JPS6150214A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve durability by providing a magnetic layer contg. gallic ester consisting of gallic acid and higher aliphat. alcohol of >=12C and higher fatty acid ester consisting of propylene glycol or glycerol and higher fatty acid. CONSTITUTION:The gallic ester consisting of gallic acid and higher alcohol of >=12C and the higher fatty acid ester consisting of propylene glycol or glycerol and higher fatty acid are compounded. The mixture thereof is dissolved in a suitable solvent and the soln. is coated or sprayed on the preliminarily formed magnetic layer or the magnetic layer is immersed in said soln. The decrease in the lubricity on the surface of the magnetic layer is obviated even after long- term use, by which the running thereof is improved and the durability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording medium, and in particular provides a magnetic recording medium with improved surface lubricity and excellent durability.

Conventional configurations and their problems Traditionally, magnetic recording media have been in violent sliding contact with magnetic heads and pads during recording and reproduction, and the magnetic layer is easily worn out, so highly durable media with excellent surface lubricity have been desired. ing. Therefore, in order to improve the durability of magnetic recording media, various lubricants have been mixed or coated into the magnetic layer. Liquid paraffin is used as a lubricant for these.

Higher fatty acids, higher fatty acid esters, etc. are used.

These lubricants certainly improve the durability of magnetic recording media, but they are not yet sufficient.Objective of the InventionThe present invention has discovered a lubricant that is superior to conventionally used lubricants, and has improved the durability of magnetic recording media. The purpose of the present invention is to improve and stabilize the surface lubricity of the medium and provide a magnetic recording medium with significantly improved durability.

Structure of the Invention In order to achieve this object, the present invention provides gallic acid esters consisting of gallic acid and a higher aliphatic alcohol having 12 or more carbon atoms, propylene glycol or glycerin, and higher fatty acid esters consisting of higher fatty acids. By having a magnetic layer containing at least one type of each type, the durability of the magnetic recording medium is greatly improved.

The gallic acid esters used in the present invention include gallic acid lauryl ester, gallic acid myristyl ester,
Examples include gallic acid palmityl ester, gallic acid stearyl ester, gallic acid oleyl ester, and the like.

Examples of esters made of propylene glycol or glycerin and higher fatty acids include propylene glycol monomyristate, propylene glycol monopalmitate, propylene glycol monostearate, propylene gelicol monooleate, and propylene glycol distearate.

Examples include glyceryl monomyristate, glyceryl monopalmitate, glyceryl monostearate, glyceryl distearate, glyceryl tristearate, and glyceryl monooleate.

These have excellent lubricity and are sufficiently effective even when used alone; however, when only gallic acid esters are used, the surface frictional resistance becomes slightly high. However, by combining propylene glycol monofatty acid esters, the surface friction resistance is also reduced and a great effect on durability can be obtained.

The blending ratio of gallic acid esters and fatty acid esters of propylene glycol or glycerin is preferably 20% or more by weight of the fatty acid esters of propylene/glycol or glycerin relative to the gallic acid esters, and if it is less than that, no effect will be obtained. I can't do it. A mixture of these esters can be used in combination with a conventionally used lubricant, thereby further improving the durability of the magnetic layer. The lubricants used in combination are lauric acid and myristic acid, which have excellent lubricity.

Fatty acids with 12 or more carbon atoms such as palmitic acid, stearic acid, abietic acid, montanic acid, higher aliphatic alcohols with 12 or more carbon atoms such as lauryl alcohol, myristyl alcohol, stearyl alcohol, unsaturated fatty acids such as oleic acid, stearic acid -n-propyl, n-butyl stearate, n-amyl stearate,
Fatty acid esters such as n-butyl laurate, octyl palmitate, stearyl stearate, intridemyl stearate, ethyl oleate, dioleyl adipate, and dioleyl phthalate.

Hydrocarbon lubricants such as liquid halafine, squalane, squalene, α-olefin polymerized oil, silicone lubricants such as dimethyl silicone oil, methylphenyl silicone oil, 70-mouth silicone oil, modified silicone compounds, perfluoroalkyl polyether, Examples include fluorine-based lubricants such as fluorinated alkyl esters. These are usually used alone or in combination, and the amount used is preferably 5 to 3Q parts in total with gallic acid esters, propylene glycol, or glycerin fatty acid esters; too little will have no effect, and too much will cause magnetic properties. Bleed-out to the surface of the layer becomes severe, spoiling the appearance and
This may also cause contamination of the magnetic head.

