1996 | isbn=0-471-96371-2}}</ref><ref>{{cite book | first=George | last=Woods | coauthors= | title= The ICI Polyurethanes Book | publisher=John Wiley & Sons, Inc. | location=New York | year=1990 | isbn=0-471-92658-2}}</ref> A [[urethane]] linkage is produced by reacting an [[isocyanate]] group, -N=C=O with a [[hydroxyl]] ([[alcohol]]) group, -OH. Polyurethanes are produced by the polyaddition reaction of a polyisocyanate with a polyalcohol (polyol) in the presence of a catalyst and other additives. In this case, a polyisocyanate is a molecule with two or more isocyanate functional groups, R-(N=C=O)n ≥ 2 and a polyol is a molecule with two or more hydroxyl functional groups, R'-(OH)n ≥ 2. The reaction product is a polymer containing the urethane linkage, -RNHCOOR'-. Isocyanates will react with any molecule that contains an active hydrogen. Importantly, isocyanates react with water to form a [[urea]] linkage and [[carbon dioxide]] gas; they also react with [[polyetheramines]] to form [[polyurea]]s. Commercially, polyurethanes are produced by reacting a liquid isocyanate with a liquid blend of polyols, [[catalyst]], and other additives. These two components are referred to as a polyurethane system, or simply a system. The isocyanate is commonly referred to in North America as the 'A-side' or just the 'iso'. The blend of polyols and other additives is commonly referred to as the 'B-side' or as the 'poly'. This mixture might also be called a 'resin' or 'resin blend'. In Europe the meanings for 'A-side' and 'B-side' are reversed. Resin blend additives may include chain extenders, [[cross linker]]s, [[surfactant]]s, [[flame retardant]]s, [[blowing agent]]s, [[pigment]]s, and [[filler]]s.

The first essential component of a polyurethane polymer is the isocyanate. Molecules that contain two isocyanate groups are called diisocyanates. These molecules are also referred to as [[monomers]] or monomer units, since they themselves are used to produce polymeric isocyanates that contain three or more isocyanate functional groups. Isocyanates can be classed as [[aromatic]], such as [[diphenylmethane diisocyanate]] (MDI) or [[toluene diisocyanate]] (TDI); or [[aliphatic]], such as [[hexamethylene diisocyanate]] (HDI) or [[isophorone diisocyanate]] (IPDI). An example of a polymeric isocyanate is polymeric diphenylmethane diisocyanate, which is a blend of molecules with two-, three-, and four- or more isocyanate groups, with an average functionality of 2.7. Isocyanates can be further modified by partially reacting them with a polyol to form a [[prepolymer]]. A quasi-prepolymer is formed when the [[stoichiometric]] ratio of isocyanate to hydroxyl groups is greater than 2:1. A true prepolymer is formed when the stoichiometric ratio is equal to 2:1. Important characteristics of isocyanates are their molecular backbone, % NCO content, functionality, and [[viscosity]].

The second essential component of a polyurethane polymer is the polyol. Molecules that contain two hydroxyl groups are called [[diol]]s, those with three hydroxyl groups are called triols, et cetera. In practice, polyols are distinguished from short chain or low-molecular weight glycol chain extenders and cross linkers such as [[ethylene glycol]] (EG), [[1,4-butanediol]] (BDO), [[diethylene glycol]] (DEG), [[glycerine]], and [[trimethylol propane]] (TMP). Polyols are polymers in their own right. They are formed by [[Acid catalysis|base-catalyzed]] addition of [[propylene oxide]] (PO), [[ethylene oxide]] (EO) onto a hydroxyl or amine containing initiator, or by polyesterification of a di-acid, such as [[adipic acid]], with glycols, such as ethylene glycol or [[dipropylene glycol]] (DPG). Polyols extended with PO or EO are [[polyether]] polyols. Polyols formed by polyesterification are [[polyester]] polyols. The choice of initiator, extender, and molecular weight of the polyol greatly affect its physical state, and the physical properties of the polyurethane polymer. Important characteristics of polyols are their molecular backbone, initiator, molecular weight, % primary hydroxyl groups, functionality, and viscosity.

{| class="toccolours" border="1" style=" clear: both; margin: 0.5em; margin-left: 1em; float: right; border-collapse: collapse;"
| align="center" style="letter-spacing: 1px; color: black; background-color: #efefef;" | '''{{{name|PU reaction mechanism catalyzed by a tertiary amine}}}'''
|-
| align="center" colspan="1" bgcolor="white" style="padding: 0.5em;" | [[Image:PUaminemechanism.png|480px|reaction meachanism]]
|-
|}


{| class="toccolours" border="1" style="clear: both; margin: 0.5em; margin-left: 1em; float: right; border-collapse: collapse;"
| align="center" style="letter-spacing: 1px; color: black; background-color: #efefef;" | '''{{{name|carbon dioxide gas formed by reacting water and isocyanate}}}'''
|-
| align="center" colspan="1" bgcolor="white" style="padding: 0.5em;" | [[Image:Waterisoreaction.png|480px|water isocyanate reaction]]
|-
|}
The [[polymerization]] reaction is catalyzed by tertiary [[amine]]s, such as [[dimethylcyclohexylamine]], and [[organometallic]] compounds, such as [[dibutyltin dilaurate]] or [[bismuth octanoate]]. Furthermore, catalysts can be chosen based on whether they favor the urethane (gel) reaction, such as 1,4-diazabicyclo[2.2.2]octane (also called [[DABCO]] or TEDA), or the urea (blow) reaction, such as [[bis-(2-dimethylaminoethyl)ether]], or specifically drive the isocyanate [[trimer]]ization reaction, such as [[potassium octoate]].

One of the most desirable attributes of polyurethanes is their ability to be turned into foam. Blowing agents such as water, certain halocarbons such as HFC-245fa ([[1,1,1,3,3-pentafluoropropane]]) and HFC-134a ([[1,1,1,2-tetrafluoroethane]]), and hydrocarbons such as [[n-pentane]], can be incorporated into the poly side or added as an auxiliary stream. Water reacts with the isocyanate to create [[carbon dioxide]] gas, which fills and expands cells created during the mixing process. The reaction is a three step process. A water molecule reacts with an isocyanate group to form a [[carbamic acid]]. Carbamic acids are unstable, and decompose forming carbon dioxide and an amine. The amine reacts with more isocyanate to give a substituted urea. Water has a very low [[molecular weight]], so even though the weight percent of water may be small, the molar proportion of water may be high and considerable amounts of urea produced. The urea is not very soluble in the reaction mixture and tends to form separate "hard segment" phases consisting mostly of polyurea. The concentration and organization of these polyurea phases can have a significant impact on the properties of the polyurethane foam.<ref>{{cite paper
| author =Kaushiva, Byran D.
| title =Structure-Property Relationships of Flexible Polyurethane Foams
| version =PhD Thesis
| publisher =Virginia Polytechnic Institute
| date =August 15, 1999
| url =
| format =
| accessdate = }}</ref>
Halocarbons and hydrocarbons are chosen such that they have [[boiling point]]s at or near [[room temperature]]. Since the polymerization reaction is [[exothermic]], these blowing agents volatilize into a gas during the reaction process. They fill and expand the cellular polymer matrix, creating a foam. It is important to know that the blowing gas does not create the cells of a foam. Rather, foam cells are a result of blowing gas diffusing into bubbles that are nucleated or stirred into the system at the time of mixing. In fact, high-density [[microcellular]] foams can be formed without the addition of blowing agents by mechanically frothing or nucleating the polyol component prior to use.

Surfactants are used to modify the characteristics of the polymer during the foaming process. They are used to [[emulsion|emulsify]] the liquid components, regulate cell size, and stabilize the cell structure to prevent collapse and surface defects. Rigid foam surfactants are designed to produce very fine cells and a very high closed cell content. Flexible foam surfactants are designed to stabilize the reaction mass while at the same time maximizing open cell content to prevent the foam from shrinking. The need for surfactant can be affected by choice of isocyanate, polyol, component compatibility, system reactivity, process conditions and equipment, tooling, part shape, and shot weight.

==Raw materials==
For the manufacture of polyurethane polymers, two groups of at least bifunctional substances are needed as reactants; compounds with isocyanate groups, and compounds with active hydrogen atoms. The physical and chemical character, structure, and molecular size of these compounds influence the polymerization reaction, as well as ease of processing and final physical properties of the finished polyurethane. In addition, additive such as catalysts, surfactants, blowing agents, cross linkers, flame retardants, light stabilizers, and fillers are used to control and modify the reaction process and performance characteristics of the polymer.

===Isocyanates===
[[Isocyanates]] with two or more functional groups are required for the formation of polyurethane polymers. Volume wise, aromatic isocyanates account for the vast majority of global diisocyanate production. Aliphatic and cycloaliphatic isocyanates are also important building blocks for polyurethane materials, but in much smaller volumes. There are a number of reasons for this. First, the aromatically linked isocyanate group is much more reactive than the aliphatic one. Second, aromatic isocyanates are more economical to use. Aliphatic isocyanates are used only if special properties are required for the final product. For example, light stable coatings and elastomers can only be obtained with aliphatic isocyanates. Even within the same class of isocyanates, there is a significant difference in reactivity of the functional groups based on steric hindrance. In the case of 2,4-toluene diisocyanate, the isocyanate group in the para position to the methyl group is much more reactive than the isocyanate group in the ortho position.

[[Phosgene|Phosgenation]] of corresponding amines is the main technical process for the manufacture of isocyanates. The amine raw materials are generally manufactured by the hydrogenation of corresponding nitro compounds. For example, [[toluenediamine]] (TDA) is manufactured from [[dinitrotoluene]], which then converted to toluene diisocyanate (TDI). Diamino diphenylmethane or [[methylenedianiline]] (MDA) is manufactured from [[nitrobenzene]] via [[aniline]], which is then converted to diphenylmethane diisocyanate (MDI).

