GB708809A - Improvements in the production of modified polyester resins - Google Patents

Abstract

Modified polyester resins are prepared by esterifying polyesters having at least one free hydroxyl group at the end of the polyester chain with an amount of an unsaturated aliphatic dicarboxylic acid sufficient for at least the partial esterification of the hydroxyl group or groups, and reacting with a vinyl compound, e.g. styrene, vinyl chloride, ethers and esters, acrylic esters and acrylonitrile, in an amount not more than is equivalent to the double linkages present. The polyesters are prepared from a saturated dicarboxylic acid (n-mols) or a functional derivative thereof, e.g. oxalic, malonic, succinic, glutaric, pimelic, adipic, sebacic, phthalic and terephthalic acids, and a saturated dihydric alcohol (at least n-1 mols) such as glycol, propanediol -1, 3, butanediol -1, 3, and -1, 4, di- and triglycols (HOCH2 . CH2 . O . CH2 . CH2OH and <FORM:0708809/IV (a)/1> , and hexanediol -1, 6, by usual methods with or without catalysts and with continuous removal of the water formed. In the second stage, unsaturated dicarboxylic acid, e.g. maleic and fumaric is added and the esterification carried out with the acid of heat or usual catalysts. The vinyl compounds are added together with polymerisation catalysts, e.g. benzoyl peroxide, or with oxygen of the air. Resins such as colophony may be added to the ester before the addition of the vinyl compounds. Examples describe the preparation of phthalic anhydride -diethylene glycol and triethylene glycol esters and a sebacic acid -diethylene glycol ester; their reaction with maleic acid; and their polymerisation with styrene, vinyl acetate, linoleic acid vinyl ester and vinyl octyl ether, under pressure with or without benzoyl peroxide. In a modification in which the phthalic anhydridediethylene glycol ester is reacted with maleic acid, colophony is added before polymerisation with styrene.