GB1014981A - Fire retardant compositions comprising methyl methacrylate polymers - Google Patents

Abstract

Fire retardant compositions comprise a homopolymer or copolymer of methyl methacrylate, said copolymer containing a major proportion by weight of polymerized methyl methacrylate, and from 3 to 25% by weight based on the weight of said homopolymer or copolymer of mono-(2-chloroethyl) phosphate and/or bis (2-chloroethyl) phosphate. Suitable co-monomers for the copolymer include acrylic acid, methacrylic acid, esters, particularly C1- 12 alkyl esters, of acrylic and methacrylic acid, styrene, substituted styrenes, e.g. halostyrenes, maleimide, N-substituted maleimides, e.g. N-aryl maleimides, acrylonitrile and mixtures thereof. The polymers used can be prepared by known bulk or solution polymerization methods. Other ingredients may optionally be included in the compositions, e.g. dyestuffs, U.V. absorbers, heat stabilizers, plasticizers, substances which render the composition opalescent, e.g. polystyrene, and known fire-retardant agents. In an example, fire-retardant polymethyl methacrylate sheets are prepared by adding a mixture of mono-(2-chloroethyl) phosphate and bis-(2-chloroethyl) phosphate together with azo-diisobutyronitrile to a partially polymerized methyl methacrylate syrup, and moulding the mixture at elevated temperature; comparison processes are also illustrated using mixtures of the corresponding ethyl, n-propyl, n-butyl and isopropyl acid phosphates instead of the chloroethyl acid phosphates.