Polyurethanes History

 The pioneering take steps concerning polyurethane polymers was conducted by Otto Bayer and his coworkers in 1937 at the laboratories of I.G. Farben in Leverkusen, Germany. They ascribed that using the polyaddition principle to manufacture polyurethanes from liquid diisocyanates and liquid polyether or polyester diols seemed to narrowing to special opportunities, especially behind compared to already existing plastics that were made by polymerizing olefins, or by polycondensation. The added monomer inclusion moreover circumvented existing patents obtained by Wallace Carothers on polyesters.Initially, feint focused on the production of fibres and gymnastic foams. With worsen constrained by World War II (following PU's were applied upon a limited scale as plane coating), it was not until 1952 that polyisocyanates became commercially easily reached. Commercial production of athletic polyurethane foam began in 1954, based upon toluene diisocyanate (TDI) and polyester polyols. The invention of these foams (initially called imitation swiss cheese by the inventors) was thanks to water accidentally introduced in the response incorporation.

These materials were as well as used to fabricate rigid foams, cement rubber, and elastomers. Linear fibres were produced from hexamethylene diisocyanate (HDI) and 1,4-butanediol (BDO). The first commercially easy to do to polyether polyol, poly(tetramethylene ether) glycol), was introduced by DuPont in 1956 by polymerizing tetrahydrofuran. Less costly polyalkylene glycols were introduced by BASF and Dow Chemical the following year, 1957. These polyether polyols offered profound and trailer advantages such as low cost, ease of handling, and greater than before hydrolytic stability; and speedily supplanted polyester polyols in the manufacture of polyurethane goods. Another before voyager in PU's was the Mobay corporation. In 1960 on summit of 45,000 tons of in society polyurethane foams were produced. As the decade progressed, the availability of chlorofluoroalkane blowing agents, within your means polyether polyols, and methylene diphenyl diisocyanate (MDI) heralded the evolve and use of polyurethane rigid foams as high do its stuff insulation materials.Rigid foams based upon polymeric MDI (PMDI) offered bigger thermal stability and combustion characteristics than those based upon TDI. In 1967, urethane modified polyisocyanurate rigid foams were introduced, offering even improved thermal stability and flammability resistance to low density insulation products.

Also during the 1960s, automotive interior safety components such as instrument and entre panels were produced by urge on the subject of-filling thermoplastic skins furthermore than semi-rigid foam. In 1969, Bayer AG exhibited an each and every one one of plastic car in Dusseldorf, Germany. Parts of this car were manufactured using a supplement process called RIM, Reaction Injection Molding. RIM technology uses high-pressure impingement of liquid components followed by the sudden flow of the confession merged into a mold cavity. Large parts, such as automotive fascia and body panels, can be molded in this appearance. Polyurethane RIM evolved into a number of other products and processes. Using diamine chain extenders and trimerization technology gave poly(urethane urea), poly(urethane isocyanurate), and polyurea RIM. The count 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 Sates, the Pontiac Fiero, in 1983. Further improvements in flexural modulus were obtained by incorporating preplaced glass mats into the RIM mold cavity, pen pronounce SRIM, or structural RIM. Starting in the into the future 1980s, water-blown microcellular athletic foam was used to mold gaskets for panel and radial seal ventilate filters in the automotive industry. Since then, increasing life prices and the agonized to eliminate PVC plastisol from automotive applications have greatly increased look share. Costlier raw materials are offset by a significant confront in part weight and in some cases, the taking away of metal detain caps and filter housings. Do you know about polyurea coating?

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 appendage little amounts of volatile materials, in view of that-called blowing agents, to the greeting mixture. These easy volatile chemicals go along as soon as important con characteristics, primarily thermal insulation. In the to come 1990s, because of their impact upon ozone depletion, the Montreal Protocol led to the greatly edited 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 the theater replacements until their phase out sedated the IPPC directive upon greenhouse gases in 1994 and by the Volatile Organic Compounds (VOC) directive of the EU in 1997 (See: Haloalkanes). 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.