JPH0487022A - Magnetic coating material and magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain excellent lubricity without impairing the durability of a magnetic layer and without generating blooming by incorporating the aliphat. acid ester obtd. from straight chain fatty acid and hydrogenerated cyclohexyl normal propanol into the above coating material. CONSTITUTION:The aliphat. acid ester obtd. from straight chain fatty acid and hydrogenated cyclohexyl normal propanol is used. The straight chain fatty acid refers to so-called fatty acid and can be expressed by n-CNH2N+1COOH, where N=9 to 17, i.e. 10 to 18C are preferable as the fatty acid. The hydrogenated cyclohexyl normal propanol is expressed by formula I. The fatty acid ester is used preferably at 1.5 to 6.0pts.wt., more preferably 2.0 to 4.0pts.wt. per 100pts.wt. magnetic powder. The magnetic recording medium having the excellent lubricity, good durability and good traveling stability is formed in this way.

Description

[Detailed Description of the Invention] [Field of Industrial Application] Does the present invention impart lubricity to the magnetic layer? This invention relates to a magnetic paint with improved lubricant and a magnetic recording medium using the same.

BACKGROUND OF THE INVENTION Magnetic recording media such as magnetic tapes and magnetic disks are widely used in the video field, audio field, computer field, and the like. Coating-type magnetic recording media, in which a magnetic coating consisting of magnetic powder, resin, solvent, dispersant, and other additives is applied to a support and dried to form a magnetic coating, are also used as such magnetic recording media. ing.

In recent years, magnetic recording media have been required to have higher recording densities as well as higher reliability. For this reason, a magnetic layer is formed by making fine particles of shikimagnetic powder and filling them with high density. In addition, attempts have been made to make the magnetic layer thinner, and to improve the running properties of the magnetic layer.

In particular, for example, a magnetic tape is repeatedly recorded and re-addressed by being rubbed by a magnetic head, a guide roller, a rotating cylinder, etc. while it is running. Furthermore, in the case of a videotape, a still image is sometimes viewed during playback, and in this case, the same location of the magnetic layer is repeatedly rubbed by a magnetic head. Therefore, magnetic tapes are required to have no damage to the magnetic layer even when used for long periods of time in these cases, but in order to achieve this and improve recording and playback, it is necessary to improve the lubricity and durability of the magnetic layer. It is also required to have good running stability. Specifically, it is required to reduce the coefficient of friction, improve wear resistance, and prevent magnetic powder from falling off.

[Problem to be solved by the invention]

A conventional method for improving the lubricity of the magnetic layer is to add a solid lubricant such as molybdenum disulfide, wax, or graphite to the magnetic paint.

However, although the magnetic layer to which these solid lubricants are added has an effect on lubricity, it may impair the durability of the magnetic layer.

On the other hand, higher fatty acids, normal higher fatty acid esters obtained using normal aliphatic alcohols, paraffinic hydrocarbons, silicone oils (e.g. dimethyl silicone oil, diphenyl silicone oil), etc. are also used as lubricants. However, magnetic layers using these materials not only do not exhibit sufficient lubricity and durability, but also suffer from the so-called blooming phenomenon in which these lubricants seep onto the surface of the magnetic layer. When this blooming occurs, problems arise in that the magnetic layer sticks to the rotating cylinder or the like with which it comes in contact, a so-called sticking phenomenon, and that the surface of the rotating cylinder gets dirty and this dirt accumulates, impairing its function.

An object of the present invention is to provide a magnetic recording medium that does not deteriorate the durability of the magnetic layer, does not cause the blooming phenomenon, and has excellent lubricity, and a magnetic coating therefor.

[Means to solve the problem]

In order to solve the above problems, the present invention is characterized in that a magnetic paint for forming a magnetic layer on a support contains a fatty acid ester obtained from a linear fatty acid and hydrogenated cyclohexino 1-normal propatool. We propose a magnetic paint that does this.

At this time, the number of carbon atoms of the straight chain fatty acid is larger than IO and smaller than 18, and the fatty acid ester is 1.5 to 1.5 to
It is also preferable that the content is 6.0% by weight.

The present invention also provides a magnetic recording medium using the above coating material.

Next, the present invention will be explained in detail.

