JPS63220419A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having low starting torque and low kinematic friction by incorporating two or more kinds of glycerol esters of 10-30C fatty acids into a magnetic layer. CONSTITUTION:A prescribed lubricating effect is produced on a magnetic layer by using a mixture of glycerol esters of 10-30C (un)satd. fatty acids as a lubricant. A combination of the esters with olive oil and fatty acids is preferably used so as to reduce the starting torque and kinematic friction. The fatty acids are generally used in about 10:1-1:10 ratio to the glycerol ester mixture. The magnetic layer is hardly scratched, the falling of powder is suppressed and the durability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to magnetic recording media such as magnetic tapes, magnetic sheets, and magnetic disks.

[Conventional technology]

Generally, magnetic recording media such as magnetic tapes are manufactured by applying a magnetic paint made of magnetic powder, binder resin, etc. onto a support and drying it.

In such magnetic recording media, it is known to use a lubricant as an additive to the magnetic layer.

The purpose of this is the magnetic layer 0111? The object of the present invention is to provide a magnetic recording medium with improved # properties and abrasion resistance, and excellent running stability and durability.

Until now, various lubricants (for example, monobasic fatty acids with a carbon number / - ~ l) and monobasic fatty acids with a total number of carbon atoms of - - lubricants have been used to reduce the friction of magnetic layers. It is known to add fatty acid esters consisting of three monohydric alcohols, fatty acids such as oligophosphoric acid and myristic acid, silicone oil, fluorides, graphite, molybdenum disulfide, etc.). however.

Even with the addition of these lubricants, sufficient properties have not yet been obtained, and in particular, undesirable phenomena such as sticking cannot be prevented.

For example, JP-A-4/-412733 discloses that when a lubricant system containing a combination of fatty acids and fatty acid esters and in which fatty acid/fatty acid ester = J or more is used, running stability is improved.
It is disclosed that still durability is significantly improved.

On the other hand, Japanese Unexamined Patent Application Publication No. 2003-111003, No. 741 states that a magnetic recording medium containing an organic silicone compound has improved durability and running stability.

However, in lubricant systems such as those mentioned above.

The starting torque (friction at the beginning of running) cannot be kept low, resulting in head noise, tension between the recording medium and the head, which adversely affects the magnetic layer, causing output fluctuations, dropouts, etc. In addition, the lubricant for the magnetic layer has been actively researched, but it is still insufficient, and improvements have been desired. One object is to provide a magnetic recording medium with low starting torque and low dynamic friction.

A first object of the present invention is to provide a magnetic recording medium to which a lubricant is added which can provide high lubricity with a small amount.

A third object of the present invention is to provide a magnetic recording medium that improves running stability, durability, etc., and reduces output fluctuations, head noise, etc. by achieving one or more of the objects. be.

[Structure of the invention]

As a result of intensive research to achieve the above object, the inventor has found that 0. A mixture of glycerin esters of saturated and unsaturated fatty acids of ・〜C,・ is used as a lubricant Vcv! It was discovered that a predetermined lubricating effect can be achieved when used in this manner, leading to the present invention.

The gist of the present invention resides in a magnetic recording medium containing two or more kinds of glycerin esters of fatty acids having 10 to 30 carbon atoms in a magnetic layer.

The present invention will be explained in more detail below.

Glycerin esters of fatty acids are OI・~ as a compound.
It is obtained by esterifying aSS fatty acids such as laflic acid, myristic acid, stearic acid, oleic acid, norylic acid, sardine acid, and lysyllic acid with glycerin.

It also exhibits slippery properties as a natural product due to mixed glycerin ester.

When the mixture of glycerin esters used in the present invention is contained in the magnetic layer, it is used together with at least the magnetic powder and the binder resin.

