Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Patent
1981-12-29
1984-02-28
Anderson, Philip E.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
264 41, 2642091, 425 67, 425817C, 521143, 521184, B29D 2700, B29F 304
Patent
active
044342500
ABSTRACT:
Method and apparatus for the production of porous tubing. One extrudes a homogeneous mixture of at least two components, one component a meltable polymer and the other component a liquid inert in relation to the polymer, both components forming a binary system which in liquid aggregate state displays a range of complete miscibility and a range with a miscibility gap, at a temperature above the separation temperature, substantially vertically upwardly using a circular slot nozzle and blowing of gas or dosing-in of liquid into the interior of the nozzle, into a bath, which displays a temperature below the separation temperature, allows the tubing to solidify, and extracts or lixiviates the tubing. Preferred embodiments include the use of water at a temperature from 15.degree. to 90.degree. C. as bath liquid; use of polypropylene as the polymer and N,N-bis-(2-hydroxyethyl)-hexadecylamine as liquid; blowing nitrogen gas into the interior of the nozzle; lixiviating with alcohol; thermally insulating the circular slot nozzle from the bath; having a non-insulated zone between the circular slot and the thermal insulation; the non-insulated zone of the nozzle having a breadth of about 0.5 to 1 mm; using thermal insulation based upon asbestos cement. The apparatus for the production of the porous tubing by extrusion of such homogeneous mixture contains a circular slot nozzle, having a circular slot and provided with means thermally insulating in relation to the bath liquid, displaying a zone without thermal insulation between said circular slot and said thermally means.
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Akzo N.V.
Anderson Philip E.
Striker Michael J.
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