JPS6124018A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To decrease the coefft. of friction and to improve largely durability by coating a magnetic layer which consists essentially of tristearyl phosphate and into which a higher fatty acid and aliphat. dibasic acid diester lubricating agent are incorprated on a base. CONSTITUTION:This magnetic recording medium is formed by coating the magnetic layer which consists essentially of tristearyl phosphate and in which the higher fatty acid and aliphat. dibasic acid diester are incorporated on the base. The tristearyl phosphate when incorporated into the magentic layer decreases the coefft. of friction of said layer and improves the wear resistance of the magnetic layer. The higher fatty acid is adsorbed to the magnetic powder when dispersed in a magnetic paint. The higher fatty acid adsorbed thereto ats as a dispersant or lubricating agent of the magnetic powder and improves the adhesiveness between the base and the magnetic layer. The aliphat. dibasic acid diester has good affinity to the higher fatty acid, tristearyl phosphate and binder and therefore the relieaf of the tristearyl phosphate on the surface of the magnetic layer is suppressed and the wear resistance of the magnetic layer is improved as the sustaining effect of the lubricating agent act synergistically.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a magnetic layer by applying magnetic powder, carbon black, abrasive powder together with a binder, lubricant, etc. onto a support such as a polyester film. The present invention relates to a magnetic recording medium provided with.

Conventional configurations and their problems In general, magnetic recording media come into intense sliding contact with magnetic heads and pads during recording and reproduction, so the magnetic layer is easily abraded, and there is a need for a highly durable medium with little abrasion. Therefore, as a conventional method for improving the wear resistance of the magnetic layer, various lubricants such as stearic acid, oleic acid, butyl stearate, dioleyl adipate, and stearamide have been added to the magnetic layer. , silicone oil, liquid paraffin.

Although it has been proposed that a per7o-roalkyl polyether or the like is incorporated into the middle layer, the improvement in the wear resistance of the magnetic layer is still insufficient.

In addition, for example, there has already been a proposal to use higher fatty acids and dioleyl adipate together and incorporate them into the magnetic layer to improve wear resistance compared to the conventional method. 〇Object of the Invention The object of the present invention is to eliminate lubricant from protrusion on the surface of the magnetic layer, prevent contamination of the magnetic head and pad, and further improve durability by lowering the coefficient of friction. The present invention provides a magnetic coating film with greatly improved properties.

Structure of the Invention The structure of the present invention is such that a magnetic layer containing tristearyl phosphate as a main component, a higher fatty acid, and an aliphatic dibasic acid diester lubricant is coated on a support.

The higher fatty acid used in the present invention has 12 carbon atoms.
18 saturated fatty acids, and unsaturated fatty acids having 18 carbon atoms, specific examples of which include lauric acid, myristic acid, valmitic acid, stearic acid, and oleic acid.

These higher fatty acids are adsorbed by the magnetic powder when dispersing the magnetic paint, and have the effect of acting as a dispersant or lubricant for the magnetic powder and improving the adhesion between the polyester film support and the magnetic layer. .

Furthermore, as the main component of the present invention, higher alcohol phosphate tristearyl phosphate, which is used in combination with higher fatty acids and aliphatic dibasic acid diesters, has a melting point of 43°C.
It is a white solid substance, and when contained in the magnetic layer, the coefficient of friction decreases and the wear resistance of the magnetic layer is significantly improved.

On the other hand, trioleyl phosphate (liquid), which is a higher alcohol phosphate ester (melting point: 30'C or less), which has traditionally been used as an extreme pressure lubricant, is liquid at room temperature. Therefore, when contained in the magnetic layer, the friction coefficient becomes high and the wear resistance of the magnetic layer is significantly reduced.

