Hitachi Chemical Company, Ltd.

Kouji Arakawa

Kanemasa Nomaguchi

Etsuji Iwami

Unsaturated polyester resin compositions that have a low shrinking property, and at the same time, an enough strength are provided. The compositions comprises (1) 30-70 parts by weight of an unsaturated polyester obtained by reacting terephthalic acid and/or isophthalic acid and one or more of unsaturated acids selected from the group consisting of maleic anhydride, maleic acid and fumaric acid, with a glycol, and having the unsaturation degree of 1.5-5.0 and the acid value of 18-40, (2) 70-30 parts by weight of .alpha.,.beta.-ethylenically unsaturated monomer, and (3) 5-30 parts by weight of a thermoplastic resin having the number average molecular weight of 5,000-500,000.

Low shrinkage unsaturated polyester resin compositions

Unsaturated polyester resin compositions that have a low shrinking property, and at the same time, an enough strength are provided. The compositions comprises (1) 30-70 parts by weight of an unsaturated polyester obtained by reactin terephthalic acid and/or isophthalic acid and one or more of unsaturated acids selected from the group consisting of maleic anhydride, maleic acid and fumaric acid, with a glycol, and having the unsaturation degree of 1.5-5.0 and the acid value of 18-40, (2) 70-30 parts by weight of .alpha.,.beta.-ethylenically unsaturated monomer, and (3) 5-30 parts by weight of an amorphous linear saturated polyester resin obtained by reacting terephthalic acid and/or isophthalic acid with a glycol component.

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Hitachi, Japan

Kouji Arakawa