US4547393A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for preparing a magnetic recording medium
Assignee: Fujifilm Holdings Corp
•
Filing: 1984-06-08
•
Granted: 1985-10-15
•
Expires: 2004-06-08
Abstract
Abstract The present invention relates to an improved method for preparing a magnetic recording method having excellent magnetic orientation comprising the steps of (1) dispersing ferromagnetic fine particles which are plate-shaped and which have an axis of magnetization perpendicular to the plates of the particles in a binder and (2) coating a magnetic coating layer on a non-magnetic support wherein the method comprises, after coating the magnetic coating layer and before drying it, subjecting the surface of the magnetic layer to a magnetic field from the direction perpendicular to the support to produce a magnetic orientation while contacting the surface of the magnetic layer with a flexible smoothening sheet.
Inventors
- 👤 Takamitsu Asai
- 👤 Tatsuji Kitamoto
- 👤 Goro Akashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 01:27
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/84; G11B5/842; G11B5/845; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/708; G11B5/7085
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
279 words
A method for preparing a magnetic recording medium comprising the steps of (1) dispersing in a binder ferromagnetic fine particles which are plate-shaped and which have an axis of easy magnetization perpendicular to the plate of the particles in a binder and (2) coating a magnetic coating layer on a non-magnetic support, wherein the method includes, after coating the magnetic coating layer and before drying it, subjecting the surface of the magnetic layer to a magnetic filed from the direction perpendicular to the support to produce a magnetic orientation while contacting the surface of the magnetic coating layer with a flexible smoothening sheet, and wherein the ferromagnetic fine particles are selected from the group consisting of AFe 12 O 19 , wherein A is at least one member selected from the group consisting of Ba, Sr, Pb and Ca; A'Fe 12-x M x O 19 , wherein A' is at least one member selected from the group consisting of In, 1/2Zn+1/2Ge, 1/2Zn+1/2Nb, 1/2Zn+1/2V, 1/2Co+1/2Ti and 1/2Co+1/2Ge and wherein x is greater than or equal to 1.0 and less than or equal to 2.2; group consisting of Ba, Sr, Ca and Pb and wherein M is at least one member selected from the group consisting of Zn, Ni, Cu, Fe and Mn; A'"Fe 12-2y Co y M" y O 19 wherein A'" is at least one member selected from the group consisting of Ba, Sr, Pb and Co and wherein M" is selected from at least one member of the group consisting of Ti, Ge, 1/2Ti+1/2Ge and wherein y is greater than or equal to 0.5 and less than or equal to 1.1; and a hexacrystal cobalt alloy and MnBi.
Claim 2
Independent Claim
279 words
A method for preparing a magnetic recording medium comprising the steps of (1) dispersing in a binder ferromagnetic fine particles which are plate-shaped and which have an axis of easy magnetization perpendicular to the plate of the particles in a binder and (2) coating a magnetic coating layer on a non-magnetic support, wherein the method includes, after coating the magnetic coating layer and before drying it, subjecting the surface of the magnetic layer to a magnetic filed from the direction perpendicular to the support to produce a magnetic orientation while contacting the surface of the magnetic coating layer with a flexible smoothening sheet, and wherein the ferromagnetic fine particles are selected from the group consisting of AFe 12 O 19 , wherein A is at least one member selected from the group consisting of Ba, Sr, Pb and Ca; A'Fe 12-x M x O 19 , wherein A' is at least one member selected from the group consisting of In, 1/2Zn+1/2Ge, 1/2Zn+1/2Nb, 1/2Zn+1/2V, 1/2Co+1/2Ti and 1/2Co+1/2Ge and wherein x is greater than or equal to 1.0 and less than or equal to 2.2; group consisting of Ba, Sr, Ca and Pb and wherein M is at least one member selected from the group consisting of Zn, Ni, Cu, Fe and Mn; A'"Fe 12-2y Co y M" y O 19 wherein A'" is at least one member selected from the group consisting of Ba, Sr, Pb and Co and wherein M" is selected from at least one member of the group consisting of Ti, Ge, 1/2Ti+1/2Ge and wherein y is greater than or equal to 0.5 and less than or equal to 1.1; and a hexacrystal cobalt alloy and MnBi.
