US4361627A
Expired / Lapsed
US
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Magnetic recording medium
Assignee: Sony Corp
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Filing: 1980-10-17
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Granted: 1982-11-30
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Expires: 2000-10-17
Abstract
Abstract The present invention relates to a binding agent for a magnetic recording medium which consists of a non-magnetic substrate with a magnetic layer formed thereon. The magnetic layer is composed of a finely divided ferromagnetic substance dispersed in the resinous binding agent. The binding agent consists of: a binder containing a butadiene-containing resin, having an average molecular weight of 1,000-10,000, and being selected from the group consisting of butadiene homopolymers and copolymers of butadiene with acrylonitrile and/or styrene which contains at least 60% by weight of butadiene, with the butadiene-containing resin having on the average more than 1.5 functional end groups per molecule, which are reactive with isocyanate groups; and a polyisocyanate compound having on the average not less than 2 isocyanate groups per molecule, the polyisocyanate compound being present in between 5 and 50 parts by weight, based upon 100 parts by weight of the binder. The use of this binding agent allows for greater dispersion of the ferromagnetic powder as the low molecular weight resin has a high solubility in organic solvents. Further, the butadiene-isocyanate crosslinks formed, act to improve wear resistance and make it possible to obtain a desirable elastic modulus.
Inventors
- 👤 Tsumoru Ohata
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 02:30
CPC Classifications
C; C08; C08G; C08G18/00; C08G18/06; C08G18/28; C08G18/67; C08G18/69; C08G18/692; 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; Y10T428/31504; Y10T428/31551; Y10T428/31609; Y10T428/31855; Y10T428/31931
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
136 words
In a magnetic recording medium comprising a non-magnetic substrate and a magnetic layer formed thereon, said magnetic layer comprising a finely divided ferromagnetic substance dispersed in a resinous binding agent, said binding agent comprising: a binder containing a butadiene-containing resin having an average molecular weight of 1,000 to 10,000 and being selected from the group consisting of butadiene homopolymers and copolymers of butadiene with acrylonitrile and/or styrene which contain at least 60 percent by weight of butadiene, said butadiene-containing resin having on the average more than 1.5 end functional groups reactive with isocyanate groups per molecule; and a polyisocyanate compound having on the average not less than 2 isocyanate groups per molecule, said polyisocyanate compound being present in an amount between 5 and 50 parts by weight based upon 100 parts by weight of said binder.
Claim 2
Dependent Claim
136 words
In a magnetic recording medium comprising a non-magnetic substrate and a magnetic layer formed thereon, said magnetic layer comprising a finely divided ferromagnetic substance dispersed in a resinous binding agent, said binding agent comprising: a binder containing a butadiene-containing resin having an average molecular weight of 1,000 to 10,000 and being selected from the group consisting of butadiene homopolymers and copolymers of butadiene with acrylonitrile and/or styrene which contain at least 60 percent by weight of butadiene, said butadiene-containing resin having on the average more than 1.5 end functional groups reactive with isocyanate groups per molecule; and a polyisocyanate compound having on the average not less than 2 isocyanate groups per molecule, said polyisocyanate compound being present in an amount between 5 and 50 parts by weight based upon 100 parts by weight of said binder.
Claim 3
Dependent Claim
24 words
A magnetic recording medium according to claim 1, wherein said end functional group is a carboxyl group, an amino group or an hydroxyl group.
Claim 4
Dependent Claim
30 words
A magnetic recording medium according to claim 1, wherein said binder contains more than 10 parts by weight of said butadiene-containing resin per 100 parts by weight of said binder.
Claim 5
Dependent Claim
30 words
A magnetic recording medium according to claim 3, wherein said binder contains more than 50 parts by weight of said butadiene-containing resin per 100 parts by weight of said binder.
Claim 6
Dependent Claim
18 words
A magnetic recording medium according to claim 1, wherein said average molecular weight is between 1,000 and 5,000.
Claim 7
Dependent Claim
25 words
A magnetic recording medium according to claim 1, wherein said butadiene-containing resin has, on the average from 1.5 to 4.0 end functional groups per molecule.
Claim 8
Dependent Claim
15 words
A magnetic recording medium according to claim 1, wherein said butadiene-containing resin is butadiene homopolymer.
Claim 9
Dependent Claim
41 words
A magnetic recording medium according to claim 1, wherein the ratio of the number of cross-linking functional groups per molecule of said butadiene-containing resin to the number of isocyanate groups per molecule of said polyisocyanate compound is between 1 and 3.
Claim 10
Dependent Claim
26 words
A magnetic recording medium according to claim 1, wherein said resinous binding agent further contains a chain extender for said polyisocyanate compound consisting of a polyol.
Claim 11
Dependent Claim
46 words
A magnetic recording medium according to claim 1, wherein said binder further contains at least one additional low molecular weight resin selected from the group consisting of vinylchloride-vinyl acetate copolymer, thermoplastic polyurethane resin, phenolic resin, and butadiene-acrylonitrile copolymer, having higher molecular weight than said butadiene-containing resin.
