US4720412A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polyester base film for magnetic recording media
Assignee: Teijin Ltd
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Filing: 1986-04-11
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Granted: 1988-01-19
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Expires: 2006-04-11
Abstract
Abstract A biaxially stretched polyester base film having many fine protrusions on its surface, characterized by having the following properties: (a) in a distribution curve representing the relation between the number of protrusions (y/mm 2 ) and the height of protrusions (x in μm) on the surface of said film which are measured in a region having at least 20 protrusions/mm 2 , that part of the distribution curve at which the protrusion height (x) is larger than its peak value crosses the line of log 10 y=-18x+3.7, (b) when the number of protrusions (y) on the film surface is at least 20/mm 2 , no protrusion exists which has a height (x) of at least 0.13 μm, (c) said film has a surface roughness (Ra) of not more than 0.012 μm, (d) said film has a Young's modulus in the longitudinal direction of at least 650 kg/mm 2 , and (e) when heat-treated at 70° C. for 1 hour under no load, said film has a heat shrinkage in the longitudinal direction of not more than 0.1%.
Inventors
- 👤 Hideo Katoh
- 👤 Hiroshi Tomita
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 21:22
CPC Classifications
C; C08; C08J; C08J5/00; C08J5/18; B; B29; B29C; B29C55/00; B29C55/02; B29C55/10; B29C55/12; C08K; C08K3/00; C08K3/18; C08K3/20; C08K3/22; C08K3/24; C08K3/26; C08K3/34; C08K3/36; G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/739; G11B5/73923; G11B5/73927; G11B5/73935; C08J2367/00; C08J2367/02; C08K2003/2237; C08K2003/2241; C08K2003/265; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24355; Y10T428/31504; Y10T428/31786
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
190 words
A biaxially stretched, single-layer polyester base film containing inert solid fine particles dispersed therein and having may fine protrusions on its surface, said film having the following properties: (a) in a distribution curve representing the relation between the number of protrusions (y/mm 2 ) and the height of protrusions (x in μm) on the surface of said film which are measured in a region having at least 20 protrusions/mm 2 , that part of the distribution curve at which the protrusion height (x) is larger than its peak value of the distribution curve crosses the line of log 10 y=-18x+3.7, (b) when the number of protrusions (y) on the film surface is at least 20/mm 2 , no protrusion exists which has a height (x) of at least 0.13 μm, (c) said film has a surface roughness (Ra) of not more than 0.012 μm, (d) said film has a Young's modulus in the longitudinal direction of at least 650 kg/mm 2 , and (e) when heat-treated at 70° C. for 1 hour under no load, said film has a heat shrinkage in the longitudinal direction of not more than 0.1%.
Claim 2
Dependent Claim
190 words
A biaxially stretched, single-layer polyester base film containing inert solid fine particles dispersed therein and having may fine protrusions on its surface, said film having the following properties: (a) in a distribution curve representing the relation between the number of protrusions (y/mm 2 ) and the height of protrusions (x in μm) on the surface of said film which are measured in a region having at least 20 protrusions/mm 2 , that part of the distribution curve at which the protrusion height (x) is larger than its peak value of the distribution curve crosses the line of log 10 y=-18x+3.7, (b) when the number of protrusions (y) on the film surface is at least 20/mm 2 , no protrusion exists which has a height (x) of at least 0.13 μm, (c) said film has a surface roughness (Ra) of not more than 0.012 μm, (d) said film has a Young's modulus in the longitudinal direction of at least 650 kg/mm 2 , and (e) when heat-treated at 70° C. for 1 hour under no load, said film has a heat shrinkage in the longitudinal direction of not more than 0.1%.
Claim 3
Dependent Claim
33 words
The film of claim 1 wherein when the number of protrusions, y, is at least 20/mm 2 , the film does not contain protrusions having a height (x) of at least 0.10 micrometer.
Claim 4
Dependent Claim
17 words
The film of claim 1 which has a surface roughenss (Ra) of not more than 0.010 micrometer.
Claim 5
Dependent Claim
16 words
The film of claim 3 which has a surface roughness (Ra) of 0.004 to 0.008 micrometer.
Claim 6
Dependent Claim
21 words
The film of claim 3 which has a Young's modulus in the longitudinal direction of at least 700 kg/mm 2 .
Claim 7
Dependent Claim
21 words
The film of claim 5 which has a Young's modulus in the longitudinal direction of at least 750 kg/mm 2 .
Claim 8
Dependent Claim
19 words
The film of claim 1 which has a heat shrinkage in the longitudinal direction of not more than 0.06%.
Claim 9
Dependent Claim
19 words
The film of claim 7 which has a heat shrinkage in the longitudinal direction of not more than 0.03%.
Claim 10
Dependent Claim
28 words
The film of claim 7 which has been stretched to 4.1 to 5.5 times in the longitudinal direction and to 3.0 to 3.8 times in the transverse direction.
Claim 11
Dependent Claim
11 words
The film of claim 1 wherein the polyester is polyethylene terephthalate.
Claim 12
Dependent Claim
22 words
The film of claim 1 wherein the inert solid fine particles are fine particles of silicon dioxide, titanium dioxide or calcium carbonate.
Claim 13
Dependent Claim
14 words
The film of claim 1 which has a magnetic recording layer on its surface.
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) | 1991-01-18 | 1991-07-20 | 1992-01-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-01-18 | 1995-07-20 | 1996-01-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-01-18 | 1999-07-20 | 2000-01-19 | $7700.00 | Window Closed / Lapsed |