JPS5823648B2 - Shinkinajikikirokutai - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording body, and particularly to a back layer provided on the side of the support of the magnetic recording body opposite to the side on which the magnetic recording layer is provided (hereinafter referred to as the back surface of the support). (back layer) composition.

In recent years, the performance of magnetic recording media has gradually improved, but as tapes for high-density recording (magnetic recording with extremely high recording density per unit area of the magnetic recording surface) such as video tape become popular. Nowadays, not only the physical or mechanical properties of the magnetic surface but also the charging and scratches on the back surface of the support have become a problem.

This is because dust generated by scratches on the support surface or dust entering from the outside adheres to the back surface of the support due to static electricity.
This is because when the magnetic tape is wound, such dust is transferred to the magnetic layer, and this dust causes a so-called "one dropout" in which signals are dropped during recording or reproduction.

Therefore, in order to prevent such dropouts, magnetic recording tapes have been manufactured in which a suitable back layer is provided on the back side of the support.

The composition proposed for the back layer consists of one or more inorganic or organic powders dispersed in a binder consisting of a film-forming resin, which is applied.

Examples of powders include carbon black, hematite, mica, silica gel, magnesium oxide, zinc sulfide, tungsten carbide, boron nitride, graphite, starch, zinc oxide, kaolin, talc, clay, lead sulfate, barium carbonate, calcium carbonate, carbonate. Macnesium, boehmite (γ
-A100H), alumina, tungsten sulfide, titanium oxide, poly(tetrafluoroethylene) powder, polyethylene powder, polyvinyl chloride powder, metal powder, etc.

When a good electrical conductor such as carbon black is contained in the back layer of the magnetic recording material, the charging property of the magnetic recording material can be further significantly reduced.

Further, in the case of a tape-shaped magnetic recording medium, it is possible to prevent the winding from breaking when the magnetic recording medium is wound, thereby stabilizing the feeding of the tape.

However, in recent years, similar to the case of the magnetic recording layer, a high level of durability, especially abrasion resistance, has been required for this back layer.

If only carbon black is used as the powder, the abrasion resistance of the back layer tends to deteriorate even though the antistatic properties are excellent.

In order to improve these properties, a method of using carbon black in combination with aluminum oxyhydroxide, magnesium carbonate, or calcium carbonate was already proposed in the 4th year of the Special Publication.
It is described in Publication No. 9-8321.

On the other hand, when using a videotape, etc., marks may be made on the back layer with a pen or the like in order to visually check the recording location, but in such cases, the color tone of the back layer should be as bright as possible. This is desirable.

The inventors of the present invention have conducted various studies on methods for obtaining a back layer with excellent wear resistance, charging properties, and marking properties.
Invented a back layer with a new composition that has such characteristics,
This has led to the present invention.

That is, the present invention provides a magnetic recording material in which a magnetic recording material is provided on one side of a film-like support and a back layer in which powder is dispersed in a binder is provided on the other surface. The present invention relates to a magnetic recording material containing at least one type of antimony fine powder as a powder.

The antimony-based fine powders suitable for use in the present invention include diantimony trioxide (Sb203), monoantimony(III) oxychloride (SbOCl), antimony pentaoxydichloride (Sb, O, CI□), and oxy-antimony Antimony oxide (I[I) (SbOBr ), antimony pentaoxydibromide (Sb40.Br2), antimony oxyiodide (SbOI), antimony pentaoxydiiodide (5
b4o5I2), etc.

These antimony-based fine powders have a particle size of 15μ or less, especially 8
A range of μ to 0.02 μ is desirable.

It has been found that if it is less than this range, the surface when used as a back layer becomes too rough, and if it is less than this range, the hiding rate as a pigment decreases and the marking properties deteriorate.

Of course, if the marking characteristics are not a problem, it may be finer.

When only antimony-based fine powder is used as the fine powder contained in the back layer, the back of the tape becomes a beautiful white color, which is extremely suitable for writing marks such as memos.

