JPS60246021A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having improved lubricity, running property, durability, etc. by incorporating a functional comb-line polymer having >=1 kind of polar functional groups such as F, Si, OH and NH2 at the side chain into >=1 layer of a magnetic layer, protective layer and back coat layer. CONSTITUTION:The paint dispersed therein with magnetic powder contg. the comb-line polymer having the side chain of the length (about 1,000-10,000mol. wt.) approximately equal to the length (mol.wt.) of the principal chain and the polymer having the polar functional groups such as F, Si, OH, NH2 and NCO at the side chain together with other resin for the binder is coated on a substrate and is cured to form the magnetic layer. The protective layer contg. said polymer without contg. the magnetic powder is otherwise provided on the magnetic layer. The back coat layer contg. said polymer is otherwise provided on the rear of the substrate on which the magnetic layer is formed. The magnetic recording medium with which the lubricity is maintained for a long period and which does not stain a magnetic head, etc. owing to bleeding of a lubricant and has excellent durability is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to magnetic recording media, and particularly to magnetic recording media having a coating layer such as a magnetic layer, mainly for improving the surface 1111 lubricity and adhesion of the coating layer. The present invention relates to magnetic recording media.

BACKGROUND OF THE INVENTION Magnetic recording media such as magnetic tapes, magnetic sheets, and magnetic disks are widely used in the audio field for recording sound, the video field for recording images, and the computer field. The magnetic recording media used in these various fields include coated type, in which a magnetic layer is formed on the support by applying a magnetic coating mainly consisting of magnetic powder, binder resin, and solvent onto the support and drying it. things are widely used. In such magnetic recording media, electromagnetic conversion is performed when the magnetic layer is rubbed and scanned by a magnetic head during recording and reproduction, so it is necessary that the magnetic layer has good magnetic properties or electromagnetic conversion properties. be. For this purpose, the spacing loss between the magnetic head and the magnetic layer must be small, and when a magnetic tape is used, for example, it must be able to run smoothly relative to the magnetic head and the guide bin that guides the tape. Stable running properties are required, such that the edges of the winding form are aligned in one plane and the sliding condition with the head does not change when the winding is repeated and used. Additionally, as the magnetic layer is rubbed, it is likely to cause wear such as magnetic powder falling off, and if this happens, the playback output will decrease, and output fluctuations, dropouts, and noise may occur. As an increase etc. occurs,
The magnetic layer is required to have mechanical properties that can withstand rubbing against the head.

In order to achieve good running properties of a magnetic recording medium, it is necessary to improve the surface lubricity of the magnetic layer.
In order to have good mechanical properties that prevent the magnetic powder from falling off, etc., the magnetic layer must have good adhesive properties. These properties are not only required when a magnetic recording medium reproduces sound or images, but also when the magnetic recording medium is rotated at high speed or compared to normal playback operations such as fast forward, rewind, and fast forward playback. It must also be able to withstand harsh conditions.

In particular, trends in magnetic recording technology in recent years include, for example, in audio tapes, the use of compact cassettes is transitioning to the use of microcassettes, and in the video field, the current VIIS and β systems have been replaced by 8mm video, With the shift to electronic cameras, the trend is to make them even smaller and more dense.
For example, when it comes to magnetic tape, its path is becoming more complex and there are many opportunities for it to come into contact with guide poles, guide rollers, etc., so it is often rubbed, and further improvements in its running properties, wear resistance, and other properties are desired. ing.

Among these properties, in order to improve lubricity, it has been carried out to improve the dispersibility of magnetic powder and to include a lubricant in the magnetic layer. Further, a bank coat layer is provided on the back surface of the magnetic tape, and this hack coat layer also contains a lubricant to impart lubricity to the surface thereof.

For example, JP-A-58-23325 discloses an example in which the lubricity of the magnetic layer is improved using a fat-like ester or silicone oil. However, when these fatty acid esters and silicone oil are added to the magnetic layer, these materials do not ooze out to the surface of the magnetic layer over time, causing a so-called blooming phenomenon. Furthermore, a magnetic layer formed from a magnetic paint containing silicone oil tends to have uneven coating, making the coating film non-uniform.

