Patent ID: 6062228
Filing Date: 2000-05-16
Classification: A24D,Y10S

Abstract:
A method for manufacturing biodegradable filter elements comprising:(a) continuously supplying a mixture to an extruder, the mixture consisting essentially of a starch-based polymer selected from the group consisting of native starches, modified starches, and thermoplastic starch polymers, at least one synthetic polymer selected from the group consisting of polyvinyl alcohol, polyester amides, polyester urethanes, aliphatic polyesters, aromatic polyesters, and copolymers of aliphatic polyesters and aromatic polyesters, optionally a flow auxiliary, and optionally a blowing agent, wherein the starch-based polymer supplied to the extruder comprises starch that has been initially predried to below its natural water content;(b) heating and kneading the mixture under conditions so as to form a thermoplastic melt;(c) extruding the thermoplastic melt through a die to form an extrudate of the thermoplastic melt;(d) causing the extrudate to develop a porous configuration;(e) compressing the extrudate and forming an endless filter rod; and(f) wrapping the filter rod and forming single filter elements.