JPS6055515A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain appropriate slip characteristics as well as highly driving stability of a back-coat layer and at the same time to eliminate bleeding-out phenomena, by providing at least one layer containing manasseite on a supporter set oppositely to at least one magnetic layer. CONSTITUTION:At least one layer containing manasseite is provided on a supporter set oppositely to at least one magnetic layer. The grain size of manasseite is preferably set at 1-0.002mum and more preferably at 0.5-0.002mum. The amount of manasseite is set at 5-200pts.wt. to 100pts.wt. binder and preferably at 10-120pts.wt. The thickness of a back-coat layer is set at 0.1-2mum and more preferably at 0.3-0.8mum respectively.

Description

Detailed Description of the Invention (Al Industrial Field of Application) The present invention relates to the improvement of magnetic recording media having a back coat layer, and in particular to improving the slipperiness of the back coat layer, eliminating tape folds, edge dust, etc., and improving running performance. It has excellent performance and running stability, and has no bleed-out (
This relates to a magnetic recording medium that does not cause brasd out.
The magnetic paint obtained by dispersion is applied onto a support such as a polyester film and dried to form a magnetic layer, or a magnetic material is vapor-deposited, sputtered, plated, etc. onto the support. to form a magnetic layer.

This magnetic recording medium is widely used in the fields of audio, video, computers, etc. as magnetic tape, magnetic disk, magnetic sheet, floppy disk, etc. In magnetic recording media for audio and video, the surface of the magnetic layer is finished to be smooth in order to improve sensitivity (%, output in high frequency range). In addition, audio tapes with thinner tapes have been commercialized because of the need for long-term recording and playback.

Videotape SO also depends on the spread of video.1. There has been a growing demand for the production of thin, thin-walled tapes that can be used for long periods of recording and playback.

A magnetic recording medium with a thin wall and a smooth surface has a large contact area between the layers of the recording medium or between the recording medium and another object, such as a guide rod, and the 1# friction resistance increases, resulting in poor running performance. Becomes unstable.

In addition, after a recording medium such as a magnetic tape has been wound many times, both end surfaces of the tape wrapping body are not aligned neatly.
It is easy to cause so-called disordered winding. This causes deformation and bending of the edge portions of the magnetic tape, which can cause 4" screen distortion and distortion in the output and video tapes.

Based on the tape thinning ζ, the accompanying decrease in mechanical strength of the tape, and the smoothing of the magnetic surface (excluding running instability,
Usually, a method is adopted in which a back coat layer is provided on the surface of the support opposite to the surface on which the magnetic layer is formed71. ing.

The back coat layer is disclosed in, for example, Japanese Unexamined Patent Publication No. 52-102004. I! As described in fiW, a paint containing powders of carbon black, kaolin, silicon dioxide, titanium oxide, etc. bound together with a binder is applied to the surface of the support opposite to the surface on which the magnetic layer is formed. However, the surface of the layer is roughened by forming many irregularities.

However, when this kind of roughened back coat layer is wound with magnetic tape, its uneven state is transferred to the surface of the magnetic layer, impairing the smoothness of the surface of the magnetic layer, and improving electromagnetic characteristics and chroma S. /N and video S/N decrease. In addition, in this type of magnetic recording medium, if the unevenness of the surface of the tape coating layer is not appropriate, shinching ("loosening of the tape" that occurs when the tape stops rapidly) occurs.

As a means of eliminating the above-mentioned defect that the rough surface state (uneven state) of the bank coat layer is transferred to the magnetic layer surface and increasing the slipperiness of the tape (that is, reducing the coefficient of friction), for example, eD JP-A-58- Publication No. 37840
It is proposed that the coating layer contains fatty acids (or fatty acid esters) and inders as lubricants along with inorganic powder.

