Patent GB-916213-A (GB)
Title: Improvements in or relating to self-extinguishing foams
IPC: C08F8/20
Filed: 1959-12-07
Abstract: Self-extinguishing expandable polymeric material is prepared by suspending particles of a vinyl aryl polymer or copolymer in an aqueous medium in the presence of at least 2% by weight of bromine, based on the weight of the particles, activating the bromine until the colour of the medium changes from orange to pale yellow, and recovering the polymeric material from the medium after reaction of the particles with the activated bromine, the particles being made expandable before, during or after treatment with the bromine by incorporating therein a volatile aliphatic hydrocarbon, boiling point -10 DEG -81 DEG C.  In a modification, the aqueous medium contains less bromine and there is incorporated into the particles 0,5-4% of a phosphorus compound of empirical formula R1R2R3On wherein Rz is a C4-10 aliphatic hydrocarbon radical, R2 and R3 are C4-10 alkyl radicals, phenyl, phenyl lower alkyl or lower alkyl phenyl radicals or hydrogen atoms and n is 3 or 4. Polymers and copolymers specified are polystyrene, a copolymer of styrene and a -methyl styrene, and copolymers of a vinyl aryl monomer such as styrene and such monomers as butadiene, isobutylene and acrylonitrile.  The bromine may be activated with ultra violet light or a free radical type of initiator may be present of which there are specified potassium persulphate, sodium persulphate, sodium perborate, peracetic acid, 2-azo-bis (isobutylonitrile) and numerous peroxides and hydroperoxides.  The aqueous medium for the bromination contains a dispersing agent, e.g. sodium dodecyl benzene sulphonate, zinc oxide, calcium carbonate, bentonite, talc, kaolin, calcium phosphate, aluminium oxide, barium sulphate and magnesium carbonate.  In the modification, the phosphoric compound may be 2-ethylhexyldiphenyl phosphate, triisooctyl phosphite, bis-(2-ethylhexyl) hydrogen phosphate or triisobutyl phosphate.  Specifications 690,124 and 777,384 are referred to.ALSO:Self-extinguishing expandable polymeric material is prepared by suspending particles of a vinyl aryl polymer or copolymer in an aqueous medium in the presence of at least 20% by weight of bromine, based on the weight of the particles, activating the bromine until the colour of the medium changes from orange to pale yellow, and recovering the polymeric material from the medium after reaction of the particles with the activated bromine, the particles being made expandable before, during or after treatment with the bromine by incorporating therein a volatile aliphatic hydrocarbon, b.pt.-10-81 DEG C.  In a modification, the aqueous medium contains less bromine and there is incorporated into the particles 0,5-4% of a phosphorus compound of empirical formula R1 R2 R3 POn wherein R1 is a C4-10 aliphatic hydrocarbon radical, R2 and R3 are C4-10 alkyl radicals, phenyl, phenyl lower alkyl or lower alkyl phenyl radicals or hydrogen atoms and n is 3 or 4. Polymers and copolymers specified are polystyrene, a copolymer of styrene and a -methylstyrene, and copolymers of a vinyl aryl monomer such as styrene and such monomers as butadiene, isobutylene and acrylonitrile.  The bromine may be activated with u.v. light or a free radical type of initiator may be present of which there are specified potassium persulphate sodium perborate, peracetic acid, sodium persulphate 2 azo-bis-(isobutylo-nitrile) and numerous peroxides and hydroperoxides.  The aqueous medium for the bromination contains a dispersing agent, e.g. sodium dodecyl benzene sulphonate, zinc oxide, calcium carbonate, bentonite, talc, kaolin, calcium phosphate, aluminium oxide, barium sulphate and magnesium carbonate.  For the modification, the phosphorus compound may be 2-ethylhexyldiphenyl-phosphate, triisooctyl phosphite, bis-(2-ethylhexyl) hydrogen phosphate or triisobutyl phosphate. Specified expanding agents are isopentane, isohexane, n-pentane, neopentane, butane, 2, 4-dimethylpentane and petroleum ether. Specifications 690,124 and 777,384 are referred to.