JPS583134A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a ferromagnetic metallic thin film type magnetic recording medium excellent in anti-blocking characteristic and rust-preventive effect, by providing a coating film consisting of an antistatic agent, a water-repelling agent, a lubricant and a phenoxy resin on the back side of a non-magnetic substance base. CONSTITUTION:A ferromagnetic metallic thin film is formed on a non-magnetic substance base with vacuum deposition and a coating film consisting of a solid antistatic agent such as carbon black or graphite, a water-repelling agent or a lubricant, such as higher fatty acid, higher fatty acid ester, higher fatty acid metallic salt, higher acid amide, and higher fatty alcohol, and phenoxy resin and, as required, a cross-linking agent, is formed on the back side of the non- magnetic substance base.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a ferromagnetic metal thin film type magnetic recording material, particularly a magnetic tape, in which a coating film mainly composed of a resin material is provided on the opposite surface of the base film to the magnetic layer, thereby preventing the running of the magnetic tape. The purpose is to improve corrosion resistance, antistatic properties, corrosion resistance under high temperature and high humidity environmental conditions, and blocking resistance.

Page 2 A metal thin film obtained by forming a ferromagnetic thin film mainly composed of iron, cobalt, nickel, or an alloy thereof on a polymeric film support such as polyester or polyimide by vacuum evaporation, sputtering, ion blasting, etc. BACKGROUND ART Magnetic tape is ideal for high-density recording, such as recording video signals. However, metal thin films generally have a problem of poor corrosion resistance in high temperature and high humidity environments, especially when exposed to rapid temperature changes in high humidity while being wound up in tape form on a reel, hub, etc. , dew condensation is likely to occur between the opposing magnetic surfaces and the back surface in the rolled state,
In addition, since the gap between the magnetic surface and the back surface is narrow, the water droplets that form once condensed are difficult to evaporate and remain wet on the magnetic surface for a long time, which tends to cause corrosion in that area, and when the corroded area dries, It has become clear that the magnetic surface and the back surface easily adhere (block) through corrosion products.

If the surface properties of the magnetic surface are improved in order to increase the recording density, the gap between the magnetic surface and the back surface in the rolled-up state will become smaller, so the above phenomenon will become more noticeable on the back side of the third base. .

The back side of the metal film type magnetic tape satisfies the general characteristics of magnetic tape such as lubricity, prevention of scratching, and prevention of static electricity. The phenomenon must be addressed.

From this point of view, as a result of examining various materials, a material with excellent blocking resistance and rust prevention effect was discovered.

The basic constituent materials of the present invention include an antistatic agent, a water repellent, a lubricant, and a binding resin.

As the antistatic agent in the present invention, a solid antistatic agent such as carbon black or particulate graphite is used.

Conventionally, organic surfactants such as anionic surfactants, cationic surfactants, and nonionic surfactants that have been used in coated magnetic tapes have good affinity with water, so they prevent the formation of rust. It was unsuitable from the point of view of rust prevention.

Water repellent agents include higher fatty acids such as stearic acid, balmitic acid, myristic acid, lauric acid, and sodium oleate, higher fatty acid esters such as their alcohol esters, polyhydric alcohol esters, and their sodium salts, potassium salts, Lithium salt, calcium salt, barium salt, zinc salt, magnesium salt, aluminum salt, lead salt,
Higher fatty acid metal salts such as chromium salts, cobalt salts, nickel salts, copper bases, iron salts, tin salts, mercury salts, and higher aliphatic alcohols such as lacryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, and lauryl amide; Higher fatty acid amides such as myristic acid amide and palmitic acid amide are used.

Graphite, higher fatty acids, higher fatty acid esters, higher fatty acid metal salts, H1-class fatty alcohols, and higher fatty acid amides have excellent lubricity, but solid lubricants such as molybdenum disulfide and carbon fluoride are also added. This further improves lubricity.

A phenoxy resin is used as the binder resin, which has excellent compatibility with antistatic agents, lubricants, and water repellents, and excellent dispersibility of solid particles.