In addition, in the present invention, the aliphatic dibasic acid diesters used in combination with high-resolution fatty acids and tristearyl phosphate include branched alcohols with 18 carbon atoms, which have excellent compatibility and lubricating effects, unsaturated alcohols with 18 carbon atoms, and adipine. Di-branched alkyl or dialkenyl aliphatic dibasic acid diesters are used. Examples of such aliphatic dibasic acid diesters include diisooctyl adipate, diindef-ruadipate, diisotridecyl adipate, diincetyl adipate, diisostearyl adipate, and dioleyl adipate.

In particular, this type of aliphatic dibasic acid ester has a relatively low viscosity, and even if it is contained in the magnetic layer, unlike the above-mentioned higher fatty acids, it does not significantly deteriorate the mechanical strength of the binder. In addition, since the aliphatic dibasic acid ester has good compatibility with the higher fatty acid, tristearyl phosphate, and binder used together, the protrusion of tristearyl phosphate, which is a crystalline solid, onto the surface of the magnetic layer is suppressed.
Moreover, the sustained effects of these lubricants act synergistically to further improve the wear resistance of the magnetic layer.

The mixing ratio of higher fatty acid, tristearyl phosphate, and aliphatic dibasic acid diester lubricant is 10:80:10-30 by weight (higher fatty acid: tristearyl phosphate: aliphatic dibasic acid diester lubricant). vs. 40
It is preferable to set it within a range of 3o.

If the proportion of any of these lubricants used in combination is less than this range, the abrasion resistance of the magnetic layer will not be sufficiently improved. In particular, if the blending ratio of tristearyl phosphate is too low, no improvement in durability can be expected, and if the blending ratio of aliphatic dibasic acid diester is too low, the lubricant tends to come out.

Furthermore, if the blending ratio of higher fatty acids is too high, the mechanical strength of the magnetic layer will deteriorate and the durability will not improve, and if the blending ratio of aliphatic dibasic acid diester is too high, the abrasion resistance of the pad will deteriorate. descend.

Furthermore, tristearyl phosphate is in the form of a crystalline solid and does not mix well with binders or magnetic powder, so if the proportion of tristearyl phosphate is too high,
The surface of the magnetic layer will bulge out and contaminate the head and pads.
There is a risk of reducing output.

The amount of higher fatty acid, tristearyl phosphate, and aliphatic dibasic acid diester blended in such a blending ratio is the sum of these three lubricants, and
A range of 1 to 16% by weight is desirable. In addition, if it is outside this range and is too small, the initial effect will not be obtained,
If there is too much, it may stand out on the surface of the magnetic layer, contaminating the magnetic head or pad, and reducing the output.

In addition, in order to contain higher fatty acids, tristearyl phosphate, and aliphatic dibasic acid diesters in the magnetic layer,
A solution obtained by dissolving these in a suitable solvent such as trichlorotrifluoroethane is applied or sprayed onto a pre-formed magnetic layer.

Alternatively, the magnetic layer may be immersed in the above solution.
Alternatively, these may be incorporated by kneading them together with magnetic powder and a binder to form a magnetic layer.

DESCRIPTION OF EXAMPLES The present invention will be described below with reference to Examples. In the example,
Parts are by weight unless otherwise specified.

Example 1 100 parts of Co-containing magnetic iron oxide powder, part a of nitrified cotton (manufactured by Asahi Kasei Industries, Ltd., trade name 5L-1), 20 parts of polyurethane resin (manufactured by Nippon Polyurethane Industries, Ltd., trade name N-2304),
2 parts lecithin, 2 parts stearic acid, 16 parts carbon black
1 part, 4 parts of alumina powder, 80 parts of toluene, 80 parts of methyl ethyl ketone, and 80 parts of cyclohexanone were mixed in a ball mill for 12 hours, and for 100 parts of this mixture,
Furthermore, 10 parts of a polyisocyanate compound (manufactured by Nippon Polyurethane Kogyo Co., Ltd., trade name: Coronet L) was added, and after mixing well, the magnetic paint was coated on a polyester film with a thickness of 75 μm, so that the thickness of the magnetic paint film after drying was The diameter is 1.3μm
A magnetic layer was formed by coating on both sides so as to have the following properties.

