US3995089A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording media
Assignee: BASF SE
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Filing: 1975-04-02
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Granted: 1976-11-30
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Expires: 1995-04-02
Abstract
Abstract A magnetic recording medium in the form of a card having a non-magnetic support with a magnetic coating on one side of the support and a backcoating on the opposite side of the support, which backcoating exhibits improved scratch resistance and adherence to the support and improved frictional characteristics and consists essentially of 20 to 50% by weight of a binder mixture containing 10 to 60% by weight of an elastomeric polyurethane and, incorporated in the binder mixture, a non-magnetic pulverulent mixture of 10 to 40% by weight of conductive carbon powder and 60 to 90% by weight of platelet-shaped and spherical particles.
Inventors
- 👤 Job Werner Hartmann
- 👤 Hans-Joerg Hartmann
- 👤 Dieter Mayer
- 👤 Peter Felleisen
- 👤 Ursula Klein
- 👤 Herbert Motz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 09:19
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/708; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/24; Y10T428/24355; Y10T428/24372; Y10T428/24413; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265; Y10T428/31504; Y10T428/31551; Y10T428/31609
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
165 words
A magnetic recording medium in card form comprising a flat non-magnetic support, a magnetic coating on one side of the support and a backcoating comprising polymeric binder, conductive particles and non-magnetic pigments on the opposite side of the support, wherein the said backcoating consists essentially of i. 20 to 50% by weight of a binder containing 10 to 60% by weight of an elastomeric flexible polyurethane substantially free of isocyanate groups, and ii. a non-magnetic pulverulent mixture of 10 to 40 parts by weight of conductive carbon powder (a), 40 to 90 parts by weight of an intimate mixture (b) of 20 to 45% by weight of kaolinite powder having platelet-shaped particles and 55 to 80% by weight of quartz powder having spherical particles, and optionally 5 to 40 parts by weight of corundum powder (c) having spherical particles the coefficient of friction (C m ) between the back surface of a card and the magnetized surface of an adjacent card being less than 0.50.
Claim 2
Dependent Claim
165 words
A magnetic recording medium in card form comprising a flat non-magnetic support, a magnetic coating on one side of the support and a backcoating comprising polymeric binder, conductive particles and non-magnetic pigments on the opposite side of the support, wherein the said backcoating consists essentially of i. 20 to 50% by weight of a binder containing 10 to 60% by weight of an elastomeric flexible polyurethane substantially free of isocyanate groups, and ii. a non-magnetic pulverulent mixture of 10 to 40 parts by weight of conductive carbon powder (a), 40 to 90 parts by weight of an intimate mixture (b) of 20 to 45% by weight of kaolinite powder having platelet-shaped particles and 55 to 80% by weight of quartz powder having spherical particles, and optionally 5 to 40 parts by weight of corundum powder (c) having spherical particles the coefficient of friction (C m ) between the back surface of a card and the magnetized surface of an adjacent card being less than 0.50.
Claim 3
Dependent Claim
38 words
A magnetic recording medium as set forth in claim 1 wherein the non-magnetic pulverulent mixture consists of 10 to 25 parts by weight of carbon black powder (a) and 75 to 90 parts by weight of mixture (b).
Claim 4
Dependent Claim
49 words
A magnetic recording medium as set forth in claim 1 wherein the non-magnetic pulverulent mixture consists of 10 to 40 parts by weight of conductive carbon powder (a), 40 to 85 parts by weight of mixture (b) and 5 to 40 parts by weight of corundum powder (c) .
Claim 5
Dependent Claim
23 words
A magnetic recording media as set forth in claim 1 in which said backcoating has a thickness of from 7 to 13 μ.
Claim 6
Dependent Claim
23 words
A magnetic recording media as set forth in claim 1 in which said backcoating has a thickness of from 9 to 11 μ.
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) | 1979-11-30 | 1980-05-31 | 1980-11-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-11-30 | 1984-05-31 | 1984-11-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-11-30 | 1988-05-31 | 1988-11-30 | $7700.00 | Window Closed / Lapsed |