GB758397A - Improvements in or relating to natural or synthetic rubber composition and a method of compounding same - Google Patents

Abstract

In a method of compounding with additives a natural or synthetic rubber having a high viscosity and/or nerve, the viscosity and/or nerve of the rubber is/are reduced prior to the addition of most or all of the other additives by working it, at a temperature between room temperature and 240 DEG F., with a reaction product of tall oil and sulphur containing 1 to 25 per cent of sulphur based on the weight of tall oil, so that the reaction product is substantially completely dispersed in the rubber, whereafter the rubber is further worked with the or most of the other additives. The sulphurized tall oil may be added in liquid state at a temperature of 120 DEG to 180 DEG F., and may be prepared by heating tall oil with 8 to 10 per cent by weight of sulphur at 300 DEG to 400 DEG F., preferably 310 DEG to 330 DEG F., until no free sulphur remains. As examples are described the preparation of compounds containing sulphurized tall oil and natural rubber, butadiene acrylonitrile copolymer, chlorosulphonated polyethylene, and chloroprene, respectively. A compound including butadiene acrylonitrile copolymer and sulphurized tall oil is stated to be very compatible with other elastomers such as natural rubber, butadiene-styrene copolymers, and chloroprene.ALSO:In a method of compounding with additives a natural or synthetic rubber having a high viscosity and/or nerve, the viscosity and/or nerve of the rubber is/are reduced prior to the addition of most or all of the other additives by working it, at a temperature between room temperature and 240 DEG F., with a reaction product of tall oil, so that the reaction proper cent of sulphur based on the weight weight of tall oil, so that the reaction product is substantially completely dispersed in the rubber, whereafter the rubber is further worked with the or most of the other additives. The sulphurized tall oil may be added in liquid state at a temperature of 120 DEG to 180 DEG F., and may be prepared by heating tall oil with 8 to 10 per cent by weight of sulphur at 300 DEG to 400 DEG F., preferably 310 DEG to 330 DEG F., until no free sulphur remains. In one example 7 parts of sulphurized tall oil are mixed on a roll mill with 85 parts smoked sheets, after which are added and worked in sequence, 3 parts stearic acid, 50 parts carbon black, 16 parts of a master batch including zinc oxide, antioxidant, and smoked sheets, and 7.8 parts of a master batch comprising sulphur and smoked sheets. As other examples are described the preparation of compounds containing sulphurized tall oil and butadiene acrylonitrile copolymer, chlorosulphonated polyethylene, and chloroprene, respectively. A compound including butadiene acrylonitrile copolymer and sulphurized tall oil is stated to be very compatible with other elastomers such as natural rubber, butadiene-styrene copolymers, and chloroprene.