JPS582416B2 - Jikiki Rokutai - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium, and in particular to a magnetic recording card with excellent abrasion resistance that can be used for bank cards, magnetic commuter passes, and similar devices.

In recent years, magnetic recording cards, such as bank cards and magnetic periodicals, have been developed in banking, railways, and other various fields in which a magnetic layer is formed on a card-like substrate such as paper or plastic sheet, and information is recorded on this magnetic layer. Various types of cards are used, such as tickets and magnetic type recording cards.

These magnetic recording cards usually come into violent sliding contact with the magnetic head during playback, so repeated use can cause the magnetic layer to wear off or cause scratches on the surface, reducing playback output and causing malfunctions. It has become.

Therefore, it is required to impart abrasion resistance to the magnetic layer of a magnetic recording card, and conventionally, in order to improve the abrasion resistance, a layer of nitrocellulose resin and a layer of methacrylic resin are added on the magnetic layer. A device in which a two-layer protective film is formed to protect the magnetic layer has been proposed and put into practical use, but the number of times it can be used is approximately 500 times, and although it has met the standard, it is still not fully satisfactory. do not have.

The purpose of the present invention is to obtain a magnetic recording card with excellent abrasion resistance, and the gist of the present invention is to form a copolymer of acrylonitrile and an acrylic ester or a methacrylic ester on a magnetic layer formed on a substrate. A magnetic recording body is characterized in that a protective film is formed by combining.

In the present invention, copolymers of acrylonitrile and acrylic ester or methacrylic ester for forming the protective film include acrylonitrile/methyl acrylate copolymer, acrylonitrile/ethyl acrylate copolymer, and acrylonitrile/methyl methacrylate copolymer. Copolymers, acrylonitrile/ethyl methacrylate copolymers, and the like are preferred, but are not limited thereto.

In addition, as the composition ratio of acrylonitrile increases in the above copolymer, the strength increases and the abrasion resistance improves, but the chemical resistance also increases, making it difficult to dissolve in ordinary solvents and making it difficult to prepare paints. Become.

On the other hand, if the composition ratio of acrylic ester or methacrylic ester is increased, it will be easily dissolved in common solvents such as acetone and ethyl acetate, but strength and chemical resistance will decrease.

Therefore, although it varies depending on the chemical structure of the acrylic ester or methacrylic ester, the content of acrylonitrile is generally 10 to 60% in molar ratio, preferably 40%.
~50% is appropriate.

The magnetic recording medium of the present invention can be manufactured by a commonly used method.

For example, a magnetic coating containing ferromagnetic powder and a binder is applied onto a substrate and dried to form a magnetic layer, and then a solution containing a copolymer of acrylonitrile and an acrylic ester or a methacrylic ester is applied on top of this. It can be obtained by drying to form a protective film and cutting this as appropriate.

Note that the thickness of the protective film is 6 mm from the viewpoint of input/output sensitivity for recording and reproduction.
It is preferably less than μ.

The thus obtained magnetic recording card of the present invention exhibits significantly superior abrasion resistance compared to conventional magnetic recording cards, and can withstand use more than 1000 times.

Next, examples of the present invention will be described.

Example 1 75 parts by weight of γ-Fe203 powder, VAGH (Union)
Manufactured by Carbide, vinyl chloride/vinyl acetate/vinyl alcohol copolymer) 20 parts by weight, dioctyl phthalate 5
A magnetic paint consisting of 55 parts by weight of methyl isobutyl ketone and 55 parts by weight of toluene is applied onto a vinyl chloride sheet substrate having a thickness of about 200 microns to form a magnetic layer having a thickness of about 12 microns after drying.

A solution consisting of 10 parts by weight of acrylonitrile/ethyl acrylate copolymer, 30 parts by weight of methyl isobutyl ketone, 30 parts by weight of ethyl acetate, and 30 parts by weight of acetone was applied onto this magnetic layer, and after drying, the thickness was approximately A protective film of 2 μm is formed.

The vinyl chloride sheet substrate on which the magnetic layer and protective film have been formed is cut into predetermined dimensions to produce a magnetic recording card.

