JPS6192429A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the running property of a magnetic recording medium by holding the ester of carboxymethylthio malic acid and alcohol of 8-22C to a magnetic recording medium. CONSTITUTION:There are monoester, diester and triester in the ester of the carboxymethylthio malic acid and alcohol and said ester may also be any of 3 kinds alone or the mixture composed thereof. The alcohol of 8-22C may be either satd. alcohol or unsatd. alcohol and the hydrocarbon group of the alcohol may be straight chain or have side chains. The amt. of the lubricating agent to be added is preferably 0.2-4pts.wt. PHR by 100pts.wt. magnetic powder in a magnetic layer if said agent is to be incorporated into the magnetic layer. Said amt. is preferably 0.2-20pts.wt. PHR by 100pts.wt. binder in a back coat layer if said agent is to be incorporated into the back coat layer on the rear of the base. The figure shows the magnetic recording medium formed with the magnetic layer 2 contg. the lubricant on the surface of the nonmagnetic base 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic recording medium having a magnetic layer on a non-magnetic support, such as a magnetic tape or a magnetic disk.

[Conventional technology]

Magnetic tapes are particularly required to have various characteristics, such as having a small coefficient of friction, smooth and stable running properties, a small amount of dust, and good splicability. That is, when a magnetic tape is used in a magnetic recording/reproducing device such as a VTR, it runs at high speed while physically contacting tape guides, magnetic belly button F, etc., so it has excellent wear resistance and can last for a long time. It is important to be able to drive stably. For example, Ig IF on the tape surface during recording or playback.
If the A coefficient changes, the tape will vibrate at the guide or magnetic head. As a result, the frequency of the signals recorded and played back on the tape (for example, timbre signals) changes, resulting in a sound different from the original frequency, or the tape vibration sound (so-called Q sound) can be heard directly. be.

In order to prevent this, various attempts have been made to impart lubricity to the tape. For example, a solid lubricant such as molybdenum disulfide, graphite, or wax is added to a magnetic paint containing magnetic powder and a binder. However, this solid lubricant is undesirable because it is not very effective for durability and, if added in large amounts, deteriorates the magnetic properties.

On the other hand, higher fatty acids, higher fatty acid esters, paraffinic hydrocarbons, silicone oils (e.g. dimethyl silicone oil, diphenyl silicone oil), etc. may be used as lubricants, but even these may provide sufficient durability and lubricity. Therefore, it is insufficient especially for the mains of a VTR. Moreover, blooming, which is a slippery ooze on the surface of the magnetic layer, is likely to occur, causing tape sticking phenomena, stick-slip, and the like.

[Problem that the invention seeks to solve]

The present invention has been made to correct the above-mentioned deficiencies, and an object of the present invention is to improve the running properties of a magnetic recording medium by using a novel lubricant as described above.

[Means for solving problems]

That is, the present invention provides a magnetic recording medium having a magnetic layer on a non-magnetic support, characterized in that the magnetic recording medium holds an ester of carboxymethylthiomalic acid and an alcohol having 8 to 22 carbon atoms. It relates to magnetic recording media.

Carboxymethylthiomalic acid has the following structural formula (% formula). Esters of carboxymethylthiomalic acid with alcohol include monoesters, diesters, and triesters, and these three types may be used alone or as a mixture thereof.

The alcohol having 8 to 22 carbon atoms may be either a saturated alcohol or an unsaturated alcohol, and the hydrocarbon group of the alcohol may be linear or may have a side chain.

When included in the magnetic layer, the amount of the /1Jif property used in the present invention is preferably 0.2 to 4 parts by weight (PHP) per 100 parts by weight of the magnetic powder in the magnetic layer. When it is included in the back coat layer (described later) on the back side of the base, it is preferably 0.2 to 20 parts by weight (PHR) per 100 parts by weight of the binder in Hack Coat Pi. Further, when a top coat layer or a coating layer (both described below) made of the above-mentioned lubricant is applied, the amount of the lubricant to be applied is preferably 1 to 1000 μ/M.

Furthermore, it is also possible to use the lubricant according to the invention in combination with other conventional lubricants mentioned above.

