Magnetic recording medium

• US 6,346,310 B1
• Filed: 12/19/2000
• Issued: 02/12/2002
• Est. Priority Date: 01/21/1998
• Status: Expired due to Fees

• Current Assignee: Fujifilm Corporation (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Takano, Hiroaki, Naoe, Koji, Ishikawa, Tatsuo
• Primary Examiner(s): Resan, Stevan A.
• Application Number:
  US09/600,833
• Time in Patent Office: 420 Days
• Field of Search: 428/694.BB, 428/323, 428/328, 428/329, 428/336, 428/141, 428/425.9, 428/473.5, 428/900
• US Class Current: 428/141
• CPC Class Codes: G11B 5/7356 comprising non-magnetic particles in the back layer, e.g. particles of TiO2, ZnO or SiO2
• CPC Class Codes: G11B 5/7358 specially adapted for achieving a specific property, e.g. average roughness [Ra]
• CPC Class Codes: Y10S 428/90 Magnetic feature
• CPC Class Codes: Y10T 428/24355 Continuous and nonuniform or irregular surface on layer or component [e.g., roofing, etc.]
• CPC Class Codes: Y10T 428/25 Web or sheet containing structurally defined element or component and including a second component containing structurally defined particles
• CPC Class Codes: Y10T 428/256 Heavy metal or aluminum or compound thereof
• CPC Class Codes: Y10T 428/257 Iron oxide or aluminum oxide
• CPC Class Codes: Y10T 428/265 1 mil or less
• CPC Class Codes: Y10T 428/31609 Particulate metal or metal compound-containing
• CPC Class Codes: Y10T 428/31721 Of polyimide

Abstract

Disclosed is a magnetic recording medium comprising a magnetic layer on a surface of a flexible support and a backcoat layer on the opposite surface, characterized in that the backcoat layer comprises a granulated oxide consisting of titanium oxide, α-iron oxide or a mixture thereof and carbon black in the weight ratio ranging from 60/40 to 90/10, and further comprises a binder in an amount ranging from 10 to 40 parts by weight with respect to 100 parts by weight of the total amount of the granulated oxide and carbon black. The magnetic recording medium of the present invention is characterized in that both the running durability and electromagnetic characteristics are excellent.

Claims

1. A magnetic recording medium comprising a magnetic layer on a surface of a flexible support and a backcoat layer on the opposite surface, characterized in that the backcoat layer comprises a spherical or acicular granulated oxide consisting of titanium oxide, α

-iron oxide or a mixture thereof and carbon black in the weight ratio ranging from 60/40 to 90/10, and further comprises a binder in an amount ranging from 10 to 40 parts by weight with respect to 100 parts by weight of the total amount of the granulated oxide and carbon black, and the thickness of the backcoat layer ranges from 0.05 to 0.5 μ

m.

2. The magnetic recording medium according to claim 1, wherein said granulated oxide contained in said backcoat layer has a spherical shape and the particle diameter thereof ranges from 0.01 to 0.2 μ

m.

3. The magnetic recording medium according to claim 1, wherein said granulated oxide contained in said backcoat layer has an acicular shape, the length of the major axis thereof ranges from 0.05 to 0.3 μ

m and the length of the minor axis thereof ranges from 0.01 to 0.05 μ

m.

4. The magnetic recording medium according to any of claim 1, wherein said carbon black contained in said backcoat layer has the particle diameter ranging from 0.01 to 0.3 μ

m.

5. The magnetic recording medium according to any of claim 1, wherein said backcoat layer comprises a polyurethane resin as a binder, said polyurethane resin being a reactive product of a diol and an organic diisocyanate, said diol consisting of those containing, respectively, a short chain diol having a cyclic structure in an amount ranging from 17 to 40% by weight and a long chain diol having an ether linkage in an amount ranging from 10 to 50% by weight with respect to said polyurethane resin, wherein said ether linkage is contained in said long chain diols in an amount ranging from 1.0 to 5.0 mol/g with respect to said polyurethane resin.

6. The magnetic recording medium according to any of claim 1, wherein the thickness of said backcoat layer is within the range of from 0.1 to 0.3 μ

m.

7. The magnetic recording medium according to any of claim 1, wherein the surface roughness on the backcoat layer side of said flexible support is equal to or less than 4 nm.

8. The magnetic recording medium according to any of claim 1, wherein said flexible support is an aramid base.

9. The magnetic recording medium according to any of claim 1, wherein the adhesion strength between said backcoat layer and said flexible support is equal to or higher than 80 g/ (8 mm width).

10. The magnetic recording medium according to any of claim 1, to wherein a nonmagnetic layer containing a nonmagnetic inorganic powder and a binder is provided between said flexible support and said magnetic layer.

11. The magnetic recording medium according to any of claim 1, wherein the total thickness is within the range of from 3 to 7.5 μ

m.