Furthermore, when the antimony-based fine powder of the present invention is used in combination with carbon black, the abrasion resistance is improved compared to when carbon black is used alone, and the color of the back layer becomes brighter and grayer, so the marked areas are It is easier to read visually.

Carbon black 100 when considering antistatic properties
It is preferable to use 10 to 300 parts by weight of the antimony-based fine powder per part by weight.

It has been found that below the lower limit, the abrasion resistance tends to decrease, while above the upper limit, the charging property increases and dropout is likely to occur.

Regarding antistatic properties, antimony beoxyhalide is more effective than diantimony trioxide.

It has also been found that the present invention reduces the risk of fire during the magnetic coating manufacturing process.

The above-mentioned fine powder is used in combination with a thermoplastic or thermosetting binder, and 20 to 4
It is used in a range of 0.00 parts by weight.

Below the lower limit, charging tends to occur, and above the upper limit, wear resistance tends to decrease.

In the present invention, the back layer is preferably provided on the support with a thickness of 0.6 to 10 microns, particularly 1.0 to 8 microns.

The back layer is provided by combining the above fine powder with a binder, adding other additives as appropriate, kneading it with a coating solvent, and coating it on the support.

Examples of additives include the powder for the back layer described above (pages 2 and 3), abrasives, dispersants, antistatic agents, and the like.

Regarding the back layer coating, e.g. No. 2804401, No. 3293066, and No. 3293066.

No. 3617378, No. 3062676, No. 37347
No. 72, No. 3476596, No. 2643048, No. 2803556, No. 2887462, No. 29236
No. 42, No. 2997451, No. 3007892, No. 3041196, No. 3115420, No. 31666
No. 88, etc.

As the binder, the following can be used.

As a thermoplastic resin, the softening temperature is 150°C or less, the average molecular weight is 1oooo to 200,000, and the degree of polymerization is about 200 to 2.
For example, vinyl chloride vinyl acetate copolymer, vinyl chloride vinylidene chloride copolymer, vinyl chloride acrylonitrile)v copolymer, acrylic acid ester acrylonitrile copolymer, acrylic acid ester vinylidene chloride copolymer , acrylic acid ester styrene copolymer,
Methacrylic acid ester acrylonide IJ copolymer, methacrylic acid ester vinylidene chloride copolymer, methacrylic acid ester styrene copolymer, urethane elastomer, polyvinyl fluoride, vinylidene chloride acrylonitrile copolymer, butadiene acrylonitrile copolymer Polymers, polyamide resins, polyvinyl butyral, cellulose derivatives (
cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose, etc.), styrene butadiene copolymer, polyester resin, chlorovinyl ether acrylate copolymer.

Amine resins, various synthetic rubber-based thermoplastic resins, mixtures thereof, and the like are used.

Examples of these resins are given in Japanese Patent Publication No. 37-6877, 39-
No. 12528, No. 39-19282, No. 40-5349, No. 40-20907, No. 41-9463, No. 41-14
No. 059, No. 41-16985, No. 42-6428, 4
No. 2-11621, No. 43-4623, No. 43-1520
No. 6, No. 44-2889, No. 44-17947, 44-
No. 18232, No. 45-14020, No. 45-14500
No., 47-18573, 47-22063, 47-
No. 22064, No. 47-22068, No. 47-22069
No. 47-22070, No. 48-27886, US Pat. No. 3,144,352-US Pat. No. 3,419,420: US Pat.
No. 789; described in No. 3713887.

As a thermosetting resin or a reactive resin, it has a molecular weight of 200,000 or less in the state of a coating liquid, and when added after coating and drying, the molecular weight increases by reactions such as condensation and addition.

Also, among these resins, those that do not soften or melt before the resin is thermally decomposed are preferred.

Specifically, for example, phenol resin, epoxy resin, polyurethane curable resin, urea resin, melamine resin, alkyd resin, silicone resin, and acrylic reactive resin.

