US4539260A
Expired / Lapsed
US
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Magnetic recording material
Assignee: Toray Industries Inc
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Filing: 1983-08-26
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Granted: 1985-09-03
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Expires: 2003-08-26
Abstract
Abstract A magnetic recording material which comprises a film of a polyester and a magnetic layer formed on at least one side of said film, said polyester containing more than 85 mol % of the repeating unit represented by the formula below and having an intrinsic viscosity of 0.3 to 1.4, and said film of said polyester having a refractive index ratio of 0.935 to 0.975 in the thickness direction and a density index of 0.02 to 0.08. <IMAGE> (where X is a halogen atom selected from fluorine, chlorine, and bromine, or an alkyl group of carbon number 1 to 3; and l and m are an integer of 1 to 2, p is an integer of 2 to 6, and q is an integer of 2 to 4.) Although the magnetic recording material is extremely thin, it exhibits outstanding running performance and electromagnetic conversion characteristics. It makes it possible to miniaturize the magnetic tape cassette and extend the recording time. It is useful for long-time video tape and portable 8-mm video tape.
Inventors
- 👤 Koichi Abe
- 👤 Kenichi Kawakami
- 👤 Toshiya Yoshii
- 👤 Toshihide Inoue
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 15:37
CPC Classifications
C; C08; C08J; C08J5/00; C08J5/18; C08G; C08G63/00; C08G63/68; C08G63/682; G; G11; G11B; G11B5/00; G11B5/62; G11B5/73; G11B5/739; G11B5/73923; G11B5/73927; C08J2367/00; C08J2367/02; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265; Y10T428/266; Y10T428/31504; Y10T428/31786
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
108 words
A magnetic recording material which comprises a film of a polyester and a magnetic layer formed on at least one side of said film, said polyester comprising more than 85 mol % of a main repeating unit represented by the formula: ##STR4## where X is a halogen atom selected from the group consisting of fluorine, chlorine and bormine; p is an integer of 2 to 6, and q is an integer of 2 to 4, and having an intrinsic viscosity of 0.3 to 1.4, and said film having a refractive index ratio of 0.935 to 0.975 in the thickness direction and a density index of 0.02 to 0.08.
Claim 2
Dependent Claim
108 words
A magnetic recording material which comprises a film of a polyester and a magnetic layer formed on at least one side of said film, said polyester comprising more than 85 mol % of a main repeating unit represented by the formula: ##STR4## where X is a halogen atom selected from the group consisting of fluorine, chlorine and bormine; p is an integer of 2 to 6, and q is an integer of 2 to 4, and having an intrinsic viscosity of 0.3 to 1.4, and said film having a refractive index ratio of 0.935 to 0.975 in the thickness direction and a density index of 0.02 to 0.08.
Claim 3
Dependent Claim
21 words
A magnetic recording material of claim 1, wherein the polyester comprises more than 90 mol % of the main repeating unit.
Claim 4
Dependent Claim
21 words
A magnetic recording material of claim 1, wherein the polyester comprises more than 95 mol % of the main repeating unit.
Claim 5
Dependent Claim
13 words
A magnetic recording material of claim 1, wherein p and are both 2.
Claim 6
Dependent Claim
11 words
A magnetic recording material of claim 1, wherein X is chlorine.
Claim 7
Dependent Claim
14 words
A magnetic recording material of claim 1, wherein the main repeating unit is ethylene-α,β-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylate.
Claim 8
Dependent Claim
13 words
A magnetic recording material of claim 1, wherein the polyester substantially comprises polyethylene-α,β-bis(2-chlorophenoxy)ethane-4,4'-dicarboxylate.
Claim 9
Dependent Claim
18 words
A magnetic recording material of claim 1, wherein the polyester has an intrinsic viscosity of 0.3 to 1.0.
Claim 10
Dependent Claim
24 words
A magnetic recording material of claim 1, wherein said base film has a refractive index ratio of 0.940 to 0.970 in the thickness direction.
Claim 11
Dependent Claim
19 words
A magnetic recording material of claim 1, wherein said base film has a density index of 0.02 to 0.05.
Claim 12
Dependent Claim
30 words
A magnetic recording material of claim 1, wherein the base film has a refractive index of 1.520 to 1.565 in the thickness direction and a density of 1.45 to 1.49.
Claim 13
Dependent Claim
30 words
A magnetic recording material of claim 1, wherein the base film has a refractive index of 1.530 to 1.560 in the thickness direction and a density of 1.46 to 1.48.
Claim 14
Dependent Claim
40 words
A magnetic recording material of claim 1, wherein the base film has a Young's modulus of 550 to 2000 kg/mm 2 in at least one direction and a heat shrinkage of 0 to 4% at 150° C. in said direction.
Claim 15
Dependent Claim
62 words
A magnetic recording material of claim 1, wherein the base film has a sum of the refractive indices in length and width directions is 3.305 to 3.420, and a difference of the refractive indices between length and width directions is -0.15 to 0.15, and a sum of the Young's moduli in length and width directions is 1500 to 2800 kg/mm 2 .
Claim 16
Dependent Claim
19 words
A magnetic recording material of claim 1, wherein the thickness of the base film is 2 to 12 μm.
Claim 17
Dependent Claim
19 words
A magnetic recording material of claim 1, wherein the magnetic layer has a thickness of 0.05 to 5 μm.
Claim 18
Dependent Claim
20 words
A magnetic recording material of claim 1, wherein the magnetic layer is a thin film consisting essentially of ferromagnetic metal.
Claim 19
Dependent Claim
50 words
A magnetic recording material of claim 17, wherein the ferromagnetic metal of the magnetic layer is a member selected from the group consisting of γ-Fe 2 O 3 , Fe 3 O 4 , Co-doped iron oxide, Fe, Co, Ni, Mn and an alloy containing at least one of them.
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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) | 1988-09-02 | 1989-03-04 | 1989-09-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-09-02 | 1993-03-04 | 1993-09-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-09-02 | 1997-03-04 | 1997-09-03 | $7700.00 | Window Closed / Lapsed |