JPS6260124A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To render good lubricity to a magnetic recording medium and to improve the durability thereof by incorporating a branched alcohol deriv. having specific structure as a lubricating agent into a magnetic layer. CONSTITUTION:The branched alcohol deriv. expressed by the formula is incorporated as the lubricating agent into the magnetic layer essentially consisting of magnetic powder and binder. In the formula, R1, R2 are alcohol group of 1-20C and the total of the number of carbon atoms of R1 and R2 is 7-30, (n) is 1-4 integer, (m) is 1-25 integer. The branched alcohol deriv. is a compd. prepd. by adding an ethylene oxide, propylene oxide or butylene oxide to branched alcohol and may be added into a magnetic coating compd. or may be sprayed on the magnetic coated film after the deriv. is dissolved in a solvent. The compounding ratio of the binder is 15-60pts.wt. by 100pts.wt. magnetic powder and the compounding ratio of the branched alcohol deriv. is made 1-15pts.wt.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to magnetic recording media. Specifically, the present invention relates to a magnetic recording medium with excellent durability.

[Conventional technology and problems]

Magnetic recording media are generally made by applying magnetic paint consisting of magnetic powder, binder resin, organic solvent, and other necessary components onto a substrate such as polyester film. Since the magnetic layer is easily abraded due to violent sliding contact with the head, jacket liner, etc., there is a need for a magnetic layer that is less abrasive and has excellent durability.

Therefore, as a measure to improve the wear resistance of the magnetic layer, various lubricants are mixed into the magnetic layer.

Conventionally used lubricants include fatty acids, oleyl oleate, butoxide stearate, fatty acid amides, liquid paraffin, wax, and the like. however,
At present, these lubricants cannot be said to be satisfactory in terms of performance. For example, oleyl oleate, butoxide stearate, etc. are insufficient for improving the durability of media, while fatty acids such as stearic acid and oleic acid, and hydrocarbon-based lubricants such as liquid paraffin are effective in improving durability. Although effective, it has poor compatibility with the binder, and when used in large quantities, it bleeds from the surface of the magnetic layer and tends to stain the head.

[Means for solving problems]

The present inventors have arrived at the present invention as a result of intensive research in order to obtain a magnetic recording medium that is imparted with good lubricity and has significantly improved durability even under a wide range of usage environments.

That is, the present invention provides a magnetic recording medium having a magnetic layer mainly composed of magnetic powder and a binder, characterized in that the magnetic layer contains a branched alcohol derivative represented by the following general formula (I). A magnetic recording medium is provided.

(In the formula, R1 and h are each an alkyl group having 1 to 20 carbon atoms, but the total number of carbon atoms of R and R2 is 7 to 30. n is an integer of 1 to 4, and m is an integer of 1 to 25. ) [Function] The branched alcohol derivative represented by the general formula (I) according to the present invention is a compound obtained by adding ethylene oxide, propylene oxide or butylene oxide to a branched alcohol.

This branched alcohol is called Guerbet alcohol because of its synthesis method. R, and R2 of this derivative are each an alkyl group having 1 to 20 carbon atoms, but the total number of carbon atoms must be 7 to 30. Further, the number of moles added of ethylene oxide, etc. is 1 to 25, and preferably 1 to 10.

The branched alcohol derivative according to the present invention may be used by being added to a magnetic coating, or may be dissolved in a suitable solvent and sprayed onto a magnetic coating.

Moreover, in addition to this derivative, the above-mentioned ordinary lubricants may be added.

The magnetic powder according to the present invention is fine needle-shaped rF.
Metal oxides such as ezO1, Pe3t4, Crag,
Also, Co-coated r-Fe, 03, Co-doped r-Fet
γ-Fe processed like O=, 03, iron metal powder, microplate-shaped barium ferrite and some of its Fe atoms are Ti+ Co + Z n + V + N
Magnetic powder substituted with one or more of b, etc., Co,
Examples include ultrafine powder of metals or alloys such as Fe-Co and Fe-Ni. Among these, iron metal powder has particularly poor chemical stability, so to improve this, small amounts of nickel, cobalt, titanium, silicon, aluminum, etc. are added in the form of metal atoms, salts, and oxides, or the surface is treated. but,
These can also be used. In order to stabilize iron metal powder, a thin oxide film may be formed on the surface in a weakly oxidizing atmosphere, and metal powder treated in this manner may also be used.

