Patent GB-1264338-A (GB)
IPC: C08J7/046
Filed: 1969-07-15
Abstract: 1,264,338. Coated polyester film. IMPERIAL CHEMICAL INDUSTRIES Ltd. 29 June, 1970 [15 July, 1969], No. 35556/69. Heading B2E. [Also in Division G2] Coated biaxially oriented synthetic linear polyester films are produced by melt extruding a substantially amorphous polyester film, drawing the film in the longitudinal direction, thereafter applying a primer coating other than a heat sealable coating to one or both sides of the film and then drawing the coated film in the transverse direction, whereby a primer coating thickness of at least 10<SP>-7</SP> inches is obtained. Primer coating materials mentioned include vinylidene chloride copolymers containing more than 95% vinylidene chloride, the reaction product of polyisocyanate and a polyhydric alcohol with a phenol, polyacrylic acid, polyurethanes, e.g. as formed from polyisocyanate mixtures with polyesters or polyethers, the condensation product of a monoaldehyde with an inter-polymer of acrylamide or methacrylamide with at least one other unsaturated monomer in the presence of an alkanol containing 1-6 carbon atoms, cellulose derivatives, e.g. hydroxy ethyl cellulose, materials containing active groups, e.g. the acidic groups comprising sulphonic acid, phosphoric acid, carboxylic acid or their ionisable salts, nitrogenous basic groups or ionisable salts thereof, water-solvatable polymeric polyoxyalkylene groups, outer oxidant groups, groups which contain silicon- or fluorine-based water-repellent groups, polymeric groups containing a plurality of alcoholic hydroxy radicals and polymeric groups containing a plurality of -CO-NH- radicals, thermosetting acrylic or methacrylic compositions produced from polymers or copolymers of acrylic or methacrylic acid or their esters containing functional groups such as hydroxy, carboxyl, amide and oxirane groups, and a condensation product of an amine such as melamine, urea and diazines with formaldehyde, e.g. a composition based on polyethyl acrylate and an amine-formaldehyde condensate, and methyl methacrylate-acrylic acid or methacrylic acid copolymers, e.g. those containing also ethyl acrylate and a ureido polymer complex. The polyester may be polyethylene terephthalate. The film may be drawn in the longitudinal direction at a temperature of 78 - 100C and in the transverse direction at 80-125C. The coated film may be heat set at 150-230C. The coatings may be applied as a solution in an aqueous or organic solvent or as an aqueous dispersion. The coating composition may also include antioxidants, dyes, pigments, lubricants, antiblocking agents and/or slip agents, e.g. starch, talc, zinc oxide, calcium carbonate, silica, titanium dioxide, triferric tetroxide, silicates, aluminates, alumino silicates. Scrap coated film may be re-fed together with fresh polyester to the film-forming extruder and re-extruded to form a film. Applications of the primer coatings mentioned include primer coatings for a layer of vapour impermeable coatings, e.g. of vinylidene chloride-acrylonitrile copolymer, a lacquer containing a matting agent to produce a coated film suitable for drawing office applications, or a gelatin based coating for photographic films, primer coatings to render the polyester film receptive to heat sealable coating polymers disclosed in Patent No. 1,078,813, coatings consisting of discrete particles of polymer or of inorganic materials to improve the slip properties of the surface of the film, coatings of anti-static, anti-oxidant and UV stabilizing agents.