| 摘要 |
PROBLEM TO BE SOLVED: To provide a process for preparing a flexible and low-shrinkage thermoplastic polyurethane composition for molding which can be easily released from a mold and has good low-temperature properties and mechanical properties and a Shore A hardness of 45-65. SOLUTION: The process comprises (A) a step wherein a linear hydroxyl- terminated polyol is allowed to react with an organic diisocyanate, (B) a step wherein a prepolymer prepared in step (A) is mixed with an organic diisocyanate and (C) a step wherein a mixture obtained in step (B) is allowed to react with a diol chain extender. The molar ratio of NCO:OH in components used in step (A), (B) and (C) is adjusted to (0.9:1)-(1.1:1), and the ratio of OH groups in the polyol to OH groups in the chain extender is (0.3:1)-(2.0:1), preferably (0.4:1)-(1.5:1). COPYRIGHT: (C)2003,JPO
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