KR910008692B1 - Magnetic memory medium and the manufacturing method - Google Patents

Abstract

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Description

Magnetic recording medium and manufacturing method thereof

The present invention relates to a magnetic recording medium, and more particularly, to a magnetic recording medium having excellent durability and a method of manufacturing the same.

Generally, magnetic recording media made by drawing magnetic powder, binder resin, organic solvent and other necessary components on a substrate such as polyester film are contacted with magnetic head and pad during recording and playback. Because of the movement, the magnetic layer is liable to be worn, so that the wear is low and the durability is excellent.

Therefore, one method of improving the abrasion resistance of the magnetic layer is to mix various lubricants in the magnetic filler, for example, hydrocarbon-based lubricants such as squalane and liquid paraffin, silicone-based lubricants such as silicone oil, trichloro A method of mixing a fluorine-based lubricant such as fluoroethylene into a magnetic layer and a method of mixing a saturated fatty acid ester into the magnetic layer have been proposed. However, according to this method, although the wear resistance is surely improved, it is not enough yet. In particular, the above three types of lubricants have a problem in that the pads are contaminated when used in a magnetic layer such as a magnetic disk. Lubricity could not be maintained for a while.

Therefore, the present inventors have made various studies in consideration of such a situation. As a result, when unsaturated fatty acid esters are used together with a hydrocarbon-based lubricant in a magnetic layer, the pads are not contaminated and the abrasion resistance of the magnetic layer is sufficiently improved to provide a magnetic recording medium having excellent durability. It has been found that it can be prepared.

The reason is that the unsaturated fatty acid esters are generally lower in melting point than the saturated fatty acid esters, and remain liquid in a wide temperature range, and are difficult to separate from each other by the synergy of the liquid unsaturated fatty acid esters and the lubricant. It is thought that the reason is that a commercial fluid is formed in the magnetic layer surface.

An object of the present invention is to solve the above-mentioned problems and to provide a magnetic recording medium having excellent durability and a method of manufacturing the same.

Unsaturated fatty acid esters used in the present invention are less volatile and have excellent lubricating performance because they have unsaturated double bonds, and when used in combination with the three types of lubricants, the lubricating functions of both act synergistically. The wear resistance of the magnetic layer is further improved and the effect is maintained for a long time.

Inclusion of these in the magnetic layer of the magnetic disk by the synergistic action of both eliminates the defects and problems when the three types of lubricants are contained alone, and the pad is not contaminated. In addition, when the unsaturated fatty acid ester is used alone, there is a problem that the durability changes with the pressure of the head or when the temperature environment changes, but the durability is also improved by eliminating such variations in durability. Representative examples of such unsaturated fatty acids include oleic acid esters, ellidic acid esters, linoleic acid esters, linolenic acid esters, and the like, and specific examples thereof include oleic acid oleate or oleine-n-butyl.

Examples of hydrocarbon lubricants used together include liquid hydrocarbons such as liquid paraffin, squalane, squalene, synthetic squalane, synthetic squalene, and synthetic squalene at room temperature, such as lepine polymerization oil. For example, tetrafluoroethylene, hexafluoropropylene, trichlorofluoroethylene, perfluoroalkyl polyether, fluorinated alkyl ester, and the like are used as suitable ones. "Crytox" and the like, and various other modified silicone compounds, such as dimethyl silicone oil, methyl phenyl silicone oil, fluoro silicone oil, are used as the lubricant of the silicone type.

These kinds of lubricants have excellent lubrication performance, and when used in combination with the unsaturated and fatty acid esters both act synergistically to further improve the wear resistance of the magnetic layer.

In this case, any of these three types of lubricants may be selected and used, or some of the three types may be mixed and used to achieve the desired effect.

The blending ratio of unsaturated fatty acid esters to such lubricants is preferably 99 to 1 to 1 to 99 by weight ratio (total weight of lubricant to weight of unsaturated fatty acid esters), more preferably 99 to 1 to 50 to 50 Use above.

The lower back pressure ratio of the unsaturated fatty acid ester does not sufficiently improve the wear resistance of the magnetic layer to the pad, while the lower blend ratio of these lubricants does not sufficiently improve the wear resistance of the magnetic layer to the head, especially when the head pressure is large. In addition, the amount of the unsaturated fatty acid ester and the lubricant blended in such a blending ratio is preferably in the range of 0.1 to 40% by weight, and more preferably 0.1 to 20% by weight, based on the magnetic powder. More preferably, it is used in 0.5 to 10% by weight. If too small, the desired performance will not be obtained. If too large, a bleeding out phenomenon may occur on the surface of the magnetic layer to contaminate the magnetic head and reduce the output.

