JPS63178171A - Radiation-curable magnetic paint composition - Google Patents

Abstract

PURPOSE:To provide the title compsn. which gives a coating film having excellent wear resistance, strength, etc., containing a specified compd. having both free isocyanate and (meth)acryloyl(oxy) groups, a resin having OH groups and no radiation-sensitive double bond. and magnetic powder. CONSTITUTION:A caprolactone polyester polyol (a) having at least three OH groups per molecule is reacted with an isocyanate compd.(b) such as tolylene diisocyanate and a compd. (c) having both OH and (meth)acryloyl(oxy) groups [e.g., 2-hydroxyethyl (meth)acrylate] to obtain a compd. (A) having both free isocyanate and (meth)acryloyl(oxy) groups. 5-40pts.wt. component A is blended with 85-5pts.wt. resin (B) having an MW of 2,000-50,000, at least one OH group and no radiation-sensitive double bond and 10-90pts.wt. magnetic powder (C) such as Co-doped r-Fe2O3, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a radiation-curable magnetic coating composition, and more particularly, it relates to a radiation-curable magnetic coating composition containing a combination of free isocyanate groups and (meth)acryloyl (oxy) groups in one molecule. A compound comprising a compound having a specific functional group and magnetic powder as a fundamental wave component can be crosslinked and cured by the action of active energy rays such as female radiation and light. The present invention relates to a coating composition for magnetic recording media.

[Conventional technology]

Conventionally, this type of magnetic paint resin assembly, that is, a paint composition for magnetic recording media, has been made by coating magnetic powder and vinyl chloride-vinyl acetate on a film-like support such as /lyethylene terephthalate or cellulose triacetate. Polymer resin, vinyl chloride-vinylidene chloride copolymer resin, butadiene-acrylonitrile copolymer resin, acrylic resin, epoxy resin,
Polyurethane resins have been used that have been kneaded with various binders such as cellulose derivatives and then coated into a shape.

Recently, with the aim of improving the durability of such magnetic recording media, resins that can be cured by irradiation with active energy rays such as ionizing radiation and light have been developed.

In other words, a method of using radiation-curable resin as a part of the binder is also being adopted.

Here, examples of resins that can be cured by active energy rays include polyester, (meth)acrylate, urethane,
(Meth) acrylate is a combination of various acrylic oligo9mers such as polyether and (meth)acrylate, and one ethylenically unsaturated double bond in the molecule. Monomers with (monofunctional monomers) and/or monomers can be used in combination with various reactive diluents such as monomers with two or more ethylenically unsaturated double bonds in one molecule (polyfunctional monomers). In addition to the basic composition, those containing a photo(polymerization) initiator or a (photo)sensitizer are used if necessary.

[Problem that the invention seeks to solve]

However, in conventional radiation-curable parallaxes made of such acrylic oligomers and reactive diluents, the mechanical strength of the cured film is generally low.

If the elastic modulus is designed to be high, the elongation tends to decrease rapidly, and conversely, if the elongation is designed to be high, the elastic modulus decreases significantly, which is a disadvantage when using these resins as binders for magnetic recording media. However, the performance of the magnetic coating was insufficient in terms of abrasion resistance, coating strength, and adhesion to the material.

[Means for solving problems]

However, the present inventors conducted extensive research in view of the various drawbacks in the prior art as described above, and as a result, identified a compound having both a free isocyanate group and a (meth)acryloyl (oxy) group in one molecule. A coating composition containing the compound as a basic component is crosslinked and cured by the action of radiation,
The inventors discovered that the cured coating provides excellent performance as a magnetic recording medium, leading to the completion of the present invention.

That is, (1) the present invention contains as essential constituents (4) a caprolactone polyester polyol and an isocyanate compound having three or more hydroxyl groups in the molecule, and a hydroxyl group and (
A compound having both a free isocyanate group and a (meth)acryloyl(oxy) group in the molecule, which is obtained by reacting these as an essential reaction component with a compound having both a meth)acryloyl(oxy) group, (B)
One molecular weight having one or more hydroxyl groups in the molecule is 2,000
A resin that does not have a radiation-sensitive double bond within the range of 0 to soo, ooo, and (6) magnetic powder, or a combination of these compounds (A), resin (B), and magnetic material. With powder (2).

(Comprised of a compound that has two or more urethane bonds and two or more (meth)acryloyl (oxy) groups in its molecule, it is crosslinked and cured by the action of active energy rays such as ionizing radiation and light. The present invention aims to provide a magnetic coating composition that can be used as a magnetic paint composition.

