JPH01100731A - Magnetic recording medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

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, these magnetic recording media are moving toward high-density recording, and in order to reduce spacing loss during short wavelength recording and increase output and signal-to-noise ratio, the surface of the magnetic layer has become increasingly smooth. In particular, in the case of a medium that passes through a complicated running system, such as a video tape or a computer chip 1, by making the surface of the magnetic layer highly smooth, the coefficient of friction between the magnetic surface and various running posts, rotating cylinders, etc. increases. For this reason, the running properties are very poor υ, and defects such as tape damage and running stop are likely to occur when used under harsh environments such as low temperature, low humidity, and high temperature and high humidity.

Conventionally, in order to solve these problems, solid lubricants such as carbon black have been used (for example, Japanese Patent Application No. 6L-27124).
and the use of various organic lubricants (for example, Japanese Patent Application No. 1-29)
3906) has been proposed.

Problems to be Solved by the Invention In addition to the above-mentioned demand for highly smooth magnetic recording media, the use of these magnetic recording media in harsh environments is increasing, and high electromagnetic It was difficult to achieve both conversion characteristics and stable running performance.

An object of the present invention is to solve the above problems and provide a magnetic recording medium having high electromagnetic conversion characteristics and stable running performance.

Means for Solving the Problems In order to solve the above problems, the present invention provides a magnetic recording medium in which a magnetic recording layer made of ferromagnetic powder and a binder is provided on a non-magnetic supporting material. The recording layer is coated with spherical fine silica powder having a particle size of 0.1 μm to 1.6 μm.
It is characterized by containing 1 to 5 parts by weight.

Function: As a result of extensive research, the inventors of the present invention have found that by including fine spherical silica powder in the magnetic layer, the runnability can be significantly improved without impairing the stain magnetic conversion characteristics.

The spherical fine silica powder 5IQ2 used in the present invention is a white fine powder having a perfect spherical shape and a particle size of 0.1 μm to 1.5 μm. Furthermore, A4. It may contain impurities such as Ca and Na.

Silica has a relatively high hardness of 6, has low adhesion, and is spherical, so the top part of the added silica is exposed on the magnetic surface. It is thought that this reduces the actual contact area between the two wheels and significantly improves running performance.

In addition, the effect of improving runnability is remarkable, and since the specific surface area is small compared to the particle size, dispersion is easy and a highly smooth magnetic surface can be obtained, so that excellent electromagnetic conversion characteristics such as high output and high C/N ratio can be obtained.

If the particle size of the spherical fine silica powder is 0.1 μm or less, the thixotropy of the magnetic paint increases, making it impossible to obtain the desired high smoothness of the magnetic surface, and also making it impossible to obtain the effect of reducing the coefficient of friction. Furthermore, if the particle size is 1.6 μm or more, the surface properties of the magnetic surface will deteriorate and the electromagnetic conversion characteristics will deteriorate.

The amount of spherical fine silica powder to be added is 0.1 to 6 parts by weight, since there is no effect if it is less than 1 part by weight, and if it is more than 5 parts by weight, the output will decrease due to a decrease in the magnetic layer density. Appropriate.

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 agent added as necessary, inorganic pigment such as abrasive, the above-mentioned spherical fine silica powder, binder 1 dispersant, hardener, lubricant, etc. are mixed together with an organic solvent in a mixer. A magnetic coating solution having a desired component ratio is prepared by sufficiently mixing and dispersing the components.

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.

Sharp S material! : alpha alumina, r alumina, titanium oxide, red iron oxide, chromium oxide, silicon carbide.

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

! Mixed drug! : Fibrous resins such as nitrocellulose and cellulose acetyl butyrate, vinyl chloride vinyl acetate copolymer resins, vinylidene chloride resins, polyurethane resins, polyamide resins, urea resins, epoxy resins,
Polyester resin, epoxy resin, fluorocarbon resin, 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. (For example, Unexamined Japanese Patent Publication No. 6 o-17
7427J)) Examples of dispersants include higher fatty acids, higher fatty acid metal salts, higher fatty acid amides, higher alcohols, phosphoric acid esters, glycerin, and silane coupling agents.

