JPS60129926A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having excellent running performance by incorporating fatty acid, fatty ester and specific alkoxy silane into a magnetic recording layer. CONSTITUTION:Fatty acid, fatty ester and the alkoxysilane expressed by the formula 1 are incorporated into a magnetic recording layer. R in the formula 1 denotes 1-5C alkyl group, phenyl group or substd. phenyl group, R' denotes 1- 5C alkyl groups, m=1-3, n=0-2, m+n=1-3. The amt. of the fatty acid to be added is made preferably in the range of 1/3-1/5 the amt. of the fatty ester to be used in combination. The amt. of the fatty ester is made preferably 4- 6pts.wt. by 100pts.wt. the binder resin constituting the magnetic recording layer. The alkoxysilane expressed by the formual 1 has the effect of improving the water repellency of the magnetic recording layer and exhibiting stably the lubricity at low and middle speeds up to a high speed of the fatty acid and fatty ester at and under a high temp. and high humidity. The amt. of the alkoxysilane is preferably is made in the range of 1-3pts.wt. by 100pts.wt. the binder resin.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to improvements in magnetic recording media.

[Technical background of the invention and its problems]

The magnetic layer of a magnetic recording medium, such as a magnetic tape, usually comprises a magnetic material, a binder resin, a dispersant, an abrasive, an antistatic agent, a lubricant, a hardening agent, and other additives. When these magnetic tapes are used in recording and reproducing devices such as cassette decks and VTRs, they run in contact with magnetic heads, tape guides, cylinders, etc., so the friction coefficient of the tape is small and the tape runs smoothly and stably. It is required to have gender. In other words, it is necessary to prevent "snapping" on music tapes and "pajitter" on video tapes.When a magnetic tape runs, the tension of the tape and the contact area between the magnetic layer and the magnetic head, tape guide, cylinder, etc. If the coefficient of friction becomes large due to conditions such as running speed, the tape will vibrate, causing the aforementioned disadvantageous phenomenon.

Furthermore, the recent development of VTRs has been remarkable and they have become multi-functional, and models have been developed that have all of the user's requirements, such as methyl mechanism, slow speed, double speed playback, etc. Along with this, the requirements for magnetic tapes from the equipment side are also increasing. That is, for slow speed and playback, stable running performance of the magnetic tape is required from low speed to high speed.

For this reason, magnetic paints to which lubricants such as higher fatty acids, their esters, fluid/rough-in, fluorinated oils, silicone oils, graphite powders, etc. have been added have been applied onto the support. A magnetic tape is known in which a magnetic layer is formed by applying a magnetic layer to the magnetic layer. However, even these lubricants are still unable to impart sufficient lubricity to the magnetic layer of a magnetic tape, resulting in stable running, especially under high temperature and high humidity environments (e.g., 30°C to 60°C, 70° to 90% RH). It was difficult to ensure sex.

[Purpose of the invention]

The present invention aims to provide a magnetic recording medium that has stable running performance from low speeds to high speeds even under high temperature and high humidity conditions.

[Summary of the invention]

The present invention provides a magnetic recording medium comprising a magnetic recording layer provided on a non-magnetic support, in which the magnetic recording layer contains a fatty acid, a fatty acid ester, and a general formula [However, in the formula, RtdC□ to C3 are alkyl groups, phenyl groups, Substituted phenyl group, R' is C□-C6 alkyl group, m = 1-3, n = 0-2, m + n = 1-3
The main objective of the present invention is to obtain a magnetic recording medium having excellent running performance as described above by incorporating an alkoxysilane represented by the following formula.

Examples of the non-magnetic support include polyester film.

The above magnetic recording layer includes ferromagnetic powder, binder resin, dispersant,
Contains abrasives and antistatic agents.1. Moreover, it is formed by a magnetic paint containing the above three components.

The ferromagnetic powder used here is, for example, Fe2O3.
Magnetic iron oxide powder, Cr0□ powder, Fe-Co powder, Ba-ferrite powder, substituted Ba-ferrite powder, and other magnetic tapes can be used in general. Examples include magnetic powder. As the binder resin, for example, vinyl chloride-vinyl acetate copolymer, nitrocellulose, cellulose derivatives, polyurethane, polyester, etc. are used. As the polishing agent, for example, Cr2O3rAl2O3 or the like is used.

