US4100326A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for treating a magnetic recording medium
Assignee: Sony Corp
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Filing: 1975-07-11
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Granted: 1978-07-11
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Expires: 1995-07-11
Abstract
Abstract A method of preparing a magnetic recording medium, the surface of which has a very smooth magnetic layer. Magnetic paint is coated on a non-magnetic base, which is then passed between calender rolls which comprise a polyurethane roll and a steel roll heated between approximately 40° C. and 200° C. The hardness of the polyurethane roll is greater than approximately 70° in Shore D, and the pressure between the rolls is between approximately 50 Kg/cm and 500 Kg/cm.
Inventors
- 👤 Masashi Somezawa
- 👤 Shigetaka Higuchi
- 👤 Tatsuo Shimizu
- 👤 Isao Ishibashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 02:31
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/84
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
137 words
A dry-calendering method of treating a magnetic tape formed of a flexible base of non-magnetic material supporting a magnetic layer containing finely-divided magnetic particles dispersed in a flexible binder to have low surface roughness and a high density of magnetic particles comprising the steps of passing said tape, in the absence of an introduced lubricant, between a metal roll and an elastic roll having a polyurethane cylindrical surface with a hardness of no less than approximately 70° measured in Shore D, the temperature of said metal roll being in the range of approximately 40° C. to approximately 200° C. at the cylindrical surface thereof, and the pressure between said rolls being in the range from approximately 50 Kg/cm to approximately 500 Kg/cm, the metal roll contacting said magnetic layer and the elastic roll contacting said flexible base.
Claim 2
Dependent Claim
137 words
A dry-calendering method of treating a magnetic tape formed of a flexible base of non-magnetic material supporting a magnetic layer containing finely-divided magnetic particles dispersed in a flexible binder to have low surface roughness and a high density of magnetic particles comprising the steps of passing said tape, in the absence of an introduced lubricant, between a metal roll and an elastic roll having a polyurethane cylindrical surface with a hardness of no less than approximately 70° measured in Shore D, the temperature of said metal roll being in the range of approximately 40° C. to approximately 200° C. at the cylindrical surface thereof, and the pressure between said rolls being in the range from approximately 50 Kg/cm to approximately 500 Kg/cm, the metal roll contacting said magnetic layer and the elastic roll contacting said flexible base.
Claim 3
Dependent Claim
26 words
The method of claim 1 in which the hardness of said cylindrical surface of said polyurethane is between approximately 70° and 85° measured in Shore D.
Claim 4
Dependent Claim
24 words
The method of claim 2 in which the cylindrical surface of said polyurethane roll has a hardness of approximately 85° measured in Shore D.
Claim 5
Dependent Claim
22 words
The method of claim 1 in which the temperature of the cylindrical surface of said polyurethane is less than approximately 100° C.
Claim 6
Dependent Claim
31 words
The method of claim 4 comprising, in addition, blowing cooling air across the cylindrical surface of said polyurethane to maintain the temperature of said cylindrical surface less than approximately 100° C.
Claim 7
Dependent Claim
23 words
The method of claim 1 in which the pressure between said rolls is in the range between approximately 150 Kg/cm and 300 Kg/cm.
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) | 1981-07-10 | 1982-01-09 | 1982-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-07-10 | 1986-01-09 | 1986-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-07-10 | 1990-01-09 | 1990-07-11 | $7700.00 | Window Closed / Lapsed |