Magnetic recording medium

Abstract

A magnetic recording medium including a nonmagnetic support and a magnetic layer containing ferromagnetic powder and a binder, wherein the magnetic layer contains diamond particles having an average particle size of from 20 to 100 nm, a volume per a particle of the ferromagnetic powder is from 100 to 8,000 nm3, and the support has an intrinsic viscosity of from 0.40 to 0.60 dl/g and is substantially free from particles.

Description

Claims

1. A magnetic recording medium comprising: a nonmagnetic support; and a magnetic layer containing ferromagnetic powder and a binder, wherein the magnetic layer contains diamond particles having an average particle size of from 20 to 100 nm, a volume per a particle of the ferromagnetic powder is from 100 to 8,000 nm3, and the support has an intrinsic viscosity of from 0.40 to 0.60 dl/g and is substantially free from particles.

2. The magnetic recording medium according to claim 1, wherein the diamond particles have an average particle size of from 30 to 90 nm.

3. The magnetic recording medium according to claim 1, wherein the diamond particles have an average particle size of from 40 to 80 nm.

4. The magnetic recording medium according to claim 1, wherein the magnetic layer contains the diamond particles in an amount of from 1 to 5 weight % based on an amount of the ferromagnetic powder contained in the magnetic layer.

5. The magnetic recording medium according to claim 1, wherein the magnetic layer contains the diamond particles in an amount of from 2 to 4 weight % based on an amount of the ferromagnetic powder contained in the magnetic layer.

6. The magnetic recording medium according to claim 1, wherein the support has an intrinsic viscosity of from 0.46 to 0.56 dl/g.

7. The magnetic recording medium according to claim 1, further comprising a nonmagnetic layer containing a binder and nonmagnetic powder, so that the nonmagnetic support, the nonmagnetic layer and the magnetic layer are provided in this order.

8. The magnetic recording medium according to claim 1, further comprising a backing layer containing carbon black and inorganic powder, so that the backing layer, the nonmagnetic support and the magnetic layer are provided in this order.

9. The magnetic recording medium according to claim 8, wherein the backing layer has a thickness of 0.9 μm or less.

10. The magnetic recording medium according to claim 1, wherein the ferromagnetic powder is ferromagnetic metal powder.

11. The magnetic recording medium according to claim 10, wherein the ferromagnetic metal powder has a coercive force of from 159.2 to 278.5 kA/m.

12. The magnetic recording medium according to claim 10, wherein the ferromagnetic metal powder has a coercive force of from 167.1 to 238.7 kA/m.

13. The magnetic recording medium according to claim 10, wherein the ferromagnetic metal powder has a saturation magnetization of from 90 to 140 A·m2/kg.

14. The magnetic recording medium according to claim 1, wherein the ferromagnetic powder is hexagonal ferrite powder.

15. The magnetic recording medium according to claim 14, wherein the hexagonal ferrite powder has a coercive force of from 143.3 to 318.5 kA/m.

16. The magnetic recording medium according to claim 14, wherein the hexagonal ferrite powder has a coercive force of from 159.2 to 238.9 kA/m.

17. The magnetic recording medium according to claim 14, wherein the hexagonal ferrite powder has a coercive force of from 191.0 to 214.9 kA/m.

18. The magnetic recording medium according to claim 14, wherein the hexagonal ferrite powder has a saturation magnetization of from 30 to 80 A·m2/kg.

19. The magnetic recording medium according to claim 1, wherein the ferromagnetic powder is iron nitride powder.

20. The magnetic recording medium according to claim 19, wherein the iron nitride powder has a coercive force of from 79.6 to 318.4 kA/m.

21. The magnetic recording medium according to claim 19, wherein the iron nitride powder has a saturation magnetization of from 80 to 160 Am2/kg.