Porous tubing
US4434250A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 29, 1981 |
| Grant date | Feb 28, 1984 |
| Priority date | — |
| Expiry date | Dec 29, 2001 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC08J2201/0546
- WIPO fieldOther special machines
- WIPO sectorMechanical engineering
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 t…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.