However, with this method, the fatty acids and fatty acid esters contained in the layer may become sticky if the lubricant addition or surrounding environmental conditions change.1. In addition, the specification of JP-A-1'17-111828 has the disadvantage that these act as plasticizers, causing interlayer adhesion, decreasing film strength, or bleeding out onto the surface of the back coat layer. By selecting black carbon with appropriate particle size and BUILT value (specific surface area) and mixing it with the binder at an appropriate ratio, the antistatic effect of the bank coat layer, interlayer adhesion, and magnetic layer properties can be improved. This shows that it is possible to prevent the transfer of

Of course, by using this zero method, the above-mentioned drawbacks can be overcome by selecting the particle size of the non-magnetic powder and the blending ratio of the non-magnetic powder to the binder within an appropriate range. Can be removed. However, the coefficient of friction, etc. was still quite high, the running properties were not sufficient, and the advantage of providing the bank coat layer was not necessarily sufficient.

In view of the above-mentioned circumstances, the inventors of the present invention have repeatedly conducted various experiments regarding the bank coat layer of magnetic recording media, and have found that the chemical formula is as follows: It is a crystal that belongs to the hexagonal system, and has a hardness of about 2 and is comparable to talc (
It is harder than alumina oxide (hardness = 1), softer than alumina oxide (hardness = 9) and silicon oxide (hardness = 7), has excellent slipperiness, has good dispersibility in binders, and does not become sticky. It was discovered that it does not become plasticized or bleed out.

The present invention has been achieved based on the above-mentioned findings regarding manaceite.

[c] Purpose of the Invention The present invention provides a magnetic recording medium having a specific layer on a support opposite to the magnetic layer, in which the specific layer has appropriate sliding properties and excellent running properties and running stability. and to provide a magnetic recording medium that does not cause bleed-out in the specific layer. In this magnetic recording medium, at least one layer containing manaceite (hereinafter referred to as the layer of the present invention) is provided on the support opposite to at least one of the magnetic layers.
This is achieved by a magnetic recording medium having layers.

In the magnetic recording medium according to the present invention, manaseite that can be used in the layer of the present invention has the chemical formula, for example, Mg5A/? It is a crystal with a composition expressed by z(OH)tacOa・4H20, belongs to the hexagonal system, and is usually plate-shaped,
It is produced in fibrous and lumpy forms. Moreover, the hardness is about 2.

The above manaceite has a particle size of 1 μm to 0.002 μm.
0.5 μm is particularly preferable.
It is in the range of ~0.002 μm. Particle size is 1μm
If it exceeds 0, the layer of the present invention containing the particles becomes extremely uneven, the surface of the layer of the present invention becomes rough, and the tape performance is deteriorated. A back coat layer containing manaceite with a diameter of less than 0.002 μm is not roughened and has almost no effect of containing manaceite.

The amount of manaceite added to the layer of the present invention is from 5 parts by weight to 200 parts by weight, preferably from 10 parts by weight to 120,120 parts by weight, based on 100 parts by weight of the binder. If the amount added is less than 5 parts by weight relative to the VL quantity of binder 100, the slipperiness of the bank coat layer cannot be obtained, and if it exceeds 200 parts by weight, the binding force of the binder will not work sufficiently, and the present invention layer becomes easy to peel off. The binders that can be used will be described later.

In the magnetic recording medium 1 according to the present invention, manaceite contained in the layer of the present invention may be contained alone in the binder, or may be contained in combination with other non-magnetic powder.

The layer of the present invention is, for example, a back coat layer, and may be provided before the magnetic layer is provided on the support, or may be provided after the magnetic layer is provided. It may also be provided after surface treatment. Further, the magnetic I- and back coat layers may be provided simultaneously on the upper and lower surfaces of the support.

A back coat layer is provided on the support before the magnetic layer,
If the am layer fR is applied on the side of the support opposite to the back coat layer after it is sufficiently cured, troubles between the bank coat layer and the magnetic layer (eg, sticking, etc.) will be reduced. On the other hand,
A method in which a magnetic layer is provided on a support and then a back coat layer is applied to the surface of the support opposite to the magnetic layer makes it difficult for the surface roughness of the back coat layer to be transferred to the magnetic layer. The thickness of the back coat layer is
The range is preferably from 0.14 m to 2 μm, and particularly preferably from 0.3 μm to 0.8 μm.

