JPH01271912A - Resin composition and magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve polishability, durability and traveling property by using a resin having specific polar groups. CONSTITUTION:At least one kind of the polar groups selected from the group expressed by general formula I are incorporated into the resin used for the magnetic recording medium. In formula, M denotes a hydrogen atom, lithium, sodium or potassium; M<1> and M<2> respectively denote a hydrogen atom, lithium, sodium, potassium, and alkyl group; M<1> and M<2> may be the same as or different from each other. A packing material is dispersed in a short time at a high degree of dispersion in this resin and the stable dispersibility is obtd. even after the dispersion.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a resin composition and a magnetic recording medium. More specifically, the present invention relates to a resin composite formed by uniformly dispersing an inorganic filler in a resin having a polar group, and a magnetic recording medium having excellent electromagnetic characteristics and durability.

[Problem 8 to be solved by the prior art and the invention] Conventionally, resin compositions consisting of a resin and an inorganic filler have been effectively used for various purposes.

For example, a resin composition consisting of a resin and an inorganic filler,
It is used for cleaning tapes for magnetic heads of VTRs, tape recorders, etc., leader tapes for cassette tapes, etc., and hard tapes made of various materials.

Usually, this resin composition is made by dispersing an inorganic filler as an abrasive in a resin such as a urethane resin or a cellulose resin.

However, in this resin composition IR, the inorganic filler is not dispersed sufficiently uniformly in the resin, and the dispersion is slow, and the stability of the dispersion state after dispersion is also poor. The problem is that it is not possible to obtain a uniformly dispersed filler.

Therefore, there is a problem that the polishing properties, durability, runnability, etc. of the cleaning tapes, leader tapes, polishing tapes, etc. described above are inferior.

On the other hand, in magnetic recording media used in video tapes, audio tapes, etc., in order to improve running properties and electromagnetic conversion characteristics, inorganic fillers are added to the magnetic layer as an abrasive. There is.

Generally, in the production of conventional magnetic recording media, a magnetic paint is prepared by simultaneously mixing and dispersing magnetic powder and an inorganic filler.

However, with this magnetic paint, it is not possible to obtain one in which the inorganic filler is uniformly dispersed.

A magnetic recording medium using this magnetic paint has problems in that the inorganic filler in the magnetic layer is not uniformly dispersed, resulting in poor durability and poor electromagnetic conversion characteristics.

It has also been proposed to prepare a magnetic paint by mixing and dispersing an inorganic filler in a resin such as a urethane resin or a cellulose resin, and then mixing and dispersing the filler with magnetic powder.

However, even in the magnetic layer of the magnetic recording medium obtained in this way, there is a problem that the inorganic filler is not sufficiently uniformly dispersed.

The present invention has been made based on the above circumstances.

That is, one object of the present invention is to provide a resin composition in which an inorganic filler is uniformly dispersed in a resin.

A further object of the present invention is to provide a magnetic recording medium that has an inorganic filler uniformly dispersed in a magnetic layer and has excellent electromagnetic conversion characteristics and durability.

[Means and effects for solving the above problem] The invention according to claim 1 for solving the above problem is a resin composition comprising a resin having a polar group and an inorganic filler.

The polar group of the resin having the polar group.

-302M, -0SO3M, -COOM.

OM' and -P=00M2 (where M represents a hydrogen atom, lithium, sodium or potassium, and Ml and M2 each represent a hydrogen atom, lithium, sodium, potassium or an alkyl group) , Ml and M2 may be the same or different.) The resin composition is characterized in that it is at least one type of polar group selected from the group consisting of the following.

The invention according to claim 2 is a magnetic recording medium provided with a magnetic layer containing the resin composition according to claim 1.

Hereinafter, the resin composition and magnetic recording medium of the present invention will be explained in detail.

Ru.

11 Resin Composition 11 The resin composition in the present invention is a resin having the above-mentioned polar group [hereinafter sometimes referred to as resin (A). ] and an inorganic filler.

-Resin (A) - The resin (A) has polar groups -303M, -0302M, -COOM, OM'' and -P;00M'' (wherein M is a hydrogen atom, lithium, sodium or (Ml and M2 each represent a hydrogen atom, lithium, sodium, potassium, or an alkyl group; Ml and M2 may be rotated or may be different.) It has at least one type of polar group.

