The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 03, 1993
Filed:
Feb. 06, 1992
Jun Kamo, Otake, JP;
Takayuki Hirai, Otake, JP;
Hiroshi Takahashi, Otake, JP;
Kenji Kondou, Otake, JP;
Mitsubishi Rayon Co., Ltd., Tokyo, JP;
Abstract
A porous polypropylene hollow fiber membrane of large pore diameter which have (a) rectangular pores formed by microfibrils that are oriented in the lengthwise direction of the fibers and joint portions that are composed of stacked lamellae, the pores being contiguous with each other from the inner wall surface to the outer wall surface of the hollow fiber membrane to form a stacked, multicellular structure, (b) an average pore diameter ranging from greater than 1 .mu.m up to 10 .mu.m as measured with a mercury porosimeter, (c) a porosity of 70 to 95%, and (d) an air permeability of not less than 4.times.10.sup.5 l/m.sup.2 .multidot.hr.multidot.0.5 atm can be produced by melt-spinning polypropylene, annealing the resulting unstretched hollow fiber under specific conditions, and then cold-stretching and hot-stretching the annealed hollow fiber under specific conditions.