The word rubber comes from the Indian cau-uchihu, which means "weeping tree". Natural rubber is formed by condensation and drying of latex from rubber tree with three leaves (see figure). 1770, British chemist J. priestley discovered that rubber can be used to erase pencil handwriting. At that time, the material used for this purpose was called rubber, which has been used ever since. The molecular chain of rubber can be crosslinked, and the crosslinked rubber has the ability of rapid recovery when deformed by external force, and has good physical and mechanical properties and chemical stability. Rubber is the basic raw material of rubber industry, which is widely used to manufacture rubber products such as tires, hoses, tapes and cables.
kind
Rubber is divided into natural rubber and synthetic rubber according to raw materials. According to the form, it is divided into block raw rubber, latex, liquid rubber and powder rubber. Latex is a colloidal water dispersion of rubber; Liquid rubber is an oligomer of rubber, which is usually a viscous liquid before vulcanization; Powder rubber is made by processing latex into powder, which is convenient for batching and processing. Thermoplastic rubber, which was developed in 1960s, was formed by the processing method of thermoplastic without chemical vulcanization. Rubber is divided into general type and special type according to its use.
Because rubber has good comprehensive properties and wide applications. Mainly includes: ① natural rubber. It is made from latex of Hevea brasiliensis, and its basic chemical composition is cis-polyisoprene. Good elasticity, high strength and comprehensive performance. ② Isoprene rubber. The full name is cis-1, 4- polyisoprene rubber, which is a high cis-synthetic rubber made of isoprene. Because its structure and performance are similar to natural rubber, it is also called synthetic natural rubber. ③ Styrene-butadiene rubber. Short for SBR, it is polymerized from butadiene and styrene. According to the production methods, it is divided into emulsion polymerized styrene-butadiene rubber and solution polymerized styrene-butadiene rubber. Its comprehensive performance and chemical stability are good. ④ Butadiene rubber. The full name is cis-1, 4- polybutadiene rubber, abBReviated as br, which is polymerized from butadiene. Compared with other general rubber, vulcanized cis-polybutadiene rubber has excellent cold resistance, wear resistance and elasticity, less heat generation under dynamic load and good aging resistance, and is easy to be used with natural rubber, chloroprene rubber and nitrile rubber.
Special rubber refers to rubber with some special properties. Mainly includes: ① chloroprene rubber. CR for short is polymerized from chloroprene. It has good comprehensive properties, such as oil resistance, flame retardancy, oxidation resistance and ozone resistance. However, it has high density, easy crystallization and hardening at room temperature, poor storage and poor cold resistance. ② Nitrile rubber. NBR for short is polymerized from butadiene and acrylonitrile. Good oil resistance and aging resistance, and can be used in air at 120℃ or oil at 150℃ for a long time. In addition, it also has water resistance, air tightness and excellent bonding performance. ③ Silicone rubber. The main chain consists of silicon atoms and oxygen atoms alternately, and the silicon atoms have organic groups. High and low temperature resistance, ozone resistance and good electrical insulation. (4) fluororubber. Synthetic rubber with fluorine atoms in its molecular structure. It is usually expressed by the number of fluorine atoms of fluorine-containing units in * * * polymers, such as fluororubber 23, which is a * * * polymer of vinylidene fluoride and chlorotrifluoroethylene. Fluorine rubber is resistant to high temperature, oil and chemical corrosion. (5) polysulfide rubber. It is formed by condensation polymerization of dihalides of alkali metals or alkaline earth metals and polysulfides. It has excellent oil resistance and solvent resistance, but its strength is not high, its aging resistance and processability are not good, and its smell is unpleasant. It is mainly used with nitrile rubber. In addition, there are polyurethane rubber, chlorohydrin rubber, acrylate rubber and so on.
The idea of synthetic rubber comes from the analysis and imitation of natural rubber. The birth and development of synthetic rubber industry depends on the source of raw materials, the maturity of monomer manufacturing technology and the choice of monomer, catalyst and polymerization method. In addition, rubber is the main material of vehicles (tires of automobiles and airplanes, etc.). ), its development is closely related to the demand for rubber in the war. Synthetic rubber was born during the First World War and was produced in small quantities to meet the urgent needs of the war. Synthetic rubber industry was established in the early 1930s. The second world war promoted the rapid development of multi-variety and multi-performance synthetic rubber industry. In the early 1950s, Ziegler-Natta catalyst was invented, and the monomer manufacturing technology was relatively mature, which made the synthetic rubber industry enter a new stage of synthesizing structured rubber. After 1960s, the output of synthetic rubber began to surpass that of natural rubber.
Analysis and imitation of natural rubber 1826, M Faraday first made a chemical analysis of natural rubber, and determined the experimental molecular formula of natural rubber as C5H8.
In 1860, C.G. Williams separated C5H8 from the pyrolysis product of natural rubber, named it isoprene, and pointed out that isoprene would be oxidized into white elastomer in air. In 1879, G. Bouchard prepared isoprene by thermal cracking, and made isoprene become an elastomer again. Although the structure and properties of this elastomer are quite different from those of natural rubber, it has been completely proved that it is possible to synthesize rubber with low molecular monomers.
