Polychloroprene rubber belting

The hydrohalide is usually prepared by passing hydrogen chloride into a solution of masticated high-grade raw rubber in benzene at 10°C for about six hours. Excess acid is then neutralised and plasticisers and stabilisers are added. The benzene is removed by steam distillation and the product washed and dried. Alternatively the solution is cast on to a polychloroprene rubber belt, leaving a tough film after evaporation of the solvent. 

Polychloroprene rubber, such as is used for the Selby Conveyor belt, is a chlorinated derivative of isoprene. Fig. 20.5. 

Rubber compounds are mixed in house, by a two-stage mixing process. They are based, for the Selby belt, on polychloroprene rubber, a specially developed grade of Neoprene from Du Pont being preferred. Blends of natural and synthetic rubber (SBR) are commonly used for other qualities. 

Both bonding and cover compounds are based on polychloroprene rubber, for the Selby belt. The full formulation is not disclosed, but the principles are as follows. 

Depending on the grade of polymer, polychloroprene can be vulcanized by zinc oxide or magnesium oxide. Tetramethylthiuram disulfide can serve as a retarder. Polychloroprene is inferior to NBR for oil resistance but is still significantly better than natural rubber, SBR, or BR. Like NBR it also finds extensive use in such products as oil seals, gaskets, hose linings, and automotive engine transmission belts where resistance to oil absorption is important. Butyl rubbers are a copolymer of isobutylene and isoprene ... 

Chloroprene rubber, polychloroprene (CR). A syniheXic rubber produced by polymerization of chloroprene (2-chlorobutadiene, CH2=CCl—CH = CH 2). High weather and chemical resistance, better oil resistance than that of natural rubber products. Some applications building sheets, belts, cable insulations, technical rubber goods, contact adhesives. Trade names Baypren (FRG), Neoprene (USA). 

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