Magnetic recording medium

• US 20070020490A1
• Filed: 07/20/2006
• Published: 01/25/2007
• Est. Priority Date: 07/20/2005
• Status: Abandoned Application

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Harasawa, Takeshi, Oyanagi, Masahito
• Application Number:
  US11/489,534
• Publication Number:
  US 20070020490A1
• Time in Patent Office: Days
• US Class Current: 428/842.800
• CPC Class Codes: G11B 5/7026 Radiation curable polymers
• CPC Class Codes: G11B 5/70605 metals or alloys
• CPC Class Codes: G11B 5/70678 Ferrites
• CPC Class Codes: G11B 5/7085 non-magnetic abrasive particles
• CPC Class Codes: G11B 5/714 characterised by the dimension of the magnetic particles
• CPC Class Codes: G11B 5/73 Base layers , i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
• CPC Class Codes: G11B 5/733 characterised by the addition of non-magnetic particles base layers having a non-magnetic layer under a soft magnetic layer G11B5/736; magnetic recording media substrates G11B5/739
• CPC Class Codes: G11B 5/82 Disk carriers

Abstract

Provided is a magnetic recording medium for high-density recording, that has excellent electromagnetic characteristics, error rates, and durability. The magnetic recording medium comprises a magnetic layer comprising a ferromagnetic powder, a binder and an abrasive on a nonmagnetic support and is employed for recording a magnetic signal on the medium and reproducing the recorded signal with a reproduction head. The abrasive has a Vickers hardness ranging from 18 to 80 GPa and a mean particle diameter ranging from 10 to 100 nm. The magnetic layer comprises the abrasive in a quantity of 5 to 60 weight parts per 100 weight parts of the ferromagnetic powder and has a thickness ranging from 10 to 100 nm. The number of abrasive present on the surface of the magnetic layer ranges from 0.01 to 1 per {(minimum bit length of the recorded signal)×(read track width of the reproduction head)} micrometer².

Claims

1. A magnetic recording medium comprising a magnetic layer comprising a ferromagnetic powder, a binder and an abrasive on a nonmagnetic support, wherein

said magnetic recording medium is employed for recording a magnetic signal on the medium and reproducing the recorded signal with a reproduction head,

said abrasive has a Vickers hardness ranging from 18 to 80 GPa and a mean particle diameter ranging from 10 to 100 nm,

said magnetic layer comprises said abrasive in a quantity of 5 to 60 weight parts per 100 weight parts of the ferromagnetic powder,

said magnetic layer has a thickness ranging from 10 to 100 nm, and

the number of abrasive present on the surface of said magnetic layer ranges from 0.01 to 1 per {(minimum bit length of the recorded signal)×

(read track width of the reproduction head)} micrometer².

2. The magnetic recording medium according to claim 1, wherein said abrasive has a mean particle diameter of not greater than twice the minimum bit length of said recorded signal.

3. The magnetic recording medium according to claim 1, wherein said magnetic layer has a surface roughness Ra of equal to or less than 2.0 nm.

4. The magnetic recording medium according to claim 1, wherein said ferromagnetic powder is a hexagonal ferrite powder having a mean plate diameter ranging from 10 to 40 nm or a ferromagnetic metal powder having a mean major axis length ranging from 25 to 100 nm.

5. The magnetic recording medium according to claim 1, wherein the minimum bit length of said recorded signal is equal to or less than 100 nm.

6. The magnetic recording medium according to claim 1, wherein the read track width of said reproduction head is equal to or less than 2500 nm.

7. The magnetic recording medium according to claim 1, which further comprises an intermediate layer comprising a principal component in the form of a radiation-curing resin between the nonmagnetic support and the magnetic layer.

8. The magnetic recording medium according to claim 1, which further comprises a nonmagnetic layer comprising a nonmagnetic powder and a binder between the nonmagnetic support and the magnetic layer.

9. The magnetic recording medium according to claim 8, which further comprises an intermediate layer comprising a principal component in the form of a radiation-curing resin between the nonmagnetic support and the nonmagnetic layer or the nonmagnetic layer and the magnetic layer.

