US4198458A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Laminate polyester films
Assignee: Teijin Ltd
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Filing: 1975-07-10
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Granted: 1980-04-15
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Expires: 1995-07-10
Abstract
Abstract A stretch-oriented laminate polyester film consisting of two or three layers of polyester films; both polyester film A and polyester film B which form the external layers of the laminate film are composed of a polyester having an intrinsic viscosity of 0.35 to 1.0, wherein the intrinsic viscosity of a polyester forming the polyester film B is 0.02 to 0.5 greater than that of a polyester forming the polyester film A. The laminate film is curled in the widthwise direction with the polyester film B located inwardly of the curl. This film can be used for various applications, especially as a measuring tape, an adhesive tape and a base of a photographic film. As a preferred embodiment, a laminate polyester magnetic tape with reduced drop-out occurrence, comprising the stretch-oriented laminate film and a magnetic layer coated on one external layer thereof, the polyester film A forming one external layer of the laminate film having incorporated therein a finely-divided inert compound so that its coefficient of static friction becomes not more than 0.80, and the polyester film B forming the other external layer of the laminate film being a film having a coefficient of static friction greater than that of the polyester film A by at least 0.05 and a smoother surface, with the magnetic layer being coated on the surface of the polyester film B is disclosed.
Inventors
- 👤 Yukio Mitsuishi
- 👤 Shigeru Shiozaki
- 👤 Hitoshi Murakami
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:59
CPC Classifications
G; G03; G03C; G03C1/00; G03C1/76; G03C1/795; G03C1/7954; B; B32; B32B; B32B27/00; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/716; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10S428/91; Y10T; Y10T428/00; Y10T428/24; Y10T428/24942; Y10T428/25; Y10T428/26; Y10T428/269; Y10T428/31; Y10T428/31504; Y10T428/31786
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
132 words
A magnetic tape comprising a biaxially-stretched and heat-set polyester laminate having: (A) an extruded first polyester film forming a first layer of the laminate, having an intrinsic viscosity of 0.35 to 1.0, and containing a finely-divided inert compound so that the coefficient of static friction is not greater than 0.80; (B) a co-extruded second polyester film containing no finely-divided inert compound and forming a second layer of the laminate, having an intrinsic viscosity greater than that of film (A) by 0.02 to 0.5, and having a coefficient of static friction greater than that of film (A) by at least 0.05; and (C) a magnetic layer coated on the external surface of layer (B), the magnetic tape being curled in th widthwise direction and layer (B) being the inside layer of the curl.
Claim 2
Dependent Claim
132 words
A magnetic tape comprising a biaxially-stretched and heat-set polyester laminate having: (A) an extruded first polyester film forming a first layer of the laminate, having an intrinsic viscosity of 0.35 to 1.0, and containing a finely-divided inert compound so that the coefficient of static friction is not greater than 0.80; (B) a co-extruded second polyester film containing no finely-divided inert compound and forming a second layer of the laminate, having an intrinsic viscosity greater than that of film (A) by 0.02 to 0.5, and having a coefficient of static friction greater than that of film (A) by at least 0.05; and (C) a magnetic layer coated on the external surface of layer (B), the magnetic tape being curled in th widthwise direction and layer (B) being the inside layer of the curl.
Claim 3
Dependent Claim
57 words
The magnetic tape of claim 1 wherein the inert compound is at least one member selected from the group consisting of MgO, ZnO, MgCO 3 , CaCO 3 , CaSO 4 , BaSO 4 , Al 2 O 3 , SiO 2 , TiO 2 , calcium terephthalate, barium terephthalate, zinc terephthalate, manganese terephthalate, and carbon black.
Claim 4
Dependent Claim
28 words
The magnetic tape of claim 1 wherein the amount of the inert compound added is from 0.01 to 40% by weight based on the weight of layer (A).
Claim 5
Dependent Claim
28 words
The magnetic tape of claim 3 wherein the amount of the inert compound added is from 0.05 to 5% by weight, based on the weight of layer (A).
Claim 6
Dependent Claim
28 words
The magnetic tape of claim 4 wherein the amount of the inert compound added is from 0.1 to 2% by weight, based on the weight of layer (A).
Claim 7
Dependent Claim
35 words
The magnetic tape of claim 1 wherein the particle diameter of the inert compound, expressed as the arithmetic mean of the maximum and minimum values of the diameter, is from about 0.1 to 10 microns.
Claim 8
Dependent Claim
26 words
The magnetic tape of claim 1 wherein the coefficient of static friction of layer (B) is greater than that of layer (A) by at least 0.2.
