JPS59129937A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium which is dispersed uniformly with magnetic powder in a magnetic layer and has excellent performance by using the magnetic powder obtainable by dispersing ferromagnetic powder in a basic electrolyte soln. then adding a specific cationic surface active agent thereto and redispersing the same. CONSTITUTION:Ferromagnetic powder is dispersed on a basic electrolyte soln. of NaOH, etc. and the surface thereof is electrified negative. The cationic surface active agent expressed by the formulas I , II [R<1> is 1-30C (substd.) alkyl or cycloalkyl, 6-30C (substd.) aryl, heterocyclic ring, R<2>, R<3> are 1-20C (substd.) alkyl or H, R<4> is 1-10C (substd.) alkyl, n is 0-4 integer, Q is N or C and forms a satd. 5-6-membered ring together with N, A is an org. or inorg. acid, (m) is a real number] is added to said powder and the powder is redispersed. A magnetic layer contg. the magnetic powder formed by adding a hydrophobic solvent to the magnetic powder subjected to the surface treatment in the above- mentioned way to migrate said powder to the solvent layer together with a binder resin is provided. The magnetic powder treated in such a way is uniformly dispersed and a magnetic recording medium having an excellent surface characteristic, wear resistance, etc. is obtd.

Description

[Detailed description of the invention]

(a) Industrial Application Field: The present invention relates to a magnetic recording medium, and more particularly to a magnetic recording medium that has improved dispersibility of ferromagnetic powder, has excellent surface properties and wear resistance, and is suitable for high-density recording. (b) Prior art: Conventionally, in magnetic recording media such as recording tapes, video tapes, and 70-tube discs, ferromagnetic powder is coated on a support such as polyethylene terephthalate using vinyl chloride-vinyl acetate copolymer, cellulose resin, or A magnetic paint obtained by kneading with a binder such as an epoxy resin or a polyurethane resin was applied to form the entire ferromagnetic layer. However, the dispersibility of the ferromagnetic powder was not sufficient even when these binders were used alone or in combination. Therefore, the surface properties and wear resistance of conventional magnetic recording media have not been fully satisfactory. Particularly in video cameras that require short wavelength recording, poor dispersion of ferromagnetic powder in the ferromagnetic layer leads to deterioration of the S/N ratio and decrease in sensitivity.
Since the magnetic head 1 is in violent contact with the magnetic head 1 during recording and reproduction, the magnetic coating is worn out by repeated use, and the ferromagnetic powder contained in the coating is likely to fall off, resulting in undesirable problems such as clogging of the magnetic head. It had consequences. For this reason, various additives are used for the purpose of improving the dispersibility of ferromagnetic powder and improving the wear resistance. For example, JP 41-18064, 43-186, 4-3-669, 47-15624, JP 49
-53402, 49-58804, 49-84
No. 405, No. 51-40904, No. 52-70811
As stated in each publication, higher fatty acids, fatty acid amides, fatty acid esters, higher alcohols, metal soaps, sulfuric esters of higher alcohols, polyethylene oxide, and lentene are added to the magnetic paint containing ferromagnetic powder and binder. A magnetic recording medium is produced by coating a support with this magnetic paint. However, it has been difficult to obtain a magnetic recording medium with desirable characteristics simply by adding these additives during the production of magnetic paint. For example, the use of large amounts of these additives can lead to poor results. Further, after the ferromagnetic layer was formed, additives gradually oozed out, and the magnetic properties of the magnetic layer and the dispersibility of the ferromagnetic powder were never satisfactory. Therefore, in order to improve the dispersibility of ferromagnetic powder without causing the phenomenon of "1 pluming", for example,
As described in the specification of the publication No. 7-1048, it has been proposed to pre-treat the ferromagnetic powder with a surfactant for surface treatment. A hydrophobic surfactant such as 1-nontene is added to an organic solvent to prepare an active agent solution, and the ferromagnetic powder to be treated is added thereto and dispersed, then filtered and air-dried. Further, the powder was dried under reduced pressure to obtain a surface-treated ferromagnetic powder. According to this method,
Although the "blooming" phenomenon was certainly suppressed, there was a problem in that the dispersibility of the ferromagnetic powder worsened. The conventional method of simply immersing ferromagnetic powder in a surfactant solution and dispersing it has the problem that a satisfactory dispersion state cannot be achieved. (c) Object of the invention: An object of the invention is to provide a novel magnetic recording medium that overcomes the above-mentioned drawbacks. That is, an object of the present invention is to provide a magnetic recording medium that has improved dispersibility of ferromagnetic powder, has excellent surface properties and wear resistance, and is suitable for high-density recording. (d) Structure of the invention: The object of the present invention is to provide a magnetic recording medium in which a ferromagnetic layer containing surface-treated ferromagnetic powder is provided on a support,
As a surface-treated ferromagnetic powder, after dispersing the ferromagnetic powder in a basic electrolyte solution, the following general formula (1) or (TI)
This can be achieved by using a redispersed surfactant having the structure shown below. The object of the present invention is to provide a magnetic recording medium in which a ferromagnetic layer containing a surface-treated ferromagnetic powder is provided on a support, in which a ferromagnetic layer is provided in a basic electrolyte M solution as a surface-treated ferromagnetic powder. After dispersing the powder, the following general formula (1) or (
After performing redispersion treatment with an interfacial agent having the structure represented by II), adding a hydrophobic organic solvent to the dispersion treatment solution and transferring the ferromagnetic powder to the organic layer, the surface-treated ferromagnetic powder taken out is used. The general formulas (1) and (II) are respectively R1-N -R2-m'A (1)
Ise3 and (R'). and R1 is a saturated or unsaturated alkyl group having 1 to 30 carbon atoms (which may be linear or branched, or may be a cycloalkyl group, and a substituted amine as a substituent) or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms (heterocyclic compound) It's okay,
In addition, the above substituent may have a saturated or unsaturated substituted or unsubstituted aryl group and/or a substituted amino group having 1 to 24 carbon atoms), and R2 and R3 are each carbon Number of atoms 1~20111! il
represents a saturated or unsaturated substituent or an unsubstituted alkyl group or a hydrogen atom, R4 represents a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, and n is a positive 0 to 4 strain number υ, Q represents a nitrogen atom or carbon atom, represents a 5- or 6-membered monkey saturated by Q-N, human represents an organic or inorganic acid, m represents a positive real number O basicity As an electrolyte, NaOHXKO, HXNa5P
O4, Na4P*Ot, Na<PaChz, N'a2S
ios, Na4S in4, N12 WOa, K
s P 04 , K4h 07, K4PaoI2, R2
8ios, K4S 104, KtWOa, etc. All of these electrolytes charge the surface of the ferromagnetic powder negatively. The concentration of this basic electrolyte depends on the type of electrolyte and the ferromagnetic powder used. Although it depends on the isoelectric point, in order to make the surface of the ferromagnetic powder negatively charged, it is necessary to use an electrolytic solution with a concentration that is higher than the isoelectric point of the ferromagnetic powder. The value is preferably 10.5 to 13.0, more preferably 10.
, 5 to 12.5. If it is less than 10.5, the charging effect is insufficient, and if it is more than 13.0, the basic surfactant that follows may be decomposed.
