JPS62125533A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide the excellent lubricity to the titled medium and to improve the durability under extensive service conditions by incorporating an ester compd. shown by the specified general formula and squalene into a magnetic layer. CONSTITUTION:From 1-15wt% of the ester compd. based on general formula I and squalene such as 2,6,10,15,19,23-hexamethyltetracosane is incorporated into magnetic powder to form the magnetic layer. Lubricity is provided to the magnetic recording medium using this magnetic layer and the durability is enhanced under the extensive service conditions. In the formula, R1 and R2 are a 1-25C (where the total number of carbons in R1 and R2 is 14-34) straight-chain or branched-chain saturated alkyl group nd R3 is a 7-29C straight-chain or branched-chain saturated or unsaturated alkyl group.

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 made by coating a magnetic paint consisting of magnetic powder, binder resin, organic solvent, and other necessary components on 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, 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 nonmagnetic support and a magnetic layer thereon, in which the magnetic layer has the following general formula (I) (wherein R2 and R2 have a carbon number of 1 to 25 (wherein R .

and R2 have a total of 14 to 34 carbon atoms), and R3 is a linear or branched saturated or unsaturated alkyl group having 7 to 29 carbon atoms.

) and squalane.

[Function] The magnetic recording medium of the present invention has the general formula (I) in the magnetic layer.
) and squalane. These ester compounds and squalane are thought to act as lubricants. When these are used in combination, excellent lubricity is imparted, but the detailed reason for this is not clear.

The ester compound represented by the general formula (I) according to the present invention can be produced by, for example, an esterification reaction between a branched alcohol (this branched alcohol is called Guerbet alcohol because of its synthesis method) and a fatty acid. Obtainable. In the present invention, as described above, esters in which the sum of the carbon numbers of R1 and R2 is 14 to 34 are used, and those in which the sum of carbon numbers is 22 to 34 are particularly preferred.

Squalane according to the present invention is a hydrocarbon represented by the following formula (II), and is 2.6.10,15,19.23-
Also called hexamethyltetracosane.

Further, the total amount of the ester compound and squalane used in the present invention is usually 1 to 100 parts by weight of magnetic powder.
It is 15 parts by weight. In addition, the weight ratio of the ester compound and squalane is usually ester compound/squalane-1.
Although the ratio is 0/90 to 90/10, it is preferable to use squalane in a slightly larger amount than the ester compound.

The magnetic powder according to the present invention is fine needle-shaped r-Fe.
20. , Fe1Oa, metal oxides such as Cr0z,
Also, Co-coated T-F, e203, Co-doped 7-Fe2
T-Fe203 processed like O, iron metal powder, barium ferrite in the form of microplates, and some of its Fe atoms are one or more of Ti, Go, Zn, V, Nb, etc. Substituted magnetic powder, Co, Fe-Co, Pe
Examples include ultrafine powder of metals or alloys such as -Ni. These ferric metal powders have particularly poor chemical stability, so to improve this, small amounts of nickel, cobalt, titanium, silicon, aluminum, etc. in the form of metal atoms, salts, and oxides are added or surface treated. However, these can also be used. In order to stabilize iron metal powder, a thin oxide film is sometimes formed on the surface in a weakly oxidizing atmosphere, and metal powder treated in this way can 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.

The blending amount of the binder is 15 to 60 parts by weight per 100 parts by weight of magnetic powder per ship. 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.

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

Co-coated T-Feze 3100 parts by weight PVC/vinyl acetate copolymer 2' 30 Nitrile butadiene rubber 15 parts by weight Carbon black 7 Aluminum oxide 6 Toluene 150 Methyl ethyl ketone 150 Lecithin 1 Lubricant 8 Note) d United States U, C, 'C, Inc. Product name: VAG
8 pieces 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 7 parts by weight of a polyisocyanate compound (trade name: Corone L, manufactured by Nippon Polyurethane ■) was added to prepare a total of five types of magnetic paints. These paints were then applied onto a 75μ thick polyethylene terephthalate film to a dry film thickness of 1.
It was applied to a thickness of 5 μm, and after drying, it was calendered. 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 3 Instead of the lubricant used in the example, 8 parts by weight of the various lubricants shown in Table 2 were used, the other components and their amounts were the same as in the example, and the method of the example was followed. A total of three types of magnetic paints were prepared accordingly. Magnetic disks were manufactured using these paints in the same manner as in the examples, and the durability of these disks was examined. The results are shown in Table 2.

Table 2

Claims (1)

[Claims] 1. In a magnetic recording medium having a magnetic layer on a non-magnetic support, the magnetic layer has the following general formula (I) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼... I) {In the formula, R_1 and R_2 have a carbon number of 1 to 25 (however, R
The sum of the carbon numbers of _1 and R_2 is 14 to 34) is a linear or branched saturated alkyl group, and R_3 is a saturated alkyl group having 7 to 7 carbon atoms.
It is a saturated or unsaturated alkyl group having 29 straight or branched chains. } A magnetic recording medium characterized by containing an ester compound represented by these and squalane.