In the present invention, a fatty acid ester consisting of a straight chain fatty acid and hydrogenated cyclohexyl normal propanol is used. The straight chain fatty acid is a so-called normal fatty acid and can be expressed as n-CHH-COOH, where N=9
~17, that is, preferably 10 to 8 carbon atoms as a fatty acid. In addition, hydrogenated cyclohexyl normal propanol may not improve the durability such as the powder fall prevention effect of the magnetic layer or the durability of steel, and the same may occur if the hydrogenated cyclohexyl normal propanol is too large. There is a tendency to In addition, if the N is too small or too large, the effect of improving the dynamic friction coefficient of the magnetic layer may be small.
=9 to 17 are preferred.

The above fatty acid ester is 71 parts per 100 parts of magnetic powder.
．． 5-6. The Oi amount s is preferably 2.0 to 4.0 parts by weight; if it is too small, the beak effect of the magnetic layer will be small (and if it is too large, blooming etc. may occur).

Examples of the binder resin used in the magnetic recording medium of the present invention include vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate copolymer-vinyl 7/L/D-B
v Copolymer, vinyl chloride-vinylacetate-maleic acid copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, acrylic ester-vinylidene chloride copolymer Polymer, methacrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-styrene copolymer, thermoplastic polyurethane resin, polyfluorinated vinyl, vinylidene chloride-acrylonitrile copolymer, butadiene-acrylonitrile copolymer, acrylonitrile-
butadiene-methacrylic acid copolymer, polyamide resin,
Examples include resins such as polyvinyl butyral, cellulose derivatives, styrene-butadiene copolymers, polyester resins, and synthetic rubbers such as polybutadiene.

Thermosetting resins are also used, such as phenolic resins, epoxy resins, thermosetting polyurethane resins, urea resins, melamine resins, 'fulkyd resins, urea-formaldehyde resins, silicone resins, acrylic reaction resins, and epoxy-polyamide resins. , nitrocellulose-melamine resins, mixtures of high molecular weight polyester resins and isocyanate prepolymers, mixtures of polyester polyols and polyisocyanates, urea formaldehyde resins, mixtures of low molecular weight glycols/high molecular weight diols/triphenylmethane triisocyanates, polyamine resins and Examples include mixtures of these, and among these, it is preferable to use a combination of those that have good dispersibility in the ferromagnetic powder.

In addition, as magnetic powder, TFe203, r-Fez03
and Fe3O4 crystals, CrO2, and cobalt-coated r-
Examples include Fe203 and Fe z O4. Further, nasal oxide magnetic powders such as metal magnetic powders, metal nitride magnetic powders, and metal carbide magnetic powders can also be used, and both can also be used in combination.

In addition to the above-mentioned binder resin and magnetic powder, the magnetic paint also contains an organic solvent, and if necessary, the magnetic paint also contains a dispersant, an abrasive, a filler, an antistatic agent, a rust preventive, and a fungicide. , etc. are selectively mixed. A known method is used as the manufacturing method.

This magnetic paint is applied to a support such as a polyethylene terephthalate film (PET film) using a known coating method such as a doctor blade, reverse roll, gravure roll, or spinner coat. Depending on the application, the magnetic powder is oriented and dried. A magnetic recording medium is obtained by performing smoothing treatment.

[Effect]

When the above-mentioned higher fatty acid ester is contained in the magnetic layer, i! ! [It is thought that they are compatible with each other and float moderately on the surface of the magnetic layer, but the details are not clear.

〔Example〕

Next, the present invention will be explained in detail.

Example I Co-containing r-Fe2O2 100M 9 parts (average particle size 0.2 μrn Hc=8506e) A
1203 (average grain i0.2 μm) 5
Part by weight Vinyl chloride Vinyl acetate copolymer 11 parts by weight Polyurethane resin 11 parts by weight n-C1
Fatty acid ester consisting of 5H51COOH and <E>CH2CH2CH20H 3 parts by weight Carbon black 5 parts by weight (manufactured by CABOFT Va
lcan 72) Methyl ethyl ketone 1
30 parts by weight toluene 130
Parts by weight or more of the mixture were mixed in a sand mill for 5 hours, and 3 parts by weight of a curing agent (isocyanate compound) was added to the resulting dispersion to obtain a magnetic paint.

This ifH'! The paint is applied onto a 14 μm thick PET film (polyethylene terephthalate film) using a gravure roll so that the film thickness after drying is 4 to 6 μm, and dried.

Thereafter, the magnetic layer was subjected to a calender treatment to give a mirror finish, and slits were made into 1/2 inch widths, and the slits were kept at 50° C. for sufficient hardening.

