GB877864A - Flame retardant or self-extinguishing polymer compositions and method for their production - Google Patents

Abstract

A flame-proof polymer composition comprises a halogen-containing flame-proofing agent, an organic peroxide in a proportion which enhances the effect of the halogen compound and, in the preferred embodiment of the invention, a volatile organic compound as foaming agent. The compositions may be obtained by dry blending, or by incorporation of the other ingredients into a melt, solution, gel, dispersion or emulsion of the polymer, or any or all of the composition components may be added during or before polymerization of the monomer, in which case the peroxide used as synergist must be a stable compound under the polymerization conditions. Particular compositions specified are those containing polymers and copolymers of alkenyl aromatic monomers, especially polymers of styrene, including cross-linked polymers, e.g. with divinyl benzene. Many organic peroxides are specified and those preferred are dicumyl and di-t-butyl peroxides, and di-t-butyl perphthalate, peracetate and perbenzoate. The exemplified halogen compounds include many bromine organic compounds, e.g. tetrabromoethane, dibromotetrachloroethane, tris (dibromopropyl) phosphate, pentabromomonochlorocyclohexane, ammonium bromide, and such materials as chlorinated paraffin and diiodomethane. The foaming agents disclosed are the pentanes, the butanes, hexane, heptane, petroleum ether, various perchlorofluorocarbons, methyl or ethyl chloride, dimethyl ether, methyl ethyl ether, butylene and propylene. Optional composition ingredients are inhibitors of corrosion when ammonium bromide is used, and specified are tris (nonylphenyl) phosphate, diethylamine salts of octylphenyl esters of phosphoric acid, salts of N-alkyl-b -aminobutyric acid and di (sec-butyl) phenyl monoethers of polyethylene glycols. Polymerization of monomer in the presence of composition components may be effected in mass or in aqueous dispersion in the presence of conventional ingredients such as benzoyl, acetyl, di-t-butyl or lauroyl peroxide, preformed polymers, potassium dichromate, polyvinyltoluene sulphonic acid sodium salt, sodium sulphate, sodium hydroxide and sodium lauryl sulphate. Foamed products may be prepared, (a) by forming a flowable gel of polymer and gaseous blowing agent, maintaining under pressure while the peroxide and flameproofing agent are incorporated and then extruding the gel into a low-pressure area, or (b) heat-blending the polymer with a saturated hydrocarbon or a chlorofluorocarbon and mixing the flowable gel with the flameproofing agent and organic peroxide, e.g. at 60 DEG -150 DEG C., extruding into a low-pressure and rapidly cooling; the composition may then be granulated and moulded to a foamed article, or (c) by polymerizing p the monomer in the presence of a volatile organic compound which is a non-solvent for the polymer obtained, the reaction preferably being effected in water or brine whereby latent-foaming beads may be obtained, or (d) by steeping or heating granules of polymer with the other composition ingredients while suspended in a non-solvent medium such as water, brine or aqueous solutions of alcohols, glycols or ketones. In a modification of the process for obtaining flame-proofed products, the shaped polymers, e.g. beads, pellicles, or expandable granules, are coated with a filmforming latex containing the peroxide and the flame-proofing agent. The products of the invention may be an admixture or a reaction product and may be formed into boards, rods, planks, floats, toys and ornaments.ALSO:Shaped polymers, particularly granules of polymers of alkenyl aromatic monomers-optionally expandable-are coated with a film-forming latex comprising a halogen-containing flame proofing agent and an organic peroxide in a proportion which enhances the effect of the halogen compound. Film-forming latices specified are those of butadiene/styrene copolymers, polybutadiene, vinylidine chloride/vinyl chloride copolymers, polyvinyl acetate, acrylate/methacrylate copolymers and butadiene/acrylonitrile copolymers. The flame proofing agent may be chlorinated paraffin, diiodomethane, ammonium bromide, tetrabromoethane, dibromotetrachloroethane, tris (dibromopropyl) phosphate, pentabromomonochlorocyclohexane or one of the many other specified bromo-organic