Mixtures of high molecular weight polyester resins and incyanate prepolymers, mixtures of methacrylate copolymers and diinocyanate prepolymers, mixtures of polyester polyols and polyincyanates, urea formaldehyde resins, low molecular weight glyco-/Lz.

These include mixtures of high molecular weight diols/triphenylmethane triisocyanate, polyamine resins, and mixtures thereof.

Examples of these resins are given in Japanese Patent Publication No. 39-8103, 40-
No. 9779, No. 41-7192, No. 41-8016, 4
1-14275, 42-18179, 43-120
No. 81, No. 44-28023, No. 45-14501, 4
5-24902, 46-13103, 47-220
No. 65, No. 47-22066, No. 47-22067, 4
No. 7-22072, No. 47-22073, No. 47-280
45, 47-28048, 47-28922, U.S. Pat. No. 3144353; U.S. Pat. No. 3320090; U.S. Patent No. 34
No. 37510; No. 3597273: No. 3781210
No. 3781211.

These binders may be used alone or in combination.

As a dispersant, fatty acids having 12 to 18 carbon atoms (R, CoOH) such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, elaidic acid, linoleic acid, linonic acid, stearolic acid, etc. ，
R1 is an alkyl group having 11 to 17 carbon atoms); a metal soap consisting of an alkali metal (Li, Na, etc.) or an alkaline earth metal (Mg, Ca, Ba) of the above fatty acid;
Lecithin etc. are used.

In addition, higher alcohols having 12 or more carbon atoms and sulfuric esters may also be used.

These dispersants are used in an amount of 1 to 20 parts by weight per 100 parts by weight of the binder.
It is added in a range of parts by weight.

Examples include Special Publication No. 39-28369, No. 44-17
No. 945, No. 48-15001, U.S. Patent No. 33879
It is described in No. 93; No. 3470021, etc.

Commonly used abrasive materials include fused 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 0.05 to 5 .mu.m, particularly preferably 0.1 to 2 .mu.m.

These abrasives are used in an amount of 7 to 20 parts by weight per 100 parts by weight of the binder.
It is added in a range of parts by weight.

Regarding these, Japanese Patent Publication No. 48-26749 (Japanese Patent Publication No. 52-28642), U.S. Patent No. 300780
No. 7: No. 3041196, No. 3293066; No. 3
No. 630910, No. 3687725; British Patent No. 114
No. 5349; West German patent (DT-PS) 853211
listed in the number.

Graphite, carbon black,
Conductive powders such as carbon black grafted polymers;
Natural surfactants such as saponins; nonionic surfactants such as alkylene oxides, glycerols, and glycidols; cationic interfaces such as higher alkylamines, quaternary ammonium salts, pyridine and other heterocycles, and phosphoniums or sulfoniums. Active agent: Anionic surfactant containing acidic groups such as carboxylic acid, sulfonic acid, phosphoric acid, sulfuric acid ester group, and phosphoric ester group; Ampholytic surfactants such as amino acids, amino acids, aminosulfonic acids, and sulfuric or phosphoric acid esters of amino alcohols Activators and the like are used.

Some examples of surfactant compounds that can be used as antistatic agents are disclosed in U.S. Pat.
No. 2288226, No. 2676122, No. 26
No. 76924, No. 2676975, No. 2'69156
No. 6, No. 2727860, No. 2730498, No. 2
No. 742379, No. 2739891, No. 306810
No. 1, No. 3158484, No. 3201253, No. 3
No. 210191, No. 3294540, No. 341564
No. 9, No. 3441413, No. 3442654, No. 3
No. 475174, No. 3545974, OLS No. 1942665, British Patent No. 107731
No. 7, No. 11984 and No. 50, etc., "Synthesis of surfactants and their applications" by Ryohei Oda et al. (Maki Shoten 1964 edition): "Surface Active" by A. W. Peiri
"Encyclopedia of Surf Science, Inc." (Interscience Publications, Inc., 1958 edition): T. P. Sisley, "Encyclopedia of Surf Science, Inc., Volume 2" (Chemical Publishing Co., Ltd., 1964 edition): "Interfaces It is described in "Handbook of Activators", 6th edition (Sangyo Tosho Co., Ltd., December 20, 1960), etc.