The two most important aromatic isocyanates are toluene diisocyanate (TDI) and diphenylmethane diisocyanate (MDI). TDI consists of a mixture of the 2,4- and 2,6-diisocyanatotoluene isomers. The most important product is TDI-80 (TD-80), consisting of 80% of the 2,4-isomer and 20% of the 2,6-isomer. This blend is used extensively in the manufacture of polyurethane flexible slabstock and molded foam.<ref>
{{cite web|url=http://dowglobal.beta.ides.com/DocSelect.aspx?DOC=DOWTDS&E=101414|title= Technical data sheet from Dow Chemical|accessdate=2007-09-15}}</ref> TDI, and especially crude TDI and TDI/MDI blends can be used in rigid foam applications, but have been supplanted by polymeric MDI. TDI-polyether and TDI-polyester prepolymers are used in high performance coating and elastomer applications. Prepolymers are available that have been vacuum stripped of TDI monomer, which greatly reduces their toxicity. Diphenylmethane diisocyanate (MDI) has three isomers, 4,4'-MDI, 2,4'-MDI, and 2,2'-MDI, and is also polymerized to provide oligomers of functionality three and higher.
[[Image:MDI isomers.PNG|500px|center|MDI isomers and polymer]]

Only the 4,4'-MDI monomer is sold commercially as a single isomer. It is provided either as a frozen solid or flake, or in molten form, and is used to manufacture high performance prepolymers. Monomer blends, consisting of approximately 50% of the 4,4'-isomer and 50% of the 2,4'-isomer, are liquid at room temperature and are used to manufacture prepolymers for polyurea spray elastomer applications. 4,4'-MDI blends containing MDI uretonimine, carbodiimide, and allophonate moieties are also liquid at room temperature, and are used in the manufacture of integral skin and microcellular foams. 4,4'-MDI-glycol prepolymers offer increased mechanical properties in the same applications, but are prone to freezing at temperatures below 20°C. Polymeric MDI (PMDI) is used in rigid pour-in-place, spray foam, and molded foam applications. Polymeric MDI that contains a very high portion of high-functionality oligomers is used to manufacture polyurethane and polyisocyanurate rigid insulation boardstock. Modified PMDI, which contains high levels of MDI monomer, is used in the production of polyurethane flexible molded and microcellular foam. The relative percentage of the 4,4'- and 2,4'- isomers is adjusted to change the reactivity and storage stability of the isocyanate blend, as well as the firmness and other physical properties of the finished goods. Other aromatic isocyanate include [[p-phenylene diisocyante]] (PPDI), [[naphthalene diisocyanate]] (NDI), and [[o-tolidine diisocyanate]] (TODI).

The most important aliphatic and cycloaliphatic isocyanates are [[hexamethylene diisocyanate|1,6-hexamethylene diisocyanate]] (HDI), 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethyl-cyclohexane ([[isophorone diisocyanate]], IPDI), and [[4,4'-diisocyanato dicyclohexylmethane]] (H12MDI). They are used to produce light stable, non-yellowing polyurethane coatings and elastomers. Because of their toxicity, aliphatic isocyanate monomers are converted into prepolymers, biurets, dimers, and trimers for commercial use. HDI adducts are used extensively for weather and abrasion resistant coatings and lacquers. IPDI is used in the manufacture of coatings, elastomeric adhesives and sealants. H12MDI prepolymers are used to produce high performance coatings and elastomers with optical clarity and hydrolysis resistance. Other aliphatic isocyanates include [[cyclohexane diisocyanate]] (CHDI), [[tetramethylxylene diisocyanate]] (TMXDI), and [[1,3-bis(isocyanatomethyl)cyclohexane]] (H6XDI).

===Polyols===
[[Polyols#Polyols in polymer chemistry|Polyols]] are higher molecular weight materials manufactured from an initiator and monomeric building blocks. They are most easily classified as polyether polyols, which are made by the reaction of [[epoxides]] (oxiranes) with an active hydrogen containing starter compounds, or polyester polyols, which are made by the polycondensation of multifunctional [[carboxylic acid]]s and hydroxyl compounds. They can be further classified according to their end use as flexible or rigid polyols, depending on the functionality of the initiator and their molecular weight. Taking into account functionality, flexible polyols have molecular weights from 2,000 to 10,000 (OH# from 18 to 56). Rigid polyols have molecular weights from 250 to 700 (OH# from 300 to 700). Polyols with molecular weights from 700 to 2,000 (OH# 60 to 280) are used to add stiffness or flexibility to base systems, as well as increase solubility of low molecular weight glycols in high molecular weight polyols.

Polyether polyols come in a wide variety of grades based on their end use, but are all constructed in a similar manner. Polyols for flexible applications use low functionality initiators such as [[dipropylene glycol]] (f=2) or [[glycerine]] (f=3). Polyols for rigid applications use high functionality initiators such [[sucrose]] (f=8), [[sorbitol]] (f=6), [[toluenediamine]] (f=4), and [[Mannich base]]s (f=4). [[Propylene oxide]] is then added to the initiators until the desired molecular weight is achieved. Polyols extended with propylene oxide are terminated with secondary hydroxyl groups. In order to change the compatibility, rheological properties, and reactivity of a polyol, [[ethylene oxide]] is used as a co-reactant to create random or mixed block [[heteropolymer]]s. Polyols capped with ethylene oxide contain a high percentage of primary hydroxyl groups, which are more reactive than secondary hydroxyl groups. Because of their high viscosity (470 OH# sucrose polyol, 33,000 cps at 25°C), carbohydrate initiated polyols often use glycerine or [[diethylene glycol]] as a co-initiate in order to lower the viscosity to ease handling and processing (490 OH# sucrose-glycerine polyol, 5,500 cps at 25°C). [[Graft polyol]]s (also called filled polyols or polymer polyols) contain finely dispersed [[Copolymer|styrene-acrylonitrile]], [[acrylonitrile]], or polyurea (PHD) polymer solids chemically grafted to a high molecular weight polyether backbone. They are used to increase the load bearing properties of low-density high-resiliency (HR) foam, as well as add toughness to microcellular foams and cast elastomers. PHD polyols are also used to modify the combustion properties of HR flexible foam. Solids content ranges from 14% to 50%, with 22% and 43% being typical. Initiators such as [[ethylenediamine]] and [[triethanolamine]] are used to make low molecular weight rigid foam polyols that have built-in catalytic activity due to the presence of nitrogen atoms in the backbone. They are used to increase system reactivity and physical property build, and to reduce the friability of rigid foam molded parts. A special class of polyether polyols, [[poly(tetramethylene ether) glycol]]s are made by polymerizing [[tetrahydrofuran]]. They are used in high performance coating and elastomer applications.

Polyester polyols fall into two distinct categories according to composition and application. Conventional polyester polyols are based on virgin raw materials and are manufactured by the direct polyesterification of high-purity diacids and glycols, such as adipic acid and 1,4-butanediol. They are distinguished by the choice of monomers, molecular weight, and degree of branching. While costly and difficult to handle because of their high viscosity, they offer physical properties not obtainable with polyether polyols, including superior solvent, abrasion, and cut resistance. Other polyester polyols are based on reclaimed raw materials. They are manufactured by transesterification ([[glycolysis]]) of recycled [[Polyethylene terephthalate|poly(ethyleneterephthalate)]] (PET) or [[dimethylterephthalate]] (DMT) distillation bottoms with glycols such as diethylene glycol. These low molecular weight, aromatic polyester polyols are used in the manufacture of rigid foam, and bring low cost and excellent flammability characteristics to [[polyisocyanurate]] (PIR) boardstock and polyurethane spray foam insulation.

Specialty polyols include [[polycarbonate]] polyols, [[polycaprolactone]] polyols, [[polybutadiene]] polyols, and [[polysulfide]] polyols. The materials are used in elastomer, sealant, and adhesive applications that require superior weatherability, and resistance to chemical and environmental attack. [[Natural oil polyols]] derived from [[castor oil]] and other [[vegetable oils]] are used to make elastomers, flexible bunstock, and flexible molded foam.
The copolymerization product of chlorotrifluoroethylene or tertafluoroethylene with vinyl ethers which contining hydroxyalkyl vinyl ether produces fluorinated (FEVE) polyols.
Two component fluorinated polyurethane prepared by reacting FEVE fluorinated polyols with polyisocyanate have been applied for make ambient cure paint/coating. Since fluorinated polyurethanes contain high percetage of fluorine-carbon bond which is the strongest bond among all chemical bonds. Fluorinated polyurethanes have excellent resist toward UV, acids, alkali, salts, chemicals, solvents, weathering, corrosion, fugi, and microbial. They are become first choice for high performance coating/paints.

