Patent US4650708A successfully refreshed from Google Patents.
US4650708A
Expired / Lapsed
US
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Magnetic recording material and a method for producing the same
Assignee: Individual
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Filing: 1984-05-22
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Granted: 1987-03-17
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Expires: 2004-05-22
Abstract
Abstract In production of a magnetic recording material which accumulates information in magnetic substance packed in micro pores extending in the thickness direction of an anodic oxide surface layer formed on an aluminum foil by anodic oxidation and electrolylic deposition, ferromagnetic substance such as Fe--Co--Ni alloys is used for packing and the pore diameter is adjusted to a range from 40 to 100 nm in order to obtain highly improved magnetic characteristics which enable high density magnetic recording.
Inventors
- 👤 Toshiro Takahashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 17:46
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/84; G11B5/62; G11B5/73; G11B5/7368; G11B5/7369; G11B5/739; G11B5/73911; G11B5/73917; G11B5/73919; Y; Y10; Y10S; Y10S205/00; Y10S205/917; Y10S205/922; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/249921; Y10T428/249953; Y10T428/249955; Y10T428/249956; Y10T428/249975; Y10T428/249987; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
124 words
An improved magnetic recording material comprising a substrate containing a predominant amount of aluminum, an anodic oxide surface layer located in the surface section of said substrate and provided with a plurality of micro pores each of which extends in the thickness direction of said anodic oxide surface layer and has a diameter in a range of from 40 to 100 nm, the thickness of said anodic oxide surface layer being less than about 3.0 μm, a barrier layer located beneath said anodic oxide surface layer and having a thickness in a range of from 8 to 28 nm, and a ferromagnetic substance packed in said micro pores in said anodic oxide surface layer at a degree of packing of greater than about 41%.
Claim 2
Dependent Claim
124 words
An improved magnetic recording material comprising a substrate containing a predominant amount of aluminum, an anodic oxide surface layer located in the surface section of said substrate and provided with a plurality of micro pores each of which extends in the thickness direction of said anodic oxide surface layer and has a diameter in a range of from 40 to 100 nm, the thickness of said anodic oxide surface layer being less than about 3.0 μm, a barrier layer located beneath said anodic oxide surface layer and having a thickness in a range of from 8 to 28 nm, and a ferromagnetic substance packed in said micro pores in said anodic oxide surface layer at a degree of packing of greater than about 41%.
Claim 3
Dependent Claim
27 words
An improved magnetic recording material as claimed in claim 1 in which the diameter of said micro pores is in a range from 40 to 75 nm.
Claim 4
Dependent Claim
64 words
An improved magnetic recording material as claimed in claim 1 in which the ratio of cell diameter (Dc) with respect to pore diameter (Dp) is in a range from 1.4 to 2.7 for pore diameters in a range from 40 to 50 nm, said cell diameter (Dc) referring to the distance between center axes of adjacent micro pores in said anodic oxide surface layer.
Claim 5
Dependent Claim
68 words
An improved magnetic recording material as claimed in claim 1 in which the ratio of cell diameter (Dc) with respect to pore diameter (Dp) is in a range from 1.4 to {2.7-(1.2/50 nm) (Dp-50 nm)} for pore diameters in a range from 50 to 100 nm, said cell diameter (Dc) referring to the distance between the center axes of adjacent micro pores in said anodic oxide surface layer.
Claim 6
Dependent Claim
23 words
An improved magnetic recording material as claimed in claim 1 in which said ferromagnetic substance contains 50% by weight or more of Fe.
Claim 7
Dependent Claim
30 words
An improved magnetic recording material as claimed in claim 5 in which said ferromagnetic substance is chosen from a group consisting of Fe, Fe--Co alloys, Fe--Ni alloys and Fe--Co--Ni alloys.
Claim 8
Independent Claim
153 words
A method for producing an improved magnetic recording material comprising the steps of forming an anodic oxide surface layer having a thickness less than about 3.0 μm and a plurality of micro pores on a foil containing a predominant amount of aluminum by an anodic oxidation process whose condition is adjusted so that a barrier layer is concurrently formed beneath said anodic oxide surface layer; enlarging said micro pores by subjecting said foil to electrolysis in which said electrolysis is first advanced with a small constant electric current, the mode of electrolysis is then converted to one with a constant electric voltage when the electrolytic voltage has dwindled down to a level effective to produce a barrier layer having a thickness in the range of from 8 to 28 nm, and said electrolysis is ceased after an electric current has been established; and packing ferromagnetic substances into said micro pores by electrolytic deposition.
Claim 9
Independent Claim
153 words
A method for producing an improved magnetic recording material comprising the steps of forming an anodic oxide surface layer having a thickness less than about 3.0 μm and a plurality of micro pores on a foil containing a predominant amount of aluminum by an anodic oxidation process whose condition is adjusted so that a barrier layer is concurrently formed beneath said anodic oxide surface layer; enlarging said micro pores by subjecting said foil to electrolysis in which said electrolysis is first advanced with a small constant electric current, the mode of electrolysis is then converted to one with a constant electric voltage when the electrolytic voltage has dwindled down to a level effective to produce a barrier layer having a thickness in the range of from 8 to 28 nm, and said electrolysis is ceased after an electric current has been established; and packing ferromagnetic substances into said micro pores by electrolytic deposition.
Claim 10
Dependent Claim
53 words
A method as claimed in claim 7 in which the process condition of said anodic oxidation is adjusted so that the ratio of cell diameter (Dc) with respect to pore diameter (Dp) is in a range of from 1.4 to 2.7 for pore diameters in a range of from 40 to 50 nm.
Claim 11
Dependent Claim
56 words
A method as claimed in claim 7 in which the process condition of said anodic oxidation is adjusted so that the ratio of cell diameter (Dc) with respect to pore diameter (Dp) is in a range of from 1.4 to {2.7-(1.2/50 nm) (Dp-50 nm)} for pore diameters in a range of from 50 to 100 nm.
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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) | 1990-03-16 | 1990-09-15 | 1991-03-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-03-16 | 1994-09-15 | 1995-03-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-03-16 | 1998-09-15 | 1999-03-17 | $7700.00 | Window Closed / Lapsed |