| 摘要 |
A granular expandable polystyrene composition contains as a fire-retardant a minor amount of a compound of formula Ar(Br)m(Cl)nR or Ar(Br)x(Cl)yOR where Ar is an aryl residue, m is 1-4, n is 0-2, x is 1 or more, y is 0 or an integer and R is hydrogen, a straight or branched chain alkyl group which may be halogenated, a straight or branched chain alkenyl group or a halogenated aryl group; there being at least 2 nuclear bromine atoms per molecule of the above compound. The compound may be tetrabromobenzene, tribromophenol, pentabromophenyl (allyl, ethyl or n-propyl) ether, an isomer of tribromotoluene or tribromophenyl allyl ether, chlorodibromotoluene, chlorodibromophenyl allyl ether, hexabromodiphenyl ether, dibromodiphenyl, dibromonaphthalene; 2,4 - dibromo - 1 - methylnaphthalene; 1,5 - dibromoanthracene; pentabromophenyl dibromopropyl ether, pentabromophenol or tetrabromochlorophenol. The composition may also contain dicumyl or di-tert. butyl peroxide, tert. butyl peracetate or cumene hydroperoxide. The compositions may be made by polymerizing styrene in the presence of the fire-retardant compound, polystyrene granules, benzoyl peroxide, water and petroleum ether as expanding agent and the resulting polymer may be granulated, expanded by heating in steam and then moulded into a block. |
