EP0047321B1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Magnetic recording medium
Assignee: TDK Corp
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Filing: 1981-03-02
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Granted: 1985-08-14
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Expires: 2001-03-02
Abstract
Abstract A magnetic recording medium useful for magnetic tape, magnetic cords, magnetic discs, etc., which is prepared by using (A) a radiation-hardenable compound having a molecular weight of not less than 5000, preferably not less than 8000, and having two or more unsaturated double bonds, (B) a radiation-hardenable compound having a molecular weight of not less than 400 and less than 5000, preferably 600 to 3000, and having one or more unsaturated double bonds, and (C) a radiation-hardenable compound having a molecular weight of less than 400 and having one or more unsaturated double bonds, coating a magnetic paint on a base material, the magnetic paint primarily containing magnetic particles prepared by compounding (A) and (B), or (A), (B) and (C), and a solvent, and, after preliminary drying, irradiating it.
Inventors
- 👤 Akira Ohtsuki
- 👤 Ryozo Konno
- 👤 Makio Sugai
- 👤 Yasuo Imaoka
- 👤 Yuichi Kubota
- 👤 Kazushi Tanaka
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 04:30
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/702; G11B5/7026; C; C08; C08G; C08G18/00; C08G18/06; C08G18/28; C08G18/40; C08G18/62; C08G18/6212; C08G18/67; C08G18/671; C08G18/70; C08G18/81; C08G18/8141; C08G18/815; C08G18/8158; G11B5/7021; G11B5/7022
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
127 words
A magnetic coating composition for a magnetic recording medium, which consists sssentially of a binder, magnetic particles, and solvent, said binder comprising either a combination of (A) 20-95 wt% of a compound containing at least two unsaturated double bonds curable upon exposure to radio-active rays and having a molecular weight of not less than 5000, preferably not less than 8000, and (B) 5-80 wt% of a compound containing at least one radiation-curable unsaturated double bond and having a molecular weight of not less than 400 and less than 5000, preferably in the range of 600-3000, or a combination of the compounds (A), (B) and (C) 0-50 wt% of a compound containing at least one radiation-curable, unsaturated double bond and having a molecular weight of less than 400.
Claim 2
Dependent Claim
127 words
A magnetic coating composition for a magnetic recording medium, which consists sssentially of a binder, magnetic particles, and solvent, said binder comprising either a combination of (A) 20-95 wt% of a compound containing at least two unsaturated double bonds curable upon exposure to radio-active rays and having a molecular weight of not less than 5000, preferably not less than 8000, and (B) 5-80 wt% of a compound containing at least one radiation-curable unsaturated double bond and having a molecular weight of not less than 400 and less than 5000, preferably in the range of 600-3000, or a combination of the compounds (A), (B) and (C) 0-50 wt% of a compound containing at least one radiation-curable, unsaturated double bond and having a molecular weight of less than 400.
Claim 3
Dependent Claim
29 words
A magnetic coating composition according to claim 1 wherein said compounds (A), (B) and (C) are contained in the ratios of 50-90 wt%, 10-50 wt% and 5-20 wt%, respectively.
Claim 4
Dependent Claim
52 words
A magnetic coating composition according to claim 1 or 2 wherein said compound (A) is one prepared by reacting a partly saponified vinyl chloride-vinyl acetate copolymer with a polyisocyanate compound and then reacting the resulting isocyanate-containing compound with an acrylic or methacrylic compound having a functional group reactive with the isocyanate group.
Claim 5
Dependent Claim
48 words
A magnetic coating composition according to claim 1, 2 or 3 wherein said compound (B) is one prepared by reacting a polyol with a polyisocyanate compound and then reacting the resulting isocyanate-containing compound with an acrylic or methacrylic compound having a functional group reactive with the isocyanate group.
Claim 6
Dependent Claim
27 words
A magnetic coating composition according to any of claims 1 to 4 wherein said binder further comprises a thermoplastic resin free of any radiation-curable, unsaturated double bond.
Claim 7
Dependent Claim
33 words
A magnetic recording medium according to any of claims 1 to 5 wherein said magnetic particles are those of at least one powder selected from among cobalt-modified magnetic iron oxide and alloy powders.
Claim 8
Dependent Claim
157 words
A process for producing a magnetic recording medium comprising a substrate and a magnetic recording layer formed thereon, which comprises applying a magnetic coating composition consisting essentially of a binder, magnetic particles, and solvent, predrying the coating layer, and then irradiating the same with radioactive rays, characterised in that said binder comprises either a combination of (A) 20-95 wt% of a compound containing at least two unsaturated double bonds curable upon exposure to radioactive rays and having a molecular weight of not less than 5000, and preferably not less than 8000, and (B) 5-80 wt% of a compound containing at least one radiation-curable, unsaturated double bond and having q molecular weight of not less than 400 and less than 5000, preferably in the range of 600-3000, or a combination of the compounds (A), (B) and (C) 0-50 wt% of a compound containing at least one radiation-curable, unsaturated double bond and having molecular weight of less than 400.
Claim 9
Dependent Claim
157 words
A process for producing a magnetic recording medium comprising a substrate and a magnetic recording layer formed thereon, which comprises applying a magnetic coating composition consisting essentially of a binder, magnetic particles, and solvent, predrying the coating layer, and then irradiating the same with radioactive rays, characterised in that said binder comprises either a combination of (A) 20-95 wt% of a compound containing at least two unsaturated double bonds curable upon exposure to radioactive rays and having a molecular weight of not less than 5000, and preferably not less than 8000, and (B) 5-80 wt% of a compound containing at least one radiation-curable, unsaturated double bond and having q molecular weight of not less than 400 and less than 5000, preferably in the range of 600-3000, or a combination of the compounds (A), (B) and (C) 0-50 wt% of a compound containing at least one radiation-curable, unsaturated double bond and having molecular weight of less than 400.
Claim 10
Dependent Claim
29 words
A process according to claim 7, characterised in that the compound (A), (B) and (C) are contained in the ratios of 50-90 wt%, 10-50 wt% and 5-20 wt%, respectively.
Claim 11
Dependent Claim
52 words
A process according to claim 7 or 8, characterised in that said compound (A) is one prepared by reacting a partly saponified vinyl chloride-vinyl acetate copolymer with a polyisocyanate compound and then reacting the resulting isocyanate-containing compound with an acrylic or methacrylic compound having a functional group reactive with the isocyanate group.
Claim 12
Dependent Claim
48 words
A process according to claim 7, 8 or 9, characterised in that said compound (B) is one prepared by reacting a polyol with a polyisocyanate compound and the reacting the resulting isocyanate-containing compound with an acrylic or methacrylic compound having a functional group reactive with the isocyanate group.
Claim 13
Dependent Claim
27 words
A process according to any of claims 7 to 10, characterised in that said binder further comprises a thermoplastic resin free of any radiation-curable, unsaturated double bond.
Claim 14
Dependent Claim
31 words
A process according to any of claims 7 to 11, wherein said magnetic particles are those of at least one powder selected from among cobalt-modified magnetic iron oxide and alloy powders.
Claim 15
Dependent Claim
24 words
A process according to any of claims 7 to 12, wherein said irradiation with radioactive rays is carried out in an inert gas stream.
References Cited (Backward Citations)
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