compounds. Of the specified peroxides, dicumyl peroxide is preferred. In a modification the film-forming latex itself may be brominated to act as the flame-proofing agent and exemplified are the brominated latices of styrene/butadiene copolymers, styrene/butadiene/divinyl benzene copolymers, polyvinyl toluene and polystyrene. Thickening agents such as polyvinyl alcohol, polyacrylic acid and salts thereof, ammonium caseinate, carboxymethyl cellulose and salts thereof and methocel, are desirably included. A surface active agent also may be present. The coated beads obtained may be moulded to produce flame-proof products, optionally expanded. Preferred shaped polymers are those derived from styrene, ethyl vinyl benzene, vinyl toluene, vinyl xylene, isopropylstyrene, t-butylstyrene, chlorostyrene with or without acrylonitrile, methyl methacrylate or natural or synthetic rubber.ALSO:A flame-proof polymer composition comprises a halogen containing flame proofing agent, an organic peroxide in a proportion which enhances the effect of the halogen compound and in the preferred embodiment of the invention a volatile organic compound as foaming agent. The compositions may be obtained by dry blending, or by incorporation of the other ingredients into a melt, solution, gel, dispersion or emulsion of the polymer, or any or all of the composition components may be added during or before polymerization of the monomer, in which case the peroxide used as synergist must be a stable compound under the polymerization conditions. Particular compositions specified are those containing polymers and copolymers of alkenyl aromatic monomers, especially polymers of styrene, including cross-linked polymers, e.g. with divinyl benzene. Many organic peroxides are specified and those preferred are dicumyl and di-t-butyl peroxides, and di-t-butyl perphthalate, peracetate and perbenzoate. The exemplified halogen compounds include many bromine organic compounds, e.g. tetrabromoethane, dibromotetrachloroethane, tris (dibromopropyl) phosphate, pentabromomonochlorocyclohexane, ammonium bromide, and such materials as chlorinated paraffin and diiodomethane. The foaming agents disclosed are the pentanes, the butanes, hexane, heptane, petroleum ether, various perchlorofluorocarbons, methyl or ethyl chloride, dimethyl ether, methyl ethyl ether, butylene and propylene. Optional composition ingredients are inhibitors of corrosion when ammonium bromide is used and specified are tris (nonylphenyl) phosphate, diethylamine salts of octylphenyl esters of phosphoric acid, salts of N-alkyl-b -amino-butyric acid and di(sec -butyl) phenyl monoethers of polyethylene glycols. Polymerization of monomer in the presence of composition components may be effected in mass or in aqueous dispersion in the presence of conventional ingredients such as benzoyl, acetyl di-t-butyl or lauroyl peroxide, preformed polymers, potassium dichromate, polyvinyltoluene sulphonic acid sodium salt, sodium sulphate, sodium hydroxide and sodium lauryl sulphate. Foamed products may be prepared, (A) by forming a flowable gel of polymer + gaseous blowing agent, maintianing under pressure while the peroxide and flameproofing agent are incorporated and then extruding the gel into a low pressure area, or (B) heat-blending the polymer with a saturated hydrocarbon or a chlorofluorocarbon and mixing the flowable gel with the flameproofing agent and organic peroxide, e.g. at 60 DEG -150 DEG C., extruding into a low pressure and rapidly cooling; the composition may then be granulated and moulded to a foamed article, or (C) by polymerizing the monomer in the presence of a volatile organic compound which is a non-solvent for the polymer obtained, the reaction preferably being effected in water or brine whereby latent-foaming beads may be obtained, or (D) by steeping or heating granules of polymer with the other composition ingredients while suspended in a non-solvent medium such as water, brine, or aqueous solutions of alcohols, glycols or ketones. In a modification of the process for obtaining flame-proofed products the shaped polymers, e.g. beads, pellicles, or expandable granules, are coated with a film forming latex containing the peroxide and the flameproofing agent. The products of the invention may be an admixture or a reaction product and may be formed into boards, rods, planks, floats, toys and ornaments.