| 摘要 |
1510050 Foaming temporary plasticized polyvinyl chloride LONZA Ltd 30 Dec 1976 [9 Jan 1976] 54299/76 Heading C3C A hard foamed polyvinyl chloride is made by heating a mixture of polyvinyl chloride, a blowing agent and a temporary plasticizer which is a polymerizable monomer having at least one ethylenically unsaturated double bond under pressure in a pressure mould cooling the mixture, removing the formed body from the mould, expanding the body by heating and then polymerizing the monomer, after completion of the expansion, by means of ionizing radiation which is U.V. rays, X-rays, gamma-rays, #-particles or accelerated electron beams. The monomer may be a C1-8 alkyl or a glycol ester of acrylic, methacrylic or maleic acid. In the example a mixture of polyvinyl chloride, calcium carbonate dibasic lead phthalate, ammonium bicarbonate and methyl methacrylate was heated under pressure in a mould, cooled and expanded in a drying cabinet and the foamed body was then treated with electrons to polymerize the methacrylate. |