Here, a caprolactone polyester polyol having three or more hydroxyl groups in the molecule, an isocyanate compound, and a compound having both a (meth)acryloyl(oxy) group and a hydroxyl group are used as essential reaction components, and are obtained by reacting them. , the compound (4) having both a free isocyanate group and a (meth)acryloyl(oxy) group in the molecule contains one or more, preferably two or more, free isocyanate groups per molecule.
C(meth)acryloyl(oxy) group per molecule t1
This is a synonym for a compound containing more than one.

Among them, cabrolactone polyester polyol having three or more hydroxyl groups in the molecule.

Epsilon-caglolactone is prepared by a known method using a trivalent or higher, preferably tri- to hexavalent, alcohol such as glycerin, trimethylolethane, trimethylolgulon, -entaerythritol, or pentaerythritol as an initiator. Caprolactone polyester polyol obtained by ring-opening polymerization can be used, but especially those with a molecular weight of 3
00 or more, preferably 500 to 4,000, can be suitably used.

In addition, Mono KH2 is a typical isocyanate compound.
, 4-) lylene diisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate), 1,4-xylylene diisocyanate, diphenylmethane-4,4'-diisocyanate, 3-methyl-diphenylmethane-diisocyanate or Aromatic diisocyanate compounds such as 1,5-7tale diisocyanate; cycloaliphatic diisocyanate compounds such as dicyclohexylmethane diisocyanate or inphorone diisocyanate; and aliphatic diisocyanate compounds such as hexamethylene diisocyanate or lysine diisocyanate: Alternatively, an isocyanate compound obtained by hydrogenating the above diisocyanate compound having nine aromatic rings.

7t Toe contains bifunctional diisocyanate compounds such as hydrogenated xylylene diisocyanate or hydrogenated diphenylmethane-4,4'-diisocyanate, and each of these diisocyanate compounds and di- to hexavalent low-molecular alcohols such as trimethylolethane. A polyisocyanate compound obtained by addition reaction at a ratio of 2 equivalents of isocyanate group to 1 equivalent i of hydroxyl group: Maku is a billet type polyisocyanate obtained by reacting each diisocyanate compound with water. Compound:
Difunctional isocyanate compounds such as 2-isocyanate ethyl-2,6-cyincyanatohexanoate; or multimers obtained by converting the above-mentioned diisocyanate compounds into incyanurates.

Furthermore, as a compound having both a (meth)acryloyl (oxy) group and a hydroxyl group, 2-hydroxyethyl (
meth)acrylate, 2-hydroxypropyl(meth)
Acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4
-Hydroxybutyl (meth)acrylate-Polyethylene glycol mono(meth)acrylate, ? Lipropylene glycol mono(meth)acrylate, intererythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, glycerin mono(meth)acrylate
Acrylate, glycerin di(meth)acrylate, glycidyl (meth)acrylate-(meth)acrylic acid adduct, "Aroex M-154JC ε-caglolactone modified 2-hydroxyethyl (meth)acrylate manufactured by Toagosei Chemical Industry ■" , tris(2-hydroxyethyl)isocyanate di(meth)acrylate and N
- Typical examples include methylol (meth)acrylamide.

On the other hand, the molecular weight is 2, which has one or more hydroxyl groups in one molecule.
The resin (B) has a radiation-sensitive double bond in the range of 000 to soo, ooo, and has +! ! various cellulose derivatives such as vinyl acetate-vinyl acetate-vinyl alcohol copolymerized vinyl-vinyl acetate-vinyl alcohol-maleic acid copolymer, polyvinyl alcohol, cellulose acetate butyrate, cellulose acetate, cellulose globionate or nitrocellulose What about phenoxy resin? Copolymers containing (meth)acrylic esters including Rivinyl Ptyral, nine copolymers using (meth)acrylic esters containing hydroxyl groups, hydroxyl group-containing polyurethane resins, hydroxyl group-containing polyurethane resins, etc. Examples include liptadiene, hydroxyl group-containing polyester resin, and oil-modified alkyd resin. These can be used alone or in combination of two or more.

In addition, as a compound (C) having two or more urethane bonds and two or more (meth)acryloyl(oxy) groups in one molecule, the compound (A″f: as an essential reaction component in the preparation) A compound having a molecular weight of 1,000 to 3, which is obtained by reacting the isocyanate compound as mentioned above to be used, a compound having both a (meth)acryloyl (oxy) group and a hydroxyl group, and a podiol as listed below.
Urethane (meth)acrylate resins within the range of 0.00,000 can be used.

