Patent EP0048456A2 successfully refreshed from Google Patents.
EP0048456A2
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Process for manufacturing powder for magnetic recording medium
Assignee: Toshiba Corp
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Filing: 1981-09-17
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Granted: —
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Expires: 2001-09-17
Abstract
Abstract A process for manufacturing a hexagonal ferrite magnetic powder for a magnetic recording medium involves rapidly cooling a molten material of a glass-forming component and a hexagonal ferrite-forming component to obtain glass flakes, heating the glass flakes to precipitate ferrite fine grains, incompletely dissolving the glass flakes with an acid or boiling water, and separating and recovering the fine grains in the presence of a dispersing agent.
Inventors
- 👤 Yoshiyasu Koike
- 👤 Osamu Kubo
- 👤 Tadashi Ido
- 👤 Masanobu Uwaha
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-05 15:24
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70642; G11B5/70678
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
111 words
A process for manufacturing a hexagonal ferrite magnetic powder for a magnetic recording medium comprising the steps of: . uniformly mixing and melting a hexagonal ferrite-forming component and a glass-forming component as a precipitating base material of fine grains of the hexagonal ferrite; rapidly cooling the resultant molten material to provide glass flakes; thermally treating the glass flakes to precipitate the fine grains of the hexagonal ferrite therein; incompletely dissolving the glass flakes containing the precipitated fine grains with boiling water or an acid which is capable of dissolving glass; and separating and recovering the precipitated fine grains from the incompletely dissolved glass flakes in the presence of a dispersing agent.
Claim 2
Dependent Claim
111 words
A process for manufacturing a hexagonal ferrite magnetic powder for a magnetic recording medium comprising the steps of: . uniformly mixing and melting a hexagonal ferrite-forming component and a glass-forming component as a precipitating base material of fine grains of the hexagonal ferrite; rapidly cooling the resultant molten material to provide glass flakes; thermally treating the glass flakes to precipitate the fine grains of the hexagonal ferrite therein; incompletely dissolving the glass flakes containing the precipitated fine grains with boiling water or an acid which is capable of dissolving glass; and separating and recovering the precipitated fine grains from the incompletely dissolved glass flakes in the presence of a dispersing agent.
Claim 3
Dependent Claim
77 words
A process according to claim 1, wherein the dispersing agent is a phosphoric ester of the general formula: wherein X and Y represent (̵OCH 2 CH 2 )̵ n H (where n is an integer of 1 to 50), -OR (where R is an alkyl group or an alkyl aryl group), or + OCH 2 CH 2 )̵ n OR (where n and R are as defined above); and Z is -OH or any of said groups.
Claim 4
Dependent Claim
45 words
A process according to claim 1, wherein the dispersing agent is a compound selected from the group consisting of lecithin, amine compounds, ammonium compounds, higher fatty acids, metallic soaps of the higher fatty acids, higher fatty acid esters, alkyl sulfonates, and polyoxyethylene ethers and esters.
Claim 5
Dependent Claim
44 words
A process according to claim 1 or 2, wherein the dispersing agent is added in an amount of 2 to 8 parts by weight based on 100 parts by weight of the fine grains in the glass flakes before incompletely dissolving the glass flakes.
Claim 6
Dependent Claim
23 words
A process according to claim 1, wherein the dispersing agent is added to the glass flakes after the glass flakes are incompletely dissolved.
Claim 7
Dependent Claim
30 words
A process according to claim 1, wherein the dispersing agent is added to the glass flakes together with an acid and boiling water before the glass flakes are incompletely dissolved.
Claim 8
Dependent Claim
34 words
A process according to claim 1, wherein the ferrite-forming component comprises basic components of BaO and Fe 2 0 3 , and substituting components of TiO Z and CoO for control of coercive force.
Claim 9
Dependent Claim
21 words
A process according to claim 1, wherein the glass-forming component is B 2 O 3 or H 3 B0 4 .
Claim 10
Dependent Claim
23 words
A process according to claim 1, wherein the temperature for thermally treating the glass flakes is within the range of 550 to 900°C.
Claim 11
Dependent Claim
21 words
A process according to claim 1, wherein the acid for incompletely dissolving the glass flakes is acetic acid or hydrochloric acid.
Claim 12
Dependent Claim
21 words
A process according to claim 1, wherein glass is present between the ferrite fine grains in the incompletely dissolved glass flakes.
References Cited (Backward Citations)
No citation records indexed.
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