The reason for this is that when these substances are mixed with magnetic powders and binders used in the magnetic layer, such as polyurethane, vinyl chloride-vinyl acetate copolymer resins, etc., the resins are relatively non-polar; Since magnetic powder has a high polarity, it is not compatible with either of these substances with significantly different polarities, and is considered to be easy to separate because its compatibility with these substances is insufficient. If a large amount of lubricant oozes out onto the surface of the magnetic layer in this manner, it not only increases the spacing loss, but also contaminates the magnetic head, and the dirty magnetic head contaminates the magnetic tape having a clean surface. Furthermore, if this lubricant oozes out excessively, the lubricant will adhere to the surface of the magnetic layer in the form of particles or oil, which will actually increase the friction between the tape and the magnetic head when the magnetic tape is scanned by the magnetic head. This results in an increase in running tension, sticking to the head, and an increase in magnetic powder falling off.Furthermore, when the tape is wound, the edges of the tape become uneven, resulting in poor winding appearance. It impairs running performance during use. In addition, as a result of poor compatibility with the binder, uneven coating occurs when applying the magnetic paint, and when this uneven coating occurs, running stability is not achieved and wear resistance is also uneven. will occur. If the lubricity of the magnetic layer is poor, which adversely affects the magnetic layer and reduces running stability, it may impair electromagnetic conversion characteristics such as brightness S/N and squareness ratio, and may cause output fluctuations and dropouts. Improvement was desired.

Furthermore, in order to improve the adhesion of the magnetic layer to the support, an undercoat layer is provided between the support and the magnetic layer, but even with such an undercoat layer, the adhesion remains Not enough.

The above was a case where a lubricant was used for the magnetic layer, but even when the above lubricant is used for the back coat layer, blooming of the lubricant and uneven coating of the coating layer may occur as described above. Yes, the S/N is reduced. Furthermore, the adhesion of the back coat layer to the support is not sufficient when operating magnetic recording media at high speeds as described above.
For example, it may cause partial peeling of the back coat layer, so improvement in this problem is desired.

OBJECTS OF THE INVENTION A first object of the present invention is to provide a magnetic recording medium with good lubricity.

A second object of the present invention is to provide a magnetic recording medium with excellent adhesion between the coating layer and the support.

A third object of the present invention is to provide a magnetic recording medium in which the surface properties of the coating layer do not change over time and the output and S/H do not deteriorate over a long period of time.

Structure of the Invention As a result of extensive research, the present inventor has found that the above object can be effectively achieved by incorporating a functional comb-shaped polymer into the coating layer, leading to the present invention.

Therefore, the magnetic recording medium of the present invention is characterized by having a layer containing a functional comb-shaped polymer containing at least one of a fluorine atom, a silicon atom, and a polar functional group.

The present invention will now be described in more detail.

The functional comb-shaped polymer used in the present invention has a comb-shaped branched chain in the main chain of the polymer, and is characterized by the fact that the molecular weight of the branched chain is large. The molecular weight of this branched chain is, for example, 1,000 to 10,000, and may be approximately equal to the molecular weight of the main chain. This polymer main chain consists of repeating unit bonds of thermoplastic resin, thermosetting resin rings, and polymers commonly used for coatings. Examples include repeating unit bonds in urethane, polyester, epoxy, phenoxy resins, and the like. Further, the branched chain contains a fluorine atom, a silicon atom, a polar functional group, or the like. Examples of the polar functional group include a carboxy group, a hydroxyl group, a sulfonic acid group, an amino group, and salts thereof. In addition to the above, this branched chain also includes relatively nonpolar groups such as polyalkylene groups and aryl groups.

Due to the presence of polar groups as described above in the branched chains, the following characteristics appear when this comb-shaped polymer is included in a coating layer such as a magnetic layer or a back coat layer.

(1) The above-mentioned functional comb-shaped polymer containing fluorine atoms or silicon atoms in its branched chains can improve its surface lubricity by being included in the magnetic layer, hack coat layer, or the like. On the other hand, since the branched chains extend in a comb-like manner from the main chain, they often come into contact with binders, magnetic powders, fillers, etc., and are easily stained and bonded strongly. Therefore, in the coating layer containing this functional comb-shaped polymer, coating unevenness due to this functional comb-shaped polymer is difficult to occur, and after the coating layer is formed, this functional comb-shaped polymer does not bleed over time. It also becomes less likely to occur.

(2) The above-mentioned products having polar functional groups in the branched chains have good stainability with supports, especially organic polymer supports such as polyester films, so this comb-shaped polymer can be used as a magnetic layer, etc. When used in a coating layer, its adhesion is improved and powder falling off can be reduced. Furthermore, when this functional comb-shaped polymer having a polar functional group is included in a coating material, it can stain highly polar particles such as magnetic powders well, thereby improving its dispersibility and dispersion stability.