In order to contain the unsaturated fatty acid ester and the lubricant in the magnetic layer, it is dissolved in a suitable solvent such as normal hexane, toluene, methyl alcohol, ethyl alcohol, isopropyl alcohol, freon, and the solution obtained by dissolution is formed in advance. The gravure may be applied to the magnetic layer by means of an applicator, a reverse roll applicator or a knife applicator, or sprayed, or conversely, the magnetic layer may be immersed in the solution.

Or a magnetic substance such as metal iron powder, metal cobalt powder, iron or cobalt alloy powder, γ-Fe ₂ O ₃ powder, Fe ₃ O ₄ powder, the above two intermediate cyclic products or cobalt modified powder thereof or barium ferrite powder. Powders and vinyl chloride resins, vinyl acetate resins, vinyl chloride / vinyl acetate copolymers, vinyl chloride / vinyl acetate / vinyl alcohol copolymers, polyurethane resins, fibrin system resins, polyester resins or sulfonated compounds, vinylidene chloride Acrylonitrile co-polymer, acrylonitrile butadiene copolymer, isoprene rubber, butadiene rubber, etc. are mixed by mixing the binder resin and mixed well, if necessary, by adding a curing agent such as isocyanate compound of low molecular weight to form a magnetic layer You can also do it. The magnetic recording medium is completed by appropriately performing a super calender treatment or polishing treatment on the surface of the magnetic layer thus obtained.

Next, an embodiment of the present invention will be described.

EXAMPLE 1

Γ-Fe ₂ O ₃ Magnetic Powder Containing Cc... 270 parts by weight

VAGH (American Union Carbide company vinyl chloride / vinyl acetate / vinyl alcohol copolymer… 80 parts by weight

N1432J (Acrylic nitrile butadiene co-polymer as a product made in Japan). 15 parts by weight

Coronate L (trifunctional low molecular weight isocyanate compound as a product of Japanese Polyurethane Industry Co., Ltd.). 10 parts by weight

HS-500 (asahi kaobon company carbon black)… 34 parts by weight

Oleic acid oleate 19 parts by weight

Alpha-Fe ₂ O ₃ (α-Fe ₂ O ₃ ) Powder... 11 parts by weight

Methyl isobutyl ketone... 420 parts by weight

toluene… Weight ratio 420

The composition was placed under a ball, mixed and dispersed to prepare a magnetic coating. The magnetic coating was applied to both surfaces of a polyester film having a thickness of 75 µm so as to have a thickness of 3 µm upon drying, and dried to form a magnetic layer. Subsequently, this was immersed in an immersion solution composed of 60 parts by weight squalene and 100 parts by weight normal hexane, and then dried to give a super-calender treatment to squeeze into discs to produce a magnetic disk.

EXAMPLE 2

A magnetic disk was produced in the same manner as in Example 1, except that the same amount of liquid paraffin was used in place of squalane in the composition of the immersion solution of Example 1.

EXAMPLE 3

A magnetic disk was produced in the same manner as in Example 1, except that the same amount of oleic acid-n-butyl was used as an alternative to the oleic acid oleate in the composition of the magnetic paint of Example 1.

EXAMPLE 4

Except for oleic acid oleate in the composition of the magnetic coating of Example 1, the amount of squalane used was 62 parts by weight in the composition of the immersion solution was changed to 20 parts by weight, except that 40 parts by weight of oleate oleate was added additionally In the same manner as in 1, a magnetic disk was produced.

EXAMPLE 5

The magnetic disk was prepared in the same manner as in Example 4 except that 20 parts by weight of "Daffle Oil X 20" (Tricolo Mono Fruor Ethylene, manufactured by Daikin Industries) was used instead of 20 parts by weight of squalane in the composition of the immersion solution of Example 4. Produced.

EXAMPLE 6

A magnetic disk was produced in the same manner as in Example 5 except that the same amount of dimethyl silicone oil was used in place of the "dimple oil # 20" of Example 5.

Comparative Example 1

A magnetic disk was produced in the same manner as in Example 1 except that the oleic acid oleate was used in the composition of the magnetic coating of Example 1.

Comparative Example 2

The magnetic disk was prepared in the same manner as in Example 5 except that oleic acid oleate was proposed in the composition of the immersion solution of Example 5, and the amount of "dip oil # 20" was changed to 60 parts by weight. Produced.

Comparative Example 3

A magnetic disk was produced in the same manner as in Example 6, except that oleic acid oleate was proposed in the composition of the immersion solution of Example 6, and the amount of dimethyl silicone oil was changed to 60 parts by weight.

Comparative Example 4

A magnetic disk was produced in the same manner as in Example 1, except that squalene was excluded from the composition of the immersion solution of Example 1.

