JPS61192022A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a coated film having excellent adhesiveness and hardness by incorporating uniformly dispersed fine-powder magnetic particles E into a curable resinous composition contg. an epoxy compd. A having >=2 epoxy groups in the molecule, a photochemically polymerizable compd. B having a carboxyl group in the molecule or a mixture of the compd. B and another photochemically polymerizable compd. C and a specific compd. D to prepare a magnetic paint. CONSTITUTION:An epoxy compd. A having >=2 epoxy groups in the molecule is the epoxy compd. having >=2 epoxy groups in one molecule and polyepoxy compd. such as bisphenol A are exemplified. Unsaturated carboxylic acid compds. such as acrylic acid are exemplified as the photochemically polymerizable compd. B having >=1 carboxyl group in the molecule. A photochemically polymerizable compd. C is the photochemically polymerizable compd. having one photochemical polymerization double bond in the molecule and styrene compds. such as styrene can be exemplified. As the compd. D shown by formula 1, 3,3'4,4'-tetrabenzophenone can be exemplified. The curing by an activation beam such as UV rays and the complete curing by heating of the photochemically polymerizable compd. B or the mixture of the compd. B and another polymerizable compd. C are remarkably improved by the compd. D shown by formula 1.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention provides tapes and sheets in which fine powder magnetic particles are dispersed in a binder and a sub-magnetizable layer is laminated thereon.

The card, Dohumta, relates to a disk-front magnetic recording medium. More specifically, this magnetizable layer is cured with actinic light such as ultraviolet light.

The present invention relates to a magnetic recording medium obtained by completely curing the magnetic recording medium by heat treatment.

(“Conventional technology”) Traditionally used as a binder for magnetic recording media.

Ethyl cellulose, nitrocellulose, polyvinylidene resin, vinyl chloride-vinyl acetate copolymer, styrene-getadiene copolymer, polymethyl methacrylate resin, vinylidene chloride-methyl methacrylate copolymer, polyurethane resin, epoxy resin, polyester resin, butadiene-acrylonitrile copolymer, etc. have been used, but these binders simply solidify the resin component by evaporation of the solvent, resulting in insufficient adhesion of the magnetic recording layer. There is a drawback.

On the other hand, a method has been proposed in which an isocyanate compound is added to the binder as a crosslinking agent to improve the adhesion with the support and physical properties (Japanese Patent Publication No. 47-28048, etc.), but these methods do not require the addition of a reactive compound. Another drawback is that the pot life of the magnetic paint will be shortened.

There is a method of using an ultraviolet curable resin as a binder as described in Japanese Patent Application Laid-open No. 56-8468, but this method requires that magnetic paint containing a large amount of finely powdered magnetic particles is not sensitive to ultraviolet rays. There is a fatal flaw in that complete curing cannot be achieved due to insufficient penetration.

Separately, Japanese Patent Publication No. 57-50801 describes a curing method using an electron beam using a radiation-polymerized resin as a binder, but this method not only requires a huge amount of equipment but also makes it difficult to control the curing. However, there are drawbacks such as deterioration of the binder and support proceeding at the same time as curing.

On the other hand, the present inventors have already developed an epoxy compound (A) having at least two epoxy groups in the molecule and a photopolymerizable compound (B) having a carboxyl group in the molecule. We proposed the use of a curable resin composition comprising a mixture with a photopolymerizable compound (C) and a photoinitiator as a binder for magnetic recording media.

(Problems to be Solved by the Invention) The above binder is first cured using a photopolymerizable compound (B) having a carboxyl group in the molecule or the compound (B).
and another photopolymerizable compound (C) by irradiation with actinic rays to form a carboxyl group-containing polymer; 1. Then, by heating, the jepoxy compound (A) is converted into the carboxyl group-containing polymer.
It consists of two steps: reaction with the I/group-containing polymer and complete curing. However, the first reaction, that is, 1
Photopolymerizable compound (B) having a carboxyl group in the molecule
Alternatively, when the compound (B) and another photopolymerizable compound (C) are cured by actinic ray irradiation to form a carpoki V/L/ group-containing polymer, a large amount of subfine powder magnetic particles are contained. This has the disadvantage that the actinic rays are blocked, polymerization does not necessarily proceed sufficiently to the lower layer of the coating film, and even if the coating film is cured by the second heating stage, it does not have sufficient hardness. It turns out nine.

