THERMOPLASTIC POLYESTER LOW PROFILE ADDITIVES FOR VINYL ESTER POLYESTER RESINOUS COMPOSITIONS

The present invention is based on the unexpected discovery that the low profile additives (LPA) disclosed in U.S. Pat No. 5,116,917 provide effective shrinkage control when used with various blends of vinyl ester and polyester resin systems. This LPA is unique in that its low profile efficiency is not affected by the differen t reactivities displayed by blends of vinyl ester resin and polyester resin at different blend ratios. This LPA is equally effective is formulations of all vinyl ester resin, all polyester resin, or any combination of such two resins. The present invention, then, is directed to a thermosettable resinous composition of between about 0 and 95 wt-% of a thermosettable vinyl ester resin; between about 5 a nd 100 wt-% of a thermosettable polyester resin; and between about 5 and 40 wt-% of a low profile additive comprising a non- gelling, saturated polyester formed from dibasic acid and an EO/PO block copolymer having an EO/PO molar ratio ranging from about 0.1 to 0.9, said polyester having an acid value of greater than about 10. The EO/PO polyether polyol can be built on a combination of diol, triol or other compound with active hydrogen groups, so long as the LPA product does not gel.