Claims
- 1. A magnetic disc cartridge for high density recording of 35 Kfci or more comprising in combination a cartridge case, a magnetic disc housed rotatably in said cartridge case, and a cleaning sheet of non-woven fabric secured on an inner surface of said cartridge case juxtapositioned relative to said magnetic disc, said magnetic disc having a linear recording density of 35 Kfci or more including a magnetic layer comprising a soft magnetic powder and a reinforcing powder dispersed in a binder resin, said soft magnetic powder being selected from at least one member of the group consisting of a ferromagnetic metal powder and a barium ferrite powder, said reinforcing powder having a particle size of from 0.1 to 1.0 .mu.m and being present in said magnetic layer of said magnetic disc in an amount of from 5 to 40% by weight, wherein at least a disc side surface layer of said cleaning sheet, which is brought into direct sliding contact with said magnetic layer consists of a non-thermoplastic fiber.
- 2. A magnetic disc cartridge according to claim 1, wherein said reinforcing powder is aluminum oxide powder.
- 3. A magnetic disc cartridge according to claim 1, wherein said magnetic disc has a surface roughness (Ra) of not more than 0.01 .mu.m.
- 4. A magnetic disc cartridge according to claim 1, wherein said at least one fatty acid ester is 2-heptylundecyl oleate.
- 5. A magnetic disc cartridge according to claim 1, wherein said magnetic disc has a track density of at least 150 TPI.
- 6. The magnetic disc cartridge according to claim 1, wherein said magnetic layer of said magnetic disc further includes at least one fatty acid ester lubricant having a melting point of 0.degree. C. or lower.
- 7. The magnetic disc cartridge according to claim 1, wherein said non-thermoplastic fiber is rayon.
- 8. A magnetic disc cartridge according to claim 7, wherein said cleaning sheet of non-woven fabric consists of three layers, a surface layer and a backside layer each consisting of rayon fibers and an intermediate layer comprising a mixture of rayon fibers and thermoplastic fibers.
- 9. A magnetic disc cartridge according to claim 1, wherein said binder resin of said magnetic layer comprises urethane.
- 10. A magnetic disc cartridge according to claim 1, wherein said soft magnetic powder present in said magnetic layer is a ferromagnetic metal powder.
- 11. A magnetic disc cartridge according to claim 10, wherein said ferromagnetic metal powder is iron powder.
- 12. A magnetic disc cartridge according to claim 1, wherein said soft magnetic powder present in said magnetic layer is barium ferrite powder.
Priority Claims (3)
Number |
Date |
Country |
Kind |
63-173724 |
Jul 1988 |
JPX |
|
63-219240 |
Sep 1988 |
JPX |
|
63-240511 |
Sep 1988 |
JPX |
|
Parent Case Info
This application is a continuation of Ser. No. 08/068,290 filed May 28, 1993, which is a continuation of Ser. No. 07/784,071 filed Oct. 30, 1991, which is a continuation of Ser. No. 07/378,826 filed Jul. 12, 1989.
US Referenced Citations (23)
Foreign Referenced Citations (11)
Number |
Date |
Country |
0194649 |
Mar 1986 |
EPX |
0238068 |
Mar 1987 |
EPX |
0243185 |
Apr 1987 |
EPX |
0244868 |
May 1987 |
EPX |
2287744 |
Oct 1975 |
FRX |
53-102727 |
Sep 1978 |
JPX |
54-124707 |
Sep 1979 |
JPX |
55-285602 |
Feb 1980 |
JPX |
57-7087 |
May 1982 |
JPX |
62-78717 |
Apr 1987 |
JPX |
2100048 |
Dec 1982 |
GBX |
Non-Patent Literature Citations (1)
Entry |
IBM Technical Disclosure Bulletin; vol. 25, #7B; Olson et al., Dec. 1982. |
Continuations (3)
|
Number |
Date |
Country |
Parent |
68290 |
May 1993 |
|
Parent |
784071 |
Oct 1991 |
|
Parent |
378826 |
Jul 1989 |
|