Specifically, examples include resins obtained by introducing the polar groups into polyester resins, polyethylene resins, vinyl chloride resins, and the like.

These resins can be obtained by various methods. For example, polyester resins containing sulfonic acid metal bases are
It can be obtained by using a dicarboxylic acid containing a sulfonate metal base as part of the dicarboxylic acid component and condensing this with a dicarboxylic acid not having a sulfonate metal base together with a diol.

The polyurethane resin containing a sulfonic acid metal base is made of a dicarboxylic acid containing a sulfonate metal base, a dicarboxylic acid containing no sulfonate metal base, and a diol, which are the starting materials for the polyester containing a sulfonate metal base. Using various compounds and diisocyanate,
It can be obtained by li1 combination reaction and addition reaction.

Furthermore, a method of modifying a polyester resin, polyurethane resin, or vinyl chloride resin to introduce a polar group is also considered.

That is, with these resins, e.g.

C-CHt CH2S Ox M, CI C82CHt OS 02 M, 0 sentences-CH2
Contains the above polar group and chlorine in the molecule, such as CHt COOM, OM' C-CH, -P=0 ■ OM" (M, M' and M2 have the same meanings as above) This method involves condensing and introducing a compound with a dehydrochloric acid reaction.

The carboxylic acid components used to obtain polyester resins and polyurethane resins include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, and 1,5-naphthalic acid; p-oxybenzoic acid, p-(
Aromatic oxycarboxylic acids such as (hydroxyethoxy)benzoic acid: succinic acid, adipic acid, azelaic acid, sebacic acid.

Examples include aliphatic dicarboxylic acids such as dodecanedicarboxylic acid, tri- and tetracarboxylic acids such as trimellitic acid, trimesic acid, and pyromellitic acid.

Among these, terephthalic acid is preferred.

These are isophthalic acid, adipic acid, and sebacic acid.

Examples of the dicarboxylic acid component containing the sulfonic acid metal base include 5-sodium sulfoisophthalic acid,
Examples include 5-potassium sulfoisophthalate, 2-sodium sulfoterephthalate, and 2-potassium sulfoterephthalate.

Examples of the diol component include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-bentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, and dipropylene diol. recall, 2
, 2.4-trimethyl-1,3-bentanediol,
1,4-Cyclohexane dimetatool, ethylene oxide adduct of bisphenol A, hydrogenated bisphenol A
ethylene oxide adduct, polyethylene glycol,
Examples include polypropylene glycol and polytetramethylene glycol. Also, trimethylolethane,
Tri- and/or tetraols such as trimethylolpropane, glycerin, and pentaerythritol can also be used in combination.

Examples of the incyanate component used to obtain the polyurethane resin include 2,4-)-lylene diisocyanate, 2,6-tolylene diisocyanate, P
-Phenylene diisocyanate, diphenylmethane diisocyanate, m-phenylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, 4,4'-diisocyanate-
Diphenyl ether, l,3-naphthalene diisocyanate, p-xylylene diisocyanate, m-xylylene diisocyanate, 1,3-diisocyanatemethylcyclohexane, 1,4-diisocyanatemethylcyclohexane, 4.4"-diisocyanatedicyclohexane, 4.4" -Diisocyanate dicyclohexylmethane, isophorone diisocyanate and the like.

When modifying a vinyl chloride resin to introduce a sulfonic acid metal base, examples of the vinyl chloride resin include vinyl chloride-vinyl acetate-vinyl alcohol copolymer, vinyl chloride-vinyl propionate-vinyl alcohol copolymer, Vinyl chloride-vinyl acetate-vinyl maleate-vinyl alcohol copolymer, vinyl chloride-propionic acid and vinyl maleate-vinyl alcohol copolymer, etc. can be used.

Vinyl alcohol OH contained in these copolymers
group and the aforementioned C1-CH2CHaSOJ.