(Rounding means to solve the problem) In view of the above circumstances, the present inventors have developed a binder that has a long pot life, does not cause any equipment problems, and is easy to control the curing reaction, and is different from conventional ultraviolet curable binders. 9. We have conducted extensive research in order to find a new binder that is completely cured despite containing a large amount of finely powdered magnetic particles and that also provides sufficient coating hardness.As a result, we have developed a new binder with structural formula < The inventors have discovered that the following defects can be solved by adding a compound exhibiting the following characteristics.1 The present invention has been achieved.

That is, 1 the present invention coats a magnetic paint on a non-magnetic support, and
In the magnetic recording unit, the magnetic paint is an epoxy compound (A) having two or more epoxy groups in the molecule.
and a photopolymerizable compound (B) having a carboxyl group in the molecule, or a combination of this compound (B) and another photopolymerizable compound (C
) and a compound represented by structural formula (I) (D
This is a magnetic recording medium characterized in that it is a magnetic paint made by uniformly containing a fraction of finely powdered magnetic powder particles (E) in a curable resin composition containing the following:

(@L/S RlS R, I R3 or R4 represents an alkyl group having 1 to 12 carbon atoms.) What is the epoxy compound (A) having two or more epoxy groups in the molecule used in the present invention? , an epoxy compound having two or more epoxy groups in one molecule has an epoxy equivalent of 100 to 4,000. Preferably 100-1.00
It is 0.

Representative compounds include bispheno-A, bisphenol F, and halogenated bisphenol A.

Phenol novolak, talesyl novolak, polyepoxy compounds of polyhydric alcohols, N, N, N'.

N'-tetraglycidyl metaxylene diamine s Nl
N, N', N'-tetraglycidi/'113-bis(
Examples include aminopolyepoxy compounds such as aminomethyl) cyclohexane. These epoxy compounds can be used alone or in combination of two or more.

Further, epoxy compounds having one epoxy group in the molecule such as allyl glycidyl ether and phenyl glycidyl ether can also be used in combination.

Among these epoxy compounds having two or more epoxy groups in the molecule, preferred epoxy compounds include bispheno-A/A diglycidyl ether lv, phenol
Examples include novolac type polyepoxy compounds, cresol novolak type polyepoxy compounds, and polyhydric alcohol polyepoxy compounds.

The photopolymerizable compound (B) having one or more carboxyl groups in the molecule used in the present invention includes:

Examples include (+) unsaturated p-boxylic acid compounds such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, and fumaric acid, and (1) compounds represented by the following general formula (II).

(CH2”C-Coo sweetfish R2←ru ball R3 sho Coo) I
). ...(I[) (wherein R1 represents hydrogen or a methyl group, sR2 and R3 each represent an aliphatic, aromatic, or ring group residue, A represents an ester bond, and m and n each represent In general formula (II), %R2 is preferably a divalent to tetravalent hydrocarbon group having 2 to 10 carbon atoms or a hydroxyl group-containing hydrocarbon group, and R3 has 2 or more carbon atoms
Divalent aliphatic polybasic acid residues having a valence of 10 to 10, divalent aromatic polybasic acid residues having a valence of 6 to 15 carbon atoms, and 2 to 4 valent aromatic polybasic acid residues having a carbon number of 6 to IO. Preferably, it is a valent aliphatic polybasic acid residue.

Examples of the compound represented by the general formula (II) include the following compounds.

m=1. The compound where n=1 is 1, for example, succinic acid monoacryloyloxyethyl ester.

Succinic acid monomethacroyloxyethylene varnish 5P/L/
[Hereinafter, it will be abbreviated as succinic acid mono(meth)acryloyloxyethyl ester. ], phthalic acid mono(meth)acryloyloxyethyl ester/I/S maleic acid mono(meth)acryloyloxyethyl ester lv, tetrahydrophthalic acid mono(meth)acryloyloxyethyl ester/I/S hexahydrophthalic acid mono(meth) ) Acryloyloxyethyl ester, endo-bicyclol: 2,2,1) -5-heptene-2,3-
Dicarboxylic acid mono(meth)acryloyloxyethyl ester p, tetrahydrophthalic acid mono-2-(meth)acryloyloxy S/-1-(phenoxymethyl)ethyl ester, phthalic acid mono-2-hydroxy-3-(meth) Examples include acryloyloxypropyl ester A/, succinic acid mono-2-hydroxy-3-(meth)acryloyloxypropyl ester A/, and the like.