Claim 12
Dependent Claim
41 words
A magnetic recording medium according to claim 1, wherein the ratio of the number of cross-linking functional groups per molecule of said butadiene-containing resin to the number of isocyanate groups per molecule of said polyisocyanate compound is between 1 and 3.
Claim 13
Dependent Claim
190 words
In a magnetic paint for use in the manufacture of magnetic tape which consists in part of a ferromagnetic powder, an organic solvent, and a binder, the improvement which comprises: a binder consisting of a butadiene-containing resin selected from the group consisting of butadiene homopolymers and copolymers of butadiene formed from butadiene and at least one member of a group consisting of acrylonitrile and styrene and which contains at least 60% by weight of butadiene, the butadiene-containing resin having on the average more than 1.5 end functional groups reactive with an isocyanate group per molecule and having an average molecular weight of between 1,000 and 10,000, and a polyisocyanate compound having on the average not less than 2 isocyanate groups per molecule and being present in an amount between 5 and 50 parts by weight based upon 100 parts by weight of the binder, said low molecular weight polybutadiene resin reacted with isocyanate groups providing for greater solubility in an organic solvent and therefore more uniform dispersion of the ferromagnetic powder along with greater crosslinking which maintains the elastic modulus of the magnetic tape at high temperatures and high humidities.
Claim 14
Dependent Claim
190 words
In a magnetic paint for use in the manufacture of magnetic tape which consists in part of a ferromagnetic powder, an organic solvent, and a binder, the improvement which comprises: a binder consisting of a butadiene-containing resin selected from the group consisting of butadiene homopolymers and copolymers of butadiene formed from butadiene and at least one member of a group consisting of acrylonitrile and styrene and which contains at least 60% by weight of butadiene, the butadiene-containing resin having on the average more than 1.5 end functional groups reactive with an isocyanate group per molecule and having an average molecular weight of between 1,000 and 10,000, and a polyisocyanate compound having on the average not less than 2 isocyanate groups per molecule and being present in an amount between 5 and 50 parts by weight based upon 100 parts by weight of the binder, said low molecular weight polybutadiene resin reacted with isocyanate groups providing for greater solubility in an organic solvent and therefore more uniform dispersion of the ferromagnetic powder along with greater crosslinking which maintains the elastic modulus of the magnetic tape at high temperatures and high humidities.
Claim 15
Dependent Claim
224 words
A magnetic recording medium comprising a non-magnetic substrate and a wear resistant magnetic layer formed thereon, said magnetic layer comprising a finely divided ferromagnetic powder dispersed in a resinous binder, said magnetic layer having been produced by the step sequence of: (A) forming a liquid magnetic paint composition comprising: a ferromagnetic powder selected from the group consisting of γ-Fe 2 O 3 , a mixed crystal of γ-Fe 2 O 3 and Fe 3 O 4 doped with cobalt, Fe 3 O 4 doped with cobalt, chromium dioxide, barium ferrite, ferromagnetic alloy powders, and iron nitride, a butadiene-containing resin having an average molecular weight of 1,000 to 10,000 and being selected from the group consisting of butadiene homopolymers and copolymers of butadiene with acrylonitrile and/or styrene which contain at least 60 percent by weight of butadiene, said butadiene-containing resin having on the average more than 1.5 end functional groups reactive with isocyanate groups per molecule, and a solvent for said resin; (B) admixing with said magnetic paint composition, a polyisocyanate compound having on the average not less than 2 isocyanate groups per molecule in an amount ranging from about 5 to 50 parts by weight based upon each 100 parts by weight of said resin; (C) coating with the resulting composition of step (B) onto said non-magnetic substrate and (D) drying the so-coated composition.
Claim 16
Dependent Claim
224 words
A magnetic recording medium comprising a non-magnetic substrate and a wear resistant magnetic layer formed thereon, said magnetic layer comprising a finely divided ferromagnetic powder dispersed in a resinous binder, said magnetic layer having been produced by the step sequence of: (A) forming a liquid magnetic paint composition comprising: a ferromagnetic powder selected from the group consisting of γ-Fe 2 O 3 , a mixed crystal of γ-Fe 2 O 3 and Fe 3 O 4 doped with cobalt, Fe 3 O 4 doped with cobalt, chromium dioxide, barium ferrite, ferromagnetic alloy powders, and iron nitride, a butadiene-containing resin having an average molecular weight of 1,000 to 10,000 and being selected from the group consisting of butadiene homopolymers and copolymers of butadiene with acrylonitrile and/or styrene which contain at least 60 percent by weight of butadiene, said butadiene-containing resin having on the average more than 1.5 end functional groups reactive with isocyanate groups per molecule, and a solvent for said resin; (B) admixing with said magnetic paint composition, a polyisocyanate compound having on the average not less than 2 isocyanate groups per molecule in an amount ranging from about 5 to 50 parts by weight based upon each 100 parts by weight of said resin; (C) coating with the resulting composition of step (B) onto said non-magnetic substrate and (D) drying the so-coated composition.
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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) | 1985-11-29 | 1986-05-31 | 1986-11-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-11-29 | 1990-05-31 | 1990-11-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-11-29 | 1994-05-31 | 1994-11-30 | $7700.00 | Window Closed / Lapsed |