The functional comb-shaped polymer used in the present invention is a magnetic paint,
It is used in an amount of 0.011 parts by weight to 10 parts by weight per 100 parts by weight of solid content in paints such as back coat layer paints and undercoat paints. In order to improve lubricity, it is particularly preferable to
0.05% to 3% by weight, 0.05% by weight to improve adhesion.
The content is 2% by weight to 5% by weight, and 0.1% to 5% by weight for improving dispersibility.

As these functional comb-shaped polymers, for example, Aron G series manufactured by Takuyasei Co., Ltd. can be used. The contents of each product in the Aron G series and the main effects when used in magnetic paints, back coat layer paints, and undercoat paints are as follows.

The reason why polymers containing fluorine and silicon exhibit good lubricity is that they have surface active functions similar to those of fluorine-based lubricants and silicone-based lubricants, which are generally known as lubricants. However, such functional comb-shaped polymers have a low molecular weight like these commonly known Ill lubricants, and do not stain with other ingredients such as binders, but are easy to coat. There is little migration in the layer, and as a result, it can bring about the remarkable effect that it does not easily cause the blooming phenomenon that occurs with general lubricants. In addition, polymers containing carboxyl groups and hydroxyl groups exhibit good adhesion and dispersibility because these polar groups have an affinity with the polar groups of polymers used as supports, such as polyethylene terephthalate. This is thought to be due to the fact that the adhesive strength of the polymer to the support can be increased. For the same reason, it has a high affinity with relatively polar, for example, magnetic powder, and can improve its dispersibility and dispersion stability.

The functional comb-shaped polymer used in the present invention has different main functions, that is, lubricity, adhesion, and dispersibility as described above, depending on the type of group in its branched chain, but in order to exhibit a combination of these properties, Functional comb-shaped polymers having respective functions may be mixed and used.

When the functional comb-shaped polymer used in the present invention is contained in a magnetic layer, it is used together with at least magnetic powder, but it is preferably used together with a binder resin that is generally used in the magnetic layer.

The magnetic powder and resin described below are used for these magnetic powders and binder resin, and the amount of binder resin used is 5 to 400 parts by weight per 100 N of magnetic powder.
Preferably, the amount is 10 to 200 parts by weight in terms of recording density and mechanical strength of the magnetic layer containing it. If the binder resin exceeds this ratio, the recording density will decrease,
If it is too small, the strength of the magnetic layer will be poor, resulting in undesirable situations such as decreased durability and powder falling off. The above-mentioned comb-shaped polymer is used in the above-mentioned ratio with respect to such magnetic powder and binder resin.

A magnetic paint is used to form the magnetic layer of the magnetic recording medium according to the present invention, and the following method can be used to prepare this paint.

(1) Magnetic powder, the above-mentioned functional comb-shaped polymer, and binder resin solution are mixed in a suitable solvent and dispersed in a ball mill or sand mill to form a paint.

(2) A solution prepared by dissolving the above-mentioned functional comb-shaped polymer in an organic solvent such as toluene, methyl ethyl ketone, ethyl cellosolve, acetone, cyclohexanone, tetrahydrofuran, methanol, etc. is added to a dispersion liquid in which magnetic powder is dispersed in a resin solution, and the mixture is stirred. do.

In order to produce the magnetic recording medium of the present invention, coating is applied to a support described later by a conventional method described later. The magnetic layer coated on such a support is dried while being subjected to a treatment to orient or randomly orient the magnetic powder in the layer, if necessary. Further, if necessary, the magnetic recording medium of the present invention is prepared by subjecting it to surface smoothing or cutting it into a desired shape.

The magnetic recording medium thus formed has a slipperiness, a slipperiness, and
Adhesion to the support and dispersibility of magnetic powder can be improved. Moreover, there is no possibility that a blooming phenomenon will occur over time.

Examples of the magnetic powder used in the magnetic layer in the present invention include γ-Pe203. Co-containing r-Fe20a.

Co-adhered r-Pea 04 , Fe304 , Go-containing F 0/l.

Co-coated FeB O4, -CrO2, etc. oxide magnetic powder, Fe, Ni, Go, Fe-Ni alloy, Fe-N1-
P alloy, Fe-N1-C.

alloy, Fe-Mn-Zn alloy, Fe-Ni-Zn alloy,
Fe-Co-Ni-Cr alloy, Fe-Co-N1-P alloy, Co-Ni alloy, Co-P alloy, etc. Fe, Ni,
Examples include various ferromagnetic powders such as metal magnetic powders containing Co as a main component. Examples of additives for these metal magnetic powders include SI-C++, Zn, 8x, and p.

