Research and Development History of Cyanohydric Acid

The research and development of polyurethane was initially started by OttoBayer and his colleagues at the I.G.Farben laboratory in Leverkusen, Germany, at 1937. They used the principle of addition polymerization to produce a new type of plastic, polyurethane, from liquid isocyanate and liquid polyether or diol polyester, which was different from polyolefin and polycondensation plastic found at that time. The new monomer mixture is also different from the polyester patent obtained by WallaceCarothers. At first, the application was limited to fiber and soft foam. Subsequently, its development was influenced by World War II (during which PU was only used in aviation seats on a small scale), and isocyanate was not commercialized until 1952. From 65438 to 0954, toluene diisocyanate (TDI) and polyester polyol were used to produce flexible polyurethane foam for commercial drawing. The invention of this kind of foam (originally called Swiss-like cheese by the inventor) is attributed to the addition of water to the reaction system, which is also used to produce rigid foam, viscose and elastomer. Linear fiber is prepared by the reaction of hexamethylene diisocyanate (HDI) and 1, 4- butanediol (BDO).

The first commercially produced polyether polyol, poly (tetramethylene ether) diol, was polymerized by DuPont and tetrahydrofuran in 1956. BASF and Dow Chemical introduced cheaper polyalkyl glycol in 1957. These polyether polyols show technical and commercial advantages, such as: low cost, easy handling, excellent hydrolysis stability; But also can quickly replace polyester polyol when preparing polyurethane. Other polyurethane promoters include UnionCarbide and MobayCorporation, a joint venture between Monsanto and Bayer. 1960 The output of flexible polyurethane foam reached 45,000 tons. After more than ten years of development, with the emergence of chlorofluoroalkane foaming agent, cheap polyether polyol and diphenylmethane diisocyanate (MDI), the application of rigid polyurethane foam in high-performance thermal insulation materials has been promoted. Rigid polyurethane foam based on polymeric MDI(PMDI) has better thermal stability and combustion performance than materials based on TDI.

Polyurethane modified polyisocyanate rigid foam was produced during the period of 1967, and the produced low-density thermal insulation material showed good thermal stability and flame retardancy. Also in the 1960s, the internal safety components of automobiles, such as instrument panels and door panels, began to be made of thermoplastics filled with semi-rigid foam.

1969, bayelage exhibited an all-plastic car in dü sseldorf, Germany. Some parts of cars are made by a new process called RIM (Reaction Injection Molding). RIM technology is to inject liquid components with high pressure, and then quickly inject the reaction components into the mold cavity. Large parts, such as automobile dashboard and panel, can also be injection molded in the same way. Polyurethane RIM includes many different products and processes. The trimerization process of binary ammonia chain extender and carbamate, isocyanate and polyurea was adopted, and additives such as ground glass, mica and processed fiber were added. , is the so-called RRIM. Bending modulus and thermal stability can be improved. 1983, the United States used this technology to produce automobile plastic bodies. Adding glass fiber in the cavity in advance can further improve the bending modulus, which is called SRIM or structural RIM.

Since the early 1980s, water-foamed microcellular flexible polyurethane foam has been used as a typical gasket for automobile panels and tire sealing air filters. Since then, the market share of polyurethane has been increasing due to the rising energy price and the increasing demand for reducing the use of PVC in automobiles. Expensive raw material prices are compensated by weight reduction of components, such as metal cover and filter housing. Highly filled polyurethane elastomer and unfilled polyurethane foam are now used in high temperature oil filters.

When producing polyurethane foam (including foamed rubber), a small amount of volatile substances should be added to the reaction mixture, which is called foaming agent. These simple substances give polyurethane excellent thermal insulation performance. In the early 1990s, in order to reduce the impact on the ozone layer, the Montreal Protocol restricted the use of some chlorine-containing foaming agents. Such as trichlorofluoromethane (CFC- 1 1). Other halogenated hydrocarbons, such as chlorofluorocarbons, 1, 1- dichloro-1- fluoroethane (HCFC- 14 1b), are subject to IPPC greenhouse gas directive 1994 and EU organic volatile gas directive/kloc. By the end of 1990s, carbon dioxide, pentane, 1, 1, 1, 2- tetrafluoroethane (HFC- 134a), 1 and 1 were used more and more in North America and Europe, although some of them were developing.

Based on the existing polyurethane spraying technology and polyether ammonia chemistry theory, polyurethane spraying elastic materials developed rapidly in the 1990s. Their quick response and relative insensitivity to moisture make them the first choice for large-scale projects. Such as secondary seals, manhole and channel coatings, and tank linings. After proper primer and surface treatment, it has good adhesion to concrete and steel. At the same time, a new two-component polyurethane and polyurethane polyurea hybrid elastomer technology was applied to the loading bed liner in field construction. This coating technology for trucks and other transport containers creates a durable and friction-resistant composite metal material. Thermoplastic lining makes up for the defects of metal in corrosion and brittleness.