For 0gr, 20 to 500 rILl of electrolyte solution are used, preferably 50ml to 2,000ml. Examples of the dispersion method for dispersing the ferromagnetic powder in the electrolyte bath include methods using a ball mill, a sand grinder, a high-speed impeller disperser, a high-speed mixer, a homogenizer, and the like. It is believed that by dispersing the ferromagnetic powder in an electrolyte solution, shear force acts effectively on the aggregated powder, thereby reducing the proportion of the aggregated ferromagnetic powder. Water alone is often sufficient as a solvent for the electrolyte solution according to the present invention, but if necessary, various hydrophilic solvents, such as linear or branched alcohols or alcohols having 1 to 8 carbon atoms, may be used. = c-chill l) Louis ld Alcohols such as polyalcohols (e.g., methanol, ethanol, ethanol, ethylene glycol'4): Ketones having 3 to 6 carbon atoms (e.g., acetone, methyl ether ketone, etc.) ): Hydrophilic ether such as tetrahydrofuran or dimekizhen: Nitrogen-containing hydrophilic solvent such as N-methylpyrrolidone, dimethylformamide, dimethylacetamide, pyridine, etc., preferably up to 50 parts by weight per 100 parts by weight of water. is mixed in an amount of 20 parts by weight or less. As the basic electrolyte solution, an aqueous electrolyte solution is particularly preferred. After dispersing the ferromagnetic powder in a basic electrolyte solution, the present invention treats the ferromagnetic powder with a cationic surfactant represented by the general formula % (1) ( ). However, in general formulas (1) and (II), R1
is a saturated or unsaturated alkyl group having 1 to 30 carbon atoms □ (which may be linear or branched, or may be a cycloalkyl group, and a substituted amine group or a substituted or unsubstituted aryl group as a substituent) or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms (which may be a heterocyclic compound; A saturated or unsaturated substituted or unsubstituted aryl group having ~20 carbon atoms (it may be a multi-ring compound, and the above substituents include saturated or unsaturated substituted aryl groups having 1 to 20 carbon atoms) or may have 6 unsubstituted aryl groups or a substituted amino group), and R2 and R3 each represent a saturated or unsaturated substituted or unsubstituted aryl group having 1 to 20 carbon atoms, or Represents a hydrogen atom, and preferably the total number of carbon atoms of R1, R2, and R3 is 20 or more and 50 or less. Also, H1, R2, and R3 are not all hydrogen atoms. R4 has 1 to 10 carbon atoms. represents a substituted or unsubstituted aryl group having The exemplified compounds included are shown in Table 1.
Exemplary compounds included in general formula (II) are listed in Table 2. In any of the exemplified compounds in the margins below, m represented by 771A is (number of -class amine groups)X1+(number of secondary amino groups)xl
+C number of tertiary amine groups) x 1 or less 9 positive real numbers can be taken. For example, the exemplified compound (1)-20
ζIf you get stuck, CH3-(CH2), -NH-CH2C
H2-NH2-, CH3CH3C00H,5,1,0,
It can be a real number within m62, such as 1, '2.15.1.8.2.0. The same applies to other exemplified compounds. Among the surfactants of the type represented by the general formula (I), preferred are those having two or more amino groups (which may be primary, secondary, or tertiary), and more preferred are , R-N-Y"-N-R-, A
(■) 13.1 几 R32 R-N-Y-N-Y2-N-4-mA (J) or fL"-N-Y'-N-Y"-N-Y3-N-R2 cloud mA ( y) A compound represented by the general formula 1 1 1 1 R1" B, "'R33B+". Also preferred is a type in which N has two or more or at least one -NN- group. For example, a preferred compound is a compound represented by the general formula %) () (). However, the general formula (I), (
In IV), (V), (■), (■), (■), R
is a saturated or unsaturated substituted or unsubstituted alkyl group having 6 to 20 carbon atoms or a substituted or unsubstituted aryl group having 6 to 24 carbon atoms (as the above substituent, 18 saturated or unsaturated substituted or unsubstituted alkyl groups), and JR, R, R, R, each have 1 to 18 carbon atoms.
, R4 represents a substituted or unsubstituted alkyl group having 1 to 7 carbon atoms, and n is an integer of 0 to 4. , more preferably J
The total number of atoms of R and H is 5 to 50, and 1\l-1-Y2-1 y3- is a divalent linking group having 1 to 20 carbon atoms (no substituents). ) is a divalent linking group or carbon represented by +L, +cFt2+ (n is 2 or 3, R5 is a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 7 carbon atoms) Represents a divalent linking group having an f-substituted or unsubstituted aryl group having 6 to 20 atoms, m represents a real number of 1 to 2 in the general formulas (I) and (VT), and (+V) and (■) represent real numbers from 1 to 4; general formulas (v) and (vm) represent real numbers from 1 to 6; and A has 1 to 20 carbon atoms. Represents saturated or unsaturated carboxylic acids. Compounds belonging to general defects (I) and (If) are not only those having such CH3COOH (, HC, d,
Various organic and inorganic acids such as H□5O4C2)■5C00H and H3PO4 can be used. According to the present invention, by first dispersing in a basic electrolyte solution,
It is believed that a stable adsorption layer of the surfactant is formed on the surface of the ferromagnetic powder by treating the ferromagnetic powder whose surface is negatively charged with the oppositely charged cationic surfactant. The surfactants according to the present invention may be used alone or as a mixture of two or more in any proportion. The amount of surfactant to be used is preferably from 0.05 parts by weight to 50 parts by weight, particularly preferably from 0.1 parts by weight to 10 parts by weight, per 100 parts by weight of the ferromagnetic powder. This is because if the amount is less than 0.05 parts by weight, the effect is not sufficient, and if it exceeds 50 parts by weight, emulsification phenomenon tends to occur. Surfactants can be used by mixing only with water,
In addition, it may be mixed with the hydrophilic solution mentioned in the explanation of the electrolyte solution (the surfactant may be dissolved only in the hydrophilic solvent used for the surfactant), or A surfactant may be mixed with a solvent obtained by mixing water and the above-mentioned hydrophilic solvent in an arbitrary ratio, or a mixture with a hydrophobic organic solvent other than the above-mentioned hydrophilic solvent may be used. When the surfactant according to the present invention is used as the hydrophilic solvent and/or water or a hydrophobic organic solvent, 1 to 30 parts by weight of the surfactant is used as the hydrophilic solvent and/or water or the hydrophobic organic solvent. It is preferable to use 70 to 99 parts by weight of a sterile organic solvent to form a surfactant solution. Therefore, for example, when it is desired to use 5 parts by weight of a surfactant per 100 parts by weight of ferromagnetic powder, for example, the surfactant liquid: 10% by weight (the hydrophilic solvent or water or the hydrophobic organic 50 parts by weight of a mixture of 90 parts by weight of a solvent and 10 parts by weight of a surfactant may be used. In addition, a solution containing a surfactant mixed in a solvent was applied to the ferromagnetic powder 1009r at 20 mA' to 5000 mA.
1, preferably 50 ml-2000 mal. The ferromagnetic powder, surfactant, hydrophilic organic solvent and/or water or hydrophobic organic solvent can be used in various proportions as described above. In the present invention, the ferromagnetic powder in a basic electrolyte solution is dispersed, and then treated with the cationic surfactant having an opposite charge to the surface of the ferromagnetic powder. More preferably, a hydrophobic organic solvent is added to the treatment liquid to transfer the ferromagnetic powder to the organic layer. As a method for transferring to the organic layer, 1. After dispersing the ferromagnetic powder in a basic electrolyte, the above-mentioned surfactant solution is added to the pretreated ferromagnetic powder taken out by filtering the dispersion treatment solution, and the powder is dispersed. The ferromagnetic powder may be transferred to the organic layer by preparing a liquid and adding water, or the ferromagnetic powder may be transferred to the organic layer by adding a hydrophobic organic solvent to the dispersion. ■Furthermore, after dispersing the ferromagnetic powder in a basic electrolyte, add the above-mentioned surfactant liquid to this dispersion treatment liquid to prepare a dispersion liquid, and then process the dispersion liquid by the method of (■) above. The ferromagnetic powder may be transferred to the organic layer by performing the same treatment as described above. There are various modifications, such as allowing migration. In addition, the hydrophobic organic solvent mentioned above has 5 to 5 carbon atoms.
