| 摘要 |
<p>977,052. Pneumatic tyres. GOODYEAR TIRE & RUBBER CO. July 23, 1963 [Aug. 30, 1962], No. 29068/63. Heading B7C. A pneumatic tyre tread has a cap-base construction as shown, utilizing two different types of rubber. The cap portion 11 comprises a blend of 20-75% of polybutadiene, having at least 30% of its monomer units in a cis 1, 4 configuration and less than 15% of its monomer units polymerized through 1, 2 addition, and 80-25% of a copolymer of butadiene and styrene. The base portion 12 comprises 20- 75% of a polybutadiene as defined above and 80-25% of polyisoprene in which at least 80% is of cis-1,4 structure. The polyisoprene may be natural rubber or synthetic polyisoprene. The base portion 12 may contact the tyre carcase 10 directly, as shown, or breaker strips may separate them. In manufacture the composite tread is made by separate extrusion of cap and base portions which are then fed through a common extruder.</p> |