Claim 3
Dependent Claim
24 words
A method for preparing a magnetic recording medium as in claim 1, wherein the flexible smoothing sheet is positioned vertical to the magnetic field.
Claim 4
Dependent Claim
27 words
A method for preparing a magnetic recording medium as in claim 1, wherein the ferromagnetic fine particles have a maximum length of 80 Å to 10 microns.
Claim 5
Dependent Claim
34 words
A method for preparing a magnetic recording medium as in claim 1, wherein the binder is selected from at least one member of the group consisting of thermoplastic resins, thermosetting resins and reactive resins.
Claim 6
Dependent Claim
44 words
A method for preparing a magnetic recording medium as in claim 4, wherein the thermoplastic resins have a softening point of not higher than 150° C., an average molecular weight of 10,000 to 200,000 and a degree of polymerization of about 400 to 500.
Claim 7
Dependent Claim
33 words
A method for preparing a magnetic recording medium as in claim 4, wherein the thermosetting resins and reactive resins have a molecular weight of not higher than 200,000 in the coating solution state.
Claim 8
Dependent Claim
28 words
A method for preparing a magnetic recording medium as in claim 6, wherein the thermosetting resins and reactive resins are not softened or melted until they are heat-decomposed.
Claim 9
Dependent Claim
31 words
A method for preparing a magnetic recording medium as in claim 1, wherein 10 to 200 parts by weight of binders are added to 100 parts by weight of ferromagnetic powders.
Claim 10
Dependent Claim
22 words
A method for preparing a magnetic recording medium as in claim 4, wherein the binder is used in combination with additive agents.
Claim 11
Dependent Claim
33 words
A method for preparing a magnetic recording medium as in claim 9, wherein the additive agents are selected from at least one member of the group consisting of dispersing agents, lubricants and abrasives.
Claim 12
Dependent Claim
31 words
A method for preparing a magnetic recording medium as in claim 10, wherein 1 to 20 parts by weight of dispersing agent is added to 100 parts by weight of binder.
Claim 13
Dependent Claim
30 words
A method for preparing a magnetic recording medium as in claim 10, wherein 0.2 to 20 parts by weight to lubricants are added to 100 parts by weight of binder.
Claim 14
Dependent Claim
25 words
A method for preparing a magnetic recording medium as in claim 10, wherein the abrasives have an average particle diameter of 0.05 to 5 microns.
Claim 15
Dependent Claim
25 words
A method for preparing a magnetic recording medium as in claim 10, wherein the abrasives have an average particle diameter of 0.1 to 2 microns.
Claim 16
Dependent Claim
30 words
A method for preparing a magnetic recording medium as in claim 10, wherein 7 to 20 parts by weight of abrasives are added to 100 parts by weight of binder.
Claim 17
Dependent Claim
26 words
A method for preparing a magnetic recording medium as in claim 1, wherein the magnetic coating layer comprises ferromagnetic fine particles, binder and an organic solvent.
Claim 18
Dependent Claim
24 words
A method for preparing a magnetic recording medium as in claim 1, wherein the non-magnetic support has a thickness of 5 to 50 microns.
Claim 19
Dependent Claim
24 words
A method for preparing a magnetic recording medium as in claim 1, wherein the non-magnetic support has a thickness of 10 to 40 microns.
Claim 20
Dependent Claim
28 words
A method for preparing a magnetic recording medium as in claim 1, wherein the non-magnetic support is selected from the group consisting of polyesters, polyolefins, and cellulose derivatives.
Claim 21
Dependent Claim
18 words
A method for preparing a magnetic recording medium as in claim 19, wherein the polyester is polyethylene terephthalate.
Claim 22
Dependent Claim
17 words
A method for preparing a magnetic recording medium as in claim 19, wherein the polyolefin is polypropylene.
Claim 23
Dependent Claim
21 words
A method for preparing a magnetic recording medium as in claim 1, wherein the magnetic field is 50 to 5000 gauss.
Claim 24
Dependent Claim
26 words
A method for preparing a magnetic recording medium as in claim 1, wherein the flexible smoothing sheet has a thickness of 4 microns to 120 microns.
References Cited (Backward Citations)
JPS5713051A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-10-14 | 1989-04-15 | 1989-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-10-14 | 1993-04-15 | 1993-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-10-14 | 1997-04-15 | 1997-10-15 | $7700.00 | Window Closed / Lapsed |