JPS6289224A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the lubricity of a magnetic layer with a head by incorporating a specific ester compd. into the magnetic layer. CONSTITUTION:The ester compd. expressed by the formula is obtd. by the esterification reaction of the compd. obtd. by adding 1-25mol lower alkylene oxide to secondary alcohol of 4-28C in total and fatty acid of 6-24C. The hydrocarbon group of R1-R3 in the ester compd. may be straight chain, branched, satd. or unsatd. The number of moles to be added of the lower alkylene oxide in the ester compd. is preferably 1-10 and further the total of carbon atoms of R1 and R2 is preferably >=12. The lubricity is thereby improved.

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 coating a magnetic paint consisting of magnetic powder, binder resin, organic solvent, and other necessary components onto a substrate such as a polyester film. Since the magnetic layer is easily abraded due to violent sliding contact with the magnetic 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, Fuchs, 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]

As a result of intensive research to solve the above-mentioned problems, the present inventors discovered a magnetic recording medium that has excellent lubricity with the head and does not bleed lubricant, and has completed the present invention.

That is, the present invention provides a magnetic recording medium having a magnetic layer containing magnetic powder and a binder as main components, wherein the magnetic layer contains an ester compound represented by the following general formula (I). It provides a recording medium.

(In the formula, R5 and R2 are hydrocarbon groups having 2 to 14 carbon atoms, R
3 represents a hydrocarbon group having 5 to 23 carbon atoms, n represents an integer of 2 to 4, and m represents an integer of 1 to 25. ) [Function] The ester compound represented by the general formula (I) according to the present invention is a compound obtained by adding 1 to 25 moles of lower alkylene oxide to a secondary alcohol having a total of 4 to 28 carbon atoms; It can be obtained by an esterification reaction with a fatty acid having 6 to 24 carbon atoms.

In the ester compound, the hydrocarbon groups of R6, R2 and R3 may be linear, branched, saturated or unsaturated. Among these ester compounds, those having a lower alkylene oxide addition mole number of 1 to 10 are preferable, and those in which the total number of carbon atoms of R1 and R2 is 12 or more are more preferable.

The ester compound of the present invention may be used by being added to a magnetic coating, or it may be dissolved in a suitable solvent and sprayed onto a magnetic coating. Further, the ester compound of the present invention and the above-mentioned ordinary lubricants may be used together.

The magnetic powder according to the present invention is fine needle-shaped rF.
Metal oxides such as e, 03, Fe50*, CrO2, as well as Co-coated r-Fezol, Co-doped T-Fe
,0. γ-Fez03, iron metal powder, barium ferrite in the form of microplates, and some of its Fe atoms are one or two of Ti, Co, Zn, V, Nb, etc.
Magnetic powder substituted with more than one species, Co, Fe-C (I+
Examples include ultrafine powder of metal or alloy such as 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. However, 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, alkyd resin, polyamide, polyacrylic acid ester, polymethacrylic acid ester, polyvinyl acetate, polyvinyl butyral, vinylidene chloride, vinylidene chloride copolymer, nitrified cotton , maleic acid-modified vinyl chloride/vinyl acetate copolymer, ethyl cellulose, and the like.

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 amount of the ester compound represented by the general formula (I) used is preferably 0.1 to 25% by weight based on the binder.

〔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 6 Using the lubricants shown in Table 1, mixtures having the compositions shown below were prepared.

CO-adhered r-Fez03 100 parts by weight PVC/vinyl acetate copolymer 1130 Nitrile butadiene rubber 0 15 Carbon black 7 Aluminum oxide 6 Toluene 150 Methyl ethyl ketone 150 parts by weight Lubricant
6 Note) *1 Manufactured by U, C, C, USA, product name: VAGH Umbrella 2
The above mixture was kneaded in a sand mill for 15 hours, manufactured by Nippon Zeon Co., Ltd. (trade name: Hiker), and then a polyisocyanate compound (Coronate L manufactured by Nippon Polyurethane Industries)
) was added to prepare a total of six types of magnetic paints.

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.

Table 1 Note) * Comparative Examples 1 to 4 In place of the lubricant used in the example, 6 parts by weight of the various lubricants shown in Table 2 were used, and the other components and their amounts were the same as in Example 1. A total of four types of magnetic paints were prepared according to the method of Example 1.

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.

Claims (1)

[Claims] 1. A magnetic recording medium having a magnetic layer mainly composed of magnetic powder and a binder, characterized in that the magnetic layer contains an ester compound represented by the following general formula (I). magnetic recording media. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(I) (In the formula, R_1 and R_2 are hydrocarbon groups with 2 to 14 carbon atoms, R_3 is a hydrocarbon group with 5 to 23 carbon atoms, and n is 2
An integer of ~4, m represents an integer of 1 to 25. 2. The magnetic recording medium according to claim 1, wherein in the general formula (I), m is an integer of 1 to 10. 3. In general formula (I), the total number of carbon atoms of R_1 and R_2 is 12 or more, claim 1 or 2
Magnetic recording medium described in Section 1.