Method for forming a thermoplastic composition that contains a plasticized starch polymer

摘要

A method and system for melt processing a thermoplastic composition that contains a starch and plasticizer is provided. The composition is melt blended and extruded through a die to form an extrudate, which is thereafter cooled using a multi-stage system of the present invention that includes at least one water-cooling stage and at least one air-cooling stage. More particularly, the extrudate is initially contacted with water for a certain period time so that it becomes partially cooled and solidified on its surface. After the water-cooling stage(s), the extrudate is also subjected to at least one air-cooling stage in which a stream of air is placed into contact with the extrudate.

主权项

1. A method for forming a thermoplastic starch-based composition, the method comprising:
melt extruding a thermoplastic composition through a die to form an extrudate, wherein the thermoplastic composition comprises a starch polymer and a plasticizer, wherein the plasticizer is a polyhydric alcohol or a sugar alcohol; subjecting the extrudate to at least one water-cooling stage in which the extrudate is contacted with water for a first period of time; and thereafter, subjecting the water-cooled extrudate to at least one air-cooling stage in which the extrudate is contacted with air for a second period of time, wherein the air-cooled extrudate has a moisture content of from about 1,000 to about 10,000 parts per million, wherein a film formed from the thermoplastic starch-based composition exhibits a percent strain at break in the cross-machine direction of about 550% or more.