When using the above lubricant as a lubricant for magnetic recording media, it can be dissolved in a suitable solvent, etc., and applied or sprayed onto a pre-formed magnetic layer, or the magnetic layer can be immersed in the above solution. It can be done by immersion. Alternatively, these may be kneaded together with magnetic powder, binder resin, and other additives to prepare a magnetic ink, and a magnetic layer may be formed on a polyester film or the like. Alternatively, the binder resin and these lubricants may be kneaded, diluted with a suitable solvent, and applied very thinly to a previously formed magnetic layer.

Description of examples Examples of the present invention will be described below.

Example 1 Magnetic powder C〇-containing 1-Fe203 250 parts by weight VAGH (vinyl chloride-vinyl acetate-vinyl alcohol copolymer manufactured by U.C.C., USA) 82 parts by weight N-230
4 (Polyurethane manufactured by Nippon Polyurethane Industry Co., Ltd.) 18 parts by weight Coronate L (Polyurethane manufactured by Nippon Polyurethane Industry Co., Ltd.) 7.5
Parts by weight Granular a-A (320312, 5 parts by weight Carbon black 15 parts by weight Methyl ethyl ketone 50 parts by weight Toluene
Samples 1 to 2 in Table 1 to a composition of 600 parts by weight or more
A magnetic ink was prepared by blending lubricants in the proportions shown in 6 and kneading them in a ball mill, which was applied to both sides of a 5 μm thick polyester film to a dry thickness of 2.0 μm, and after drying was calendered. After it hardens, it is punched out into a disk. Both sides of this disk were further polished to make it smoother to produce a magnetic disk.

Example 2 N-2304 (polyurethane manufactured by Nippon Polyurethane Industries Co., Ltd.) 20 parts by weight VAGH
(Vinyl chloride-vinyl acetate-vinyl alcohol copolymer manufactured by U, C, C, USA) 75 parts by weight Coronate L (Japan Polyureta 1, polyisomyanate manufactured by Kogyo Co., Ltd.)
6 parts by weight microhexanone
300 parts by weight methyl ethyl ketone 1
00 parts by weight or more of the composition was blended with lubricants in the proportions shown in Samples 3o to 37 in Table 2, and this was shaken with a paint conditioner (manufactured by Red Devil) for 2 hours to prepare a paint.

By sputtering, cobalt-chromium alloy is deposited to a thickness of 0.
Formed on a polyester film to a thickness of 5 μm,
A magnetic disk was produced by punching it into a disk shape, and the above paint was applied to the disk to a thickness of 0.2 μm using a spin coating method.

Comparative Example 3 Similar to Example 1, conventionally used fatty acids,
A magnetic disk was fabricated using liquid paraffin as a lubricant. The formulations are shown in Samples 27 to 29 in Table 1.

Comparative Example 4 Similarly to Example 2, a magnetic disk was produced using conventionally used fatty acids and liquid paraffin as lubricants. The formulations are shown in samples 38 and 39 in Table 2.

In order to examine the durability of the magnetic disks obtained in Examples and Comparative Examples, each magnetic disk was housed in a polyvinyl chloride jacket lined with nonwoven fabric, loaded into a recording and reproducing device, and the reproduced output was observed.

Example 1. The recording/reproducing device used to evaluate the durability of the magnetic disk obtained in Comparative Example 1 had a head pressure of 20 Kf/a.
l, and the circumferential speed is 1.5 m/sec. Ability 1 example 2. For the magnetic disk obtained in Comparative Example 2, the head pressure was 30? /crA, and the circumferential speed is 1.5 m/s e
It is c. A recording/reproducing device loaded with a magnetic disk was operated under each condition, and the output drop, occurrence of dropout, and staining of the magnetic head after a certain period of time were examined. The results are shown in Table 31 and Table 4.

As is clear from Table 39 and Table 4 below, gallic acid varnish 1
Type 7'' and 2°oevyfυ''-'' are magnetic disks that do not contain fatty acid esters of gutzunone and sample 2.
No. 7 to No. 29, No. 38, and No. 39 had a severe reduction in reproduction output due to abrasion of the magnetic layer, and there were many occurrences of knock-out. On the other hand, the device according to the present invention has excellent durability, with most of the reductions in playback output being 10% or less.

Effects of the Invention As described above, according to the present invention, it is possible to obtain a magnetic recording medium with excellent durability and stable running, with no reduction in the lubricity of the surface of the magnetic layer even after long-term use.

Claims (1)

[Claims] It is characterized by having a magnetic layer containing at least one each of gallic acid esters consisting of gallic acid and a higher aliphatic alcohol having 12 or more carbon atoms, propylene glycol or glycerin, and higher fatty acid esters consisting of higher fatty acids. magnetic recording media.