14 linear or branched aliphatic hydrocarbons, alicyclic hydrocarbons having 5 to 11 carbon atoms, substituted (preferred substituents are halogens or alkyl groups) or unsubstituted Examples include aromatic hydrocarbons, cyclic or non-yielding ketones having 4 to 10 carbon atoms, and halogen-containing aliphatic hydrocarbons having 1 to 10 carbon atoms and containing one or more halogen atoms. sexual parameters (generally SP
value) is 7.0 or more and less than 10.0 (25
values in °C) are preferred. Among the hydrophobic organic solvents, the aliphatic hydrocarbons, alicyclic hydrocarbons, aromatic hydrocarbons, and halogen-containing aliphatic hydrocarbons are preferable in terms of operability and ease of separation from the aqueous layer. Among them, aliphatic hydrocarbons, alicyclic hydrocarbons, and aromatic hydrocarbons are more preferred. Examples of the preferred hydrophobic organic solvents include pentane, hexano, heptane,
Examples include octane (all of the above may be direct or branched), cyclopentane, cyclohexane, cyclohephtane, cyclooctane, benzene, I-luene, xylene, carbon tetrachloride, chloroform, methylene chloride, etc. It will be done. Two or more types of hydrophobic organic solvents may be used in combination. The amount of hydrophobic organic solvent used is:
It varies depending on the solvent, but when the surfactant is mixed with a hydrophilic solvent, the ferromagnetic powder
It is preferable to use the surfactant in a range of 20ml to 5,000ml, preferably 50rrLl to 2,000ml per jir.When the surfactant is used in combination with a hydrophobic organic solvent, the amount of water in the surfactant solution is Combined with the amount of hydrophobic organic solvent, 20% for 100.9r of ferromagnetic powder
ml to 5000 ml, preferably 50 ml to 20
It is preferable to use within the range of 0.00 ml, and as long as the amount of the hydrophobic organic solvent in the surfactant solution is within the above-mentioned range, a new hydrophobic organic solvent may be added. By adding a hydrophobic organic solvent, the treatment liquid can be divided into an organic layer (hydrophobic slimy liquid layer) and an aqueous layer (strongly hydrophilic liquid layer).
At this time, the surface-treated ferromagnetic powder that has been sufficiently hydrophobized will migrate to the mechanical layer, and those that have not been sufficiently hydrophobized will be left behind in the water layer. Dispersion ζ of surface-treated ferromagnetic powder according to the present invention obtained by removing
This selectively contains surface-treated ferromagnetic powder that has been sufficiently hydrophobized. Therefore, by removing the solvent from the dispersion and drying it, it is possible to selectively obtain a surface-treated magnetic powder that is sufficiently hydrophobic and has excellent dispersibility. The excellent dispersibility of the surface-treated ferromagnetic powder obtained by the method for producing surface-treated ferromagnetic powder according to the present invention will be explained in detail in the Examples below.
The sedimentation rate of the ferromagnetic powder in n-hexane can be used as a guideline. The excellent dispersibility of the surface-treated ferromagnetic powder has enabled it to be used in the fields of magnetic fluids and magnetic pigments, including the production of magnetic paints with extremely good dispersibility in the production of magnetic recording media, which will be described later. However, its excellent dispersibility makes it widely applicable. Ferromagnetic powder I in a settling tube with an inner diameter of 10 mm and an internal volume of 30 m1.
After adding Ir and thoroughly shaking for 1 minute, and standing quietly for 24 hours, the height of the ferromagnetic powder from the surface of the solution at the interface height with suspended n-hexane is defined as the sedimentation rate, mm ( (per 24 hours), and the sedimentation rate is 0 to 1
If OOmrn1 is preferably O to zomm, it can be said that the ferromagnetic powder provides good dispersibility. In addition, as another example, the sedimentation rate is considered to be a measure of the degree of aggregation (the smaller the value, the lower the rate of aggregation). To find out whether the powder is floating or slightly dispersed, suspend and disperse the powder in various solutions with known surface tension (e.g. water-methanol mixed solvent). When the surface tension of the former solution is applied, the powder can be made hydrophobic, and the root dispersibility with a small hydrophobicity value (in this case, dispersion under hydrophobic conditions) is considered to be good. You can do it. The surface-treated ferromagnetic powder according to the present invention can be prepared by: (1) dispersing the ferromagnetic powder in an electrolyte solution and then removing the ferromagnetic powder; You can take out the ferromagnetic powder from the ferromagnetic powder, add water and/or a hydrophilic solvent, and take it out after treatment. After transferring the ferromagnetic powder to the organic layer, the ferromagnetic powder may be taken out from the organic layer. ■Furthermore, the surface-treated ferromagnetic powder according to the present invention is cross-wired and dispersed in a solvent together with a binder to form a magnetic paint. Then, a magnetic recording medium can be produced by coating the paint on a support to form a ferromagnetic layer.Furthermore, according to the present invention, the dispersion of the surface-treated ferromagnetic powder can be concentrated and dried as necessary. A magnetic recording medium can also be produced by adding a binder to cross-wire and disperse the wires to form a magnetic paint, and then coating the paint on a support to form a ferromagnetic layer. dispersant,
Additives such as lubricants, abrasives, and antistatic agents may also be included. 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. 47-2804.8, No. 47-31445, No. 48-11162, No. 48-21331, No. 48-
It is described in detail in various publications such as Japanese Patent No. 33683 and West German Published Patent Application No. 2060655. As the binder that can be used in the ferromagnetic layer of the magnetic recording medium according to the present invention, conventionally known thermoplastic resins, thermosetting resins, reactive resins, electron beam curable resins, and mixtures thereof are used. . The thermoplastic resin has a softening temperature of 150°C or less, an average molecular weight of 10.000 to 200.000, and a degree of polymerization of about 2.
00 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 acid ester-acrylonitrile copolymer, methacrylic acid ester-hynylidene chloride copolymer, methacrylic acid ester-styrene copolymer, urethane elastomer, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, acrylonitrile-butadiene copolymer Coalescence, polyamide resin, polyvinyl butyral, cellulose U4 (cellulose acetate phthalate, cellulose tiacetate-1, cellulose triacetate, cellulose propionate, nitrocellulose, etc.), styrene-butadiene copolymer, polyester resin,

[Copynyl ether-acrylic acid ester copolymer, amine resin, various synthetic com-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. 40-5349
No. 40-20907, No. 41-9463, No. 4
No. 1-14059, No. 41-16985, No. 42-6
No. 428, No. 42-11621, No. 43-4623, No. 43-15266, 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-
No. 22070, US Pat. No. 48-27886, US Pat. No. 3,144,352, US Pat. No. 3,419,420, US Pat. No. 3,499,789, US Pat. Are listed. The thermosetting resin or reactive resin has a molecular weight of 200,000 or less in the state of a coating liquid, and after coating and drying, the molecular weight becomes infinite due to reactions such as condensation and addition. Among these resins, those that do not soften or melt before the resin is thermally decomposed are preferred. Specifically, for example, phenol resins, epoxy resins, polyurethane curable resins, urea resins, melamine resins, alkyd resins, silicone resins, acrylic reaction resins, mixtures of high molecular weight polyester resins and incyanate prepolymers,
Mixtures of methacrylate copolymers and diisocyanate 1/polymers, mixtures of polyester polyols and polyisocyanates, urea formaldehyde resins, mixtures of low molecular weight glycols/high molecular weight diols/triphenylmethane triisocyanates, polyamine resins and mixtures thereof, etc. It is. These resins are disclosed in Japanese Patent Publications Nos. 39-8103 and 40-97.
