Magnetic recording medium and method for production thereof

• US 20070224456A1
• Filed: 03/27/2007
• Published: 09/27/2007
• Est. Priority Date: 03/27/2006
• Status: Abandoned Application

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Inventors: Murao, Naoto, Aritoshi, Youhei
• Application Number:
  US11/727,534
• Publication Number:
  US 20070224456A1
• Time in Patent Office: Days
• US Class Current: 428/840.200
• CPC Class Codes: G11B 5/70 on a base layer
• 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

Abstract

A magnetic recording medium including: a nonmagnetic support; a smoothing layer containing a polymer; a nonmagnetic layer formed by coating a first solution containing nonmagnetic powder and a binder on the smoothing layer and drying the coated first solution; and a magnetic layer formed by coating a second solution containing ferromagnetic powder, inorganic powder and a binder on the nonmagnetic layer and drying the coated second solution, in this order.

Claims

1. A magnetic recording medium comprising:

a nonmagnetic support;

a smoothing layer containing a polymer;

a nonmagnetic layer formed by coating a first solution containing nonmagnetic powder and a binder on the smoothing layer and drying the coated first solution; and

a magnetic layer formed by coating a second solution containing ferromagnetic powder, inorganic powder and a binder on the nonmagnetic layer and drying the coated second solution, in this order.

2. The magnetic recording medium as claimed in claim 1, wherein an average particle size of the inorganic powder contained in the magnetic layer is no less than a thickness of the magnetic layer.

3. The magnetic recording medium as claimed in claim 1, wherein the magnetic layer has a thickness of not more than 0.15 μ

m.

4. The magnetic recording medium as claimed in claim 2, wherein the magnetic layer has a thickness of not more than 0.15 μ

m.

5. The magnetic recording medium as claimed in claim 1, wherein the magnetic layer has a thickness of from 0.01 to 0.10 μ

m.

6. The magnetic recording medium as claimed in claim 2, wherein the magnetic layer has a thickness of from 0.01 to 0.10 μ

m.

7. The magnetic recording medium as claimed in claim 1, wherein the smoothing layer has a Young'"'"'s modulus of from 10 to 90% of a Young'"'"'s modulus of the nonmagnetic support.

8. The magnetic recording medium as claimed in claim 2, wherein the smoothing layer has a Young'"'"'s modulus of from 10 to 90% of a Young'"'"'s modulus of the nonmagnetic support.

9. The magnetic recording medium as claimed in claim 1, wherein the smoothing layer has a Young'"'"'s modulus of from 1 to 8 Gpa.

10. The magnetic recording medium as claimed in claim 2, wherein the smoothing layer has a Young'"'"'s modulus of from 1 to 8 Gpa.

11. The magnetic recording medium as claimed in claim 1, wherein a number of the inorganic powder protruded through a surface of the magnetic layer is from 50 to 200/100 μ

m².

12. The magnetic recording medium as claimed in claim 2, wherein a number of the inorganic powder protruded through a surface of the magnetic layer is from 50 to 200/100 μ

m².

13. The magnetic recording medium as claimed in claim 1, wherein the magnetic layer has a centerline average surface roughness of from 1.5 to 3.0 nm.

14. The magnetic recording medium as claimed in claim 2, wherein the magnetic layer has a centerline average surface roughness of from 1.5 to 3.0 nm.

15. The magnetic recording medium as claimed in claim 1, wherein the smoothing layer has a thickness of from 0.05 to 1.5 μ

m.

16. The magnetic recording medium as claimed in claim 2, wherein the smoothing layer has a thickness of from 0.05 to 1.5 μ

m.

17. The magnetic recording medium as claimed in claim 1, wherein the nonmagnetic support has a thickness of from 3 to 80 μ

m.

18. The magnetic recording medium as claimed in claim 2, wherein the nonmagnetic support has a thickness of from 3 to 80 μ

m.

19. A method for producing a magnetic recording medium, comprising:

coating a first solution on a nonmagnetic support and drying the coated first solution to form a smoothing layer containing a polymer;

coating a second solution containing nonmagnetic powder and a binder on the smoothing layer and drying the coated second solution to form a nonmagnetic layer; and

coating a third solution containing ferromagnetic powder, inorganic powder and a binder on the nonmagnetic layer and drying the coated third solution to form a magnetic layer,

in this order.