Coated Films

摘要

1,176,204. Coated films. IMPERIAL CHEMICAL INDUSTRIES Ltd. 22 Dec., 1967 [27 Jan., 1967], No. 4206/67. Heading B2E. [Also in Division G2] Coated biaxially oriented organic thermoplastic polymeric film is produced by applying a layer of a copolymer of ethylene and another unsaturated monomer copolymerisable therewith to at least one surface of the film which is then stretched to biaxially orient it and subsequently applying the desired coating material to at least one of the coated surfaces. The copolymer may be applied as a melt, dispersion, or as a solution. The copolymer may be of ethylene and vinyl acetate, ethylene and an alkyl acrylate or methacrylate, or ethylene and other olefines e.g. propylene. The film may be of polymers or copolymers of alpha-olefines e.g. ethylene, propylene, butene, 4-methyl pentene 1; linear polyesters e.g. polyethylene terephthalate and polyethylene 1:2 diphenoxy ethane-4:41 dicarboxylate; polymers and copolymers of vinyl chloride; and polyhexamethylene and adipamide. The copolymer may be applied to an extruded polypropylene tube which is then expanded by internal gas pressure to stretch and orient it in the transverse direction and withdrawn at a greater rate than it is extruded to stretch and orient it in the longitudinal direction. The film may be sequentially stretched to orient it in two mutually perpendicular directions in its plane and the ethylene copolymer is applied to the film between the two stretching steps. The coating material may be a heat seal coating polymer, examples of which are given. The ethylene copolymer-coated film may be surface oxidized by treatment with chromic acid in sulphuric acid, hot nitric acid, ozone, corona discharge, ionising radiation or flame prior to further coating. A coating material may also contain ferro-magnetic materials, waxes and slip agents. The coated film may form pressure sensitive adhesive films, typewriter ribbons or carbon paper, photographic film, e.g. having a coating of a water permeable colloid such as gelatin containing photo-sensitive materials such as silver or diazo compounds, or if desired a photosensitive layer may be applied above the gelatin layer.