US4454282A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Water-based chromium dioxide magnetic recording media
Assignee: International Business Machines Corp
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Filing: 1983-03-21
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Granted: 1984-06-12
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Expires: 2003-03-21
Abstract
Abstract A stable, non-agglomerating, magnetic recording coating ink, for use in coating a flexible non-magnetic substrate, is made by a two-step process which first mixes finely divided chromium dioxide particles with water and a polymeric surfactant/dispersant agent which has as its major functionality in a side chain, carboxylic acid, as a free acid, ester or amide thereof, and of a relatively low number average molecular weight in the range 500 to 20,000. Only after the particles are dispersed in this slurry is water-based polyurethane binder added to the slurry, as the second step in the process, to form the final ink.
Inventors
- 👤 Richard L. Bradshaw
- 👤 Samuel J. Falcone
- 👤 Alexander Simonetti
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 05:39
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/706; G11B5/70626; G11B5/70636; Y; Y10; Y10S; Y10S428/00; Y10S428/90
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
112 words
A method of making a stable, non-agglomerating, magnetic recording coating ink, which is free of organic solvents, for use in coating a flexible nonmagnetic substrate, said ink having ferromagnetic chromium dioxide particles dispersed in a water-based polyurethane binder, the method comprising the ordered steps of: first dispersing said particles in water and a polymeric surfactant/dispersant agent which has carboxylic acid, as its major functionality in a side chain, as a free acid, sodium salt, ester or amide thereof, and having a number average molecular weight in the range of about 500 to 20,000, to thereby form a slurry; and only thereafter adding said water-based polyurethane binder to said slurry of prior-dispersed particles.
Claim 2
Independent Claim
112 words
A method of making a stable, non-agglomerating, magnetic recording coating ink, which is free of organic solvents, for use in coating a flexible nonmagnetic substrate, said ink having ferromagnetic chromium dioxide particles dispersed in a water-based polyurethane binder, the method comprising the ordered steps of: first dispersing said particles in water and a polymeric surfactant/dispersant agent which has carboxylic acid, as its major functionality in a side chain, as a free acid, sodium salt, ester or amide thereof, and having a number average molecular weight in the range of about 500 to 20,000, to thereby form a slurry; and only thereafter adding said water-based polyurethane binder to said slurry of prior-dispersed particles.
Claim 3
Dependent Claim
18 words
The method of claim 1 wherein said number average molecular weight is in the range 2,000 to 10,000.
Claim 4
Dependent Claim
21 words
The method of claim 2 wherein said agent's carboxylic acid functionality is provided as the alkali metal salt of carboxylic acid.
Claim 5
Dependent Claim
27 words
The method of claim 2 wherein said agent is a half PEG200 ester of maleic acid and acrylamide having a number average molecular weight of about 1,000.
Claim 6
Dependent Claim
24 words
The method of claim 2 wherein said agent is a polymeric acrylic acid sodium salt having a number average molecular weight of about 2000.
Claim 7
Dependent Claim
26 words
The method of claim 2 wherein said agent is a 50/50 copolymer of methacrylic acid and acrylamide, having a number average molecular weight of about 4000.
Claim 8
Dependent Claim
14 words
The method of claim 3 including the step of thereafter adding a crosslinking agent.
Claim 9
Dependent Claim
36 words
The method of claim 6 wherein the ink comprises the weight percentage ranges chromium dioxide 15 to 30; binder 15 to 25; surfactant/dispersant agent 0.2 to 3; crosslinker 0.2 to 3; and water 40 to 60.
Claim 10
Dependent Claim
28 words
The method of claim 7 wherein the ink comprises the weight percentages chromium dioxide about 23; binder about 22; surfactant/dispersant agent 0.5; crosslinker 1; the remainder being water.
Claim 11
Dependent Claim
12 words
The method of claim 8 wherein said binder is a polyester polyurethane.
Claim 12
Dependent Claim
12 words
The method of claim 9 wherein said binder is a polyester polyurethane.
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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) | 1987-06-12 | 1987-12-12 | 1988-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-06-12 | 1991-12-12 | 1992-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-06-12 | 1995-12-12 | 1996-06-12 | $7700.00 | Window Closed / Lapsed |