Examples of compounds where m=l and n=2 include 1, for example, trimellitic acid mono-2-(meth)acryloyloxyethyl ester/I/, propane-1,2,3-)dicarboxylic acid mono-
Examples include 1-(meth)acryloyloxyethyl ester.

m=1. Examples of compounds where n=3 include pyromellitic acid mono-2-(meth)acryloyloxyethyl ester, pentane-1,2,3,5-tetracarboxylic acid heptanoyl-(meth)acryloyloxyethyl ester, etc. be.

Examples of compounds where m=2 and n=1 include phthalic acid mono-(2,3-bis(meth)acryloyl poxyisopropyl) ester, methyltetrahydrophthalic acid heptano[2,3-bis(meth) Acrylo 4/L/Okifisoprobil] Esthe A/, Tetrahydrophthalic acid mono-
C2,3-bis(meth)acryloyloxyisopropyl] ester, succinic acid heptano[2,3-bis(meth)
Acryloyloxyisopropyl] ester, etc.

m=2. n=29 Compounds include 1, for example, trimellitic acid mono-C4,5-bis(meth)acryloyloxyneobenchi~]Este IV, trimellitic acid mono-(3
, 4-bis(meg)acryloyloxyisobutyl] ester.

m=3. Examples of compounds where n=2 include 1, for example, trimellitic acid mono-(3,4,5-)lis(meth)acryloyloxyneopentyl]ester/I/, propane-1,2
, 3-) recarboxylic acid di-1,2-(meth)acryloyl oxyV ethyl ester.

m=3. The compound of nx3 is 1, for example, pyromellitic acid mono-C3,4,5-tris(meth)acryloyloxyneobenchi~]esthe/L/1 pentane-1,2
, 3,5-tetracarboxylic acid tri-1.2.5-(meth)acryloyl oxyethyl ester.

Among the above-mentioned compounds, the photopolymerizable compound (B) having one or more hydroxyl groups in the molecule is used.

Particularly preferred is (1). These photopolymerizable compounds (B) having a carboxyl group in the molecule can be used alone or in combination with two or more, and in combination with one or more of the other photopolymerizable compounds (C) described later. can be used.

The amount of the photopolymerizable compound (B) having one or more carboxyl groups in the molecule in the photopolymerizable compound (B+C) used in the present invention is 10 to 100% by weight. If the blending amount is less than 10% by weight, the adhesion of the cured coating film obtained will be insufficient.The photopolymerizable compound (C) used in the present invention is one that has one or more photopolymerizable compounds in the molecule. It is a photopolymerizable compound with a double bond.

Examples of photopolymerizable compounds having one photopolymerizable double bond in the molecule include (1) styrenic compounds such as styrene, α-methylstyrene, and chlorostyrene;
1) Methi/V(meth)acrylate, methi/I/(meth)acrylate sn- and i-propy/&/(meth)
Acrylate, Q-, IIIH- and t-buty/L/
(meth)acrylate, 2-ethylhexyl (meth)acrylate, lauri A/(meth)acrylate, stearyl (meth)acrylate and other alkyl/&/(meth)acrylates
Acrylates, alkoxyalkyl such as methoxyethyl (meth)acrylate, ethoxymethip(meth)acrylate, ptoxyVethyl/I/(meth)acrylate, etc.
l/(meth)acrylates, allyloxyalkyl/I/(meth)acrylates such as fenoquine meth A/(meth)acrylate, hydroxyalkyl A/(meth)acrylates such as 2-hydroxyethyl (meth)acrylate, halogen Substituted alkyl lv(meth)acrylates, or polyoxyalkylene glycol mono(meth)acrylate such as polyethylene glycol mono(meth)acrylate, polypropylene glycol to mono(meth)acrylate, etc.
Meta)acrylic L/-) or alkoxypolyoxy 5
/A/ Substituted acrylic mono(meth)acrylates such as alkylene mono(meth)acrylate, tetrahydro 7
〃Heterocycle-containing (such as free/I/(meth)acrylate)
(II) Mono(meth)acrylates of alkylene oxide adducts of bispheno-A/A, such as ethylene oxide and propylene oxide adducts of bisphenol A, hydrogenated hispheno-/l/
A of ethylene oxide and pro? “Mono(meth)acrylates of alkylene oxide adducts of hydrogenated bisphenol A, such as L/n oxide adducts, (IV)
A terminal isocyanate group-containing compound GC1 obtained by reacting a diiso V anate compound and one or more alcoholic hydroxyl group-containing compounds in advance, and a compound containing one ( Urethane-modified mono(meth)acrylates having a meth)acryloyloxy group, epoxy V mono(meth)acrylates obtained by reacting acrylic acid or methacrylic acid with a compound having one or more epoxy groups in the molecule , and (Vl) Surigoesthe μ mono(meth)acrylates obtained by reacting acrylic acid or methacrylic acid as a carboxylic acid component and a polyhydric carboxylic acid and a polyhydric alcohol of dihydrity or more as an alcohol component. and so on.

