US4439486A
Expired / Lapsed
US
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Magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1982-03-12
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Granted: 1984-03-27
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Expires: 2002-03-12
Abstract
Abstract A magnetic recording medium having a magnetic layer formed on a nonmagnetic base is disclosed. The magnetic layer comprises ferromagnetic particles having a specific surface area of 30 m 2 /g or more. The particles are dispersed in a binder which comprises a thermoplastic polyurethane resin or polyurethane prepolymer and nitrocellulose having an average degree of polymerization of about 50 to 300 and a degree of nitration of 10.7 to 13.0.
Inventors
- 👤 Yasuyuki Yamada
- 👤 Masaaki Fujiyama
- 👤 Nobuo Tsuji
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 03:30
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; Y10T428/26; Y10T428/263; Y10T428/264; Y10T428/265; Y10T428/31504; Y10T428/31551; Y10T428/31609; Y10T428/31678; Y10T428/31703
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
88 words
A magnetic recording medium, comprising: a nonmagnetic support base; and a magnetic layer formed on a surface of the base, the magnetic layer consisting essentially of: ferromagnetic particles having a specific surface area of 30 m 2 /g or more; and a binder consisting essentially of a nitrocellulose having an average degree of polymerization of about 50 to 300 and a degree of nitration of 10.7 to 13.0, a polymer selected from the group consisting of a thermoplastic polyurethane resin and a polyurethane prepolymer, and a polyisocyanate compound.
Claim 2
Dependent Claim
88 words
A magnetic recording medium, comprising: a nonmagnetic support base; and a magnetic layer formed on a surface of the base, the magnetic layer consisting essentially of: ferromagnetic particles having a specific surface area of 30 m 2 /g or more; and a binder consisting essentially of a nitrocellulose having an average degree of polymerization of about 50 to 300 and a degree of nitration of 10.7 to 13.0, a polymer selected from the group consisting of a thermoplastic polyurethane resin and a polyurethane prepolymer, and a polyisocyanate compound.
Claim 3
Dependent Claim
29 words
A magnetic recording medium as claimed in claim 1, wherein said polymer is a thermoplastic polyurethane resin having a number average molecular weight of from about 5,000 to 100,000.
Claim 4
Dependent Claim
21 words
A magnetic recording medium as claimed in claim 2, wherein said number average molecular weight is from about 9,000 to 70,000.
Claim 5
Dependent Claim
28 words
A magnetic recording medium as claimed in claim 1, wherein said polymer is a polyurethane prepolymer having a number average molecular weight of from about 1,000 to 10,000.
Claim 6
Dependent Claim
21 words
A magnetic recording medium as claimed in claim 4, wherein said number average molecular weight is from about 2,000 to 9,000.
Claim 7
Dependent Claim
34 words
A magnetic recording medium as claimed in claim 1, wherein said nitrocellulose has an average degree of polymerization of from about 80 to 200 and a degree of nitration of from 11.5 to 12.2.
Claim 8
Dependent Claim
27 words
A magnetic recording medium as claimed in claim 1, wherein the weight ratio of said nitrocellulose to said polymer is in the range of 1:9 to 1:1.
Claim 9
Dependent Claim
18 words
A magnetic recording medium as claimed in claim 7, wherein said weight ratio is from 2:8 to 3:7.
Claim 10
Dependent Claim
39 words
A magnetic recording medium as claimed in claim 1, wherein said polyisocyanate compound is contained in an amount of 5 to 50 parts by weight per 100 parts by weight of the mixture of said nitrocellulose and said polymer.
Claim 11
Dependent Claim
39 words
A magnetic recording medium as claimed in claim 9, wherein said polyisocyanate compound is contained in an amount of 10 to 30 parts by weight per 100 parts by weight of the mixture of said nitrocellulose and said polymer.
Claim 12
Dependent Claim
33 words
A magnetic recording medium as claimed in claim 1, wherein said binder is contained in an amount of 17 to 50 parts by weight per 100 parts by weight of the ferromagnetic particles.
Claim 13
Dependent Claim
33 words
A magnetic recording medium as claimed in claim 1, wherein said binder is contained in an amount of 23 to 30 parts by weight per 100 parts by weight of the ferromagnetic particles.
Claim 14
Dependent Claim
21 words
A magnetic recording as claimed in claim 1, wherein the magnetic layer has a dry thickness of from 1 to 18μ.
Claim 15
Dependent Claim
56 words
A magnetic recording medium as claimed in claim 1, wherein said binder consists of a nitrocellulose having an average degree of polymerization of about 50 to 300 and a degree of nitration of 10.7 to 13.0, a polymer selected from the group consisting of a thermoplastic polyurethane resin and a polyurethane prepolymer, and a polyisocyanate compound.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-03-27 | 1987-09-26 | 1988-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-03-27 | 1991-09-26 | 1992-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-03-27 | 1995-09-26 | 1996-03-27 | $7700.00 | Window Closed / Lapsed |