Abstract A process for the production of a polyethylene terephthalate film characterized by carrying out heat setting after biaxial elongation so that the heat set temperature and heat set time may satisfy the following relations: ______________________________________ heat set temperature 140-213°C.
log t ≧ -0.14T + 10.99
heat set temperature 213-223°C.
log t ≧ -0.14T + 30.8
heat set temperature 223-255°C.
log t ≧ -0.0186T + 3.73
______________________________________ in which T is a heat set temperature (°C.) and t is a heat set time (min.), and thus obtaining a cleavage-free film.
Inventors
👤 Hiroshi Okuyama
👤 Hisao Takahashi
👤 Akira Hasegawa
Bibliographic Details
Application Number—
JurisdictionUS
Data Sourcegoogle_patents
Last Synchronized2026-11-07 15:02
CPC Classifications
B; B29; B29D; B29D7/00
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
117 words
A process for the production of a polyethylene terephthalate film consisting essentially of polyethylene terephthalate, said film having improved resistance to cleavage, characterized by carrying out heat setting said film consisting essentially of polyethylene terephthalate after a biaxial elongation by a factor of at least three in the lateral and longitudinal directions so that the heat set temperature and heat set time satisfy one of the following relationships: ______________________________________
heat set temperature 140-213°C
log t ≧ -0.0470T + 10.99
heat set temperature 213-223°C
log t ≧ -0.14T + 30.8
heat set temperature 223-255°C
log t ≧ -0.0186T + 3.73
______________________________________ in which T is a heat set temperature (°C) and t is a heat set time (min).
Claim 2
Dependent Claim
117 words
A process for the production of a polyethylene terephthalate film consisting essentially of polyethylene terephthalate, said film having improved resistance to cleavage, characterized by carrying out heat setting said film consisting essentially of polyethylene terephthalate after a biaxial elongation by a factor of at least three in the lateral and longitudinal directions so that the heat set temperature and heat set time satisfy one of the following relationships: ______________________________________
heat set temperature 140-213°C
log t ≧ -0.0470T + 10.99
heat set temperature 213-223°C
log t ≧ -0.14T + 30.8
heat set temperature 223-255°C
log t ≧ -0.0186T + 3.73
______________________________________ in which T is a heat set temperature (°C) and t is a heat set time (min).
Claim 3
Dependent Claim
27 words
A process for the production of a polyethylene terephthalate film as claimed in claim 1, wherein said polyethylene terephthalate has an intrinsic viscosity of more than 0.4.
Claim 4
Dependent Claim
28 words
A process for the production of a polyethylene terephthalate film as claimed in claim 1, wherein said polyethylene terephthalate has an intrinsic viscosity of between 0.58 and 0.65.