| 摘要 |
871,305. Coated polyester films. DU PONT DE NEMOURS & CO., E.I. Oct. 22, 1959 [Nov. 19, 1958], No. 35890/59. Class 140. A dimensionally stable translucent drafting film comprises a flexible, biaxially-oriented, highly polymeric polyester film substantially composed of the polyesterification product of a dicarboxylic acid and a dihydric alcohol having on at least one surface, in order: (i) a thin layer of an adherent film-forming, essentially hydrophobic organic copolymer, and (ii) a thin layer of a water-soluble urea-, melamine-, or thiourea-formaldehyde resin, or their cationic-modified, aliphatic mono- and polyamine modified and guanidine modified forms containing uniformly dispersed, finely-divided discrete particles of a water-insoluble, translucence-producing, solid inorganic toothing agent having an average particle size from 0.1 to 10 microns. The copolymer may be a vinylidene chloride-acrylic ester-itaconic acid copolymer containing said ingredients in the respective amounts of 35 to 96%, 3.5 to 64.5% and 0.5 to 25%, by weight. The layer of watersoluble resin may be applied to both surfaces of the film and may contain barium sulphate, a liquid aliphatic glycol plasticizing agent, e.g. ethylene glycol, and a Werner complex of chromic chloride with a fatty acid of 12 to 25 carbon atoms. The polyester film may be of polyethylene terephthalate, and may have a thickness of from 75 to 250 microns and exhibit a shrinkage in both longitudinal and in a direction 90 degrees thereto of not more than 0.2% when heated under no significant tension to a temperature of 120‹ C. for a period of 5 minutes. The water-soluble resin is applied as an aqueous solution containing the toothing agent, to the hydrophobic copolymer coating on the polyester film, and the coated film is dried by heating it for 20 to 40 seconds at 70‹ to 95‹ C., and cured by heating it from 110‹ to 125‹ C. for 3 to 5 minutes. Specified toothing agents are silica, ground glass, titanium dioxide, chalk, talc, diatomaceous earth and magnesium carbonate. Specifications 578,079, 718,422, 766,290 and 786,176 are referred to. |