The chlorine of the chlorine-containing sulfonic acid metal salt such as C1-CHfflCll, 030211, etc. is removed by dimethylformamide,
Amine salts such as pyridine, picoline, triethylamine, etc. in polar solvents such as dimethyl sulfoxide.

A method of carrying out a dehydrochlorination reaction in the presence of a dehydrochlorination agent such as an epoxy compound such as ethylene oxide or propylene oxide can be suitably used.

The molecular weight of the resin (A) is 1, usually 1,000 to 2.
It is 0.000. When this molecular weight exceeds 20,000.

The viscosity of the paint may be too high to be practical. On the other hand, if the molecular weight is less than 1,000, the durability of the coating film will be low and unreacted substances may bleed onto the surface of the magnetic layer, making it difficult to use.

Further, the resin (A) preferably has a molecular weight of 1 (per 1 polar group) in the range of 200 to 60,000.
If the molecular weight per polar group is less than 200, the hydrophilicity of the resin will be too strong, resulting in a decrease in solubility in solvents, compatibility with other resins in the binder, and moisture resistance of the magnetic layer. I may invite you. On the other hand, the molecular weight per polar group is 60,00
If it exceeds 0, the dispersibility may not be sufficiently improved.

-Inorganic filler- As the inorganic filler, non-magnetic powder is usually used.

Examples of the non-magnetic powder include silicon dioxide, titanium oxide, aluminum oxide, chromium oxide, zinc oxide, tin oxide, α-Fe, O, etc., such as silicon, titanium, aluminum, zinc, chromium, tin, and molybdenum. Oxides such as molybdenum dioxide; Carbides such as silicon carbide; Nitrides such as boron nitride; Fluorides such as zinc fluoride; Sulfates such as barium sulfate and calcium sulfate; Carbonates such as magnesium carbonate; Carbon black; Graphite: Talc: Examples include kaolin. Preferred are silicon oxide, chromium oxide, and α-Fear3. these are,
They may be used alone or in combination of two or more.

It is preferable that the average particle size of the inorganic filler is 0.2 to 0.5 pm.

The shape of the inorganic filler is not particularly limited, and examples include flat, acicular, spherical, and fibrous shapes.

1. Manufacturing method 1. The resin composition is obtained by blending the resin (A) and the inorganic filler.

The resin (A) and the 1IAa in the resin composition
l Filler tonneau blending ratio 1.1.2/98 to 4G/60
It is preferably within the range of 5195 to 30/fi.
Preferably, it is within the range of 70.

The resin composition may contain a colorant, a lubricant, and a surfactant as long as they do not impair the purpose of the present invention.

It may also contain other components such as a silane coupling agent.

The resin composition may be prepared by, for example, dissolving the resin (A) and the inorganic filler in a solvent [hereinafter sometimes referred to as (A)]. ] can be obtained by mixing and dispersing.

Examples of the solvent (A) include ketone solvents such as acetone, methyl ethyl ketone, and cyclohexanone; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, propyl acetate, and ethylene glycol monoacetate; benzene, toluene, Aromatic solvents such as xylene; Alcohol solvents such as methanol, ethanol, propatool, and butanol; Ether solvents such as diethylene glycol dimethyl ether, 2-ethoxyethanol, tetrahydrofuran, and dioxane; methylene chlorite, ethylene chloride, and tetrachloride. Examples include carbon, chloroform, dichlorobenzene, halogenated hydrocarbon solvents such as trichlorotrifluoroethane, and the like.

(Mixing and dispersing method) The above-mentioned resin composition components can be mixed and dispersed by a conventional method.

When mixing and dispersing the resin composition components, there is no particular restriction on the order in which the resin composition components are added, and each component can be added and mixed and dispersed according to a conventional method.

A known mixing and dispersing device can be used for mixing and dispersing, and examples of such mixing and dispersing devices include a two-roll mill, a Miki roll mill, a ball mill, a pebble mill, a side talinder, and a Sqegva mill.
ri attritor, high speed impeller disperser, high speed stone mill, high speed impact mill, Disper Kneader-1 high speed mixer, homogenizer and ultrasonic disperser.

11. Magnetic Recording Medium 11. The magnetic recording medium of the present invention is provided with a magnetic layer containing the resin composition.