Next, this was mixed with 0.1 part of stearic acid and 0.8 parts of tristearyl phosphate [MTL13610, manufactured by Monomoto Yushi Co., Ltd.
Dioleyl adipate [MTL118 manufactured by Monomoto Yushi Co., Ltd.]
The magnetic disk was immersed for a short time in a solution consisting of 0.1 part of trichlorotrifluoroethane and 100 parts of trichlorotrifluoroethane, dried, punched out into a disk shape, and the surface of the magnetic layer was polished to produce a magnetic disk.

Example 2 In Example 1, 2 parts of stearic acid Q, 0.6 parts of tristearyl phosphate, and 0.6 parts of dioleyl adipate were added.
A solution consisting of 2 parts of trichlorotrifluoroethane and 100 parts of trichlorotrifluoroethane was prepared, and a magnetic disk was prepared in the same manner as in Example 1.

Example 3 In Example 1, 0.3 part of stearic acid, 0.4 part of tristearyl phosphate, and 0.4 part of dioletheryl adipate were added.
A solution consisting of 3 parts of trichlorotrifluoroethane and 100 parts of trichlorotrifluoroethane was prepared, and a magnetic disk was produced in the same manner as in Example 1.

Comparative Example 1 In the composition of the impregnating solution in Example 1, dioleyl adipate was omitted, and stearic acid was added from 0.1 part to 0.5 part.
Comparative Example 2 A magnetic disk was produced in the same manner as in Example 1 except that tristearyl phosphate was changed from 0.8 parts to 0.6 parts.Comparative Example 2 In the composition of the impregnating solution in Example 1, Stearyl phosphate was omitted, stearic acid was changed from 0.1 part to 0.6 part, and total dioleyl adipate was changed from 0.1 part to 0.6 part. Comparative Example 3 A magnetic disk was prepared in the same manner as in Example 1 except for the following: In the composition of the impregnating solution in Example 1, stearic acid was omitted, tristearyl phosphate was changed from 0.8 parts to 0.6 parts, and A magnetic disk was prepared in the same manner as in Example 1, except that the amount of dioleyl adipate was changed from 0.1 part to 0.6 part.

Comparative Example 4 In the composition of the impregnating solution in Example 1, trilauryl phosphate [MTL-137' manufactured by Monomoto Yushi Co., Ltd.] was used instead of tristearyl phosphate.

Comparative Example 6 In the composition of the impregnating solution in Example 1, trioleyl phosphate [MTL- manufactured by Monomoto Yushi Co., Ltd.] was used instead of tristearyl phosphate. Except for using 1381,
A magnetic disk was produced in the same manner as in Example 1.

In order to examine the acceleration durability of the magnetic disks obtained in Examples and Comparative Examples, each magnetic disk was inserted into a jacket and loaded into a recording/reproducing device, and then subjected to a normal environment (26
℃, 60% RH), pad pressure 47. I5gr,
Continuous rotation was performed at a rotation speed of 300 T, p, m, and the rotation speed until the reproduction output of the magnetic disk became 70% or less of the initial output was measured.

The dynamic friction coefficient of the magnetic layer was measured with a cursor-type dynamic friction coefficient measuring device (manufactured by Kyowa Kagakusha).

In addition, the determination of whether the lubricant has embossed onto the surface of the magnetic layer 2 is carried out by storing the magnetic disk under normal conditions (26°Ce).

%RH) for 30 days and visually inspected.

Table 1 shows the results.

(Hereinafter, blank) Effects of the Invention As is clear from Table 1, the magnetic disk obtained by the present invention has no lubricant protruding on the surface of the magnetic layer, and has a low coefficient of friction, so that the magnetic layer has a low coefficient of friction. Good abrasion resistance and excellent durability.

Claims (1)

[Claims] A magnetic recording medium characterized in that a magnetic layer containing tristearyl phosphate as a main component and containing a higher fatty acid and an aliphatic dibasic acid diester lubricant is applied onto a support.