Example 2 75 parts by weight of γ-Fe203 powder, 20 parts by weight of S-LEC BMS (manufactured by Sekisui Chemical Co., Ltd., polyvinyl butyral), Takenate L (manufactured by Takeda Pharmaceutical Co., Ltd., polyurethane prepolymer)
A magnetic paint consisting of 10 parts by weight, 30 parts by weight of methyl ethyl ketone, 40 parts by weight of methyl imbutyl ketone, and 40 parts by weight of toluene was coated on a vinyl chloride sheet substrate with a thickness of about 200 μm, and a magnetic paint with a thickness of about 12 μm after drying was applied. form a layer.

A solution consisting of 10 parts by weight of acrylonitrile/methyl methacrylate copolymer, 30 parts by weight of methyl isobutyl ketone, 30 parts by weight of ethyl acetate, and 30 parts by weight of acetone was applied onto this magnetic layer, and the thickness after drying was approximately 2 μm. Forms a protective film.

The vinyl chloride sheet substrate on which the magnetic layer and protective film have been formed is cut into predetermined dimensions to produce a magnetic recording card.

Comparative Example 1 The magnetic paint of Example 1 was coated on a vinyl chloride sheet substrate with a thickness of about 200μ to form a magnetic layer with a thickness of about 12μ after drying, and then cut into predetermined dimensions to form a magnetic recording card. make.

Comparative Example 2 The magnetic paint of Example 1 was applied onto a vinyl chloride sheet substrate with a thickness of about 200μ to form a magnetic layer with a thickness of about 12μ.
On the magnetic layer, 10 parts by weight of nitrocellulose, 2 parts by weight of Coronate L (polyisocyanate manufactured by Nippon Polyurethane Co., Ltd.), 45 parts by weight of methyl isobutyl ketone, and 4 parts by weight of toluene were added.
A solution consisting of 5 parts by weight was applied to form a protective film with a thickness of approximately 1 μm, and on top of this a solution consisting of lo weight parts of polymethyl methacrylate, 45 parts by weight of methyl ethyl ketone, and 45 parts by weight of toluene was applied to form a protective film approximately 1 μ thick. forms a protective film.

The obtained material is cut into predetermined dimensions to make magnetic recording cards.

Comparative Example 3 The magnetic paint of Example 1 was applied onto a vinyl chloride sheet substrate with a thickness of about 200 μm to form a magnetic layer with a thickness of about 12 μm after drying. A solution consisting of 10 parts by weight of vinyl-vinyl acetate copolymer, 30 parts by weight of methyl isobutyl ketone, 30 parts by weight of ethyl acetate, and 30 parts by weight of acetone is applied to form a protective film having a thickness of about 2 μm after drying.

The obtained material is cut into predetermined dimensions to make magnetic recording cards.

After recording signals on each magnetic recording card obtained in this way, the magnetic head of the playback machine (material: general permalloy)
Pad pressure on the top is about 500y, running speed is about 20cm/SeC
The vehicle was run under the following conditions, and the relative outputs (ratio of the output at each run to the initial output, %) at the 100, 300, 500, and 1000 runs were determined.

The results obtained are shown in the figure. As is clear from the figure, the conventional magnetic recording card according to Comparative Example 1 without a protective film is 1
After 00 runs, the relative output drops to about 50%, and the magnetic layer wears out, making it unusable. In addition, the conventional magnetic recording card according to Comparative Example 2, which has a two-layer protective film, can be used for 500 runs. The surface is scraped and scratches occur during driving, and the relative output decreases to about 70%.

Further, the surface of Comparative Example 3 was scraped and scratched after 500 runs, and the relative output was reduced to about 55%.

On the other hand, the magnetic recording card of the present invention shows almost no scratches or cracks even after running 1000 times, has a relative output of about 90% or more, is sufficiently usable, and exhibits excellent wear resistance.

[Brief explanation of drawings]

The figure is a graph showing the relative output fluctuations of the magnetic recording card of the present invention and the conventional magnetic recording card. 1...Example 1, 2...Example 2, 3
...Comparative Examples 1, 4...Comparative Examples 2, 5.
...Comparative example 3.

Claims (1)

[Claims] 1. A magnetic recording body characterized in that a protective film made of a copolymer of acrylonitrile and an acrylic ester or a methacrylic ester is provided on a magnetic layer formed on a substrate.