There are titanium coupling agents, aluminum coupling agents, etc., which are added as necessary.

Examples of the curing agent include polyfunctional low-molecular isocyanates, low-molecular polyamines, and low-molecular polyamides 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 isobutyp ketone, toluene, benzene, xylene, cyclohexanone, ethyl acetate, butyl acetate, tetrahydrofuran, thimethylformamide, ethyl alcohol, isopropyl alcohol, ethylene chloride, ethyl cellosolve, etc. liquid is used.

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

Pin Mill, Pebble Mill, Nutone Mill, Day Silver,
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 may be performed, or the non-magnetic support may be subjected to a corona discharge or plasma discharge treatment.

As the coating method, a doctor blade method, a clavier roll method, a reverse roll method, a quinu roll method, a spin cord method, and a Nuplay coat method are used. In order to improve the smoothness of the coating film immediately after application, a smoother may be used in contact with it. This includes parsing smoother, wire smoother,
A film smoother is used.

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 properly align the magnetic powder in the coated film.

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 smoothen the surface of the wide magnetic layer that has been coated and dried, surface treatment is performed using a nu-/<-calender consisting of an elastic roll and a mirror roll. Preferred materials for the elastic roll include nitrile rubber, natural rubber, nylon, polyamide, and polyimide. Calendar conditions include temperature 60-1
00℃, pressure 60~4oot/cII&, speed 50~4
oOm/min is desirable.

One part of the raw fabric roll obtained in this way is shredded into 2-inch width pieces to produce a deo tape.

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

Go-containing - Fe203 magnetic iron oxide 10-0 parts Ha 8000e Specific surface area 44 m'/q Polyurethane resin 10 parts Nitrocellulose 10 parts Alumina abrasive 5 parts Spherical silica fine powder 1 part Particle size 0
．． 5μm MEK 150 parts toluene
150 parts of the above composition was partially dispersed in a sand mill for 10 hours, filtered through a filter having a filtration accuracy of 0.3 μm, coated on a 14 μm thick polyethylene terephthalate to a thickness of 4 μm, oriented and dried to obtain a jumbo roll.

One portion of this was cut into 2-inch width pieces to prepare a videotape.

(Example 2) In the above composition, spherical silica fine powder (particle size 0.6
μm) instead of spherical silica fine powder (particle size 1.0 μm)
A videotape was produced in the same manner as in Example 1, except that 0.5 part of m) was used.

(Comparative Example 1) A videotape was produced in the same manner as in Example 1 except that the spherical silica fine powder was not added to the above composition.

(Comparative Example 2) In the above composition, spherical silica fine powder (particle size 0.5
carbon black (particle size 50 nm) instead of carbon black (particle size 50 nm)
).) A videotape was produced in the same manner as in Example 1 except for using 3 copies of the following.

Friction coefficient and RF output for each of the above samples In the above case, (1) the friction coefficient was determined by making the tape surface contact along half the circumference of an aluminum alloy drum with a diameter of 60 nm, and increasing the input tension to the drum by 409 degrees. Tape running speed is 3,
The exit tension Xg when set to 3cW1 was measured, and the friction coefficient was determined from the following equation.

π λ side tension crab 40g (2) RF output is 5-VH8 system VTRNV-FSl (
Matsushita Electric Industrial Co., Ltd. was used to perform recording and playback at the optimum recording current value at a frequency of 7 MHz, and the RF output after head amplifier amplification was measured using a spectrum analyzer, and comparative example 2 was expressed as OdB as a relative value. I showed it.

As is clear from the above coating, the magnetic chi 7° obtained in the above manner has a reduced coefficient of friction compared to conventional products and has an RF
It is also excellent with improved output.

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.

Effect of the invention As detailed above, one aspect of the present invention improves running performance.

An excellent magnetic recording medium that has both good electromagnetic conversion characteristics can be obtained, and has great practical value.

Claims (1)

[Claims] A magnetic recording medium comprising a magnetic recording layer made of ferromagnetic powder and a binder on a non-magnetic support, the magnetic recording layer containing spherical fine silica powder with a particle size of 0.1 μm to 1.5 μm. A magnetic recording medium comprising 0.1 to 6 parts by weight.