A magnetic recording medium, such as a magnetic tape, according to the present invention is illustrated in FIGS. 1 to 5.

FIG. 1 shows a magnetic layer (2) containing the lubricant of the present invention formed on the surface of a non-magnetic base (1). In the following figures, the layer containing the lubricant according to the invention is shown in large-scale cross-sections. FIG. 2 shows a state in which a top coat layer (3) made of a lubricant according to the present invention is formed on the surface of a magnetic layer (2). Figure 3 shows a coating layer (4) made of a lubricant according to the present invention on the back side of a non-magnetic base (1).
This shows the state in which a is formed. Figure 4 shows the non-magnetic base (1
Figure 5 shows a state in which the lubricant according to the present invention is contained in the back coat layer (5) formed on the back surface of the
This shows a state in which a coating layer (6) made of a lubricant according to the present invention is formed on Basokuko-1-J'5 (51).The back coat layer (5) is provided for various purposes,
This is for the purpose of stabilizing runnability by appropriately controlling the surface roughness of the bank surface, and for preventing static electricity. For this reason, the back coat layer may be coated with a mixture of carbon blank in a binder, or may further include a nonmagnetic pigment such as α-Fe203, alumina, talc, etc. The magnetic recording medium of the present invention can be applied not only to such magnetic tapes but also to magnetic disks having magnetic layers on the front or back surfaces. In addition, the lubricant according to the present invention is held at a position in the magnetic layer (2) or in the magnetic layer (2).
It can be variously placed on the front and/or back side of.

Magnetic powder that can be used in the magnetic layer of the present invention includes γFe2
O3, Fe3O4, T Mixed crystal of Fe2u3 and Fe50+, r Fe2 doped or coated with cobalt
0x or Fe3O4, CrO2, barium ferrite,
Various alloy powder magnetic materials (e.g. Fe-C0% Co-N
i, Fe-C.

-Ni, Fe-Co-B, Fe-Co-
Cr-B% Mn-Bi, Mn-11% Fe
Co V, etc.), iron nitride, etc., and two or more of these may be used in combination.

In addition, as a binder that can be used for the magnetic layer, vinyl chloride-
Vinyl acetate copolymer, vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl acetate-maleic acid copolymer, vinyl chloride-vinylidene chloride J (polymer, vinyl chloride-acrylonitrile copolymer, acrylic ester) -Acrylonitrile copolymer, acrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-styrene copolymer, thermoplastic polyurethane resin, phenoxy resin, polyvinyl fluoride, vinylidene chloride - Acrylonitrile copolymer, butadiene-acrylonitrile copolymer, acrylonitrile-butadiene-methacrylic acid copolymer, acrylonitrile-butadiene-acrylic acid copolymer, polyvinyl butyral, polyvinyl acecool,
Examples include cellulose derivatives, styrene-butadiene copolymers, polyester resins, phenol resins, epoxy resins, thermosetting polyurethane resins, urea resins, melamine resins, alkyd resins, urea formaldehyde resins, and the like.

When preparing the magnetic paint, use organic solvents such as ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohols such as methanol, ethanol, propatool, butanol, etc.
; Esters such as ethyl acetate, butyl acetate, ethyl lactate, glycol acetate, monoethyl ether; Glycol ethers such as ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, -dioxane; Aromatic hydrocarbons such as benzene, toluene, xylene, etc. ; aliphatic hydrocarbons such as hexane and heptane; nitropropane and the like can be used alone or as a mixture. Non-magnetic bases to which magnetic strips prepared with organic solvents are applied include polyesters such as polyethylene terephthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, polycarbonate, polyvinyl chloride, and polyamide. , polyimide, aluminum, metal materials such as copper, paper, and the like. Further, as a solvent for applying the top coat M consisting of a lubricant and the coating layer, a low boiling point solvent such as Freon, hexane, ethanol, etc. can be used.