A serious magnetic layer is usually provided on a non-magnetic support.

- Non-magnetic support - Materials forming the non-magnetic support include, for example, polyesters such as polyethylene terephthalate and polyethylene-2,6-naphthalate; polyolefins such as polypropylene; and cellulose derivatives such as cellulose triacetate and cellulose diacetate. ; Examples include plastics such as polycarbonate. Furthermore, Cu.

A1. Metals such as Zn, glass, and various ceramics such as so-called fine ceramics (for example, boron nitride, silicon carbide, etc.) can also be used.

The form of the non-magnetic support is not particularly limited, and may include tape,
It may be a sheet, card, disk, drum, etc., and various materials can be selected and used depending on the form and as necessary.

The thickness of the non-magnetic support, when in the form of a tape or sheet, is usually within the range of 3 to 100 g, m, preferably within the range of 5 to 50 uLm. Moreover, in the case of a disk shape or a cart shape, it is usually within the range of 30 to +00 gm. Furthermore, in the case of a drum shape, it can be made into a cylindrical shape, etc., to correspond to the recorder used.

A back coat layer may be provided on the surface (W surface) of the nonmagnetic support on which no magnetic layer is provided for the purpose of improving running properties of the magnetic recording medium, preventing charging, preventing transfer, and the like.

In addition, on the surface of the non-magnetic support where the magnetic layer is provided, for the purpose of improving the adhesion between the magnetic layer and the non-magnetic support, etc.
Intermediate layers (eg adhesive layers) can also be provided.

One Magnetic Layer: The magnetic layer is a layer containing the resin composition and magnetic powder dispersed in a binder.

(Magnetic powder) The magnetic powder may be any material that can be used in ordinary magnetic recording media, such as iron oxide magnetic powder; oxide-based magnetic powder containing other components such as CO. ;
Fine powder of ferromagnetic metal such as Fe, Ni, Go; Fe
, Xi, Go, and other ferromagnetic alloy powders containing ferromagnetic metals and other components. These may be used alone or in combination of two or more.

(Binder) ■The single binder includes resins such as thermoplastic resins, thermosetting resins, reactive resins, electron beam curable resins, or mixtures thereof, which have been conventionally used in magnetic recording media. Hereinafter, it may be referred to as resin (B). ] can be used.

Examples of the thermoplastic resin include vinyl chloride-vinylacetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, and acrylic ester-vinylidene chloride copolymer. Polymer, methacrylic acid ester-vinylidene chloride copolymer, methacrylic acid ester-ethylene copolymer, urethane elastomer, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, acrylonitrile-butadiene copolymer, polyamide resin,
Polyvinyl butyral, cellulose derivative (cellulose acetate butyrate).

cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose, etc.),
Examples include styrene-butadiene copolymers, polyester resins, chlorovinyl ether acrylate copolymers, amino resins, and synthetic rubber-based thermoplastic resins. These may be used alone or in combination of two or more.

Serious thermosetting resins or reactive resins include, for example, phenolic resins, epoxy resins, polyurethane curable resins, urea resins, melamine resins, alkyd resins, silicone resins, acrylic reactive resins, high molecular weight polyester resins, and isocyanate prepolymers. mixtures of methacrylate copolymers and shiisocyanate prebolimers, mixtures of polyester polyols and polyisocyanates, urea formaldehyde resins, mixtures of low molecular weight glycols/high molecular weight diols/triphenylmethane triisocyanates, and polyamine resins. . These may be used alone or in combination of two or more.

Examples of the electron beam curable resin include unsaturated prepolymers such as maleic anhydride type, urethane acrylic type, epoxy acrylic type, polyester acrylic type, polyether acrylic type, polyurethane acrylic type, polyamide acrylic type; ether acrylic type; , urethane acrylic type, epoxy acrylic type, phosphate ester acrylic type, aryl type, and hydrocarbon type. These may be used alone or in combination of two or more.

In this invention, the resin (B) may be used as it is as a binder, but furthermore, a curing agent may be used together with the resin (B) to serve as a binder.

Examples of the curing agent include polyisocyanate compounds (eg, tolylene diisocyanate).