Elements such as Mn and Cr or compounds thereof may be included. In addition, we also offer 60,000 products such as barium ferrite.
Light powder, iron nitride, is also used.

Binder resins that can be used in the magnetic layer include thermoplastic resins, thermosetting resins, reactive resins, electron beam curable resins, and mixtures thereof.

The thermoplastic resin used as the binder resin has a softening temperature of 150°C or less and an average molecular weight of io, oo.

~200,000, with 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, acrylic ester-acrylonitrile copolymer, acrylic ester-vinylidene chloride copolymer, acrylic ester-styrene copolymer, methacrylic ester-acrylonitrile copolymer,
Methacrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-styrene copolymer, urethane elastomer, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, acrylonitrile-cyclodiene copolymer, polyamide resin, polyvinyl butyral, cellulose Derivatives (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 synthesis Rubber-based thermoplastic resins and mixtures thereof are used.

These resins are disclosed in Japanese Patent Publications Nos. 37-6877 and 39-1.
No. 2528, No. 39-19282, No. 4oL 534
No. 9, No. 40-20907, No. 41-9463, No. 41-14059, No. 41-16985, No. 42-6
No. 428, No. 42-11621, No. 43-4623, No. 43-15206, No. 44-2889, No. 44
-17947, 44-18232, 45-14
No. 020, No. 45-14500, No. 47-18573
No. 47-22063, No. 47-22064, No. 47-22068, No. 47-22069, No. 47-
22070, U.S. Patent No. 48-27886, U.S. Patent No. 3,144,352, U.S. Patent No. 3,419.420, U.S. Pat.
It is stated in the specification of the No.

The thermosetting resin or reactive resin used is one that has a molecular weight of 200,000 or less in the state of a coating solution and becomes insolubilized by a reaction such as condensation or addition after coating and drying. Among these resins, those that do not soften or melt before the resin is thermally decomposed are preferred. Specifically, for example, phenol resin, phenoxy resin, epoxy resin, polyurethane curable resin, urea resin, melamine resin, alkyd resin, silicone resin, acrylic reaction resin, vinyl chloride-vinyl acetate resin, methacrylate copolymer. and diisocyanate prepolymers, mixtures of high molecular weight polyester resins and incyanate prepolymers, urea formaldehyde resins, mixtures of polyester polyols and isocyanates, polycarbonate-type polyurethanes, polyamide resins, low molecular weight glycols, high molecular weight diols, and triphenylmethane triisocyanates. mixtures of polyamine resins, polyamine resins, and mixtures thereof.

These resins are disclosed in Japanese Patent Publications Nos. 39-8103 and 40-97.
79 No. 41-7192, No. 41-8016, No. 4
No. 1-14275, No. 42-18179, No. 43-1
No. 2081, No. 44-28023, No. 45-1450
No. 1, No. 45-24902, No. 46-13103,
No. 47-22067, No. 47-22072, No. 47
-22073, 47-28045, 47-28
No. 048, No. 47-28922, No. 58-405■,
Japanese Unexamined Patent Publication No. 57-31919, No. 58-60430, Japanese Patent Application No. 58-151964, No. 58-1206
No. 97, No. 5B-120698, U.S. Patent No. 3
, No. 144,353, No. 3゜320.090, No. 3. '437,510, '3,597,273,
Same No. 3,781,210, Same No. 3. ,'731,21
It is stated in each specification of No. 1.

Examples of electron beam irradiation-curable resins include unsaturated prepolymers,
For example, maleic anhydride type, urethane 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, phosphate ester acrylic type, aryl type , hydrocarbon type, etc.

These are binder resins used together with oxide magnetic powders or ferromagnetic metal powders, and preferred examples of those used with these ferromagnetic metal powders include phenoxy resins, epoxy resins, and polyurethane resins. The reason why phenoxy resin is used as a dispersion medium for metal magnetic powder is to explain bisphenol and high molecular weight polyhydroxy ether made from epichlorohydrin, which is chemically stable.
It is not easily decomposed even by metallic magnetic powder. Furthermore, since it has a high concentration of hydroxyl groups along the main chain, it has excellent dispersibility of magnetic powder and excellent crosslinking properties. In addition, when it is included as a binder in a magnetic layer, it can provide appropriate softness, and the liquid phase does not change suddenly to a solid phase even with a slight temperature change, so the mechanical properties of the surface do not change. It is possible to provide a magnetic layer with excellent surface properties. It is particularly preferable to use phenoxy resin in combination with polyurethane.