If the thickness is less than 0.1 μm, the bank coat layer will not have sufficient surface roughness and runnability cannot be improved. However, since the amount of manaceite added cannot be made sufficient,
The slipperiness is not good. Furthermore, if the thickness exceeds 2 μm, in the case of a cassette in which a fixed length of tape is packed into a fixed volume cassette, the total thickness of the tape is severely limited, and the thickness of the magnetic layer must be drastically reduced. For example, in the case of video tapes, the audio sensitivity is greatly reduced. Non-magnetic powders that can be used in combination with manaceite according to the present invention include, for example, silicon oxide, titanium oxide, aluminum oxide, chromium oxide, calcium carbonate, and Zinc, α-Fe
203, talc, kaolin, and carbide can be used in combination of one or several selected from among 8- silicon, calcium sulfate, silicon nitride, zinc fluoride, molybdenum disulfide, and the like.

The layer of the present invention includes at least the manaceite mixed alone or together with the nonmagnetic powder and binder in a solvent.
After dispersing and preparing a paint, the resulting paint is applied to the surface of the support opposite to the surface on which the magnetic layer is formed and dried. In a magnetic recording medium 10 provided with at least one magnetic layer 2 on a body, at least Ll- of the layer 3 of the present invention is disposed on the support opposite to at least one of the magnetic layers 2. As shown in FIGS. 1, 3 and 4, the layer 3 of the present invention may be on one side.
(The layer 3 of the present invention in Figures 1 and 3 is in the form of a bank coat layer, and the layer 3 of the present invention in Figure 4 is in the form of an overcoat layer). may be double-sided (layer 3 of the present invention is in the form of an overcoat layer).

The magnetic layer can be made by, for example, mixing and dispersing magnetic powder in a solvent with a binder to form a magnetic paint, and the obtained magnetic paint is
A magnetic layer (coating type magnetic layer) is formed by coating on a support. Alternatively, a magnetic layer can be formed by depositing, sputtering, plating, or the like a magnetic material on the support.

Magnetic materials that can be used in the magnetic layer of the magnetic recording medium according to the present invention include r-F@gos, Fe2O2, co-containing -
Oxide magnetic materials such as Fe20B, Co-containing Fe 304, CrO2, Fe-A/gold alloy Fa-kl-P alloy, Fe-Ni-Co alloy, Fe-Mn-Zn alloy, F
e-Ni-Zn alloy, Fe-Co-Ni-Cr alloy, F
Examples include metal magnetic materials such as e-Co-N1-P alloy, Co-Ni alloy, and Co-P alloy.

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

Regarding the manufacturing method of magnetic paint, Japanese Patent Publication No. 35-15, No. 3
No. 9-26794, No. 43-186, No. 47-280
No. 43, No. 47-28045, No. 47-28046, No. 47-28048, No. 47-31445, No. 4
No. 8-11162, No. 48-21331, No. 48-3
Specification of Publication No. 3683, West German Published Patent Application No. 206065
I! Please refer to the details of the specification of item i, etc.^11

Examples of binders that can be used in the layer of the present invention and the paint-on magnetic layer include thermoplastic resins, thermosetting resins, reactive resins, electron beam curable resins, and mixtures thereof.

As a thermoplastic resin, one having a softening temperature of 150"0 or less, an average molecular weight of io, ooo to 200,000, and a degree of polymerization of about 200 to 2,000, such as vinyl chloride-
Vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, nysder acrylate-acrylonitrile copolymer, acrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-vinylidene chloride copolymer Polymer, methacrylic acid ester-ethylene copolymer, urethane elastomer, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer,
Acrylonitrile-butadiene copolymer, polyamide resin, polyvinyl butyral, cellulose 94=11 monolithic (cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose, etc.), styrene-butadiene copolymer, polyester resin , chlorovinyl ether-acrylic acid ester copolymer, amino resin, various synthetic rubber-based thermoplastic resins, and mixtures thereof. These resins are disclosed in Japanese Patent Publication No. 37-6877,
No. 39-12528, No. 39-19282, No. 40
-5349, 40-20907, 41-946
No. 3, No. 41-14059, No. 41-16985,
No. 42-6428, No. 42-11621, No. 43-
No. 4623, No. 43-15206, No. 44-2889
No. 44-17947, No. 44-18232, No. 45-14020, No. 45-14500, No. 47-
No. 18573, No. 47-22063, No. 47-220
No. 64, No. 47-22068, No. 47-22069, No. 47-22070, No. 48-27886, U.S. Patent No. 3, 144.

