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:
Oct. 19, 1999
Filed:
Apr. 22, 1997
Applicant:
Inventors:
Assignee:
Mitsui Chemicals, Inc., Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
B29C / ;
U.S. Cl.
CPC ...
521143 ; 21050027 ; 21050036 ; 21050042 ; 264 41 ; 2642103 ; 2642104 ; 2642105 ; 2642107 ; 264211 ; 26421113 ; 2642112 ; 4283155 ; 521 64 ;
Abstract
A process for producing a porous film of polypropylene comprises subjecting (1) an air-impermeable biaxially stretched film of polypropylene resin comprised predominantly of polypropylene having a crystallinity of at least 40% or (2) an air-impermeable inflation film of polypropylene resin comprised predominantly of polypropylene having a crystallinity of at least 46.5%, in the substantial absence of a plasticizer or a solvent, to a thermal treatment in the presence of a first liquid substantially incapable of dissolving the film while fixing the film in two orthogonal directions for making the film porous.