| 摘要 |
801,992. Coated regenerated cellulose films. DU PONT DE NEMOURS & CO., E.I. Dec. 1, 1955 [Dec. 9, 1954], No. 34471/55. Class 140. A packaging film comprises a base film of regenerated cellulose having at least one surface coated with a subcoating of an unhardened elastoprene, elastolene or elastothiomer, and with a top coating of a copolymer obtained from 80-97 per cent of vinylidene chloride and 3-20 per cent of at least one other polymerizable mono-olefinic manomer. The Specification defines an " elastoprene " as a derivative of butadiene, e.g. butadiene rubbers, piperylene rubbers, isoprene rubbers, dimethylbutadiene rubbers and haloprene rubbers; an " elastolene " as including polymers such as polyisobutylene; and an " elastothiorner " as including the polyalkylene sulphides. The polymerizable mono-olefinic monomers preferred are those of general formula CH 2 =C(R)X, where R is halogen, hydrogen or a saturated aliphatic radical, and X may be selected from the following groups : halogen, cyanide, phenyl, carboxyl, -CO(OR<SP>1</SP>), -CO(R<SP>1</SP>), -CHO, -OC 6 H 4 , -CONH 2 , -CONHR<SP>1</SP> and -CONR<SP>1</SP> 2 , where R<SP>1</SP> is alkyl. Many examples of such compounds are listed in the Specification. It is stated that the preferred compounds of this type are alkyl acrylates or acrylonitrile. The top coating layer may also contain a small percentage of an unsaturated aliphatic acid, e.g. acrylic, methacrylic or itaconic acid, and dibutyl phthalate other plasticizers, pigments, dyes and delustrants may be incorporated in the coatings which may be applied by conventional methods from aqueous dispersions or solutions of the polymers in organic solvents. The base film may be softened prior to coating by immersion in ethylene glycol or guanidine-urea-formaldehyde polymer. The resulting films are heat sealable and may be used as packaging materials. Specifications 590,698, 654,342 and 684,105 are referred to. |
