GB1049890A - Improvements in or relating to resins - Google Patents

Abstract

A copolymerizable mixture free from elements of atomic number greater than 9 (preferably 8) and from lithium comprises an unsaturated polyester, which is derived from a polycarboxylic acid and a polyhydric alcohol, an adduct of a diester of a dicarboxylic acid with a monoallylacetal of an at least trihydric alcohol, or an adduct of an ester of a dicarboxylic acid and a polyhydric alcohol with an unsaturated diacetal, and an ethylenically unsaturated monomer contains at least 0.3% by weight of boron as neutron moderator, either the acid component of the polyester being derived partly from boric acid or the monomer being at least partly an ester of boric acid or the polyester and/or the monomer containing boron hydride or chloride. The composition may also contain as additional neutron-absorbing substances boron, boron carbide, boron oxide, boron nitride or cadmium, europium, gadolinium or samarium or alloys thereof or compounds with elements of low atomic number, e.g. cadmium borate, carbonate or oxide. Other fillers such as carbon may be included, and the mass may be supported on cotton, polyamide, polyacrylonitrile, polyester, glass or fluorine-containing fabrics. The dicarboxylic acid may be maleic, fumaric, itaconic, citraconic or mesaconic acid, and saturated acids such as succinic acid, the phthalic acids, and endomethylene-tetra- or -hexahydrophthalic acids may be used in part. Polyhydric alcohols specified include ethylene and the propylene glycols, di- and tri-ethylene-glycols, 2:2-dimethylpropane-1:3-diol, 1:4-dimethylolcyclohexene, D - 2:3 - butene-1:4 - diol, hydrogenated p:p1 - dihydroxydiphenylpropane-2:2, or partially etherified or acetalized specified polyols, wherein the ether or acetal may be derived from allyl. Dimethylolbenzene and like compounds and addition products of alkylene oxides with resorcinol and like dihydrophenols may also be used. Polyols and monohydric alcohols may partly replace diols. Monohydroxymonocarboxylic acids such as ricinoleic and 12-hydroxystearic acids, optionally with higher polycarboxylic acids such as pyromellitic acid, and monocarboxylic acids such as benzoic acid and fatty acids with at least 12 C atoms may partly replace dicarboxylic acids. Dicarboxylic acids may be reacted with polyhydric alcohols and dicyclopentadiene in two stages. The polyester may be modified with resinic or long-chain fatty acids. Polyester unsaturation may be derived from dicarboxylic acid or diol or both. Numerous monomers specified include styrene, N-vinylpyrrolidone, vinyl acetate, allyl acetate, diallyl fumarate, triallyl cyanurate, acrylates and methacrylates, diallyl itaconate, and vinyl and allyl borate. Numerous peroxide catalysts and amine accelerators are specified. Mixtures of reactants may be used. In an example, a polyester from 1:2-propanediol, maleic and phthalic anhydrides, and boric acid is dissolved in styrene, mixed with benzoyl peroxide, paste, and heated to harden.