Magnetic recording medium
A magnetic recording medium with excellent high density recording performances and good durability comprising a non-magnetic substrate, a non-magnetic layer containing a non-magnetic powder and a binder formed on the non-magnetic substrate, and a magnetic layer having a thickness of less than 100 nm and containing a substantially particulate non-magnetic powder, a substantially particulate magnetic powder having an average particle size of less than 25 nm, and a binder, wherein an average particle size R of the non-magnetic powder contained in the magnetic layer and a thickness D of the magnetic powder satisfy the following relationship: 0.88≦R/D≦2.5.
1. A magnetic recording medium, comprising:
a non-magnetic substrate,
a non-magnetic layer containing a non-magnetic powder and a binder formed on the non-magnetic substrate, and
a magnetic layer having a thickness of less than 100 nm and containing a substantially particulate non-magnetic powder, a substantially particulate magnetic powder having an acicular ratio of less than 2 and an average particle size of less than 25 nm, and a binder,
wherein an average particle size R of the non-magnetic powder contained in the magnetic layer and a thickness D of the magnetic layer satisfy the following relationship:
0.885 ≦R/D≦ 2.5.
2. The magnetic recording medium according to claim 1 , wherein the non-magnetic powder contained in the magnetic layer has an average particle size of less than 200 nm.
3. The magnetic recording medium according to claim 1 , wherein the non-magnetic powder contained in the magnetic layer has a Moh's hardness of at least 6.
4. The magnetic recording medium according to claim 1 , wherein the non-magnetic powder contained in the magnetic layer is at least one non-magnetic powder selected from the group of α-alumina, β-alumina, silicon carbide, chromium oxide, cerium oxide, α-iron oxide, corundum, artificial diamond, silicon nitride, silicon carbide, titanium carbide, titanium oxide, silicon dioxide and boron nitride.
5. The magnetic recording medium according to claim 1 , wherein the magnetic layer further comprises carbon black.
6. The magnetic recording medium according to claim 1 , wherein an axis ratio of a longer axis to a shorter axis of a single particle of said non-magnetic powder is less than 3.