| 摘要 |
PROBLEM TO BE SOLVED: To obtain a rubber composition which can give an extrudate reduced in poor shape stability and in a dispersion of physical properties in spite of being filled with hydrated silicic acid otherwise causing such disadvantages by incorporating a natural rubber and/or a synthetic rubber with a specified surface-treated hydrated silicic acid. SOLUTION: This composition comprises 100 pts.wt. natural rubber and/or synthetic rubber, 10-90 pts.wt., desirably, 15-80 pts.wt. surface-treated hydrated silicic acid which satisfies the relationships: 0.95>=BET(2)/BET(1)>=0.6, 1.1>= PO(2)/PO(1)<=0.9, 300 >=PO(2)>=100, and 300>=BET(2)>=125 [wherein BET(1) is the nitrogen adsorption specific surface area (m2/g) before surface treatment; BET(2) is the nitrogen adsorption specific surface area after surface treatment; PO(1) is the mercury porousimetry specific surface area (m2/g) before surface treatment; and PO(2) is the mercury porosimetry specific surface area (m2/g) after surface treatment], and, optionally, 1-20 wt.%, based on the hydrated silicic acid, silane coupling agent, and at most 80 pts.wt., desirably, 5-70 pts.wt. carbon black.
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