| 摘要 |
1,151,843. Coated sheet material. AVISUN CORP. 16 March, 1966 [30 March, 1965], No. 11472/66. Heading B2E. [Also in Divisions B5 and C3] Clear, heat-sealable, flexible, composite sheets having excellent blocking and' slip characteristics are prepared by coating, on at least one side, an oriented, preferably non- fibrous, thermoplastic base sheet or film, with an aqueous composition containing (1) an interpolymer of a C 1 -C 4 -alkyl methacrylate, a C 1 -C 4 -alkyl acrylate, and acrylic, methacrylic or itaconic acid, (2) an adduct of rosin (i.e. wood or gum rosin or an equivalent material) and an alpha, beta-ethylenically unsaturated dicarboxylic acid or anhydride, or a partial ester of said adduct with a polyhydric alcohol, and (3) a paraffin wax or a microcrystalline hydrocarbon composition. The aqueous composition may additionally include an emulsifier or a water-dispersible clay. The base sheet material may be a mono- or biaxially oriented film of polypropylene, polyethylene, polyethylene terephthalate or a polycarbonate. Preferably, the base material is pretreated to improve adhesion of the coating, e.g. by application of a thin coating of a known anchoring resin, by an acid of oxidisareatment, or by an electric discharge treatment. In an Example, a polypropylene film, which has been subjected to a corona discharge, is (a) coated on one side with a gravure coating head to provide 1.5g (dry weight) of coating per sq. m. and (b) coated on both sides using a two station gravure to provide a coating of 3 g/sq. m. |