Known and commonly used polyols can be used, but
Typical examples include ethylene glycol, 1.3-7'propylene glycol, 1.2-propylene glycol, diethylene glycol, dipropylene glycol, neopentyl glycol, 1,3-butanediol, 4-butanediol, 1,6-hexanediol, 2.2.4-trimethyl-1,3-bentanediol, dichloroneointyl glycol, dibromoneopentyl glycol, hydroxypiparic acid neoynthyl glycol ester, cyclohexanediol Methylol, 1,4-cyclohexanediol, trimethylolethane, trimethylolglonoξheglycerin, 3-
Methylpentane-1,3,5-) diol, intererythritol, spiroglycol, hydrogenated bisphenol A
, 1 friend is r new: I-ru p M-8701L, BA
-E4, BA-IP or BA-P6J [ethylene oxide or propylene oxide adduct of bisphenol A, which is on the back of Nippon Nyukazai ■]: or various polyols such as those that have been suspended and various known and commonly used carboxylic acids as listed below. or polyester polyols obtained by esterification reaction with acid anhydrides thereof.

Typical calgenic acids or their anhydrides include maleic acid, fumaric acid, itaconic acid, citraconic acid,
Tetrahydrophthalic acid, het acid, hemic acid, chlorendic acid, dimer acid.

Adipic acid, succinic acid, alkenylsuccinic acid, sepatic acid, azelaic acid, 2,2,4-trimethyladipic acid, terephthalic acid, 2-sodium sulfoterephthalic acid,
2-Potassium sulfoterephthalic acid, isophthalic acid, 5-
Sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, orthophthalic acid, 4-sulfophthalic acid,
1.10-decamethylene dicarboxylic acid, mucone 11. L
Yutric acid, malonic acid, glutaric acid, trimellitic acid, hexahydrophthalic acid, tetrabromophthalic acid, methylcyclohexentric acid, pyromellitic acid!
or their acid anhydrides.

Caprolactone polyester polyols obtained by ring-opening polymerization of C-caprolactone using a di- to hexa-hydric alcohol such as ethylene glycol, neopentyl glycol, or trimethylolpropylene as an initiator; or ethylene Various alkylene oxides such as oxide or propylene oxide
Can be obtained by ring-opening polymerization with the L7t alcohols mentioned above?
Examples include real medium-sized polyols.

As the above-mentioned magnetic powder, known and commonly used powders can be used as they are, but representative ones include r-
Fe203. Fs, 04, CO Dogu r-Fe205° Co Dogu 1-F@205- Fe s O4 solid solution, Co-containing compound-coated r-Fe20. , Co-containing compound-coated type F@304 (including intermediates with r-Fe203), CrO2, barium ferrite, F
e, Co, Fe-Co, Fe-Ni, Co-
Ni% Fs-Co-Nl, Fe-Co-B
, Fe-Co-0r-B.

Examples of Co-N1-P include ferromagnetic metal powders such as Fs-Co-Ni-P.

When preparing the composition of the present invention using the compound (4), resin (B), compound (C), and magnetic powder (6) listed above, these components (4) and ( When component B) and fraction (D) are essential components, the usage ratio of component (A): (B) Ti5: @component is 5 to 40:85 to 5:10. A weight part ratio of 90 is appropriate, and on the other hand, these (4) fractions and (B
) component, (base 0 and component (9)) as essential components, (A) : (B) : (c)
: @The weight part ratio is 5 to 40:80 to 2:80 to 2
: It is appropriate that it falls within the range of 10 to 90.

However, when attempting to cure the composition of the present invention with ultraviolet rays, in any of the above cases, the proportion of magnetic powder (b) to be used should be that of compound (4) and resin (B). It should be stopped by 504 for the total weight of 504
When the amount exceeds 20%, it becomes difficult to cure the radiation-curable magnetic coating.

Radiation or active energy rays as used in the present invention collectively refers to ionizing radiation and light such as electron beams, α rays, β rays, r rays, X rays, neutron beams, and ultraviolet rays.

The radiation-curable resin composition of the present invention thus obtained is 1
Usually, it is sufficient to use an active energy source that has been suspended as it is, and to irradiate it with radiation or active energy rays for curing. If necessary, various known and commonly used reactive diluents may be added thereto.

Typical such reactive diluents include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-ethylhexyl (meth)acrylate%N-vinylpyrrolidone, tetrahydrofurfuryl (meth)acrylate, ) acrylate, carpitol (meth)acrylate, phenoxyethyl (meth)acrylate, dicyclopentadiene (meth)acrylate, 1
．． 3-butanediol di(meth)acrylate, 1.6
-Hexanethiol di(meth)acrylate, polyethylene glycol di(meth)azilylate.