No. 79, No. 41-7192, No. 41-8016, No. 41-14275, No. 42-18179, No. 43-
No. 12081, No. 44-2802.3, No. 45-”
No. 14501, No. 45-24902, No. 46. '-1
No. 3103, No. 47-22067, No. 47-2207
No. 2, No. 47-22073, No. 47-28045,
4'7-28048, 47-28922,
U.S. Patent No. 3,144,353, U.S. Patent No. 3,320,0
No. 90, No. 3, 437.519, No. 3,597,
No. 273, No. 3,781,210, No. 3,781
, No. 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 polyfunctional heptadons such as ether acrylic type, urethane acrylic type, epoxy Acrylic type, phosphate ester acrylic type, aryl type, No\idoroka
Examples include ``bon type''. These binders may be used alone or in combination, and other additives may be added as required. The mixing ratio of the surface-treated ferromagnetic powder and the binder according to the present invention is 10 to 10 parts by weight of the binder to 100 parts by weight of the ferromagnetic powder.
It is used in an amount of 400 parts by weight, preferably in the range of 30 to 100 parts by weight. If the amount of binder is too large, the recording density of the magnetic recording medium will be reduced, and 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. Furthermore, in order to improve the durability of the magnetic recording medium according to the present invention, the magnetic layer can contain various curing agents,
For example, polyisocyanates (an example of another curing agent) can be included. As the polyisocyanate, an adduct of diisocyanate and trivalent polyol, or an adduct of diisocyanate
There is a decarboxylation compound of 3 moles of diisocyanate and water. Examples of these include tolylene diisocyanate 3
5 consisting of an adduct of mol and 1 mol of trimethylolpropane, an adduct of 3 mol of metaxylylene diisocyanate and 1 mol of trimethylolpropane, an adduct of tolylene diisocyanate No. 5, and 3 mol of tolylene diisocyanate and 2 mol of hexamethylene diisocyanate. There are decarboxylated products obtained by reacting 3 moles of hexamethylene diisocyanate and 1 mole of water, and these are easily obtained industrially. The ferromagnetic layer may contain additives such as a dispersant, a lubricant, an abrasive, an antistatic agent, and the like in addition to the binder and curing agent described above in the surface-treated ferromagnetic powder ζ according to the present invention. The dispersants used include caprylic acid, capric acid,
Fatty acids with 8 to 18 carbon atoms such as lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, elaidic acid, linoleic acid, and lyric acid (represented by -COOH, where R is 7 to 7 carbon atoms) 17 saturated or unsaturated alkyl groups): alkali metal (Li
, Na, K, etc.) or alkaline earth metals (Mg
, Ca', Bad): lecithin, etc. are used. In addition to these, higher alcohols having 12 or more carbon atoms and sulfuric esters can also be used. Furthermore, the surfactants described in the method for producing the surface-treated ferromagnetic powder according to the present invention can also be used. These dispersants may be used alone or in combination of two or more. These dispersants are added in an amount of 1 to 20 parts by weight per 100 parts by weight of the binder. These dispersants are described in Japanese Patent Publication Nos. 39-28369 and 44-
No. 17945, US Pat. No. 48-15001, US Pat. No. 3,587,993, and US Pat. No. 3,470,021. As a lubricant, silicone oil, carbon blank,
Graphite, carbon black craft polymer, molybdenum disulfide, tungsten disulfide, 12 carbon atoms
Fatty acid ester (so-called wax) consisting of ~16 monobasic fatty acids and 1 filfi alcohol having a total number of carbon atoms of 21 to 23 carbon atoms (so-called wax)
etc. can also be used. These lubricants are added in an amount of 0.2 to 20 parts by weight per 100 parts by weight of the binder. Regarding these, Japanese Patent Publication No. 43-23889, No. 43-23889,
Publications such as No. 81543, U.S. Patent No. 3,470,021
No. 3,492,235, No. 3,497,41
No. 1, No. 3,523,086, No. 3,625,76
0 3.630.772, 3.634.253
No. 3.642.539, No. 3.687.7
Specifications of No. 25, IBM Technical Dis
Closure Bulletin Vol. 9.4
7, page 779 (December 1966): ELH
It is described in KTRONIK 1961 A12, page 380, etc. The abrasives used are commonly used materials such as fused alumina, silicon carbide chromium oxide, corundum, artificial corundum, diamond, artificial diamond, sacrostone, and emery (main ingredients: corantum and magnetite). Ru. These abrasives have an average particle size of 0. Q5~5μ
A size of 0.1 to 2 is particularly preferably used.
μ. These abrasives are added in an amount of 1 to 20 parts by weight based on 1003 parts of the binder. These abrasive materials are disclosed in Japanese Patent Application Laid-Open No. 49-115510, U.S. Patent No. 3.007.807, U.S. Pat.
．． No. 145.349, i) 'Ia% Permit (DT-PS)
No. 853.211. The antistatic agents used include: conductive powders such as graphite, carbon black, and carbon black graft polymers; natural surfactants such as saponin; 7-ion surfactants such as alkylene oxide, chrycerin, and glycidol; high-grade Cationic surfactants such as alkylamines, quaternary ammonium salts, pyridine, other heterocycles, phosphoniums or sulfoniums: Carboxylic acid 1. Sulfonic acid, phosphoric acid, sulfuric acid ester group,
Anionic surfactants containing acidic groups such as phosphate ester groups, diamino acids, aminosulfonic acids, amphoteric surfactants such as sulfuric acid or phosphoric esters of amino alcohols, and the like are used. These surfactants that can be used as antistatic agents are US special f! F No. 2.271.623, F No. 2.240.47
No. 2, No. 2.288.226, No. 2.676, 1
No. 22, No. 2゜676.924, No. 2.676
, No. 975, No. 2,691,566, No. 2.72
No. 7.860, No. 2.730.498, No. 2, 7
No. 42.379, No. 2.739.891, No. 3.
No. 068.101, No. 3.158.484, No. 3
．． 2oi, No. 253, No. 3.210,191, No. 3.294.540, No. 3,415,649,
Same No. 3,441,413, Same No. 3.442.654, Same No. 3.475,174, Same No. 3.545.974
No., West German Patent Publication (01,,S) 1,942,6
65, British Patent No. 1.077, 317, British Patent No. 1.1
98.450, etc., Ryohei Oda et al.