4.4'-diphenylmethane diisocyanate.

Naphthylene diisocyanate, hexamethylene diisocyanate, cyclohexane diisocyanate and adducts of these polyisocyanate compounds and trivalent polyols, pentamer of diisocyanate, adduct of 3 moles of tolylene diisocyanate and 1 mole of trimethylolpropane, metaxylylene diisocyanate Examples include an adduct of 3 moles of trimethylolpropane and 1 mole of trimethylolpropane, and a pentamer of tolylene diisocyanate.

These may be used alone or in combination of two or more.

(Magnetic Layer) The mixing ratio of the magnetic powder and the binder (including the hardening agent when the hardening agent is used) in the magnetic layer is usually 1 part by weight per 100 parts by weight of the magnetic powder. Binder 5
-200 parts by weight, preferably 10-100 parts by weight. If the amount of binder blended is too large, the blended amount of magnetic powder will be low and the recording density of the magnetic recording medium will be reduced. If it is too small, the strength of the magnetic layer will be reduced and the magnetic recording medium will be damaged. Driving durability may be reduced.

The resin composition contained in the magnetic layer is contained in the magnetic layer at a blending ratio of 3 to 20 parts by weight based on 100 parts by weight of the magnetic powder.

1. Manufacturing method 1. The magnetic recording medium of the present invention can be manufactured, for example, in the following manner.

(2) The magnetic layer forming components such as the magnetic powder, the binder, the resin composition, and other components are used as a solvent [hereinafter sometimes referred to as solvent (B). ] to obtain a magnetic paint.

(2) Applying the magnetic paint to the non-magnetic support and drying it.

In this way, the magnetic recording medium of the present invention can be manufactured.

Examples of the solvent (B) include those that can be used as the solvent (A).

(Mixing and dispersing method) The above-mentioned magnetic layer forming components can be mixed and dispersed by a conventional method.

When mixing and dispersing the magnetic layer form ia, there is no particular restriction on the order in which the magnetic layer forming components are added, and each component can be added and mixed and dispersed according to a conventional method. However, when a curing agent is used, it is preferable to add the curing agent immediately before applying the magnetic paint in order to prevent the curing reaction from proceeding due to the curing agent during mixing and dispersion.

Examples of the mixing and dispersing device used for mixing and dispersing include those similar to the mixing and dispersing device used for mixing and dispersing the resin composition components described above.

Note that a dispersant can be used to mix and disperse the components of the magnetic layer.

Examples of the dispersant include lecithin.

Examples include phosphoric acid esters, amine compounds, alkyl sulfates, fatty acid amides, higher alcohols, polyethylene oxides, sulfosuccinic acids, sulfosuccinic esters, and known surfactants.

(Coating method) 2 m2 of the magnetic paint (coating liquid for magnetic layer forming components) is coated onto a non-magnetic support by a known method.

Coating methods that can be used in the present invention include:
Examples include gravure roll coating, wire bar coating, doctor plate coating, reverse roll coating, dip coating, air knife coating, calendar coating, squeezing coating, kiss coating, fanting coating, and the like.

The dry thickness of the magnetic paint applied in this manner is usually within the range of 1 to 20 gm.

There are no particular restrictions on the drying method, and any conventional method can be used.

Then, if necessary, surface smoothing treatment is performed using a calender roll or the like.

[Example 7] Next, Example 7 of the invention and a comparative example will be shown to further specifically explain the present invention. In addition.

In the Examples and Comparative Examples described below.

"Parts" shall represent "parts by weight."

(Example 1) A paste was prepared by mixing and dispersing a resin composition having the composition shown below in 95 parts of cyclohexanone.

α-AJltOz [average particle size: 0.2ILm]
100 parts 5 parts polyurethane resin having a sodium sulfonate group Dispersion status after mixing each component; 10 g film thickness on a glass plate
The 60° specular reflectance (%) at each dispersion time was determined by applying the resin composition so that the distance was m.

The results are shown in Figure 1.

The obtained paste was applied and dried on a polyester base film having a thickness of 14 pm so that the thickness after drying was 3 p.m, thereby producing a tape L having a width of 0.5 inch.

