JPS6352325A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To prevent tape squeaking and to improve color S/N by incorporating a specific arom. monocarboxylate into a magnetic layer. CONSTITUTION:This magnetic recording medium contains the arom. monocarboxylate compd. in the magnetic layer on a nonmagnetic base. The amt. of the arom. monocarboxylate compd. to be added to 100pts. magnetic material is 0.05-20pts. preferably 0.0-10pts. more preferably 0.5-5pts. The addition of the arom. monocarboxylate compd. to the magnetic layer in the process of production may be executed by impregnating said compd. into fine ferromagnetic powder of by top coating the same onto the magnetic layer before or after the dispersion of the fine ferromagnetic powder into a binder or after coating of the magnetic layer on the substrate. A thermoplastic resin, thermosetting resin or reaction type resin or the mixture composed thereof is used for the binder.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a magnetic recording medium, and more specifically, the magnetic layer has excellent surface properties, and is used in magnetic recording/reproducing decks that have increased in recent years. The present invention relates to a magnetic recording medium that has a small coefficient of friction with various materials when layers come into contact with each other and has excellent lubricity.

[Conventional technology]

In a magnetic recording medium that is not sufficiently lubricated, the surface of the magnetic layer becomes smooth due to contact with the contact portion of the magnetic recording/reproducing deck, increasing the coefficient of friction of the magnetic layer. A magnetic recording medium with an increased friction coefficient of the magnetic layer is particularly susceptible to the presence of minute water droplets in the contact area where the magnetic recording medium travels on the magnetic recording/reproducing deck under conditions of high humidity (relative humidity of 60% or more). An adhesion phenomenon occurs. When adhesion occurs at the running contact area between the magnetic recording medium and the recording/reproducing deck, if the running tension exceeds this adhesion force, the stick-
A running noise consisting of an audible sound is generated due to a slipping running sound. Furthermore, the recording signal of a magnetic recording medium that has undergone stick-slip running undergoes frequency modulation in the running direction, making it difficult to reproduce normal recording. Just in case, stick-slip running occurs during playback on a recorded magnetic recording medium.
Normal playback is not possible, causing phenomena such as wow and flange. Further, if the magnetic recording medium and the recording/reproducing deck come into contact with each other at the running contact portion, and the adhesion force becomes -1 less than the running tension during running, the running stops and recording/reproducing becomes impossible. In the industry, this is called "tape squeal," and the commercial value of such magnetic recording media and magnetic recording/reproducing decks is significantly inferior.

The cause of this tape squeal is the material, running tension, running speed, etc. of the magnetic recording medium running system in the magnetic recording/reproducing deck. In addition, in magnetic recording media, this is caused by the smoothing of the surface and the increase in the coefficient of friction.

Many solid and liquid lubricants are used to improve the surface lubricity of magnetic recording materials. Examples of such lubricants include inorganic and organic fine powders (At!O,...
Graphite, Silica, Orlog.

ZnO, carbon black, etc.) and organic surfactants (higher hydrocarbon compounds, aliphatic alcohols, fatty acids, fatty acid esters, fatty acid amides, fatty acid salts, fatty acid quaternary salts, etc.) are known, but the number of carbon atoms in these compounds is particularly limited. Those having a boiling point of about 100° C. or more and a melting point of about 150° C. or less are preferably used. These lubricants are added in an amount of 11 to 20 parts by weight per 100 parts by weight of the binder.

[Problems to be Solved by the Invention] However, even with the addition of these additives, it has been difficult to obtain magnetic recording having desirable characteristics. For example, when these additives are used in large amounts, the mechanical strength of the recording layer may be reduced. Furthermore, after the recording layer was formed, a phenomenon in which the additive gradually oozed out onto the surface of the recording layer was sometimes observed. Furthermore, the dispersion of the magnetic material was by no means satisfactory.

One of the lubricants known to date is aliphatic ester (butyl palmitate, etc.), but it is necessary to add an effective amount to the magnetic layer for the running of the stainless steel guide ball of the deck running system for magnetic materials. If added, tape squeal will occur in the deck head.

The present invention solves these drawbacks and provides a novel additive for magnetic layers.

A first object of the present invention is to provide a novel additive for a magnetic layer, thereby providing a magnetic recording material with excellent running properties. The second purpose is to provide a magnetic recording medium with improved magnetic properties and surface characteristics. The third object is to provide a magnetic recording medium with good sensitivity. The fourth object is to provide a magnetic recording material with good storage stability in which additives do not ooze out onto the surface of the recording layer.