No. 352, Specification No. 3,419,420, No. 3
, 499.

No. 789 and No. 3,713,887.

The thermosetting resin or reactive m-resin may have a molecular weight of 50,000 to 200,000 in the coating liquid state, and after coating and drying, the molecular weight becomes infinite due to reactions such as condensation and addition. There may be.

Also, among these resins, those that do not soften or melt before the resin is thermally decomposed are preferred.Specifically,
Examples include phenolic resins, epoxy resins, polyurethane curable resins, urea resins, styrene resins, alkyd resins, silicone resins, acrylic reaction resins, mixtures of polymeric polyester resins and isocyanate prepolymers, methacrylate copolymers and diisocyanate prepolymers. These include mixtures of polymers, mixtures of polyester polyols and polyisocyanates, urea formaldehyde resins, mixtures of low molecular weight glycols/high molecular weight diols/triphenylmethane triincyanate, boriaone resins, and mixtures thereof.

Kowara's resin is published in Tokuko No. 39-8303 and No. 40-9.
No. 779, No. 41-7192, No. 41-8016,
No. 41-14275, No. 42-18179, No. 43
-12081, 44-28023, 45-14
No. 501, No. 45-24902, No. 46-13103
No. 47-22067, No. 47-22072, No. 47-22073, No. 47-28045, No. 47-
28048, US Pat. No. 47-28922, US Pat. No. 3.144.353, US Pat. No. 3.320.090
No. 3, 4371510, No. 3,597,2
No. 73, No. 3, No. 781, No. 210, No. 3.78
1.211.

Examples of electron beam irradiation-curable resins include unsaturated prepolymers,
For example, maleic anhydride type, urethane acrylic type, epoxy acrylic type, polyester acrylic type, polyether acrylic type, polyurethane acrylic type, polyamide acrylic type, etc., or as a polyfunctional monomer, ether acrylic type, urethane acrylic type, epoxy acrylic type, etc. Examples include phosphoric acid ester acrylic type, aryl type, and hydrocarbon type.

In the paint-on type magnetic recording medium, the mixing ratio of the magnetic powder and the binder is 5 to 4ooJ[-iu parts, preferably 10 to 200 parts by weight, of the binder to 10 o -+'i parts of the magnetic powder. Mix 1 within the range of . If the amount of the binder mixed is too large, the recording density when used as a magnetic recording medium will decrease, and if it is too small, the strength of the magnetic H will be weakened, resulting in undesirable situations such as decreased durability and dust.

Furthermore, in order to improve the durability of magnetic recording media,
Various hardening agents can be added to the magnetic material. For example, a polyfunctional incyanate or the like can be contained.

Examples of polyfunctional isocyanates that can be used include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, naphthalene diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate, an adduct of diisocyanate and trivalent polyol, or a 5-isocyanate of diisocyanate. Raise it,
Further, 5f consisting of an adduct of 3 moles of tolylene diisocyanate and 1 mole of trimethylolpropane, an adduct of 3 moles of metaxylylene diisocyanate and 1 mole of trimethylolpropane, and an adduct of 3 moles of tolylene diisocyanate and 2 moles of hexamethylene diisocyanate. Examples include the body.

In addition to the magnetic powder, binder, and curing agent, additives such as a dispersant, abrasive, and
An antistatic agent or the like may be added.

Dispersants used include lecithin, phosphate esters, amine compounds, alkyl sulfates, fatty acid amides, higher alcohols, polyethylene oxides, sulfosuccinic acids, sulfosuccinates, known surfactants, and salts thereof. , negative organic groups (e.g. −
Salts of polymeric dispersants with COOHl-PO3H) can be used. These dispersants may be used alone or in combination of two or more. The Kowara dispersant is added in an amount of 1 to 20 parts by weight per 100 parts by weight of the magnetic powder.

