Magnetic recording medium and manufacturing method thereof
A magnetic recording medium in which a magnetic layer is formed on a support, wherein the magnetic layer contains a CuAu-type or Cu 3 Au-type ferromagnetic ordered alloy, and a value (Mr·t ave (G·μm)) obtained by multiplying the residual magnetic flux density (Mr (G)) with an average thickness (t ave (μm)) of the magnetic layer is 30 or more, and a method of manufacturing the magnetic recording medium, wherein a coating and drying treatment of coating a coating solution for forming a magnetic layer containing a CuAu-type or Cu 3 Au-type ferromagnetic ordered alloy on a support and of applying a drying treatment is conducted at least twice.
1 . A magnetic recording medium in which a magnetic layer is formed on a support, wherein the magnetic layer contains a CuAu-type or Cu 3 Au-type ferromagnetic ordered alloy, and a value (Mr·t ave (G·μm)) obtained by multiplying the residual magnetic flux density (Mr (G)) with an average thickness (t ave (μm)) of the magnetic layer is 30 or more.
2 . The magnetic recording medium according to claim 1 , wherein the magnetic layer comprises two or more layers.
3 . The magnetic recording medium according to claim 1 , wherein the magnetic layer contains a binder.
4 . The magnetic recording medium according to claim 3 , wherein the binder comprises a metal oxide matrix.
5 . The magnetic recording medium according to claim 3 , wherein the binder is contained by 1 to 50% by volume based on the entire volume of magnetic particles.
6 . The magnetic recording medium according to claim 1 , wherein the ferromagnetic ordered alloy is in the form of magnetic particles.
7 . The magnetic recording medium according to claim 1 , wherein the CuAu-type ferromagnetic ordered alloy is selected from the group consisting of FeNi, FePd, FePt, CoPt, and CoAu.
8 . The magnetic recording medium according to claim 1 , wherein the Cu 3 Au-type ferromagnetic ordered alloy is selected from the group consisting of Ni 3 Fe, FePd 3 , FePt 3 , CoPt 3 , Ni 3 Pt, CrPt 3 , Ni 3 Mn, and CO 3 Pt.
9 . The magnetic recording medium according to claim 1 , wherein the thickness (t) of the magnetic layer is from 40 to 100 nm.
10 . The magnetic recording medium according to claim 1 , wherein the standard deviation (σ) of the average thickness (t ave ) of the magnetic layer is 0.03 μm or less.
11 . The magnetic recording medium according to claim 1 , wherein a center line average roughness (Ra) on a surface of the magnetic recording medium is from 0.1 to 5 nm.
12 . The magnetic recording medium according to claim 1 , wherein a protective film is present on the magnetic layer.
13 . A method of manufacturing a magnetic recording medium in which a magnetic layer is formed on a support, wherein the magnetic layer contains a CuAu-type or Cu 3 Au-type ferromagnetic ordered alloy and has a value (Mr·t ave (G·μm)) obtained by multiplying the residual magnetic flux density (Mr (G)) with an average thickness (t ave (μm)) of the magnetic layer is 30 or more, and wherein
a coating and drying treatment of coating a coating solution for forming the magnetic layer containing the CuAu-type or Cu 3 Au-type ferromagnetic ordered alloy on the support and of applying a drying treatment is conducted at least twice.
14 . The method of manufacturing a magnetic recording medium according to claim 13 , wherein an annealing treatment is applied after the coating and drying treatment.
15 . The method of manufacturing a magnetic recording medium according to claim 14 , wherein the temperature of the annealing treatment is 150° C. or higher.
16 . The method of manufacturing a magnetic recording medium according to claim 13 , wherein a binder is incorporated in the coating solution.
17 . The method of manufacturing a magnetic recording medium according to claim 13 , wherein the temperature of the drying treatment is 100° C. or higher.