For these magnetic powders and binder resins, magnetic powders and resins such as Σ described later are used, and the amount of binder resin used is 3 to 300 parts by weight per 100 parts by weight of magnetic powder, preferably t to ljO. Using parts by weight may lead to unfavorable situations such as a decrease in magnetism in terms of mechanical strength and the like. The ratio of the above glycerin ester (mixture) used for such magnetic powder and binder tree JiiK is 1 part of the magnetic powder.
00i! It is preferably 0.7 to 0 parts by weight based on parts by weight,
More preferably, the amount of the glycerin ester added is in parts by weight of o, r to IO.If the amount of the glycerin ester added is too large, it will cause a decrease in the mechanical strength of the coating film or cause a blooming phenomenon, and if it is too small, the lubricating effect and wear resistance will deteriorate. The effect does not appear.

The above-mentioned mixture of glycerin esters used in the present invention can be used alone, but as described below, it can be used in combination with other lubricants, fatty acids, silicone oil, fluorine oil, paraffin, squalane lubrication, or two or more of these. This will result in a significant improvement in lubricant performance. Particularly, the combination of olive oil/fatty acid is preferable for reducing starting torque and dynamic friction. The amount of fatty acid used is usually about to:t-t:lo based on the glycerin ester mixture.

In the present invention, the magnetic powder used for the nonmagnetic layer Vcll' includes 7"-Fe, O,, oor F8mOn,
? 61104. oo-Ire@04,0rbs
Oxide magnetic powder such as Fe, Ni%Co.

Fe-Ni alloy, Fe-N1-P alloy, lFF-Ni-
Examples include various magnetic powders such as metal magnetic powders such as 00 alloy.

Orthogonal heptadite powder such as barium ferrite and iron nitride can also be used.

Examples of the binder resin include thermoplastic resins, thermosetting resins, reactive resins, electron beam curable resins, and mixtures thereof.

Specifically, the thermoplastic resin is vinyl chloride-vinyl acetate-vinyl alcohol copolymer.

Vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, acrylonitrile-butadiene copolymer, polyvinyl butyral, nitrocellulose, cellulose derivatives such as acetylcellulose, polyester resin, thermosetting resin, etc. Reactive resins include phenolic resin, phenoxy resin, and epoxy resin.

Polyurethane resin etc. are used.

As an electron beam curing resin! Examples include 7-rethane acrylic type and polyester acrylic type.

These binders are used alone and in mixtures.

Further, a curing agent may be used to crosslink the binder, and incyanates that can be used include tolylene diincyanate, #,4t'-diphenylmethane diincyanate, hexamethylene diincyanate, inphorone diincyanate, and these incyanates. Examples include adducts of cyanate and active hydrogen compounds.

The magnetic paint forming the magnetic layer may contain additives such as a dispersant, an antistatic agent, and an abrasive, if necessary.

For example, as a dispersant, lecithin, higher alcohol,
Various fatty acids, their metal salts, and commercially available surfactants can be used. These dispersants may be used alone or in combination of two or more types.

Abrasives include fused alumina and silicon carbide.

Chromium oxide, corundum, titanium dioxide, diamond, garnet, emery, etc. are used.

Further, examples of the antistatic agent include carbon black and graphite.

The solvents used in the above paints include ketones such as acetone, cyclohexanone, methyl ethyl ketone, and methyl isobutyl ketone; aromatic hydrocarbons such as benzene, toluene, and xylene; ethers such as dioxane and tetrahydrofuran; alcohols such as methanol and ethanol; Esters such as ethyl acetate and butyl acetate, halogenated hydrocarbons such as methylene chloride and chloroform, etc. can be used.

Preferred ranges for specific blending ratios of these compositions include 50-tOtik parts of magnetic powder, ~20t-1ik parts of polyurethane binder resin, and other binder resins (20-tOtik parts).
Can be used in combination with more than one species) -~-〇 parts by weight, curing agent/~ Jjt amount part 1 dispersant 0.1~! parts by weight, abrasive 0.7-6 parts by weight,
The amount of antistatic agent J is approximately 13 parts by weight.