Regarding these dispersants, Japanese Patent Publication No. 41-18064,
No. 49-84405, No. 52-70811, No. 57
-16- 1048, publication specification, JP-A-57-33430 specification, U.S. Patent No. 3,587,993, U.S. Patent No. 3
, 470.

021 specification etc. can be referred to.

As a lubricant, silicone oil, carbon black, graphite, molybdenum disulfide, tungsten disulfide,
A fatty acid ester consisting of a monobasic fatty acid having 12 to 16 carbon atoms and a monohydric alcohol having a total number of carbon atoms of 21 to 23 carbon atoms can be used. These lubricants are 0% against magnetic powder ioo
．． It is added in an amount of 2 to 20 parts by weight. Regarding Koi 1 and others, Tokuko No. 43-23889, No. 43-81543
Publication specification, US fFM No. 3,470.021, US fFM No. 3,492,235, US fFM No. 3,497,411,
No. 3,523.086, No. 3, 625, 72
No. 0, No. 3,630,772, No. 3.634.2
No. 53, @3,630,772, No. 3, 634
, No. 253, No. 3,642.539, No. 3.6
Specifications of No. 87,725, IBM Technical Disclosure Plutan Magazine Volume 9, No. 7, Page 779 (December 1966) (IBM Technic
al Disclosure Bulletin vo
l, 9.47 r Page779 (196L De
cember): Electronics Magazine No. 12,
Page 380 (1961) (ELEKTRONrK, 12゜page 380.1961) etc.
ing.

Fused alumina, a material commonly used as an abrasive
Silica carbide, chromium oxide, corundum, artificial corundum, artificial diamond, garnet, emery (main ingredients: corundum and magnetite), etc. are used. These abrasives have an average particle size of 0.05 to 5 .mu.m, preferably 0.05 to 2 .mu.m. These abrasives are added in an amount of 0.5 to 20 parts by weight per 100 parts by weight of the magnetic powder. These abrasives are described in JP-A-49-115510 and U.S. Patent No. 3.0.
No. 07,807, No. 3,041,196, No. 3,
No. 687,725, British Patent No. 1,145,349 Department of Mining, West German Patent (DT-PS) No. 853,211 0 If necessary, as an antistatic agent, graphite, carbon Dielectric powders such as black, tin oxide-antimony oxide compounds, tin oxide-titanium oxide-antimony oxide compounds, and carbon black graft polymers; Natural surfactants such as saponin; alkylene oxide-based, glycerin-based, glycidol-based, etc. Anionic surfactant:
Cationic surfactants such as higher alkylamines, @quaternary pyridine, other heterocycles, phosphoniums or sulfoniums: Contains acidic groups such as carboxylic acid, sulfonic acid, phosphoric acid, sulfate ester groups, phosphate ester groups, etc. Anionic surfactants Ampholytic surfactants such as diamino acids, aminosulfonic acids, sulfuric acid or phosphoric acid esters of amino alcohols, and the like are used.

These surfactants that can be used as antistatic agents include U.S. Patent No. 2.271,623, U.S. Pat.
No. 24, No. 2,676.975, No. 2.691,
No. 566, No. 2.727.860, No. 2.730
．． No. 498, No. 2゜742.379, No. 2,73
No. 9,891, No. 3, 068.

No. 101, No. 3,158.484, No. 3.201
, No. 253, No. 3,210,191, No. 3, 2
94, No. 540, No. 3,415.649, No. 3
．． 441.413, 3.442.654, 3,475,174, 3゜545.974,
West German Patent Publication No. 1,942,655, British Patent No. 1
．． In addition to specifications such as No. 077.317 and No. 1.198.450, Ryohei Oda et al. [Synthesis of surfactants and their applications] (Maki Shoten 1964 edition); Active Agents” (Interscience Publications Inc. 19)
1958 edition): T, P.

