US5254404A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Magnetic recording medium comprising ferromagnetic particles having crystallite size of less than 450 angstroms and a specified polyurethane binder
Assignee: Fujifilm Corp
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Filing: 1992-05-13
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Granted: 1993-10-19
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Expires: 2012-05-13
Abstract
Abstract A magnetic recording medium is disclosed, comprising a non-magnetic support having thereon at least one magnetic recording layer comprising a dispersion of ferromagnetic particles in a binder, said binder comprising the combination of a polyisocyanate and a polyurethane binder comprising at least one terminal hydroxyl group at each end of the polyurethane molecule, said polyurethane binder being prepared by reacting (a) a polyurethane prepolymer comprising at least one terminal isocyanate group at each end of the polyurethane prepolymer molecule, said polyurethane prepolymer having a glass transition temperature of at least 0° C. and containing a polar group, with (b) a compound comprising at least one terminal hydroxyl group at each end of the polymer molecule and having a glass transition temperature of -30° C. or less.
Inventors
- 👤 Hiroshi Hashimoto
- 👤 Akira Ushimaru
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 04:09
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/702; G11B5/7021; G11B5/7022; Y; Y10; Y10S; Y10S428/00; Y10S428/90; Y10T; Y10T428/00; Y10T428/25; Y10T428/256; Y10T428/257; Y10T428/31504; Y10T428/31551; Y10T428/31609
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
137 words
A magnetic recording medium comprising a non-magnetic support having thereon at least one magnetic recording layer comprising a dispersion of ferromagnetic particles in a binder, said ferromagnetic particles having a crystalline size of 450Å or less, said binder comprising the combination of a polyisocyanate and a polyurethane binder consisting essentially of at least one terminal hydroxyl group at each end of the polyurethane molecule, said polyurethane binder being prepared by reacting (a) a polyurethane prepolymer comprising at least one terminal isocyanate group at each end of the polyurethane prepolymer molecule, said polyurethane prepolymer having a glass transition temperature of at least 0° C. and containing a polar group, with (b) a compound comprising at least one terminal hydroxyl group at each end of the polymer molecule and having a glass transition temperature of -30° C. or less.
Claim 2
Dependent Claim
137 words
A magnetic recording medium comprising a non-magnetic support having thereon at least one magnetic recording layer comprising a dispersion of ferromagnetic particles in a binder, said ferromagnetic particles having a crystalline size of 450Å or less, said binder comprising the combination of a polyisocyanate and a polyurethane binder consisting essentially of at least one terminal hydroxyl group at each end of the polyurethane molecule, said polyurethane binder being prepared by reacting (a) a polyurethane prepolymer comprising at least one terminal isocyanate group at each end of the polyurethane prepolymer molecule, said polyurethane prepolymer having a glass transition temperature of at least 0° C. and containing a polar group, with (b) a compound comprising at least one terminal hydroxyl group at each end of the polymer molecule and having a glass transition temperature of -30° C. or less.
Claim 3
Dependent Claim
22 words
The magnetic recording medium as claimed in claim 1, wherein said binder further contains a vinyl chloride copolymer containing a polar group.
Claim 4
Dependent Claim
75 words
The magnetic recording medium as claimed in claim 1, wherein said polar group is at least one polar group selected from the group consisting of --SO 3 M, --OSO 3 M, --PO 3 M 2 , --OPO 3 M 2 , --COOM, NR 2 , and --N + R 3 X - , wherein M represents hydrogen atom, an alkali metal, or ammonium group, R represents an alkyl group, and X represents a halogen atom.
Claim 5
Dependent Claim
75 words
The magnetic recording medium as claimed in claim 2, wherein said polar group is at least one polar group selected from the group consisting of --SO 3 M, --OSO 3 M, --PO 3 M 2 , --OPO 3 M 2 , --COOM, --NR 2 , and --N + R 3 X - , wherein M represents hydrogen atom, an alkali metal, or ammonium group, R represents an alkyl group, and X represents a halogen atom.
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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) | 1996-10-18 | 1997-04-19 | 1997-10-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-10-18 | 2001-04-19 | 2001-10-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-10-18 | 2005-04-19 | 2005-10-19 | $7700.00 | Window Closed / Lapsed |