Claim 9
Dependent Claim
26 words
The magnetic tape of claim 7 wherein the coefficient of static friction of layer (B) is greater than that of layer (A) by at least 0.5.
Claim 10
Dependent Claim
18 words
The magnetic tape of claim 1 wherein the thickness of the laminate is from 1 to 200 microns.
Claim 11
Dependent Claim
18 words
The magnetic tape of claim 9 wherein the thickness of the laminate is from 6 to 50 microns.
Claim 12
Dependent Claim
30 words
The magnetic tape of claim 1 wherein the proportion of the thickness of layer A is from 5 to 50% by weight, of the thickness of the base laminate film.
Claim 13
Dependent Claim
28 words
The magnetic tape of claim 1 wherein at least one of layers (A) and (B) is a layer of a polymer blend consisting of polyethylene terephthalate and polyethylene-2,6-naphthalate.
Claim 14
Dependent Claim
23 words
The magnetic tape of claim 35 wherein the proportion of the polyethylene-2,6-naphthalate in the polymer blend is from 0.1 to 49.0% by weight.
Claim 15
Dependent Claim
13 words
The magnetic tape of claim 1 wherein the inert compound is carbon black.
Claim 16
Dependent Claim
19 words
The magnetic tape of claim 1 wherein layer (A) has a surface resistivity of less than 10 12 ohms.
Claim 17
Dependent Claim
20 words
The magnetic tape of claim 14 wherein the amount of the carbon black is from 10 to 40% by weight.
Claim 18
Dependent Claim
20 words
The magnetic tape of claim 16 wherein the amount of the carbon black is from 15 to 25% by weight.
Claim 19
Dependent Claim
21 words
The magnetic tape of claim 9 wherein the intrinsic viscosity for the polyester constituting the layers ranges from 0.4 to 0.9.
Claim 20
Dependent Claim
25 words
The magnetic tape of claim 18 wherein the difference in intrinsic viscosity between that of film (A) and film (B) is from 0.03 to 0.2.
Claim 21
Dependent Claim
25 words
The magnetic tape of claim 19 wherein the difference in intrinsic viscosity between that of film (A) and film (B) is from 0.04 to 0.1.
Claim 22
Dependent Claim
22 words
The magnetic tape of claim 1 wherein the laminate film has a longitudinal F-5 value of at least 12.0 kg/mm 2 .
Claim 23
Dependent Claim
21 words
The magnetic tape of claim 1 wherein the magnetic layer consists essentially of a circular γ-type ferric oxide and a binder.
Claim 24
Dependent Claim
41 words
The film of claim 1 wherein the laminate is stretched longitudinally at a ratio of 3.5 to 6.0 and transversely at a ratio of 1.5 to 4.0, with the longitudinal stretch ratio being greater than the transverse by at least 0.3.
Claim 25
Dependent Claim
39 words
The film of claim 23 wherein the laminate is stretched longitudinally at a ratio of 4.0 to 5.0 and transversely at a ratio of 2.5 to 3.5, the longitudinal ratio being greater than the transverse by at least 0.7.
Claim 26
Dependent Claim
21 words
The film of claim 24 wherein the longitudinal stretch ratio is greater than the transverse stretch ratio by at least 1.0.
Claim 27
Dependent Claim
41 words
The film of claim 1 wherein the laminate is stretched longitudinally at a ratio of 3.5 to 6.0 and transversely at a ratio of 1.5 to 4.0, with the longitudinal stretch ratio being greater than the transverse by at least 0.3.
Claim 28
Dependent Claim
39 words
The film of claim 26 wherein the laminate is stretched longitudinally at a ratio of 4.0 to 5.0 and transversely at a ratio of 2.5 to 3.5, the longitudinal ratio being greater than the transverse by at least 0.7.
Claim 29
Dependent Claim
21 words
The film of claim 27 wherein the longitudinal stretch ratio is greater than the transverse stretch ratio by at least 1.0.
Claim 30
Dependent Claim
19 words
The magnetic tape of claim 1 having additionally (D) a third polyester film interposed between films (A) and (B).
Claim 31
Dependent Claim
32 words
The magnetic tape of claim 29 wherein the polyester constituting the layers (A), (B), and (D) is a homopolyester selected from the group consisting of polyethylene terephthalate, polyethylene-2,6-naphthalate, polytetramethylene terephthalate, and polytetramethylene-2,6-naphthalate.
Claim 32
Dependent Claim
12 words
The film of claim 29 wherein pigments are incorporated in layer (C).
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-04-15 | 1983-10-15 | 1984-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-04-15 | 1987-10-15 | 1988-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-04-15 | 1991-10-15 | 1992-04-15 | $7700.00 | Window Closed / Lapsed |