GB1295162A - - Google Patents

Abstract

1295162 Paper-like films SUMITOMO CHEMICAL CO Ltd 13 March 1970 [15 March 1969] 12328/70 Addition to 1241876 Heading B5B [Also in Division C3] A synthetic paper-like material having an opaque white surface layer is made by treating a stretched styrene polymer film having a heat shrinkage percentage (defined by a formula in Specification) of 2 to 90% with a solvent system consisting of: (1) a solvent B or a mixture of such solvents or a mixed solvent being a mixture of solvents A and C, B and C, A and B, or A, B and C, the solvent B or the mixed solvent having a shrink-commencing time (time from dipping the film in the solvent, to the instant at which shrinkage begins) on the said film of 2 to 30 seconds, and (2) a solvent D which has substantially infinite shrink-commencing time (i.e. is a non-solvent for the polymer), and an evaporation velocity lower than that of B or the mixed solvent; solvent A having a shrinkcommencing time of 2 seconds or less, and solvent C having such a time of 30 seconds or more. Solvents A specified are chloroform and methyl acetate; solvents B are ethyl acetate, isobutyl acetate, acetone, methyl ethyl ketone, methyl isobutyl ketone, ethylene trichloride, CCl 4 , 1,1,2,2-ethane tetrachloride, benzene, toluene, xylene, 1,4-dioxane, dimethyl formamide and mixtures thereof; solvents C are cyclohexane, diisopropyl ether, dibenzyl ether, hexane and pentane and solvents D are alcohols of 1 to 10 carbon atoms such as isopropanol and n-propanol. The polymers are treated by immersion in the solvent system, or by coating them with it, and may contain fillers, stabilizers and other common ingredients. In the examples, films of high impact polystyrene, polystyrene and ABS resin, and high impact polystyrene containing 10% by wt. of rutile TiO 2 are treated.