===Chain extenders and cross linkers===
Chain extenders (f=2) and [[cross-link|cross linkers]] (f=3 or greater) are low molecular weight hydroxyl and amine terminated compounds that play an important role in the polymer morphology of polyurethane fibers, elastomers, adhesives, and certain integral skin and microcellular foams. The elastomeric properties of these materials are derived from the phase separation of the hard and soft copolymer segments of the polymer, such that the urethane hard segment domains serve as cross-links between the amorphous polyether (or polyester) soft segment domains. This phase separation occurs because the mainly non-polar, low melting soft segments are incompatible with the polar, high melting hard segments. The soft segments, which are formed from high molecular weight polyols, are mobile and are normally present in coiled formation, while the hard segments, which are formed from the isocyanate and chain extenders, are stiff and immobile. Because the hard segments are covalently coupled to the soft segments, they inhibit plastic flow of the polymer chains, thus creating elastomeric resiliency. Upon mechanical deformation, a portion of the soft segments are stressed by uncoiling, and the hard segments become aligned in the stress direction. This reorientation of the hard segments and consequent powerful hydrogen bonding contributes to high tensile strength, elongation, and tear resistance values.<ref name="Oertel 1985"/><ref>{{cite journal | first=J. | last=Blackwell | coauthors=M.R. Nagarajan and T.B. Hoitink | title=The Structure of the Hard Segments in MDI/diol/PTMA Polyurethane Elastomers | publisher=American Chemical Society | location=Washington, D.C. | year=1981 | issn=0097-6156/81/0172-0179}}</ref><ref>{{cite journal | first=John | last=Blackwell | coauthors=Kenncorwin H. Gardner | title=Structure of the hard segments in polyurethane elastomers | publisher=IPC Business Press | location= | year=1979 | issn=0032-3861/79/010013-05}}</ref><ref>{{cite conference | last=Grillo | first=D.J. | coauthors=Housel, T.L. | title=Physical Properties of Polyurethanes from Polyesters and Other Polyols | booktitle=Polyurethanes '92 Conference Proceedings | publisher=The Society of the Plastics Industry, Inc. | year=1992 | location=New Orleans, LA | accessdate=2007-10-16}}</ref><ref>{{cite conference | last=Musselman | first=S.G. | coauthors=Santosusso, T.M. and Sperling, L.H. | title=Structure Versus Performance Properties of Cast Elastomers | booktitle=Polyurethanes '98 Conference Proceedings | publisher=The Society of the Plastics Industry, Inc. | year=1998 | location=Dallas, TX | accessdate=2007-10-16}}</ref>
The choice of chain extender also determines flexural, heat, and chemical resistance properties. The most important chain extenders are [[ethylene glycol]], [[1,4-butanediol]] (1,4-BDO or BDO), [[1,6-hexanediol]], [[cyclohexane dimethanol]] and [[hydroquinone bis(2-hydroxyethyl) ether]] (HQEE). All of these glycols form polyurethanes that phase separate well and form well defined hard segment domains, and are melt processable. They are all suitable for [[thermoplastic polyurethanes]] with the exception of ethylene glycol, since its derived bis-phenyl urethane undergoes unfavorable degradation at high hard segment levels.<ref name="Gum 1992"/> Diethanolamine and triethanolamine are used in flex molded foams to build firmness and add catalytic activity. Diethyltoluenediamine is used extensively in RIM, and in polyurethane and polyurea elastomer formulations.

{| border="1" cell padding="5" cellspacing="0" style="width: 400px; text-align: center; color: black; background-color: transparent;"
|+'''table of chain extenders and cross linkers'''
<ref>
{{citation
| title = A Guide To Glycols
| work = 117-00991-92HYC
| publisher = The Dow Chemical Company
| year = 1992
| accessdate = 2007-10-23 }}
</ref>
|-
!style="color: black; background-color: #efefef;" colspan="5" | hydroxyl compounds – difunctional molecules
|-
! || MW || s.g. || m.p. °C || b.p. °C
|-
|[[ethylene glycol]] || 62.1 || 1.110 || -13.4 || 197.4
|-
|[[diethylene glycol]] || 106.1 || 1.111 || -8.7 || 245.5
|-
|[[triethylene glycol]] || 150.2 || 1.120 || -7.2 || 287.8
|-
|[[tetraethylene glycol]] || 194.2 || 1.123 || -9.4 || 325.6
|-
|[[propylene glycol]] || 76.1 || 1.032 || [[supercooling|supercools]] || 187.4
|-
|[[dipropylene glycol]] || 134.2 || 1.022 || supercools || 232.2
|-
|[[tripropylene glycol]] || 192.3 || 1.110 || supercools || 265.1
|-
|[[1,3-propanediol]] || 76.1 || 1.060 || -28 || 210
|-
|[[1,3-butanediol]] || 92.1 || 1.005 || - || 207.5
|-
|[[1,4-butanediol]] || 92.1 || 1.017 || 20.1 || 235
|-
|[[neopentyl glycol]] || 104.2 || - || 130 || 206
|-
|[[1,6-hexanediol]] || 118.2 || 1.017 || 43 || 250
|-
|[[1,4-cyclohexanedimethanol]] || - || - || - || -
|-
|[[HQEE]] || - || - || - || -
|-
|[[ethanolamine]] || 61.1 || 1.018 || 10.3 || 170
|-
|[[diethanolamine]] || 105.1 || 1.097 || 28 || 271
|-
|[[methyldiethanolamine]] || 119.1 || 1.043 || -21 || 242
|-
|[[phenyldiethanolamine]] || 181.2 || - || 58 || 228
|-
!style="color: black; background-color: #efefef;" colspan="5" | hydroxyl compounds – trifunctional molecules
|-
! || MW || s.g. || f.p. °C || b.p. °C
|-
|[[glycerol]] || 92.1 || 1.261 || 18.0 || 290
|-
|[[trimethylolpropane]] || - || - || - || -
|-
|[[1,2,6-hexanetriol]] || - || - || - || -
|-
|[[triethanolamine]] || 149.2 || 1.124 || 21 || -
|-
!style="color: black; background-color: #efefef;" colspan="5" | hydroxyl compounds – tetrafunctional molecules
|-
! || MW || s.g. || m.p. °C || b.p. °C
|-
|[[pentaerythritol]] || 136.2 || - || 260.5 || -
|-
|N,N,N',N'-tetrakis (2-hydroxypropyl) ethylenediamine || - || - || - || -
|-
!style="color: black; background-color: #efefef;" colspan="5" | amine compounds – difunctional molecules
|-
! || MW || s.g. || m.p. °C || b.p. °C
|-
|[[diethyltoluenediamine]] || 178.3 || 1.022 || - || 308
|-
|[[dimethylthiotoluenediamine]] || 214.0 || 1.208 || - || -
|-
|}

===Catalysts===
Polyurethane [[catalysts]] can be classified into two broad categories, [[amine]] compounds and [[organometallic]] complexes. They can be further classified as to their specificity, balance, and relative power or efficiency. Traditional amine catalysts have been tertiary amines such as [[triethylenediamine]] (TEDA, also known as 1,4-diazabicyclo[2.2.2]octane or [[DABCO]], an [[Air Products]]'s trade mark), [[dimethylcyclohexylamine]] (DMCHA), and [[dimethylethanolamine]] (DMEA). Tertiary amine catalysts are selected based on whether they drive the urethane (polyol+isocyanate, or gel) reaction, the urea (water+isocyanate, or blow) reaction, or the isocyanate trimerization reaction. Since most tertiary amine catalysts will drive all three reactions to some extent, they are also selected based on how much they favor one reaction over another. For example, [[tetramethylbutanediamine]] (TMBDA) preferentially drives the gel reaction over the blow reaction. On the other hand, both [[pentamethyldipropylenetriamine]] and [[N-(3-dimethylaminopropyl)-N,N-diisopropanolamine]] balance the blow and gel reactions, although the former is more potent than the later on a weight basis. [[1,3,5-(tris(3-dimethylamino)propyl)-hexahydro-s-triazine]] is a trimerization catalyst that also strongly drives the blow reaction. Molecular structure gives some clue to the strength and selectivity of the catalyst. Blow catalysts generally have an ether linkage two carbons away from a tertiary nitrogen. Examples include [[bis-(2-dimethylaminoethyl)ether]] (also known as A-99, formerly a Union Carbide product), and [[N-ethylmorpholine]]. Strong gel catalysts contain alkyl-substituted nitrogens, such as [[triethylamine]] (TEA), 1,8-diazabicyclo[5.4.0]undecene-7 (DBU), and [[pentamethyldiethylenetriamine]] (PMDETA). Weaker gel catalysts contain ring-substituted nitrogens, such as [[benzyldimethylamine]] (BDMA). Trimerization catalysts contain the [[triazine]] structure, or are [[quaternary ammonium salts]]. Two trends have emerged since the late 1980s. The requirement to fill large, complex tooling with increasing production rates has led to the use of blocked catalysts to delay front end reactivity while maintaining back end cure. In the United States, acid- and quaternary ammonium salt-blocked TEDA and bis-(2-dimethylaminoethyl)ether are common blocked catalysts used in molded flexible foam and microcellular integral skin foam applications. Increasing aesthetic and environmental awareness has led to the use of non-fugitive catalysts for vehicle interior and furnishing applications in order to reduce odor, fogging, and the staining of vinyl coverings. Catalysts that contain a hydroxyl group or an active amino hydrogen, such as [[N,N,N'-trimethyl-N'-hydroxyethyl-bis(aminoethyl)ether]] and [[N'-(3-(dimethylamino)propyl)-N,N-dimethyl-1,3-propanediamine]] that react into the polymer matrix can replace traditional catalysts in these applications.<ref>{{cite web | title = Jeffcat Amine Catalysts for the Polyurethane Industry | year = 2006 | url = http://www.huntsman.com/performance_products/Media/JEFFCAT_Catalyst_Trifold_bulletin.pdf | format = pdf | accessdate = 2007-10-23 }}</ref><ref>{{cite web | title = Building quality with Air Products trimerisation catalysts | year = 2003 | url = http://www.airproducts.com/NR/rdonlyres/55C5A72A-D126-4888-9E1A-D24EFBE4AAC1/0/14004004EU.pdf | format = pdf | accessdate = 2007-10-23 }}</ref>