[Means for solving problems]

That is, the present invention is a magnetic recording medium comprising a magnetic layer coated on a non-magnetic support, characterized in that the magnetic layer contains an aromatic monocarboxylic acid ester compound. .

The present invention will be explained in detail below.

The magnetic recording medium of the present invention basically has a magnetic recording medium on a non-magnetic support.
A magnetic layer containing an aromatic monocarboxylic acid ester and a ferromagnetic powder dispersed in a binder is provided.

The aromatic monocarboxylic acid ester compound used in the present invention is represented by general formula (1).

R' However, R represents an alkyl group having 1 to 18 carbon atoms, an alkyl group, an allyl group, or an aralkyl group. R' represents an alkyl group, halogen, halogenated alkyl group, carboxyl group, hydroxyl group, allyl group, aryl group, or aralkyl group.

Representative examples of compounds represented by general formula (1) include the following.

The aromatic monocarboxylic acid ester compounds used in this patent are not particularly limited to the above-mentioned A-1 to A-7 compounds, but those having a melting point of 100° C. or lower are preferred.

The ferromagnetic fine powder used in the present invention is γ-Fe10
3. Co-containing 7-Fe2O3, Fe3O4, Co-containing Fe3O4, Cr01, Co-N1-P alloy, Co
- Known ferromagnetic fine powder such as Ni-Fe alloy can be used,
Specifically, Japanese Patent Publication No. 44-14090, Japanese Patent Publication No. 14090, Publication No.
5-18372, Japanese Patent Publication No. 47-22062, Japanese Patent Publication No. 47-22513, Japanese Patent Publication No. 46-284
Publication No. 66, Special Publication No. 46-38755, Special Publication No. 4
Publication No. 7-4286, Japanese Patent Publication No. 47-12422,
Special Publication No. 47-17284, Special Publication No. 47-1850
9, Japanese Patent Publication No. 47-18573, etc. These magnetic substances are used in an amount of 50 to 2000 parts per 100 parts by weight (hereinafter "parts by weight") of the binder.

The amount of the aromatic monocarboxylic acid compound added to 100 parts of the magnetic material is [105 to 20 parts, preferably α1 to
The amount is 10 parts, more preferably 15 to 5 parts. In the manufacturing process, the aromatic monocarboxylic acid ester compound may be added by impregnating the ferromagnetic fine powder, or by coating it on the substrate before or after dispersing the ferromagnetic fine powder in the binder. It is also possible to overcoat the magnetic layer after it has been coated.

As the binder used in the present invention, conventionally known thermoplastic resins, thermosetting resins, reactive resins, and mixtures thereof are used.

The thermoplastic resin has a softening temperature of 150°C or less and an average molecular weight of 10,000 to 20,000. Degree of polymerization is about 200
~SOO level, such as vinyl chloride vinyl acetate copolymer, vinyl chloride vinylidene chloride copolymer, vinyl chloride acrylonitrile copolymer, acrylic acid ester acrylonitrile copolymer, acrylic acid ester vinylidene chloride copolymer, acrylic acid ester styrene copolymer,
Methacrylic acid ester 7-crylonitrile copolymer, methacrylic acid ester vinylidene chloride copolymer, methacrylic acid ester styrene copolymer, urethane nylastomer,
Nylon-silicon resin, nitro-heptylulose-bolyamide resin, polyvinyl fluoride, vinylidene chloride acrylonitrile copolymer, butadiene acrylonitrile copolymer, polyamide resin, polyvinyl butyral, cellulose derivatives (cellulose acetate butyrate, cellulose diacetate) , cellulose triacetate, cellulose propionone), nitrocellulose, etc.), styrene-butadiene copolymers, polyester resins, chlorovinyl ether acrylate copolymers, amine resins, various synthetic rubber-based thermoplastic resins, and mixtures thereof. etc. are used.

The uj values of these resins are given in Japanese Patent Publication No. 37-6877, 39.
-12528, 39-19282, 4゜-5349
No. 40-20907, No. 41-9463, 41-1
No. 4059, No. 41-16985, No. 42-6428,
No. 42-11621, As-4623, 43-152
No. 06, No. 44-2889, No. 44-17947, 44
-18232, 45-14020, 45-1450
No. 0, No. 47-18573, No. 47-22063, 47
-22064, 47-22068, 47-2206
No. 9, No. 47-22070, No. 47-27886, and the like.

