GB586397A - Improvements in the co-polymerisation of substances containing allyl compounds - Google Patents

Abstract

A mixture of an unsaturated polyester and a compound containing an allyl or substituted allyl group is polymerized in the presence of metallic copper and either tertiary butyl hydroperoxide or tertiary amyl hydroperoxide. An unsaturated polyester is defined as the product formed by reacting a dihydric alcohol with a dibasic acid either or both of which are unsaturated. Specified alcohols are ethylene, diethylene and triethylene glycol and specified acids are maleic, fumaric and itaconic acids. Preferred allyl compounds are allyl esters of dibasic or tribasic acids, e.g. diallyl phthalate. The process may be applied to the electric insulation of copper wire coils or other copper conductors by first coating them, either bare or enveloped in such materials as cotton, silk or paper, with a mixture of an unsaturated polyester, the allyl compound and the hydroperoxide and then heating to copolymerize. In order to avoid oxidation, this copolymerization can be carried out either by immersing the copper in the mixture or by using a vacuum and heating in an inert atmosphere, e.g. nitrogen. In examples: (1) a polyester is prepared by heating diethylene glycol and maleic anhydride, the product mixed with diallyl phthalate and tertiary butyl hydroperoxide in tertiary butyl alcohol, copper wire immersed in the mixture and the whole heated; (2) and (3) a copper wire is immersed in a mixture of diethylene maleate, diallyl phthalate and tertiary amyl hydroperoxide in tertiary amyl alcohol and heated; (4) as in (2) and (3) using as catalyst tertiary butyl hydroperoxide in tertiary butyl alcohol.