Furthermore, in order to improve the durability of the magnetic layer of the magnetic recording medium according to the present invention, the bank coat layer can contain various curing agents, for example, isocyanate.

Aromatic isocyanates that can be used include, for example, tolylene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), xylylene diisocyanate (XDI), metaxylylene diisocyanate (MXDI), and the addition of these isocyanates with active hydrogen compounds. The average molecular weight is preferably in the range of 100 to 3,000.

On the other hand, examples of aliphatic isocyanates include hexamethylene diisocyanate (HMDI), lysine isocyanate, trimethylhexylylene diisocyanate copolymer (MDI), and adducts of these incyanates and active hydrogen compounds. Among these aliphatic isocyanates and adducts of these isocyanates and active hydrogen compounds, those having a molecular weight in the range of 100 to 3,000 are preferred.

Among the aliphatic isocyanates, non-alicyclic isocyanates and adducts of these compounds with active hydrogen compounds are preferred.

In addition, examples of alicyclic isocyanates among aliphatic incyanates include methylcyclohexane-2,4-
Diisocyanate (Structural Formula) % Formula % (Structural Formula) Examples include isophorone diisocyanate and its adduct of an active hydrogen compound.

Examples of the adduct of the above-mentioned isocyanate and an active hydrogen compound include an adduct of a diisocyanate and a trivalent polyol. Polyisocyanates can also be used as curing agents, including, for example, a pentamer of diisocyanate, a decarboxylation compound of 3 moles of diisocyanate and water, and the like. Examples of these include adducts of 3 moles of tolylene diisocyanate and 1 mole of trimethylolpropane, 3 moles of metaxylylene diisocyanate and 1 mole of trimethylolpropane.
These include a molar adduct, a pentamer of tolylene diisocyanate, a pentamer consisting of 3 moles of tolylene diisocyanate and 2 moles of hexamethylene diisocyanate, etc., and these can be easily obtained industrially.

Among these isocyanates, it is preferable to use aromatic isocyanates and aliphatic isocyanates in combination, for example, from the viewpoint of film properties of the magnetic layer.

In order to form the magnetic layer of the magnetic recording medium of the present invention using these isocyanates, a coating material is prepared by mixing and dispersing the above-exemplified binder resin and, if necessary, various additives described later in an organic solvent. This is coated with the isocyanate (-F) (aromatic isocyanate and aliphatic isocyanate may be used in combination) on a support such as a polyester film, and dried if necessary.

In this case, the amount of isocyanate added is preferably 5 to 60% by weight based on the binder. If it is less than 5% by weight, the coating film tends to be insufficiently cured, and if it is more than 60% by weight, the coating film becomes too hard, which is not preferable.

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

For example, dispersants include lecithin; fatty acids (R ,,C0
0I (R represented by is a saturated or unsaturated alkyl group having 7 to 17 carbon atoms); alkali metal of the above fatty acid (
Li, Na, K, etc.) or alkaline earth metals (Mg,
Examples include metal soaps made of Ca, Ba, etc.).

In addition, higher alcohols having 12 or more carbon atoms, sulfuric esters, and the like can also be used. Moreover, commercially available general surfactants can also be used. Further, combinations of sulfonic acid salts of succinic acid esters (including ethylene glycol nistermo), polycarboxylic acids of maleic acid copolymers, amine surfactants, and polyoxyalkylene glycols can also be used. These dispersants may be used alone or in combination of two or more. These dispersants are magnetic powder 100
It is added in an amount of 1 to 20 parts by weight. These dispersants are described in Japanese Patent Publication No. 39-28369, No. 4
No. 4-17945, No. 48-xsooi, U.S. Patent No. 3,587,993, U.S. Patent No. 3゜470.02
It is stated in the Specification No. 1, etc.

As the camping agent, known titanate camping agents, silane camping agents, etc. may be used in combination.

Among titanium-based coupling agents, a hexa-coordinated titanate-based camping agent is preferable, and a hexa-coordinated coupling agent whose general formula is (R-OATr CP (OR') A compound represented by 20H)2'4 (R and P' are a linear or branched saturated alkyl group, or R is a linear or branched saturated alkyl group and i' is an aryl group) is preferred. Examples of this compound include the following (1) and (2).

(]) Tetraisopropyl bis(dioctyl phosphite) titanate (2) Tetraoctyl bis(ditridecyl phosphite) titanate (CaH+70 +Ti (P +0C13H27)2
011) Molybdenum disulfide, tungsten disulfide, fatty acid esters consisting of monobasic fatty acids with 12 to 16 carbon atoms and monohydric alcohols with 3 to 12 carbon atoms, monohydric alcohols with 17 or more carbon atoms, A fatty acid ester consisting of a basic fatty acid and a monohydric alcohol having a total number of ζ carbons of 21 to 23 is used. It is added in an amount of 2 to 20 parts by weight.