10. A method of recording a magnetic signal on a magnetic recording medium and reproducing the recorded signal with a reproduction head, wherein

said magnetic recording medium comprises a magnetic layer comprising a ferromagnetic powder, a binder and an abrasive on a nonmagnetic support,

said abrasive has a Vickers hardness ranging from 18 to 80 GPa and a mean particle diameter ranging from 10 to 100 nm,

said magnetic layer comprises said abrasive in a quantity of 5 to 60 weight parts per 100 weight parts of the ferromagnetic powder,

said magnetic layer has a thickness ranging from 10 to 100 nm, and

the number of abrasive present on the surface of said magnetic layer ranges from 0.01 to 1 per {(minimum bit length of the recorded signal)×

(read track width of the reproduction head)} micrometer².

11. The method according to claim 10, wherein said abrasive has a mean particle diameter of not greater than twice the minimum bit length of said recorded signal.

12. The method according to claim 10, wherein said magnetic layer has a surface roughness Ra of equal to or less than 2.0 nm.

13. The method according to claim 10, wherein said ferromagnetic powder is a hexagonal ferrite powder having a mean plate diameter ranging from 10 to 40 nm or a ferromagnetic metal powder having a mean major axis length ranging from 25 to 100 nm.

14. The method according to claim 10, wherein the minimum bit length of said recorded signal is equal to or less than 100 nm.

15. The method according to claim 10, wherein the read track width of said reproduction head is equal to or less than 2500 nm.

16. The method according to claim 10, wherein said magnetic recording medium further comprises an intermediate layer comprising a principal component in the form of a radiation-curing resin between the nonmagnetic support and the magnetic layer.

17. The method according to claim 10, wherein said magnetic recording medium further comprises a nonmagnetic layer comprising a nonmagnetic powder and a binder between the nonmagnetic support and the magnetic layer.

18. The method according to claim 17, wherein said magnetic recording medium further comprises an intermediate layer comprising a principal component in the form of a radiation-curing resin between the nonmagnetic support and the nonmagnetic layer or the nonmagnetic layer and the magnetic layer.

19. An apparatus comprising a recording head, a magnetic recording medium and a reproduction head, wherein

said recording head records a magnetic signal on said magnetic recording medium and said reproduction head reproduces the recorded signal,

said magnetic recording medium comprises a magnetic layer comprising a ferromagnetic powder, a binder and an abrasive on a nonmagnetic support,

said abrasive has a Vickers hardness ranging from 18 to 80 GPa and a mean particle diameter ranging from 10 to 100 nm,

said magnetic layer comprises said abrasive in a quantity of 5 to 60 weight parts per 100 weight parts of the ferromagnetic powder,

said magnetic layer has a thickness ranging from 10 to 100 nm, and

the number of abrasive present on the surface of said magnetic layer ranges from 0.01 to 1 per {(minimum bit length of the recorded signal)×

(read track width of the reproduction head)} micrometer².

20. The apparatus according to claim 19, wherein said abrasive has a mean particle diameter of not greater than twice the minimum bit length of said recorded signal.

21. The apparatus according to claim 19, wherein said magnetic layer has a surface roughness Ra of equal to or less than 2.0 nm.

22. The apparatus according to claim 19, wherein said ferromagnetic powder is a hexagonal ferrite powder having a mean plate diameter ranging from 10 to 40 nm or a ferromagnetic metal powder having a mean major axis length ranging from 25 to 100 nm.

23. The apparatus according to claim 19, wherein the minimum bit length of said recorded signal is equal to or less than 100 nm.

24. The apparatus according to claim 19, wherein the read track width of said reproduction head is equal to or less than 2500 nm.

25. The apparatus according to claim 19, wherein said magnetic recording medium further comprises an intermediate layer comprising a principal component in the form of a radiation-curing resin between the nonmagnetic support and the magnetic layer.

26. The apparatus according to claim 19, wherein said magnetic recording medium further comprises a nonmagnetic layer comprising a nonmagnetic powder and a binder between the nonmagnetic support and the magnetic layer.

27. The apparatus according to claim 26, wherein said magnetic recording medium further comprises an intermediate layer comprising a principal component in the form of a radiation-curing resin between the nonmagnetic support and the nonmagnetic layer or the nonmagnetic layer and the magnetic layer.