Synthesis of Surfactants and Their Applications J (4fX Shoten 1964 edition): A, W. Bayley, 1-Surface Active Agents'' (Interscience Publications Inc. 1958 edition): ``T, P,
Written by Sisley [Encyclopedia of Saniphus Active Agents Volume 2 J (Chemical Bridge≧Company 1964 edition): "Surfactant Handbook"
It is described in the 6th edition (Sangyo Tosho Co., Ltd., December 20, 1999) and other publications. These surfactants may be added alone or in combination. Although these are used as antistatic agents, they are sometimes applied for other purposes, such as dispersion, improving magnetic properties, improving lubricity, and as coating aids. Solvents for magnetic paint or solvents used when applying magnetic paint include: Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; Alcohols such as methanol, ethanol, propatool, and butanol; Methyl acetate, ethyl acetate, Ester types such as butyl acetate, ethyl lactate, and ethylene glycol monoethyl ether acetate; Glycol ether types such as nigericol dimethyl ether, glycol monoethyl ether, and dioxane; Aromatic hydrocarbons such as benzene, toluene, and xylene; Methylene chloride, ethylene; Halogenated hydrocarbons such as chloride, carbon tetrachloride, chloroform, and dichlorobenzene can be used. Materials for the support include polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate, polyolefins such as polypropylene, plastics such as cellulose triacetate, cellulose derivatives, and polycarbonate, non-magnetic metals such as Zn, etc. Various types of ceramics such as ceramics and new ceramics are 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 disks and cards, the diameter is 30 μm to 10 mm and 8 degrees, and in the case of drums, it is cylindrical. The surface opposite to the side on which the magnetic layer is provided is a so-called back coat.
'kcoat) may be used. Regarding backcoats, for example, U.S. Patent No. 2.804
, No. 401, No. 3,293,066, No. 3.61
7゜378, same No. 3,062,676, same No. 3,7
No. 34,772, No. 3,476.596, No. 2,
No. 643,048, No. 2.803,556, No. 2
, No. 887,462, No. 2.923゜642, 2.
99'7. No. '451, No. 3,007,892,
It is described in the specifications of the same No. 3,041,196, the same No. 3.115.420, the same No. 3.166.688, etc. Further, the form of the support may be tape, sheet, card, disk, drum, etc., and various materials are selected as necessary depending on the form. The surface-treated ferromagnetic powder binder, dispersant, lubricant, abrasive, antistatic agent, solvent, etc. according to the present invention are kneaded to form a magnetic paint. For mixing, the ferromagnetic powder and each of the above-mentioned components are fed into a kneading machine either simultaneously or individually one after another. For example, there is a method in which the ferromagnetic powder is added to a solution containing a mass dispersant and kneaded for a predetermined period of time, and then the remaining components are added and kneading is continued 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, Sankranta, 8 zegvar
i Attritor, high-speed impeller disperser, high-speed stone mill, high-speed impact mill, disperser uniter, high-speed mixer, homogenizer, ultrasonic disperser, etc. When the magnetic paint of the present invention is dispersed by these methods, it is extremely well dispersed, and when the dispersibility evaluation method as described in the examples is used, the number of aggregates when observed with an electron microscope is , which was much smaller than that of conventional magnetic paints.
Pa1nt Flow and Pigme by l'J
nt Dispersion (1964 John
published by Willey & 5ons). It is also described in U.S. Pat. No. 2,581,414 and U.S. Pat. No. 2,855,156. Coating methods for forming a magnetic layer by applying the magnetic paint onto a support include air doctor coating, blade coating, air knife coating, Swiss coat, impregnation coating, reverse roll coating, transfer roll coating, gravure coating, and kiss coating. , 1 coat of Cass,
Spray coating, etc. can be used, and other methods are also possible, and these are described in detail in "Coach Ink Engineering" (published by Asakura Shoten in 1972). The magnetic layer coated on the support by such a method is optionally subjected to a treatment for orienting the ferromagnetic powder according to the present invention in the layer, and then the formed magnetic layer is dried. Further, if necessary, the magnetic recording body of the present invention is manufactured by subjecting it to surface smoothing processing or cutting it into a desired shape. In this case, the orientation magnetic field is approximately 500 to 35
00 Gauss, the drying temperature is preferably about 50 to 100°C, and the drying time is preferably about 3 to 10 minutes. The method of orienting the ferromagnetic powder according to the present invention may be the method described in the following patents. For example, U.S. Patent No. 1.949.840, U.S. Pat.
96゜359, same No. 3,001,891, same No. 3,
No. 172,776, No. 3,416,949, No. 3
．． Specifications of No. 473.960, No. 3,681゜138, Japanese Patent Publication No. 32-3427, No. 39-28368, No. 40-23624, No. 40-23625, No. 4
No. 1-13181, No. 48-13043, No. 48-3
These include various publications such as No. 9722. Margin below (e) Effects of the invention: The magnetic recording medium according to the present invention produced as described above has extremely good wear resistance compared to conventional ones,
It also had excellent storage stability. In addition, the magnetic recording medium according to the present invention has an SA ratio (signal-to-noise ratio) that is improved to d] compared to that of conventional magnetic recording media, and can obtain higher reproduction output than conventional magnetic recording media. I was able to do that. Therefore, the magnetic recording medium of the present invention showed excellent performance even in high-density recording. (f) Examples: Hereinafter, the present invention will be specifically described based on Examples and Comparative Examples. However, in the examples below, the term "part 1" represents "-parts by weight," and the terms "audio tape" and "pideotape" are both concepts expressed in the term "magnetic recording medium." included in Examples 1 to 12 ■Pretreatment Ferromagnetic powder 1 listed in Table 3 below, Flats 1 to A12
00 copies, respectively, about lXl0-' Table-3, /1
Basic electrolyte water bath 1 published in column 3 of 61-AI2
In addition to the looo portion, it was dispersed using a sand grinder. Below is the margin table-3.The thus obtained f-koi-3, /161~. 4612 3rd
To the basic electrolyte water bath solution containing ferromagnetic powder listed in the column, add 100 parts of a 5% water bath solution of a cationic surfactant listed in the third column of Table 4, which will be described later, according to the present invention.
After mixing and dispersing each again, the resulting dispersion was filtered, naturally dried, and then dried under reduced pressure.
16 (12) was obtained. ■Post-treatment Surface-treated ferromagnetic powder that has undergone the above treatment (pre-treatment)/
Using 16(1) to A(12), [Composition] Surface-treated ferromagnetic powder 75 parts Partially hydrolyzed vinyl chloride-vinyl acetate copolymer 7.5 parts IS Polyurethane 7.5 parts Silicone oil 15 parts Methyl ethyl keto 7 70 toluene
60 parts cyclohexane
5 parts of the composition are placed in a ball mill;
After thorough mixing and dispersion, 3 parts of tolylene diisocyanate is added and mixed uniformly. While applying a magnetic field to one side of a 15 μm thick polyethylene terephthalate film,
After coating to a dry film thickness of 5μ, the resulting wide sample was supercalendered and slit into a 7n wide sample. Powdered eggplant (1) ~
, % (12), tapes 1 to 12, respectively. Table 4 Examples 13 to 20 ■Pretreatment 100 parts of the ferromagnetic powder described above in Table 3, AI 3 to 20, respectively, were added to approximately In addition to 1000 parts of the basic electrolyte bath solution listed in the column, add a basic electrolyte aqueous solution containing ferromagnetic powder listed in Table 3, Δ613 to /1620, which was obtained by dispersing it with a sand grinder. For,
Add 100 parts of a 5% methanol solution of the cationic surfactant listed in Column 3 of Hikari-4, A (13) to Fu (20), mix and disperse again, and filter the resulting dispersion. After drying, dry under reduced pressure to form a batter = 4, A (13), which will be described later.