Using the sample magnetic tape obtained in this way, dynamic friction coefficient, powder drop, running test on VTR equipment, and steel durability test were carried out.1. The results are shown in Table 1. In addition, the saturation magnetic flux density (as (G)) of the magnetic layer and the squareness ratio Br
Table 1 shows the results of measuring /Bs using a sample vibrating magnetometer (manufactured by Riken Denshi Co., Ltd.).

To measure the coefficient of dynamic friction, one end of a magnetic tape wound on a reel is pulled out, wrapped around a cylinder parallel to the reel axis and separated from the reel for about half a turn, then folded back and taken up on a powered take-up reel. A tape tension detector on the drawer side is installed between the drawer reel and the cylinder, and the magnetic tape is moved at a speed of 3.3 ell/sec. When the magnetic tape starts to move and the tape tension on the pull-out side and the tape tension on the take-up side each show stable values, the former is defined as T1, the latter as T2, and the contact angle at which the tape is wound around a cylinder is expressed in radians. , was calculated from the following Euler's equation.

A video signal was recorded on the magnetic tape of each sample using a stick, a still image was reproduced, and the time until the reproduced image lost its sharpness was taken as a measured value as the still time.

To prevent powder from falling off, stretch a 20 cm piece of magnetic tape tightly onto a mirror-surfaced stainless steel plate with the magnetic layer facing up so that no sagging occurs, and fix both ends to the stainless steel plate with adhesive tape. Then, wrap Silbon paper around the tip and slide it over the tape with a metal rod designed to carry a load of 100g. After repeating this 500 times,
The presence or absence of magnetic powder adhering to the Silbon paper was visually observed. The evaluation is as follows.

○... No powder falling △... Some powder falling ×... Powder falling Example 2 In Example 1, fatty acid ester was used as n-Cl5H27C0OH and ec H2CH2C)I
A magnetic tape was prepared in the same manner except that the fatty acid ester consisting of z 011 was used, and the results were measured in the same manner as in Example ①, and the results are shown in Table 1.

Example 3 In Example 1, the fatty acid ester was changed to n -Cl5H27C0OH and <E>CIf Z C)
A magnetic tape was prepared in the same manner except that a fatty acid ester consisting of 12G H2OH was used. Table 1 shows the results of measurements made in the same manner as in Example 1.

Example 4 In Example 1, the amount of fatty acid ester used was
Magnetic tapes were prepared in the same manner as in Example 1, except that the M placement parts shown in the respective columns of Table 2 were used for 00 parts by weight.

Comparative Example 1 In Example 1, the conventional solid ester was used instead of the fatty acid ester. A magnetic tape was prepared in the same manner except that 1.5 parts by weight of the flIfk agent was used, and the results were measured in the same manner as in Example 1, and Table I shows the results.

Comparative Example 2 A magnetic tape was produced in the same manner as in Example 1, except that 1.5 parts by weight of higher fatty acid Mb acid ester using conventional leaf alcohol instead of fatty acid ester was used, and Example 1 was also applied to this magnetic tape. Table 1 shows the results of measurements made in the same manner as above.Blooming was observed in the magnetic layer.

Comparative Example 3 A magnetic tape was prepared in the same manner as in Example 1, except that 1.5 parts by weight of conventional silicone oil was used instead of the fatty acid ester, and the results were measured in the same manner as in Example 1. Shown in 1.

Comparative Example 4 Magnetic tapes were prepared in the same manner as in Example 1 except that the fatty acid ester was not used, and the results of measurements of these tapes in the same manner as in Example I are shown in Table 2.

From the results in the table above, it can be seen that the examples are better than the comparative examples.

〔Effect of the invention〕

According to the present invention, it is possible to provide a magnetic paint containing a linear fatty acid and a fatty acid ester obtained from hydrogenated cyclohexyl normal propanol, and to provide a magnetic recording medium using the same. , it is possible to provide a magnetic recording medium with good durability and good running stability, and in particular, it is possible to further improve these performances of a high-density recording type magnetic recording medium.

July 31, 1990

Claims (4)

[Claims] (1) A magnetic paint for forming a magnetic layer on a support, characterized by containing a fatty acid ester obtained from a straight chain fatty acid and hydrogenated cyclohexyl normal propanol. (2) The magnetic paint according to claim 1, wherein the number of carbon atoms in the straight chain fatty acid is greater than 10 and less than 18. (3) The magnetic paint according to claim 1 or 2, containing 1.5 to 6.0% by weight of a fatty acid ester obtained from a straight chain fatty acid and hydrogenated cyclohexyl normal propanol based on the magnetic powder. (4) A magnetic recording medium obtained using the magnetic coating material according to any one of claims 1 to 3.