COMPOSITE TUBULAR ARTICLE AND ITS PRODUCTION METHOD

摘要

A composite tubular article is used as a belt which is suitable for fixation on an image forming appts. such as a duplicating machine, partic. for heat fixation. Conventionally, a belt having a polyimide resin on the inner layer and a fluororesin on the outer layer is known as an image fixing belt but this belt involves the problems that a clear and vivid image cannot be obtd. because the thickness of each layer is not uniform and a lustreless or so called ''mat'' image cannot be obtd. due to a smooth belt surface. The present invention provides a composite tubular article consisting of a tubular inner layer made of a polyimide resin and a tubular outer layer made of a fluororesin, whereby surface coarseness of the outer peripheral surface of the fluororesin tubular outer layer is from 1-10 micron. The method comprises forming the outer layer by use of a cylinder having an inner peripheral surface having surface coarseness of 1-10 micron and forming the polyimide resin tubular inner layer on its inner peripheral surface by imidation of a polyamidic acid, or a method which comprises dipping the inner layer formed by the imidation of the polyamidic acid in a fluororesin soln. in which particles having a particle dia. of up to 5 micron are dispersed or spraying the soln. to the inner layer to form the outer layer.