SE341076

1,145,632. Irradiating unsaturated polyester films. CHEMISCHE INDUSTRIE SYNRES N.V. 10 July, 1967 [8 July, 1966], No. 31634/67. Heading B5B. [Also in Division C3] A self-supporting film is made by forming a film of a liquid unsaturated polyester, as defined below, dissolved in an unsaturated monomer, such that the ratio of unsaturated bonds in the monomer to that of the unsaturated bonds in the polyester is from 1À0: 1 to 1À7: 1, and exposing this film to a dose of high energy electrons in excess of 1 x 108 erg./g. sec., thereby to crosslink and solidify it, the polymerization continuing to an extent of at least 90%. By unsaturated polyester is meant a polycondensate of a dicarboxylic acid with a diol, said acid and/or diol containing, at least in part, α,#- or #,γ-unsaturated bonds. Exemplified are resins derived from phthalic acid anhydride/fumaric acid/propane-1,2-diol and isophthalic acid/ maleic anhydride/diethylene glycol, in each case dissolved in styrene monomer. Other monomers and polyester-forming acids and diols are specified. The solution is suitably cast on a roller having an electron reflective, e.g. stainless steel, surface, irradiated and wound up.