| 摘要 |
1,139,496. Writing surfaces. E. I. DU PONT DE NEMOURS & CO. 3 Jan., 1967 [3 Jan., 1966], No. 228/67. Heading B6A. [Also in Divisions B2 and G2] A drafting film comprises (1) a flexible, dimensionally stable, biaxially oriented polyester film having dispersed therein 0.5 to 10% by weight, based on the polyester, of non- porous crystalline silica having an average particle size of 1 to 5 microns and a surface area of 0À5 to 2.2 sq. m./gm., the said film carrying at least one of the layers (2) and (3); where layer (2) is a composition made by polymerizing, in the presence of gelatine, at least one of the vinyl monomers of vinylidene chloride, methyl acrylate and ethyl acrylate, the weight ratio of gelatine to total monomer in said layer being between 1 : 1 and 9 : 1 and layer (3) is formed by one or more water-permeable organic colloid layers. The polyester may be from a glycol of formula HO(CH 2 ) n OH where is 2-100 or 1,4-cyclohexamedimethanol and terephthalic acid or its diethyl or dimethyl ester, with or without a second dibasic acid, e.g. isophthalic, bibenzoic, sebacic, hexahydroterephthalic, adipic, azelaic. naphthalic or 2,5-dimethyl terephthalic acid on bis-p-carboxy phenoxy ethane. Layer (2) may contain a surfactant, e.g. sodium N-coco-#-amino propionate or cetyl betaine and a silica hydrosol. The polyester surface may be treated by electrical discharge, flame treatment or treatment with chromic acid, sulphuric acid, sodium hydroxide, oxygen or azone in the presence of U.V. |
