A highly transparent composite film and method of preparing the same, and a coating for use in preparing the composite film

摘要

A coating composition comprises a lacquer containing a major proportion of a resinous copolymer of from 75% to less than 92% by weight of vinylidene chloride and at least one other monomer copolymerizable therewith, and from 0.2 to 2%, based on the weight of the coating, of solid particles having a size of from 0.1 to 5 microns of a resinous copolymer of at least 92% and up to 99% by weight of vinylidene chloride and at least one other monomer copolymerizable therewith. Specified copolyizable monomers are acrylonitrile acrylamide, vinyl chloride, vinyl acetate, ethyl acrylate, butyl acrylate, ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, stearyl methacrylate, acrylic acid, methacrylic acid, and itaconic acid. The preferred lacquer-solvents contain from 5-40% by weight solids plus an organic solvent or solvent-diluent mixture, e.g. tetrahydrofuran, methyl ethyl ketone, ethyl acetate, butyl acetate, acetone, ethyl alcohol, butyl alcohol, cellosolves, heptane, benzene, toluene, and xylene. The resinous copolymers may be prepared in any known manner e.g. emulsion polymerization. In an example, copolymers of over 92% by weight vinylidene chloride and a remainder of acrylonitrile were prepared by emulsion polymerization. The aqueous copolymer dispersions were adjusted to pH 6 with ammonia and were dried to a white solid, which was ball-milled with butyl acetate to the requisite particle size. The paste was added to a stock vinylidene chloride copolymer coating lacquer consisting of tetrahydrofuran-toluene solvent, a copolymer of 90% by weight vinylidene chloride and 10% by weight acrylonitrile, hydrogenated castor oil, and a liquid resinous interpolymer of phthalic anhydride, adipic acid and diethylene glycol in castor oil carrier.ALSO:A coated film comprises a clear, non-fibrous, organic base film and a solvent-laid coating on at least one side thereof, characterized in that the coating comprises a major proportion of a resinous copolymer of from 75% to less than 92% by weight of vinylidene chloride and at least one other monomer copolymerizable therewith, and from 0,2-02%, based on the weight of coating, of solid particles having a size of from 0,1-5 microns of a resinous co-polymer of at least 92% and up to 99% by weight of vinylidene chloride and at least one other monomer coplymerizable therewith. The organic base film may be cellulosic (e.g. regenerated cellulose, hydroxyalkylcellulose ether, alkyl cellulose or cellulose esters) or synthetic resinous (e.g. polyolefins or polyesters). Monomers copolymerizable with vinylidene chloride include acrylonitrile, acrylamide, vinyl chloride, vinyl acetate, ethyl acrylate, butyl acrylate, ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, stearyl methacrylate, acrylic acid, methacrylic acid, and itaconic acid. The solid particles may be obtained by the drying of an emulsion polymerization mixture which contains the 92-99% vinylidene chloride copolymer, e.g. by spray drying. The particles may be slurried with an organic liquid to form a paste which is distributed in the lacquer containing the 75% to less than 92% vinylidene chloride copolymer used to coat the film. The solvents used for the coating lacquer may be used to prepare the particle slurry.