Composite material containing polyester layer having improved thermal and / or ildbestandighed for use as or in electrical insulating materials and a process for its preparation

摘要

1398914 Plastics laminate HOECHST AG 19 Oct 1972 [21 Oct 1971] 48209/72 Heading B5N [Also in Division B2] A laminate includes a polyester base film having on one or both surfaces a covering layer of an aromatic polyamide, polyamideimide or polyimide and between the base film and a covering layer an intermediate layer of the reaction product of at least one aromatic polyisocyanate with at least one epoxide resin of formula where X is an arylene radical which may be of formula or (Hal=Br or Cl) or or an aromatic diacyl radical, which may be -OC-C 6 H 4 -CO-, where n is #10 and nSP1/SP is 2-8. The base film may be of polyethylene terephthalate or a co-condensate or mixture thereof with other polyesters and may be uni- or bi-axially stretched and/or heat set. It may be a flat or tubular film, may be roughened by sand-blasting prior to coating or may be surface treated by chemical or flame oxidation or by corona discharge. The covering layer or layers may particularly be of a polyamide-imide incorporating heterocyclic units of formula which polymer may be produced from trimetallic acid and an aromatic amine. The intermediate layer may be applied to the base film as a solution by dipping, spraying or flow coating or by means of a gravure roller, followed by optional storing. The covering layer or layers are then applied from solution or dispersion, by means of a flow coater or by extrusion coating in the gel or melt form, or as preformed films using heat and/or pressure.