Examples of binders that can be used in the present invention include polyurethane, polyester, polyvinyl chloride,
Vinyl chloride vinyl acetate copolymer, polyacrylonitrile, nitrile rubber, epoxy resin, alkyl resin, polyamide, polyacrylic acid ester, polymethacrylic acid ester, polyvinyl acetate, polyvinyl butyral, vinylidene chloride, vinylidene chloride copolymer, Examples include nitrified cotton, maleic acid-modified vinyl chloride/vinyl acetate copolymer, and ethyl cellulose.

Although these may be used alone, two or more types are usually used in combination. Furthermore, a plasticizer or a hardening agent may be added to adjust the hardness of the resin.

Further, the amount of the binder blended is generally 15 to 60 parts by weight per 100 parts by weight of the magnetic powder. Even if the binder has the highest binding strength, if the amount is less than 15 parts by weight, the strength of the magnetic coating will be weak and the adhesive strength between the substrate and the magnetic coating will be insufficient. On the other hand, if the amount is more than 60 parts by weight, the concentration of magnetic powder in the magnetic coating film becomes small, which is disadvantageous because the reproduction output decreases. Furthermore, the properties of the coating film may deteriorate.

Further, the branched alcohol derivative represented by the general formula (I) is usually used in an amount of 1 to 15% by weight based on the magnetic powder.

〔Example〕

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

Examples 1 to 7 Using the lubricants shown in Table 1, mixtures having the compositions shown below were prepared.

Co adhesion r -Fe20i 100 parts by weight PVC/acetic acid picopolymer*1 30 Nitrile butadiene rubber 15 Carbon blank 7 Aluminum oxide 6 Toluene 150 Methyl ethyl ketone 150 Lecithin 1 Lubricant 6 Note) Umbrella 1 Manufactured by U, C, C, USA Product name VAGH book 2
Product name 1432J manufactured by Nippon Zeon Co., Ltd. Next, the above mixture was kneaded in a sand mill for 15 hours, and then a polyisocyanate compound (Coronate L manufactured by Nippon Polyurethane ■) was added.
A total of 7 types of magnetic paints were prepared by adding 7 parts by weight of . Next, these paints were applied onto a polyethylene terephthalate film having a thickness of 75 μm so that the dry film thickness was 1.5 μm, and after drying, a calender treatment was performed. Further, this was left at 60° C. for 4 days to undergo a hardening reaction, and then punched out into a disk shape and surface polished to produce a magnetic disk.

By loading these disks into a floppy disk accelerated durability test drive and measuring the running time at 5°C until the playback output reaches 70% of the initial output,
The durability of each magnetic disk was determined. The results are shown in Table 1.

Comparative Examples 1 to 4 The method of Example-1 was carried out by using 6 parts by weight of various lubricants shown in Table 2 instead of the lubricants used in Examples, and keeping the other components and amounts the same as in Example 1. A total of four types of magnetic paints were prepared according to the method.

Magnetic disks were manufactured using these paints in the same manner as in Example 1, and the durability of these disks was examined. The results are shown in Table 2.

Table 2

Claims (1)

[Claims] 1. A magnetic recording medium having a magnetic layer mainly composed of magnetic powder and a binder, wherein the magnetic layer contains a branched alcohol derivative represented by the following general formula (I). Features of magnetic recording media. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) (In the formula, R_1 and R_2 are each an alkyl group with 1 to 20 carbon atoms, but the total number of carbon atoms of R_1 and R_2 is 7.
~30. n is an integer of 1 to 4, and m is an integer of 1 to 25. )