JPH02199624A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain such a medium with excellent durability and little abrasion of the magnetic layer by incorporating a specific ester compd. and a copolymer of vinyl chloride and a compd. having -COOH as a polar group into the magnetic layer. CONSTITUTION:The ester compd. expressed by formula I and the copolymer of vinyl chloride and the compd. having a polar group of -COOH or nitrocellulose having the same polar group are incorporated into the magnetic layer essentially comprising magnetic powder and a binder. In formula I, R represents an aliphatic hydrocarbon group with a branched chain with 3 - 10 carbon and R' represents a satd. or unsatd. aliphatic hydrocarbon group with 7 - 21 carbons. This gives more preferable lubricating property and the obtd. medium has significantly improved durability in a wide range of environments.

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.

[Prior Art and Problems to be Solved by the Invention] Magnetic recording media are generally produced by coating a substrate such as a polyester film with a magnetic paint consisting of magnetic powder, a binder, an organic solvent, and other necessary components. Floppy disks in particular come into contact with magnetic heads, jacket liners, etc. during recording and playback, so
Since the magnetic layer is easily abraded, a magnetic layer that is less abraded and has excellent durability is required.

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 to solve the problem]

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 containing magnetic powder and a binder as main components, in which the magnetic layer has (a) the following general formula (I) (wherein R has 3 to 10 carbon atoms). an ester compound represented by a branched aliphatic hydrocarbon group (R represents a saturated or unsaturated aliphatic hydrocarbon group having 7 to 21 carbon atoms); and (b) 10000 as a polar base. , -NR"3(R"
is a methyl group or an ethyl group), -503M (M is Na
or K), -OP(OH), and a copolymer of vinyl chloride, or a magnetic recording medium containing nitrocellulose having the same polar group as above. It provides:

The ester compound represented by the general formula (I) according to the present invention is very limited, and the part derived from alcohol is a branched alcohol having 3 to 10 carbon atoms, and the part derived from fatty acid is a branched alcohol having 3 to 10 carbon atoms. is a monobasic fatty acid having 8 to 22 carbon atoms, preferably a monobasic fatty acid having 12 to 18 carbon atoms.

Examples of branched alcohols having 3 to 10 carbon atoms include isopropyl alcohol, isobutyl alcohol, secondary butyl alcohol, tertiary butyl alcohol, isopentyl alcohol, secondary pentyl alcohol, tertiary pentyl alcohol, 3-pentyl alcohol, and 2-methyl. -1-butanol, 3-methyl-2-butanol, secondary hexyl alcohol, 3-hexyl alcohol, 2-hebutyl alcohol,
3-heptyl alcohol, 4-heptyl alcohol, tert-heptyl alcohol, 2-ethylhexyl alcohol, 2-octatool, 3-octatool, 4-
octatool, 2-decanol, 3-decanol, 4-
Examples include decanol and 5-decanol. Particularly preferred are isopropyl alcohol, isobutyl alcohol, secondary butyl alcohol, and 2-ethylhexyl alcohol.

Examples of the monobasic fatty acid having 8 to 22 carbon atoms include palmitic acid, stearic acid, myristic acid, and oleic acid.

The ester compound represented by the above general formula (I) according to the present invention includes a branched alcohol having 3 to 10 carbon atoms as described above,
It can be obtained by an esterification reaction using a monobasic fatty acid having 8 to 22 carbon atoms.

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. The amount of the ester compound of the present invention added is preferably 0.1 to 10 parts by weight, more preferably 0.5 to 7 parts by weight, per 100 parts by weight of the magnetic powder. Furthermore, a conventional lubricant may be added to the ester compound of the present invention.

In the present invention, -COQI (.

NR'3 (R" is a methyl group or an ethyl group), -S0
A copolymer of vinyl chloride and a compound having at least one polar group selected from 3M (M is Na or K), OP (Oll) t, or nitrocellulose having the same polar group as above is used. In particular, a vinyl chloride copolymer having a carboxylic acid as a polar group is preferred.

Examples of the compound having the above polar group include maleic acid and various commercially available (meth)acrylic compounds having the above polar group.

In the present invention, in addition to the above-mentioned vinyl chloride copolymer or nitrocellulose having a polar group, binders conventionally used, such as polyurethane, polyester, polyvinyl chloride, vinyl chloride/vinyl acetate copolymer, polyacrylonitrile, nitrile, etc. Rubber, epoxy resin, alkyd resin, polyamide, polyacrylic ester, polymethacrylic 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 can also be used. Furthermore, a plasticizer or a hardening agent may be added to adjust the hardness of the resin.

In the present invention, the blending amount of the binder is generally 1 part of the magnetic powder.
The amount is 15 to 60 parts by weight per 00 parts by weight. 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. In addition, the content of the vinyl chloride copolymer or nitrocellulose having the above polar group in the binder is 40% by weight.
The above is preferable, and when used in combination with other binders, it is preferable to use polyurethane resin.

The magnetic powder used in the present invention is fine needle-shaped T.
Metal oxides such as FezO, Fe30a, Crow, and Co-coated 7-Fe, 0. , Co-doped γ-
Fe, 0. γ-Fe, 0. ,
Iron metal powder, platelet barium ferrite and its F
Magnetic powder, Co, Fe in which a part of e atoms are substituted with one or more of Ti+ Co, Zn+ V+ Nb, etc.
Examples include ultrafine powder of metal or alloy such as Co+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.

In addition to the above-mentioned components, additives such as abrasives and antistatic agents commonly used in this field can be added to the magnetic layer of the magnetic recording medium of the present invention.

〔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 and Comparative Examples 1 to 3 Co -7-Fears too
Part by weight Vinyl chloride copolymer or nitrocellulose (Table 1) 13 Im polyurethane resin 1113 α-^1x (h 5 Carbon black 5 Polyisocyanate compound*z3 Methyl ethyl ketone 100 Toluene
100 cyclohexanone
100 Note) Umbrella 1 Product name manufactured by Nippon Polyurethane Co., Ltd. N-2304 A magnetic coating film was created by applying and drying the paint on a polyester base film.

After slitting this into a width of 172 inches, it was loaded into a recording/reproducing device and set in a still state under 20''C 165% RH, and durability was evaluated based on the time until the initial output decreased by 3 dB.

The results are shown in Table 1.

Claims (1)

[Claims] 1. In a magnetic recording medium having a magnetic layer mainly composed of magnetic powder and a binder, the magnetic layer has (a) the following general formula (I) ▲ Numerical formula, chemical formula, table, etc. ▼ ...(I) (wherein R represents a branched aliphatic hydrocarbon group having 3 to 10 carbon atoms, and R' represents a saturated or unsaturated aliphatic hydrocarbon group having 7 to 21 carbon atoms. (b) Polar groups include -COOH, -NR''_3 (R'' is methyl or ethyl group), -SO_3M (M is Na or K), ▲Mathematical formulas, chemical formulas, tables, etc.▼ A magnetic recording medium comprising a copolymer of vinyl chloride and at least one compound selected from the above, or nitrocellulose having the same polar group as described above.