JPS63175224A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the durability of the title medium by forming a magnetic layer contg. fluorine-modified silyl-polymethylene on a supporting body. CONSTITUTION:A magnetic layer consisting of magnetic powder and a binder is provided on a nonmagnetic supporting body to form the magnetic recording medium. In the medium, fluorine-modified silyl-polymethylene is incorporated into the magnetic layer. namely, the fluorine-modified silyl-polymethylene is low in stickiness and appropriately compatible with the resin to be used as the binder as compared with the conventional lubricant, hence the sticking between tape and head is disturbed at a relatively low temp., and the friction coefficient is reduced. As a result, the durability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to magnetic recording media such as magnetic tapes and magnetic sheets used in audio equipment, video equipment, computers, and the like.

BACKGROUND OF THE INVENTION In recent years, the relative speed of tape heads has tended to increase as the recording frequency of each of these magnetic recording media has been increased to obtain higher recording densities. Tape 1. As the relative speed increases, head wear increases, resulting in decreased head life, unstable output due to head seizure, and increased dropout due to increased head powder after long-term use. Many problems related to lubrication are occurring. A number of lubricants have been considered to solve these tape-head interface problems.

Problems to be Solved by the Invention When adding these lubricants in too large an amount, it will cause an increase in head powder adhesion and a decrease in coating film strength, and if too little added, an increase in head wear and a head seizure phenomenon will occur. . Therefore, there is a problem in that it is necessary to solve the paradoxical phenomenon of lubricating the RAD interface to the tape over a long period of time with as little lubricant as possible.

Means for Solving the Problems In order to solve the above problems, the present invention provides a magnetic recording medium in which a magnetic layer made of magnetic powder and a binder is provided on a non-magnetic support, in which the magnetic layer is fluorine-modified. It contains silpolymethylene.

Function: As a result of extensive research, the inventors of the present invention have found that the durability of a magnetic recording medium can be dramatically improved by adding fluorine-modified silpolymethylene to the magnetic recording layer as described above.

The basic groove phase unit of the fluorine-modified silpolymethylene used in the present invention is, n and m are each integers of 1 to 1Q, and R is CF
3. C2F s + ((CH2) sCt F
2 t +1] (8=1 to 2o, t=1 to 10).

Conventionally, silicone oil,
Fluorine oil, higher fatty acids such as myristic acid, palmitic acid, stearic acid, oleic acid, and behenic acid, esters of these higher fatty acids and monohydric or polyhydric alcohols, or esters of lower fatty acids and higher alcohols are used. was.

Compared to these lubricants, fluorine-modified silopymethylene has low adhesiveness and moderate compatibility with the resin used as a binder, reducing the coefficient of friction by preventing adhesion between tape heads at relatively low temperatures. .

As a structural unit of fluorine-modified silpolymethylene, x +
When 7 is less than 1Q, sufficient lubricity is not exhibited. Phenyl group, vinyl group, halogenated alkyl group, alcohol group instead of methyl group in the side chain.

Introducing carboxylic acid groups, amino groups, nitrile groups, etc. is effective in changing adsorption to magnetic powder and compatibility with dispersible binders.

EXAMPLE Next, a method for manufacturing a magnetic recording medium according to the present invention will be explained using a magnetic tape as an example.

First, the magnetic layer is formed as follows.

Magnetic powder, antistatic agents added as necessary, inorganic pigments such as abrasives, binders, dispersants, curing agents, the above-mentioned lubricants, etc. are mixed together with an organic solvent in a mixer and dispersed in a single axiom to form the desired mixture. A magnetic coating liquid having a component ratio is prepared.

The magnetic powder used here is magnetic iron oxide.

Any of cobalt-magnetized iron oxide, chromium dioxide, metallic magnetic powder, barium ferrite magnetic powder, iron nitride magnetic powder, iron carbide magnetic powder, etc. may be used.

As the antistatic agent, a required amount of inorganic conductive fine powder such as carbon black or graphite powder or an organic surfactant is used.

As abrasives, alpha alumina, r alumina, titanium oxide, red iron oxide, chromium oxide, and silicon carbide are used.

One or a combination of two or more of inorganic high-hardness fine particles such as cerium oxide boron carbide and silicon oxide, and plastic fine powder are used.

Binding agents, nitrocellulose, cellulose acetyl butyrate and other fiber-based resins, vinyl chloride vinyl acetate copolymer resins, vinylidene chloride resins, polyurethane resins, polyamide resins, urea resins, epoxy resins, polyester resins, epoxy resins, Fluororesin, acrylonitrile resin.

One or a combination of two or more of phenol resins and derivatives of these resins are used in consideration of dispersibility and durability of the coating film.

Dispersants include higher fatty acids, higher fatty acid metal salts, higher fatty acid amides, higher alcohols, phosphoric acid esters, glycerin, and silane coupling agents.

Titanium coupling agents, aluminum coupling agents, etc. are added as necessary.

Examples of the curing agent include polyfunctional low-molecular incyanate, low-molecular polyamine, and low-molecular polyamide when thermosetting is used, and polyfunctional low-molecular polyepoxy when electron beam curing or radiation curing is used.

