Butadiene for synthetic rubber

IG IG-Farbcnindustric in Germany developed many processes before World War n, but the one most associated with its name is probably the Aldol process for making butadiene for synthetic rubber. The name has been used also for the Bergius-Pier process. 

This process was used for the production of butadiene for synthetic rubber by both the former Soviet Union and Germany during World War II. 

This activity expanded greatly during World War II. Refiners, snch as Jersey Standard, Sun Oil, Shell, and Sacony-Vacuum, pioneered the mass production of advanced and strategically critical petrochemicals including butadiene for use as raw-material for synthetic rubber, toluene for m advanced explosives, as well as high-octane motor fuel and aviation gasoline. 

When polymerizing dienes for synthetic rubber production, coordination catalysts are used to direct the reaction to yield predominantly 1,4-addition polymers. Chapter 11 discusses addition polymerization. The following reviews some of the physical and chemical properties of butadiene and isoprene. 

Butadiene is by far the most important monomer for synthetic rubber production. It can be polymerized to polybutadiene or copolymerized with styrene to styrene-butadiene rubber (SBR). Butadiene is an important intermediate for the synthesis of many chemicals such as hexa-methylenediamine and adipic acid. Both are monomers for producing nylon. Chloroprene is another butadiene derivative for the synthesis of neoprene rubber. 

Butadiene is one of the group of big four petrochemical building blocks, in company with ethylene, propylene, and benzene. It is used primarily as a feedstock for synthetic rubber, elastomers, and fibers. Butadiene is a colorless gas at room temperature but is normally handled under pressure or refrigerated as a Liquid. 

Standard Oil Co. claims the use of polyisobutylene as a plasticizer for polyvinyl acetate. Copolymers of isobutylene with vinyl ethers and other monomers are mentioned in several patents. For synthetic rubbers, oligomers of butadiene are claimed. Rubberlike polyolefins (10 to 50% is sufficient) are used extensively for plasticizing phenolic resins to increase impact strength. 

Catalytic conversions were experimentally studied in Russia toward the end of the nineteenth century, and especially in the twentieth century, and regularities were empirically established in a number of cases. The work of A. M. Butlerov (1878) on polymerization of olefins with sulfuric acid and boron trifluoride, hydration of acetylene to acetaldehyde over mercury salts by M. G. Kucherov (1881) and a number of catalytic reactions described by V. N. Ipatieff beginning with the turn of the century (139b) are widely known examples. S. V. Lebedev studied hydrogenation of olefins and polymerization of diolefins during the period 1908-13. Soon after World War I he developed a process for the conversion of ethanol to butadiene which is commercially used in Russia. This process has been cited as the first example of commercial application of a double catalyst. Lebedev also developed a method for the polymerization of butadiene to synthetic rubber over sodium as a catalyst. Other Russian chemists (I. A. Kondakov I. Ostromyslenskif) were previously or simultaneously active in rubber synthesis. Lebedev s students are now continuing research on catalytic formation of dienes. 

Synthetic Rubber There are many different formulations for synthetic rubbers, but the simplest is a polymer of buta-1,3-diene. Specialized Ziegler-Natta catalysts can produce buta-1,3-diene polymers where 1,4-addition has occurred on each butadiene unit and the remaining double bonds are all cis. This polymer has properties similar to those of natural rubber, and it can be vulcanized in the same way. 

Patents on polymerisation catalysts 3 Japan, for synthetic rubber. I. Poly- (21) merisation catalysts for butadiene. (i) Titanitim polymerisation catalysts... 

Nitrix [Uniroyal]. TM for synthetic rubber latices of the butadiene-acrylonitrile type. 

Butadiene may insert into the M-R bond by 1,2-insertion or 1,4-insertion mode. The latter mode giving the poly-cA-1,4-butadiene is particularly important for producing materials for synthetic rubber tires. For isoprene polymerization the situation is further complicated because of the presence of the methyl substituent. Since the physical properties of poly-cw-l,4-isoprene are quite similar with those of natural rubber, knowing the means to control the polymerization behavior is of particular industrial importance. 

Butadiene-styrene copolymers and polyfbutadiene) for synthetic rubber applications ... 

Many applications are being found for synthetic rubbers, which are synthetic polymers possessing rubber-like properties. Among those available commercially are butadiene-styrene and butadiene-acrylonitrile (called Buna rubbers), polyisoprene, and polybutadiene. Their properties may be modified considerably more than vulcanized rubbers, particularly with respect to resistance to oxidizing agents, solvents, and oils. Their adhesion to metals, however, is generally poorer. 

Looking at the historical development of the emulsion pol)nnerization, it is seen that the trigger factor in this development was the necessity for synthetic rubber in the wartime. The production of styrene/butadiene rubber (SBR) satisfied this requirement. Today, millions of tons of S)mthetic latexes are produced by the emulsion pol3merization process for use in wide variety of applications. In the S)mthetic latexes, the most important groups are styrene/butadiene copolymers, vinyl acetate homopol)rmers and copol)nners, and polyacrylates. Other synthetic latexes contain copolymers of ethylene, styrene, vinyl esters, vinyl chloride, vinylidene chloride, acrylonitrile, cloroprene and polyurethane. 

Analysis of the white solid showed a high chlorine content, presumably derived from the catalyst, cuprous chloride, used to form the trimer. Preliminary analytical studies indicated the starting reactant was similar in structure to isoprene, the starting material for synthetic rubber. Because of the structural similarity, the starting material, now known to be 2-chloro-1,3-butadiene, was dubbed chloroprene. In fact, it was derived from the dimer and was found to be readily synthesized from the reaction of the dimer and hydrogen chloride. 

Acrylonitrile (H2C=CH-CN) is used as a co-polymer in approximately 25% of all synthetic fibers. It is further used for synthetic rubbers and for the production of acrylonitrile-butadiene-styrene plastics and styrene-acrylonitrile plastics. These ter- and co-polymers are used in the automobile industry and in the production of house wares, electrical appliances, suitcases, food packaging and disposable dishes. Acrylonitrile can also be a constituent in fabrics and paints (Bjorkner 1995). 

Figure 9.16 Dependence of C2 on Yj for synthetic rubber vuicanizates (57). Poiymers O, butadiene-styrene, (95/5) 3, butadiene-styrene, (90/10) ), butadiene-styrene, (85/15) , butadiene-styrene, (75/25) , butadiene-styrene, (70/30) X, butadiene-aciyionitriie,...

Emulsion polymerisation of a mixture of butadiene and styrene gives a synthetic rubber (Buna S GBS rubber), which is used either alone or blended with natural rubber for automobile tyres and a variety of other articles. 

The conjugated diene 1 3 butadiene is used m the manufacture of synthetic rubber and IS prepared on an industrial scale m vast quantities Production m the United States is currently 4 X 10 Ib/year One industrial process is similar to that used for the prepara tion of ethylene In the presence of a suitable catalyst butane undergoes thermal dehy drogenation to yield 1 3 butadiene... 

Elastomers. Elastomers are polymers or copolymers of hydrocarbons (see Elastomers, synthetic Rubber, natural). Natural mbber is essentially polyisoprene, whereas the most common synthetic mbber is a styrene—butadiene copolymer. Moreover, nearly all synthetic mbber is reinforced with carbon black, itself produced by partial oxidation of heavy hydrocarbons. Table 10 gives U.S. elastomer production for 1991. The two most important elastomers, styrene—butadiene mbber (qv) and polybutadiene mbber, are used primarily in automobile tires. 

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