Magnetic recording medium
View Patent ↗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 in the molecule and being derived from a diisocyanate that has a branched structure but does not have a cyclic structure.
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; and
a magnetic layer comprising a ferromagnetic powder dispersed in a binder,
the radiation curing compound having a radiation curing functional group in the molecule and being derived from a diisocyanate that has a branched structure but does not have a cyclic structure.
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 binder.
3. The magnetic recording medium according to claim 1 , wherein the diisocyanate having a branched structure but not having a cyclic structure is trimethylhexamethylene diisocyanate.
4. The magnetic recording medium according to claim 1 , wherein the ferromagnetic powder is an acicular ferromagnetic powder having a major axis length of 20 to 70 nm or a tabular ferromagnetic powder having a plate size of 10 to 50 nm.
5. The magnetic recording medium according to claim 1 , wherein the diisocyanate having a branched structure but not having a cyclic structure is lysine diisocyanate methyl ester.
6. The magnetic recording medium according to claim 1 , wherein the radiation curing compound is a compound obtained by reacting the diisocyanate having a branched structure but not having a cyclic structure with a compound having in the molecule a group that reacts with an isocyanate group and a radiation curing functional group.
7. The magnetic recording medium according to claim 1 , wherein the radiation curing compound is a compound obtained by reacting, with a terminal isocyanate group urethane prepolymer obtained by reacting the diisocyanate having a branched structure but not having a cyclic structure with a diol, a compound having in the molecule a hydroxyl group and a radiation curing functional group.
8. The magnetic recording medium according to claim 1 , wherein the radiation curing compound is a compound obtained by reacting, with a terminal hydroxyl group urethane prepolymer obtained by reacting the diisocyanate having a branched structure but not having a cyclic structure with a diol, a compound having in the molecule an isocyanate group and a radiation curing functional group.
9. The magnetic recording medium according to claim 1 , wherein the radiation curing functional group is an acryloyl group.
10. The magnetic recording medium according to claim 1 , wherein the number of radiation curing functional groups is 2 to 6 per molecule.
11. The magnetic recording medium according to claim 1 , wherein the radiation-cured layer has a thickness of 0.1 to 1.0 μm.
12. The magnetic recording medium according to claim 1 , wherein the magnetic layer has a thickness of 0.01 to 0.12 μm.
13. The magnetic recording medium according to claim 2 , wherein the non-magnetic layer has a thickness of 0.2 to 3.0 μm.