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:
Jun. 29, 2010
Filed:
Mar. 23, 2007
Kyoko Hino, Sodegaura, JP;
Toshihiko Suzuki, Niihama, JP;
Hiroaki Takahata, Ichihara, JP;
Sumitomo Chemical Company, Limited, Tokyo, JP;
Abstract
The present invention provides a method for producing a retardation film of a polypropylene resin, the method comprising subjecting a film of a polypropylene resin to longitudinal stretching and transverse stretching which are performed sequentially, wherein the transverse stretching comprises the following steps, and a polypropylene resin retardation film which is obtained by such a method and has both a high axial retardation and a uniform retardation: a step of preheating the film at a preheating temperature which is equal to or higher than the melting point of the polypropylene resin; a step of stretching the preheated film in the transverse direction at a stretching temperature which is lower than the preheating temperature; and a step of heat setting the film stretched in the transverse direction.