The birth of synthetic rubber 1900 ил. Kondakov synthesized leather-like elastomer from 2,3- dimethyl-1, 3-butadiene. During World War I, German maritime transportation was blocked, cutting off the import of natural rubber. In 19 17, they used 2,3- dimethyl-1 3-butadiene to produce synthetic rubber for the first time, named methyl rubber w and methyl rubber h.
Methyl rubber W is made by thermal polymerization of 2,3- dimethyl-1, 3-butadiene at 70℃ for 5 months, while methyl rubber H is a hard rubber made by polymerization of the above monomers at 30 ~ 35℃ for 3 ~ 4 months. During the war, the output of methyl rubber * * * was 2350t, and the performance of this kind of rubber was much worse than that of natural rubber, and the synthesis and polymerization technology of monomer was backward at that time, so it was stopped after the war.
The establishment and development of synthetic rubber industry 1927 ~ 1928, American J.C. Patrick first synthesized polysulfide rubber (polyethylene tetrasulfide). W.H. carothers synthesized 2- chloro-1, 3- butadiene by J.A. Newland method, and prepared chloroprene rubber. 193 1 year, DuPont conducts small-scale production. In the Soviet Union, butadiene was synthesized from alcohol by с β Lebedev method, and sodium butadiene rubber was prepared by liquid phase bulk polymerization with metal sodium as catalyst. 193 1 build a 10,000-ton production plant. In the same period, Germany used acetylene to synthesize butadiene, and also used sodium as catalyst to prepare sodium butadiene rubber. In the early 1930s, German H staudinger (1932) established the theory of macromolecular long chain structure, and Soviet h·h· Semenoff (1934) established the theory of chain polymerization, which laid the foundation for polymer science. At the same time, the polymerization process and rubber quality have also been significantly improved. The representative rubber varieties in this period are: styrene-butadiene rubber polymerized from butadiene and styrene, and nitrile-butadiene rubber polymerized from butadiene and acrylonitrile. 1935, our company produced NBR for the first time. 1937, our company built an industrial production device of SBR in Buna Chemical Plant. Styrene-butadiene rubber is still the largest variety of synthetic rubber because of its excellent comprehensive properties, while nitrile rubber is oil-resistant rubber and still the main variety of special rubber. In the early 1940s, due to the urgent need of war, the development and production of butyl rubber technology were promoted. 1943, the United States began the trial production of butyl rubber. By 1944, the annual output of butyl rubber in the United States and Canada will be 1320t and 2480t respectively. Butyl rubber is a kind of synthetic rubber with good air tightness, which is most suitable for tire inner tube. Later, many new varieties of special rubber appeared. For example, American General Electric Company began to produce silicone rubber in 1944, and Germany and Britain produced polyurethane rubber in the early 1940s (see polyurethane). During the Second World War, Japan occupied Malaysia and other natural rubber producing areas, which further accelerated the research and production of synthetic rubber in North America and the Soviet Union, and made the world's synthetic rubber output sharply increase from 23. 12kt in 939 to 885.5kt in 1944. Due to the recovery of natural rubber supply after the war, the output of synthetic rubber fluctuated from 1945 to 1952 in the range of 432.9~893.9kt.
In the mid-1950s, new catalysts such as Ziegler-Natta and lithium series were invented. The petroleum industry provides a large number of advanced monomers for synthetic rubber; People have gradually realized the importance of the microstructure of rubber molecules to rubber properties. Coupled with the solution polymerization technology developed with new catalysts, it is possible to effectively control the stereoregularity of rubber molecules. These factors make the synthetic rubber industry enter a new stage of producing stereoregular rubber. The representative products are high cis-1, 4- polyisoprene rubber, which was put into production in the early 1960 s and referred to as synthetic natural rubber; High trans-1, 4- polyisoprene, also known as synthetic gutta percha; And high cis, medium cis and low cis-1, 4- polybutadiene rubber, called cis-butadiene rubber. In addition, there are ethylene-propylene rubbers prepared by solution polymerization of styrene-butadiene and ethylene-propylene During this period, special rubber has also made corresponding development, and rubber varieties with high temperature resistance, multi-media resistance, solvent resistance or both high temperature resistance and oil resistance have been synthesized. Its representative varieties are fluorine rubber and new acrylate rubber. In the 1960s, the synthetic rubber industry was characterized by the continuous development of new varieties, a substantial increase in output, and the emergence of various forms of rubber, such as liquid rubber, powder rubber and thermoplastic rubber, in order to simplify rubber processing technology and reduce energy consumption. By the late 1970s, synthetic rubber could basically replace natural rubber to make various tires and products, and some special synthetic rubber had properties that natural rubber did not have.
1950 The output of synthetic rubber reached about 600 kt. After 1950s, due to the rapid development of petrochemical industry, the corresponding synthetic rubber output increased by about 1000kt almost every five years (see table). 1979 broke through 9000kt, reaching a peak. The output of 1980 began to decline, and stabilized at about 8000kt in the following years, about twice the output of natural rubber, and the annual output of synthetic rubber reached about12 mt. By 2007, the global total output of rubber was 23.23 million tons, including 9.68 million tons of natural rubber and 3.32 million tons of synthetic rubber/kloc-0.
philology
G. synthetic rubber, John Wiley & new york, 1954.