| 摘要 |
1503013 Coated films RHONE-POULENCE INDUSTRIES 7 Feb 1975 [8 Feb 1974] 5332/75 Heading B2E [Also in Division B5] A composite film comprises at least two superposed layers adhered together one of the layers consisting of a copolymer of tetrafluoroethylene and hexafluoropropylene and the other layer consisting of a polyamideimide comprising recuring units of the formula in which R is a trivalent organic radical containing at least two carbon atoms and A is a divalent radical containing at least one benzene ring, the polyamide-imide layer possessing an essentially uniplanar axial structure. R may have the formula: and A may be a m-phenylene, p-phenylene or p, p'-diphenylene radical or a radical of the formula: in which B is -O-, -CH 2 -, -C(CH 3 ) 2 -, -SO 2 - or -N=N-. The layer of tetrafluoroethylene/hexafluoropropylene copolymer which may contain 5-50% by weight of hexafluoropropylene, may be subjected to electric discharge treatment prior to bonding to the polyamide-imide layer. Both layers of polymer may have a thickness of 5-500Á. A composite film may be produced by stretching (e.g. by a ratio of 1.1 to 1.6) a primary film consisting of the layer of tetrafluoroethylene/hexafluoropropylene copolymer and layer of polyamideimide containing at least 1% by weight of solvent in at least one direction at a temperature of 100‹-350‹C whilst preventing shrinkage in any direction and then subjecting it to a supplementary heat treatment at 100‹- 350‹C. The primary film may be formed by casting a solution of the polyamide-imide in a polar organic solvent onto the layer of fluorinated polymer and evaporating the solvent to a content of at least 1% by weight. The composite filmsmay be used to cover electrical conductors. |
