JPS621118A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide good lubricity to a magnetic layer and to improve the durability thereof even under broad using environments by incorporating a specific ester compd. into the magnetic layer. CONSTITUTION:The magnetic layer of the magnetic recording medium having the magnetic layer contg. magnetic powder and binder as essential components contains the ester compd. expressed by the formula. The ester compd. expressed by the formula is obtd. by the esterification reaction using branched alcohol of 20-34C and unsatd. fatty acid of 8-28C. The branched alcohol used therein refers to the alcohol known as Guerbet alcohol from the method for synthesizing the same and the unsatd. fatty acid used therein is exemplified by a decylenic acid, etc. The magnetic powder is exemplified by fine metallic oxides of a needle-like shape such as gamma-Fe2O3, Fe3O4 and CrO2.

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 the media, while fatty acids such as stearate 4nonic acid and oleic acid, and hydrocarbon-based lubricants such as liquid paraffin, do not improve the durability of the media. Although it is effective in improving magnetic properties, it has disadvantages such as poor compatibility with the binder (and if 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 containing magnetic powder and a binder as main components, wherein the magnetic layer contains an ester compound represented by the following general formula (1). It provides a recording medium.

υ (In the formula, R1 and R2 each have 1 to 25 carbon atoms (however, R
, and R2 have a total number of carbon atoms of 18 to 32), and R3 is an unsaturated hydrocarbon group having 7 to 27 carbon atoms. ) [Function] The ester compound represented by the general formula (1) according to the present invention is a certain limited compound, and the part derived from alcohol is a branched alcohol having 20 to 34 carbon atoms, and the part derived from alcohol is a branched alcohol having 20 to 34 carbon atoms. The derived moiety must be an unsaturated basic fatty acid having 8 to 28 carbon atoms. It is not clear why the lubricity of magnetic recording media is greatly improved when such specific ester compounds are used as lubricants.

According to the studies conducted by the present inventors, ester-based lubricants are optimal in terms of compatibility with binders, and lubricants with relatively large molecular weights are more effective in improving lubricity. . However, many ordinary esters with large molecular weights have high melting points and have good lubricity at relatively high temperatures, but have poor fluidity and permeability at low temperatures, such as 5°C. It was not possible to provide good durability. Judging from the above, due to the synergistic effect of branched alcohol and unsaturated fatty acids,
It is presumed that the melting point of the ester compound according to the present invention is lowered, thereby imparting good lubricity to the magnetic recording medium and improving durability.

The ester compound according to the present invention can be obtained by an esterification reaction using a branched alcohol having 20 to 34 carbon atoms and an unsaturated fatty acid having 8 to 28 carbon atoms. The branched alcohol used here is called Guerbet alcohol because of its synthesis method. Further, examples of the unsaturated fatty acids used here include decylenic acid, undecylenic acid, matucolaic acid, palmitoleic acid, oleic acid, linoleic acid, lylunic acid, arachidonic acid, erucic acid, nerponic acid, and the like.

Among these ester compounds, those having a total number of carbon atoms of 30 or more are preferred.

The ester compound of 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. Furthermore, a conventional lubricant may be added to the ester compound of the present invention.

The magnetic powder according to the present invention is fine needle-shaped rF.
metal oxides such as eJ*, Fe3O4, Crot,
In addition, Co-deposited r-FezO=, Co-doped r-Fez
Magnetism in which γ-Fe, O, iron metal powder, barium ferrite in the form of microplates, and some of its Fe atoms are replaced with one or more of Ti, Co+Zn+V+Nb, etc., which have been subjected to processing treatments such as Ox Powder, Co+ Fe-Co, Pe
Examples include ultrafine powder of metals or alloys such as -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 ester compound represented by the general formula (1) 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 11 Using the lubricants shown in Table 1, mixtures having the compositions shown below were prepared.

Co-adhered r-Fez03 100 parts by weight PVC/acetic acid picopolymer 30 Nitrile butadiene rubber 15 Carbon black 7 Aluminum oxide 6 Toluene 150 Methyl ethyl ketone 150 Lecithin l Lubricant 6 Note) *l Manufactured by U.S.A. Product name: VAG
H Book 2 Trade name 1432J manufactured by Nippon Zeon Co., Ltd. Next, the above mixture was kneaded in a sand mill for 15 hours, and then 7 parts by weight of a polyisocyanate compound (Coronate L manufactured by Nippon Polyurethane ■) was added to prepare a total of 11 types of magnetic paint. did. Next, these paints were applied onto a polyethylene terephthalate film having a thickness of 75 μm to a dry film thickness of 1.5 μm, and after drying, calendering 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.

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

Table 1 Comparative Examples 1 to 6 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, and the method of the example was carried out. A total of six 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, characterized in that the magnetic layer contains an ester compound represented by the following general formula (1). magnetic recording media. ▲There are mathematical formulas, chemical formulas, tables, etc.▼・・・・・・(1) {In the formula, R_1 and R_2 each have 1 to 25 carbon atoms (however, the sum of the carbon numbers of R_1 and R_2 is 18 to 32). The linear or branched saturated alkyl group, R_3, is an unsaturated hydrocarbon group having 7 to 27 carbon atoms. }