The polishing force of this tape L was measured under the following conditions.

FIG. 4 is an explanatory diagram showing wear bars used in Examples 1 to 3 of the present invention and Comparative Examples 1 to 3.

FIG. 5 is a sectional view showing the relationship between the tape and the wear bar in measuring the polishing force in Examples 1 to 38 of the present invention and Comparative Examples 1 to 3.

l) A wear bar J shown in FIG. 4 as shown below was used.

Shape: square prism 4.5±0.31 squares, width 1Bmm or more, squareness 50#Lm or less.

Material: Zn022% by weight, N4011% by weight.

Fe, 0367% by weight [H4R2 manufactured by Sumitomo Special Metals] *There are no holes or protrusions smaller than IBm in the corner K used for measurement.

*The radius of the corner is 13Bm or less.

2) The test was carried out as shown in FIG. 5, and the following conditions were set.

B) Aspiration P: 8''' on one side Mouth) Zhang crab 100g C) Tablesbee) (: 100m D) Running length: 100m E) Using a microscope with a magnification of 300 times or more, measure 1/4 of the wear mark M.
Radiation N at positions 1/2, 3/4 was measured and averaged.

In this way, the wear width was determined.

Further, the condition of the worn surface was observed using a microscope with a magnification of 400 times. In addition, evaluation was performed in the following manner.

O: The worn surface is uniformly mirror-finished.

×: Deep scratches in the form of thin stripes are present on the worn surface.

The results are shown in Table 1.

(Comparative Example 1) The polyurethane resin having a sodium sulfonate group used in Example 1 was replaced with a polyurethane resin having no polar group [
The same procedure as in Example 1 was carried out except that Nippon Polyurethane Co., Ltd. To2co01] was used instead.

The results are shown in FIG. 1 and Table 1.

(Example 2) Example! α-^1*Os'E average particle size used in: 0.2
fiLm], CrtQ3[average particle size: 0.3p
The same procedure as in Example 1 was carried out except that the volume was changed to ml.

The results are shown in FIG. 2 and Table 1.

(Comparative Example 2) The polyurethane resin having a sodium sulfonate group used in Example 2 was replaced with a polyurethane resin having no polar group [
Three samples were completed in the same manner as in Example 2 except that N-43011 manufactured by Nippon Polyurethane Co., Ltd. was used instead.

The results are shown in FIG. 2 and Table 1.

(Example 3) α-AJ1.03 [average particle size: 0.2] used in Example 1
#Lml, a-FezOs [average particle size: 0.3i
The same procedure as in Example 1 was performed except that Lm] was used.

The results are shown in No. 311 and Table 1.

(Comparative Example 3) The polyurethane resin having a sodium sulfonate group used in Example 3 was replaced with a polyurethane resin having no polar group [
The same procedure as in Example 3 was carried out except that N-23013 manufactured by Nippon Polyurethane Co., Ltd. was used instead.

The results are shown in FIG. 3 and Table 1.

Table 1 (Example 4) A magnetic layer composition having the composition shown below was prepared using a ball mill.
A dispersion liquid was obtained by mixing and dispersing for 72 hours, and a magnetic paint was prepared.

Go-containing y-Fe20: + magnetic powder 100
Parts [Go content 3% by weight, average major axis diameter 0.2gm, average axis ratio 1/101 Vinyl chloride-vinyl acetate-vinyl 14 parts Alcohol copolymer polyurethane 8 parts Myristic acid 1 part Polishing paste p,
14 parts [60 parts obtained in Example 1 Paste with specular reflectance of 65.3 (%)] Cyclohexanone 70 parts Toluene
60 parts methyl ethyl ketone 60 parts trifunctional isocyanate compound
Three parts of the resulting magnetic paint were applied onto a 14 uLm thick polyester base film to give a dry thickness of 44 m.

Next, after removing the solvent under heating, the surface was smoothed using a super calender, and the surface was smoothed to 12.65 mm.
A magnetic tape was produced by cutting it into @.

The magnetic properties of this magnetic tape were measured.

The results are shown in Table 2.

In addition, each characteristic was measured as follows.