Examples of photopolymerizable compounds having two photopolymerizable double bonds in the molecule include (1) ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, l,4-gutanediol di( Akylene glycol di(meth)acrylates such as meth)acrylate, neopentyl glycol di(meth)acrylate, l,6-hexanethiol di(meth)acrylate, cyethylene glycol di(meth)acrylate, triethylene glycol Di(meth)acrylate, dipropylene glycol di(meth)acrylate.

Polyethylene glycol di(meth)acrylate.

Polyoxyalkylene glyco-μ di(meth)acrylates such as polypropylene glycol di(meth)acrylate, halogen-substituted alkylene glycol di(meth)
Substituted alkylene glycol di(meth)acrylates such as acrylates.

(1) Hydrogenation of di(meth)acrylates, hydrogenation of alkylene oxide adducts of bisphenol A, such as ethylene oxide and propylene oxide adducts of bispheno-A/A; hydrogenation of ethylene oxide and propylene oxide adducts of bispheno-A/A; Bispheno-A/A
Di(meth)acrylates of alkylene oxide adducts, (1) A terminal isocyanate group-containing compound obtained by reacting a diisocyanate compound and two or more alco-/I/hydroxyl group-containing compounds in advance;
/I/l! ): Urethane-modified di(meth)acrylates having two (meth)acryloyloxy groups in the molecule obtained by reacting hydroxyl group-containing (meth)acrylates, (■) Two or more epoxy groups in the molecule Epoxy di(meth)acrylates obtained by reacting a compound having acrylic acid and/or methacrylic acid, (V)
Examples include oligoester di(meth)acrylates obtained by reacting acrylic acid or methacrylic acid and polyhydric carboxylic acid as the acid component with a polyhydric alcohol of dihydrity or more as the alcohol component.

Examples of photopolymerizable compounds having three or more photopolymerizable double bonds in the molecule include (1))! J Methylo〃 Poly(meth)acrylates of trihydric or higher aliphatic polyhydric alcohols such as propane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, etc., 3 Poly(meth)acrylate of halogen-substituted aliphatic polyhydric alcohol with higher value than 1! (1) A terminal isoV anate group-containing compound obtained by reacting a diisocyanate compound and a compound containing three or more alcoholic hydroxyl groups in advance.

Further, urethane-modified poly(meth)acrylates having three or more (meth)acryloyloxy groups in the molecule obtained by reacting alcoholic hydroxyl group-containing (meth)acrylates, (I) epoxy resins having three or more epoxy groups in the molecule; Examples include epoxy poly(meth)acrylates obtained by reacting acrylic acid and/or methacrylic acid with compounds having groups.

The epoxy compound (A) used in the present invention and the photopolymerizable compound (B) having a carboxyl group in the molecule are (B)
) and another photopolymerizable compound (C) is epoxy compound (A):photopolymerizable compound [(B) + (C)) = 10:90-90 :
10 (weight ratio), preferably epoxy compound (A):photopolymerizable compound [(B) or (B)+
(C)) The range is 20:80 to 80:20 (weight ratio). The blending amount of epoxy compound (A) is 10
If the weight is less than -9, the reaction between the photopolymerizable compound (B) having a carboxyl group in the molecule and the epoxy compound (A) is substantially too small, and a cured coating film with excellent adhesive properties etc. cannot be obtained. Dangerous.

