# US 4,391,874 A · Magnetic recording medium

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- Number: US 4,391,874 A
- Document ID: US4391874A
- Status: Granted
- Kind: A
- Application number: 06/350,510
- Filed: 1982-02-19
- Granted: 1983-07-05
- Earliest claimed: 1981-02-19
- Assignees: Fuji Photo Film Co., Ltd.
- Inventors: Nobuyuki Yamamoto; Kyoichi Naruo; Tsutomu Okita
- Web page: https://patentgrep.com/patent/US4391874A

## CPC

- G11B 5/725: containing a lubricant {, e.g. organic compounds (inorganic carbon protective coating G11B5/727)}
- Y10S 428/90: Magnetic feature
- Y10T 428/265: 1 mil or less
- Y10T 428/31678: Of metal
- G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R)
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A magnetic recording medium having a thin magnetic film on a non-magnetic support base is disclosed. A layer of isocyanic acid ester is formed in connection with the medium, and may be formed on either the surface of the metal film or the surface of the base opposite the metal film or both. The resulting medium has excellent running properties, wear resistance and electro-to-magnetic conversion characteristics which are maintained after repeated use.

## Claims

### Claim 1

A magnetic recording medium, comprising:
a non-magnetic support base;
a thin magnetic metal film formed on a surface of said non-magnetic support base; and
a layer of an isocyanic acid ester having the formula RN.dbd.C.dbd.O, wherein R is an alkyl group.

### Claim 2 (depends on 1)

A magnetic recording medium as claimed in claim 1, wherein said layer of isocyanic acid ester is formed on an outer surface of said thin magnetic metal film.

### Claim 3 (depends on 1, 2)

A magnetic recording medium as claimed in any of claims 1 or 2, wherein said layer of isocyanic acid ester is formed on a surface of said non-magnetic support base opposite to said surface on which said thin magnetic metal film is formed.

### Claim 4 (depends on 1)

A magnetic recording medium as claimed in claim 1, wherein said thin magnetic metal film has a thickness within the range of 0.05 to 2 .mu.m.

### Claim 5 (depends on 4)

A magnetic recording medium as claimed in claim 4, wherein said thickness is within the range of 0.1 to 0.4 .mu.m.

### Claim 6 (depends on 1)

A magnetic recording medium as claimed in claim 1, wherein said alkyl group is a straight chain alkyl group having 8 or more carbon atoms.

### Claim 7 (depends on 6)

A magnetic recording medium as claimed in claim 6, wherein said isocyanic acid ester is selected from the group consisting of octyl isocyanate, decyl isocyanate, dodecyl isocyanate and octadecyl isocyanate.

### Claim 8 (depends on 1)

A magnetic recording medium as claimed in claim 1, wherein said layer of isocyanic acid ester has a dry weight within the range of 1 to 50 mg/m.sup.2.

### Claim 9 (depends on 8)

A magnetic recording medium as claimed in claim 8, wherein said dry weight is within the range of from 2 to 10 mg/m.sup.2.

### Claim 10 (depends on 8)

A magnetic recording medium as claimed in claim 8, wherein said alkyl group of the isocyanic acid ester is a straight chain alkyl group having 8 to 18 carbon atoms.

### Claim 11 (depends on 10)

A magnetic recording medium as claimed in claim 10, wherein said isocyanic acid ester is selected from the group consisting of octyl isocyanate, decyl isocyanate, dodecyl isocyanate and octadecyl isocyanate.

### Claim 12 (depends on 11)

A magnetic recording medium as claimed in claim 11, wherein said thin magnetic metal film is composed of a ferromagnetic metal or alloy selected from the group consisting of Fe, Co, Ni, Fe-Co, Fe-Ni, Co-Ni, Fe-Si, Fe-Rh, Co-P, Co-B, Co-Si, Co-V, Co-Y, Co-La, Co-Ce, Co-Pr, Co-Sm, Co-Pt, Co-Mn, Fe-Co-Ni, Co-Ni-P, Co-Ni-B, Co-Ni-Ag, Co-Ni,Na, Co-Ni-Ce, Co-Ni-Zn, Co-Ni-Cu, Co-Ni-W, Co-Ni-Re and Co-Sm-Cu.