Organometallic compounds based on [[mercury (element)|mercury]], [[lead]], [[tin]] ([[dibutyltin dilaurate]]), [[bismuth]] ([[bismuth octanoate]]), and [[zinc]] are used as polyurethane catalysts. Mercury [[carboxylate]]s, such as [[phenylmercuric neodeconate]], are particularly effective catalysts for polyurethane elastomer, coating and sealant applications, since they are very highly selective towards the polyol+isocyanate reaction. Mercury catalysts can be used at low levels to give systems a long pot life while still giving excellent back-end cure. Lead catalysts are used in highly reactive rigid spray foam insulation applications, since they maintain their potency in low-temperature and high-humidity conditions. Due to their toxicity and the necessity to dispose of mercury and lead catalysts and catalyzed material as hazardous waste in the United States, formulators have been searching for suitable replacements. Since the 1990s, bismuth and zinc carboxylates have been used as alternatives but have short comings of their own. In elastomer applications, long pot life systems do not build green strength as fast as mercury catalyzed systems. In spray foam applications, bismuth and zinc do not drive the front end fast enough in cold weather conditions and must be otherwise augmented to replace lead. Alkyl tin carboxylates, oxides and mercaptides oxides are used in all types of polyurethane applications. For example, [[dibutyltin dilaurate]] is a standard catalyst for polyurethane adhesives and sealants, [[dioctyltin mercaptide]] is used in microcellular elastomer applications, and [[dibutyltin oxide]] is used in polyurethane paint and coating applications. Tin mercaptides are used in formulations that contain water, as tin carboxylates are susceptible to degradation from hydrolysis.<ref>{{citation | title = FOMREZ Specialty Tin Catalysts for Polyurethane Applications | work = 120-074-10 | publisher = Crompton Corporation | date = 2001-01 | accessdate = 2007-10-23 }}</ref><ref>{{citation | title = FOMREZ Specialty Tin Catalysts for Polyurethane Applications (leaflet insert) | work = 120-075-10 | publisher = Crompton Corporation | date = 2001-01 | accessdate = 2007-10-23 }}</ref>

===Surfactants===
[[Surfactants]] are used to modify the characteristics of both foam and non-foam polyurethane polymers. They take the form of polydimethylsiloxane-polyoxyalkylene block copolymers, [[silicone]] oils, [[nonylphenol]] ethoxylates, and other organic compounds. In foams, they are used to emulsify the liquid components, regulate cell size, and stabilize the cell structure to prevent collapse and sub-surface voids. In non-foam applications they are used as air release and anti-foaming agents, as wetting agents, and are used to eliminate surface defects such as pin holes, orange peel, and sink marks.

==Production==
The main polyurethane producing reaction is between a [[isocyanate|diisocyanate]] ([[aromatic]] and [[aliphatic]] types are available) and a [[polyol]], typically a [[polypropylene glycol]] or [[polyester polyol]], in the presence of [[catalyst]]s and materials for controlling the [[cell structure]], ([[surfactant]]s) in the case of foams. Polyurethane can be made in a variety of densities and hardnesses by varying the type of [[monomer]](s) used and adding other substances to modify their characteristics, notably [[density]], or enhance their performance. Other additives can be used to improve the fire performance, stability in difficult chemical environments and other properties of the polyurethane products.

[[Image:UVDistressedFlexMoldedFoam800x600.png|thumb|150px|Polyurethane foam made with an aromatic isocyanate, which has been exposed to UV light. Readily apparent is the discoloration that occurs over time. This particular foam piece is approximately four inches wide and 1-1/2 inches thick.]]Though the properties of the polyurethane are determined mainly by the choice of polyol, the diisocyanate exerts some influence, and must be suited to the application. The cure rate is influenced by the functional group reactivity and the number of functional isocyanate groups. The mechanical properties are influenced by the functionality and the molecular shape. The choice of diisocyanate also affects the stability of the polyurethane upon exposure to light. Polyurethanes made with aromatic diisocyanates yellow with exposure to light, whereas those made with aliphatic diisocyanates are stable.<ref>{{cite book | first=David | last=Randall | coauthors=Lee, Steve | title=The Polyurethanes Book | publisher=Wiley | location=New York | year=2002 | isbn=0-470-85041-8}}</ref>

Softer, [[elasticity (solid mechanics)|elastic]], and more flexible polyurethanes result when linear difunctional polyethylene glycol segments, commonly called [[polyether polyol]]s, are used to create the [[Carbamate|urethane]] links. This strategy is used to make [[spandex]] elastomeric fibers and soft rubber parts, as well as foam rubber. More rigid products result if polyfunctional polyols are used, as these create a three-dimensional cross-linked structure which, again, can be in the form of a low-density foam.

An even more rigid foam can be made with the use of specialty trimerization catalysts which create cyclic structures within the foam matrix, giving a harder, more thermally stable structure, designated as polyisocyanurate foams. Such properties are desired in rigid foam products used in the construction sector.

Careful control of viscoelastic properties — by modifying the catalysts and polyols used —can lead to memory foam, which is much softer at skin temperature than at room temperature.

There are then two main foam variants: one in which most of the foam bubbles (cells) remain closed, and the gas(es) remains trapped, the other being systems which have mostly open cells, resulting after a critical stage in the foam-making process (if cells did not form, or became open too soon, foam would not be created).
This is a vitally important process: if the flexible foams have closed cells, their softness is severely compromised, they become pneumatic in feel, rather than soft; so, generally speaking, flexible foams are required to be open-celled.

The opposite is the case with most rigid foams. Here, retention of the cell gas is desired since this gas (especially the fluorocarbons referred to above) gives the foams their key characteristic: high thermal insulation performance.

A third foam variant, called [[microcellular foam]], yields the tough elastomeric materials typically experienced in the coverings of car steering wheels and other interior automotive components.

==Health and safety==
Fully reacted polyurethane polymer, CAS # 9009-54-5 ([[CAS registry number]]), is chemically [[wikt:inert|inert]].<ref>Dernehl CU. (1966). [http://journals.lww.com/joem/Citation/1966/02000/Health_Hazards_Associated_with_Polyurethane_Foams.2.aspx Health Hazards Associated with Polyurethane]. ''Journal of Occupational and Environmental Medicine''.</ref> Foams In the United States, no exposure limits have been established by OSHA ([[Occupational Safety and Health Administration]]) or ACGIH ([[American Conference of Governmental Industrial Hygienists]]). It is not regulated by OSHA for carcinogenicity. Polyurethane polymer is a combustible solid and will ignite if exposed to an open flame for a sufficient period of time. It begins breakdown at approximately 240C (464F), a temperature which can be reached if the material is cut with a power saw rather than a shearing-type tool.<ref>Safety and Health Committee, National Stone, Sand, and Gravel Association. [http://www.nssga.org/safetyhealth/polyurethaneexposure0204.pdf Health Alert: Polyurethane exposure].</ref> Decomposition product can include [[isocyanate]]s, carbon monoxide, oxides of nitrogen, and [[hydrogen cyanide]]. Firefighters should wear self-contained breathing apparatus in enclosed areas. Polyurethane polymer dust can cause irritation to the eyes and lungs. Proper hygiene controls and [[personal protective equipment]] (PPE), such as gloves, dust masks, respirators, mechanical ventilation, and protective clothing and eye wear should be used.

Liquid resin blends and [[isocyanate]]s may contain hazardous or regulated components. They should be handled in accordance with manufacturer recommendations found on product labels, and in MSDS ([[Material Safety Data Sheet]]) and product technical literature. Isocyanates are known skin and respiratory sensitizers, and proper engineering controls should be in place to prevent exposure to isocyanate liquid and vapor.

In the United States, additional health and safety information can be found through organizations such as the Polyurethane Manufacturers Association (PMA) and the Center for the Polyurethanes Industry (CPI), as well as from polyurethane system and raw material manufacturers. In Europe, health and safety information is available from ISOPA<ref>http://www.isopa.org ISOPA</ref>, the European Diisocyanate and Polyol Producers Association. Regulatory information can be found in the [[Code of Federal Regulations]] Title 21 (Food and Drugs) and Title 40 (Protection of the Environment).

==Manufacturing==

The methods of manufacturing polyurethane finished goods range from small, hand pour piece-part operations to large, high-volume bunstock and boardstock production lines. Regardless of the end-product, the manufacturing principle is the same: to meter the liquid isocyanate and resin blend at a specified stoichiometric ratio, mix them together until a homogeneous blend is obtained, dispense the reacting liquid into a mold or on to a surface, wait until it cures, then demold the finished part.

===Dispense Equipment===

Although the capital outlay can be high, it is desirable to use a meter-mix or dispense unit for even low-volume production operations that require a steady output of finished parts. Dispense equipment consists of material holding (day) tanks, metering pumps, a mix head, and a control unit. Often, a conditioning or heater-chiller unit is added to control material temperature in order to improve mix efficiency, cure rate, and to reduce process variability. Choice of dispense equipment components depends on shot size, throughput, material characteristics such as viscosity and filler content, and process control. Material day tanks may be single to hundreds of gallons in size, and may be supplied directly from drums, IBCs (intermediate bulk containers, such as totes), or bulk storage tanks. They may incorporate level sensors, conditioning jackets, and mixers. Pumps can be sized to meter in single grams per second up to hundreds of pounds per minute. They can be rotary, gear, or piston pumps, or can be specially hardened lance pumps to meter liquids containing highly abrasive fillers such as [[wollastonite]].

<gallery>
Image:HighPressureDispenseUnit800x600.png|A high pressure polyurethane dispense unit, showing control panel, high pressure pump, integral day tanks, and hydraulic drive unit.
Image:HighPressureLHeadFront600x800.png|A high pressure mix head, showing simple controls. Front view.
Image:HighPressureLHeadRear600x800.png|A high pressure mix head, showing material supply and hydraulic actuator lines. Rear view.
</gallery>

The pumps can drive low-pressure (10 to 30 bar) or high-pressure (125 to 200 bar) dispense systems. Mix heads can be simple static mix tubes, rotary element mixers, low-pressure dynamic mixers, or high-pressure hydraulically actuated direct impingement mixers. Control units may have basic on/off – dispense/stop switches, and analogue pressure and temperature gages, or may be computer controlled with flow meters to electronically calibrate mix ratio, digital temperature and level sensors, and a full suite of statistical process control software. Add-ons to dispense equipment include nucleation or gas injection units, and third or fourth stream capability for adding pigments or metering in supplemental additive packages.

