Microporous hollow fiber and process and apparatus for preparing such fiber
First Claim
1. A microporous polyolefinic hollow fiber having:
- (a) an average wall thickness in the range of from about one micron to about 75 microns;
(b) a coefficient of variation in wall thickness throughout a cross-section taken perpendicular to the axis of the fiber of less than about 20%;
(c) an average inner diameter in the range of from about 5 microns to about 1500 microns;
(d) a coefficient of variation in inner diameter throughout a cross-section taken perpendicular to the axis of the fiber of less than about 8%;
(e) a substantially uniform porosity across the circumference of said fiber as determined by the average ratio of the minimum pore density to the maximum pore density around the circumference of said fiber of less than about 3;
1;
(f) an oxygen flux of at least 100 cc/cm2 -min. at 10 p.s.i.g.; and
(g) an average pore size as measured by electron micrograph of from about 50 to about 2000 Angstroms in width and from 500 to 10,000 Angstroms in length.
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Accused Products
Abstract
The present invention provides microporous hollow fiber with improved structural and performance characteristics and a process and apparatus for preparing the improved fiber. The microporous hollow fiber possesses substantially uniform wall thickness, cross-sectional dimensions and porosity. Such characteristics are obtained by melt spinning hollow fiber precursor under defined conditions in a substantially vertically upward direction and subjecting the precursor to a symmetrical quenching step which may be achieved using a hollow annular structure surrounding the precursor. The structure, which is connected to a source of gas, has one or more openings on its inner surface that distribute the gas against the precursor in a substantially uniform manner.
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Citations
5 Claims
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1. A microporous polyolefinic hollow fiber having:
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(a) an average wall thickness in the range of from about one micron to about 75 microns; (b) a coefficient of variation in wall thickness throughout a cross-section taken perpendicular to the axis of the fiber of less than about 20%; (c) an average inner diameter in the range of from about 5 microns to about 1500 microns; (d) a coefficient of variation in inner diameter throughout a cross-section taken perpendicular to the axis of the fiber of less than about 8%; (e) a substantially uniform porosity across the circumference of said fiber as determined by the average ratio of the minimum pore density to the maximum pore density around the circumference of said fiber of less than about 3;
1;(f) an oxygen flux of at least 100 cc/cm2 -min. at 10 p.s.i.g.; and (g) an average pore size as measured by electron micrograph of from about 50 to about 2000 Angstroms in width and from 500 to 10,000 Angstroms in length. - View Dependent Claims (2, 3, 4, 5)
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Specification