To further improve reactivity, organic tin compounds, acidic catalysts,
A crosslinking promoter or crosslinking inhibitor such as an alkaline catalyst may be added.

Examples of organic solvents include mixtures of methyl ethyl ketone, methyl isobutyl ketone, toluene, benzene, xylene, cyclohexanone, ethyl acetate, butyl acetate, tetrahydrofuran, thimethylformamide, ethyl alcohol, inpropyl alcohol, ethylene chloride, ethyl cerene rub, etc. used.

These compositions are sufficiently mixed together with a solvent in a mixer to produce a magnetic paint having a desired component ratio. Mixing machines include paint shakers, ball mills, bot mills, dyna mills, and sand mills.

pin mill, pebble mill, stone mill, dissolver,
Attritor, high speed mixer, Henschel mixer, planetarium mixer, pressure kneader.

A continuous kneader, three-roll mill, two-roll mill, ultrasonic disperser, etc. may be used.

The magnetic paint thus obtained is applied onto a non-magnetic support. In order to improve the adhesion between the magnetic coating film and the non-magnetic support, an anchor coating treatment is performed, and the non-magnetic support is sometimes subjected to a corona discharge treatment or a plasma discharge treatment.

As the non-magnetic support used here, plastic films such as polyethylene terephthalate, cellulose acetate, polyamide, polyimide, nylon, etc., paper, glass, ceramic, silicon wafer, aluminum, etc. are used depending on the form of the media.゛As for the coating method, a doctor blade method, a clavier roll method, a reverse roll method, a kiss roll method, and a spin cord method are used. In order to improve the smoothness of the coating film immediately after application, a smoother may be brought into contact with it. A bar smoother, wire smoother, or film smoother is used for this purpose.

Immediately before drying, an orientation treatment is performed using an orientation device using a permanent magnet or an electromagnet, or a randomizer, in order to bring the magnetic powder in the coated film into an appropriate orientation state.

After this, the coating film is dried to remove the solvent. Heat curing treatment, electron beam curing treatment, annealing treatment, etc. are also performed as necessary.

In order to further smooth the coated and dried wide magnetic layer surface, a super calender consisting of an elastic roll and a mirror roll is used to perform surface treatment. Preferred materials for the elastic roll include nitrile rubber, natural rubber, nylon, polyamide, and polyimide. Calendar conditions include temperature 60-10
0℃, pressure a O-400Ky/cIII, speed 50~
400m/min is desirable.

Furthermore, a top coat treatment to improve the durability of the coating film and a back coat treatment to improve running properties may be performed.

(Example 1) The magnetic paint was prepared as follows.

CO adhesion r Fe2O3 magnetic iron oxide powder 100 parts B
ET specific surface area 4s, 17y Coercive force 6800e Vinyl chloride-vinyl acetate copolymer resin 10 parts Polyurethane resin 10 parts Chromium oxide
7 parts carbon black
3 parts Fluorine-modified silopymethylene 0.1 part (molecular weight 5000.R: CF3) Methyl ethyl ketone 100 parts Toluene 100 parts Cyclohexanone 30 parts The above composition was mixed and dispersed in a continuous kneader for 1 hour, and then a curing agent (low molecular incyanate : 6 parts of Coronate L) were added and further mixed and dispersed in a sand mill for 5 passes, and filtered through a filter having an average pore size of 0.8 μm. This magnetic paint has a thickness of 14 μm.
After coating to a thickness of 4 μm on a thick base film, orienting and drying, the magnetic layer was surface-treated using a super calender roll to prepare a jumbo roll.

The cono jumbo roll was heat-cured at 60° C. for 10 hours and then cut into 1/2 inch widths to prepare video tapes.

(Example 2) Molecular weight of Example 1: 5000, R: CF3(7)
Molecular weight 2000 instead of fluorine-modified silpolymethylene
, R: C2F6 fluorine-modified silpolymethylene.
After using three copies, a videotape was produced in the same manner as in Example 1.

(Comparative Example 1) A videotape was produced in the same manner as in Example 1 except that fluorine-modified silopymethylene was not added.

Steel life and head wear amount were measured for each of the above samples.

In the table above, (1) Steel Life has modified a VH3 system VTR.
The time required for the output to decrease by s dB compared to the initial state when the sample was in a steel state at ℃ was measured.

(2) Hair )'Abrasion 1iVH3 method VT RA
Using G6200 at 5℃ 80% R, H, 200℃ under atmosphere
The difference in head protrusion before and after running a pass (4oO hours) was measured.

As is clear from the above table, the magnetic tapes obtained as described above are excellent in that they have improved steel life and reduced head wear compared to conventional products.

In the embodiments, only magnetic tape has been described, but it goes without saying that the present invention can be applied not only to magnetic tape but also to magnetic recording media such as magnetic sheets and magnetic cards.

Effects of the Invention As detailed above, according to the present invention, a magnetic recording medium with excellent lubricity can be obtained, and its practical value is great.

Claims (1)

[Claims] A magnetic recording medium characterized in that a magnetic layer containing fluorine-modified silopymethylene is formed on a support.