<gallery>
Image:LowPressureMixHead600x800.png|A low pressure mix head with calibration chamber installed, showing material supply and air actuator lines.
Image:LowPressureMixChamberComponents800x600.png|Low pressure mix head components, including mix chambers, conical mixers, and mounting plates.
Image:LowPressure5GallonDayTanks800x600.png|5-gallon (20-liter) material day tanks for supplying a low pressure dispense unit.
</gallery>

===Tooling===

Distinct from pour-in-place, bun and boardstock, and coating applications, the production of piece parts requires some type of tooling to contain and form the reacting liquid. The choice of mold making material is dependent on the expected number of uses to end-of-life (EOL), molding pressure, flexibility, and heat transfer characteristics. RTV silicone is used for tooling that has an EOL in the thousands of parts. It is typically used for molding rigid foam parts, where the ability to stretch and peel the mold around undercuts is needed. The heat transfer characteristic of RTV silicone tooling is poor. High-performance flexible polyurethane elastomers are also used in this way. Epoxy, metal-filled epoxy, and metal-coated epoxy is used for tooling that has an EOL in the tens-of-thousands of parts. It is typically used for molding flexible foam cushions and seating, integral skin and microcellular foam padding, and shallow-draft RIM bezels and fascia. The heat transfer characteristic of epoxy tooling is fair; the heat transfer characteristic of metal-filled and metal-coated epoxy is good. Copper tubing can be incorporated into the body of the tool, allowing hot water to circulate and heat the mold surface. Aluminum is used for tooling that has an EOL in the hundreds-of-thousands of parts. It is typically used for molding microcellular foam gasketing and cast elastomer parts, and is milled or extruded into shape. Mirror finish stainless steel is used for tooling that imparts a glossy appearance to the finished part. The heat transfer characteristic of metal tooling is excellent. Finally, molded or milled polypropylene is used to create low-volume tooling for molded gasket applications. Instead of many expensive metal molds, low-cost plastic tooling can be formed from a single metal master, which also allows greater design flexibility. The heat transfer characteristic of polypropylene tooling is poor, which must be taken into consideration during the formulation process.

==Uses==

Polyurethane products have many uses. Over three quarters of the global consumption of polyurethane products is in the form of foams, with flexible and rigid types being roughly equal in market size.
In both cases, the foam is usually behind other materials: flexible foams are behind upholstery fabrics in commercial and domestic furniture; rigid foams are inside the metal and plastic walls of most [[refrigerator]]s and freezers, or behind paper, metals and other surface materials in the case of thermal [[Thermal insulation|insulation]] panels in the construction sector. Its use in garments is growing: for example, in lining the cups of brassieres. Polyurethane is also used for moldings which include door frames, columns, balusters, window headers, pediments, medallions and rosettes.


{| class="toccolours" border="1" style="clear: both; margin: 0.5em; margin-left: 0; border-collapse: collapse;"
| align="center" style="letter-spacing: 1px; color: black; background-color: #efefef;" | '''{{{name|characteristics of polyurethane materials}}}'''
|-
| align="center" colspan="1" bgcolor="white" style="padding: 0.5em;" | [[Image:Purgrid.png|640px]]
|-
|}

Polyurethane is also used in the concrete construction industry to create [[formliner]]s. Polyurethane formliners serves as a mold for concrete, creating a variety of textures and art.

The precursors of expanding polyurethane foam are available in many forms, for use in insulation, sound deadening, flotation, industrial coatings, packing material, and even cast-in-place upholstery padding. Since they adhere to most surfaces and automatically fill voids, they have become quite popular in these applications.

The following table shows how polyurethanes are used (US data from 2004):<ref>{{cite web |url=http://www.polyurethane.org/s_api/bin.asp?CID=867&DID=3746&DOC=FILE.PDF |title=The Socio-Economic Impact of Polyurethanes in the United States from the American Chemistry Council |accessdate=2007-09-28 |last= |first= |coauthors= |month=February | year=2004 |work= |publisher=The Polyurethanes Recycle and Recovery Council (PURRC), a committee of the [http://www.polyurethane.org/s_api/index.asp Center for the Polyurethanes Industry]|format=PDF}}</ref>.

{| class="wikitable"
|-
! Application
! Amount of polyurethane used
(millions of pounds)
! Percentage of total
|-
| Building & Construction
| 1,459
| 26.8%
|-
| Transportation
| 1,298
| 23.8%
|-
| Furniture & Bedding
| 1,127
| 20.7%
|-
| Appliances
| 278
| 5.1%
|-
| Packaging
| 251
| 4.6%
|-
| Textiles, Fibers & Apparel
| 181
| 3.3%
|-
| Machinery & Foundry
| 178
| 3.3%
|-
| Electronics
| 75
| 1.4%
|-
| Footwear
| 39
| 0.7%
|-
| Other uses
| 558
| 10.2%
|-
| Total
| 5,444
| 100.0%
|}

In 2007, the global consumption of polyurethane raw materials was above 12 million metric tons, the average annual growth rate is about 5%.<ref>G. Avar, Polyurethanes (PU), Kunststoffe international 10/2008, 123-127.</ref>

===Varnish===
Polyurethane materials are commonly formulated as [[paint]]s and [[varnish]]es for [[Wood finishing|finishing]] coats to protect or seal wood. This use results in a hard, abrasion-resistant, and durable coating that is popular for [[hardwood]] floors, but considered by some to be difficult or unsuitable for finishing furniture or other detailed pieces. Relative to oil or shellac varnishes, polyurethane varnish forms a harder film which tends to de-laminate if subjected to heat or shock, fracturing the film and leaving white patches. This tendency increases when it is applied over softer woods like [[pine]]. This is also in part due to polyurethane's lesser penetration into the wood. Various priming techniques are employed to overcome this problem, including the use of certain oil varnishes, specified "dewaxed" [[shellac]], clear penetrating [[epoxy]], or "oil-modified" polyurethane designed for the purpose. Polyurethane varnish may also lack the "hand-rubbed" lustre of [[drying oil]]s such as [[Linseed oil|linseed]] or [[tung oil]]; in contrast, however, it is capable of a much faster and higher "build" of film, accomplishing in two coats what may require many applications of oil. Polyurethane may also be applied over a straight oil finish, but because of the relatively slow curing time of oils, the presence of volatile byproducts of curing, and the need for extended exposure of the oil to oxygen, care must be taken that the oils are sufficiently cured to accept the polyurethane.

Unlike [[drying oil]]s and [[alkyd]]s which [[Curing (chemistry)|cure]], after evaporation of the solvent, upon reaction with [[oxygen]] from the air, polyurethane coatings cure after [[evaporation]] of the [[solvent]] by a variety of reactions of [[chemical]]s within the original mix, or by reaction with [[moisture]] from the air. Certain products are "hybrids" and combine different aspects of their parent components. "Oil-modified" polyurethanes, whether water-borne or solvent-borne, are currently the most widely used wood floor finishes.

Exterior use of polyurethane varnish may be problematic due to its susceptibility to deterioration through [[ultra-violet]] light exposure. It must be noted, however, that all clear or transluscent varnishes, and indeed all [[film]]-[[polymer]] coatings (i.e., [[paint]], [[stain]], [[epoxy]], synthetic [[plastic]], etc.) are susceptible to this damage in varying degrees. [[Pigment]]s in [[paint]]s and [[stain]]s protect against UV damage, while [[UV]]-absorbers are added to polyurethane and other varnishes (in particular "[[spar]]" [[varnish]]) to work against [[UV]] damage. Polyurethanes are typically the most resistant to water exposure, high humidity, temperature extremes, and fungus or mildew, which also adversely affect varnish and paint performance.

===Wheels===
Polyurethane is also used in making solid [[tires]]. Industrial applications include [[forklift]] drive and load wheels, grocery cart and, rollercoaster wheels. Modern [[roller blading]] and [[skateboard]]ing became economical only with the introduction of tough, abrasion-resistant polyurethane parts, helping to usher in the permanent popularity of what had once been an obscure 1960s craze. The durability of polyurethane wheels allowed the range of tricks and stunts performed on [[skateboards]] to expand considerably. Other constructions have been developed for pneumatic tires, and microcellular foam variants are widely used in tires on wheelchairs, bicycles and other such uses. These latter foam types are also widely encountered in car steering wheels and other interior and exterior automotive parts, including bumpers and fenders.


===Furniture===
Open cell flexible polyurethane foam (FPF) is made by mixing [[polyols]], [[diisocyanate]]s, catalysts, auxiliary blowing agents and other additives and allowing the resulting foam to rise freely. Most FPF is manufactured using continuous processing technology and also can be produced in batches where relatively small blocks of foam are made in open-topped molds, boxes, or other suitable enclosurers. The foam is then cut to the desired shape and size for use in a variety of furniture and furnishings applications.

Applications for flexible polyurethane foam include [[upholstered]] [[furniture]] cushions, automotive seat cushions and interior trim, [[carpet cushion]], and [[mattress]] padding and solid-core mattress cores.

Flexible polyurethane foam is a recyclable product.
<ref>http://www.pfa.org/intouch/index.html</ref>

===Automobile seats===
Flexible and semi-flexible polyurethane foams are used extensively for interior components of [[automobile]]s, in seats, headrests, armrests, roof liners, [[dashboard]]s and instrument panels.

[[Image:Molded polyurethane foam.JPG|thumb|150px|Polyurethane foam in the lower half of the mold in which it was made. When assembled into a car seat, this foam makes up the seat back. The forward-facing part of the seat back is the surface of the foam which is face-down in the mold. The two holes in the foam at the top of the picture are for the headrest posts.]][[Image:Foam seat back.JPG|thumb|150px|Foam after removal from the mold.]]
Polyurethanes are used to make automobile seats in a remarkable manner. The seat manufacturer has a [[Molding (process)|mold]] for each seat model. The mold is a closeable "clamshell" sort of structure that will allow quick casting of the seat cushion, so-called molded flexible foam, which is then upholstered after removal from the mold.

