| 摘要 |
PROBLEM TO BE SOLVED: To obtain a seal material composition which can give a seal exhibiting assured sealability as well as the inherent low-temperature flexibility, which composition comprises a high-molecular-weight styrene block copolymer having a specified or higher number-average molecular weight, a microspherical filler, and a viscosity modifier and gives a seal material having a specified or smaller compression set in a specified temperature range. SOLUTION: This composition comprises 3-50 pts.wt. (A) high-molecular- weight styrene block copolymer having a number-average molecular weight of at least 100,000, 2-50 pts.wt. (B) microspherical filler, 5-80 pts.wt. (C) viscosity modifier such as a paraffinic oil, a tackifier such as a terpene resin, and a filler such as talc and gives a seal material having a compression set of at most 90 as measured according to JIS K6262 at 60-100 deg.C. Component A is a styrene/isoprene/styrene block copolymer or a styrene/ethylene/propylene/styrene block copolymer. Component B is a spherical hollow material having a shell structure having a mean particle diameter of at most 800μm and is exemplified by Shirasu balloons (a kind of pumiceous balloons), pearlite, fly ash balloons, or glass balloons.
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