| 摘要 |
PURPOSE:To obtain a sealing material resistant to the migration of a softener, having suppressed compression set and improved sealability and effective in preventing the cracking under high compressive force at a high temperature, by modifying a composition composed of a polyisobutylene, etc., with an unsaturated silane compound. CONSTITUTION:The objective sealing material suitable for a heat-accumulation tank or hot-water tank, etc., is produced by modifying (A) a composition containing (i) 75-90wt.% of a hydrogenated derivative of a styrene-butadiene block copolymer having a number-average molecular weight of 100,000-200,00, (ii) 15-25wt.% of a polyisobutylene, (iii) 25-10wt.% of a hydrocarbon oil and (iv) 10-20wt.% of a propylene homopolymer and/or a propylene-ethylene or 4-8C alpha-olefin copolymer resin having a flexural modulus of >=6,000kg/cm<2> with (B) an unsaturated silane compound of formula (R is hydrocarbon-oxy, etc., R' is aliphatic saturated hydrocarbon group; Y is hydrolyzable organic group; n is 0-2) and, as necessary, contacting the modified resin with water in the presence of a silanol condensation catalyst to effect the crosslinking of the resin to a gel ratio of 30-50%. |