These are described in Japanese Patent Publication No. 43-23889.

In addition, commonly used abrasive materials include fused alumina, silicon carbide, chromium oxide, corundum, artificial corundum, diamond, artificial diamond, garnet, emery (main ingredients are corundum and magnetite), titanium dioxide, etc. be done.

These abrasives have an average particle diameter of 0.05 to 5 .mu.m, particularly preferably 0.1 to 2 .mu.m. These gf abrasives are added in an amount of 1 to 20 parts by weight per 100 parts by weight of magnetic II'A. These abrasives are disclosed in Japanese Unexamined Patent Publication No. 49-115510 and US Patent No. 3.
0 (Publication No. 17,807, Publication No. 3,041,196, Publication No. 3, 687.725, British Patent No. 1,1
Publication No. 45,349, West German Patent (DT-PS)
No. 853,211.

In addition, antistatic IL agents include conductive powders such as carphone black, graphite, tin oxide-antimony oxide compounds, titanium oxide-tin oxide-antimony oxide compounds, and carphone furanoku graft polymers; natural interfaces such as zabonin, etc. Active agent: Nonionic surfactant such as alkylene oxide type, glycerin type, glycidol type; Cationic surfactant such as pyridine and other heterocycles, phosphonium or sulfonium type; Carboxylic acid, sulfonic acid, phosphoric acid, sulfuric acid ester group, phosphoric acid Anionic surfactants containing acidic groups such as ester groups; amino acids, aminosulfonic acids,
Examples include, but are not limited to, amphoteric activators such as sulfuric acid or phosphoric acid esters of amino alcohols.

Surfactants that can be used as antistatic agents include U.S. Pat. No. 2,271,623, U.S. Pat. 2,676°924, 2.676, 975
No. 2,691,566, No. 2,727,86
No. 0, No. 2.730.498, No. 2,742°37
No. 9, No. 2.739.891, No. 3.068.1
No. 01, ff.13.158.484, ff.3.2O
L253 No. 3,210, 191, No. 3,29
No. 4,540, No. 3,415,649, No. 3,4
4L413, 3,442,654, West German Patent Publication (OLS) L942.665, British Patent No. 1
,077.

317, 1,198,450, etc., as well as "Synthesis of surfactants and their applications" by Ryohei Oda et al.
(Maki Shoten 1964 edition): Hachi, Sei, Bayley [Surface Active Agent] (Interscience Publication Inc. 1958 edition):
TR Sisley, "Encyclopedia of Issue - Fesactive Agents Volume 2" (Chemical Publications Company 1964 edition): "Surfactant Handbook" 6th edition (Sangyo Tosho Co., Ltd. December 20, 1964)
etc. are listed on the bottom.

These surfactants may be added alone or in combination. These are used as antistatic agents, but may also be used for other purposes, such as dispersion, improving magnetic properties, improving lubricity, and as coating aids.

” - The solvents added to the paint or the diluting solvents used during application of this paint include acetone, methyl ethyl ketone,
Ketones such as methyl isobutyl ketone and cyclohexanone; alcohols such as methanol, ethanol, propatool, butanol; esters such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, and ethylene glycol monoacetate; glycol cimedylether and ethers such as glycol monoethylconythirane; aromatic hydrocarbons such as henzene, toluene, and xylene; and halogenated hydrocarbons such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, and dichlorohensen.

Magnetic powder, the above binder resin, dispersant, '/w
J-lubricants, abrasives, antistatic agents, solvents, etc. are kneaded into a magnetic paint.

During kneading, the magnetic powder and each of the above-mentioned components are fed into a kneading machine either simultaneously or sequentially. For example, there is a method in which magnetic powder is first added to a solution containing a dispersant and kneaded for a predetermined period of time, and then the remaining components are added and kneaded continuously to obtain a magnetic paint.

Various kneaders are used for cross-mixing and dispersion. For example, two-roll mill, three-roll mill, ball mill, pebble mill, Santoclinter, Szc4vari attritor, high-speed impeller dispersion machine, high-speed stone mill, high-speed tE percussion mill, dispenser kneader, high-speed mixer,
Homogenizers, ultrasonic dispersers, etc.

