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:
Dec. 03, 1991
Filed:
Aug. 17, 1989
Hiroshi Takasu, Chiba, JP;
Susumu Arase, Chiba, JP;
Junichiro Yokota, Chiba, JP;
Kazuo Nakayama, Ibaragi, JP;
Chisso Corporation, both of, JP;
Agency of Industrial Science and Technology, both of, JP;
Abstract
The present invention provides a process for preparing rolled heat-treated films or sheets of a crystalline thermoplastic resin in which heat shrinkage is notably improved, formability is excellent and tensile strength in a transverse direction is increased. The process of the present invention comprises the steps of rolling a crystalline thermoplastic resin material between at least one pair of rolls at a temperature which is lower than the melting point of the resin material but higher than room temperature, and then successively subjecting the resin material to a heat treatment at a temperature which is higher than the rolling temperature but lower than the melting point of the resin material. The heat treatment is carried out for a time (t: seconds) satisfying the formula ##EQU1## wherein d is the thickness (mm) of the rolled films or sheets, r is the thickness reduction rate of the rolled films or sheets, Tr is the rolling temperature (.degree.C.), Ta is the heat treatment temperature (.degree.C.), and Tm is the melting point (.degree.C.) of the crystalline resin.