High recording density magnetic tape and process for the production thereof

• US 5,445,881 A
• Filed: 06/22/1994
• Issued: 08/29/1995
• Est. Priority Date: 09/10/1993
• Status: Expired due to Fees

• Current Assignee: Minnesota Mining and Manufacturing Co (3M Company)
• Original Assignee: Minnesota Mining and Manufacturing Co (3M Company)
• Inventors: Irie, Shinichi
• Primary Examiner(s): Resan, Stevan A.
• Application Number:
  US08/263,478
• Time in Patent Office: 433 Days
• Field of Search: 428/328, 428/694 BP, 428/694 BF, 428/694 BR, 428/900, 427/130
• US Class Current: 428/328
• CPC Class Codes: G11B 5/70 on a base layer
• CPC Class Codes: G11B 5/71 characterised by the lubricant
• CPC Class Codes: G11B 5/84 Processes or apparatus specially adapted for manufacturing record carriers
• CPC Class Codes: G11B 5/842 Coating a support with a liquid magnetic dispersion
• CPC Class Codes: Y10S 428/90 Magnetic feature
• CPC Class Codes: Y10T 428/256 Heavy metal or aluminum or compound thereof

Abstract

A high recording density magnetic tape with a magnetic layer comprising magnetic particles, binder, curing agent and high molecular weight fatty acid, provided on a non-magnetic substrate, characterized in that the Ra value (center line average height) of the surface of the magnetic layer is 10 nm or less, and that the Z value defined by the following equation is 3.2 or more:

Z=C1/(C2+C3),

wherein

C1 is the spectral integral intensity, measured by X-ray photoelectronic spectral analysis (ESCA), of a carbon atom, which is single-bonded between carbon-carbon atoms,

C2 is the spectral integral intensity, measured by ESCA, of a carbon atom, which is single-bonded to a carbon atom and an atom with an electric negativity degree higher than that of a carbon atom, and

C3 is the spectral integral intensity, measured by ESCA, of a carbon atom, which is double-bonded between carbon-oxygen atoms.

Claims

1. A magnetic recording tape with a magnetic layer comprising magnetic particles, binder, curing agent and high molecular weight fatty acid, provided on a non-magnetic substrate, wherein the Ra value of the surface of the magnetic layer is 10 nm or less, and its Z value represented by the following equation is 3.2 or more:

space="preserve" listing-type="equation">Z=C1/(C2+C3)

wherein

C1 is the spectral integral intensity, measured by X-ray photoelectric spectral analysis, of carbon atoms which are single-bonded between carbon-carbon atoms

C2 is the spectral integral intensity, measured by ESCA, of a carbon atom which is single-bonded with an atom having an electronegativity higher than that of a carbon atom, and

C3 is the spectral integral intensity, measured by ESCA, of a carbon atom which is double-bonded between carbon-oxygen atoms, wherein the surface of the magnetic layer has been abraded by a back and forth contact slide motion against a roll having a surface Ra of 0.04 μ

m or less.

2. The magnetic recording tape of claim 1, wherein the Z value is 3.4 or more.

3. The magnetic recording tape according to claim 1 further comprising a high molecular weight fatty acid in the magnetic layer in an amount ranging from 1 to 3 parts by weight, based on 100 parts by weight of the magnetic particles.

4. The magnetic recording tape according to claim 1 wherein the difference between the coefficient of kinetic friction of the magnetic tape in the forward and reverse directions is 0.01 or less.

5. The magnetic recording tape of claim 1 wherein the magnetic particles are ferromagnetic metal powder.

6. A process for the production of the magnetic recording tape of claim 1 comprising the steps of:

dispersing magnetic pigment, binder resin, curing agent and lubricant in a solvent,

coating the dispersion on a nonmagnetic substrate, drying the dispersion, and curing the dispersion to form a magnetic layer, and

subjecting the surface of the dried and cured magnetic layer to a back and forth contact slide motion by use of a roll having a surface Ra of 0.04 μ

m or less.

7. The process of claim 6 wherein the diameter of the roll is within the range between 2 mm and 1,000 mm.

8. The process of claim 6 wherein the roll is composed of a material selected from stainless steel, tungsten carbide, and titanium carbide.

9. The process of claim 6 wherein the contact slide motion is caused by a tension ranging from 50 to 1000 g/cm.

10. The process of claim 6 wherein the contact slide of the roll to the surface of the magnetic layer is effected at a wrap angle ranging from 10 to 300 degrees.

11. The magnetic tape of claim 1 wherein the diameter of the roll is within the range between 2 mm and 1,000 mm.

12. The magnetic tape of claim 1 wherein the roll is composed of a material selected from stainless steel, tungsten carbide, and titanium carbide.

13. The magnetic tape of claim 1 wherein the contact slide motion is caused by a tension ranging from 50 to 1000 g/cm.

14. The magnetic tape of claim 1 wherein the contact slide of the roll to the surface of the magnetic layer is effected at a wrap angle ranging from 10 to 300 degrees.

15. A process for the production of a magnetic recording tape comprising the steps of:

dispersing magnetic pigment, binder resin, curing agent and lubricant in a solvent,

coating the dispersion on a nonmagnetic substrate, drying the dispersion, and curing the dispersion to form a magnetic layer, and

subjecting the surface of the dried and cured magnetic layer to a back and forth contact slide motion by use of a roll having a surface Ra of 0.04 μ

m or less.