The technology related to crosstalk dispersion is described in T. C. I'ain4 Flow and Pigment D by PATTON
espersion 2nd Ed. (1979 J.
Ohn Willey & Sons). It is also described in U.S. Patent Nos. 2,581,414, 2,855, and 156.

The above-mentioned magnetic paint consists of a magnetic powder, a binder resin, the organic powder used in the above-mentioned present invention, and the various additives and solvents mentioned above as needed. No. 15, No. 39-26794,
No. 43-186, No. 47-28043, No. 47-2
No. 8045, No. 47-28046, No. 47-2804
8, No. 41-31445, No. 4B-11,162, No. 48-21331, No. 4B-33683, West German Patent Publication No. 2060655, etc. can also be used.

In addition, as a support, polyethylene telecrate,
Examples include polyesters such as polyethylene-2,6-naclate, polyolefins such as polypropylene, cellulose derivatives such as cellulose triacetate and cellulose diacetate, and plastics such as polyamide and polycarbonate. Metals such as Zn, glass, BN, Si carbide, ceramics such as porcelain, ceramics, etc. can also be used.

The thickness of these supports is about 3 to 100 μm in the case of a film or sheet, preferably 5 to 50 μm,
In the case of a disk or card, the diameter is about 30 μm to 10 mm, and in the case of a drum, the diameter is cylindrical, and the shape is determined depending on the record to be used.

Further, the support may be in any form such as a tape, sheet, card, disk, or drum, and various materials may be selected as necessary depending on the form.

Application methods for applying the above paint onto the support include air doctor coating, blade coating, air knife coating, squeeze coating, impregnation coating, reverse roll coating, transfer roll coating, gravure coating, kiss coating, cast coating, and spray coating. Coats etc. can be used, but are not limited to these. Specific explanations of these are described in detail in "Coating Engineering" (published by Asakura Shoten in 1972).

The orientation magnetic field used to orient the magnetic layer is approximately 500 to 3,500 Gauss in alternating current or direct current, and the drying temperature when applying and drying the magnetic paint is approximately 50 to 100°C.
It is preferable that the degree of

The above explanation deals with the case where the functional comb-shaped polymer is contained in the magnetic layer. When the functional comb-shaped polymer is contained in one or more of the subbing layers provided between the supports, the lubricity of the overcoat layer and the hack coat layer is improved as in 1-. The adhesiveness can be improved, and the adhesiveness of the undercoat layer can be improved. Note that a magnetic recording medium having a layer containing a functional comb-shaped polymer includes cases in which this polymer is contained in the above-mentioned overcoat layer, backcoat layer, and undercoat layer, and also includes cases in which the above-mentioned overcoat layer, backcoat layer, and undercoat layer contain this polymer. If
This also includes cases where this compound is attached to the surface, back coat layer surface, and undercoat layer surface. In addition, this attachment also includes the case where it is attached to a ferromagnetic metal thin film formed by vapor deposition, sputtering, ion blating, or the like.

Of course, additives such as the binder resin, lubricant, antistatic agent, and abrasive that are commonly used in these layers can be used in combination with the hack coat layer, overcoat layer, and undercoat layer. be.

Effects of the Invention According to the present invention, since the magnetic recording medium has a layer containing a functional comb-shaped polymer, excellent moisture retention is achieved. Pt
In addition to providing good properties, it also reduces the plumping phenomenon and uneven coating of the coating liquid, unlike conventional fluorine-based lubricants and silicone-based lubricants. If such a phenomenon can be reduced, it is possible to reduce the possibility that the magnetic head will be contaminated by the additive that has oozed out onto the surface, or that the clean surface of the magnetic recording medium will be contaminated by this magnetic nodule. In addition, it is less likely that excessive exudation of the additive will cause large spacing loss, damage to the magnetic layer due to excessive tension on magnetic recording media, such as magnetic tape, and occurrence of powder falling off. . Furthermore, as a result of the improved adhesion of the coating layer, particularly the magnetic layer, to the support, it is possible to reduce the amount of magnetic powder falling off.

As a result, output fluctuations, dropouts, etc. of the magnetic recording medium can be reduced, various electromagnetic conversion characteristics such as S/N can be maintained well, and the winding appearance is also improved, so that the output characteristics when reusing the medium can be improved. Electromagnetic conversion characteristics can also be prevented from changing. In this way, magnetic recording media can maintain their performance even when used under harsh conditions such as high-speed operation, fast-forward playback, and rewinding, meeting the recent demands for high-density recording and further improvement in durability. I can do it.

EXAMPLES Next, the present invention will be described in detail with reference to Examples, but the present invention is not limited thereto.