Comparative Example 5

A magnetic disk was prepared in the same manner as in Example 5, except that the amount of the oleic acid oleate was 40 parts by weight except for 60 parts by weight except for "dip oil # 20" in the composition of the immersion solution of Example 5. Produced.

Comparative Example 6

N-1 butyl stearate was used in place of oleate oleate in Example 1, and a magnetic disk was produced in the same manner as in Example 1 except that the same amount of liquid paraffin was used instead of squalane.

To prepare the magnetic disks obtained for the durability of the magnetic disks obtained in each of the examples and the comparative examples, 10 magnetic disks were prepared. The magnetic disks were inserted into the anti-pollution jackets and mounted in 10 recording and reproducing apparatuses in order to prevent their contamination. The running time until the regenerative output became 50% of the initial output while the contact pressure of the pad was 25 g / cm 2 and the circumferential speed was 10 m / sec was measured for each recording / reproducing apparatus. Among the ten recording and reproducing apparatuses, the ratio of the shortest running time and the driving time of 50 hours or more was obtained. Also, when the regenerative output became 50% of the initial output, the pads were contaminated.

Table 1 below shows the results.

TABLE 1

As is apparent from the above table, all of the magnetic disks (Examples 1 to 6) made in accordance with the present invention have a shorter running time and a ratio of more than 50 hours of driving, compared to conventional magnetic disks (Comparative Examples 1 to 6). In all cases, there is no spread and no pad is contaminated.

Accordingly, it can be seen that the magnetic recording medium produced by the present invention has excellent durability and improved reliability.

Claims (14)

A magnetic recording medium having a magnetic layer formed by dispersing a magnetic powder on a substrate in a binder, wherein the magnetic layer contains at least one lubricant selected from a hydrocarbon-based lubricant, a fluorine-based lubricant, and a silicone-based lubricant and an unsaturated fatty acid ester. Magnetic recording medium, characterized in that The magnetic recording medium according to claim 1, wherein the unsaturated fatty acid ester is one selected from oleic acid ester, ellidic acid, ester, linoleic acid ester, and linolenic acid ester. The magnetic recording medium of claim 2, wherein the oleic acid ester is one selected from oleic acid oleate and oleic acid-n-butyl. The magnetic recording medium according to claim 1, wherein an amount of the unsaturated fatty acid ester in the magnetic layer and the lubricant is added in an amount of 0.1 to 40% of the Joule ratio relative to the magnetic powder. The magnetic recording medium according to claim 1, wherein the mixing ratio of the unsaturated fatty acid ester to the lubricant is in the range of 99: 1 to 1:99 by weight. The magnetic recording medium of claim 5, wherein the lubricant is a hydrocarbon-based lubricant. The magnetic recording medium of claim 6, wherein the hydrocarbon-based lubricant is selected from liquid paraffin, squalane, suqualene, synthetic squalane, synthetic squalane, and olefin polymerization oil. The magnetic recording medium of claim 1, wherein the lubricant is a fluorine-based lubricant. The self-locking medium according to claim 8, wherein the fluorine-based lubricant is one selected from tetrafluoroethylene, hexafluoropropylene, trichlorofluoroethylene, perluor alkyl polyester, and fluorinated alkyl ester. The magnetic recording medium of claim 1, wherein the lubricant is a silicone-based lubricant. The magnetic relock medium according to claim 10, wherein the silicone-based lubricant is one selected from dimethyl silicone oil, methylphenyl silicone oil, and fluorosilicone oil. When preparing a magnetic paint used in a magnetic recording medium having a magnetic layer formed by dispersing a magnetic powder on a substrate in a binder, an unsaturated fatty acid ester is added to the hydrocarbon-based lubricant, a fluorine-based lubricant, and a silicone-based lubricant in the magnetic layer. And at least one lubricant selected from among the above and the unsaturated fatty acid ester. The method of claim 12, wherein at least one lubricant selected from the hydrocarbon-based lubricant, the fluorine-based lubricant and the silicone-based lubricant is dissolved in an organic solvent to form an immersion solution, and the magnetic recording is performed on the immersion solution. A method for producing a magnetic recording medium in which a medium is immersed so that the unsaturated fatty acid ester and the lubricant are contained in a magnetic layer of the recording medium. The method according to claim 12, wherein at least one lubricant and unsaturated fatty acid ester selected from the hydrocarbon-based lubricant, the fluorine-based lubricant and the silicone-based lubricant are dissolved in an organic solvent and the solution is applied by spray means. A method of manufacturing a magnetic recording medium comprising the lubricant and the unsaturated fatty acid ester contained in a magnetic layer of a recording medium.