Low shrink unsaturated polyester resinous composition

Claim 1

A molding compound containing fibrous reinforcement comprising: (a) a low shrink polyester which is a product of a mixture of (i) from about 25 to about 35 parts by weight of a member selected from the group consisting of maleic acid, fumaric acid, their anhydrides and mixtures thereof; from about 5 to about 25 parts by weight of a member selected from the group consisting of isophthalic acid, phthalic acid, their anhydrides, and mixtures thereof; from about 10 to about 40 parts by weight propylene glycol; from about 10 to about 30 parts by weight dipropylene glycol; from about 5 to about 30 parts by weight propylene glycol terephthalate; (ii) heating said mixture of about 420° F. until a neat resin is formed with an acid number of from about 5 to about 50; and (iii) diluting the neat resin with from about 25 to about 100 parts by weight of a member selected from the group consisting of styrene, vinyl toluene and mixtures thereof; (b) mixing said resin with a filler, fibrous reinforcing agent and catalyst-initiator.