Further, magnetic recording media to which the compound of the present invention is applied as a lubricant are not limited to so-called coated magnetic recording media in which the compound is coated with magnetic powder and a binder as described above to form a magnetic layer, but also metal ferromagnetic thin film type magnetic recording media. It is also used for magnetic recording media. This metal ferromagnetic thin film magnetic recording medium is formed by plating, vapor deposition, ion blasting, sputtering, or the like with a magnetic metal such as Co, Fe, Ni, or an alloy thereof on a nonmagnetic support. This metal ferromagnetic thin film magnetic recording medium has a high magnetic flux density because it does not require the use of a binder, and is useful for short wavelength, high density recording because it is formed into a very thin layer. .

〔Example〕

Although specific examples of the present invention will be described below, it goes without saying that the present invention is not limited to these examples.

Example 1 The above composition was used as a basic composition, 1.5 parts by weight of triester of carboxymethyl thiomalic acid and oleyl alcohol was added to the basic composition, mixed in a ball mill for 24 hours, and then taken out through a filter. Further, 4 parts by weight of a curing agent was added immediately before coating, and the mixture was stirred for 30 minutes. This magnetic material 1 was applied onto a polyethylene terephthalate film having a thickness of 12 μm so that the thickness after drying would be 5 μm, and after magnetic field orientation, it was dried and wound up. This was calendered and then cut into 1/2 inch width to prepare sample tapes.

Example 2 1.5% of the triester of carboxymethyl thiomalic acid and isostearyl alcohol was added to the basic composition of Example 1.
A sample tape was prepared in the same manner as in Example 1 using the magnetic paint containing 100% of the magnetic paint.

Example 3 A sample tape was prepared in the same manner as in Example 1 using a magnetic paint obtained by adding 1.5 parts by volume of triester of carboxymethylthiomalic acid and myristyl alcohol to the basic composition of Example 1.

Example 4 A sample tape was prepared in the same manner as in Example 1 using the basic composition of Example 1 as a magnetic paint. The magnetic layer of the sample tape was coated with 1.0% of triester of carboxymethyl thiomalic acid and oleyl alcohol. Owt%n
- The hexane solution is coated with a triester coating amount of 160 μ/
Example 5 A sample tape was prepared by coating (top coat) as shown in Example 5. A sample tape was prepared in the same manner as in Example 1 using the basic composition of Example 1 as a magnetic paint. In the magnetic layer of the sample tape, 1.0 wt% n-
A sample tape was prepared by applying (top coating) a hexane solution so that the coating amount of diester was 160 μ/M.

Example 6 Co was deposited on a 12 μm thick polyethylene terephthalate film by oblique vapor deposition to form a 1000-metal ferromagnetic thin film. On the surface of this metal ferromagnetic thin film, an O, byt% n-hexane solution of triester of carboxymethyl thiomalic acid and oleyl alcohol is applied (top coat) so that the coating amount of triester is 2μ/rrr. A sample tape was created.

Example 7 Co was deposited on a 12 μm thick polyethylene terephthalate film by oblique evaporation to form a 1000-metal ferromagnetic thin film. The surface of this metal ferromagnetic thin film was coated (top coated) with an O, 1wt% n-hexane solution of a diester of carboxymethyl thiomalic acid and oleyl alcohol at a coating weight of 2μ/M. I made a tape.

Comparative Example A sample tape was prepared in the same manner as in Example 1 using the basic composition of Example 1 as a magnetic paint.

The properties of the sample tapes prepared in the above Examples and Comparative Examples are shown in the following table.

In this table, ○ indicates good quality, and × indicates extremely poor quality.

Further, aging was carried out at 40° C. and 80% for 3 days.

〔Effect of the invention〕

As can be seen from the table, in the magnetic recording medium according to the present invention, the coefficient of friction can be suppressed to an extremely small value, and stick-slip can be avoided. In particular, according to the present invention, running deterioration due to aging, which has conventionally been a problem with magnetic recording media using the top coat method, can be resolved.

[Brief explanation of the drawing]

1 to 5 are cross-sectional views showing embodiments of magnetic recording media according to the present invention. (1) is the base, (2) is the magnetic layer, (3) is the top coat, (4) and (6) are the lubricant coating layers, and (5) is the hack coat layer.

Claims (1)

[Claims] 1. A magnetic recording medium having a magnetic layer on a non-magnetic support, characterized in that the magnetic recording medium holds an ester of carboxymethylthiomalic acid and an alcohol having 8 to 22 carbon atoms.