US3959553A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic discs having metal support and a non-magnetic layer
Assignee: BASF SE
•
Filing: 1973-11-09
•
Granted: 1976-05-25
•
Expires: 1993-11-09
Abstract
Abstract The invention relates to magnetic discs in which first a non-magnetic intermediate layer and then the magnetic coating are applied by conventional methods to an aluminum disc. The intermediate layer applied to the non-magnetic metallic carrier disc is a hard non-magnetic coating which can be polished and which consists of a dispersion of a pulverulent mixture of finely divided inorganic non-magnetic pigments having a Mohs' hardness of at least 7 in a binder which can be cured and which provides firm cohesion of the pigment particles and good adhesion thereof to the non-magnetic base disc, the pigment mixture containing at least 3 percent by weight of corundum powder having a particle size of from about 1 to 20μu. Magnetic discs with very thin magnetic coatings which possess good magnetic and mechanical properties and whose thickness varies only minimally are thus produced in a simple manner.
Inventors
- 👤 Job Werner Hartmann
- 👤 Werner Ostertag
- 👤 Rudolf Sand
- 👤 Dieter Schaefer
- 👤 Hans Joerg Hartmann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 02:14
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/708; G11B5/7085; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257; Y10T428/29; Y10T428/2982; Y10T428/31504; Y10T428/31511; Y10T428/31529
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
179 words
Magnetic discs manufactured by coating a non-magnetic metallic base disc with a dispersion of a finely divided magnetic pigment in a solution of a binder in an organic solvent and converting the coating into a solid hard magnetic coating of predetermined hardness by drying and curing and subsequently grinding and/or polishing the magnetic coating, wherein the non-magnetic metallic base disc has first been coated with a hard and polishable non-magnetic intermediate layer having a thickness of from 2 to 25 μ of a pulverulent mixture of finely divided inorganic non-magnetic pigments having a Mohs' hardness of at least 7, said mixture containing at least 3 percent by weight, based on the pigment mixture, of corundum powder having a particle size of from about 1 to 20 μ, dispersed in a curable binder, said intermediate layer containing about 50 to 75 percent by weight of the mixture of finely divided non-magnetic pigments, based on the sum of the amounts of pigment and binder which provides firm cohesion of the pigment particles and good adhesion thereof to the non-magnetic base disc.
Claim 2
Dependent Claim
179 words
Magnetic discs manufactured by coating a non-magnetic metallic base disc with a dispersion of a finely divided magnetic pigment in a solution of a binder in an organic solvent and converting the coating into a solid hard magnetic coating of predetermined hardness by drying and curing and subsequently grinding and/or polishing the magnetic coating, wherein the non-magnetic metallic base disc has first been coated with a hard and polishable non-magnetic intermediate layer having a thickness of from 2 to 25 μ of a pulverulent mixture of finely divided inorganic non-magnetic pigments having a Mohs' hardness of at least 7, said mixture containing at least 3 percent by weight, based on the pigment mixture, of corundum powder having a particle size of from about 1 to 20 μ, dispersed in a curable binder, said intermediate layer containing about 50 to 75 percent by weight of the mixture of finely divided non-magnetic pigments, based on the sum of the amounts of pigment and binder which provides firm cohesion of the pigment particles and good adhesion thereof to the non-magnetic base disc.
Claim 3
Dependent Claim
29 words
A disc as claimed in claim 1, wherein the pulverulent mixture of finely divided inorganic pigments contains at least 20 percent by weight of cerium dioxide, CeO 2 .
Claim 4
Dependent Claim
54 words
A disc as claimed in claim 1, wherein the pulverulent mixture of finely divided inorganic pigments contains at least 40 percent by weight of a cerium powder which contains at least 45 percent by weight of cerium dioxide, CeO 2 , The remainder of the cerium powder consisting essentially of oxides of rare earths.
Claim 5
Dependent Claim
18 words
A disc as claimed in claim 1, wherein the intermediate layer is about 1 eo 10 μ thick.
Claim 6
Dependent Claim
21 words
A disc as claimed in claim 1, wherein the curable binder of the intermediate layer consists predominantly of an epoxy resin.
Claim 7
Dependent Claim
65 words
A disc as claimed in claim 1, wherein the pulverulent mixture of finely divided inorganic pigments contains from 5 to 12 percent by weight of corundum powder and 88 to 95 percent Cerium dioxide, CeO 2 , or Cerium powder which consists of at least 45 percent by weight of CeO 2 the remainder of the cerium powder consisting essentially of oxides or rare earths.
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) | 1979-05-25 | 1979-11-24 | 1980-05-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-05-25 | 1983-11-24 | 1984-05-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-05-25 | 1987-11-24 | 1988-05-25 | $7700.00 | Window Closed / Lapsed |