Magnetic recording tape
View Patent ↗A magnetic recording tape comprising a magnetic layer, a flexible support and a back coat layer in this order, wherein the support is a polyester film having an intrinsic viscosity of from 0.40 to 0.60 dl/g and a number average molecular weight of from 12,000 to 24,000, a surface of the back coat layer has protrusions having a height of 100 nm or more measured with an atomic force microscope in a density of from 10 to 500 in 90 μm square, and a ratio of a total number of protrusions having a height of 50 nm or more on the surface of the back coat layer to a total number of protrusions having a height of 100 nm or more on the surface of the back coat layer is from 10 to 100.
1. A magnetic recording tape comprising a magnetic layer, a flexible support and a back coat layer in this order, wherein the magnetic layer is of coating type and comprises dispersion of ferromagnetic powder in a binder and wherein the support is a polyester film having an intrinsic viscosity of from 0.40 to 0.60 dl/g and a number average molecular weight of from 12,000 to 24,000, a surface of the back coat layer has protrusions having a height of 100 nm or more measured with an atomic force microscope in a density of from 10 to 500 in 90 μm square, and a ratio of a total number of protrusions having a height of 50 nm or more on the surface of the back coat layer to a total number of protrusions having a height of 100 nm or more on the surface of the back coat layer is from 10 to 100.
2. The magnetic recording tape according to claim 1 , wherein the flexible support comprises two or more layers, and a surface roughness of the support on a side having the magnetic layer is 1 nm or more and less than 6 nm, and a surface roughness of the support on a side having the back coat layer is 6 nm or more and less than 10 nm.
3. The magnetic recording tape according to claim 2 , wherein the surface roughness of the support on a side having the magnetic layer is 1.5 to 5.5 nm.
4. The magnetic recording tape according to claim 2 , wherein the surface roughness of the support on a side having the back coat layer is 6.5 to 9.0 nm.
5. The magnetic recording tape according to claim 1 , wherein the ratio is 20 to 80.
6. The magnetic recording tape according to claim 1 , wherein the polyester film has an intrinsic viscosity of from 0.43 to 0.57 dl/g.
7. The magnetic recording tape according to claim 1 , wherein the polyester film has a number average molecular weight of from 14,000 to 22,000.
8. The magnetic recording tape according to claim 1 , wherein a surface of the back coat layer has protrusions having a height of 100 mm or more measured with an atomic force microscope in a density of from 20 to 300 in 90 μm square.