These surfactants may be added alone or in combination.

Although these may be used as antistatic agents, they may sometimes be applied for other purposes, such as dispersion and coating aids.

To form the back layer, the above-mentioned composition is dissolved in an organic solvent and applied as a coating solvent onto a non-magnetic support.

This support is made of polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, plastics such as polycarbonate,
Non-magnetic metals such as Cu and ALZn, glass, magnetism, ceramics such as earthenware, etc. are used.

These non-magnetic supports are in film form and have a thickness of approximately 3 to 100 μm.
The thickness is preferably 5 to 50 μm.

In kneading the above-mentioned components, each component is fed into the mixing machine either all at the same time or one after another.

Various types of kneading machines are used for cross-mixing and dispersion.

For example, two roll mill, three roll mill, ball mill,
Pebble Mill, Thoron Mill, Sant Kleinder, Sze
gvar i attritor, high speed impeller disperser, high speed stone mill, high speed impact mill, disperser, kneader-1 high speed mixer, homogenizer, ultrasonic disperser, etc.

The technology related to crosstalk dispersion is written by T. C. PATTON.
Pa1nt Flow and Pigment D
John Wispersion” (1964, John Wi.
published by Ley & 5ons).

It is also described in US Pat. No. 2,581,414 and US Pat. No. 2,855,156.

Methods for applying the above-mentioned back layer onto the support include air doctor coating, grade coating, air knife coating,
squeeze coat, impregnation coat, reverse roll coat,
Transfer roll coat, gravure coat, kiss coat, cast coat, spray coat, etc. are available.
Other methods are also possible, and detailed explanations of these can be found in "Coating Engineering" published by Shokusen Shoten, pages 253 to 277 (
(Published on March 20, 1972).

Organic solvents used during coating include ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohols such as methanol, ethanol, gropanol, and butanol; methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, and acetic acid. Ester systems such as glycol heptanoethyl ether; ether, glycol dimethyl ether, glycol monoethyl ether,
Glycol ethers such as dioxane; Tars (aromatic hydrocarbons) such as benzene, toluene, and xylene; Chlorinated hydrocarbons such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, ethylene chlorohydrin, dichlorobenzene, etc. can be used.

The magnetic layer for manufacturing the magnetic recording body of the present invention is provided by a conventional method.

The present invention will be explained in more detail below using 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 invention should not be limited to the examples below.

In addition, in the following examples, all parts indicate parts by weight.

Example 1 Carbon black [Asahi Carbon #35 75 parts (
Asahi Carbon Co., Ltd. (split product name) Niantimony trioxide (Sb203, average particle size 25 parts diameter 0.4μ) Polyester resin 100 parts Methylene chloride/ethylene chloride (1:1 400 parts mixed solvent) The above composition was milled in a ball mill. The mixture was thoroughly mixed and dispersed and applied as a magnetic recording back layer to the back side of a wide video tape to a dry thickness of 2.8 μm.

The videotape web used was a wide web of broadcasting videotape V-700 manufactured by Fuji Film Corporation.

After drying, it was slit into a width of 5.08 (177L (1/2)) to obtain sample #1.

A scratch resistance test was conducted on this sample #1.

This test method involves passing a magnetic tape over a video tape recorder and running the tape.
A bronze pole of rL is pressed against the specimen to intentionally create scratches, and the even number of scratches over a length of 50 m is counted and used as a measurement value.

The result was 1. Since this test is a relative measurement, the above operations must be performed under identical conditions.

Therefore, all samples obtained in the following examples were tested under the same conditions.