It is possible to combine these two steps, so-called ''in-situ'', foam-in-fabric or direct moulding. A complete, fully-assembled seat cover is placed in the mold and held in place by vacuum drawn through small holes in the mold. Sometimes a thin pliable plastic film backing on the fabric is used to help the vacuum work more effectively. The metal seat frame is placed into the mold and the mold closed. At this point the mold contains what could be visualized as a "hollow seat", a seat fabric held in the correct position by the vacuum and containing a space with the metal frame in place.

Polyurethane chemicals are injected by a mixing head into the mold cavity. Then the mold is held at a preset reaction temperature until the chemical mixture has foamed, filled the mold, and formed a stable soft foam. The time required is two to three minutes, depending on the size of the seat and the precise formulation and operating conditions. Then the mold is usually opened slightly for a minute or two for an additional cure time, before the fully upholstered seat is removed.

===Houses, sculptures, and decorations===
The walls and ceiling (not just the insulation) of the futuristic [[Xanadu House]] were built out of polyurethane foam. Domed ceilings and other odd shapes are easier to make with foam than with wood. Foam was used to build oddly-shaped buildings, statues, and decorations in the Seuss Landing section of the [[Islands of Adventure]] theme park. Speciality rigid foam manufactures sell foam that replace wood in carved sign and 3D-topography industries. PU foam is also used as a [[thermal insulator]] in many houses.

Polyurethane resin is used as an aesthetic flooring material. Being seamless and water resistant, it is gaining interest for use in (modern) interiors, especially in Western Europe.

<gallery>
Image:Polyurethane insulator.jpg|Polyurethane being used as an insulator in house construction.
Image:Seamless_Resin_Floors.jpg|Polyurethane used as a flooring material.
Image:Seamless_Resin_Floors_2.jpg|Being poured as a liquid after which it hardens out, polyurethane is a floor material that can be applied seamlessly.
</gallery>

===Construction sealants and firestopping===
Polyurethane sealants are available in one, two and three part systems, and in cartridges, buckets or drums. Polyurethane sealants are used to fill gaps thereby preventing air and water leakage. They are also used in conjunction with inorganic [[Thermal insulation|insulation]], such as [[Mineral wool|rockwool]] or ceramic fibres, for [[firestop]]ping. Firestops can thwart [[smoke]] and [[Fire test|hose-stream]] passage.

===Surfboards===
Some [[surfboard]]s are made with a rigid polyurethane core. A rigid foam blank is molded, shaped to specification, then covered with fiberglass cloth and polyester resin.

===Rigid-hulled boats===
Some boat hulls have a rigid polyurethane foam core sandwiched between fiberglass skins. The foam provides strength, buoyancy, and sound deadening.

===Inflatable boats===
Some raft manufacturers use urethane for the construction of inflatable boats. AIRE uses urethane membrane material as an air-retentive bladder inside a PVC shell, whereas SOTAR uses urethane membrane materials as a coating on some boats. Maravia uses a liquid urethane material which is spray-coated over PVC to enhance air retention and increase abrasion resistance.

===Tennis grips===
Polyurethane has been used to make several Tennis Overgrips such as Yonex Supergrasp, Wilson Pro Overgrip and many other grips. These grips are highly stretchable to ensure the grip wraps neatly around the racquet's handle.

===Electronic components===
Often electronic components are protected from environmental influence and mechanical shock by [[resin dispensing|enclosing]] them in polyurethane. Typically polyurethanes are selected for the excellent abrasion resistances, good electrical properties, excellent adhesion, impact strength,and low temperature flexibility. The disadvantage of polyurethanes is the limited upper service temperature (typically 250 °F (121 °C)). In production the electronic manufacture would purchase a two part urethane (resin and catalyst) that would be mixed and poured onto the circuit assembly (see [[Resin dispensing]]). In most cases, the final circuit board assembly would be unrepairable after the urethane has cured. Because of its physical properties and low cost, polyurethane encapsulation (potting) is a popular option in the automotive manufacturing sector for automotive circuits and sensors.

===Adhesives===
Polyurethane is used as an [[adhesive]], especially as a [[woodworking glue]]. Its main advantage over more traditional wood glues is its water resistance. It was introduced in the general North American market in the 1990s as ''[[Gorilla Glue]]'' and ''Excel'', but has been used much longer in Europe.

On the way to a new and better glue for [[bookbinder]]s, a new adhesive system was introduced for the first time in 1985. The base for this system is polyether or polyester, whereas polyurethane (PUR) is used as prepolymer. Its special feature is the coagulation at room temperature and the reacting to moisture.

First generation (1988)
* Low starting solidity
* High viscosity
* Cure time >3 days

Second generation (1996)
* Low starting solidity
* High viscosity
* Cure time <3 days

Third generation (2000)
* Good starting solidity
* Low viscosity
* Cure time between 6 and 16 hours

Fourth generation (present)
* Good starting solidity
* Very low viscosity
* Cure reached within a few seconds due to dual-core systems

Advantages of polyurethane glue in the bookbinding industry:

* PUR is real wonder compared to hotmelt and cold glue. Because of the missing moisture in the glue, papers with wrong grain direction can be processed without problems. Even printed and supercalandered paper can be bound without problems. It is the most economical glue with an application thickness of theoretical 0.01 mm. But in reality it is not possible to apply less than 0.03 mm.

* PUR glue is very weather-proof and stable at temperatures from -40 °C to 100 °C.{{Citation needed|date=February 2008}}

===Watch-band wrapping===
Polyurethane is used as a black wrapping for timepiece bracelets over the main material which is generally stainless steel. It is used for comfort, style, and durability.

===Abrasion resistance===
Thermoset polyurethanes are also used as a protective coating against abrasion. Cast polyurethane over materials such as steel will absorb particle impact more efficiently. Polyurethanes have been proven to last in excess of 25 years in abrasive environments where non-coated steel would erode in less than 8 years. Polyurethanes are used in industries such as:

* Mining and mineral processing
* Aggregate
* Transportation
* Concrete
* Paper processing
* Power
* Inflatable boat manufacture

===Filling of spaces and cavities===

Two [[Binary liquid]]s, one of which is a polyurethane (either T6 or 16), when mixed and [[Aeration|aerated]], expand into a hard, space-filling [[aerosolid]].

===Textiles===
A thin film of polyurethane is added to a polyester weave to create [[polyurethane laminate]] (PUL), which is used for its waterproof and windproof properties in outerwear, diapers, shower curtains, and so forth. PU is used in some cutting-edge swimsuits to provide buoyancy for competitive swimmers. There are restrictions as the buoyancy enhances swimming performance.{{Citation needed|date=August 2009}}

A still more popular use of polyurethane in textiles is in the form of [[spandex]], also known as elastane or by DuPont's brand name Lycra. Polyurethane fibers in the form of spandex can stretch up to 600% and still return to their original shape. Spandex is spun with other fibers, such as cotton, nylon, or polyester, to create stretchable fibers essential for clothing for both sports and fashion.<ref>{{Cite journal
| authorlink = Marc Reisch
| title = What's That Stuff?
| journal = Chemical & Engineering News
| volume = 77
| pages = 7
| date = February 15, 1999
| issn = 0009-2347
| url =http://pubs.acs.org/cen/whatstuff/stuff/7707scitek4.html }}</ref>

==Testing==
===Effects of visible light===
Polyurethanes, especially those made using [[aromatic]] isocyanates, contain [[chromophores]] which interact with light. This is of particular interest in the area of polyurethane coatings, where [[light]] stability is a critical factor and is the main reason that [[aliphatic]] isocyanates are used in making polyurethane coatings. When PU foam, which is made using aromatic isocyanates, is exposed to visible light it discolors, turning from off-white to yellow to reddish brown. It has been generally accepted that apart from yellowing, visible light has little effect on foam properties.<ref>{{cite web|url=http://www.foamex.com/pdfs/Discoloration%20Info%20Sheet.pdf|format=PDF| title=Discoloration of polyurethane foam|publisher=Foamex Information sheet|accessdate=2008-01-26}}</ref><ref>{{cite journal |last=Valentine |first=C |authorlink= |coauthors=Craig, T.A.; Hager, S.L |year=1993 |month= |title=Inhibition of the Discoloration of Polyurethane Foam Caused by Ultraviolet Light |journal=J. Cellular Plastics |volume=29 |issue= |pages=569–590 |id= |url= |accessdate= 2008-01-26 |quote=|doi=10.1177/0021955X9302900605 }}</ref> This is especially the case if the yellowing happens on the outer portions of a large foam, as the deterioration of properties in the outer portion has little effect on the overall bulk properties of the foam itself.

It has been reported that exposure to visible light can affect the variability of some physical property test results.<ref>{{cite conference |first=G. Ron |last=Blair |authorlink= |coauthors=Bob Dawe,Jim McEvoy, Roy Pask, Marcela Rusan de Priamus, Carol Wright |title=The Effect of Visible Light on the Variability of Flexible Foam Compression Sets |booktitle= |pages= |publisher=Center for the Polyurethane Industry |year=2007 |location=Orlando, Florida |url= |accessdate=2008-01-26 |id= }}</ref> Increasing exposure time and/or light intensity during the storage of foam samples under ambient laboratory conditions increased the amount of permanent set induced in some compression set tests (the samples did not fully return to their original size and/or shape). Variability resulted from uncontrolled light exposure of cut samples prior to being compressed. Other foam properties were not substantively affected. It was recommended that specimen preparation and testing be done rapidly to minimize variation in results or if specimens are prepared but not tested for a week or more, that the samples should be protected from light exposure.

