JPS63164016A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the durability of a titled medium by incorporating tridecyl stearate having a branch, butyl stearate and butoxyethyl stearate into a magnetic layer. CONSTITUTION:The tridecyl stearate butyl stearate and butoxyethyl stearate expressed by the formula are added to the magnetic layer essentially consisting of magnetic powder (e.g.: Co-deposited gamma-Fe2O3) and resin binder (e.g.: polyurethane). In the formula, R denotes a branch alkyl of 13C. This lubricating agent system can be added into a magnetic coating compd. and the spraying thereof after dissolving the agent into a suitable solvent is also possible. Then, the medium such as floppy disk having the excellent durability is obtd.

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.

Various compounds have been proposed as lubricants.

They include various fatty acids, fatty acid esters, fatty acid amides,
Liquid paraffin, waxes, etc. However, it is extremely difficult to obtain satisfactory results in terms of performance, especially when these lubricants are used alone. Even if it is effective in improving durability, it often has poor compatibility with the resin binder and tends to bleed from the surface of the magnetic layer, or conversely, although it does not bleed, it is often insufficient in terms of improving durability.

Therefore, some of the above-mentioned compounds are sometimes used in combination for practical use, but at present it cannot be said that a fully satisfactory lubricant system has been obtained. In particular, recently, devices equipped with magnetic recording media such as floppy disks have been increasingly used outdoors, and magnetic recording media that are highly durable even under various environmental changes have been required along with the devices. .

[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 resin binder, in which the magnetic layer has the following formula (1) % formula % (11 (where R is carbon The present invention provides a magnetic recording medium characterized by containing an ester compound represented by (representing a branched alkyl group of number 13), (b) butyl stearate, and (C) butoxyethyl stearate.

The lubricant system according to the invention is composed of a very limited combination of ester compounds.

The ester compound represented by the formula (1) is tridecyl stearate, and it is necessary to use one having a branched alkyl chain derived from alcohol. Part of the tridecyl stearate may be partially substituted with unbranched tridecyl stearate, but the proportion of branched tridecyl stearate should be 60% by weight or more, more preferably 90% by weight or more.

In addition, the blending ratio of the ester compound (al, butyl stearate (b), and butoxyethyl stearate (C) represented by the above formula fl) is (81 parts by weight), assuming that the total is 100 parts by weight.
is 20 to 80 parts by weight, (bl is 10 to 40 parts by weight, fc
It is preferable that l is 20 to 80 parts by weight.

This lubricant system may be used by adding it to magnetic paint,
It may be dissolved in a suitable solvent and sprinkled onto the magnetic coating.

This lubricant system is usually used in an amount of 1 to 15% by weight based on the magnetic powder.

As the magnetic powder according to the present invention, fine needle-shaped r-F
etus, Fe=0. , CrOt, as well as Co-coated γ-F13zOs, Co-doped 7-F
γ-FelO, iron metal powder, platelet-shaped barium ferrite and its Fe
Magnetic powder, Co, Fe-Con, in which some of the atoms are substituted with one or more of Ti, Co, Zn+V, Nb, etc.
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 resin 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, boria-acrylic acid ester, polymethacrylic acid ester, polyvinyl acetate, polyvinyl butyral, vinylidene chloride, vinylidene chloride copolymer, nitrified cotton,
Examples include 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. Also,
Plasticizers and hardeners can also be added to adjust the hardness of the resin.

The amount of the resin binder is generally 15 to 60 parts by weight per 100 parts by weight of the magnetic powder. Even if the resin 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.

Example 1 The following mixture was kneaded in a sand mill for about 15 hours.

Thereafter, 7 parts by weight of a polyisocyanate compound (trimethylolpropane triisocyanate) was added to prepare a magnetic paint.

Next, this coating material was applied onto a polyethylene terephthalate film having a thickness of 75j111 so that the dry film thickness was 1.5-1, and after drying, calendering was performed. Furthermore,
This was left at 60° C. for 4 days to undergo a curing reaction, and then punched out into a disk shape, the surface polished and enclosed in a jacket to produce a floppy disk.

A durability test was conducted by loading this disk into a floppy disk accelerated durability test drive under the test conditions below. By measuring the running time until the playback output reached 70% of the initial value, Durability was evaluated.

The results are shown in Table 1.

<Test Conditions> ■ First, the temperature is 5°C and the humidity is 30χR,H for 8 hours.

■ Gradually increase the temperature and humidity until 40℃ and 8℃ after 4 hours.
0χR''.

■ Hold at 40℃, 80χR,H, for 8 hours.■ Gradually lower the temperature and humidity, and after 4 hours, hold at 5℃, 30χR,H.
, so that

■ Repeat this from now on.

Example 2 In Example 1, tridecyl stearate (branched with 9
5% by weight or more), 2.5 parts by weight of butyl stearate, and 2.7 parts by weight of butoxyethyl stearate.
A floppy disk was manufactured in the same manner as in Example 1 except for using parts by weight, and its durability test was conducted.

The results are shown in Table 1.

Example 3 A floppy disk was produced in the same manner as in Example 1 except that the vinyl chloride/vinyl acetate copolymer resin was 30 parts by weight and 15 parts by weight of nitrile butadiene rubber was used instead of the polyurethane resin. A durability test was conducted.

The results are shown in Table 1.

Comparative Examples 1 to 6 Floppy disks were manufactured in the same manner as in Example 1, except that the lubricant shown below was used instead of the lubricant consisting of tridecyl stearate, butyl stearate, and butoxyethyl stearate. Then, a durability test was conducted.

The results are shown in Table 1.

Lubricant Comparative Example 1... Oleyl oleate 8 parts by weight Comparative Example 2.
・Tridecyl stearate (branched at least 95% by weight)
8 parts by weight Comparative Example 3... Tridecyl stearate (branching is 95% by weight or more)/isocetyl stearate - 4 parts by weight/4 parts by weight Comparative Example 4... Tridecyl stearate (branching is 95% by weight or more) % or more) / Isocetyl stearate / Oleic acid = 3 parts by weight / 2 parts by weight / 3 parts by weight Comparative example 5... Butoxyethyl stearate 8 overlapping parts Comparative example 6... Butyl stearate / Butoxyethyl stearate Rate = 2.5 parts by weight 7 5.5 parts by weight Table 1

Claims (1)

[Claims] 1. A magnetic recording medium having a magnetic layer mainly composed of magnetic powder and a resin binder, the magnetic layer comprising (
a) Ester compound represented by the following formula (1) ▲Mathematical formula, chemical formula, table, etc.▼...(1) (In the formula, R represents a branched alkyl group having 13 carbon atoms.) A magnetic recording medium comprising (c) butyl stearate and (c) butoxyethyl stearate.