Patent GB-782996-A (GB)
Title: Improvements in or relating to rubber compositions
Inventor: LEE GEOFFREY PHILIP
IPC: C08L25/10
Filed: 1954-12-24
Abstract: Compositions for reinforcing natural rubber comprise (1) a resinous butadiene-styrene copolymer containing at least 70 per cent of styrene and (2) a rubbery butadiene-methyl methacrylate copolymer containing at least 60 per cent of butadiene.  Aqueous dispersions of the copolymers may be blended, spraydried or coagulated, e.g. by aluminium sulphate solution, and the product milled with rubber, or the dispersions blended with rubber latex and the mixed latices coagulated.  Alternatively the copolymers may be milled in turn into rubber.  Pigments, fillers, e.g. calcium silicate, softeners, e.g. pale coumarone resin, paraffin wax, antioxidants, e.g. the condensate of mixed 2,4- and 2,5-dimethyl phenols with butyraldehyde, vulcanizing agents and accelerators, e.g. sulphur, zinc oxide, stearic acid, dibenzthiazyl disulphide and tetramethylthiuram disulphide, may be incorporated in the latices or compounded with the coagulates, and the compositions vulcanized by heating under pressure.  The copolymers may be prepared by aqueous emulsion polymerization in the presence of emulsifying agents, e.g. sodium lauryl sulphate, sodium oleyl sulphate, sodium cetyl sulphate, the sodium salt of sulphonated castor oil, the sodium salt of sulphonated or sulphated methyl oleate, sodium oleate, sodium palmitate and sodium stearate; modifiers, e.g. primary, secondary or tertiary aliphatic mercaptans having 6 to 18 carbon atoms such as lauryl, dodecyl or tertiary dodecyl mercaptan, dialkyl xanthogen disulphides, di-(benzoic acid ester) tetrasulphides, tolyldisulphide and tolyltrisulphide; and catalysts, e.g. hydrogen peroxide, potassium persulphate, or redox systems comprising cumene hydroperoxide or benzoyl peroxide, a heavy metal salt and optionally sorbose or fructose.  Other monomers, e.g. isoprene, dimethylbutadiene, vinyl acetate, a -methyl styrene, acrylonitrile, methyl acrylate, methacrylic acid, the nitriles, amides or alkyl esters of a -methyl unsaturated aliphatic carboxylic acids or vinyl carbazole may be included. When the polymerization is conducted below 0 DEG  C. methanol may be added to prevent freezing.  In the preparation of the rubbery copolymer the reaction is stopped at 80 to 85 per cent conversion, e.g. by the addition of hydroquinone.  The reinforced rubber may be used to form shoe soles.ALSO:Natural rubber is reinforced with composiNatural rubber is reinforced with compositions comprising (1) a resinous butadiene-styrene copolymer containing at least 70 per cent of styrene and (2) a rubbery butadiene-methyl methacrylate polymer containing at least 60 per cent of butadiene. The copolymers may be prepared from mixtures comprising additional monomers, e.g. isoprene, dimethyl-butadiene, vinyl acetate, a -methyl styrene, acrylonitrile, methyl acrylate, methacrylic acid, nitriles, amides and esters of a -methyl unsaturated carboxylic acids and vinyl carbazole.  Aqueous dispersions of the copolymers may be blended, spray dried or coagulated, e.g. with aluminium sulphate solution, and the product milled with rubber, or the dispersions blended with rubber latex and the mixed latices coagulated. Alternatively the copolymers may be milled in turn into rubber. Pigments, fillers, e.g. calcium silicate, softeners, e.g. pale coumarone resin, paraffin wax, antioxidants, e.g., the condensate of mixed 2, 4- and 2, 5-dimethyl phenols with butyraldehyde, vulcanising ingredients, e.g. sulphur, zinc oxide, stearic acid, dibenzthiazyl disulphide and tetramethylthiuram disulphide, may be incorporated in the latices or compounded with the coagulates, and the compositions vulcanised by heating under pressure.  The compositions may be used to form shoe soles.