JPS61214220A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide good lubricity to a magnetic layer formed of magnetic powder and binder as essential components and to improve the durability thereof by incorporating a specified ester compd. into the magnetic layer. CONSTITUTION:The magnetic layer of a magnetic recording medium is formed essentially of the magnetic powder and binder. The magnetic layer is formed by containing the ester compd. specified by the formula. In the formula, R1, R2 are satd. alkyl group having the straight chain or branched chain of 1-19C in which the sum of the number of carbon atoms of R1 and R2 is made 20 and R3 is a satd. alkyl group having the straight chain or branched chain of which the number of carbon atoms are made 19-27C. The good lubricity is thus provided to the magnetic recording medium and the durability of the medium is improved. The bleeding from the magnetic layer is prevented.

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, binding 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 it is a companion, 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 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.

(In the formula, R3 and R2 are linear or branched saturated alkyl groups having 1 to 19 carbon atoms (however, the sum of the carbon numbers of R1 and R2 is 20); R3 is a linear or branched alkyl group having 19 to 27 carbon atoms; (It is a saturated alkyl group having a branch.) [Function] The ester compound represented by the general formula +11 according to the present invention is very limited, and the portion derived from alcohol is a branched alcohol having 22 carbon atoms. It must be. In addition, the number of carbon atoms in the part derived from fatty acids is 20 to 2.
It is necessary to be in the range of 8. It is not clear why the durability 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 although they have good lubricity at relatively high temperatures, they have poor fluidity and permeability at low temperatures, such as 5°C, and are not good for media at low temperatures. It was not possible to provide sufficient durability.

Inferred from the above, branched esters have lower melting points even if they have the same molecular weight as non-branched esters, and this is why they impart good lubricity to magnetic recording media. This is thought to improve durability as a result.

The ester compound according to the present invention can be obtained by an esterification reaction using a branched alcohol having 22 carbon atoms and a -basic fatty acid having 20 to 28 carbon atoms. The branched alcohol used here is called Guerbet alcohol because of its synthesis method.

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, -1, 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 rP.
Metal oxides such as ezOx, Fea04, Crow, and also Co-deposited 7-Fez03, Co-doped r-Fe
r-Fe203 processed like ZOz, iron metal powder, barium ferrite in the form of microplates, and some of its Fe atoms are 1 such as Tin Cot Zn+ V+ Nb, etc.
Magnetic powder substituted with species or two or more species, Co, Pe-C
o, ultrafine powder of metal or alloy such as Fe-Ni, etc. Among these, iron metal powder has particularly poor chemical stability, so in order to improve this, nickel, cobalt, titanium,
Silicon, aluminum, etc. may be added in small amounts in the form of metal atoms, salts, and oxides, or may be surface treated, and these may 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 4 Using the lubricants shown in Table 1, mixtures having the compositions shown below were prepared.

CO adhesion - FEiz (h 100 parts by weight PVC/vinyl acetate copolymer) 30 Nitrile butadiene rubber 2 15 Carbon black 7 Aluminum oxide 6 Toluene 150 Methyl ethyl ketone 150 Lecithin 1 Lubricant 6 Note) *1 US U, C, C0 company Product name: VAGH*2
1432J (trade name, manufactured by Nippon Zeon Co., Ltd.) Next, the carcass compound was kneaded in a sand mill for 15 hours, and then a polyisocyanate compound (Coronate manufactured by Nippon Polyurethane) was kneaded for 15 hours.
A total of four 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.

The durability of each magnetic disk was tested by loading these disks into a floppy disk accelerated durability test drive and measuring the running time at 5°C and 25°C until the playback output reached 70% of the initial output. I judged it. The results are shown in Table 1.

Table 1 ■ 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 described above.

Magnetic disks were manufactured using these paints in the same manner as in Example 1, and the durability of these disks was evaluated. 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 (1). magnetic recording media. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(1) (In the formula, R_1 and R_2 are carbon numbers 1 to 19 (however, R
The sum of the carbon numbers of _1 and R_2 is 20), a saturated alkyl group having a straight chain or a branch, and R_3 has 19 to 27 carbon atoms.
It is a saturated alkyl group having a straight chain or a branch. )