PROCESS FOR PRODUCING RUBBER MIXTURE Russian patent published in 1994 - IPC

FIELD: tyre industry. SUBSTANCE: concept of new method of producing rubber mixture resided in mixing general-purpose unsaturated rubber with curing ingredients, target-oriented additives and crushed used vulcanized rubber tyre inner tubes. Rubber mixture included 100 parts by weight general-purpose unsaturated rubber, 2 to 3 parts by weight sulfur, 1.0 to 1.6 parts by weight curing promoter, 2.5 to 5.0 parts by weight zinc oxide, 1.0 to 2.5 parts by weight aliphatic acids, 0.5 to 3.0 parts by weight rosin, 2.0 to 4.0 parts by weight styrene-indene resin, 1.5 to 2.5 parts by weight protection wax, 10 to 18 parts by weight aromatic petroleum oil, 0.5 to 2.0 parts by weight N-isopropyl-N-phenyl-n-phenylenediamine, 1.0 to 2.5 parts by weight 2,2,4-trimethyl-1,2-dihydroquinoline polymer, 50 to 75 parts by weight commercial-grade carbon, and 4 to 20 parts by weight crushed used vulcanized tyre inner tube rubber. Waste rubber was consecutively processed in rotary crushing machine or by parallel disc cutters, reduced to pieces each measuring 200 to 300 mm maximum, comminuted by crushing box-grooved rolls having friction ratio 1 : 2 to 1 : 3.2 by repeatedly passing rubber through slit at temperature between 50 and 70 C to obtain particles from 2 to 10 mm in size and then finally ground at temperature of 70 to 80 C by smooth-surface rolls having slit of 0.1 to 0.2 mm in size, friction ratio 1 : 3 to 1 : 5 and shearing strain within limits of (3-5)·10³s^-1 , ratio of magnitude of gap to number of passes made through gap remaining within 0.02 to 0.1 mm. Thus comminuted mass was uniformly admitted into slit and allowed to pass throughout entire length of banked rolls in amount not exceeding 50 % of maximum throughput capacity of rolls at given clearance. Resultant rubber product exhibited higher physical and mechanical qualities. EFFECT: higher quality of end product. 1 tbl