The above fatty acids exhibit a lubricating effect at relatively low speeds.

Such fatty acids (d may be either saturated or unsaturated, and specific examples include casorylic acid, capric acid, lauric acid, myristic acid, valmitic acid, stearic acid, oleic acid, etc.) Addition of such fatty acids 34klrJ Fatty p2 esters 1/1 to 1/10 of the relief, preferably 1/1 of
It is desirable to set it in the range of 3 to 115. The reason for this is that if the amount of fatty acid added is less than 1/10 of the amount of fatty acid ester, the magnetic recording medium tends to stick to the magnetic head when the magnetic head rotates at low speed. When it exceeds 1, fatty acids tend to precipitate in the form of fatty acid salts, which may lead to deterioration in image quality.

The above fatty acid ester exhibits a lubricating effect at relatively medium to high speeds. Such fatty acid esters may be either saturated or unsaturated, and specifically include methyl stearate, ethyl stearate, butyl stearate, methyl myristate,
It is desirable to use 05 to 10 parts by weight, preferably 4 to 6 parts by weight, based on butyl laurate, methyl oleate, and butyl palmitate. The reason for this is that if the amount of fatty acid ester added is less than 0.5 parts by weight, sufficient lubrication effect at medium to high speeds cannot be achieved;
If the amount exceeds 0 parts by weight, the fatty acid ester itself oozes out, resulting in unstable running properties and image fluctuations.

The alkoxysilane represented by the above general formula increases the water repellency of the magnetic recording layer, and has the effect of stably exhibiting the low-speed, medium-to-high speed wet magnetism of the fatty acids and fatty acid esters at high temperatures and high humidity. have Examples of such alkoxysilane include methylhydroxydimethoxysilane,
Examples include ethyldihydroxymonoethoxysilane, methyltrihydroxysilane, methyldihydroxy-septamine biloboxysilane, and 5 parts by weight, preferably 1 part by weight.
It is desirable to keep it in the range of ~3x triplet. The reason for this is
When the amount of alkoxysilane added is 0.2 r+i parts by weight, the effect of improving water repellency (moisture repellency) can be fully exhibited (although the amount is 5 parts by weight). If it exceeds this, there will be bleeding into the surface of the magnetic recording layer, which will degrade the running B, which is not desirable.

Next, a manufacturing method for obtaining the magnetic recording medium of the present invention will be briefly described.

First, ferromagnetic powder, binder resin, dispersant, abrasive, antistatic agent, etc. are thoroughly kneaded using, for example, a three-roll mill, bow/l/mill, sand grinder, kneader, etc., and then the hardening agent is added to the kneaded mixture. and further add and mix the fatty acid, fatty acid ester, and alkoxysilane to prepare a magnetic paint.

Next, this magnetic paint is applied onto a non-magnetic support such as a polyester film by aired coater coating, plate coating, nice edge coating, reverse roll coating, transfer roll coating, gravure coating, etc. After drying, surface forming treatment is performed. (Calendar treatment) to form a magnetic recording layer and manufacture a magnetic recording medium.

According to the present invention, the present invention contains a fatty acid that is highly effective for lubrication at relatively low speeds, a fatty acid ester that is highly effective for lubrication at relatively medium to high speeds, and an alkoxysilane of a general formula that is highly effective for water repellency. By this, it is possible to obtain a magnetic recording medium that has smooth and stable running performance from low to high speeds, particularly under high temperature and high humidity conditions, and has improved "jitter" and "jitter" during running.

[Embodiments of the invention]

Next, the present invention will be explained in detail.

