Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Layered – stratified traversely of length – or multiphase...
Patent
1983-07-05
1984-11-27
Thurlow, Jeffery
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
Layered, stratified traversely of length, or multiphase...
264176F, 264201, 425 97, 425107, B29F 306
Patent
active
044850620
ABSTRACT:
Making polymeric extrudates having a smooth surface by feeding a molten polymeric core material through a die cavity wherein a portion of the wall of the die cavity is a rigid microporous structure located upstream from a narrowed flow passage of the die cavity, the microporous structure having a substantially uniform pore size, simultaneously forcing under pressure through the microporous structure about 0.03-10%, based on the total weight of the extrudate, of a low viscosity liquid to form a sheath on the molten polymeric core material thus displacing the polymeric core material before the resulting sheath-core composite enters the narrowed flow passage of the die cavity said process conducted under conditions to produce a pressure drop across the microporous structure of at least 0.10 MPa more than the pressure applied on the polymeric core material.
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Dawes James W.
Ryan Donald J.
E. I. Du Pont de Nemours and Company
Thurlow Jeffery
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