| 摘要 |
626,536. Compound sheet material. BRITISH CELLOPHANE, Ltd. Feb. 14, 1947, No. 4411. Convention date, Feb. 19, 1946. [Class 140] A continuous moisture-proofing coating consisting essentially of a vinylidene chlorideacrylonitrile copolymer is anchored to a non- fibrous base film of regenerated cellulose by an intermediate layer comprising a heat-hardened alcohol-modified methylol melamine waterinsoluble thermosetting resin and nitrocellulose, the ratio between the resin and the nitrocellulose being within the range 20: 80 to 75: 25. The modifying alcohol is preferably a monohydric one containing from 3 to 8 carbon atoms, n-butyl alcohol being preferred. The resin composition layer may be obtained by applying a coating of a solution in an organic solvent of monomeric or incompletely condensed alcoholmodified methylol melamine and nitrocellulose which may contain an acidic condensing agent such as maleic acid or p-toluene sulphonic acid, further condensation of the former to a heathardened form taking place during drying, as by exposure to hot air. The vinylidene chloride-acrylonitrile copolymer coating may also be applied in the form of a solution in-an organic solvent. Definitions of the term " moisture-proof" and a description of the method of testing the heat-seal bond strength are given. Specifications 601,926, 622,481 and U.S.A. Specification 2,278,415 are referred to. |
