US5032428A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for producing a magnetic recording medium
Assignee: Fujifilm Holdings Corp
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Filing: 1990-04-20
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Granted: 1991-07-16
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Expires: 2010-04-20
Abstract
Abstract A method for producing a magnetic recording medium is disclosed, comprising coating on a nonmagnetic support a magnetic coating composition for forming a lower magnetic layer and a magnetic coating composition for forming an upper magnetic layer using a wet-on-wet coating method, thereby forming plural magnetic layers, followed by drying, and then conducting heat treatment thereof, wherein the magnetic coating composition for the upper magnetic layer contains ferromagnetic alloy particles are ferromagnetic particles and does not contain a lubricating agent which has polar groups and has a molecular weight of 3000 or less, the magnetic coating composition for the lower magnetic layer contains ferromagnetic iron oxide particles as ferromagnetic particles, a lubricating agent having polar groups and having a molecular weight of 3000 or less, and a curing agent, the lubricating agent as well as the curing agent in the lower magnetic layer being diffused into the upper magnetic layer by the heat treatment.
Inventors
- 👤 Hiroshi Ogawa
- 👤 Shinji Saito
- 👤 Hitoshi Noguchi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 09:55
CPC Classifications
G; G11; G11B; G11B5/00; G11B5/62; G11B5/68; G11B5/70; G11B5/716; G11B5/71; Y; Y10; Y10S; Y10S428/00; Y10S428/90
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
155 words
A method for producing a magnetic recording medium comprising coating on a nonmagnetic support a magnetic coating composition for forming a lower magnetic layer and coating thereon a magnetic coating composition for forming an upper magnetic layer using a wet-on-wet coating method, thereby forming plural magnetic layers, followed by drying, and then conducting heat treatment thereof, wherein said magnetic coating composition for said upper magnetic layer contains ferromagnetic alloy particles as ferromagnetic particles, and does not contain a lubricating agent which has polar groups and has a molecular weight of 3000 or less, said magnetic coating composition for said lower magnetic layer contains ferromagnetic iron oxide particles as ferromagnetic particles, a lubricating agent having polar groups and having a molecular weight of 3000 or less, and a curing agent, and said lubricating agent as well as said curing agent in said lower magnetic layer being diffused into said upper magnetic layer by said heat treatment.
Claim 2
Independent Claim
155 words
A method for producing a magnetic recording medium comprising coating on a nonmagnetic support a magnetic coating composition for forming a lower magnetic layer and coating thereon a magnetic coating composition for forming an upper magnetic layer using a wet-on-wet coating method, thereby forming plural magnetic layers, followed by drying, and then conducting heat treatment thereof, wherein said magnetic coating composition for said upper magnetic layer contains ferromagnetic alloy particles as ferromagnetic particles, and does not contain a lubricating agent which has polar groups and has a molecular weight of 3000 or less, said magnetic coating composition for said lower magnetic layer contains ferromagnetic iron oxide particles as ferromagnetic particles, a lubricating agent having polar groups and having a molecular weight of 3000 or less, and a curing agent, and said lubricating agent as well as said curing agent in said lower magnetic layer being diffused into said upper magnetic layer by said heat treatment.
Claim 3
Dependent Claim
12 words
The process of claim 1, wherein sequential wet-on-wet coating is carried out.
Claim 4
Dependent Claim
12 words
The method of claim 1, wherein simultaneous wet-on-wet coating is carried out.
Claim 5
Dependent Claim
79 words
The method of claim 1, wherein the lubricating agent in the lower magnetic layer contains polar groups selected from the group consisting of --COOX, --SO 3 X, --OSO 3 X, --PO 3 X 3 , ##STR3## --OH, and ##STR4## wherein X represents a hydrogen atom or a metal and R 1 , R 2 and R 3 which may be the same or different, each represents a hydrogen atom or an alkyl group having 1 to 18 carbon atoms.
Claim 6
Dependent Claim
29 words
The method of claim 1, wherein the lubricating agent in the lower magnetic layer is selected from the group consisting of fatty acids, phosphoric acid esters and metallic soaps.
Claim 7
Dependent Claim
17 words
The method of claim 1, wherein the curing agent in the lower magnetic layer is a polyisocyanate.
Claim 8
Dependent Claim
18 words
The method of claim 1, wherein the thickness of the upper magnetic layer is 0.05 to 1 μm.
Claim 9
Dependent Claim
18 words
The method of claim 1, wherein the thickness of the lower magnetic layer is 2 to 5 μm.
Claim 10
Dependent Claim
19 words
The method of claim 1, wherein the coercive force of the upper magnetic layer is 1,000 to 2,500 Oe.
Claim 11
Dependent Claim
30 words
The method claim 1, wherein the coercive force of the lower magnetic layer is less than the coercive force of the upper magnetic layer and is 710 to 1,500 Oe.
Claim 12
Dependent Claim
22 words
The method of claim 1, wherein the heat treatment is carried out at 50° to 100° C. for 1 to 72 hours.
References Cited (Backward Citations)
No citation records indexed.
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