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:
Jul. 28, 1992
Filed:
Oct. 31, 1991
Applicant:
Inventors:
Mao Xu, Beijing, CN;
Shiru Hu, Beijing, CN;
Jiayu Guan, Beijing, CN;
Xianming Sun, Beijing, CN;
Wei Wu, Beijing, CN;
Wei Zhu, Beijing, CN;
Xian Zhang, Beijing, CN;
Zimian Ma, Beijing, CN;
Qi Han, Beijing, CN;
Shangqi Liu, Beijing, CN;
Assignee:
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
B29C / ; B29C / ;
U.S. Cl.
CPC ...
521143 ; 2642884 ; 2642902 ; 521918 ;
Abstract
Polypropylene microporous films characterized by having a porosity of 30-35%, an average pore size of 200-800 Angstroms, a permeation coefficient for nitrogen of 1-5.times.10.sup.-3 ml/cm sec atm and a tensile strength of greater than 60 MPA in all directions within the film plane are prepared by the consecutive steps of biaxial stretching a non-porous starting film of high .beta.-crystal content and heat setting the stretched film.