CONDUCTIVE COATING FILMS BASED ON LOW-DENSITY IN2O3 POWDERS AND POLYMER LATEXES

Several kinds of conductive coating films were prepared from a low-den sity indium(III) oxide powder (which was employed because it provides a much higher volume for the same weight) and polymer latexes. The low -density In2O3, which is an electrically conductive pigment, was prepa red by pyrolysis followed by the combustion of water-swellable polymer microspheres imbibed with In(NO3)(3), the precursor of In2O3. Either acrylamide/N,N'-methylenebisacrylamide or poly(vinylalcohol)/glutaricd ialdehyde was used to generate spherical hydrogel particles. The polym er latexes with which the In2O3 was mixed had a soft core and a hard s hell structure to ensure that the coating film has suitable mechanical properties in addition to conductivity. Acrylonitrile/butadiene/styre ne copolymer ABS or acrylonitrile/butylacrylate/styrene copolymer ABAS latexes were used as binders for the conductive pigment. The powder c oating followed by hot pressing, the water-borne coating consisting of low-density In2O3 and polymer latexes followed by curing, or the coll oidal dispersion coating was used to deposit flexible conductive coati ng films on polyester sheets. The conductive pigment density and the p olymer latexes' size and flowability are the factors that affect the c haracteristics of the film. We found that the colloidal suspension coa ting procedure based on ABAS latexes achieves better electrical and me chanical properties for the coating films. (C) 1996 John Wiley & Sons, Inc.