GB1169708A - Process for Making Epoxy Cellular Plastics - Google Patents

Abstract

1,169,708. Foamed epoxy resins. FARBWERKE HOECHST A.G. 20 Sept., 1966 [23 Sept., 1965], No. 41995/66. Headings C3B and C3C. Epoxy cellular plastics are prepared by polymerizing at least one compound containing two or more epoxy groups per molecule in the presence of a surface-active agent and at least one aryldiazonium salt of a Lewis Acid which acts as polymerization catalyst and sole blowing agent. The epoxy compound may be a di- or polyglycidyl ether of a di- or poly-nuclear phenol, or of a di- or poly-hydric aliphatic, cycloaliphatic or araliphatic alcohol; preferred phenols are pyrocatechol, resorcinol, hydroquinone, bis - (4 - hydroxyphenyl)methane, bis- (4 - hydroxyphenyl) - ethane, bis - (4 - hydroxyphenyl) butane, bis - (4 - hydroxyphenyl - 2,3,5,6 - tetrachlorophenyl) - 2,2 - propane, 4,4<SP>1</SP> - dioxybenzophenone, bis - (4 - hydroxyphenyl) - cyclohexane, bis - (4 - hydroxphenyl) - phenylmethane, bis - (4 - hydroxy - 3- methyl - phenyl) - 2,2 - propane, bis - (4 - hydroxy - 3 - tert. butyl - phenyl) - 2,2 - propane, tris - (4 - hydroxyphenyl) - methane, a bis - (4- hydroxyphenyl) - pentane acid ester, and bis- (4 - hydroxyphenyl) - 2,2 - propane; preferred alcohols are ethylene glycol 1,4-butanediol, polyethylene glycols, cyclohexanediol-1,4, dimethylolcyclohexanes, glycerol, hexanetriols, and pentaerythritol. An epoxy compound having only one epoxy group per molecule may optionally be included; this may be a glycidyl ether of a phenol, e.g. of 2,4,6-tribromophenol which is fire-resistant. The aryl diazonium salt of a Lewis acid may be a substituted or unsubstituted aryl diazonium fluoborate, or may be the salt of tin tetrachloride, aluminium chloride, zinc chloride, zinc bromide, ferric chloride, or titanium tetrachloride, and is present in the reation mixture in 0À1 to 10% proportions by weight; the reaction mixture is heated between 30‹ and 150‹ C. to decompose the diazonium salt which releases nitrogen as the effective blowing agent. An amount not exceeding 3% by weight of a Lewis base may be added to control the amount of free Lewis acid acting as curing agent; suitable bases include ethers, thioethers, amines, acid amides, oximes and nitriles. 1 to 20 mole per cent of a compound that undergoes cationic polymerization may be incorporated; suitable are cyclic ethers, cyclic acetals, cyclic carboxylic anhydrides and copolymers of maleic anhydride, itaconic anhydride or citraconic anhydride with styrene, vinyl acetate, vinyl propionate, methyl acrylate, methyl methacrylate vinyl chloride, vinylidene chloride isobutylene ethylene or propylene. The surfactant present in up to 3% proportions by weight, may be a polysiloxane, an ethoxylated fatty alcohol amine, acid or rhenol, a fatty acid sulphate, an alkyl or aryl sulphonate, a paraffin oil or wax or a block copolymer of ethylene and propylene oxides.