Compound (D
) as 3.3',4,4〆-tetra(methylbaroxycarboni/L/)benzophenone, 3.3'
, 4,4'-tetra(ethylbaroxycarponi IV)
Benzophenone, 3.3',4.4'-tetra(n-
probilveroxycarboni/L/)benzophenone,
3.3',4.4'-tetra(i-probilveroxycarboni/I/)benzophenone, 3,3
', 4.4'-tetra(n-butylperoxycarbonyl A/)benzophenone, 3.3', 4.4'-(dai-butylperoxycarbonyl)benzophenone h:
L3't4+4'-(t-butylperoxycarbonyl/
Examples include I/) benzophenone, 3.3', 4.4'-(lauryl baroxycarboni/L/) benzophenone, and among these, 3.3', 4.4'-tetra(- ButylperoxyVcarboni/S/)penzophenone is preferred. These compounds may be used alone or in combination of two or more.

The compound (D) represented by the structural formula (I) may be used as a solution by dissolving it in an organic solvent such as toluene or xylene. The blending amount is the total amount of the epoxy compound (A) of the present invention and the photopolymerizable compound [B
or (B+C) ], the amount is 0.01 to 20% by weight, preferably 0.5 to 10% by weight.

In the present invention, as a photoinitiator, a compound other than the compound (D) represented by the above structural formula CI) may be contained in the magnetic paint if necessary. Examples of such compounds include ketals such as benzyl dimethyl ketal, benzoins such as benzoin methyl ether, benzoin ethyl ether, benzoin-i-propyl ether, benzoin, and α-methylbenzoin, and 9.10-antofuquinone.

anthofquinones such as 1-chloroanthraquinone, 2-chloroanthraquinone, and 2-ethylanthoquinone;
Benzophenones such as benzophenone, p-chlorobenzophenone, p-dimethylaminobenzophenone, 2
-Hydroxy-2-methylpropiophenone, 1-(,
4-isoprobilpheniA/)-2-hydroxy-2-
Propiophenones such as methylpropiophenone, suberones such as dibenzosuberone, dipheni/I/S/
S/L/phyto, tetramethylthiuram disulfide,
Examples include sulfur-containing compounds such as thioxanthone, color X class a such as methylene blue, eosin, and 7μ olecein, which may be used alone or in combination of two or more.

In the present invention, the amount of the photoinitiator blended is 0 to 20% by weight, preferably 0.5% by weight, based on the total amount of the epoxy compound (A), the photopolymerizable compound, and CB or (B+C)).
5ylO weight%.

In the present invention, when it is necessary to promote the reaction between the epoxy group and the carpoxy S/A/ group, it is effective to add a reaction accelerator. As a reaction accelerator.

For example, 2-methylimidazole, 2-ethylimidazole, 2,4-dimethylimidazole/I/, 2-ethyl-4-methifreimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1-viny/I/ −
2-methylimidazo-, 2-phenylimidazole,
1-vinyl-2-ethylimidazo-/I/, imidazo-
IV, 2-pheny/l/-4-methylimidazole, l-viny/L/-2+4-dimethylimidazole, l
-Imidazoles such as vinyl-2-ethyl A/-4-methylimidazole, benzyldimethylamine, 2,
4.6-) Lydimethymu aminophenol, triethanolamine, triethylamine% N,N-dimethylpiperidine, α-methylbenzyldimethylamine, N-methylmorpholine.

N,N-dimethylaminoethano-/L/, NtN-diethylaminoethano-/L'-N, N-dipropylaminoethanol, tertiary amines such as dimethylaminomethylphenol, triacetate of tridimethylaminomethylphenol, and Tertiary amine salts such as tribenzoate are used alone or in combination of two or more. In the present invention, the amount of these reaction accelerators added is determined by the epoxy compound (A) and photopolymerizable. Compound [B is (B+C)
) is 0.05 to 5% by weight, preferably 0.1 to 3.5% by weight.

The fine powder magnetic particles (E) used in the present invention are h
F e, r - F ex Os h Co Ig containing r4e3o3. Fe304m containing Fe94゜Co
Cobalt ferrite (Co0-Fezos), Cr
O2, Co-N1-p alloy, Co-Ni-Fe alloy.

