| 摘要 |
A coated film comprises essentially a polyvinyl alcohol base sheet directly coated on at least one side with a polymer mixture of from 90 to 95% of a copolymer of from 50 to 75% vinylidene chloride and from 25 to 50% vinyl chloride, and from 5 to 10% of a terpolymer of from 75 to 94,5% vinyl chloride, from 5 to 24,5% vinyl acetate, and from 0,5 to 5% of an ethylenically unsaturated aliphatic carboxylic acid or anhydride thereof. The copolymer may contain substantially 60% by weight vinylidene chloride and substantially 40% by weight vinyl chloride. The unsaturated acid or anhydride is preferably a compound containing 3-6 carbon atoms, e.g. acrylic, methacrylic, crotonic, maleic and itaconic acid, and maleic anhydride. The terpolymer may contain substantially 86% vinyl chloride, 11% vinyl acetate and 3% maleic anhydride, or 86% vinyl chloride, 13% vinyl acetate and 1% maleic anhydride, the percentages being by weight. The film may have a thickness of between 0,0008 and 0,0012 inch and the polymer mixture may form a coating of a thickness of between 0,0001 and 0,00025 inch. The polymer mixture may be applied as a solution in an inert organic solvent, e.g. methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, and tetrahydrofuran. The film may be dried at a temperature between 40 and 110 DEG C. Conventional additives for improving slip can be incorporated in the coating composition. Static can be removed from the film by conventional means, e.g. passage of the film through a dilute aqueous or alcoholic solution of a surface active agent such as glycerol mono-oleate. Specifications 960,203 and 960,205 are referred to. |
