Patent US5568466A successfully refreshed from Google Patents.
US5568466A
Expired / Lapsed
US
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Magneto-optical disc
Assignee: TDK Corp
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Filing: 1995-07-17
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Granted: 1996-10-22
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Expires: 2015-07-17
Abstract
Abstract A magneto-optical disc includes a recording layer (4) and a protective film (7) of radiation-cured resin on a substrate (2). Information is written in the recording layer with the aid of a magnetic head in sliding contact with the disc. In a first form, when the protective film is subject to a micro-vibration scratch test by setting the disc in a thin film scratch tester equipped with a diamond indentor having a radius of curvature R of up to 50 μm, the relationship: 0.8≦L/R 2 ≦2.7 is met wherein L is the critical load (N.m) under which the thin film is scratched. In a second form, the protective film has a dynamic modulus of 5.0×10 9 to 4.0×10 10 dyn/cm 2 at 100° C. The disc is highly durable.
Inventors
- 👤 Tsuyoshi Komaki
- 👤 Hiroyuki Endo
- 👤 Hideki Hirata
- 👤 Isamu Kuribayashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 16:23
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10582; G11B11/10586; G11B11/10584
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
103 words
In a magneto-optical disc comprising on a substrate a recording layer and a protective film of radiation-cured resin, wherein information is written in the recording layer with the aid of a magnetic head in sliding contact with the protective film, the improvement wherein in a micro-vibration scratch test made on the protective film by setting the disc in a thin film scratch tester equipped with a diamond indentor having a radius of curvature R (μm) of up to 50 μm, the protective film satisfies the relationship: 0.8≦L/R 2 ≦2.7 wherein L is the critical load (N.m) under which the thin film is scratched.
Claim 2
Dependent Claim
103 words
In a magneto-optical disc comprising on a substrate a recording layer and a protective film of radiation-cured resin, wherein information is written in the recording layer with the aid of a magnetic head in sliding contact with the protective film, the improvement wherein in a micro-vibration scratch test made on the protective film by setting the disc in a thin film scratch tester equipped with a diamond indentor having a radius of curvature R (μm) of up to 50 μm, the protective film satisfies the relationship: 0.8≦L/R 2 ≦2.7 wherein L is the critical load (N.m) under which the thin film is scratched.
Claim 3
Dependent Claim
64 words
In a magneto-optical disc comprising on a substrate a recording layer and a protective film of radiation-cured resin, wherein information is written in the recording layer with the aid of a magnetic head in sliding contact with the protective film, the improvement wherein said protective film of radiation-cured resin has a dynamic modulus of 5.0×10 9 to 4.0×10 10 dyn/cm 2 at 100° C.
Claim 4
Dependent Claim
64 words
In a magneto-optical disc comprising on a substrate a recording layer and a protective film of radiation-cured resin, wherein information is written in the recording layer with the aid of a magnetic head in sliding contact with the protective film, the improvement wherein said protective film of radiation-cured resin has a dynamic modulus of 5.0×10 9 to 4.0×10 10 dyn/cm 2 at 100° C.
Claim 5
Dependent Claim
28 words
The magneto-optical disc of claim 2 wherein said protective film of radiation-cured resin has a dynamic modulus of 2.5×10 9 to 3.0×10 10 dyn/cm 2 at 150° C.
Claim 6
Dependent Claim
21 words
The magneto-optical disc of claim 2 wherein said protective film of radiation-cured resin has a maximum tanδ of up to 0.2.
Claim 7
Dependent Claim
33 words
The magneto-optical disc of claim 1 wherein said protective film of radiation-cured resin is obtained by radiation curing a polymerizable composition comprising 40 to 90% by weight of a trifunctional or polyfunctional monomer.
Claim 8
Dependent Claim
15 words
The magneto-optical disc of claim 1 further comprising a lubricating layer on said protective film.
Claim 9
Dependent Claim
21 words
The magneto-optical disc of claim 1 wherein said magnetic head includes a slider having a dynamic hardness of 5 to 40.
Claim 10
Dependent Claim
21 words
The magneto-optical disk of claim 3, wherein said protective film of radiation-cured resin has a maximum tanδ of up to 0.2.
Claim 11
Dependent Claim
33 words
The magneto-optical disk of claim 2, wherein said protective film of radiation-cured resin is obtained by radiation curing a polymerizable composition comprising 40 to 90% by weight of a trifunctional or polyfunctional monomer.
Claim 12
Dependent Claim
15 words
The magneto-optical disk of claim 2, further comprising a lubricating layer on said protective film.
Claim 13
Dependent Claim
21 words
The magneto-optical disk of claim 2, wherein said magnetic head includes a slider having a dynamic hardness of 5 to 40.
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