Co-N1-Fe-B alloy, Fe-Ni-Zn alloy,
Fe-Mn-Zn alloy, Fe-Co-N1-p alloy, Ni-Co alloy, Fe-Ti-5i alloy, F
e-Co-5i alloy, Fe-Ni alloy.

Fe-Ag alloy, Fe-Cr-Co alloy, Fe-C
r-5i' alloy.

Fe-Mn-A1 alloy barium ferrite (BaFe
Known ferromagnetic fine powders such as BOx can be used.

The blending ratio of fine powder magnetic particles in magnetic paint is 30~
90% by weight, preferably 50-85% by weight.

More preferably, it is 60 to 80% by weight.

The curable resin composition used as the binder of the present invention can be easily produced by stirring and mixing at room temperature or under heating if necessary. In order to prevent thermal polymerization during production and dark reactions during storage, known agents such as hydroquinone, hydroquinone monomethyate, 1-butyl-catechol A/51)-benzoquinone, 2°5-t-butyl-hydroquinone, and phenothiazine are used. It is desirable to add a thermal polymerization inhibitor. The amount added is 0.001 to 0.1% by weight, preferably 0.00% by weight, based on the photopolymerizable compound of the present invention.
1 to 0.05 weight.

If it is necessary to adjust the viscosity of the magnetic paint of the present invention, an organic solvent may be added.

Examples of organic solvents that can be used include methanol, ethanol, i-propano/I/, and n-propanol.

Alcohols such as butano-p, esters such as methyl acetate, ethyl acetate, n-butyl acetate, ethyl lactate IW, and glycol monoethyl acetate.

Acetone, methyl ethyl ketone, methyl isobutyl ketone, ketones such as cyclohexanone, ethyl ether/
I/, glycol ~ ethers such as dimethyl ether, glycol monoethyl ether, and dioxane, aromatic hydrocarbons such as benzene, toluene, and xylene nato, methylene chloride, ethylene chloride, carbon tetrachloride, chlorohopm, trichloroethylene, trichloroethane, perchloro Chlorinated hydrocarbons such as ethylene, chlorobenzene, dichlorobenzene, and dimethylformamide.

Polar solvents such as dimethyl sulfoxide can be used alone or in combination of two or more.

The magnetic coating material of the present invention may optionally contain a plasticizer such as digtylphthalate or triphenyl phosphate, and dioctyl sulfonatriumsacinate.

t-Butylphenol-polystyrene ether/I/.

Add dispersants, lubricants, lubricants and various antistatic agents such as ethylnaphthalene-sulfonate sortasifuryl succinate, zinc stearate, soybean oil lecithin, silicone oil, polyesters and polyurethanes containing sodium sulfonate groups. You can also do that.

The crosstalk machine used for manufacturing the magnetic paint of the present invention includes 2
This roll mill, 3-roll mill/I/, ball mill, Toronmi p, sand grinder, attritor, speed impeller dispersion machine, ? Examples include rs speed stone mill, high speed impact mill, desopar, kneader 1 high speed mixer, homogenizer, ultrasonic dispersion machine, etc.

The magnetic paint of the present invention is coated on a non-magnetic support, and the coating methods include air doctor coat, grade fist coat, air knife coat, squeeze coat, roll coat, reverse coat, and impregnation coat. , transfer roll coat, gravure coat, kiss roll coat, cast coat, spray coat, spin coat, etc.

There are no particular restrictions on the shape of the support as long as it is a non-magnetic support, but it is usually in the form of a tape or sheet.

It is used in the form of disks, cards, or drums.

Materials for the nonmagnetic support include polyethylene terephthalate, polybutylene terephthalate (V-), polyethylene, polypropylene, and polybutadiene.

Polystyrene, polymethyl methacrylate, styrene
Acrylonitrile copolymer, styrene-acrylonitrile-getadiene copolymer, cellulose triacetate,
Cellulose diacetate, cellulose acetate butyrate, 7 μlose acetate propionate, polyvinyl chloride IV, polyvinylidene chloride, polycarbonate, polyphenylene sulfide, polyamide, polyimide,
Polyamideimide, phenolic resin, and epoxy resin.

Hard plastics such as unsaturated polyester resin, silicone resin, aluminum, copper, etc.