Recording characteristics; The output at frequencies of 5 MHz and 7 MHz was measured, and the output of the tape produced in Comparative Example 4 described later was taken as a reference (OdB), and the output of other tapes was shown as a relative value.

Running durability: This magnetic tape was put into a video tape cassette with a playback length of 120 minutes, and was repeatedly run on a VHS video tape recorder at a tape speed of 3.3:1 cm for 7 minutes and a head load of 30 g. The number of runs until clogging occurred was measured. The measurement results were evaluated as follows.

○... No clogging occurred even after repeated running 100 times.

Δ: Clogging occurred after 40 to 70 repeated runs.

×: Clogging occurred after repeated running less than 30 times.

The results are shown in Table 2.

(Example 5) The same procedure as in Example 4 was carried out except that a vinyl chloride resin having a potassium sulfonate group was used in place of the vinyl chloride-vinyl acetate-vinyl alcohol copolymer.

The results are shown in Table 2.

(Example 6) The same procedure as in Example 4 was carried out except that a vinyl chloride resin having a potassium sulfonate group was used instead of polyurethane.

The results are shown in Table 2.

(Example 7) Except that a vinyl chloride resin having potassium sulfonate groups was used instead of the vinyl chloride-vinyl acetate-vinyl alcohol copolymer, and a vinyl chloride resin with increased potassium sulfonate groups was used instead of polyurethane. The same procedure as in Example 4 was carried out.

The results are shown in Table 2.

(Comparative Example 4) Polishing paste B [60 parts specular reflectance obtained in Comparative Example 1] was used instead of polishing paste A [paste obtained in Example 1 (paste with a 10 parts specular reflectance of 65.3 (%))] is 47
．． Example 4 except that a paste of 0 (%) was used.
It was done in the same way.

The results are shown in Table 2.

(Comparative Example 5) Polishing Paste A [60 parts obtained in Example 1 7 parts of α-8 203 (average particle size 0.2 gm) in place of 314 parts of paste with specular reflectance of li5.3 (%) The same procedure as in Example 4 was carried out except that .

The results are shown in Table 2.

Table 2 *l... Frequency; 5 MHz *2...4 Frequency; 7 MHz (Example 8) A magnetic layer composition having the composition shown below was prepared using a ball mill.
A dispersion liquid was obtained by mixing and dispersing for 72 hours, and a magnetic paint was prepared.

Ferromagnetic alloy powder Too part [Average major axis diameter 0.2 pm, average axial ratio 1/151 Vinyl chloride-vinyl acetate-vinyl 14 parts Alcohol copolymer polyurethane 8 parts Myristic acid 1 part Polishing paste A
14 parts [50 parts obtained in Example 1 Paste with specular reflectance of 65.3 (%)] Cyclohexanone 70 parts Toluene
60 parts methyl ethyl ketone 60 parts trifunctional isocyanate compound
Three parts of the obtained magnetic paint were applied onto a polyester base film having a thickness of 1 Gpm so that the dry thickness was 3 pm.

Next, the solvent was removed under heating, the surface was smoothed using a super calender, and the tape was cut to a width of 8 mm to produce an 8 mm tape.

Various properties of this 8 mm tape were measured.

The results are shown in Table 2.

In addition, each characteristic was measured as follows.

Recording characteristics: The output at a frequency of 5 MHz, 7 M) lz was measured, and the output of the other tapes was shown as a relative value, using the output of the tape produced in Comparative Example 6 described later as a reference (OdB).

Running durability: This 8 mm tape was played for 90 minutes and loaded into an 8 mm cassette, and played on an 8 mm video tape recorder at a tape speed of 1.42 cm.
The test tube was run repeatedly at a head load of 120 g per minute, and the number of runs until clogging occurred was measured. The measurement results were evaluated as follows.

O...i Only clogging occurred even after repeated running 00 times.

Δ: Clogging occurred after 40 to 70 repeated runs.

×: Clogging occurred after repeated running less than 30 times.

The results are shown in Table 3.

(Example 9) Polishing paste C [60'' specular reflectance obtained in Example 2] was used instead of polishing paste A [paste obtained in Example 1 with a 60 part specular reflectance of 65.3 (%)] is 75
．． Example 8 except that a paste of 4 (%) was used.
It was done in the same way.

