Patent GB-588574-A (GB)
Title: Improvements in rubber and synthetic rubber compositions
IPC: C08L21/00
Filed: 1944-12-19
Abstract: Natural and synthetic rubbers are plasticised by incorporating with a predominant amount of the rubber a lesser amount of a linear polyester of 1, 2-propylene glycol and sebacic acid, the polyester having a molecular weight of from 560 to 20,000 and preferably between 1700 and 8000 and being non-microcrystalline at above 30 DEG C.  The polyester may be made by the methods described in U.S.A. Specifications 2,071,250 and 2,249,950 using zinc chloride as catalyst.  About 10-40 per cent of the polyester may be compounded with the elastomer, either by mastication on rolls, or by mixing emulsions of the components and subsequently coagulating or drying in the form of a film; or in solution, the solvent of which is subsequently evaporated.  The elastomer may be pale crepe rubber, polymerized butadiene, isoprene, 2,3-dimethyl butadiene, piperylene or chlorobutadiene, or copolymers of these dienes with ethenoid monomers such as acrylonitrile, methacrylonitrile, acrylic and methacrylic acids and their methyl and ethyl esters, vinyl chloride, vinylidene chloride, vinyl acetate, styrene and vinyl naphthalene; and also the condensation products of sodium tetrasulphide with ethylene dichloride or b ,b 1-dichloro-diethyl ether.  The efficiency as plasticisers of these polyesters is compared with that of dibutyl phthalate in typical mixes containing a synthetic rubber, zinc oxide, b -phenyl naphthylamine, sulphur, carbon black, an accelerator and stearic acid.  Other substances such as tricresyl phosphate, dibutyl sebacate, zinc stearate, clay and asbestos may also be added.ALSO:Natural and synthetic rubbers are plasticized by incorporating with a predominant amount of the rubber a lesser amount of a linear polyester of 1,2-propylene glycol and sebacic acid, the polyester having a molecular weight of from 560 to 20,000 and preferably between 1,700 and 8,000 and being non-microcrystalline at above 30 DEG C.  The poly-ester may be made by the methods described in U.S.A. Specifications 2,071,250 and 2,249,950 using zinc chloride as a catalyst.  About 10-40 per cent. of the polyester may be compounded with the elastomer, either by mastication on rolls, or by mixing emulsions of the components and subsequently coagulating or drying in the form of a film; or in solution, the solvent of which is subsequently evaporated.  The elastomer may be pale crepe rubber, polymerized butadiene, isoprene, 2,3 dimethyl butadiene, piperylene or chlorobutadiene, or copolymers of these dienes with ethenoid monomers such as acrylonitrile, methacrylonitrile, acrylic and methacrylic acids and their methyl and ethyl esters, vinyl chloride, vinylidene chloride, vinyl acetate, styrene, and vinyl naphthalene; and also the condensation products of sodium tetrasulphide with ethylene dichloride or b b 1-dichloro diethyl ether.  The efficiency as plasticizers of these polyesters is compared with that of dibutyl phthalate in typical mixes containing a synthetic rubber, zinc oxide, b -phenyl naphthylamine, sulphur, carbon black, an accelerator and stearic acid.  Other substances such as tricresyl phosphate, dibutyl sebacate, zinc stearate, clay and asbestos may also be added.