The thermosetting resin or reactive resin has a molecular weight of 200,000 or less in the state of a coating liquid, and when heated after coating and drying, the molecular weight becomes infinite due to reactions such as condensation and addition. Moreover, among these resins, it is preferable that the resin does not soften or melt before it is thermally decomposed. Specifically, PJ, t haphenol resin, epoxy resin, polyurethane curable resin, urea resin, melamine resin, alkyd resin, silicone resin, acrylic reaction resin, epoxy-polyamide resin, nitrocellulose melamine resin, high molecular weight polyester resin. mixtures of incyanate prepolymers, mixtures of methacrylate copolymers and diisocyanate prepolymers, mixtures of polyester polyols and polyisocyanates, urea formaldehyde resins, mixtures of low molecular weight glycols/high molecular weight diols/triphenylmethane triisocyanates,
These include polyamine resins and mixtures thereof.

Examples of these resins are given in Japanese Patent Publication No. 39-+31 [) No. 3, 4.
No. 0-9779, No. 41-7192, No. 41-8016, No. 41-14275, No. 42-18179, 45-1
No. 2091, No. 44-28023, No. 45-14501, No. 45-24902, No. 46-13103, No. 47-2
No. 2065, No. 47-22066, No. 47-22067, No. 47-22072, No. 47-22073, No. 47-2
It is described in publications such as No. 8045, No. 47-28048, and No. 47-28922.

These binders may be used alone or in combination;
Other additives may be added as necessary.

The mixing ratio of the ferromagnetic powder and the binder is in the range of 10 to 200 parts by weight per 100 parts by weight of the ferromagnetic powder.

In addition to the above-mentioned components, additives such as a dispersant, a lubricant, and an abrasive may be added as necessary.

Examples of dispersants used as additives in the present invention include caprylic acid, capric acid, capric acid, myristic acid, palmitic acid, stearic acid, oleic acid, elaidic acid, linoleic acid,
Fatty acids with 12 to 18 carbon atoms (RICOOH) such as lyrinnic acid and stearolic acid.

R1 is an alkyl group having 11 to 17 carbon atoms).

Metal soaps made of alkali metals (Li, NaXK, etc.) or alkaline earth metals (MgXCa, Ba, etc.) of the aforementioned fatty acids; lecithin, etc. are used. In addition, carbon number 12
The above higher alcohols and their sulfuric esters can also be used. These dispersants are added in an amount of 1 to 20 parts by weight per 100 parts by weight of the binder.

For example, such a thing is
Publication No. 17945, Special Publication No. 17945, Special Publication No. 4B-
This is disclosed in US Pat. No. 15001, US Pat. No. 3,387,993, US Pat.

The lubricant is used for surface modification other than the purpose of addition of the aromatic monocarboxylic acid ester compound according to the present invention, and is made of carbon black of various sizes (average particle size 1
0-500mμ), silicone oil, graphite, molybdenum disulfide, tungsten disulfide, carbon number 12-1
Fatty acid esters consisting of 6 monobasic fatty acids and a monohydric alcohol with 3 to 12 carbon atoms, monobasic fatty acids with 17 or more carbon atoms, and a total of 21 to 12 carbon atoms in the fatty acids. Fatty acid esters consisting of 23 monohydric alcohols can be used. These lubricants are binder 100
It is added in an amount of 2 to 20 parts by weight. Regarding these, Japanese Patent Publication No. 43-23889,
They are described in Japanese Patent No. 42-28647, Japanese Patent No. 43-81543, Japanese Patent No. 47-28043, and US Pat. No. 42-233.

In this way, conventionally known fatty acid esters can also be used in magnetic recording media as long as they do not cause any actual harm.

Materials commonly used as abrasives include α-alumina,
Silicon carbide, chromium oxide, corundum, artificial corundum, diamond, artificial diamond, garnet, emery (main components: corundum and magnetite), etc. are used. These abrasives have an average particle diameter of CL05 to 5μ, particularly preferably 11 to 2μ. These abrasives have a bonding agent of 100i! 2 to 20 parts
It is added in a range of parts by weight. Regarding these, the special application
8-26749, US Pat. No. 3,687,725, and the like.

To form a magnetic recording layer (magnetic layer), the above-mentioned main components and additives are mixed in an arbitrary combination using an organic solvent, and the mixture is coated onto a support as a coating solution.

The organic solvents used for crosstalk and coating include ketones such as a7tone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone, methanol,
Alcohols such as ethanol, propa/-A/, and butanol: Ester systems such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, and acetic acid glycol monoethyl ether: Ethers, glycol dimethyl ether, glycol monoethyl ether, dioxane, etc. Glycol ether type: Tar type (aromatic hydrocarbons) such as benzene, toluene, xylene, etc.: Chlorinated hydrocarbons such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin, dichlorobenzene, etc. Can be used.

Examples of the nonmagnetic support used in the present invention include the following.

