Abstract: A conductive polyester-based alloy sheet having three layers laminated together by co-extrusion, which comprises one substrate layer and two surface layers, wherein the surface layers are conductive and comprise polyester, acrylonitrile-butadiene-styrene (abbreviated as ABS) and/or polystyrene (abbreviated as PS), a compatibilizer, and a toughening agent, wherein the surface layers have a surface conductivity of not more than 10.sup.8 ohms. The melt flow index of the material for the conductive layers during the extrusion step is not less than 5.0 g/min (loading, 10 Kg; temperature, 250.degree. C.). The substrate layer is made from acrylonitrile-butadiene-styrene and/or polystyrene.

Abstract: A conductive polyester sheet having three layers, comprising one substrate layer and two surface layers, laminated together by co-extrusion is provided. All the three layers are made from polyester and/or copolyester, and the surface layers further contain carbon black and thus are useful as conductive layers. The sheet has a surface conductivity of not more than 10.sup.8 ohms and the flow index of the material for the conductive layers during the extrusion step is not lower than 60 g/min (loading, 2160 g; temperature, 275.degree. C.).

Abstract: A black masterbatch for polyester polymer consisting of:(a) 25-99.7% of polyester polymer by weight;(b) 0.1-20% of dispersive second polyester by weight and/or 0.1-15% EVA by weight; and(c) 0.1-40% of carbon black by weight;whereby the black masterbatch can be easily manufactured by a simple process without polluting the environment.