JPS6278717A - Magnetic disk - Google Patents

Abstract

PURPOSE:To improve a lubricating effect and durability by incorporating an aliphat. compd. having an epoxy group or butoxy group into a magnetic disk on the magnetic recording surface side in contact with a magnetic head and incorporating a fatty acid ester to the side in contact with a pad opposite from the magnetic recording surface side. CONSTITUTION:The aliphat. compd. having the epoxy group or butoxy group to be incorporated into the magnetic disk on the magnetic recording surface side in contact with the magnetic head has good affinity to a metal and fits well to the magnetic head made of metal. The aliphat. compd. having the epoxy group or butoxy group of 13-50 C is preferable and butoxyethyl stearate, butyl stearate, etc., are used. The fatty acid ester used on the side in contact with the pad fits well to the pad and provides the good lubricating effect to the pad. 2-Ethylhexyl oleate, stearyl laurate, etc., of 10-50 C are used as the fatty acid ester. The coeffts. of friction on the front and rear surfaces of the pad 2 and magnetic head 3 which are entirely different in materials are thereby thoroughly decreased and the wear resistance is thoroughly improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk, and more particularly to a magnetic disk with excellent durability.

[Conventional technology]

-i, a magnetic paint consisting of magnetic powder, a binder component, a solvent, and other necessary components is applied onto a substrate such as a polyester film, dried to form a magnetic layer, and then punched out into a circular shape. Since magnetic disks come into intense sliding contact with magnetic heads and pads during recording and reproduction, the magnetic layers on both the front and back surfaces are likely to be worn out, so there is a need for a disk with excellent durability and little wear.

For this reason, in conventional magnetic disks, various lubricants are mixed into the magnetic layers on both the front and back surfaces.For example, lubricants such as liquid paraffin, higher fatty acids, fatty acid esters, etc. Proposed. (
(Japanese Patent Publication No. 56-20612, Japanese Patent Publication No. 57-51170) [Problems to be Solved by the Invention] However, recording and reproduction of magnetic disks is usually performed using a pad 2 to which a nonwoven fabric 1 is attached, as shown in FIG. and magnetic head 3
This is done by rotating the magnetic disk 4 at high speed with the magnetic disk 4 sandwiched between them, so if the same lubricant is mixed into the magnetic layers on both the front and back sides of the magnetic disk 4, the magnetic heads will be made of completely different materials. However, there is a problem in that it is not possible to exhibit an excellent lubrication effect on both the pad 3 and the pad 2, and the durability of the magnetic disk cannot be sufficiently improved.

[Means for solving problems]

This invention was made as a result of various studies in view of the current situation, and includes an aliphatic compound having an epoxy group or a butoxy group on the magnetic recording surface side of the magnetic disk that contacts the magnetic head, and the opposite side of the magnetic recording surface side is By containing fatty acid ester on the side in contact with the pad, the moisture effect on both the front and back surfaces of the magnetic disk in contact with the magnetic pad and the pad can be sufficiently improved, and the durability of the magnetic disk can be sufficiently improved. It is something that

In this Q, an aliphatic compound having an epoxy group or a butoxy group contained in the magnetic recording surface side of a magnetic disk that contacts the magnetic head has a good affinity for metals. Because of this, it is compatible with metal magnetic heads, exhibits a good lubrication effect on the magnetic head, sufficiently reduces the coefficient of friction of the magnetic layer on the magnetic recording surface side that contacts the magnetic head, and has sufficient wear resistance. improve. Such aliphatic compounds having an epoxy group or a butoxy group have 13 to 5 carbon atoms.
o are preferably used, and for example, butoxyethyl stearate, butyl stearate, etc. are preferably used. The amount used is 0.1 to 0.1 to the magnetic powder.
It is preferably within the range of 10% by weight, preferably 1% to 10fflf; if it is too little, the desired effect cannot be obtained, and if it is too much, it may ooze out onto the surface of the magnetic layer, contaminating the magnetic head, or causing dropouts. There is a risk that this may occur.

In addition, the fatty acid ester used on the side of the magnetic disk that is in contact with the pad opposite to the magnetic recording surface side is compatible with the band and has a good lubricating effect on the pad. The friction coefficient of the magnetic layer or back coat layer on the side opposite to the surface side is sufficiently reduced, and the wear resistance is sufficiently improved. Such fatty acid esters are preferably those having 10 to 50 carbon atoms, such as 2-ethylhexyl oleate, stearyl laurate, cetyl laurate, myristyl laurate, stearyl myristate, and cetyl myristate. Preferred examples include state, myristyl myristate, stearyl palmitate, cetyl palmitate, myristyl palmitate, lauryl palmitate, cetyl stearate, myristyl stearate, lauryl stearate, n-butyl stearate, lauryl myristate, and lauryl laurate. used. When the magnetic layer is on the opposite side of the magnetic recording surface of the magnetic disk, the amount used is 0.01 to 10% by weight, preferably 1 to 10% by weight based on the magnetic powder.
In the case of a back coat layer, it is preferably within the range of 0.1 to 10 weight %, preferably 1 to 10 weight %, based on the total solid components in the back coat Wt.
If it is too small, the desired effect may not be obtained, and if it is too large, it may leak onto the surface of the magnetic layer or back coat layer and contaminate the pad.

