Xerox Corporation

Richard A Cairncross

Kent J Evans

Robert F Dunham

Timothy J Leenhouts

Warren R Smith

Barbara D Ceglinski

A dryer with zone temperature controls for drying thick polymer-solvent layers on a substrate. The dryer is formed with several heating elements located in an air duct. The cool air is heated a specific amount as it passes each heating element. The heated air is then applied to the polymer-solvent solution on the substrate in a continuous fashion so that the polymer-solvent solution slowly heats up as it passes through the drying apparatus. The preferred design is to ensure a zone residence time of less than 10 seconds and a web heating rate of 10.degree. F./second or less. Most preferred design is a zone residence time less than 5 seconds and a heating rate less that 5.degree. F./second. The dryer is designed to have a continuous temperature gradient, especially in the critical later stages of drying when the solvent content of the film is less than 20%.

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Saint Paul, MN, United States of America

Richard A Cairncross