| 摘要 |
PURPOSE:To provide a shrinkage controlling agent which gives a cured resin having excellent surface smoothness, consisting of a lactone polymer obtd. by reacting a polyester resin, a lactone and a tri- or polyhydric alcohol. CONSTITUTION:n mol of a polyhydric alcohol (e.g. ethylene glycol) is reacted with (n+1) mol of a polybasic acid (e.g. maleic acid) to obtain a polyester resin contg. a carboxyl group at its terminal and having an MW of 300-20,000. 30-95wt% lactone (e.g. epsilon-caprolactone), 0.8-8wt% tri- or polyhydric alcohol (e.g. diglycerol) and 0.01-50ppm of a catalyst (e.g. tetrabutyl titanate) are added to said polyester resin. The mixture is reacted in an inert atmosphere at 130-240 deg.C to obtain a shrinkage controlling agent composed of a lactone polymer having an MW of 500-100,000. |
