MAGNETIC RECORDING MEDIUM

• Main Authors: ISHIKAWA AKIRA, YAMASHITA KAZUTAKA, NAKAYAMA HIDEHIKO
• Format: Patent
• Language: English
• Published: 02.07.1999
• Edition: 6
• Subjects: INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; PHYSICS

PROBLEM TO BE SOLVED: To provide a magnetic recording medium of high density and high capacity which has good electromagnetic conversion characteristics and which hardly causes deterioration in the characteristics even when it is travelled at a high speed for a long time. SOLUTION: This magnetic recording medium has the following features. An acicular ferromagnetic powder having <0.1 μm major axial length is used as a ferromagnetic powder incorporated into a magnetic layer 4. Also a binder having at least one kind of polar group selected from a group of -OSO3 M, -SO3 M, -MO2 , -COOM and -PO4 MM' (wherein M and M' are alkali metals or the like) is used. Pores having 4 to 9.5 nm average pore diameter measured by nitrogen gas adsorption method are formed on the surface of the magnetic layer 4, and the surface roughness Ra of the layer 4 is adjusted to <=8 nm. The coefft. of dynamic friction of the magnetic layer 4 is adjusted to <=0.30 at 20 deg.C and 30% RH and to <=0.50 at 60 deg.C and 70% RH.