Patent GB-1371855-A (GB)
Title: Production of printed films
IPC: B41M1/30
Filed: 1972-02-02
Abstract: 1371855 Printed plastics sheets IMPERIAL CHEMICAL INDUSTRIES Ltd 5 Jan 1973 [2 Feb 1972] 4833/72 Addition to 1134876 Heading B2E A method of producing a printed film comprises, (a) subjecting a surface of an uncoated thermoplastics film to surface treatment, e.g. oxidative treatment to improve its bonding properties; (b) coating the treated surface with an interpolymerised condensation resin comprising a monoaldehyle, acrylamide or methacrylamide, and at least one other unsaturated monomer, condensation of the resin being effected in the presence of a C 1-6  alkanol so that some amino hydrogens are replaced by -ROR' groups, the R and R' groups being alkylene and alkyl groups corresponding to those of the monoaldehyde and the alkanol respectively; (c) heating the resin coated film to cure the resin so it becomes bonded to the film, and (d) applying an inked pattern to the cured resin. Optionally the condensation product is interpolymerised with at least one other unsaturated monomer. Preferably both sides of the film are coated with the condensation resin and the side opposite the inked pattern coated side is coated with a heat sealable coating or a barrier coating prior to curing the condensation resin. A transparent polymeric top-coat may be deposited on the inked pattern. The top-coat may be an acrylonitrile latex or a pre-formed polyurethane film laminated by means of a polyurethane based adhesive. Suitable treatments of the film include corona discharge, ionizing radiation, flame, or chemically with chromic, sulphuric or nitric acid, or ozone. The ink may be doped with or may be based on water, an alcohol or ketone, or nitrocellulose (optionally modified by addition of polyamide or plasticiser), polyamide, or other polymers. Examples of monoethylenically unsaturated monomers to be copolymerised with the (meth)acrylamide monoaldehyde condensation product are (meth)acrylic esters, acrylonitrile, styrene monoethyl styrene, vinyl toluene, maleic anhydride, vinyl ethers, or dienes such as butadiene or chloroprene. Up to 50% by wt. thermosetting resin, such as epoxy or melamine-formaldehyde, may be present in mixture with the condensation resin. The monoaldehyde may be formaldehyde, acetaldehyde, butyraldehyde or furfural. The resin is applied to the film as aqueous dispersion or solution. Preferred films are made of oriented and heat set polymers and copolymers of ethylene, propylene, butene, 4-methylpent-1-ene; linear polyesters such as polyethylene terephthalate and polyethylene - 1,2 - diphenoxyethane - 4,4' - dicarboxylate; and polymers and copolymers of vinyl chloride. The heat seal coating is preferably a dispersion or solution, as applied, of a copolymer of vinyl chloride with acrylonitrile and optionally other monomers such as (meth)acrylic or itaconic acid. Barrier coatings include the following polymers or copolymers: vinylidene chloride with alkyl acrylates, acrylonitrile or vinyl chloride; vinyl acetate, optionally partially hydrolised; vinyl acetate with vinyl chloride or ethylene; butadiene with acrylonitrile, styrene or methyl methacrylate, butadiene/methyl methacrylate/styrene; methyl methacrylate/methacrylic acid; vinyl chloride/ ethylene; or copolyesters of terephthalic acid and another dicarboxylic acids, e.g. sebacic, with a glycol. The barrier coating is preferably applied as an aqueous dispersion, and may include (a) inorganic or organic (including polymeric) particulate non-soluble fillers many examples of which are given, or (b) waxy additives of which many examples are given. It is stated that the condensation resin should be left to age before the printing step is performed.