JPS61214221A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having improved lubricity and durability by incorporating a prescribed ester compd. into a magnetic layer consisting essentially of magnetic powder and binder. CONSTITUTION:The ester compd. expressed by the general formula I is incorporated into the magnetic layer consisting essentially of the magnetic powder and binder. In the formula, R1, R2 are a satd. alkyl group having a straight chain or branched chain of 1-19C (where the sum of the carbon atoms of R1 and R2 is 20), R2 is a satd. alkyl group having a straight chain or branched chain of 7-15C. The part derived from the alcohol of such ester compd. is the branched alcohol of 22C and the number of carbon atoms of the part derived from a fatty acid is required to be in a 8-16C range. The ester compd. is obtd. by the esterification reaction in which the branch type alcohol of 22C and monobasic fatty acid of 8-16C are used. The compd. may be added into a magnetic paint or an ordinary lubricating agent may be further added into the compd.

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 an ester compound represented by the following general formula (1). A magnetic recording medium is provided.

(In the formula, R1 and R2 have 1 to 19 carbon atoms (However, R4
and R2 (the sum of carbon numbers is 20) is a straight chain or branched saturated alkyl group, and R3 is a straight chain or branched saturated alkyl group having 7 to 15 carbon atoms. ) [Function] The ester compound represented by the general formula (1) according to the present invention is very limited, and the portion derived from alcohol must be a branched alcohol having 22 carbon atoms. In addition, the number of carbon atoms in the part derived from fatty acids is 8 to 16.
It is necessary to be within the range of . It is not clear why the durability of magnetic recording media is greatly improved when such specific ester compounds are used as lubricants.

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 monobasic fatty acid having 8 to 16 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, 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 r-Fe.
Metal oxides such as 203, Fe, O,, Cry, and also Co-deposited 7-Fez03, Co-doped r -Fe, O
r-FetOx, 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. magnetic powder, Co, Fe-Co, Fe-
Examples include ultrafine powder of metals such as Ni or alloys. 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, polyacrylo doublet, nitrile rubber, epoxy resin, alkyd resin, polyamide, polyacrylic ester, polymethacrylic 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 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 r -FezO = 100 parts by weight PVC/acetic acid picopolymer cap 30 Nitrile butadiene rubber 15 Carbon black 7 Aluminum oxide 6 Toluene 150 Methyl ethyl ketone 150 Lecithin 1 part by weight Lubricant
6 Note) -1 Product name VAG manufactured by U, C, C, USA) *2
1432J (trade name, 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 manufactured by Nippon Polyurethane) was added.
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 lubricants used in Examples, 6 parts by weight of the various lubricants shown in Table 2 were used, and the other components and amounts were 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 Dewa ~ Kaoru Gakodani

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) is a straight chain or branched saturated alkyl group, and R_3 is a straight chain or branched saturated alkyl group having 7 to 15 carbon atoms. )