JPS62125529A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To provide the excellent lubricity to the titled medium by incorporating two kinds of ester compds. satisfying the general formula into a magnetic layer. CONSTITUTION:From 1-15wt% of the total amt. of the ester compd. satisfying general formula I and obtained by the esterification between Guerbet alcohol, etc., and a fatty acid, etc., and the ester compd. satisfying general formula II such as tridecyl stearate is incorporated into magnetic powder to form the magnetic layer. When this magnetic layer is used, the durability of the magnetic recording medium is not deteriorated, bleeding from the surface is eliminated, and excellent lubricity can be provided. In the formulas, R1 and R2 are 1-25C (where the total number of carbons in R1 and R2 is 22-34) straight-chain or branched-chain saturated or unsaturated alkyl groups, R3 is a 7-29C straight- chain or branched-chain saturated or unsaturated alkyl group, R4 is a 1-29C aliphatic hydrocarbonic group, and R5 is a 1-23C straight-chain or branched- chain aliphatic hydrocarbonic group or a 24-36C straight-chain aliphatic hydrocarbonic group (where the total number of carbons in R4 and R5 is 15-65).

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 drawbacks 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 on a non-magnetic support, in which the magnetic layer has the following general formula (I) υ (wherein R1 and R2 have a carbon number of 1 to 25 (wherein R1
and R2 have a total of 22 to 34 carbon atoms), and R3 is a linear or branched saturated or unsaturated alkyl group having 7 to 29 carbon atoms.

) and the following general formula (II) υ (wherein, R4 is an aliphatic hydrocarbon group having 1 to 29 carbon atoms, R
3 is a straight chain or branched aliphatic hydrocarbon group having 1 to 23 carbon atoms or a straight chain aliphatic hydrocarbon group having 24 to 36 carbon atoms (however, the sum of the carbon numbers of R4 and R6 is 15 to 65; The present invention provides a magnetic recording medium characterized by containing an ester compound represented by the following.

[Effect]

The magnetic recording medium of the present invention has the formula -a (I) in the magnetic layer.
) (hereinafter referred to as ester compound (I)
)) and an ester compound represented by the general formula (H) (hereinafter abbreviated as ester compound (r[)). When these specific ester compounds are used in combination, excellent lubricity is imparted, and as a result, the durability of the magnetic recording medium is greatly improved, but the reason why such excellent lubricity is imparted is not clear.

The ester compound (1) can be obtained, for example, by an esterification reaction between a branched alcohol and a fatty acid. This branched alcohol is called gel alcohol because of its synthesis method.

In the ester compound (n), R4 has 7 to 2 carbon atoms.
Preferred are aliphatic hydrocarbon groups in the range of 3. Further, R4 is preferably a straight chain or a branched group having a low molecular weight such as a methyl group or an ethyl group.

Specific compound names include tridecyl stearate, isotridecyl stearate, oleyl stearate, tridecyl palmitate, isotridecyl palmitate, cetyl myristate, isocetyl stearate, isostearyl palmitate, iso stearyl oleate,
Examples include eicosylmyristate.

Furthermore, the ester compound (1) and the ester compound (I
The total amount of I) used is usually 1 to 15% by weight based on the magnetic powder, and the amount of ester compound (1) and ester compound (
The usage ratio of If) is usually the weight ratio -? '(T) /
(II) It is in the range of -10/90 to 90/10.

The magnetic powder according to the present invention is needle-shaped fine r-Pe.
Metal oxides such as zO+, Fe30t, Cr0z,
Also, Co-coated T-FezO3, Co-doped 7-FezO
, γ-FezO, iron metal powder, barium ferrite in the form of microplates, and some of its Fe atoms are one of Ti, Co, , n, V, Nb, etc. Magnetic powder substituted with two or more types, Co, Fe-
Examples include ultrafine powder of metals or alloys such as Go and Fe-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.

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

Co-adhered r -Fez03 100 parts by weight PVC/vinyl acetate copolymer 0130 Polyurethane resin 1" 27 Polyurethane resin 2" 3 5 Carbon black 8 α-81□03
4 Toluene 67 Methyl ethyl ketone 67 Cyclohexanone 100 Note) sl Product name manufactured by Union Carbide Co., USA 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 five 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 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, lubricants of the type and amount shown in Table 2 were used, other components and their amounts were the same as in the example, and the method of the example was followed. A total of four 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 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. } and the following general formula (II) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼・・・・・・(II) {In the formula, R_4 is an aliphatic hydrocarbon having 1 to 29 carbon atoms basis,
R_5 is a linear or branched aliphatic hydrocarbon group having 1 to 23 carbon atoms, or a straight chain aliphatic hydrocarbon group having 24 to 36 carbon atoms (however, the sum of the carbon numbers of R_4 and R_5 is 15 to 23 carbon atoms).
65)} A magnetic recording medium characterized by containing an ester compound represented by the following. 2. The magnetic recording medium according to claim 1, wherein R_4 is an aliphatic hydrocarbon group having 7 to 23 carbon atoms.