# US 4,391,864 A · Magnetic recording medium

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- Number: US 4,391,864 A
- Document ID: US4391864A
- Status: Granted
- Kind: A
- Application number: 06/214,677
- Filed: 1980-12-09
- Granted: 1983-07-05
- Earliest claimed: 1980-03-21
- Assignees: TDK Electronics Co., Ltd.
- Inventors: Akihiko Hosaka; Kiyotaka Okuyama; Yukihiro Isobe
- Web page: https://patentgrep.com/patent/US4391864A

## CPC

- G11B 5/7022: {containing mixtures of polyurethanes or polyisocyanates with other polymers}
- Y10S 428/90: Magnetic feature
- Y10T 428/31511: Of epoxy ether
- Y10T 428/31609: Particulate metal or metal compound-containing
- 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 tape or disc which has excellent total characteristics of an adhesive strength, a repeat running durability, an electromagnetic characteristic, a gloss degree of the surface and a curling is provided. A binder of a magnetic layer comprises 40 to 70 wt. % of a urethane resin, 15 to 40 wt. % of an epoxy resin and 10 to 40 wt. % of a phenoxy resin.

## Claims

### Claim 1

A magnetic recording medium having a substrate coated with a magnetic layer which comprises a binder and a magnetic powder, said binder in the magnetic layer comprising 40 to 70 wt. % of a urethane resin, 15 to 40 wt. % of a thermosetting epoxy resin characterized by its content of epoxide groups, and 10 to 40 wt. % of a thermoplastic phenoxy resin characterized by its content of polyhydroxyether groups.

### Claim 2 (depends on 1)

A magnetic recording medium according to claim 1 which is a magnetic recording tape.

### Claim 3 (depends on 1)

A magnetic recording medium according to claim 1 which is a magnetic recording disc.

### Claim 4 (depends on 1)

A magnetic recording medium according to claim 1 wherein a curing agent is incorporated at a ratio of 8 to 20 wt. parts based on 100 wt. parts of the binder.

### Claim 5 (depends on 4)

A magnetic recording medium according to claim 4 wherein the curing agent is a polyisocyanate.