POLYESTERHARPIKSER.

摘要

A low viscosity unsaturated polyester resin for making products, optionally reinforced with glass fibers is described, which comprises an alkyd prepared by esterification of maleic anhydride and/or acid and/or fumaric acid in association with isophtalic acid, with one or more glycols, essentially comprising dipropylene glycol, and further comprises 25-40% by weight of the total resin of an ethylenically unsaturated monomer copolymerizable with the alkyd essentially chosen among styrene and vinyl toluene, the alkyd having a molecular weight/double bond factor between 300 and 390 and an amount of free functional groups between 50 and 85 mg of KOH per g of alkyd inclusive. The products obtainable from said resin are also described. The resin behaves better in processing has lower heat development and shrinkage than the comparable prior art resins while the mechanical properties of the finished products are very good.