"Encyclopedia of Surface Active Agents Volume 2" by Sisley (Chemical Published Company 1964 edition) = "Surfactant Handbook" 6th edition (Sangyo Tosho Co., Ltd. December 2, 1964)
0 days) etc.

These surfactants may be added alone or in combination. Although these are used as antistatic agents, they may sometimes also be applied for other purposes, such as dispersion, improving magnetic properties, improving lubricity, and as coating aids. The use of these lubricants and antistatic agents can reduce the field 8 and force 5, and improve the properties of the magnetic layer.

Solvents for magnetic paint or solvents used when applying magnetic paint include acetone, methyl ethyl ketone (MEK),
Ketones such as methyl isobutyl ketone (M113K) and cyclohexanone; Alcohols such as methanol, ethanol, propatool, butanol; and esters such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, propyl acetate, and ethylene glycol monoacetate! Diethylene glycol dimethyl ether, 2-ethoxyer I/
8) Aromatic hydrocarbons 2Methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, dichlorobenzene and other halogenated carbonaceous water, etc. can be used.

In addition, when mixing the magnetic paint components, the magnetic powder and other magnetic paint components are fed into a mixer all at the same time or individually one after another. For example, first, the magnetic powder is mixed into a solution containing a dispersant. The mixture is added and kneaded for a predetermined period of time, and then the remaining components are added and mixing is continued to form a magnetic coating material.0 For cross-mixing and dispersion, the cross-mixing machine of each item (2) is used.

For example, two roll mill, three roll mill, ball mill, pebble mill, sand grinder, Sjegvar
These include i-Attritor, high-speed impeller dispersion machine, high-speed stone mill, high-speed impact mill, Disper Kneader-1 high-speed mixer, homogenizer, and ultra-single-wave dispersion machine.

Technologies related to crosstalk and dispersion are described in Chi O Paratong's ``
Paint Flow and Pigment Dispersion (1964, published by John Wiley and Nun)
J T, O, PATTON (PaintFlowa
ndPlgmentl) ispernion (196
4, John Wllley and Son)) and U.S. Patent No. 2,581,414.
No. 2,855,156.

In addition, as materials for the support, polyesters such as polyethylene/ntele 7-talate and polyethylene-2,6-naphthalate, polyolefins such as polypropylene,
Cellulose conductors such as cellulose triacetate and cellulose diacetate, plastics such as polycarbonate, Cu, AI! , metals such as Zn, glass, and ceramics such as so-called new ceramics (for example, boron nitride, silicon carbide), etc. are used.

Support forms include tape, sheet, card, disk,
Any material such as a drum may be used, and various materials are selected as necessary depending on the form.

The thickness of these supports is approximately 3 mm in the case of tape or sheet form.
- about 100 μm, 5 to 50 μm for wild monkeys, and 30 μm −l in the case of disks and cards.

It is about the size of a basket, and if it is drum-shaped, it is cylindrical, and its shape is determined depending on the recorder used.

In addition, methods for applying the layer of the present invention or the self-magnetic paint onto the support include gravure roll coating, Mayer bar coating, doctor blade coating, reverse roll coating, dip coating, and air knife coating. Methods such as , calendar coating, squeeze coating, kiss coating, fantine coating, etc. can be used, and other methods are also possible. Specific explanations of these methods are given in "Coating Engineering" (March 1970, Asakura) Published by Caodian, 2nd edition
(pages 58 onwards) and ``Plastic Film - Processing and Its Applications'' (published by Gihodo in 1971).
ing.

The magnetic layer coated on the support by such a method is, if necessary, subjected to a treatment for orienting the magnetic substance in the layer, and then the coated magnetic layer is dried. Further, a magnetic recording medium is manufactured by performing surface smoothing processing and cutting into a desired shape if necessary.

The orientation direction of the magnetic material used in the magnetic recording medium of the present invention is determined according to its intended use.

In addition, in a magnetic recording medium having a magnetic layer formed by vapor deposition, sputtering, plating, etc., the layer of the present invention may be used in combination with a known overcoat layer, Barafco-25-, or Heheto layer. . FIG. 3 shows an example in which a known overcoat layer 4 is also used.

