Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Shaping by extrusion
Patent
1991-07-22
1992-08-18
Tentoni, Leo B.
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
Shaping by extrusion
2642358, 2642902, B29C 5514
Patent
active
051397277
ABSTRACT:
The present invention relates to a process for producing a biaxially oriented polyester film. The process is carried out using the following steps: (a) stretching an amorphous film substantially comprising polyethylene terephthalate 1.2 to 4.0 times in the machine direction by single-stage or multi-stage process to obtain a film having an index of birefringence of 1.times.10.sup.-3 to 2.5.times.10.sup.-2 ; (b) stretching the thus obtained film 1.1 to 3.5 times in the machine direction by single-stage or multi-stage process of 3.0.times.10.sup.-2 to 8.0.times.10.sup.-2 without cooling the film to the glass transition temperature thereof or below; (c) cooling the thus obtained film to the glass transition temperature thereof or below; (d) heating the thus obtained film to the glass transition temperature or higher and stretching the film in the machine direction by a single-stage or multi-stage process at a stretching ratio which brings the overall stretching ratio of 4.0 to 9.0 times; and (e) stretching the thus obtained film at least 3.2 times in the transverse direction. According to the method of the present invention, a biaxially oriented polyester film which is excellent in thickness uniformity and flat and slippery properties can be easily produced and high-speed production thereof is possible, therefore, the present invention has a great industrial value.
REFERENCES:
patent: 4059667 (1977-11-01), Pangonis
patent: 4370291 (1983-01-01), Kazama et al.
English Translation of Japanese Reference (Kokai) 58-78,729 (Published May 1983).
English Translation of Japanese Reference (Kokai) 60-228,123 (Published Nov. 1985).
Abstract of Japanese Reference (Kokai) 54-8,672 (Jan. 1979).
Abstract of Japanese Reference (Kokai) 58-118,220 (Jul. 1983).
Database WPIL No. 86-327982 (50), Derwent Abstract.
Database WPI, No. 78-12792A (07) Derwent Abstract.
Database WPIL, No. 83-28573K (12), Derwent Abstract.
Fukuda Yujiro
Miki Takatoshi
Tomitaka Kichinojyo
Utsumi Shigeo
Conlin David G.
Daifoil Company, Limited
Resnick David S.
Tentoni Leo B.
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