Patent GB-1535947-A (GB)
Title: Flame retardant compositions
IPC: C08L25/18
Filed: 1976-04-30
Abstract: 1535947 Polyphenylene ether resin compositions GENERAL ELECTRIC CO 30 April 1976 17751/76 Headings C3R and C3K A flame retardant thermoplastic moulding composition comprises (a) a polyphenylene ether resin; (b) a vinyl aromatic resin; (c) a halogenated flame retardant; and (d) an organic iron compound, in which the organic group is derived from a compound of the formula where R 1  is selected from hydrogen, hydroxyl, and alkylene carboxy wherein the alkylene group has 1-4 carbon atoms; R 2  is selected from hydrogen, hydroxyl and C 1 -C 4 -alkyl; R 3  is selected from hydrogen, C 1 -C 4 -alkyl, OH, C 1 -C 4 -alkylene carboxy, aryl, aralkyl, alkaryl, alkylidene carboxy wherein the alkylidene group has 1-4 carbon atoms, n is 1-20, with the proviso that the compound has not more than 6 hydroxyl groups. Suitable iron compounds are ferric acetate, ferric citrate, ferrous gluconate and ferric stearate. The polyphenylene ether preferably has the formula where n is at least 50 and Q is selected from H, halogen, hydrocarbon radicals free of a tertiary alpha carbon atom, halohydrocarbon radicals having at last 2 C atoms between the halogen atom and the phenyl nucleus, hydrocarbonoxy radicals and halohydrocarbonoxy radicals having at least 2 carbon atoms. The vinyl aromatic resins preferably have at least 25% of their units of the formula wherein R<SP>1</SP> and R<SP>2</SP> are selected from C 1 -C 6  alkyl or alkenyl groups and hydrogen, R<SP>3</SP> and R<SP>4</SP> are selected from Cl, Br, H, C 1 -C 6 -alkyl, and R<SP>5</SP> and R<SP>6</SP> are selected from H, C 1 -C 6  alkyl or alkenyl groups or R<SP>5</SP> and R<SP>6</SP> may be linked together with the benzene ring to which they are attached to form a naphthyl group. The units may be copolymerized with monomers of the formula where R 8  and R 7  are selected from H, halogen, C 1 -C 4 -alkyl, carboalkoxy or R 7  and R 8  taken together represent an anhydride linkage, and R 9  is H, vinyl, C 1 -C 12  alkyl or alkenyl, cycloalkyl, carboalkoxy, alkoxyalkyl, alkylcarboxy, ketoxy, halogen, carboxy, cyano or pyridyl and n=0-9. Suitable resins (b) include polystyrene, monochloropolystyrene, rubber-modified, high impact polystyrene, copolymers of styrene and butadiene and/or acrylonitrile, styrene-maleic anhydride copolymer, polyalpha-methylstyrene, and various styrene containing block copolymers. Other resins are disclosed. Suitable flame retardants (c) have the formula wherein R is alkylene, alkylidene, or cycloaliphatic linkage, ether, CO, a sulphur-containing linkage, carbonate or phosphorus containing linkage, or 2 or more alkylene or alkylidene linkages connected by aromatic ether, ester, carbonyl, sulphide, sulphoxide, sulphone, or a phosphorus-containing linkage, or R may be derived from a dihydric phenol; Ar and Ar<SP>1</SP> are mono- or poly-cyclic aromatic groups; Y is an organic inorganic or organometallic radical provided that there is at least 1 halogen atom per aryl nucleus; X is alkyl, aryl, alkaryl, aralkyl or cycloaliphatic group which may be substituted, d is at least 1, e can be zero or a positive integer, a, b and c are 0 or a positive integer, and when b is not 0, neither a nor c are 0. Preferred flame retardants (c) are chlorinated- or brominated-benzene, -biphenyl or -terphenyl, a compound comprising 2 phenyl radicals separated by an alkylene group or -O- and having at least 2 Cl or Br atoms per phenyl group, monochloro-polystyrene, bromine or chlorine containing aromatic polycarbonates. The compositions may include reinforcing fillers, e.g. Al, Fe or Ni, carbon filaments, acicular calcium silicate, asbestos, TiO 2 , potassium titanate, titanate whiskers and glass flakes and fibres. The compositions may be prepared by blending the components in a mixer then compounding the mixture on a twin-screw extruder, chopping the extrudate into pellets and then injection moulding. In the examples compositions are prepared from (a) poly-(2,6- dimethyl-1,4-phenylene) ether (35 p.b.w.); (b) a polybutadiene rubber-modified high impact polystyrene (65 p.b.w.); and as component (c) any one of (1) hexabromobiphenyl, (ii) polychlorostyrene; (iii) decabromodiphenyl oxide and/or chlorinated terphenyl; (iv) a polycarbonate copolymer derived from tetrabromobisphenol A and bisphenol A; or (v) polychlorostyrene and hexachlorobiphenyl; and as component (d) any one of ferric citrate, ferric acetate, ferrous gluconate and ferric stearate.