US4639389A
Expired / Lapsed
US
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Magnetic recording medium
Assignee: TDK Corp
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Filing: 1984-12-12
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Granted: 1987-01-27
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Expires: 2004-12-12
Abstract
Abstract A magnetic recording medium comprising a plastic base film, a magnetic layer formed on one side of the base film and a backing layer formed on the other side of the base film, characterized in that said magnetic layer has a surface roughness of at most 0.08 μm, and said backing layer is composed essentially of first particles of an inorganic pigment having an average particle size of from 0.04 to 0.5 μm and a Mohs hardness of from 2 to 4 and second particles of an inorganic pigment having an average particles size of from 0.04 to 0.5 μm and a Mohs hardness of from 5 to 7, dispersed in a thermoset or radiation-cured binder.
Inventors
- 👤 Masaharu Nishimatsu
- 👤 Toshiaki Ide
- 👤 Hiroyuki Arioka
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 15:25
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/708; G11B5/7085; G11B5/73; G11B5/735; G11B5/7356; G11B5/7358; G11B5/739; G11B5/73923; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24355; Y10T428/24372; Y10T428/24405; Y10T428/25; Y10T428/31504; Y10T428/31551; Y10T428/31609; Y10T428/31855; Y10T428/31935; Y10T428/31938
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
151 words
A magnetic recording medium comprising a plastic base film, a magnetic layer formed on one side of the base film and a backing layer formed on the other side of the base film, characterized in that said magnetic layer has a surface roughness of at most 0.08 μm, and said backing layer having a surface roughness of from 0.05 to 0.6 μm and is composed essentially of first particles of an inorganic pigment having an average particle size of from 0.02 to 0.5 μm and a Mohs hardness of from 2 to 4 and second particles of an inorganic pigment having an average particle size of from 0.04 to 0.5 μm and a Mohs hardness of from 5 to 7 present in a weight ratio of 1:9 to 5:5, dispersed in a thermoset or radiation-cured binder the ratio of the total of said particles to said binder being 4:1 to 1:1.
Claim 2
Dependent Claim
151 words
A magnetic recording medium comprising a plastic base film, a magnetic layer formed on one side of the base film and a backing layer formed on the other side of the base film, characterized in that said magnetic layer has a surface roughness of at most 0.08 μm, and said backing layer having a surface roughness of from 0.05 to 0.6 μm and is composed essentially of first particles of an inorganic pigment having an average particle size of from 0.02 to 0.5 μm and a Mohs hardness of from 2 to 4 and second particles of an inorganic pigment having an average particle size of from 0.04 to 0.5 μm and a Mohs hardness of from 5 to 7 present in a weight ratio of 1:9 to 5:5, dispersed in a thermoset or radiation-cured binder the ratio of the total of said particles to said binder being 4:1 to 1:1.
Claim 3
Dependent Claim
21 words
The magnetic recording medium according to claim 1, wherein the magnetic layer has a coercive force of at least 1,000 Oe.
Claim 4
Dependent Claim
29 words
The magnetic recording medium according to claim 1, wherein the first particles are selected from the group consisting of CaCO 3 , ZnO, MgCO 3 and ZnCO 3 .
Claim 5
Dependent Claim
42 words
The magnetic recording medium according to claim 1, wherein the second particles are selected from the group consisting of TiO 2 , α-Fe 2 O 3 , Fe 3 O 4 , MgO, SiO 2 , SnO 2 and ZrO 2 .
Claim 6
Dependent Claim
42 words
The magnetic recording medium according to claim 2, wherein the second particles are selected from the group consisting of TiO 2 , α-Fe 2 O 3 , Fe 3 O 4 , MgO, SiO 2 , SnO 2 and ZrO 2 .
Claim 7
Dependent Claim
43 words
The magnetic recording medium according to claim 1, wherein the thermoset binder is made of a thermosetting resin composition comprising nitrocellulose, a polyurethane prepolymer, a vinyl chloride-vinyl acetate copolymer, a vinyl chloride-vinyl acetate-vinyl alcohol copolymer, a vinyl chloride-vinyl alcohol copolymer and a polyisocyanate.
Claim 8
Dependent Claim
31 words
The magnetic recording medium according to claim 1, wherein the thermoset binder is made of a thermosetting resin composition comprising a polyurethane prepolymer, a vinyl chloride-vinyl acetate copolymer and a polyisocyanate.
Claim 9
Dependent Claim
26 words
The magnetic recording medium according to claim 1, wherein the radiation-cured binder is made of a radiation curable resin having acrylic, maleic or allyl-type double bonds.
Claim 10
Dependent Claim
24 words
The magnetic recording medium according to claim 1, wherein the magnetic layer is composed essentially of ferromagnetic alloy powder dispersed in a resin binder.
Claim 11
Dependent Claim
18 words
The magnetic recording medium according to claim 1, wherein the magnetic layer is a thin ferromagnetic metal layer.
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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) | 1990-01-26 | 1990-07-28 | 1991-01-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-01-26 | 1994-07-28 | 1995-01-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-01-26 | 1998-07-28 | 1999-01-27 | $7700.00 | Window Closed / Lapsed |