Examples 1 to 8 First, Ba-ferrite powder substituted with Ti and Co (average particle size 0.1 μm 1 coercive force; 800 (:0e
l) 100 parts by weight, vinyl-vinyl acetate copolymer 5
Weight department, month? In the presence of 120 parts by weight of methyl ethyl ketone and 60 parts by weight of toluene, 10 parts by weight of urethane tung fat, 4 parts by weight of Noblak, 2032.5 parts by weight of Cr, and 2 parts by weight of lecithin were used in a dispersing machine (sand grinder). Distributed processing. Subsequently, after filtration was performed to remove dust during dispersion treatment and fragments of dispersion media, polyisocyanate was added to the resin in an amount of 2 ooms. Subsequently, fatty acids, fatty acid esters, and alkoxysilanes shown in Table 1 below were added, and the mixture was thoroughly stirred.
By mixing, 11 kinds of magnetic paints were prepared.

Next, each of the above-mentioned magnetic paints was applied onto a polyethylene terephthalate film, dried, and subjected to surface treatment with a super calendar, and then cured at 60 ° C. for 2 days.
Furthermore, cut into 10.4 inch width pieces? Magnetic tape samples (Examples 1 to 8 and Comparative Examples 1 and 2) were manufactured.

Thus, the obtained magnetic tape samples of Examples 1 to 8 and Comparative Example 1.2 were tested at 25° C., at a running speed of 5+ nm/sec under 40% RII, and at a running speed of 20 lIr.
Surface friction coefficient (μKl) p (μKz) at m/see and running speed 300 ham/sec
+ (3 for μ), and running speed 5 mn/sec at 35°C and 88 inches, running speed 20 mm/
The surface friction coefficients (1 in μ), 2 in μ, and 3 in μ at a running speed of 300 rrm/see were measured. The results are shown in Table 2 below. The friction coefficient (μK) is measured using T/T o = e *, p AKQ [however, To:
Measured tension (3'Og), T: tension during running, Q: constant].

In addition, for each magnetic tape sample, 35°C, 88%
The thickness was measured and is also listed in Table 2. Jitter was measured at β-■ mode speed at 35° C. and 88%.

Furthermore, when the humidity dependence of the friction coefficient was investigated for Examples 3 and 7 and Comparative Examples 1 and 2, the characteristic diagram shown in FIG. 1 was obtained. In addition, A3 in the figure is the characteristic line of the magnetic tape sample of Example 3, A7 is the characteristic line of the same sample of Example 7, and B1
B2 is the characteristic line of the same sample of Comparative Example 1, and B2 is the characteristic line of the same sample of Comparative Example 2. When the speed dependence was investigated, the characteristic diagram shown in FIG. 2 was obtained. In addition, A in Figure 2
3 is a characteristic line of the magnetic tape sample of Example 3, and B2 is a characteristic line of the same sample of Comparative Example 2.

As is clear from Table 2 and Figures 1 and 2, Comparative Example 1
, 2 shows a significant decrease in running performance at high humidity and high speed. On the other hand, it can be seen that the magnetic tape samples of Examples 1 to 8 have small speed dependence and excellent running properties even under high humidity.

〔Effect of the invention〕

As described in detail above, the present invention provides a sharpened recording medium that has stable running performance from low speeds to high speeds even under high temperature and high humidity conditions and has improved "jitter" and "jitter" during running. Can be provided.

[Brief explanation of drawings]

FIG. 1 is a characteristic diagram showing the humidity dependence of the friction coefficient of the magnetic tape samples in Examples 3 and 7 and Comparative Examples 1 and 2;
FIG. 2 is a characteristic diagram showing the speed dependence of the friction coefficient of the air-rupture tape samples in Example 3 and Comparative Example 2.

Claims (2)

[Claims] (1) In a magnetic recording medium comprising a magnetic recording layer provided on a non-magnetic support, the magnetic recording layer contains a fatty acid, a fatty acid ester and the general formula % formula % (( ) [However, R in the formula is C, - Alkoxysilane represented by a C5 alkyl group, phenyl group or substituted phenyl group, R/ is a C1 to C5 alkyl group, m-1 to 3. n = 0 to 2 and m + n = 1 to 3] A magnetic recording medium characterized by containing. (2) The magnetic recording medium according to claim 1, wherein the fatty acid is selected from C7 to CTE acids.