The results are shown in Table 3.

(Example 10) Implemented except that a vinyl chloride resin having a potassium sulfonate group was used in place of the vinyl chloride-vinyl acetate-vinyl alcohol copolymer, and a vinyl chloride resin having a potassium sulfonate group was used in place of polyurethane. The same procedure as in Example 8 was carried out.

The results are shown in Table 3.

Example 11 Polishing paste A [Example 1
Polishing paste C [60″ paste obtained in Example 2 with a specular reflectance of 55j (%)]
The same procedure as in Example 8 was conducted except that a paste with a 0° specular reflectance of 75.4 (%) was used.

The results are shown in Table 3.

(Comparative Example 6) In place of polishing paste A [paste with a 60° specular reflectance of 65.3 (%) obtained in Example 1], polishing paste B [60° specular reflectance obtained in Comparative Example 1] was used. 47.
The same procedure as in Example 8 was carried out except that a paste of 0 (%)] was used.

The results are shown in Table 3.

(Comparative Example 7) Polishing paste D [60° specular reflectance obtained in Comparative Example 2] was used instead of polishing paste A [paste with a 65.3 (%) 60° specular reflectance obtained in Example 1]. 50.
The same procedure as in Example 8 was carried out except that a paste of 6 (%)] was used.

The results are shown in Table 3.

(Comparative Example 8) Polishing paste A [instead of 114 parts of the paste with a 60° specular reflectance of 65.1 (%) obtained in Example 1, α
The same procedure as in Example 8 was carried out except that 17 parts of -Al12 (h [average particle size: 0.2 gm) was used.

The results are shown in Table 3.

(Left below) Table 3 *1 Frequency; 5 MHz *2 Frequency; 7 MHz [Effects of the invention] The resin composition according to claim 1 has a specific polar group. Therefore, it is possible to provide a resin composition in which an inorganic filler is dispersed in a resin in a short period of time with a high degree of dispersion, and in which the dispersion state after dispersion is also stable.

Therefore, the resin composition according to claim 1, for example,
When used for cleaning tapes for magnetic heads of VTRs, tape recorders, etc., leader tapes for cassette tapes, polishing tapes, etc., it is possible to improve polishability, durability, runnability, etc.

Since the magnetic recording medium according to claim 2 uses the resin composition according to claim 1 in which the inorganic filler is uniformly dispersed in advance, the dispersibility of the inorganic filler in the magnetic layer is further improved. Therefore, it is possible to provide a magnetic recording medium that has excellent electromagnetic conversion characteristics such as short wavelength recording characteristics, durability, and runnability.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the results of 60' specular reflectance (X) at each dispersion time in Example 1 and Comparative Example 1. FIG. 2 is a diagram showing the results of 60° specular reflectance (%) at each dispersion time in Example 2 and Comparative Example 2. The third UA is a diagram showing the results of 60° specular reflectance (%) at each dispersion time in Example 3 and Comparative Example 3. FIG. 4 is an explanatory diagram showing wear bars used in Examples 1 to 3 of the present invention and Comparative Examples 1 to 3. FIG. 5 is a sectional view showing the relationship between the tape and the wear bar in measuring the polishing force in Examples 1 to 3 of the present invention and Comparative Examples 1 to 3. Jφ...wear bar, K@...corner, L...tape, M
...Wear marks, N...Width, P...Aspirations. Figure 1 Figure 2 Figure 3

Claims (2)

[Claims] (1) In a resin composition consisting of a resin having a polar group and an inorganic filler, the polar groups of the resin having a polar group are -SO_3M, -OSO_3M, -COOM, and ▲
There are mathematical formulas, chemical formulas, tables, etc.▼ (However, in the formula, M represents a hydrogen atom, lithium, sodium, or potassium, and M^1 and M^2 each represent a hydrogen atom, lithium, sodium, potassium, or an alkyl group. M^1 and M^2 may be the same or different.) A resin composition characterized by at least one type of polar group selected from the group consisting of: thing. (2) A magnetic recording medium comprising a magnetic layer containing the resin composition according to claim 1.