JPS6076019A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the travelling of a titled magnetic medium by using a compd. contg. an epoxy group as a lubricant. CONSTITUTION:The magnetic recording medium contains a compd. shown by formula (1) or (2) where R and R' are alkyl groups contg. either a straight chain or a side chain, and the carbon numbers of R and R' are preferably regulated respectively to 8-30 and to 7-29. 0.2-4pts.wt. (PHP) said compd. is preferably added to 100pts.wt. magnetic powder when the compd. is incorporated into a magnetic layer, and 0.2-20pts.wt. (PHR) is desirably added to 100pts.wt. binder in said layer when the compd. is incorporated into a back coat layer. In addition, the amt. of a lubricant to be coated is desirably regulated to 1-1,000mg/ m<2>.

Description

DETAILED DESCRIPTION OF THE INVENTION 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.

Magnetic tapes are particularly required to have various properties, including a low coefficient of friction, smooth and stable running properties, a small amount of powder falling off, and good splicability. That is, when magnetic tape is used in magnetic recording and reproducing devices such as VTRs, it runs at high speed while physically contacting tape guides, magnetic heads, etc., so it has excellent wear resistance and remains stable over long periods of time. It is important to be able to drive in For example, if the friction coefficient of the tape surface changes during recording or reproduction, the tape will vibrate at the guide or magnetic head. As a result, the signals recorded and played back on the tape (for example, audio signals) change in frequency, resulting in a sound different from the original frequency, or the vibration of the tape (so-called Q
The disadvantage is that the sound (sound) can be heard directly.

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 in improving durability and, when 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. are sometimes used as lubricants, but these also provide sufficient durability and lhability. This is particularly insufficient for use as a VTR centerpiece.Furthermore, blooming in which the lubricant oozes onto the surface of the magnetic layer is likely to occur, causing tape sticking phenomena, stain slips, and the like.

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

That is, the present invention relates to a magnetic recording medium having a magnetic layer on a non-magnetic support, characterized in that the magnetic recording medium contains the compound shown below.

In the chemical formula (where R and R' represent an alkyl group), R may be either a straight chain or an alkyl group having a side chain, and R preferably has 8 to 30 carbon atoms. If the carbon number of R is 7 or less, the lubricating effect will be insufficient, and if it is 31 or more, synthesis will be difficult. In particular, it is more desirable that R has 12 to 18 carbon atoms.

The other compound according to the present invention may be either a linear alkyl group or an alkyl group having a side chain, and R' preferably has 7 to 29 carbon atoms. R'
If the number of carbon atoms in is 6 or less, the lubricating effect will be insufficient;
If it is 0 or more, synthesis becomes difficult. In particular, the number of carbon atoms in R' is 11
It is more desirable that it is 17.

R OC112CIl CH2 used in the present invention
When it is included in the magnetic layer, it is preferably 0.2 to 4 parts by weight (PHP) per 100 parts by weight of the magnetic powder in the magnetic layer. In addition, when it is included in the bank coat layer (1 & above) on the back of the base, the binder 100 in the bank coat layer (1 & 7)
It is desirable that the amount is 0.2 to 20 parts by weight (PHR). Furthermore, when forming a top coat layer or a coating layer (both described below) made of the above-mentioned lubricant, the amount of the lubricant applied is 1 to 1000 mg/rd.
It is desirable that

Next, a method for synthesizing a lubricant according to the present invention will be explained. .

1) An addition reaction between a higher alcohol or fatty acid and excess epichlorohydrin is carried out under reflux using a Lewis acid (higher alcohol) or a tertiary amine (fatty acid) as a catalyst.

Lewis Catalyst (Ill 2) After the excess epichlorohydrin is evaporated and recovered, a slightly excess equivalent amount of sodium hydroxide is added to carry out a ring-closing reaction.

(A) ROC+(2CHCH2Cl + Na011
(Ill 3) The precipitated sodium chloride water is removed by filtration to obtain a lubricant according to the present invention.

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 top coat Jiif + made of a lubricant according to the present invention on the surface of the magnetic layer (2).
3) is formed. Figure 3 is.

A state in which a coating layer (4) made of a lubricant according to the present invention is formed on the back surface of a non-magnetic base (1) is shown. FIG. 4 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 non-magnetic base (11), and further, FIG. This shows a state in which a coating layer (6) made of a lubricant according to the present invention has been formed.The bank coat layer (5) is provided for various purposes, but it is possible to control the surface roughness of the bank surface to make it easier to run. The purpose is to stabilize the properties and prevent static electricity.For this reason, the back coat layer is coated with a mixture of carbon blank in a binder, and a non-magnetic pigment such as α-Fe20a-
, alumina, talc, etc. may be mixed. 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 position where the lubricant according to the present invention is held is located in the magnetic layer (2).
It can be placed inside, or on the front and/or back side of the magnetic layer (2).

As the magnetic powder that can be used in the magnetic layer of the present invention, γ-Fe
2O3, Fe504, r Mixed crystal of Fe2O3 and Fe50+, γ-Pe20 doped or coated with cobalt
3 or Fe504, CrO2, barium ferrite,
Various alloy powder magnetic materials (e.g. Fe-Co, Go
-Ni, Fe-G.

-Ni,,Fe-Co-B,Fe-Co-
Cr-B XMn -Bis Mn-^LFe-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 copolymer,
Vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, acrylic ester-vinylidene chloride copolymer, methacrylic 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 Polymer: Acrylonitrile-butadiene-acrylic acid copolymer, polyvinyl butyral, polyvinyl butyral, cellulose derivative, styrene-butadiene copolymer, polyester resin, phenol resin, epoxy resin, thermosetting polyurethane resin, urea resin, melamine resin, Examples include alkyd resins and urea formaldehyde resins.