[e) Examples Hereinafter, specific contents of the present invention will be explained with reference to Examples and Comparative Examples.

In the Examples and Comparative Examples, the description "RF trace" refers to "parts by weight."

Examples 1 to 4 ■ Formation of the layer of the present invention: Each composition component (not shown in column 1 of Table 1 below) was added to column 2 of Table 1 below. @3. Non-Mi powder-containing compositions-1 and II blended at the mixing ratios shown in the fourth and fifth sections.

■ and 1v were placed in a ball mill and stirred and mixed for 30 hours. The composition was then filtered through a filter with an average pore size of 1 μm, and 5 parts of polyfunctional isocyanate (curing agent) were added and mixed uniformly to form 4 types of Paint (11, (Ill,
alD: Jd Yopi (IV) 'P-H Construction L 7. :.

26- Table-1 Obtained letter paint (ll, (Il), (til + Oyohi (Ivl'E soresore, four sheets of 14 μm separately prepared)
The layer of the present invention was formed by coating and drying on a thick polyester film.

■ Formation of magnetic layer; Next, each composition component shown in column 1 of Table 2 below was added to
The magnetic powder-containing composition blended at the mixing ratio shown in the second and third columns was charged into a ball mill, mixed and dispersed for 72 hours, filtered through a 1 μm mesh filter, and further mixed with 5 parts of polyfunctional oil-based incyanate. was added and applied to a thickness of 5 μm on the surface of each of the four polyester films described in II on the side opposite to the layer installation area marked with (■), and dried to form a magnetic layer.

Margin below 27- Table 2 28- The magnetic layer surface of each film thus obtained was supercalendered and then cut into 12.65 m widths to produce video tapes.For each of the video tapes obtained,
According to the difference in the mixing ratio for each composition component shown in Table-1 and Table-2, n was changed to Example tape (z).
, (2) + Comparative examples 1 to (3) and (4)
4. Formation of bank coat layer: First, each of the composition components shown in the column No. 6 of the above-mentioned coating-1 was added to No. 6. 7th. The non-magnetic powder-containing compositions - Comparison ■, - Comparison ■, - Comparison ■ and Comparison ■, blended at the mixing ratios shown in columns 8 and 9, were charged into a ball mill, stirred and mixed for 30 hours, and then the compositions were mixed. Filter through a mesh filter with an average pore size of 1 μm, and remove polyfunctional isocyanate (curing agent).
5 parts of were added and mixed uniformly to prepare four types of back coat paints.

The obtained back coat paint was applied onto four 14 μm thick polyester films prepared separately.
It was dried to form a back coat layer.

■ Formation of magnetic layer: Next, the above! A magnetic powder-containing composition prepared by mixing each composition component shown in the first column of -2 at the mixing ratio shown in the second column and third column, respectively, was charged into a ball mill, mixed and dispersed for 72 hours, and then a 1 μm mesh was prepared. 5 parts of a polyfunctional isocyanate was added thereto, and the mixture was coated to a thickness of 5 μm on the opposite side of the four polyester films from which the back coat layer was formed, and dried to form a magnetic layer.

The magnetic layer surface of each of the films thus obtained was subjected to supercalender treatment, and then slit to a width of 12.65mm to 12.65mm to produce a videotape. For each videotape obtained,
Comparative Example Tape (4) and (21
, (3) and (4).

In addition, in Clothing-1 and Table-2, the partially hydrolyzed vinyl chloride-vinyl acetate copolymer is, for example, rVAGHJ manufactured by Union Carbide, and the polyurethane in Table-2 is, for example, manufactured by Nippon Polyurethane Co., Ltd. Polyurethane rN2304J manufactured by

Example tapes (11 to (4)) and comparative example tapes (sl
The tape performances of (4) to (4) were evaluated based on chroma S/N, skew value, jitter value, friction coefficient, average surface roughness, and maximum surface roughness.

