Rubber composition, useful for tire manufacture, contains carbon black and styrene/butadiene copolymer rubber and natural rubber

摘要

A new rubber composition (COM) contains starting rubber comprising: (a) SBR-carbon black (CB) rubber composition, styrene/butadiene copolymer rubber, (SBR); (b) natural rubber (NR)-CB-rubber composition, plant rubber; and (c) butadiene rubber and/or styrene/butadiene copolymer rubber. A new rubber composition (COM) contains: (i) 100 parts weight of a starting rubber comprising: (a) SBR-carbon black (CB) rubber composition (40-120 parts), with a weight ratio of CB of nitrogen specific surface area (N2SA) of at least 70 m2/g to at least one styrene/butadiene copolymer rubber, (SBR), of 0.4-1; (b) natural rubber (NR)-CB-rubber composition (40-120 parts), with a weight ratio of CB of N2SA of at least 70 m2/g to plant rubber (NR) of 0.4-1; and (c) butadiene rubber and/or styrene/butadiene copolymer rubber (0.4-1), with a Tg value at least 10 deg C higher than that of the SBR of the starting rubber in the SBR-CB rubber composition (a); and (ii) 80 parts or less of total plasticizer. The rubber composition is obtained by mixing in an internal mixer. The composition has a ratio FMB/FCOM of 1.2 to 3.0 (where FMB = the mean CB concentration, based on the total amount of rubber in the CB-containing rubber compositions (a) and (b); and FCOM = the CB concentration based on the amount of rubber in the rubber composition COM) An Independent claim is also included for a rubber composition including: (i) a CB-containing plant rubber master charge, obtainable by mixing a plant rubber (NR)-starting latex and CB in a water based medium, followed by coagulation and drying; (ii) an additional starting rubber of glass transition temperature (Tg) of -50-20 deg C; and (iii) silicon dioxide. The components are mixed in an internal mixer.