Examples of tin and zinc include metals such as non-magnetic alloys containing these, ceramics, glass, and various papers. Among these, plastics and metals are suitable. This non-magnetic support may be packed or packed on the back side for purposes such as anti-static, anti-blocking, anti-transfer, and to improve runnability.
May be coated.

After the magnetic paint is coated on the support, if a solvent is added, the solvent is vaporized, then a magnetic field is applied to orient the contained fine powder magnetic particles, and then immediately exposed to ultraviolet rays or electron beams. It is irradiated with actinic light such as, and then completely cured by heat treatment.

What is the UV light source used? tJ pressure mercury lamp.

Low-pressure mercury lamps, ultra-high pressure mercury lamps, metal halide lamps,
Examples include electrodeless high-pressure mercury lamps. When using an electron beam, a photoinitiator is not necessarily required.

In the case of ultraviolet rays, the irradiation amount generally requires 100 mJ/- or more as an integrated amount of ultraviolet light, preferably 500 mJ/- or more.
~5000 mJ/CIA. The ambient temperature during ultraviolet irradiation can range from room temperature to about 200°C, but when using plastic or paper as a support, the temperature range is from room temperature to 100°C.
A temperature range up to is preferred. Although ultraviolet irradiation is possible even in the presence of air.

It is more effective to perform this in the presence of an ominous gas such as nitrogen gas, carbon dioxide gas, or argon gas.

The heat treatment after irradiation with actinic rays is carried out using, for example, an infrared heater,
Known methods such as hot air heating and high frequency heating are used. The heat treatment temperature can be arbitrarily selected depending on the heat resistance of the support, but generally the temperature is 40 to 200°C, and in the case of plastics and papers, the temperature is preferably 40 to 100°C. The heat treatment time is several minutes to several hours. The surface of completely cured magnetic paint is generally smoothed.

The magnetic recording medium of the present invention can be used for magnetic tapes, video tapes, and magnetic cards by taking advantage of the above-mentioned advantages.

It can be used as a wide variety of magnetic recording media such as magnetic tickets, floppy disks, magnetic hard disks, and magneto-optical disks.

(for production) In the present invention, a compound (D) represented by structural formula (1) is used.

Photopolymerizable compound (B) having a carboxyl group in the molecule
It is presumed that Mayu significantly improves the curing of the compound (B) and other polymerizable compounds (C) by actinic rays such as ultraviolet rays and complete curing by heating.

(Examples) Examples are given below to explain the present invention more specifically, but the present invention is of course not limited by the examples.

In the examples, parts simply indicate parts by weight. Performance measurements in Examples and Comparative Examples were conducted using other methods. <Adhesion> Measurements were conducted using the cross-cut cellophane tape peel test (JIS D-0202) for cured magnetic paint films.

Pencil hardness test of cured magnetic paint film (JIS D-02
9 according to 02).

Example 1 Epicote 8, a bispheno-A/A type epoxy resin
28 (manufactured by I Yuka Fel) 190 parts, 216 parts of succinic acid monoacryloyl oxyethyl ester, 312 parts of tetrahydrofurfuryl acrylate, 1 vlOO part of benzyl dimethyl keter, 5 parts of N,N-diethyl ethanolamide and 3 parts. ,3'.

4.4'-tetra(1-butylbaroxycarbonyl)
10 parts of a 25% by weight solution of benzophenone in toluene was stirred and mixed at room temperature to obtain a uniformly transparent curable resin composition. 23 parts of this curable resin composition, 20,375 parts of r-Fe, 2 parts of lecithin, 70 parts of cyclohexanone, and 30 parts of toluene were placed in a glass bead type high-speed shaker and mixed for 1 hour. Then, a magnetic coating material showing good dispersibility was obtained. A friend gained.

This magnetic paint was applied onto a 125 μm polyethylene terephthalate film using a reverse coater to a thickness of IO μm in solid content, and dried at room temperature for 10 minutes.
The magnetic field was oriented with a magnetic field of 00 Oe. Then 5.
6ff water-cooled high-pressure mercury lamp at 300C) 7fJ /-
After irradiation, heat treatment was performed at 120°C for 30 minutes to obtain a cured film of magnetic paint.

Table 1 shows the measurement results of the performance of the obtained cured coating film.

