| 摘要 |
PROBLEM TO BE SOLVED: To obtain a viscoelastic material which can give a vehicle seat which is mild to the hip, stabilizes the body, and can have a reduced thickness by adding a plasticizer to a thermoplastic elastomer having a specified or larger molecular weight distribution in terms of a ratio of the weight-average molecular weight to the number-average molecular weight. SOLUTION: At least 250 pts.wt. plasticizer is added to 100 pts.wt. thermoplastic elastomer having an Mw/Mn ratio of 2 or greater. The obtained material can give a vehicle seat which reacts soft to sitting and reacts hard to a load, such as shock or vibration, which produces a large deformation. The material is used as part of the cushion of a vehicle seat being an assemblage of a bottom seat and a cushion covered with a sheety skin and is buried in the body of the cushion. The thermoplastic elastomer used is a styrene-type one containing a polystyrene and a hydrogenated polyisoprene, and the plasticizer used is a paraffinic process oil. A preblend is irradiated with EB orγ-rays and molded with e.g. an extruder.
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