When preparing magnetic paint, organic solvents such as ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; methanol, ethanol,
Alcohol such as propatool, butanol; ethyl acetate, butyl acetate, lactic acid: 1) Lt, glycol acetate,
Esters such as monoethyl ether; glycol ethers such as ethylene glycol dimethyl ether, ethylene glycol monoethyl ether, and dioxane; aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as hexane and heptane; nitropropane, etc. can be used alone or as a mixture. Non-magnetic bases for applying magnetic paint prepared with this organic solvent include polyesters such as polyethylene terephthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, polycarbonate, polyvinyl chloride, polyamide, Metal materials such as polyimide, aluminum, copper, etc.
Examples include paper. Further, as a solvent for applying the top coat layer and the coating layer consisting of a lubricant, a weakly polar and low boiling point solvent such as Freon, hexane, and ethanol 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 coating-type magnetic recording media in which a magnetic layer is formed by coating together with magnetic powder and a binder as described above, but also metal thin film magnetic recording media. It also applies to recording media. This metal thin film type magnetic recording medium is one in which a magnetic metal such as Co, Fe, Ni, or an alloy thereof is formed on a nonmagnetic support by plating, vapor deposition, ion blasting, sputtering, or the like. This metal thin film magnetic recording medium has a high magnetic flux density because it does not require the use of a binder, and because it is formed into an extremely thin layer, it
Useful for high-density recording.

The present invention will be explained below with reference to Examples.

Example 1 Co deposition r Fe20a 100 parts by weight Carbon (antistatic agent) 5 Lecithin (dispersant) 1 \ 1 Methyl ethyl ketone 150 parts by weight Methyl isobutyl ketone 150 The above composition was mixed in a ball mill for 24 hours. The mixture was taken out through a filter, and immediately before coating, 1 part by weight of a curing agent was added and stirred for 30 minutes. This magnetic paint was applied onto a polyethylene terephthalate base 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 rolled up. This was calendered and then cut to a width of 1.5 inches to prepare a sample tape.

Example 2゜Example 1. Myristyl glycidyl ether lauryl glycidyl ether of Example 1. Using a magnetic paint with the same composition as in Example 1,
A sample tape was created in the same manner as in Example 3.

Example 1. Glycidyl ester of myristyl glycidyl ether lauric acid Example 1 was prepared using a magnetic paint having the same composition as in Example 1.

A sample tape was prepared in the same manner as above.

Example 4.

Example 1. Myristyl glycidyl ether○ Glycidyl ester of myristic acid Example 1. Example 1 using a magnetic paint having the same composition as in Example 1.

A sample tape was prepared in the same manner as above.

Comparative example 1.

Co adhesion r Fe203, 100 parts by weight Carbon (antistatic agent) 5 Lecithin (dispersant) 1 Methyl ethyl ketone 150 Methyl isobutyl ketone 150 Using the above composition, Example 1. A sample tape was prepared in the same manner as above.

Example 5.

Comparative example 1. A sample tape was prepared by applying (top coat) a myristyl glycidyl ether phosphorus n-hexane solution to the magnetic layer of the sample tape prepared in step 1 so that the coating amount of myristyl glycidyl ether was 80 mg/rrr.

Example 6.

Comparative example 1. A sample tape was prepared by applying (top coating) a lauryl glycidyl ether U n-hexane solution to the magnetic layer of the sample tape prepared in step 1 in such a manner that the coating amount of lauryl glycidyl ether was 8 On+g/rrr.

Example 7゜Comparative Example 1. A sample tape was obtained by applying (top coat) a solution of glycidyl ester of lauric acid in n-hexane to the magnetic layer of the sample tape prepared in the above so that the amount of glycidyl ester of lauric acid applied was 80 mg/rrl.

Example 8 Comparative Example 1. A sample tape was prepared by applying (top coating) a glycidyl ester of myristic acid n-hexane solution to the magnetic layer of the sample tape prepared in step 1 so that the coating amount of glycidyl ester of myristic acid was 80a+g/nf.

Example 9 Comparative Example 1. A solution of glycidyl ester of isostearic acid in n-hexane was applied to the magnetic layer of the sample tape prepared in 1.
A sample tape was prepared by coating (top coat) so that the concentration was mg/rrf.

Comparative Example 2 A magnetic layer was formed by vacuum evaporating Go to a thickness of 1000 mm using an oblique evaporation method on a base made of polyethylene terephthalate with a thickness of 12 μm, and the sample tape was cut to a predetermined width. .

Example 10° Comparative Example 2. A sample tape was prepared by applying (top coat) a myristyl glycidyl ether n-hexane solution to the magnetic layer of the sample tape prepared in step 1 in such a manner that the coating amount of myristyl glycidyl ether was 20 mg/trr.

Example 11゜Comparative Example 2. A sample tape was prepared by applying (top coat) a solution of glycidyl ester of myristic acid in n-hexane to the magnetic layer of the sample tape prepared in step 1 so that the coating amount of glycidyl ester of myristic acid was 20 mg/cd.

In this table, ◎ indicates extremely good, Q indicates good, △ indicates poor, and × indicates extremely poor.

Further, aging was performed at a temperature of 60° C. for 3 days.

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 oral deformation, which has been a problem in the past with magnetic recording media using the top coat method, can be solved.

[Brief explanation of drawings]

1 to 5 are cross-sectional views showing embodiments of magnetic recording media according to the present invention. (11 is the base, (2) is the magnetic layer, (3) is the top coat, +41 (6) is the lubricant coating layer, and (5) is the back coat layer.

Claims (1)

[Scope of Claims] A magnetic recording medium having a magnetic layer on a non-magnetic support, characterized in that the magnetic recording medium has a chemical formula 5 (wherein R, R' represents an alkyl group.)