JPS61214216A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having improved lubricity and durability by incorporating a prescribed alkenyl succinic acid deriv. into a magnetic layer consisting essentially of magnetic powder and binder. CONSTITUTION:1 or 2 kinds of the alkenyl succinic acid deriv. selected from the group consisting of the compd. expressed by general formulas I, II are incorporated into the magnetic layer consisting essentially of the magnetic powder and binder. In formulas, R1 denotes an alkenyl group of 6-30C, R2 denotes an alkyl group or alkenyl group of 1-18C and M denotes any among a hydrogen group, alkali metal, ammonium ion or alkanol ammonium salt. These alkenyl succinic acid deriv. may be added into a magnetic paint or may be coated on the magnetic layer after dissolving the same into a suitable solvent. The deriv. is used at 1-15wt% by the weight of the magnetic powder.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to magnetic recording media. More specifically, the present invention relates to a magnetic recording medium with improved durability, which is obtained by coating a base film with a magnetic paint containing magnetic powder and a binder as main components.

[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.

As this lubricant, fatty acids, fatty acid esters, liquid paraffin, etc. are used. However, conventionally used lubricants have not had satisfactory lubricity. For example, it has been widely used as a lubricant for magnetic recording media,
The fatty acid esters used include oleyl oleate, butoxyethyl stearate, butyl stearate,
There are isocetyl stearate, etc., but these improve the durability of the medium, but are not sufficient, and when using fatty acids such as stearic acid and oleic acid, or hydrocarbon-based lubricants such as liquid paraffin. Although it is effective in improving durability, it has poor compatibility with the binder, so if used in a large amount, it tends to bleed from the surface of the magnetic layer, which limits the amount added.

[Means for solving problems]

The present inventors have found that good lubricity is imparted to the magnetic layer, durability is greatly improved, the lubricant does not bleed onto the surface of the magnetic layer, and it can be used in a wide range of environments from high to low temperatures. However, as a result of intensive research to obtain a magnetic recording medium that does not deteriorate in durability, the present invention has been achieved.

That is, the present invention provides a magnetic recording medium having a magnetic layer mainly composed of magnetic powder and a binder, wherein the magnetic layer is selected from the group consisting of compounds represented by the following general formulas (1) and (2). The present invention provides a magnetic recording medium characterized by containing one or more alkenylsuccinic acid derivatives.

(In the formula, R3 is an alkenyl group having 6 to 30 carbon atoms, R2 is an alkyl group or alkenyl group having 1 to 18 carbon atoms, and gate represents either a hydrogen atom, an alkali metal, an ammonium ion, or an alkanol ammonium ion) In the formula, R7, R2 and H represent the same meanings as above) [
Effect] The compound represented by the general formula (1) according to the present invention is
It is an alcohol ester of alkenylsuccinic acid or a salt thereof, and the compound represented by general formula (2) is an amide of alkenylsuccinic acid or a salt thereof.

In these compounds, the alkenyl group represented by R8 has 6 to 30 carbon atoms, and preferably has 12 to 18 carbon atoms. Further, the alkyl group or alkenyl group represented by R2 directly bonded to the ester group or amide group has 1 to 18 carbon atoms, but especially 3 to 18 carbon atoms.
8 branched ones are preferred.

These alkenylsuccinic acid derivatives may be added to the magnetic paint, or may be dissolved in a suitable solvent and applied onto the magnetic layer by a method such as spraying.

As the magnetic powder according to the present invention, fine needle-shaped r-F
Metal oxides such as ezO,, Fe50*, Cr(lz), as well as Co-coated 7-Fe2O3, CO-doped T-
γ-FezO+ processed like Fe, 03,
Iron metal powder, platelet barium ferrite and its F
Magnetic powder in which a part of e atoms are substituted with one or more of Ti, Co, Zn, V, Nb, etc., Co, Fe-Co,
Examples include ultrafine powder of metal or alloy such as 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, glass, etc. Examples include wire, 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 alkenylsuccinic acid derivative selected from the compounds represented by the above general formula (1) or (2) 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 12 Using the lubricants shown in Table 1, mixtures having the compositions shown below were prepared.

Co adhesion r -FezO+ I O0 parts by weight Lecithin 1 PVC/acetic acid picopolymer 30 Nitrile butadiene rubber 0 15 Carbon black 7 Aluminum oxide 6 Toluene 1.50 Methyl ethyl ketone 150 Lubricant 6 Note) *1 US U, C, C, Product name: VAGH book 2
1432J (trade name, manufactured by Nippon Zeon Co., Ltd.) Next, the above mixture was mixed and dispersed in a sand mill for 15 hours, and then 7 parts by weight of Coronate L (manufactured by Nippon Polyurethane ■), a polyisocyanate compound, was added thereto to prepare a magnetic paint.

Next, this was applied onto a 75 micron thick polyethylene terephthalate film so that the dry film thickness was 1.5 microns, and after drying, it was calendered.

Furthermore, after being left to cure for 4 days at a temperature of 60° C., it was punched out into a disk shape and the surface was polished to produce a magnetic disk.

Next, press these discs and apply more pressure than usual (
The durability of each sample was determined by loading the sample into a floppy disk accelerated durability test drive, and measuring the running time until the playback output reached 70% of the initial output at 5° C. using the same drive.

The results are shown in Table 1.

Table 1 Comparative Examples 1 to 4 Magnetic paints and magnetic disks were manufactured according to the method of Examples using 6 parts by weight of the lubricants shown in Table 2 instead of the lubricants used in Examples. A durability test was conducted on these disks in the same manner as in the examples.

The results are shown in Table 2.

Table 2

Claims (1)

[Claims] 1. A magnetic recording medium having a magnetic layer mainly composed of magnetic powder and a binder, wherein the magnetic layer is made of a compound selected from the group consisting of compounds represented by the following general formulas (1) and (2). A magnetic recording medium characterized by containing one or more selected alkenylsuccinic acid derivatives. ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(1) (In the formula, R_1 is an alkenyl group having 6 to 30 carbon atoms, R_
2 is an alkyl group or alkenyl group having 1 to 18 carbon atoms, M
represents either a hydrogen atom, an alkali metal, an ammonium ion or an alkanol ammonium ion) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(2) (In the formula, R_1, R_2 and M have the same meanings as above. represent)