When used as a tape, the thickness of the support is 2.5 to 1
The thickness is about 00 μm, preferably about 3 to 40 μm. Further, in the case of a floppy disk, the thickness is preferably about 60 to 100 μm. Materials include polyesters such as polyethylene terephthalate and polyethylene naphthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate,
In addition to vinyl resins such as polyvinyl chloride, plastics such as polycarbonate, ceramics such as aluminum, copper, gold, glass, etc. are also used.

Methods for applying the magnetic coating liquid onto the support include air doctor coating, grade coating, air knife coating, squeeze coating, impregnation coating, reverse roll coating, transfer roll coating, gravure coating, kiss coating, cast coating, and spray coating. can be used, and other methods are also possible, and detailed explanations of these can be found in "Coating Engineering" published by Shokusen Shoten, pp. 253-277.
(published on March 20, 1972).

By such a method, the magnetic layer coated on the support is treated, if necessary, to orient all of the magnetic powder in the layer. dry. Also, is surface smoothing required? The entire magnetic recording body of the present invention is manufactured by cutting the magnetic recording material into a desired shape. These are disclosed, for example, in Japanese Patent Publication No. 40-23625, Japanese Patent Publication No. 39-28368, and US Pat. No. 3,473,960.

Furthermore, the method described in Japanese Patent Publication No. 41-13181 is a basic and important technique in this field.

〔Example〕

The present invention will be explained in more detail below with reference to examples. It will be readily understood by those skilled in the art that the components, proportions, order of operations, etc. shown herein may be modified without departing from the spirit of the invention.

Therefore, the present invention should not be limited to the implementation series described below.

Example 1 The following composition was thoroughly kneaded in a ball mill, and then added to 20 parts of Desmodur L-75 (trade name of a polyisocyanate compound manufactured by Bayer AG) and uniformly mixed and dispersed to prepare a magnetic paint.

CO-containing 1-lFezO3 powder (,e-1+=0%)
300 parts (Nitrogen adsorption specific surface area 40 m/?) (Powder Hc=70008) Vinyl chloride-vinyl acetate compound 20 parts (VMC!H, manufactured by Union Carbide) Nilaboran N
2304 40 parts (Japan Polyurethane) Carbon black 50 parts (average particle size 10 mm) Lecithin
1 part ester (X)
Y part lauric acid
Tripartite butyl acetate
60 parts methyl ethyl ketone 30
0 parts After adjusting the viscosity of this magnetic paint, it was applied onto the surface of a polyethylene terephthalate substrate, oriented, and dried to prepare a sample.

(Tape squeal) The number of times tape squeal is run on a tape deck is 30℃.
Driving repeatedly under 80%RH conditions? Row b1 The number of times the tape ran until the tape squeal occurred was determined.

(Flutter) 3 Measured with a Matsushita flutter meter by inputting an FJlz audio signal.

(Color S/N) Measuring device is Shibatsu KK noise meter (9zsc)
? A bypass filter of 10 KHz and a low-pass filter of 500 zAM were used. A Matsushita NY-8300 VTR was used. Based on the actual column (o an
) and compared.

〔Effect of the invention〕

As is clear from the above results, Samples 4 to 7 of the present invention containing an aromatic monocarboxylic acid ester in the magnetic layer are superior to Comparative Samples 1 to 3 in terms of tape squeal and color 8/N. .

Agent: Patent attorney (8107) Kiyotaka Sasaki (and 3 others) 1. Indication of the case: 1986 14 Revised Application No. 194073 2. Name of the invention: Name of recording medium: (5201 store) Shi Photo Film Co., Ltd. 5. Date of amendment order: (voluntary) 6. Number of inventions increased by amendment: 0 (1) On page 2, line 12 of the specification, [stick-slip] is changed to "stick-slip". to correct.

(2) In the same book, page 2, line 13, "flutter jitter" is corrected to "flutter, jitter."

(3) In the fifth line from the bottom of page 6 of the same book, "Ki 1 Kajigo" is amended to read "the present invention."

(4) On page 11, line 12 of the same document, "this patent" is amended to read "the present invention."

(5) Top right column of the table on page 19 of the circular, 'C/S N
Correct J to "C/SN".

1 Temple 8pm Chief'￥-f Hall 1. Incident display 1985 retention 1. 'F Application No. 19107 March 2, Title of invention Name of magnetic recording medium: (520) Hatashi Photo Film Co., Ltd. 6, Attack on inventions increased by amendment 207, Countermeasures for amendment:

Claims (1)

[Claims] 1) A magnetic recording medium comprising a magnetic layer coated on a non-magnetic support, characterized in that the magnetic layer contains an aromatic monocarboxylic acid ester compound.