Patent US4404253A successfully refreshed from Google Patents.
US4404253A
Expired / Lapsed
US
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Magnetic recording medium
Assignee: Emtec Magnetics GmbH
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Filing: 1982-02-25
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Granted: 1983-09-13
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Expires: 2002-02-25
Abstract
Abstract Magnetic recording medium using water as dispersion medium. The magnetic layer comprises as binder an aqueous dispersion of polyurethane having functional groups capable of salt formation and a magnetic pigment. The volumetric ratio of magnetic pigment to polyurethane in terms of solids content is in the range of 0.7:1 to 1.4:1.
Inventors
- 👤 Robert Kohler
- 👤 Karlchristian Schilffarth
- 👤 Heinrich Kober
- 👤 Burkhard Nippe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 22:54
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/702; G11B5/7021; G11B5/7013; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/254; Y10T428/256; Y10T428/257; Y10T428/31504; Y10T428/31551; Y10T428/31609
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
101 words
A magnetic recording medium comprised of a flexible support and at least one magnetic layer on said support comprising a water dispersible binder and magnetic pigments wherein the improvement comprises the magnetic layer includes a binder comprised of anionic polyurethane ionomers particles containing from 0.02 to 13% by weight of SO 3 - groups, being dispersed in water with dispersing agents, and said magnetic pigments and said polyurethane ionomer particles having a particle size of 20 nm to 400 nm, the volumetric ratio of magnetic pigment to polyurethane, based on the solids content, being in the range of 0.7:1 to 1.4:1.
Claim 2
Dependent Claim
101 words
A magnetic recording medium comprised of a flexible support and at least one magnetic layer on said support comprising a water dispersible binder and magnetic pigments wherein the improvement comprises the magnetic layer includes a binder comprised of anionic polyurethane ionomers particles containing from 0.02 to 13% by weight of SO 3 - groups, being dispersed in water with dispersing agents, and said magnetic pigments and said polyurethane ionomer particles having a particle size of 20 nm to 400 nm, the volumetric ratio of magnetic pigment to polyurethane, based on the solids content, being in the range of 0.7:1 to 1.4:1.
Claim 3
Dependent Claim
129 words
A magnetic recording medium comprised of a flexible support and at least one magnetic layer on said support comprising a water dispersible binder and magnetic pigments wherein the improvement comprises the magnetic layer includes a binder comprised of anionic polyurethane ionomers particles containing from 0.02 to 13% by weight of SO 3 - groups, being dispersed in water with a dispersing agent selected from the group consisting of sodium polyphosphate, sodium hexametaphosphate, a salt of polyacrylic or polymethacrylic acid and a block polymer of polyethylene oxide and polypropylene oxide, and said magnetic pigments and said polyurethane ionomer particles having a particle size of 20 nm to 400 nm, the volumetric ratio of magnetic pigment to polyurethane, based on the solids content, being in the range of 0.7:1 to 1.4:1.
Claim 4
Dependent Claim
129 words
A magnetic recording medium comprised of a flexible support and at least one magnetic layer on said support comprising a water dispersible binder and magnetic pigments wherein the improvement comprises the magnetic layer includes a binder comprised of anionic polyurethane ionomers particles containing from 0.02 to 13% by weight of SO 3 - groups, being dispersed in water with a dispersing agent selected from the group consisting of sodium polyphosphate, sodium hexametaphosphate, a salt of polyacrylic or polymethacrylic acid and a block polymer of polyethylene oxide and polypropylene oxide, and said magnetic pigments and said polyurethane ionomer particles having a particle size of 20 nm to 400 nm, the volumetric ratio of magnetic pigment to polyurethane, based on the solids content, being in the range of 0.7:1 to 1.4:1.
Claim 5
Dependent Claim
26 words
Magnetic recording medium according to claim 2, characterised in that the anionic polyurethane ionomer preferably contains 0.02 to 3% by weight of SO 3 - groups.
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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) | 1986-09-12 | 1987-03-14 | 1987-09-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-09-12 | 1991-03-14 | 1991-09-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-09-12 | 1995-03-14 | 1995-09-13 | $7700.00 | Window Closed / Lapsed |