1. Improved properties of butylated melamine resin, butylated urea resin, chemical resistance, and abrasion resistance.

Phenoxy resin, stearic acid and graph 1a)
'lr was added, a solvent was added, and a dispersion treatment was performed using a ball mill to prepare a coating solution. The coating material was applied to the back side of a metal thin film type magnetic tape on which a cobalt alloy was vapor-deposited on a polyethylene terephthalate film. No rust or blocking was observed with this tape even under high temperature and high humidity conditions. When I ran it using a video tape recorder, it ran stably and there was hardly any noise due to charging.

The present invention will be specifically explained in detail below.

Example 1 The following composition was charged into a ball mill, stirred for 40 hours, and subjected to a dispersion treatment.

The obtained paint was coated with cobalt (80%) and nickel (2
0%) on the back side of a ferromagnetic alloy thin film. After drying, it was cut to an appropriate width to create a magnetic tape. Coating film thickness is 3
．． It was 0μ. This person will be the sample person.

Example 2 The following composition was charged into a ball mill, stirred for 4 hours,
A paint was produced by carrying out dispersion treatment.

7. The obtained paint was applied by a percoater method to the back side of a ferromagnetic alloy thin film of cobalt (80%) and nickel (20%) prepared by vacuum deposition on a polyester film. After drying, it was cut to an appropriate width to produce a magnetic tape. The coating film thickness was 3.8μ. This tape is designated as sample B.

Example 3 The following composition was charged into a ball mill, stirred for 40 hours,
A paint was prepared by performing a dispersion treatment.

The obtained paint was applied using a bar coater method to the back side of a ferromagnetic alloy thin film of cobalt (80%) and nickel (20%) prepared by vacuum deposition on a polyester film. After drying, it was cut to an appropriate width to produce a magnetic tape. The coating film thickness was 4.3μ. This tape is designated as sample C.

Example 4 The following composition was charged into a ball mill, stirred for 40 hours,
A paint was prepared by performing a dispersion treatment.

The paint obtained on page 9 was applied by a percoater method to the back side of a ferromagnetic alloy thin film of cobalt (80%) and nickel (20%) prepared by vacuum deposition on a polyester film. After drying, it was cut to an appropriate width to produce a magnetic tape. The coating film thickness id was 3.5μ. Use this tape as a sample.

Example 5 The following composition was charged into a ball mill, stirred for 40 hours,
A paint was prepared by performing a dispersion treatment.

The resulting paint was applied using a bar coater method to the back surface of a thin ferromagnetic alloy film of cobalt (8%) and nickel (20%) prepared by vacuum deposition on a polyester film. After drying, it was cut to an appropriate width to produce a magnetic tape. The coating film thickness was 3.3μ. This tape is designated as sample E.

Samples A, B, and C were prepared in Examples 1 to 5 above.

An environmental test was conducted by leaving D, E and uncoated samples wound on a reel at a temperature of 60° C. and a temperature of 90%. The contact angle of the coating film with water was also measured to examine its water repellency. The results are shown in the table below.

Table ■ As is clear from Table 1, the monokoke repellent according to the present invention 11
7. - Hydrogenation prevents moisture from entering and improves the corrosion resistance of the magnetic thin film.

Furthermore, a running test was conducted using a test machine having the same functions as a commercially available VTR. In the samples whose back side was not coated, running was unstable, and noise thought to be caused by triboelectric charging was occasionally observed, but samples A, B, C, and D.

In E, running was stable, and no noise was observed that could be caused by frictional charging.

Furthermore, 1o on a stainless steel block with a mirror finish.
! ? Frictional resistance was measured under load. The frictional resistance of the uncoated sample on the back side was 1. Table 3 shows the frictional resistance of each sample when oo.

As is clear from Table (3), the material according to the present invention has low frictional resistance and excellent lubricity.

As described above, according to the present invention, corrosion resistance and blocking resistance can be easily improved.

Claims (1)

[Claims] In a magnetic recording medium, a ferromagnetic metal thin film is formed on a non-magnetic substrate, and at least one of graphite and carbon black, a higher fatty acid, a higher fatty acid ester, and a higher fatty acid metal are coated on the surface of the substrate opposite to the ferromagnetic metal thin film. 1. A magnetic recording medium characterized by forming a coating film consisting entirely of phenoxy resin and at least one selected from the group consisting of salt, higher fatty acid amide, and higher aliphatic alcohol.