US4668355A
Expired / Lapsed
US
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Solutions for extracting magnetic particles
Assignee: Olin Corp
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Filing: 1985-09-09
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Granted: 1987-05-26
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Expires: 2005-09-09
Abstract
Abstract The present invention relates to solutions for extracting magnetic particles from a surrounding matrix. The solutions extract the magnetic particles by dissolving the surrounding matrix and leaving the magnetic particles. Useful solutions include aqueous citrate solutions and aqueous solutions containing free ammonia. The magnetic particles produced using the solutions of the present invention have particular utility in magnetic recording media.
Inventors
- 👤 Lifun Lin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:22
CPC Classifications
B; B22; B22F; B22F9/00; B22F9/16; B22F1/00; B22F1/06; B22F1/062; G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70605; G11B5/712; B22F2998/00; B22F2998/10
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
51 words
A solution for extracting magnetic particles from a surrounding matrix by dissolving said surrounding matrix without significantly dissolving said magnetic particles comprising an aqueous citrate solution initially having a citrate ion concentration in the range of from about 0.5 M to about 3 M and a pH greater than about 3.
Claim 2
Dependent Claim
51 words
A solution for extracting magnetic particles from a surrounding matrix by dissolving said surrounding matrix without significantly dissolving said magnetic particles comprising an aqueous citrate solution initially having a citrate ion concentration in the range of from about 0.5 M to about 3 M and a pH greater than about 3.
Claim 3
Dependent Claim
31 words
The solution of claim 1 further comprising: said citrate ion concentration being in the range of about 1 M to about 2 M and said pH being greater than about 4.
Claim 4
Dependent Claim
27 words
The solution of claim 1 further comprising: said citrate ions being present in the form of at least one of an alkaline metal citrate and citric acid.
Claim 5
Dependent Claim
16 words
The solution of claim 1 further including a concentration of copper greater than about 0.3 M.
Claim 6
Dependent Claim
73 words
A solution for extracting magnetic particles from a surrounding copper matrix by dissolving said copper matrix without substantially dissolving said magnetic particles comprising: an aqueous solution initially containing from about 0.5 M to about 3 M of at least one organic complexing agent selected from the group consisting of formates, acetates and citrates and a concentration of copper greater than about 0.3 M; and said solution having a pH greater than about 3.
Claim 7
Dependent Claim
73 words
A solution for extracting magnetic particles from a surrounding copper matrix by dissolving said copper matrix without substantially dissolving said magnetic particles comprising: an aqueous solution initially containing from about 0.5 M to about 3 M of at least one organic complexing agent selected from the group consisting of formates, acetates and citrates and a concentration of copper greater than about 0.3 M; and said solution having a pH greater than about 3.
Claim 8
Dependent Claim
35 words
The solution of claim 5 wherein said organic complexing agent comprises from about 0.5 M to about 3 M of a citrate selected from the group consisting of an alkaline metal citrate and citric acid.
Claim 9
Dependent Claim
28 words
The solution of claim 5 further containing an effective amount of at least one of sodium hydroxide and ammonium hydroxide for maintaining said pH at a desired level.
Claim 10
Dependent Claim
67 words
A process for producing free magnetic particles, said process comprising: providing a material having a plurality of magnetic particles surrounded by a matrix; and dissolving said matrix without significantly dissolving said magnetic particles by immersing said material in an aqueous citrate solution initially having a citrate ion concentration in the range of from about 0.5 M to about 3.0 M and a pH greater than about 3.
Claim 11
Dependent Claim
67 words
A process for producing free magnetic particles, said process comprising: providing a material having a plurality of magnetic particles surrounded by a matrix; and dissolving said matrix without significantly dissolving said magnetic particles by immersing said material in an aqueous citrate solution initially having a citrate ion concentration in the range of from about 0.5 M to about 3.0 M and a pH greater than about 3.
Claim 12
Dependent Claim
20 words
The process of claim 8 wherein said dissolving step further includes forming a passive layer about each said magnetic particle.
Claim 13
Dependent Claim
41 words
The process of claim 8 wherein said dissolving step comprises immersing said material in an aqueous solution having an initial citrate ion concentration in the range of about 1 M to about 2 M and a pH greater than about 4.
Claim 14
Dependent Claim
35 words
The process of claim 8 wherein said dissolving step further includes: providing at least two electrodes, each said electrode being at least partially immersed in said solution; and applying an electrical current between said electrodes.
Claim 15
Dependent Claim
25 words
The process of claim 8 further including maintaining said solution at a temperature in the range of from about room temperature to about 50° C.
References Cited (Backward Citations)
AU133638A
Cited
US3649489A
Cited
US4257830A
Cited
US4274865A
Cited
US4290799A
Cited
US4404074A
Cited
US4461685A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-05-25 | 1990-11-24 | 1991-05-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-05-25 | 1994-11-24 | 1995-05-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-05-25 | 1998-11-24 | 1999-05-26 | $7700.00 | Window Closed / Lapsed |