Mixtures of unsaturated polyesters and monomeric ethylene compounds copolymerizable therewith containing cobalt salts and a member of the group of arsines, stibenes, andphosphines

Mixtures of unsaturated polyesters which contain the residues of a , b -unsaturated dicarboxylic acids, and of monomeric ethylenically unsaturated compounds copolymerizable therewith which are hardenable at 20-25 DEG C. with ketone peroxides in the presence of cobalt accelerators to give resins which are not coloured green contain one or more phosphines, arsines and/or stilbines, e.g. 0.01-1%, which may be added at 20-70 DEG C. The polyester may be derived from maleic, fumaric, itaconic, mesaconic or citraconic acids or anhydrides and an ethylene glycol glycol diol e.g. butan-1, 3-diol, propan-1, 2-diol, glycerol, trimethylol propane or pentaerythritol and may containa saturated polycarboxylic acid or anhydride, e.g. phthalic, adipic The copolymerizable monomer may be styrene, vinyltoluene or trimethylol propane diallyl ether. Examples of the phosphines, arsines and stibines are given. The cobalt accelerator may be the naphthenate or octoate and the peroxide may be cyclohexanone or methylethyl ketone peroxides. The mixture may contain a polymerization inhibitor e.g. a quinone or substituted pyrocatechol. Specification 827,511 is referred to.