Process for extruding thermotropic liquid crystalline polymers
AssigneeCelanese Corporation
InventorYoshiaki Ide
Life of this patent
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Abstract
Provided is a process for the extrusion of shaped articles which comprises extruding a thermotropic liquid crystal polymer through a short land or preferably no land die, and with subsequent drawdown of the extruded profile being such as to render a drawdown ratio of less than 4, and preferably about 1. Such extrusion of liquid crystal polymers in accordance with the present invention can consistently and reproducibly provide one with an article of high mechanical properties, and thus, particular advantage is found in employing the process to extrude an article of cross-sectional dimensions which must closely approximate those of the extrusion die without sacrificing high mechanical properties.
Claims17
A process for extruding a polymer to form shaped articles comprising the steps of:
- (a) providing thermotropic liquid crystal polymer in melt form,
- (b) extruding said liquid crystal polymer through an extrusion die having a converging entry section and a land length such that the ratio of land length (L) to die orifice diameter (D) is less than 2, and
- (c) subjecting the extrudate to a drawdown using a haul-off or take-up device such that the drawdown ratio is less than 4.
The process for extruding a polymer to form shaped articles comprising the steps of:
- (a) providing thermotropic liquid crystal polymer in melt form,
- (b) extruding said liquid crystal polymer through an extrusion die having a converging entry section and substantially no land portion so that the ratio of land length (L) to die orifice diameter (D) is about zero, and
- (c) subjecting the extrudate to a drawdown such that the drawdown ratio is in the range of from about 1 to 2.
A process for extruding a polymer to form a shaped article having high mechanical properties and substantially the same cross-sectional dimensions as a die orifice used to extrude the article, said process comprising
- (a) providing thermotropic liquid crystal polymer in melt form,
- (b) extruding said liquid crystal polymer through an extrusion die which has substantially no land portion, and
- (c) subjecting the extrudate to a drawdown such that the drawdown ratio is about 1.
Dependencies are inferred from the claim text.