Magnetic recording medium

Abstract

A magnetic recording medium is provided that comprises a non-magnetic support and, in order thereabove, a radiation-cured layer cured by exposing a layer comprising a radiation curing compound to radiation, and a magnetic layer comprising a ferromagnetic powder dispersed in a binder, the radiation curing compound having a radiation curing functional group concentration of at least 2 mmol/g but no greater than 6 mmol/g, and the radiation-cured layer comprising at least 30 vol % but no greater than 60 vol % of an inorganic powder.

Description

Claims

1. A magnetic recording medium comprising: a non-magnetic support and, in order thereabove;a radiation-cured layer cured by exposing a layer comprising a radiation curing compound to radiation; anda magnetic layer comprising a ferromagnetic powder dispersed in a binder,the radiation curing compound having a radiation curing functional group concentration of at least 2 mmol/g but no greater than 6 mmol/g, andthe radiation-cured layer comprising at least 30 vol % but no greater than 60 vol % of an inorganic powder.

2. The magnetic recording medium according to claim 1, wherein the magnetic recording medium comprises, between the radiation-cured layer and the magnetic layer, a non-magnetic layer comprising a non-magnetic powder dispersed in a biinder.

3. The magnetic recording medium according to claim 1, wherein the radiation curing compound comprises a urethane (meth)acrylate that does not have a cyclic structure.

4. The magnetic recording medium according to claim 1, wherein the inorganic powder is spherical particles having an average particle size of 5 to 50 nm.

5. The magnetic recording medium according to claim 1, wherein the ferromagnetic powder is an acicular ferromagnetic substance having a major axis length of 20 to 50 nm, a tabular magnetic substance having a plate size of 10 to 50 nm, or a spherical or ellipsoidal magnetic substance having a diameter of 10 to 50 nm.

6. The magnetic recording medium according to claim 1, wherein the radiation curing compound has a molecular weight of 200 to 1,000.

7. The magnetic recording medium according to claim 1, wherein the inorganic powder comprises at least one selected from the group consisting of silicon dioxide, α-iron oxide, and titanium dioxide.

8. The magnetic recording medium according to claim 1, wherein the radiation-cured layer has a thickness of 0.1 to 1.0 μm.

9. The magnetic recording medium according to claim 1, wherein the magnetic layer has a thickness of 0.1 to 1.0 μm.

10. The magnetic recording medium according to claim 1, wherein the non-magnetic support has a thickness of 3 to 80 μm.

11. The magnetic recording medium according to claim 2, wherein the radiation curing compound comprises a urethane (meth)acrylate that does not have a cyclic structure.

12. The magnetic recording medium according to claim 2, wherein the inorganic powder is spherical particles having an average particle size of 5 to 50 nm.

13. The magnetic recording medium according to claim 2, wherein the ferromagnetic powder is an acicular ferromagnetic substance having a major axis length of 20 to 50 nm, a tabular magnetic substance having a plate size of 10 to 50 nm, or a spherical or ellipsoidal magnetic substance having a diameter of 10 to 50 nm.

14. The magnetic recording medium according to claim 2, wherein the radiation curing compound has a molecular weight of 200 to 1,000.

15. The magnetic recording medium according to claim 2, wherein the inorganic powder comprises at least one selected from the group consisting of silicon dioxide, α-iron oxide, and titanium dioxide.

16. The magnetic recording medium according to claim 2, wherein the radiation-cured layer has a thickness of 0.1 to 1.0 μm.

17. The magnetic recording medium according to claim 2, wherein the magnetic layer has a thickness of 0.1 to 1.0 μm.

18. The magnetic recording medium according to claim 2, wherein the non-magnetic support has a thickness of 3 to 80 μm.

19. The magnetic recording medium according to claim 2, wherein the non-magnetic layer has a thickness of 0.2 to 3.0 μm.

20. The magnetic recording medium according to claim 2, wherein the non-magnetic powder is α-iron oxide or titanium oxide.