All results are summarized in Table 1.

Example 2 In place of 25 parts of diantimony trioxide used in Example 1, 20 parts of diantimony trioxide and antimony oxybromide (III) (5bOBr, average particle size 0) were used.
．． A magnetic tape was prepared by mixing 10 parts of 7μ), and this tape was designated as sample #2.

The measured value of the scratch test similar to Example 1 was 2.

Example 3 Niantimony trioxide (Sb203, average 120 parts particle size 0.4μ) Vinyl chloride-vinyl acetate-vinylalcohol copolymer (copolymerization ratio 86:12:2) Hohigenol L-12 (Kako Atlas 2 Department Co., Ltd.
500 parts of methyl ethyl ketone The above composition was thoroughly kneaded in a ball mill.

Next, 10 parts of a polyisocyanate compound (Desmodur L-75 manufactured by Bayer) was added and further stirred.
A magnetic recording back layer was coated on the back side of a music magnetic tape to a dry thickness of 3 μm.

The tape thus obtained, sample #3, had a bright white back surface and had excellent marking properties.

Since this tape did not contain carbon black, a scratch test was not performed.

Example 4 Instead of 25 parts of diantimony trioxide used in Example 1, 20 parts of diantimony trioxide, 10 parts of aluminum oxyhydroxide (average particle size 0.1μ), 9 antimony oxychloride (■) (Sb403C12, Average particle size 0.5μ
) A magnetic tape was manufactured using a mixture of 10 parts of the sample #4.

The measured value of the scratch test was O.

Comparative Example l A magnetic tape was manufactured using 100 parts of carbon black instead of 75 parts of carbon black used in Example 1, and without adding all of the diantimony trioxide used in Example 1, and sample #5 And so.

The measured value of the scratch test was 18.

The reflective optical density of each sample back layer was then measured using a Breturf compact densitometer.

The results are shown in Table 1 along with the measured values of the number of scratches.

As is clear from these results, the back layer of the magnetic recording medium of the present invention is brighter than the back layer made of carbon black alone, making it easier to visually see markings and writing with a pen.

It also has excellent wear resistance.

I investigated the antistatic property and found that #1, #2, #4, #
No. 5 was good, and no large differences were observed between the samples.

Comparative Example 2 A magnetic tape was produced in the same manner as in Example 1 using 25 parts of zinc oxide (average particle size 0.4μ) instead of 25 parts of diantimony trioxide used in Example 1, and Sample #6 was prepared.
And so.

In addition, a magnetic tape was manufactured in the same manner as in Example 1, using 25 parts of titanium oxide (TiO2, rutile type, average particle size 0.4μ) instead of 25 parts of antimony trioxide used in Example 1. , sample #7.

The reflective optical density of each sample back layer was then measured using a Breturf compact densitometer.

The results are shown in Table 2 together with the measured values of the number of scratches.

It can be seen that diantimony trioxide has excellent optical density and scratch resistance.

Example 5 It is clear from the following experiments that the back layer (for magnetic recording media) containing fine powder of antimony oxide and antimony oxyhalide according to the present invention reduces the risk of fire during the paint manufacturing process. It became.

The back layer paints used for samples #1 to #7 were poured into an evaporating dish and dried in an air dryer.

After drying, the combustibility was examined by bringing a small flame close to the dried solidified paint, and the results were as shown in Table 3.

It can be seen that the back layer formulation according to the invention is less likely to ignite.

The above flammability tendency also appears in magnetic recording media (with a back layer).

That is, only #1 to #4 according to the present invention had self-extinguishing properties when a flame was brought close to the magnetic recording medium (1/2 inch width 25 CrrL).

Claims (1)

[Claims] 1. A magnetic recording material having a magnetic recording layer on one side of a film-like support and a back layer dispersed in a powdery binder on the other side, in which antimony oxide and antimony oxyhalide are added to the back layer. A magnetic recording medium containing at least one type of fine powder.