The results are shown in Table-3. However, ■) Chroma S/N: Chroma signal (3,58MHz) >50.7 L 4
After recording with the brightness signal set to Vp-p,
, extract only the chroma signal, and calculate its effective value (S
) and the noise level ■ when the chroma signal is removed. However, in Table 3, the values are expressed as relative values when the value of Comparative Example Tape (2) is % OdB.

2) Skew value: Record the color par signal on tape, and use a video deck to record the color par signal on tape.
Fast forward and rewind 100 times at room temperature, measure the image distortion at the switching point on the monitor screen, and calculate β(
6).

3) Jitter value: This value represents the "fluctuation" of the reproduced signal in the time direction, and was measured using a jitter meter.

4) Friction coefficient: The friction coefficient between the back coat layer and the chromium was measured using a 4-tone chrome bottle and was expressed as a value.

5) Drop act: Measured using a dropout counter, the number of -20 dB output losses of 15μ (transfer) is more than iooo. It was set as a step needle price.

Table 3 From the results in Table 3, it can be seen that the video tape having a back coat layer containing manaceite according to the present invention has a lower chroma S than the video tape having a back coat layer containing alumina powder or titanium oxide. is also much higher,
This shows that the running performance and running stability are excellent.

Regarding the skew value and jitter value, in the case of a videotape having a layer containing manaceite according to the present invention, a videotape having a back coat layer containing alumina or titanium oxide with the same particle size (0.5 μ →
This value is smaller than that of Comparative Example Tapes (3) and (4)), indicating that there is no uneven running and excellent running stability.

[f] Effects of the Invention As is clear from the above results, the magnetic recording medium according to the present invention has a layer containing: Even if it is not, the slipperiness of the magnetic recording medium is superior.

2) Probably because the manasseite used is a solid,
For example, it does not bleed out onto the surface of the back coat layer or cause interlayer adhesion between the back coat layer and the magnetic layer.

3) The conventional method of roughening the back coat layer by adding non-magnetic powder such as alumina or titanium oxide has no effect unless the surface is considerably roughened. 1. However, the magnetic recording medium having a layer containing manaceite according to the present invention relies on the lubricity and appropriate roughness of manasseite itself, The layer of the present invention can be maintained relatively smooth without impairing the smoothness of the surface of the magnetic layer.

4) In addition, by using Manaserite in combination with carbon black, etc., it is possible to eliminate volumetric defects (for example, dropouts) caused by charging of magnetic tape, thereby obtaining a better magnetic recording medium. can do 0

[Brief explanation of the drawing]

FIG. 1, FIG. 2, FIG. 3, and FIG. 4 are enlarged sectional views each showing an embodiment of the magnetic recording medium of the present invention. ■ ・・・・・・・・・Support 2 ・・・・・・・・・a performance 3 ・・・・・・Layer 4 of the present invention ・・・・・・・・・Overcoat Layer lO...
...Magnetic recording media procedure amendment 7F (voluntary) +1/+ fn October 14, 1958 1, Case indication 1983 Patent Application No. 183088u Relationship with case Patent applicant address Tokyo 1-26-2 Nishi-Shinjuku, Shinjuku-ku Name (
Name) (127) Konishiroku Photo Industry Co., Ltd. 6. Number of inventions increased by amendment tx t. 7. Column 8 of "Detailed Description of the Invention" of the specification to be amended, contents of the amendment as shown in the attached sheet. (1) Page 7, line 13 of the specification: ``...transcribe...''
・" has been changed to ``It may be easy to transfer...''. (2) The statement "Almost never." on page 7, line 16 of the specification cylinder is changed to "In some cases." (3) On page 9, line 10 of the specification tube, ``River slipping properties are poor.'' The statement in j is changed to ``...Sliding properties may be insufficient...''. (4) On page 9, line 15 of the specification tube, the statement "will be significantly reduced" will be changed to "...may be reduced". Above 107-

Claims (1)

[Claims] A magnetic recording medium having at least one magnetic layer on a support, characterized in that it has at least five layers containing manaceite on the support opposite to at least one of the magnetic layers. Medium.