～A surface-treated ferromagnetic powder listed in the third column of Δ6 (2) was obtained. ■ Post-treatment Surface-treated ferromagnetic powder (13) after the above treatment was obtained～
/16. Using (20), [Composition: Surface-treated ferromagnetic powder: Partially hydrolyzed vinyl chloride-vinyl acetate copolymer: 7.5 IS]
Polyurethane 7.5 parts 1 part Silicone oil 1 part Methyl ethyl ketone 70 members (S Toluene 60 parts Cyclohexalone 5 parts The composition was placed in a ball mill, thoroughly mixed and dispersed, and then 3 parts of tolylene diisocyanate was added and mixed uniformly. The thus obtained magnetic paint was applied to one side of a polyethylene terephthalate film with a film thickness of 15 μm while applying ffljM so that the dry film thickness became 5 μm. Thereafter, the wide sample obtained was supercalendered. The narrow-face treated ferromagnetic powder A (13
) ~16 (20) K response, cheap 13~2
Set to 0. Examples 21 to 43 ■ Ferromagnetic powder 100 listed in Pretreatment Table-3,421 to Atsushi 43
Each section is about 1 x 104 prescribed Table-3, Conditions 21-4
In addition to 1000 parts of the basic electrolyte water bath solution described in the third column of Section 3, the mixture was dispersed using a sand grinder. The base a electrolytes 1621 to 010 containing ferromagnetic powder listed in the third column of Table 3, Ita 21 to 43, thus obtained.
After adding 50 parts of % aqueous solution and mixing and dispersing each again,
After adding 1000 parts of the hydrophobic organic solvent listed in Table 5, column 4 of lines /%21 to /l643 and dispersing again, embedded ferromagnetic powders Gallo (21) to A6 (43) were obtained. Table-5 ■Post-treatment Unwashed surface-treated ferromagnetic powder (21) that has been subjected to the treatment described in ■ above.
~A'(43)'t- [Composition] Surface-treated ferromagnetic powder 75 parts Partially hydrolyzed vinyl chloride-vinyl acetate copolymer 7.5 parts Polyurethane 7.5 parts Silicone oil 1.5 parts Methyl ether Ketone 70 parts toluene
60 parts cyclohexane
Place the 5-part composition in a ball mill;
After sufficiently mixing and dispersing, add 3 parts of tolylene diisocyanate and mix uniformly.(The magnetic paint obtained in this way is applied to one side of a polyethylene terephthalate film with a film thickness of 15μ while applying a magnetic field.
The coating was applied to a dry film thickness of 5 μm. Thereafter, the resulting wide sample was supercalendered to make a 12.65 rrm wide slit video tape, and each sample was stored using surface-treated ferromagnetic powder A (
Tapes 21 to 43 are selected according to 2υ to (43). Examples 44 to 49 ■ Pretreatment 100 parts of the ferromagnetic powder listed in Table 3, 44 to 49, No. 3, were added with about 1000 parts of a basic electrolyte water bath solution specified by I Table 3, washing 44 to waste 49 No. 3 @
Basic electrolyte water bath solution A4 containing ferromagnetic powder published in
4 to A49, and the five cationic surfactants listed in Table 5, Bian (44) to Bian (49), No. 3@. After adding 1000 parts of the hydrophobic organic solvent listed in column 4 and dispersing again, the aqueous layer is removed and the organic layer is taken out.
)~/l6 (49) [Composition] Surface-treated ferromagnetic powder 75 parts Partially hydrolyzed vinyl chloride-vinyl acetate copolymer 7.5 parts Polyurethane 7.5 parts Silicone oil 1.5 parts Methyl ethyl ketone 70 parts toluene
60 parts cyclohexane
Place the 5-part composition in a ball mill;
After mixing thoroughly, add 3 parts of tolylene diisocyanate and mix uniformly (while applying a magnetic field to one side of a polyethylene terephthalate film with a thickness of 15 μm,
The coating was applied to a dry film thickness of 5 μm. After that, the obtained wide sample f-+ was supercalendered and slit into 12.65+rm width.
Surface-treated ferromagnetic powder A (44
) to A (49), tapes 44 to 49 are used. Examples 50 to 72 ■ Pretreatment For the ferromagnetic powder-containing U basic electrolyte aqueous solutions y1621 to A43 described in Table 3 and 21 to 4643, respectively, the cationic surfactant listed in the third column of Table 5 was used. Add 50 ml of 10% water bath solution and mix and disperse again.
5 Add 1000 parts of the hydrophobic organic solvent listed in column 4, redisperse, remove the water layer, and prepare the dispersion of the surface-treated ferromagnetic powder (
50) to A (72) were obtained. ■ Post-treatment Next, the dispersion of the surface-treated ferromagnetic powder obtained by [Composition] Dispersion of surface-treated ferromagnetic powder according to the present invention 210 parts partially hydrolyzed vinyl chloride-acetic acid Vinyl copolymer 7.5
Put a composition of 1.5 parts of silicone oil and 7.5 parts of polyurethane into a ball mill, mix and disperse thoroughly, then add 3 parts of tolylene diisocyanate and mix uniformly to obtain a magnetic paint. This magnetic coating material was applied to one side of a polyethylene terephthalate film having a film thickness of 15 μm while applying an @ field to give a dry film thickness of 5 μm. The wide sample obtained in this manner was supercalendered and slit to a width of 12.65 rrm to produce a videotape.The tape was then treated with ferromagnetic powders 421 to 4 containing the tape, respectively.
The tapes are 50 to 72 depending on the type of tape 3. Examples 73 to 78 ■Pretreatment Basic electrolyte water bath solution containing ferromagnetic powder/1644 to A49 listed in Table 3 and Waste 44 to 49 was treated with cationic surfactant listed in column 3 of Table 5, respectively. 5 parts of agent and 5 parts of batter
After adding 1000 parts of the hydrophobic organic solvent listed in Section 4s and redispersing, the water layer was removed, and after dispersing the surface-treated ferromagnetic powder, A
(73)-4 (78) was obtained. ■ Post-treatment After completing the above steps, the resulting dispersion of surface-treated ferromagnetic powder is concentrated and dehydrated using a molecular sieve.The molecular sieve is removed, and the surface-treated ferromagnetic powder and [
After adjusting the ratio of methyl isopropyl ketone, toluene, and cyclohexane by concentrating or adding a solvent to the following ratio, [Composition] Dispersion of surface-treated ferromagnetic powder according to the present invention
Partially hydrolyzed M vinyl chloride-vinyl acetate copolymer 75
A composition consisting of 1.5 parts silicone oil and 7.5 parts polyurethane was placed in a ball mill, thoroughly mixed and dispersed, and then 3 parts of tolylene diisocyanate were added and mixed uniformly to obtain a magnetic coating f-1-. This magnetic paint was applied to one side of a polyethylene terephthalate film having a film thickness of 15 μm while applying a magnetic field to give a dry film thickness of 5 μm. In this way, 1 muta wide sample #+ is supercalendered -, ]' 2.65■
It was slit into widths and a videotape fff was made. 44 ferromagnetic powders containing this tape, respectively.
- Tapes 73 to 7 were used depending on the type of A49. Comparative Example 1 ■ Pretreatment In 1000 parts of pure water, 100 parts of Co Miyagi Fe, 04 powder
After dispersing 50 parts of a 10% sodium dodecyl sulfate water bath solution, the dispersion was stirred again, and the dispersion was then filtered, air-dried, and then dried under reduced pressure to obtain a surface-treated ferromagnetic powder. This is referred to as surface-treated ferromagnetic powder comparative sample (1). (In this comparative example, the surface-treated ferromagnetic powder was simply dispersed in pure water without being dispersed in an electrolyte water bath.) ■ Post-treatment Next, the surface-treated ferromagnetic powder comparative example sample (1
) was used to prepare magnetic coating #+ having the following composition. [Composition] Comparative example sample (1) ・75
Partially hydrolyzed vinyl chloride-vinyl acetate copolymer 7.
