History of polyurethane

A pioneering study of polyurethane polymers was carried out in 1937 by Otto Bayer and his colleagues at the IG Farben Institute in Leverkusen, Germany. They have a special opportunity to produce polyurethanes from liquid diisocyanates and liquid polyethers or polyester diols using the polyaddition principle, especially when compared to existing plastics produced by olefin polymerization or polycondensation. I realized that it looks like it’s showing. The new monomer combination also circumvented Wallace Carothers’ existing patent on polyester. Initially, the work focused on the production of textiles and flexible foams. Development was constrained by World War II (when PU was applied on a limited scale as an aircraft coating), and polyisocyanates were only available on the market until 1952. Commercial production of flexible polyurethane foams based on toluene diisocyanate (TDI) and polyester polyols began in 1954. The invention of these forms (originally called imitation Swiss cheese by the inventor) was due to the water mistakenly introduced into the reaction mixture.

These materials were also used in the production of rigid foams, gum rubbers, and elastomers. The linear fibers are made from hexamethylene diisocyanate (HDI) and 1,4-butanediol (BDO). The first commercially available polyether polyol, poly (tetramethylene ether) glycol), was introduced in 1956 by polymerizing tetrahydrofuran with DuPont. The cheaper polyalkylene glycol was introduced by BASF and Dow Chemical in 1957 the following year. These polyether polyols offered technical and commercial advantages such as low cost, ease of handling and improved hydrolysis stability. It was quickly replaced by polyester polyols in the manufacture of polyurethane products. Another early pioneer of PU was Mobay. In 1960, over 45,000 tonnes of flexible polyurethane foam were manufactured. Over the course of 10 years, the availability of chlorofluoroalkane foaming agents, inexpensive polyether polyols, and methylene diphenyl diisocyanate (MDI) has foretold the development and use of polyurethane rigid foams as high performance insulation. .. Rigid foam based on polymer MDI (PMDI) provided better heat. Stability and combustion characteristics than those based on TDI. In 1967, urethane-modified polyisocyanurate rigid foam was introduced to provide even better thermal stability and flame retardancy for low density insulation products.

Also, in the 1960s, automotive interior safety components such as instruments and door panels were manufactured by backfilling semi-rigid foam in thermoplastic skins. In 1969, Bayer AG exhibited an all-plastic car in Düsseldorf, Germany. The parts of this car were manufactured using a new process called RIM, reactive injection molding. RIM technology uses a high pressure collision of liquid components followed by a rapid flow of reaction mixture into the mold cavity. Large parts such as automobile fascia and body panels can be molded this way. Polyurethane RIM has evolved into a variety of products and processes. Using diamine chain extenders and trimerization techniques, poly (urethane urea), poly (urethane isocyanurate), and polyurea RIM were obtained. The addition of fillers such as crushed glass, mica, and processed mineral fibers generated RRIM and reinforced RIM, improving flexural modulus (rigidity) and thermal stability. This technology enabled the production of Pontiac Fiero, the first plastic body car in the United States, in 1983. The flexural modulus was further improved by incorporating a pre-positioned glass mat into the RIM mold cavity, also known as SRIM or structural RIM. Since the early 1980s, water-blown microcellular flexible foam has been used in the automotive industry to mold gaskets for panels and radial seal air filters. Since then, market share has increased significantly due to rising energy prices and the desire to eliminate PVC plastisols from automotive applications. Expensive raw materials are offset by a significant reduction in component 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 currently used in high temperature oil filter applications. Polyurethane foam (including foam rubber) is often produced by adding a small amount of volatile material, the so-called foaming agent, to the reaction mixture. These simple volatile chemicals provide important performance properties, primarily thermal insulation. In the early 1990s, due to its impact on ozone depletion, the Montreal Protocol significantly reduced the use of many chlorine-containing foaming agents, such as trichlorofluoromethane (CFC-11). Other haloalkanes, such as hydrochlorofluorocarbons 1,1-dichloro-1-fluoroethane (HCFC-141b), are phased out under the 1994 IPPC Directive on Greenhouse Gases and the Volatile Organic Compounds (VOC) Directive. It was used as a temporary replacement until it was done. 1997 EU (see: Haloalkane). By the late 1990s, foaming agents such as carbon dioxide, pentane, 1,1,1,2-tetrafluoroethane (HFC-134a), 1,1,1,3,3-pentafluoropropane (HFC-245fa) Increased use of. Chlorinated foaming agents have continued to be used in many developing countries, but are widespread in North America and the EU.

Large-scale development of two-component polyurea spray elastomers was carried out in the 1990s based on existing polyurethane spray coating technology and polyetheramine chemistry. Their fast reactivity and relative insensitivity to moisture make them useful coatings for secondary containment, manhole and tunnel coatings, tank liners and other large surface area projects. With proper primer and surface treatment, excellent adhesion to concrete and steel can be obtained. At the same time, new two-component polyurethane and hybrid polyurethane-polyurea elastomer technologies were used to enter the market for spray-in-place roadbed liners. This technique, which coats pickup truck beds and other cargo bays, creates a durable and wear-resistant composite with metal substrates, eliminating the corrosion and brittleness associated with drop-in thermoplastic bed liners. Manufacture of polyurethane products using vegetable oil-derived polyols began to attract attention around 2004. This is due to rising costs of petrochemical raw materials and growing public demand for environmentally friendly green products. One of the loudest supporters of these polyurethanes made using natural oil polyols is Ford Motor Company.