US4610833A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for preparing biaxially stretched polyester films
Assignee: Diafoil Co Ltd
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Filing: 1983-09-14
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Granted: 1986-09-09
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Expires: 2003-09-14
Abstract
Abstract PCT No. PCT/JP83/00306 Sec. 371 Date Apr. 18, 1984 Sec. 102(e) Date Apr. 18, 1984 PCT Filed Sep. 14, 1983.A process for preparing biaxially stretched polyester films comprising stretching an unstretched polyester film longitudinally so that the DELTA n value becomes 0.030-0.055, further stretching the film in the same direction so that the DELTA n value does not exceed 0.08 and the &upbar& n value becomes 1.600 or less, and thereafter stretching the film transversely. The films prepared by the process of this invention are flat and slippery, less breakable and less uneven in thickness, and are especially suitable as the base film for video recording tapes.
Inventors
- 👤 Tateo Kanesaki
- 👤 Shigeo Utsumi
- 👤 Kichinojyo Tomitaka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 17:15
CPC Classifications
C; C08; C08J; C08J5/00; C08J5/18; B; B29; B29C; B29C55/00; B29C55/02; B29C55/04; B29C55/06; B29C55/065; B29C55/10; B29C55/12; B29C55/14; B29C55/143; G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/739; G11B5/73923; G11B5/73927; B29K; B29K2067/00; C08J2367/00; C08J2367/02
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
118 words
A process for preparing a uniformly flat and slippery biaxially stretched film, which comprises the steps of: (a) subjecting an unstretched polyester film to a first stage single longitudinal stretching to attain a Δn value of 0.030-0.055, (b) subjecting said polyester film to a later stage longitudinal stretching at a temperature of from 95° C. to 150° C. to attain a Δn value of not more than 0.080, an n of not more than 1.600, and a stretching ratio of from 1.05 to 1.7, (c) stretching said polyester film transversely, and (d) finally, heat setting said polyester film at a temperature between 180° C. and 245° C., wherein between steps (c) and (d) there are no intervening steps.
Claim 2
Dependent Claim
118 words
A process for preparing a uniformly flat and slippery biaxially stretched film, which comprises the steps of: (a) subjecting an unstretched polyester film to a first stage single longitudinal stretching to attain a Δn value of 0.030-0.055, (b) subjecting said polyester film to a later stage longitudinal stretching at a temperature of from 95° C. to 150° C. to attain a Δn value of not more than 0.080, an n of not more than 1.600, and a stretching ratio of from 1.05 to 1.7, (c) stretching said polyester film transversely, and (d) finally, heat setting said polyester film at a temperature between 180° C. and 245° C., wherein between steps (c) and (d) there are no intervening steps.
Claim 3
Dependent Claim
23 words
The process of claim 1, wherein said first stage single longitudinal stretching is conducted at a temperature from 80° C. to 130° C.
Claim 4
Dependent Claim
21 words
The process of claim 1, wherein said single longitudinal stretching is characterized by a stretching ratio of from 2.0 to 5.0.
Claim 5
Dependent Claim
14 words
The process of claim 1, wherein said n value is not more than 1.595.
Claim 6
Dependent Claim
14 words
The process of claim 1, wherein said stretching ratio is from 1.1 to 1.6.
Claim 7
Dependent Claim
18 words
The process of claim 1, wherein said film is stretched transversely by a factor of 2.5 to 4.5.
Claim 8
Dependent Claim
21 words
The process of claim 1, wherein said film is stretched transversely at a temperature of from 80° C. to 160° C.
Claim 9
Dependent Claim
23 words
The process of claim 1, wherein said polyester film is a polyester which contains at least 80% by weight of ethylene terephthalate units.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-09-08 | 1990-03-10 | 1990-09-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-09-08 | 1994-03-10 | 1994-09-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-09-08 | 1998-03-10 | 1998-09-09 | $7700.00 | Window Closed / Lapsed |