| 摘要 |
PROBLEM TO BE SOLVED: To provide an unsaturated polyester having excellent thermal resistance, low thermal expansion, and processability together with low dielectric characteristics, namely low dielectric constant and low dielectric loss tangent, to provide a cross-linked polyester composition by further polymerizing the unsaturated polyester and to provide a method of producing it. SOLUTION: This unsaturated polyester consists of a polyester structural unit (I) and a fumarate structural unit (C), the former comprising a structural unit (A) expressed by phthaloyl group, isophthaloyl group, terephthaloyl group or naphtyl group or the like and a structural unit (B) expressed by divalent secondary and/or tertiary alkoxy group. This cross-linked polyester composition is produced by further polymerization of the polyester.
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