Higher-energy [[UV]] radiation promotes chemical reactions in foam, some of which are detrimental to the foam structure.<ref>{{cite journal |last=Newman |first=C.R. |authorlink= |coauthors= Forciniti, D. |year=2001 |month= |title=Modeling the Ultraviolet Photodegradation of Rigid Polyurethane Foams |journal=Ind. Eng. Chem. Res. |volume=40 |issue= |pages=3336–3352 |id= |url= |accessdate= 2008-01-26 |quote=|doi=10.1021/ie0009738 }}</ref>

==See also==
* [[Passive fire protection]]
* [[Penetrant]]
* [[Silicone]]

==References==
{{Reflist|2}}

==External links==
{{Commons category|Polyurethane foam}}
* [http://www.polyurethane.org/s_api/index.asp Center for the Polyurethanes Industry]: information for EH&S issues related to polyurethanes
* [http://www.pfa.org Polyurethane Foam Association]: Information regarding flexible polyurethane foam (FPF) as used in home furnishings cushioning, automotive interiors and packaging
* [http://www.pslc.ws/macrog/uresyn.htm Polyurethane synthesis]
* [http://www.polyurethanes.org Polyurethanes Information Portal]: Industry information website describing the applications and benefits of polyurethane
*[http://www.pu-magazine.com/ PU Magazine International]: Information for the Polyurethanes Industry

[[Category:Polyurethanes]]
[[Category:Plastics]]
[[Category:Wood finishing materials]]
[[Category:Building insulation materials]]
[[Category:Adhesives]]
[[Category:Coatings]]

[[ar:بولي يوريثان]]
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[[ko:폴리우레탄]]
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[[nl:Polyurethaan]]
[[ja:ポリウレタン]]
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Aerosol spray dispenser

2009-12-30T23:31:02Z

Fluonova: /* Packaging */ add 2K aerosol principle

[[Image:Aerosol.png|thumb|right|250px|Aerosol spray can]]
'''Aerosol spray''' is a type of dispensing system which creates an [[Particulate|aerosol]] mist of liquid particles. This is used with a [[spray can|can]] or [[bottle]] that contains a liquid under pressure. When the container's valve is opened, the liquid is forced out of a small hole and emerges as an [[Particulate|aerosol]] or [[mist]]. As gas expands to drive out the payload, some propellant evaporates inside the can to maintain an even pressure. Outside the can, the droplets of propellant evaporate rapidly, leaving the payload suspended as very fine particles or droplets. Typical liquids dispensed in this way are [[insecticide]]s, [[deodorant]]s and [[aerosol paint|paint]]s. An [[atomization|atomizer]] is a similar device that is pressurised by a hand-operated pump rather than by stored gas.

== History ==
[[Image:Aerosol 1943.jpg|thumb|The aerosol spray canister invented by [[USDA]] researchers, Lyle Goodloe and William Sullivan.]]

The concepts of aerosol probably goes as far back as 1790.<ref name= Bellis> Bellis, Mary [http://inventors.about.com/od/astartinventions/a/aerosol.htm The History of Aerosol Spray Cans]</ref> The first aerosol spray can was invented in [[Oslo]] in November 23, 1927 by [[Erik Rotheim]], a [[Norway|Norwegian]] chemical engineer.<ref name= Bellis/> The patent was sold to a US company for 100,000 [[Norwegian krone|Norwegian kroner]].<ref>{{cite news|url=http://www.aftenposten.no/viten/article492297.ece|title=Sprayboksens far er norsk|last=Kvilesjø|first=Svend Ole|date=17 February 2003|work=Aftenposten|language=Norwegian|accessdate=6 February 2009}}</ref> The Norwegian Post Office celebrated the invention by issuing a stamp in 1998.<ref>[http://cache.aftenposten.no/multimedia/archive/00101/FRIMERKE_101049a.jpg Image of the Norway Postage stamp]</ref>

In 1939, American Julian S. Kahn received a patent for a disposable spray can<ref>Carlisle, Rodney (2004). ''Scientific American Inventions and Discoveries'', p.402. John Wiley & Songs, Inc., New Jersey. ISBN 0471244104.</ref>, but the product remained largely undeveloped. It was not until 1941 that the aerosol spray can was first put to good use by [[United States|Americans]] Lyle Goodhue and William Sullivan, who are credited as the inventors of the modern spray can.<ref name=McGrath>{{cite book |author=Kimberley A. McGrath (Editor), Bridget E. Travers (Editor) |title=World of Invention "Summary"| url= http://www.bookrags.com/research/aerosol-spray-woi/ |publisher=Thomson Gale |location=Detroit|year= |pages= |isbn=0-7876-2759-3 |oclc= |doi=}}</ref> Their design of a refillable spray can dubbed the “bug bomb”, was patented in 1943, and is the ancestor of many popular commercial spray products. Pressurized by liquefied gas, which gave it propellant qualities, the small, portable can enabled soldiers to defend against [[malaria]]-carrying [[Anopheles|mosquitoes]] by spraying inside [[tent]]s in the [[Pacific War|Pacific]] during [[World War II]].<ref>Core, Jim, Rosalie Marion Bliss, and Alfredo Flores. (September 2005) [http://ars.usda.gov/is/ar/archive/sep05/vector0905.htm?pf=1 "ARS Partners With Defense Department To Protect Troops From Insect Vectors"]. ''Agricultural Research Magazine''Vol. 53, No. 9 .</ref> In 1948, three companies were granted licenses by the United States government to manufacture aerosols. Two of the three companies still manufacture aerosols to this day, Chase Products Company and Claire Manufacturing. The "crimp-on valve", used to control the spray was developed in 1949 by [[Bronx]] machine shop proprietor [[Robert Abplanalp|Robert H. Abplanalp]].<ref name=McGrath/>

== Technology (aerosol propellants) ==

If aerosol cans were simply filled with compressed gas, it would either need to be at a dangerously high pressure or the amount of gas in the can would be small, and would rapidly deplete. Usually the gas is the [[vapor]] of a liquid with [[boiling point]] slightly lower than [[room temperature]]. This means that inside the pressurised can, the vapor can exist in [[thermodynamic equilibrium|equilibrium]] with its bulk liquid at a pressure that is higher than [[atmospheric pressure]] (and able to expel the payload), but not dangerously high. As gas escapes, it is immediately replaced by evaporating liquid. Since the propellant exists in liquid form in the can, it should be miscible with the payload or dissolved in the payload.

[[Chlorofluorocarbon]]s (CFCs) were once often used, but since the [[Montreal Protocol]] came into force in 1989, they have been replaced in nearly every country due to the negative effects CFCs have on Earth's [[ozone layer]]. The most common replacements are mixtures of volatile [[hydrocarbon]]s, typically [[propane]], n-[[butane]] and [[isobutane]]. [[Dimethyl ether]] (DME) and [[methyl ethyl ether]] are also used. All these have the disadvantage of being flammable. [[Nitrous oxide]] and [[carbon dioxide]] are also used as propellants to deliver foodstuffs (for example, [[whipped cream]] and [[cooking spray]]). Medicinal aerosols such as [[asthma inhaler]]s use [[hydrofluoroalkanes]] (HFA): either [[HFA 134a]] (1,1,1,2,-tetrafluoroethane) or HFA 227 (1,1,1,2,3,3,3-heptafluoropropane) or combinations of the two.

==Packaging==
[[Image:Aerosol tops 6.svg|thumb|223px|A typical paint valve system will have a "[[Gender of connectors and fasteners|female]]" valve, the stem being part of the top actuator. The valve can be preassembled with the valve cup and installed on the can as one piece, prior to pressure-filling. The actuator is added later.]]
Modern aerosol spray products have three major parts; the can, the valve and the actuator or button. The can is most commonly lacquered [[tinplate]] (steel with a layer of tin) and may be made of two or three pieces of metal crimped together. [[Aluminium]] cans are also common and are generally used for more expensive products. The valve is crimped to the rig of the can, the design of this component is important in determining the spray rate. The actuator is depressed by the user to open the valve; the shape and size of the nozzle in the actuator controls the spread of the aerosol spray.

Packaging that uses a piston barrier system is often used for highly viscous products such as post-foaming hair gels, thick creams and lotions, food spreads and industrial products and sealants. The main benefit of the piston barrier system is that is assures separation of the product from the propellant, maintaining the purity and integrity of the formulation throughout its consumer lifespan. The piston barrier system also provides a controlled and uniform product discharge rate with minimal product retention and is economical.

Another type of dispensing system is the bag-in-can system (or BOV “bag on valve”). This system separates the product from the pressurizing agent with a hermetically-sealed, multi-layered laminated pouch, which maintains complete formulation integrity so only pure product is dispensed. Among its many benefits, the bag-in-can system extends a product’s shelf life. The bag-on-valve, or ABS, is widely used by sun care marketers for its benefits: all-attitude (360-degree) dispensing, quiet and non-chilling discharge. This bag-in-can system is also used in the packaging of pharmaceutical, industrial, household, pet care and other products that require complete separation between the product and the propellant.

A new development is 2K (two component) aerosol. A 2K aerosol device has main component stored in main chamber and a second component stored in an assesory container. When applicator activates the 2K aerosol by break the accessory container, the two components mix. The 2K aerosol can has the advantage for delivery reactive mixture. For example, 2K reactive mixture can use low molecular weight monomer, oligomer, and functional low molecular polymer to make final cross-linked high molecular weight polymer. 2K aerosol can increase solid contents and deliver high performence polymer products, such as curable paints, foams, and adhesives.