〔Effect of the invention〕

According to the present invention, the use of the above-mentioned mixture of glycerin esters improves the lubricating effect compared to conventional lubricants. That is, the magnetic layer is less likely to be scratched or powder falls off, leading to improved durability. It is also possible to significantly reduce output fluctuations, head noise, etc.

〔Example〕

Next, the present invention will be described in detail, but the present invention is not limited thereto unless it exceeds the gist thereof.

QO containing 1-Pa, O, powder 63'
H23011 (Polyurethane manufactured by Nippon Polyurethane)
I 0VAGH (UOO salt vinyl acetate) 13 Lecithin l Carbon black! Alumina l Olive oil 3 Cyclohexanone Riyo Toluene Ri! Methyl ethyl ketone! After mixing and dispersing the above components in a ball mill for about at hours, Coronate L (Japan Polyurethane) was dispersed as a hardening agent.The above magnetic paint was applied onto a 7 μm thick polyester film to a dry thickness of 1 μm and dried to give a mirror finish. After processing,
A magnetic disk of the present invention was obtained by punching out a predetermined disk. The starting torque and dynamic friction force of the obtained disc were measured, and the results are shown in Table 1.

Example A magnetic disk was obtained in the same manner as in Example 1, except that the same amount of mustard oil was used instead of co-olive oil.

Example 3 A magnetic disk was obtained in the same manner as in Example except that the same amount of olive silacric acid (weight ratio = 3/l) was used instead of olive oil alone.

Example: i7c nitrocellulose instead of VAGH in Example 1 (trade name Cell Line FM-〇〇 manufactured by Daicel Chemical Industries)
A magnetic disk was obtained in the same manner as in Example 1, except that the same amount of was used.

Example A magnetic disk was prepared in the same manner as in Example 1, except that the same amount of metal powder (trade name MAP-100, manufactured by Kanto Denka Rise) was used in place of the 00-containing 1-Fe and Ol in Example 1. Obtained 90 Example 6 Barium ferrite powder (trade name HEX-23 manufactured by Toda Kogyo Co., Ltd.) was used instead of 9 for 00-containing 7''-Fe, O, in Example /.
A magnetic disk was obtained in the same manner as in Example except that the same amount of was used.

Comparative Example 1 A magnetic disk was obtained in the same manner as in Example 1, except that the same amount of butyl stearate was used in place of the olive oil in Example 1.

Comparative Example A magnetic disk was obtained in the same manner as in Example 3 except that the same amount of butyl stearate was used in place of the olive oil in Example 3.

Comparative Example 3 A magnetic disk was obtained in the same manner as in Example D, except that the same amount of butyl stearate was used in place of the olive oil in Example D.

Comparative Example Tei Example! A magnetic disk was obtained in the same manner as in Example except that the same amount of butyl stearate was used instead of olive oil.

Comparative example! A magnetic disk was obtained in the same manner as in Example 6 except that the same amount of butyl stearate was used in place of the olive oil in Example B.

As is clear from the table above, friction can be significantly reduced by using glycerin ester of mixed fatty acids such as olive oil. Starting torque (measured with a torque meter) Maximum static friction at the beginning of disk rotation Force<II-cm) Dynamic friction (Measure the current flowing through the disk drive spindle motor with a current probe.) Dynamic friction force when the disk rotates (Load applied to the motor: fiA) Applicant: Mitsubishi Chemical Industries, Ltd. Agent Patent Attorney Hase - (7 others)

Claims (3)

[Claims] (1) A magnetic recording medium containing two or more kinds of glycerin esters of fatty acids having 10 to 30 carbon atoms in a magnetic layer. (2) The magnetic recording medium according to claim 1, wherein the glycerin ester of fatty acid is a mixture, and the mixture is olive oil. (3) The magnetic recording medium according to claim 1, which further contains a fatty acid and two or more kinds of glycerin esters of fatty acids.