| 摘要 |
803,191. Coated cellulose films. DU PONT DE NEMOURS & CO., E.I. Nov. 22, 1955 [Nov. 22, 1954], No. 33490/55. Class 140. A packaging film comprises a base film of regenerated cellulose having a subcoat of a copolymer obtained from up to 70 per cent vinylidene chloride and 30-100 per cent of an alkyl acrylate in which the alkyl group contains at least 2 carbon atoms, and a top coat of a copolymer obtained from 80-97 per cent vinylidene chloride and 3-20 per cent of at least one polymerizable mono-olefinic monomer. The Specification states that the most useful monomers are those of general formula CH 2 = C(R)X, where R may be hydrogen, halogen or a saturated aliphatic aliphatic radical and X may be chosen from the following groups: halogen, cyanide, carboxyl, phenyl, -CO(OR<SP>1</SP>), -CO(R<SP>1</SP>), -CHO, -OC 6 H 5 , -CONH 2 , -CONHR<SP>1</SP> and -CONR<SP>1</SP> 2 , where R<SP>1</SP> is alkyl. Many such compounds are listed in the Specification but special emphasis is placed on the use of an alkyl acrylate, e.g. methyl acrylate, or acrylonitrile The base film of regenerated cellulose may be pretreated before coating by either softening with ethylene glycol or impregnating with a urea-guanidine-formaldehyde resin which may alternatively be incorporated in material from which the film is originally cast, or both. The coating compositions, which may be applied by conventional methods from either aqueous dispersions or solutions of the polymers in organic solvents, preferably contain from 0.5 to 3 per cent by weight based on the total weight of the two components of the polymer of an unsaturated aliphatic acid, e.g. acrylic, methacrylic or itaconic acids. Other components may include dyes, pigments, delustrants and plasticizers. Specifications 654,342 and 684,105 are referred to. |