5 Polyurethane 75 parts Silicone oil 1.5 parts Methyl Ethyl Keto 7 70 parts Toluene
60 parts cyclohexanone
The 5-part amphoteric paint is prepared by placing the above composition in a ball mill, thoroughly mixing and dispersing it, then adding 3 parts of tolylene diincyanate and mixing uniformly. The thus obtained magnetic paint was applied to one side of a 15μ thick polyethylene terephthalate film while applying a magnetic field.
The coating was applied so that the dry film thickness was 5μ. Thereafter, the obtained wide sample was supercalendered and slit into a width of 12.65 rrm to obtain a videotape as a sample tape. Comparative Example 2 ■Pre-treatment 1000 parts of a toluene solution containing 5 parts of lecithin (conventionally used dispersant) containing CO in e=04 powder 1
After dispersing 00 parts, it was filtered, air-dried, and then dried under reduced pressure to obtain a surface-treated ferromagnetic powder. This is referred to as surface-treated ferromagnetic powder comparative sample (2). ■ Compare the videotape of the sample obtained after post-processing with tape 2
shall be. Comparative Example 3 ■ Pretreatment In 1000 parts of a toluene solution containing 5 parts of lecithin (conventionally used dispersant), a magnetic alloy (Fe-Co-N
i) After dispersing 100 parts of the powder, it was filtered and subjected to the above pre-treatment. Surface-treated ferromagnetic powder Comparative Sample 3 was subjected to the same post-treatment as in Comparative Example 1. The sample videotape is referred to as Comparison Tape 3. Comparative Examples 4-5 Untreated Co-containing Fe50. The powders were subjected to the same post-treatment as in Comparative Example 1, and the sample videotapes were Comparative Tapes 4, 5 and 1, respectively. Next, the measurement results of the tape performance of each of the tapes 1 to 78 and comparative tapes 1 to 5 obtained in Examples 1 to 78 and Comparative Examples 1 to 5 are shown in Table 6 below. However, tape performance was measured in terms of squareness ratio, playback output, shedding ratio, drag resistance, and adhesiveness. Further, the measurement criteria for the squareness ratio, reproduction output, SA ratio, abrasion resistance, and tackiness are as follows. (a) Squareness ratio: Residual magnetization Br and saturation magnetization Bm were measured. (b) Using a VTR deck for measuring crab IIIF skewer force for reproduction, the operating power up to 4 Mz was measured and expressed as a relative value when the output of comparison tape/164 was set to 0. (c) S/N ratio: Co-containing Fe, 04 was used as the ferromagnetic powder. Regarding the sample tape), set the value of the tape of comparison example 4 to 0.
Regarding the sample tape with dT3 and magnetic alloy (Fe-Co-Ni) as the ferromagnetic powder, comparison = value 1 of the tape of Example 5.
It is shown as a relative value when it is set to 0clB. Note that * is marked for those whose ferromagnetic material is a magnetic alloy (Fe-Co-Ni). (d) Abrasion resistance: Using a simulated head, a 5 m long tape was heated at 7 m/sec.
The tape surface was repeatedly slid back and forth at a speed of , and the surface of the tape was then measured visually and using a microscope. (In Table 6, those with high abrasion resistance are marked with ◎, those with average wear resistance are marked with ○, and those with poor wear resistance are marked with Judgment was made based on the occurrence of stickiness of the island. (In Table 6, (the case where pecking does not occur is indicated by ○, and the case where pecking occurs is indicated by x). The method uses a surface-treated ferromagnetic powder that is simply dispersed in a basic electrolyte solution and then subjected to angular dispersion treatment with a cationic surfactant having a coating structure according to the general formula (1) or 011. (Dage 1 to Tape 20), and also when the hydrophobic organic solvent according to the present invention was added to these dispersions to transfer the ferromagnetic powder to the organic layer, and then the surface-treated ferromagnetic powder was taken out. (Tape 21 to Tape 78), it is clear that the magnetic recording media containing the surface-treated ferromagnetic powder obtained by the conventional method have far superior performance. The magnetic recording media shown above all show the results for video tapes, but audio tapes obtained through the same processing as in Examples 1 to 78 were also tested for squareness ratio, playback output, and wear resistance. sex,
Once it was found that the storage stability was good, in order to investigate the surface properties and dispersibility of the surface-treated ferromagnetic powders after the pretreatment process of Examples 1 to 78 and Comparative Examples 1 to 5, these The degree of hydrophobicity and sedimentation rate of the ferromagnetic powder of the surface treatment agent were measured and the results are shown in Table 7. The degree of hydrophobization is determined by adding each ferromagnetic powder to a solution with different mixing ratios of pure water and methanol.If the ferromagnetic powder floats in the solution without getting wet,
/cm), the surface energy of the ferromagnetic powder (dyn
If the ferromagnetic powder gets wet with the solution and disperses or precipitates, this is determined from the fact that the surface energy of the Tonic 11 powder is larger than the surface tension of the solution. The sedimentation speed is determined by adding 1 g of ferromagnetic powder to a sedimentation tube (inner volume: 3 Qn
-t', inner diameter: 10m → Add n-hexane and 30r
nJ, all the ferromagnetic powder dispersion solutions were shaken at the same degree for 1 minute, left to stand, and 24 hours later, the height from the solution surface to the suspension interface was measured to determine the sedimentation rate. Margin Table 7 below From the results in Table 7, it can be seen that the degree of hydrophobicity and sedimentation rate of the surface-treated ferromagnetic powder contained in the ferromagnetic layer of the magnetic recording medium according to the present invention are higher than those of the conventional surface-treated ferromagnetic powder. is also small, indicating excellent dispersibility. In addition, the magnetic paints used in producing the magnetic recording media according to the present invention in Examples 1 to 78 and the test f8+ in Comparative Examples 1 to 5
Using an applicator, each of the comparative magnetic coatings used in the preparation of the magnetic coating '#+ was applied to a glass plate with a thickness of 60 μm (when wet), and the dispersion process was observed using a microscope. The samples using the magnetic paint had a lot of aggregates, whereas the samples using the magnetic paint used in Examples 1 to 78 were uniformly dispersed and had very few aggregates. Procedural amendment (voluntary) 1. Display of 4+ cases 1982 Patent w+ No. 4008 3 Person making the amendment jj Relationship between cases 7 Patent applicant name (Name) (127) Konishiroku Photo Industry Co., Ltd. (1 ) "Binder 10-4" on page 46, lines 4-5 of the specification
00 parts by weight, preferably 30 to 100 parts by weight...'' was replaced with ``5 to 400 parts by weight, preferably 10 parts by weight of the binder.
~200 heavy view section...'' (2) Details of the chopsticks box, page 48, line 5 [...Binding agent] 00.
``...'' is replaced with ``...Ferromagnetic powder 100...''
shall be. (3) In the third line from the bottom of page 48 of the specification, the statement "...binder 100..." was replaced with "...ferromagnetic powder 100..."
0...'' (4) On page 49, line 15 of the statement box, “...Binder 100
..." is replaced with "...ferromagnetic powder]00...
