摘要 |
PROBLEM TO BE SOLVED: To make both high impregnation operating efficiency and thioxotropy compatible with each other by using an unsaturated polyester resin, a polymerizable monomer and a thioxotropy imparting agent as main components and making the blending contents of the unsaturated polyester resin and the polymerizable monomer satisfy a specific formula and further setting the viscosity and the thioxotropy of the resin and the monomer within a specific range. SOLUTION: When the blend content of an unsaturated polyester resin (a) is given as (a) pts.wt. and the blend content of a polymerizable monomer (b) is given as (b) pts.wt., both unsaturated polyester resin (a) and polymerizable monomer (b) are blended in such a content ratio as to meet the formula (1). Besides, the viscosity of the blend falls within the range of 0.5-8.0 Pa.s and the thioxotropy within the range of 1.2-4.4. In case a/(a+b) exceeds 0.70, the viscosity of a heat-curable resin composition tends to be excessively high, so that the composition shows the deterioration of the impregnation operating efficiency. On the other hand, in case the a/(a+b) is 0.50 or below, the thioxotropy imparting effects are hardly obtainable sufficiently and at the same time, the mechanical strength tends to be significantly undermined. Thus it is possible to achieve the high impregnation operating efficiency and the good thioxotropy which prevents the heat-curable resin composition from sagging.
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