In this way, when an aliphatic compound having an epoxy group or a butoxy group is contained on the magnetic recording surface side of the magnetic disk that contacts the magnetic head, and a fatty acid ester is contained on the side that contacts the pad opposite to the magnetic recording surface side, the epoxy The aliphatic compound having a group or butoxy group has a sufficient lubricating effect on the magnetic head, and the fatty acid ester has a sufficient lubricating effect on the pad. The friction coefficient of the front and back surfaces of the magnetic disk rotated at high speed is sufficiently reduced, and the wear resistance is sufficiently improved.

In order to contain an aliphatic compound having an epoxy group or a butoxy group in the magnetic layer formed on the magnetic recording surface side in contact with the magnetic head of such a magnetic disk, it is necessary to incorporate an aliphatic compound having an epoxy group or a butoxy group. The compound is added at the time of preparing the magnetic paint, or this type of aliphatic compound having an epoxy group or butoxy group is dissolved in a suitable solvent such as n-hexane, and a solution 1k obtained by this dissolution is formed in advance. It may be applied or sprayed onto the magnetic layer, or the magnetic layer may be soaked in this solution.

In addition, in order to contain a fatty acid ester in the magnetic layer or back coat layer formed on the side in contact with the pad opposite to the magnetic recording surface side in contact with the magnetic head of the magnetic disk, it is necessary to incorporate the fatty acid ester in the magnetic layer on the magnetic recording surface side described above. As in the case of , this kind of fatty acid ester is added when preparing the magnetic paint or back coat layer paint, or this kind of fatty acid ester is dissolved in a suitable solvent such as n-hexane, and the solution obtained by this dissolution is added. The solution may be coated or sprayed onto a previously formed magnetic layer or back coat layer, or the magnetic layer or back coat layer may be immersed in this solution.

Here, the binder resin used for the magnetic layer or back coat layer formed on both the front and back surfaces of the magnetic disk includes vinyl chloride-vinyl acetate copolymer, polyvinyl butyral resin, polyurethane resin, cellulose resin, and isocyanate. Conventionally widely used binder resins such as compounds are widely used.

Further, as the organic solvent, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, toluene, ethyl acetate, tetrahydrofuran, dimethyl formamide, etc. are used alone or in combination of two or more.

〔Example〕

Next, embodiments of the invention will be described.

Example I α-Fe powder 500 parts by weight Vinyl chloride-vinyl acetate-vinyl 50 Nyl alcohol copolymer polyurethane) 11 fat 30 fat Low molecular weight isocyanate compound 20・tA1□03 approx. 1□
50...butoxyethyl stearate 1.
20〃2-Ethylhexyl oleate 201
/ Cyclohexanone 650 Toluene 650 This composition was mixed in a ball mill for 72 hours to prepare a magnetic paint. This magnetic paint was applied to the magnetic recording surface side of a polyester film with a thickness of 30 μm, dried to form a magnetic layer with a dry thickness of 4 μm, and calendered. In addition, a magnetic paint was prepared in the same manner as above except that butoxyethyl stearate was omitted from the composition of the magnetic paint, and this was applied to the opposite side of the magnetic recording surface of the polyester film, and dried to a dry thickness of 4 μm. A magnetic layer was formed and calendered. Afterwards, they were punched out into disk shapes to create magnetic disks.

Comparative Example 1 A magnetic disk was produced in the same manner as in Example 1, except that the same magnetic layer as that formed on the magnetic recording surface side of the polyester film was formed on the side opposite to the magnetic recording surface side of the polyester film.

Comparative Example 2 A magnetic disk was produced in the same manner as in Example 1, except that the same magnetic layer was formed on the magnetic recording surface side of the polyester film on the side opposite to the magnetic recording surface side.

The durability of the magnetic disks obtained in each example and comparative example was tested. In the durability test, the obtained magnetic disk was mounted on a drive unit rotating at 3600 rpm at room temperature of 20°C and 160% RH, and was rotated at a relative speed of 7.5 m/sec for 24 hours.
The decrease in output after continuous running for a certain period of time was measured, and the presence or absence of head dirt, pad dirt, and scratches on the magnetic disk was observed.

The table below shows the results.

Table [Effects of the Invention] As is clear from the above table, the magnetic disk obtained in Comparative Example 1 had severe pad lη wear and scratches were observed on the back side of the magnetic disk, and the magnetic disk obtained in Comparative Example 2 The magnetic disk had head dirt and scratches on the magnetic recording surface side of the magnetic disk, whereas the magnetic disk obtained in Example 1 had no head dirt, pad dirt, or disk scratches. In addition, while the magnetic disks obtained in Comparative Examples 1 and 2 had a decrease in output, the magnetic disk obtained in Example 1 did not have a decrease in output, which indicates that the magnetic disk obtained by the present invention has good durability. It can be seen that it is excellent.

[Brief explanation of drawings]

FIG. 1 is an enlarged sectional view of a main part of a recording/reproducing apparatus used for recording/reproducing information on a magnetic disk. Patent applicant Hitachi Maxell Ltd. 1st leap

Claims (1)

[Claims] 1. The magnetic recording surface side of the magnetic disk that contacts the magnetic head contains an aliphatic compound having an epoxy group or a butoxy group, and the side opposite to the magnetic recording surface side that contacts the pad contains a fatty acid ester. magnetic disk