Example 1 Compositions in the Example 1 column of Table I (parts by weight are shown).

The same applies hereinafter) is placed in a ball mill and dispersed to prepare a dispersion. This dispersion was filtered through a 1 μm filter,
5 parts by weight of a polyfunctional isocyanate is added to this filtrate and mixed to prepare a magnetic paint.

This magnetic paint was coated on a support (polyethylene terephthalate film base) to a thickness of 5 μm using a reverse roll coater, dried, supercalendered, and slit into 1/2 inch pieces to create the videotave of Example 1. did.

Examples 2 to 4 Examples were carried out in the same manner as in Example 1, except that instead of using the composition in the Example 1 column of Table 1, the compositions in the Examples 2 to 4 columns of Table 1 were used. Created 2-4 videotapes.

Comparative Example 1 A videotape of Comparative Example 1 was prepared in the same manner as in Example 1, except that the composition in the Comparative Example 1 column of Table 1 was used instead of the composition in the Example 1 column of Table 1. did.

Example 5 A 1 μm back coat layer (B
C layer) was formed to produce video tapes of Examples.

Comparative Example 2 A 1 μm bank coat layer (BC layer) was formed on the back side of the videotape of Comparative Example 1 using the composition in the Comparative Example 2 column of Table 1 to create a videotape of Comparative Example 2.

Each videotape of Examples 1 to 5 and Comparative Examples 1 to 2 was tested for each item shown in Table 2, and the results are shown in the corresponding columns.

The measurement method is as follows.

(al chroma S/N: chroma signal (3,58MHz)
is set to 0.714Vp-P and recorded on the luminance signal,
This recording is played back, and only the chroma signal is extracted, and the ratio between its effective value (S') and the noise level (N) when the chroma signal is removed is expressed.

ib) Lumi5/N (dB): 50%-old TE (
β) or 100%-old TE (VB2) signal was recorded and the output and noise level when played back were measured using a noise meter. The measured values in the table are relative values when the value of Comparative Example 1 is set to OdB.

tel skew value (μ5ec): A value indicating the distortion of the video screen; the smaller the value, the smaller the distortion.

Measured according to the trial decision.

1 dl static image life (sin): The time until the image disappears after stopping the running of the tape in NV-6200 manufactured by Matsushita Electric Co., Ltd. was measured.

(e) Bleed-out: The magnetic tape was held at 10°C for 12 hours, then held at 40°C and 80% relative humidity for 12 hours, and this process was repeated 10 times to observe the surface of the coating layer with a microscope. Those with oil-like 1ξ discharge were classified as [Yes J], and those without were designated as [No J].

ff) Friction coefficient: Using a rotating drum type surface property measuring device manufactured by Shinto Kagaku Co., Ltd., a load of 3 hours with a 4 mm diameter iron,
The measurement was performed at a rotation speed of 66, 9 rpm.

ig) Volume: Video deck (equipment name β: 5ONY)
SL-520, VB2: VICTORIIR-71
00) The tape was repeatedly run 400 times and evaluated on a four-level scale to determine whether the edges of the tape were aligned on one plane.

(h) Adhesiveness: 1.5 Kg in a glass tube with a diameter of 30 mm
Winding the magnetic tapes of the above examples and comparative examples with heavy tension,
6m adhesion determined by the presence or absence of adhesive force when unwinding the tape after being left for 24 hours at a temperature of 60°C and a relative humidity of 80%: Stick tape on the coating layer and peel it off, and the coating layer peels off from the support. The degree to which this happens was evaluated on a four-level scale.

From the results in Table 2, the videotapes of Examples 1 to 5 have no bleed-out, long still image life (and good abrasion resistance, good winding form and coating layer adhesion, and electromagnetic tape such as chroma S/N). It can be seen that while the tape of Comparative Example I has good conversion characteristics, it bleeds out, and all other properties are inferior to the tape of Example. It can be seen that while there is no adhesion between the backcoat layer and the magnetic layer, the latter has both, has a large coefficient of dynamic friction, and is inferior in other properties.

In addition, when observed with an electron microscope, the dispersibility of the tape of Example 2 was superior to that of the tape of Comparative Example 1. Further, coating unevenness was observed on the surface of the magnetic layer of the tape of Comparative Example 1.

(The following is the margin of this page) Table 2 May 21, 1980

Claims (1)

[Claims] (1) A magnetic recording medium characterized by having a layer containing a functional comb-shaped polymer containing at least one of a fluorine atom, a silicon atom, and a polar functional group.