Example 2 Epikote 10, a bisphenol A type epoxy resin
01 (manufactured by I Yuka Fel) 90 parts, succinic acid monoacryloyloxyethyl ester IL/43 parts, bispheno-A/A ethylene oxide 4 moy adduct diacrylate 204 parts, benzyl dimethyl ketal 100 parts, N
, 10 parts of N-diethylethanolamine and 3.3'
, 4,4'-tetra(t-butylbaoquinecarbony/
10 parts of a 25% by weight L/) benzophenone toluene solution were stirred and mixed at room temperature to obtain a uniform transparent curable resin composition. 25 parts of this attenuated resin composition, cobalt coated r-F
70 parts of ezOa, 2 parts of lecithin, and 100 parts of cyclohexanone were placed in a glass bead type high-speed shaker and mixed for 1 hour to obtain a magnetic paint weighing 7 tons and exhibiting excellent dispersibility. After coating and treatment in the same manner as in Example 1, ultraviolet rays were irradiated, and then heat treatment was performed.

The measurement results of the performance of the obtained cured magnetic paint film are shown in Table 1.
A cured magnetic paint film was obtained in the same manner as in Example 1 except that carboni/L/)benzophenone was not added. Table 1 shows the results of measuring the performance of the resulting hard-cured coatings.

Comparative Example 2 Example 2 except that 3.3',4.4'-tetra(t-butylperoxyVcarbonyl)benzophenone was not added.
In the same manner as above, a cured magnetic paint film was obtained. The measurement results of the performance of the obtained cold-cured coating film are shown in Table 1.9.

Example 3 Bispheno-1vA type epoxy resin (Ebico)
1001 (manufactured by I Yuka Shell Co., Ltd.) 90 parts, succinic acid mono-2-hydroxy S/-3-acrylic acid V-n-propylene ester/L 150 parts, bisphenol A ethylene oxide 4 mol fcf additive (D !/7 100 parts of y-lylate, 50 parts of benzyl dimethyl ketal, N
, 710 parts of N-diethylethanolamide and 3.3'
, 4,4'-tetra(t-butylperoxy V-carponi/
L/)25% by weight of benzophenone)/'ene solution IO
Stir and mix at part weight temperature to obtain a uniformly transparent curable resin composition. 40 parts of this curable resin composition, r-Fe20a
60 parts, 2 parts of V-tin, 180 parts of cyclohexanone, and 40 parts of toluene were mixed in a glass bead type high-speed shaker to approx.
After mixing for a period of time, a magnetic paint exhibiting good dispersibility was obtained.

Drop the obtained magnetic paint onto the aluminum substrate for the magnetic disk, which has been diamond ground in advance, through a nozzle. 3
After spin coating with a spinner at ,000 rpm, the organic solvent was vaporized at 60° C. for 30 minutes, and then magnetically oriented with a magnetic field of 1,000 steps.

Next, 5.6■ water-cooled ra-pressure mercury lamp TE 3,50077J
/- After irradiation, heat treatment was performed at 120°C for 30 minutes. Table 1 shows the measurement results of the performance of the obtained post-cured coating film.

Comparative Example 3゜3+3','+,t4'-tetra(t-buty~
A cured coating film of the magnetic paint was obtained in the same manner as in Example 3 except that benzophenone was not added. Table 1 shows the measurement results of the performance of the nine cured coatings obtained. fI-.

Table 1 (Effects of the Invention) In the present invention, by using the compound represented by the structural formula CI as a component of the magnetic paint, polymerization by active light and reaction by heating can be sufficiently carried out. ”
A subsequent coating film with excellent amta and hardness can be obtained.

Claims (1)

[Claims] In a magnetic recording medium in which a magnetic paint is applied on a non-magnetic support and cured, the magnetic paint contains an epoxy compound (A) having two or more epoxy groups in the molecule and a carboxyl group in the molecule. A curable resin composition containing a photopolymerizable compound (B) having a group or a mixture of the compound (B) and another photopolymerizable compound (C) and a compound (D) represented by the structural formula (I). A magnetic recording medium characterized in that it is a magnetic coating material containing fine powder magnetic particles (E) uniformly dispersed therein. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (I) (However, R_1, R_2, R_3 or R_4 represents an alkyl group having 1 to 12 carbon atoms.)