| 摘要 |
1,274,078. Expandable vinyl aromatic polymers. KAUCUK NARODNI PODNIK. 18 Sept., 1969 [20 Sept., 1968], No. 46036/69. Headings C3C and C3P. An expandable vinyl aromatic polymer is made by polymerizing a vinyl aromatic monomer in aqueous suspension in the presence of a wax and a foaming agent and at a temperature above the melting point of the wax which has a melting point of from 70‹ to 120‹ C., a saponification number of from 3 to 150, and an acid number of from 0 to 45, and which is present in the amount of from 0À02 to 0À3% by weight, of the monomer. The wax may be admixed with the aqueous suspension at the end of a partial conversion of the monomer to the polymer, and the polymerization may be continued in the presence of the wax at a temperature not exceeding 130‹ C. and for from 0À5 to 25 hours until at least 99% conversion of the monomer to the polymer is attained. In the examples styrene was polymerized in an aq. mixture of dibenzoyl peroxide, polyvinylalcohol, tert. butylperbenzoate, an aliphatic hydrocarbon and a wax, with polystyrene; and/or zinc, calcium or aluminium stearate. |
