US4587071A
Expired / Lapsed
US
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Production of polyethylene terephthalate film for magnetic recording
Assignee: Toray Industries Inc
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Filing: 1985-06-24
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Granted: 1986-05-06
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Expires: 2005-06-24
Abstract
Abstract The present invention relates to a polyethylene terephthalate film having the sum of F-5 values in longitudinal and transverse directions of 3500 to 5000 kg/cm 2 , absolute heat shrinkages in longitudinal and transverse directions at 100° C. of up to 2.5% and amorphous orientation factor of -1.5 to 0.5, a process for the production thereof and a magnetic recording medium containing the film as a base. The polyethylene terephthalate film useful as a magnetic recording medium having super high-tensile-strength in both longitudinal and transverse directions and a low heat shrinkage is provided, while it has been considered that such properties could not be obtained in polyethylene terephthalate film.
Inventors
- 👤 Satoyuki Minami
- 👤 Kazuhiro Tanaka
- 👤 Takeshi Nishioka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 21:46
CPC Classifications
C; C08; C08J; C08J5/00; C08J5/18; B; B29; B29C; B29C55/00; B29C55/005; B29C55/02; B29C55/04; B29C55/06; B29C55/065; B29C55/10; B29C55/12; B29C55/14; B29C55/143; B29C55/16; G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/739; G11B5/73923; G11B5/73927; B29K; B29K2067/00; C08J2367/00; C08J2367/02; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/91; Y10T; Y10T428/00; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265; Y10T428/31504; Y10T428/31786
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
94 words
A process for producing a polyethylene terephthalate film which comprises extruding molten polyethylene terephthalate through a nozzle, cooling and solidifying the same to form a non-oriented sheet, stretching the sheet longitudinally in multiple stages to form a film having amorphous orientation factor of 0.6 to 1.0 and birefringence of 0.02 to 0.1, stretching the film transversely at a stretching ratio of 2.5 to 4.5, restretching the film biaxially at a stretching ratio of 1.5 to 2.5 in each direction and setting the film by heating to attain total-area stretching ratio of at least 27.
Claim 2
Dependent Claim
94 words
A process for producing a polyethylene terephthalate film which comprises extruding molten polyethylene terephthalate through a nozzle, cooling and solidifying the same to form a non-oriented sheet, stretching the sheet longitudinally in multiple stages to form a film having amorphous orientation factor of 0.6 to 1.0 and birefringence of 0.02 to 0.1, stretching the film transversely at a stretching ratio of 2.5 to 4.5, restretching the film biaxially at a stretching ratio of 1.5 to 2.5 in each direction and setting the film by heating to attain total-area stretching ratio of at least 27.
Claim 3
Dependent Claim
19 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the birefringence is 0.03 to 0.08.
Claim 4
Dependent Claim
20 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the multi-stage longitudinal stretching is two-stage stretching.
Claim 5
Dependent Claim
31 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the stretching temperature in the first stage in the multi-stage longitudinal stretching step is 110° to 150° C.
Claim 6
Dependent Claim
31 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the stretching temperature in the first stage in the multi-stage longitudinal stretching step is 115° to 135° C.
Claim 7
Dependent Claim
30 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the stretching ratio in the first stage in the multi-stage longitudinal stretching step is 1.3 to 3.0.
Claim 8
Dependent Claim
30 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the stretching ratio in the first stage in the multi-stage longitudinal stretching step is 1.5 to 2.5.
Claim 9
Dependent Claim
44 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the stretching temperature in and after the second stage in the multi-stage longitudinal stretching step is 85° to 120° C. and is lower than the stretching temperature in the first stage.
Claim 10
Dependent Claim
44 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the stretching temperature in and after the second stage in the multi-stage longitudinal stretching step is 95° to 115° C. and is lower than the stretching temperature in the first stage.
Claim 11
Dependent Claim
32 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the stretching ratio in and after the second stage in the multi-stage longitudinal stretching step is 2.0 to 4.0.
Claim 12
Dependent Claim
32 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the stretching ratio in and after the second stage in the multi-stage longitudinal stretching step is 2.0 to 3.0.
Claim 13
Dependent Claim
21 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the transverse stretching ratio is 2.6 to 4.5.
Claim 14
Dependent Claim
38 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the transverse stretching temperature is in the range from a point 5° C. higher than the second-order transition temperature of polyethylene terephthalate to 150° C.
Claim 15
Dependent Claim
38 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the transverse stretching temperature is in the range from the point 10° C. higher than the second-order transition temperature of polyethylene terephthalate to 130° C.
Claim 16
Dependent Claim
23 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the restretching is a longitudinal and transverse successive biaxial stretching.
Claim 17
Dependent Claim
23 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the restretching is a longitudinal and transverse simultaneous biaxial stretching.
Claim 18
Dependent Claim
65 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the stretching ratios in longitudinal and transverse directions in the restretching step are 1.5 to 2.5 each and the stretching temperature is in the range from the point 10° C. higher than the second-order transition temperature of polyethylene terephthalate to the point 40° C. lower than the melting point of polyethylene terephthalate.
Claim 19
Dependent Claim
54 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the stretching ratios in longitudinal and transverse directions in the restretching step are 1.5 to 2.3 and the stretching temperature is in the range from the point 15° C. higher than the second-order transition temperature of polyethylene terephthalate to 170° C.
Claim 20
Dependent Claim
21 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the total-area stretching ratio is at least 28.
Claim 21
Dependent Claim
21 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the total-area stretching ratio is at least 30.
Claim 22
Dependent Claim
44 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the heat-setting temperature is in the range from the point 50° C. higher than the second-order transition temperature to the point 10° C. lower than the melting point of polyethylene terephthalate.
Claim 23
Dependent Claim
51 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the heat-setting temperature is 10° C. higher than the restretching temperature and in the range from the point 80° C. higher than the second-order transition temperature to the point 20° C. lower than the melting point of polyethylene.
Claim 24
Dependent Claim
21 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the heat setting is carried out under tension.
Claim 25
Dependent Claim
21 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the heat setting is carried out under relaxation.
Claim 26
Dependent Claim
21 words
A process for producing a polyethylene terephthalate film according to claim 1 wherein the polyethylene terephthalate is an ethylene terephthalate homopolymer.
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) | 1989-05-05 | 1989-11-04 | 1990-05-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-05-05 | 1993-11-04 | 1994-05-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-05-05 | 1997-11-04 | 1998-05-06 | $7700.00 | Window Closed / Lapsed |