| 摘要 |
Compositions for priming polyethylene surfaces comprise (1) an aqueous latex of an internally plasticized copolymer of 70 to 95 weight per cent vinylidene chloride and 5 to 30 weight per cent monomers copolymerizable therewith; (2) a stabilized silica sol; and (3) a modified rosin, the total solids being 10 to 50 weight per cent of the composition and comprising 10 to 65% latex solids, 10 to 50% colloidal silica and 15 to 80% modified rosin. The vinylidene chloride may be copolymerized with vinyl esters, alkyl vinyl ethers, acrylic esters and methacrylic esters, optionally together with acrylic acid, itaconic acid, aconitic acid, acrylonitrile and methacrylonitrile. The silica sol may be a sodium stabilized aqueous sol, and may also contain alumina. The modified rosin may be polymerized, hydrogenated and/or disproportionated rosin dispersed in ammonium hydroxide or sodium hydroxide. The compositions may be applied to polyethylene films or polyethylene coated papers.ALSO:Modified polyethylene films are coated with priming compositions comprising (1) an aqueous latex of an internally plasticized vinylidene chloride copolymer containing 70-95 weight per cent of vinylidene chloride and 5-30 weight per cent of monomers copolymerizable therewith, (2) a stabilized silica sol, and (3) a modified rosin, the total solids being 10-50 weight per cent of the composition and comprising 10-65% latex solids, 10-50% colloidal silica and 15-80% modified rosin. The polyethylene film may be unsupported or may be applied to paper by extrusion coating, and may be modified to increase adhesion by treatment with electrostatic discharge, ultra violet light, an oxidizing flame or a matte roller. The coating may be applied by an air knife, size press, trailing blade, transfer roll, reverse roll, roller coater, gravure, bead coat, metering bar, spray coater or curtain coater. The vinylidene chloride may be copolymerized with vinyl esters, vinyl alkyl ethers, acrylic esters or methacrylic esters, optionally together with acrylic acid, itaconic acid, aconitic acid, acrylonitrile or methacrylonitrile. The silica sol may be a sodium stabilized aqueous sol, and may also contain alumina. The modified rosin may be polymerized, hydrogenated and/or disproportionated rosin dispersed in ammonium hydroxide or sodium hydroxide. Top coats of latices of internally plasticized vinylidene chloride copolymers, optionally thickened with gums, cellulose ethers or poylvinyl alcohol, may be applied to the primed surfaces. |
