Magnetic recording medium
A magnetic recording medium comprising: a nonmagnetic support having a first surface and a second surface; and a magnetic layer containing ferromagnetic powder and a binder, so that the magnetic layer, the first surface and the second surface are in this order, wherein the nonmagnetic support contains polyester, a difference between largest ratio and smallest ratio among peak intensity ratios of gauche/trans on the first and second surfaces of the support in a machine direction and a transverse direction obtained by ATR-FT-IR method is 0.030 or less in an absolute value, and a shrinkage factor of the magnetic recording medium after preservation at 70° C. 5% RH for one week is 0.040% or less.
1 . A magnetic recording medium comprising:
a nonmagnetic support having a first surface and a second surface; and
a magnetic layer containing ferromagnetic powder and a binder, so that the magnetic layer, the first surface and the second surface are in this order,
wherein the nonmagnetic support contains polyester, a difference between largest ratio and smallest ratio among peak intensity ratios of gauche/trans on the first and second surfaces of the support in a machine direction and a transverse direction obtained by ATR-FT-IR method is 0.030 or less in an absolute value, and a shrinkage factor of the magnetic recording medium after preservation at 70° C. 5% RH for one week is 0.040% or less.
2 . The magnetic recording medium according to claim 1 , further comprising a substantially nonmagnetic lower layer between the nonmagnetic support and the magnetic layer.
3 . The magnetic recording medium according to claim 1 , wherein the substantially nonmagnetic lower layer contains a binder and nonmagnetic powder.
4 . The magnetic recording medium according to claim 1 , wherein the difference between largest ratio and smallest ratio among peak intensity ratios of gauche/trans on the first and second surfaces of the support in a machine direction and a transverse direction obtained by ATR-FT-IR method is 0.02 or less in an absolute value.
5 . The magnetic recording medium according to claim 1 , wherein the difference between largest ratio and smallest ratio among peak intensity ratios of gauche/trans on the first and second surfaces of the support in a machine direction and a transverse direction obtained by ATR-FT-IR method is 0.016 or less in an absolute value.
6 . The magnetic recording medium according to claim 4 , wherein the support contains polyethylene naphthalate.
7 . The magnetic recording medium according to claim 5 , wherein the support contains polyethylene naphthalate.
8 . The magnetic recording medium according to claim 1 , wherein the nonmagnetic support further contains a filler.
9 . The magnetic recording medium according to claim 1 , wherein the nonmagnetic support has a thickness of from 10 to 100 μm.
10 . The magnetic recording medium according to claim 1 , wherein the nonmagnetic support has a thickness of from 20 to 80 μm.
11 . The magnetic recording medium according to claim 1 , wherein the nonmagnetic support has a central line average surface roughness of 8 nm or less.
12 . The magnetic recording medium according to claim 1 , wherein the nonmagnetic support has a central line average surface roughness of 6 nm or less.