Unsaturated polyester molding compounds with improved resistance to thermal and humid aging

摘要

The compositions disclosed herein comprise a mixture of: P P(1) An unsaturated polyester resin; such as the polymeric ester of maleic acid or anhydride and a glycol such as ethylene glycol; and PP(2) The reaction product of a polyepoxy compound, such as the diglycidyl ether of bisphenol-A, and an unsaturated monocarboxylic acid, such as acrylic or methacrylic acid, in which reaction product there remains unreacted at the time of mixing with said polyester resin at least 5 percent of the original epoxy groups of said polyepoxy compound.PPThis mixture when molded or cured gives improvement with respect to thermal and humid aging as compared to similar compositions in which the epoxy groups of said reaction product are substantially all reacted prior to mixture with said unsaturated polyester resin. The flexural strength, in particular, of the compositions are better retained on aging without adverse effect on other properties.