US3905841A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of improving dispersability of small metallic magnetic particles in organic resin binders
Assignee: International Business Machines Corp
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Filing: 1973-08-30
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Granted: 1975-09-16
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Expires: 1993-08-30
Abstract
Abstract Magnetic cobalt-phosphorous particles formed by chemical oxidation-reduction are found to agglomerate and not to disperse homogeneously when mixed with organic resin binders. When the same type of cobalt-phosphorous particles are treated with a sulfuric acid containing solution and then incorporated into an organic resin binder, the resulting mixture exhibits homogeneous dispersion characteristics.
Inventors
- 👤 Alexander Simonetti
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 04:02
CPC Classifications
H; H01; H01F; H01F1/00; H01F1/01; H01F1/03; H01F1/032; H01F1/04; H01F1/06; B; B22; B22F; B22F9/00; B22F9/16; B22F9/18; B22F9/24
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
81 words
THE METHOD OF PRODUCING FINELY DIVIDED METALLIC MAGNETIC COBALT-PHOSPHOROUS PARTICLES HAVING SUBSTANTIALLY HOMOGENEOUS DISPERSABILITY IN ORGANIC RESIN BINDERS, SAID COBALTPHOSPHOROUS HAVING BEEN PREPARED BY REACTING A SOLUTION INCLUDING HYPOPHOSPHITE ANION REDUCING AGENT, AND COBALT CATIONS WHICH ARE REDUCEABLE TO COBALT METAL BY SAID HYPOPHOSPHITE, WHEREIN THE IMPROVEMENT COMPRISES, REACTING SAID COBALT-PHOSPHOROUS PARTICLES WITH SULFURIC ACID TO REDUCE THE RELATIVE PERCENTAGE OF COBALT AND INCREASE THE RELATIVE PERCENTAGE OF PHOTOSPHOROUS AND TO IMPROVE THE DISPERSION CHARACTERISTICS OF SAID COBALT-PHOSPHOROUS IN ORGANIC RESIN.
Claim 2
Independent Claim
81 words
THE METHOD OF PRODUCING FINELY DIVIDED METALLIC MAGNETIC COBALT-PHOSPHOROUS PARTICLES HAVING SUBSTANTIALLY HOMOGENEOUS DISPERSABILITY IN ORGANIC RESIN BINDERS, SAID COBALTPHOSPHOROUS HAVING BEEN PREPARED BY REACTING A SOLUTION INCLUDING HYPOPHOSPHITE ANION REDUCING AGENT, AND COBALT CATIONS WHICH ARE REDUCEABLE TO COBALT METAL BY SAID HYPOPHOSPHITE, WHEREIN THE IMPROVEMENT COMPRISES, REACTING SAID COBALT-PHOSPHOROUS PARTICLES WITH SULFURIC ACID TO REDUCE THE RELATIVE PERCENTAGE OF COBALT AND INCREASE THE RELATIVE PERCENTAGE OF PHOTOSPHOROUS AND TO IMPROVE THE DISPERSION CHARACTERISTICS OF SAID COBALT-PHOSPHOROUS IN ORGANIC RESIN.
Claim 3
Dependent Claim
21 words
The method of claim 1 wherein the total dry weight of the cobalt-phosphorous particles is reduced by at least about 10%.
Claim 4
Dependent Claim
25 words
The method of claim 1 wherein the total dry weight of the cobalt-phosphorous particles is reduced within the range of about 35 to about 50%.
Claim 5
Dependent Claim
35 words
The method of claim 1 wherein, after the particles are treated with sulfuric acid, said particles are maintained moist with an organic solvent and dried in a non-oxidizing atmosphere in the presence of carbon dioxide.
Claim 6
Dependent Claim
13 words
The method of claim 1 wherein the reaction is initiated at about 45*C.
Claim 7
Dependent Claim
12 words
The method of claim 1 wherein aluminum chloride is an additional etchant.
Claim 8
Independent Claim
111 words
A method for producing finely divided metallic magnetic cobalt-phosphorous particles which are easily homogeneously dispersable in organic resin binders, said process comprising: preparing cobalt-phosphorous particles from a reaction mixture consisting essentially of reduceable cobalt cations and hypophosphite anions as a reducing agent; separating the resulting cobalt-phosphorous particles from said reaction mixture; providing sulfuric acid a volume and concentration sufficient to react with and dissolve from about 35 to about 50%, by weight, of said cobalt-phosphorous; reacting said sulfuric acid and said cobalt-phosphorous particles stoichiometrically at a temperature of about 45*C; and then removing the remaining cobalt-phosphorous particles from solution and drying them under nonoxidizing conditions in the presence of carbon dioxide.
Claim 9
Independent Claim
111 words
A method for producing finely divided metallic magnetic cobalt-phosphorous particles which are easily homogeneously dispersable in organic resin binders, said process comprising: preparing cobalt-phosphorous particles from a reaction mixture consisting essentially of reduceable cobalt cations and hypophosphite anions as a reducing agent; separating the resulting cobalt-phosphorous particles from said reaction mixture; providing sulfuric acid a volume and concentration sufficient to react with and dissolve from about 35 to about 50%, by weight, of said cobalt-phosphorous; reacting said sulfuric acid and said cobalt-phosphorous particles stoichiometrically at a temperature of about 45*C; and then removing the remaining cobalt-phosphorous particles from solution and drying them under nonoxidizing conditions in the presence of carbon dioxide.
Claim 10
Dependent Claim
56 words
A method of making a well dispersed substantially homogeneous coating composition suitable for use in the manufacture of magnetic reducing media consisting of the steps of: bringing together particles produced in accordance with claim 1 and an organic resin binder and solvent; and then mechanically mixing said particles and resin to produce a well dispersed mixture.
Claim 11
Dependent Claim
58 words
A method of making a well dispersed substantially homogeneous coating composition suitable for use in the manufacture of magnetic recording media consisting of the steps of: bringing together particles produced in accordance with claim 7 and an organic resin binder and solvent; and then mechanically mixing said particles and resin to produce a well dispersed substantially homogeneous mixture.
Claim 12
Dependent Claim
10 words
The method of claim 9 wherein the binder is polyurethane.
Claim 13
Dependent Claim
27 words
The method of making a magnetic recording media consisting of the steps of: coating the mixture of claim 10 onto a substrate; and then drying the coating.
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) | 1978-09-15 | 1979-03-17 | 1979-09-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-15 | 1983-03-17 | 1983-09-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-15 | 1987-03-17 | 1987-09-16 | $7700.00 | Window Closed / Lapsed |