US3901816A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic tape coating
Assignee: Dow Chemical Co
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Filing: 1974-06-17
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Granted: 1975-08-26
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Expires: 1994-06-17
Abstract
Abstract Magnetic tapes are made by applying to a backing film an aqueous dispersion of magnetic particles having dissolved therein cyclic sulfonium zwitterion monomers. Upon removal of the water and/or moderate heating, the monomers polymerize to form a durable matrix having the magnetic particles dispersed therein.
Inventors
- 👤 Mary R Thomas
- 👤 Robert H Lalk
- 👤 Syamalarao Evani
- 👤 Donald L Schmidt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 13:21
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/702
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
50 words
THE COMPOSITION FOR COATING MAGNATIC TAPES COMPRISING AN AQUEOUS DISPERSION OF MAGNETIC PARTICLES HAVING DISSOLVED THEREIN MONOMERIC CYCLIC SULFONIUM ZWITTERIONS IN AN AMOUNT SUFFICIENT, WHEN POLYMERIZED, TO CONSTITUTE A BINDER FOR THE MAGNETIC PARTICLES AND, TOGETHER WITH THE PARTICLES, TO CONSISTUTE A FIRMLY ADHERENT, FLEXIBLE MAGNETIC COATING FOR SAID TAPE.
Claim 2
Dependent Claim
50 words
THE COMPOSITION FOR COATING MAGNATIC TAPES COMPRISING AN AQUEOUS DISPERSION OF MAGNETIC PARTICLES HAVING DISSOLVED THEREIN MONOMERIC CYCLIC SULFONIUM ZWITTERIONS IN AN AMOUNT SUFFICIENT, WHEN POLYMERIZED, TO CONSTITUTE A BINDER FOR THE MAGNETIC PARTICLES AND, TOGETHER WITH THE PARTICLES, TO CONSISTUTE A FIRMLY ADHERENT, FLEXIBLE MAGNETIC COATING FOR SAID TAPE.
Claim 3
Dependent Claim
22 words
The composition of claim 1 wherein the dispersion contains as an active dispersing agent the ammonium salt of a polymeric polycarboxylic acid.
Claim 4
Dependent Claim
24 words
The composition of claim 2 wherein the acid is a polymer or copolymer of acrylic, methacrylic or maleic acid of molecular weight about 2,000-5,000.
Claim 5
Dependent Claim
12 words
The composition of claim 1 wherein the magnetic particles are iron oxide.
Claim 6
Dependent Claim
19 words
The composition of claim 1 wherein about 50-80% by weight of the zwitterions are monofunctional, the remainder being polyfunctional.
Claim 7
Dependent Claim
35 words
The process of making the composition of claim 1 comprising dispersing the magnetic particles in an aqueous solution of a dispersing agent and then adding an aqueous solution of the zwitterions to the resultant dispersion.
References Cited (Backward Citations)
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US3725285A
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US3813363A
Cited
US3749739A
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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) | 1978-08-25 | 1979-02-24 | 1979-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-25 | 1983-02-24 | 1983-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-25 | 1987-02-24 | 1987-08-26 | $7700.00 | Window Closed / Lapsed |