==Health concerns==
[[Image:canned-air.jpg|thumb|[[Canned air]] / spray dusters are dangerous to inhale. They do not use compressed air, but rather other inert gasses.]]
There are two main areas of health concern linked to aerosol cans:
* Deliberate [[inhalant|inhalation]] of the contents to gain a high from the propellant
* The piggy-backing of more dangerous particles into the respiratory tracts

==Notes==
{{Reflist}}

== External links ==
* [http://www.patent-invent.com/aerosol_can_patent.html Aerosol Spray Can Old Patents and Inventions]

[[Category:Aerosols]]
[[Category:Containers]]
[[Category:Norwegian inventions]]

[[da:Spraydåse]]
[[de:Sprühdose]]
[[es:Pulverizador]]
[[eo:Sprajilo]]
[[fr:Spray aérosol]]
[[it:Bomboletta spray]]
[[nl:Spuitbus]]
[[ja:スプレー]]
[[no:Sprayboks]]
[[ru:Аэрозольный баллон]]
[[simple:Aerosol spray]]
[[sr:Аеросол-боца]]
[[fi:Suihkepullo]]
[[sv:Sprayburk]]
[[th:สเปรย์ละอองลอย]]

Aerosol spray dispenser

2009-12-30T23:15:44Z

Fluonova: /* Packaging */ add 2K aerosol principle

[[Image:Aerosol.png|thumb|right|250px|Aerosol spray can]]
'''Aerosol spray''' is a type of dispensing system which creates an [[Particulate|aerosol]] mist of liquid particles. This is used with a [[spray can|can]] or [[bottle]] that contains a liquid under pressure. When the container's valve is opened, the liquid is forced out of a small hole and emerges as an [[Particulate|aerosol]] or [[mist]]. As gas expands to drive out the payload, some propellant evaporates inside the can to maintain an even pressure. Outside the can, the droplets of propellant evaporate rapidly, leaving the payload suspended as very fine particles or droplets. Typical liquids dispensed in this way are [[insecticide]]s, [[deodorant]]s and [[aerosol paint|paint]]s. An [[atomization|atomizer]] is a similar device that is pressurised by a hand-operated pump rather than by stored gas.

== History ==
[[Image:Aerosol 1943.jpg|thumb|The aerosol spray canister invented by [[USDA]] researchers, Lyle Goodloe and William Sullivan.]]

The concepts of aerosol probably goes as far back as 1790.<ref name= Bellis> Bellis, Mary [http://inventors.about.com/od/astartinventions/a/aerosol.htm The History of Aerosol Spray Cans]</ref> The first aerosol spray can was invented in [[Oslo]] in November 23, 1927 by [[Erik Rotheim]], a [[Norway|Norwegian]] chemical engineer.<ref name= Bellis/> The patent was sold to a US company for 100,000 [[Norwegian krone|Norwegian kroner]].<ref>{{cite news|url=http://www.aftenposten.no/viten/article492297.ece|title=Sprayboksens far er norsk|last=Kvilesjø|first=Svend Ole|date=17 February 2003|work=Aftenposten|language=Norwegian|accessdate=6 February 2009}}</ref> The Norwegian Post Office celebrated the invention by issuing a stamp in 1998.<ref>[http://cache.aftenposten.no/multimedia/archive/00101/FRIMERKE_101049a.jpg Image of the Norway Postage stamp]</ref>

In 1939, American Julian S. Kahn received a patent for a disposable spray can<ref>Carlisle, Rodney (2004). ''Scientific American Inventions and Discoveries'', p.402. John Wiley & Songs, Inc., New Jersey. ISBN 0471244104.</ref>, but the product remained largely undeveloped. It was not until 1941 that the aerosol spray can was first put to good use by [[United States|Americans]] Lyle Goodhue and William Sullivan, who are credited as the inventors of the modern spray can.<ref name=McGrath>{{cite book |author=Kimberley A. McGrath (Editor), Bridget E. Travers (Editor) |title=World of Invention "Summary"| url= http://www.bookrags.com/research/aerosol-spray-woi/ |publisher=Thomson Gale |location=Detroit|year= |pages= |isbn=0-7876-2759-3 |oclc= |doi=}}</ref> Their design of a refillable spray can dubbed the “bug bomb”, was patented in 1943, and is the ancestor of many popular commercial spray products. Pressurized by liquefied gas, which gave it propellant qualities, the small, portable can enabled soldiers to defend against [[malaria]]-carrying [[Anopheles|mosquitoes]] by spraying inside [[tent]]s in the [[Pacific War|Pacific]] during [[World War II]].<ref>Core, Jim, Rosalie Marion Bliss, and Alfredo Flores. (September 2005) [http://ars.usda.gov/is/ar/archive/sep05/vector0905.htm?pf=1 "ARS Partners With Defense Department To Protect Troops From Insect Vectors"]. ''Agricultural Research Magazine''Vol. 53, No. 9 .</ref> In 1948, three companies were granted licenses by the United States government to manufacture aerosols. Two of the three companies still manufacture aerosols to this day, Chase Products Company and Claire Manufacturing. The "crimp-on valve", used to control the spray was developed in 1949 by [[Bronx]] machine shop proprietor [[Robert Abplanalp|Robert H. Abplanalp]].<ref name=McGrath/>

== Technology (aerosol propellants) ==

If aerosol cans were simply filled with compressed gas, it would either need to be at a dangerously high pressure or the amount of gas in the can would be small, and would rapidly deplete. Usually the gas is the [[vapor]] of a liquid with [[boiling point]] slightly lower than [[room temperature]]. This means that inside the pressurised can, the vapor can exist in [[thermodynamic equilibrium|equilibrium]] with its bulk liquid at a pressure that is higher than [[atmospheric pressure]] (and able to expel the payload), but not dangerously high. As gas escapes, it is immediately replaced by evaporating liquid. Since the propellant exists in liquid form in the can, it should be miscible with the payload or dissolved in the payload.

[[Chlorofluorocarbon]]s (CFCs) were once often used, but since the [[Montreal Protocol]] came into force in 1989, they have been replaced in nearly every country due to the negative effects CFCs have on Earth's [[ozone layer]]. The most common replacements are mixtures of volatile [[hydrocarbon]]s, typically [[propane]], n-[[butane]] and [[isobutane]]. [[Dimethyl ether]] (DME) and [[methyl ethyl ether]] are also used. All these have the disadvantage of being flammable. [[Nitrous oxide]] and [[carbon dioxide]] are also used as propellants to deliver foodstuffs (for example, [[whipped cream]] and [[cooking spray]]). Medicinal aerosols such as [[asthma inhaler]]s use [[hydrofluoroalkanes]] (HFA): either [[HFA 134a]] (1,1,1,2,-tetrafluoroethane) or HFA 227 (1,1,1,2,3,3,3-heptafluoropropane) or combinations of the two.

==Packaging==
[[Image:Aerosol tops 6.svg|thumb|223px|A typical paint valve system will have a "[[Gender of connectors and fasteners|female]]" valve, the stem being part of the top actuator. The valve can be preassembled with the valve cup and installed on the can as one piece, prior to pressure-filling. The actuator is added later.]]
Modern aerosol spray products have three major parts; the can, the valve and the actuator or button. The can is most commonly lacquered [[tinplate]] (steel with a layer of tin) and may be made of two or three pieces of metal crimped together. [[Aluminium]] cans are also common and are generally used for more expensive products. The valve is crimped to the rig of the can, the design of this component is important in determining the spray rate. The actuator is depressed by the user to open the valve; the shape and size of the nozzle in the actuator controls the spread of the aerosol spray.

Packaging that uses a piston barrier system is often used for highly viscous products such as post-foaming hair gels, thick creams and lotions, food spreads and industrial products and sealants. The main benefit of the piston barrier system is that is assures separation of the product from the propellant, maintaining the purity and integrity of the formulation throughout its consumer lifespan. The piston barrier system also provides a controlled and uniform product discharge rate with minimal product retention and is economical.

Another type of dispensing system is the bag-in-can system (or BOV “bag on valve”). This system separates the product from the pressurizing agent with a hermetically-sealed, multi-layered laminated pouch, which maintains complete formulation integrity so only pure product is dispensed. Among its many benefits, the bag-in-can system extends a product’s shelf life. The bag-on-valve, or ABS, is widely used by sun care marketers for its benefits: all-attitude (360-degree) dispensing, quiet and non-chilling discharge. This bag-in-can system is also used in the packaging of pharmaceutical, industrial, household, pet care and other products that require complete separation between the product and the propellant.

A new development is 2K (two component) aerosol paints or 2K adhesives. A 2K aerosol device has main component stored in main chamber of the aerosol can and a second component (usually a cross-linker) stored in an assesory container. When applicator activates the 2K aerosol by break the accessory container, the two components mix. The 2K aerosol can has the advantage for delivery reactive mixture instead a simgle component products. The applications are 2K curable paints and foams, and adhesives.

==Health concerns==
[[Image:canned-air.jpg|thumb|[[Canned air]] / spray dusters are dangerous to inhale. They do not use compressed air, but rather other inert gasses.]]
There are two main areas of health concern linked to aerosol cans:
* Deliberate [[inhalant|inhalation]] of the contents to gain a high from the propellant
* The piggy-backing of more dangerous particles into the respiratory tracts

==Notes==
{{Reflist}}

== External links ==
* [http://www.patent-invent.com/aerosol_can_patent.html Aerosol Spray Can Old Patents and Inventions]

[[Category:Aerosols]]
[[Category:Containers]]
[[Category:Norwegian inventions]]

[[da:Spraydåse]]
[[de:Sprühdose]]
[[es:Pulverizador]]
[[eo:Sprajilo]]
[[fr:Spray aérosol]]
[[it:Bomboletta spray]]
[[nl:Spuitbus]]
[[ja:スプレー]]
[[no:Sprayboks]]
[[ru:Аэрозольный баллон]]
[[simple:Aerosol spray]]
[[sr:Аеросол-боца]]
[[fi:Suihkepullo]]
[[sv:Sprayburk]]
[[th:สเปรย์ละอองลอย]]