JPS62125530A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide the excellent lubricity to the titled medium and to improve the durability even under extensive service conditions by incorporating an ester compd. shown by the specified general formula and a fatty acid having the specified number of carbons into a magnetic layer. CONSTITUTION:From 1-15wt% of an ester compd. shown by general formula I and obtained by the esterification between Guerbet alcohol and a fatty acid and of a 8-30C fatty acid such as caprylic acid is incorporated into magnetic powder to form the magnetic layer. Excellent lubricity is provided to the magnetic recording medium using this magnetic layer, and the durability of the magnetic recording medium is improved even under extensive service conditions. In the formula, R1 and R2 are a 1-25C (where the total number of carbons in R1 and R2 is 22-34) straight-chain or branched-chain saturated or unsaturated alkyl group, and 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 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, 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 to obtain a magnetic recording medium that is imparted with good lubricity and has significantly improved durability even under a wide range of use environments.

I! Furthermore, the present invention provides a magnetic recording medium having a magnetic layer on a non-magnetic support, in which the magnetic layer has the following general formula (+
) υ (In the formula, R3 and R2 have 1 to 25 carbon atoms (however, R1
and R2 have a total of 22 to 34 carbon atoms), and R1 is a linear or branched saturated or unsaturated alkyl group having 7 to 29 carbon atoms.

) and a fatty acid having 8 to 30 carbon atoms.

[Effect]

The magnetic recording medium of the present invention includes the formula -i (I) in the magnetic layer.
) and a fatty acid having 8 to 30 carbon atoms.

When these are used in combination, excellent lubricity is imparted and the durability of the magnetic recording medium is improved, but the detailed reason for this is not clear.

The ester compound represented by the general formula (I) used in the present invention can be obtained, for example, by an esterification reaction between a branched alcohol and a fatty acid. This branched alcohol is called Guerbet alcohol because of its synthesis method.

Furthermore, among the fatty acids used in the present invention, fatty acids having a carbon number of 8 to
Those having 24 saturated, unsaturated, linear or branched chains are preferred. Examples of specific fatty acids include caprylic acid,
These include capric acid, lauric acid, myristic acid, balmitic acid, stearic acid, arachidic acid, behenic acid, 12-stearic acid, oleic acid, linoleic acid, erucic acid, and the like.

The total amount of the ester compound and fatty acid used is about 1 to 15% by weight based on the magnetic powder, and the ratio of the two used is usually ester compound/fatty acid = 9515 to 1.
0/90 (weight ratio), preferably ester compound/
Fatty acid = about 9515 to 50150.

The magnetic powder according to the present invention is fine needle-shaped r-Fe.
Metal oxides such as zO=, Pa1nt, Cr0z,
Also, Co-coated 7-Fe2O:+, Co-doped r-Fe4
r-Pez03 subjected to force U processing such as 03, 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-Co, F
Examples include ultrafine powder of metal or alloy such as e-Ni.

Among these, iron metal powder has particularly poor chemical stability, so to improve it, nickel, cobalt, titanium, silicon,
A small amount of aluminum or the like in the form of metal atoms, salts, or oxides may be added or the surface may be 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.

〔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 types and amounts of ester compounds and fatty acids shown in Table 1 as lubricants, mixtures having the compositions shown below were prepared.

Co-adhered r-Feze 3100 parts by weight PVC/vinyl acetate copolymer 30 Polyurethane resin 2 27 parts by weight Polyurethane resin 2 35 Carbon blank 8 α-A12034 Toluene 67 Methyl ethyl ketone 67 Cyclohexanone 100 Note) *1 Manufactured by Union Carbide, USA Product name V A
G H Book 2 Product name manufactured by Nippon Polyurethane Industries Co., Ltd. Book 3 Product name manufactured by Nippon Polyurethane Industries Co., Ltd. Next, the above mixture is kneaded in a sand mill for 5 hours, and then a lubricant is added and kneaded in a ball mill for 10 hours. Furthermore, a polyisocyanate compound (product name N32 manufactured by Sumitomo Bayer Urethane Co., Ltd.) was added to this.
A total of 6 types of magnetic paints were prepared by adding 5.4 parts by weight of 00). These paints were then applied onto a polyethylene terephthalate film with a thickness of 75 μm to a dry film thickness of 1.5 μm.
It was coated so as to have a thickness of μ, 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 determined 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. was determined.

The results are shown in Table 1.

Table 1 Comparative examples 1 to 4

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 22 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 the following and a fatty acid having 8 to 30 carbon atoms.