Editing Polyurethane (section)

==History==
[[File:1937 1952 Prof Otto Bayer Polyurethan.jpg|thumb|Otto Bayer in 1952 demonstrating his creation]]

[[Otto Bayer]] and his coworkers at [[IG Farben]] in Leverkusen, Germany, first made polyurethanes in 1937.<ref>{{cite journal |doi=10.1002/ange.19470590901 |title=Das Di-Isocyanat-Polyadditionsverfahren (Polyurethane) |journal=Angewandte Chemie |volume=59 |issue=9 |pages=257–72 |year=1947 |last1=Bayer |first1=Otto |bibcode=1947AngCh..59..257B }}</ref><ref>{{cite patent|country=DE|number=728981|fdate=1937-11-13|inventor=[[IG Farben|I.G. Farbenindustrie A.G.]]|title=Verfahren zur Herstellung von Polyurethanen bzw. Polyharnstoffen [Process for the production of polyurethanes or polyurea]|pubdate=1942-12-07}}</ref> The new polymers had some advantages over existing plastics that were made by polymerizing olefins or by [[polycondensation]], and were not covered by patents obtained by [[Wallace Carothers]] on [[polyester]]s.<ref name=Seymour>{{cite journal |doi=10.1021/ed069p909 |title=Polyurethanes: A class of modern versatile materials |journal=Journal of Chemical Education |volume=69 |issue=11 |page=909 |year=1992 |last1=Seymour |first1=Raymond B. |last2=Kauffman |first2=George B. |bibcode=1992JChEd..69..909S }}</ref> Early work focused on the production of fibers and flexible foams and PUs were applied on a limited scale as aircraft coating during [[World War II]].<ref name=Seymour/> [[Polyisocyanate]]s became commercially available in 1952, and production of flexible polyurethane foam began in 1954 by combining [[toluene diisocyanate]] (TDI) and polyester polyols.  These materials were also used to produce rigid foams, gum rubber, and [[elastomer]]s. Linear fibers were produced from [[hexamethylene diisocyanate]] (HDI) and [[1,4-Butanediol]] (BDO).

[[DuPont]] introduced polyethers, specifically [[poly(tetramethylene ether) glycol]], in 1956.  [[BASF]] and [[Dow Chemical]] introduced polyalkylene glycols in 1957. Polyether polyols were cheaper, easier to handle and more water-resistant than polyester polyols. [[Union Carbide]] and [[Mobay]], a U.S. [[Monsanto]]/[[Bayer]] joint venture, also began making polyurethane chemicals.<ref name=Seymour/> In 1960 more than 45,000 metric tons of flexible polyurethane foams were produced. The availability of [[chlorofluoroalkane]] blowing agents, inexpensive polyether polyols, and [[methylene diphenyl diisocyanate]] (MDI) allowed  polyurethane rigid foams to be used as high-performance insulation materials. In 1967, urethane-modified [[polyisocyanurate]] rigid foams were introduced, offering even better thermal stability and [[flammability]] resistance. 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 exhibited an all-plastic car in [[Düsseldorf]], Germany. Parts of this car, such as the [[Fascia (car)|fascia]] and body panels, were manufactured using a new process called [[reaction injection molding]] (RIM), in which the reactants were mixed and then injected into a mold. The addition of fillers, such as milled glass, [[mica]], and processed mineral fibers, gave rise to reinforced RIM (RRIM), which provided improvements in [[flexural modulus]] (stiffness), reduction in coefficient of [[thermal expansion]] and better thermal stability. This technology was used to make the first plastic-body automobile in the United States, the [[Pontiac Fiero]], in 1983. Further increases in stiffness were obtained by incorporating pre-placed glass mats into the RIM mold cavity, also known broadly as [[Injection molding|resin injection molding]], or structural RIM.

Starting in the early 1980s, water-blown microcellular flexible foams were used to mold gaskets for automotive panels and air-filter seals, replacing [[Polyvinyl chloride|PVC]] polymers.  Polyurethane foams are used in many automotive applications including seating, head and arm rests, and headliners.

Polyurethane foam (including foam rubber) is sometimes made using small amounts of [[blowing agent]]s to give less dense foam, better cushioning/energy absorption or thermal insulation. In the early 1990s, because of their impact on [[ozone depletion]], the [[Montreal Protocol]] restricted the use of many [[chlorine]]-containing blowing agents, such as [[trichlorofluoromethane]] (CFC-11). By the late 1990s, blowing agents such as [[carbon dioxide]], [[pentane]], [[1,1,1,2-tetrafluoroethane]] (HFC-134a) and [[1,1,1,3,3-pentafluoropropane]] (HFC-245fa) were widely used in North America and the EU, although chlorinated blowing agents remained in use in many developing countries. Later, HFC-134a was also banned due to high [[Ozone depletion potential|ODP]] and [[Global warming potential|GWP]] readings, and HFC-141B was introduced in early 2000s as an alternate blowing agent in developing nations.<ref>{{cite conference
  | first =Bert
  | last =Feske
  | title =The Use of Saytex RB-9130/9170 Low Viscosity Brominated Flame Retardant Polyols in HFC-245fa and High Water Formulations
  | book-title = Polyurethanes Expo 2004
  | pages = 309
  | publisher =Alliance for the Polyurethane Industry Technical Conference
  | date =October 2004
  | location =Las Vegas, NV
  | url = http://www.gbv.de/dms/tib-ub-hannover/48098803X.pdf
  | access-date =2007-08-01}}</ref>