”. The above formal formalities (spontaneous) [ [ 1, -! Display of J+ items 1982 Patent f1 No. 4008-3, Relationship with the person making the amendment ('l) Patent applicant, 1. Address: 1-26-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo
Title Name <q slip: + (12t) Konishi Roku Photo Industry Co., Ltd. 6 Number of inventions increased due to sleeve correction None 7, Subject of amendment] 1] Scope of claims in specification oath (attached) Correct as shown. ]2] The detailed description of the invention column in the specification is amended as follows. (1) The phrase "...with a surfactant..." on page 8, lines 16-17 of the specification box is changed to "...with a surfactant...". (2) The statement "With a surfactant..." on page 9, line 4 of the specification is changed to "With a surfactant...". (3) Add the following sentence between lines 16 and 17 on page 10 of the specification box. The ferromagnetic powder that can be used in the present invention includes CO-coated r
"z 03 , Co-coated Fes 04 , r-Fet
03,) e. Oa, Co-containing r-Fe, 03, Co-containing Fe3
In addition to oxide-based ferromagnetic powders such as O4 and Cr0t, metal-based ferromagnetic powders can also be used. Examples of metal-based ferromagnetic powders include metal-based ferromagnetic powders of simple metals such as Fe, Ni, C'o, and Cr, and Fe-C0-N.
i, F”e-A7. MnB i, Fe-A
7-P, Fe-Co-Ni-Cr. F e -N 1-Zn, F”e-Co-N i
-P, Fe -N i, Co -N i -P
. Ni-Co, Co-P, Fe-Mn-Zn-Fe-N
i -Mn, P'e -Ni-Cr -P, Fe-
Metal-based ferromagnetic powders of alloys such as JJi-Co-Zn are praised, and additives such as Mg, Mn, Si
, P, Cu, AA! Metal-based ferromagnetic powder containing elements and compounds thereof may also be used. (4) “20rrLl~50” on page 23, line 13 of the specification
0m1..." description r20m7~5,000-
7..." (5) The structural formula of the compound in box 70 in Table 1 on page 23 of the specification is as follows. (6) The structural formula of compound 32 in Table 2 on page 28 of the specification is as follows. The structural formula of the compound is as follows: Cl-1s%CH,-)-NH-(EH,-4jJJ-
CH, -N[(, o2 CH3CO0H (8) The structural formula of the compound of K-38 in Table 2 on page 29 of the specification is as follows. CH,C00H
J and [Ru. 00) Statement box page 35, line 16, “- dispersion treatment liquid...
・'' is changed to ``this dispersion treatment liquid...''. αυ On page 23, line 11 of the specification, “...dry,...
・" is changed to ``...dehydrated,...''. Above (Attachment) Claims (1) In a magnetic recording medium comprising a ferromagnetic layer containing a surface-treated ferromagnetic powder provided on a support, the surface-treated ferromagnetic powder is dissolved in a basic electrolyte solution. A magnetic recording medium obtained by dispersing ferromagnetic powder therein and then redispersing it with an interfacial agent having a structure represented by the following general formula (I) or (IT). . The general formulas (I) and (n) are respectively: ■' -N -R2m mA (■)
t3 is represented by Substituted amino group and/or substituted or unsubstituted 1
or a divalent aryl group) or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms (which may be a heterocyclic compound; (which may have a saturated or unsaturated substituted or unsubstituted alkyl group and/or a substituted amino group having 1 to 24 carbon atoms); R4 represents a saturated or unsaturated substituted or unsubstituted alkyl group or a water bulky atom;
represents a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, n is a positive integer of O to 4, Q represents a nitrogen atom or a carbon atom, and Qk represents a saturated or unsubstituted alkyl group. It represents a 6-membered ring, A represents an organic or inorganic acid, and m represents a positive real number. (2) In a magnetic recording medium in which a ferromagnetic layer containing a surface-treated ferromagnetic powder is provided on a support, the surface-treated ferromagnetic powder is obtained by dispersing the ferromagnetic powder in a basic electrolyte solution. Afterwards, the ferromagnetic powder is re-dispersed with a surfactant having a structure represented by the following general formula CI) or (TI), and a hydrophobic organic solvent is added to the dispersion treatment liquid to transfer the ferromagnetic powder to the polishing layer. A magnetic recording medium characterized by being However, the general formulas (1) and (TI) are respectively R'-N -几-m人
(I) 3 is represented by or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms. aryl group (which may be a heterocyclic compound, and a saturated or unsaturated substituted or unsubstituted alkyl group having 1 to 24 carbon atoms and/or a substituted amino group as the above-mentioned substituent) 2 and R3 each represent a saturated or unsaturated (g-substituted or unsubstituted alkyl group or a water bulky atom) having 1 to 20 carbon atoms, 'fL4 is a carbon atom represents a substituted or unsubstituted alkyl group having from 1 to 10 atoms, n is a positive integer of O to 4, l-ζ\Q represents a nitrogen atom or a carbon atom, and 5 or saturated with QN It represents a 6-membered ring, human represents an organic or inorganic acid, and m represents a positive real number.

Claims (2)

[Claims] (1) In a magnetic recording medium in which a ferromagnetic layer containing a surface-treated ferromagnetic powder is provided on a support, the surface-treated ferromagnetic powder is formed by disposing the ferromagnetic powder in a basic electrolyte solution. After dispersing, the following general formula (I) or (II)
A magnetic recording medium characterized in that it is obtained by redispersion treatment with an interfacial agent having a structure represented by: The general formulas (I) and (It) are respectively represented by R1-N -R2-mA (1)3 and R1 is a saturated or unsaturated group having 1 to 30 carbon atoms. Alkyl group (which may be linear or branched, may be a cycloalkyl group, and may have a substituted amino group and/or one or two substituted or unsubstituted aryl groups as a substituent) ) or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms (which may be a heterocyclic compound; the above substituent may be a saturated or unsaturated aryl group having 1 to 24 carbon atoms); B2 and R3 each represent a saturated or unsaturated substituted or unsubstituted alkyl group having 1 to 20 carbon atoms; represents a group or a hydrogen atom, R4 represents a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, n is a positive integer of 0 to 4, and Q represents a nitrogen atom or a carbon atom. The expression Q represents a saturated 5- or 6-membered acid, human represents an organic or inorganic acid, and m represents a positive real number. (2) In a magnetic recording medium in which a ferromagnetic layer containing a surface-treated ferromagnetic powder is provided on a support, the surface-treated ferromagnetic powder is obtained by dispersing the ferromagnetic powder in a basic electrolyte solution. After that, redispersion treatment is performed using a surfactant having a structure represented by the following general formula (1) or (II), and a hydrophobic organic solvent is further added to the fraction treatment liquid to transfer the ferromagnetic powder to the organic layer. A magnetic recording medium characterized by being a magnetic recording medium. t'xL general formula (
1) and (n) are respectively represented by R1-N-r-mA (1)s and (R")n, and R1 is a saturated or unsaturated group having 1 to 30 carbon atoms. Alkyl group (which may be linear or branched, or may be a cycloalkyl group, having a substituted amino group and/or a substituted or unsubstituted ail group as a substituent) ) or a substituted or unsubstituted aryl group having 6 to 30 carbon atoms (which may be a heterocyclic compound, and the above substituent may have 1 to 24 carbon atoms) (which may have a saturated or unsaturated substituted or unsubstituted alkyl group and/or a substituted amine group), and Hj and R1 each represent a saturated or unsaturated substituted or represents an unsubstituted alkyl group or a hydrogen atom, R" represents a substituted or unsubstituted alkyl group having 1 to 10 carbon atoms, n is a positive integer of O to 4, and Q is a nitrogen atom or represents a carbon atom, represents a 5- or 6-negative ring saturated by Q''N, represents an organic or inorganic acid, and m represents a positive real number.