Hydroxypiparic acid ester neopentyl glycol di(meth)acrylate, trimethylolguro/mantri(meth)acrylate, pentaerythritol tri(
meth)acrylate, inter-erythritol tetra(meth)acrylate or dipentaerythritol hexa(meth)acrylate.

When curing the resin of the present invention using ultraviolet rays as radiation or active energy rays, the wavelength is 1.
A photo (polymerization) initiator that dissociates and generates radicals upon irradiation with ultraviolet rays of .000 to 8,000X should be used. However, representative examples include acetophenones, benzophenone, Michler's ketone, 4-A/, henzin benzoate, pentwin, benzoin methyl ethers, benzyl dimethyl ketal, α-aziroxime ester,
These include thioxanthones, anthraquinones, and their various derivatives.

In addition, known and commonly used (photo)sensitizers can be used in combination with such photo(polymerization) initiators, but typical examples of such (photo)sensitizers include amines, ureas, and Examples include sulfur compounds, phosphorus-containing compounds, chlorine-containing compounds, nitriles and other nitrogen-containing compounds.

Furthermore, organic solvents commonly used as reaction solvents or diluting solvents can also be used, typical examples of such organic solvents being aromatic hydrocarbons such as toluene or xylene; ketones such as methyl ethyl ketone, methyl isobutyl ketone or cyclohexanone. Examples include esters such as methyl acetate, ethyl acetate or butyl acetate; alcohols such as methanol, ethanol, gulononol or butanol, cellosolve acetate, carpitol acetate, dimethylformamide, and tetrahydrofuran.

Furthermore, if necessary, known and commonly used additives such as a dispersant, a wetting agent, an abrasive or an antistatic agent may be added to the magnetic coating composition of the present invention without any problem.

Among them, first, as a dispersing agent, a compound having the general formula R1C0O such as caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, elaidic acid, linoleic acid, lylunic acid or stearolic acid is used.
012 to C18 fatty acids represented by H (R4 in formula 1 represents a monovalent organic group of C1 to C17) or lithium of each of these fatty acids,
Typical examples include metal soaps made of alkali metals such as sodium or potassium or alkaline earth metals such as magnesium, calcium or barium, as well as lentin and the like. In addition, higher alcohols with a CI of 2 or higher, various higher alcohols, and sulfuric esters can also be used.

Next, wetting agents such as silicone oil, graphite, molybdenum disulfide, and tungsten disulfide are C-C.
fatty acid esters consisting of a fatty acid consisting of a C3 to C12 alcohol, or a fatty acid of C17 or higher, and a m alcohol having a carbon number of 21 to 23 in total with the number of carbon atoms of the fatty acid. Typical examples include fatty acid esters.

However, as the abrasive, materials commonly used for this type of magnetic paint can be used, among which representative ones include fused alumina, silicon carbide, chromium oxide, corundum,
Examples include artificial corundum, diamond, artificial diamond, garnet, and emery whose main components are corundum and magnetite.

Furthermore, as antistatic agents, natural surfactants such as Kagen black and saponin; nonionic surfactants such as alkylene oxide type and glycerin type are glycidol type; higher alkylamines, quaternary ammonium Salts, pyridine and other heterocycles, and phosphoniums are cationic surfactants such as sulfoniums; contain acidic groups such as calzenic acid groups, sulfonic acid groups, phosphoric acid groups, sulfuric ester groups, or phosphoric ester groups. Anionic surfactants; or amino acids.

Representative examples of aminosulfonic acids and sulfuric esters of aminoalcohols include amphoteric active agents such as phosphoric esters of aminoalcohols.

The thus obtained radiation-curable magnetic coating composition of the present invention can be crosslinked and cured by the action of active energy rays, and can be used for magnetic recording media, etc., as described above.

〔Example〕

Next, the present invention will be explained in more detail according to Reference Examples, Examples, and Comparative Examples. In the following, unless otherwise specified, all parts and sections are based on weight, and resins are expressed in terms of solid content. value.

Reference Example 1 [Example of cleavage of compound (4)] Caprolactone with a molecular weight of 1,000 obtained by ring-opening polymerization of e-caprolactone according to a conventional method using trimethylolethane as an initiator in a reaction vessel equipped with a stirrer. 500 parts of polyester polyol.

261 parts of tolylene diisocyanate and 35 parts of toluene
1 part was charged, the temperature was raised to 70°C and the reaction was carried out, and when the isocyanate group content became constant, 58 parts of 2-hydroxyethyl acrylate was further charged and the reaction was continued.
The reaction is terminated when the isocyanate group content becomes constant, and the resulting resin is abbreviated as resin (A-1).

Reference Example 2 (same as above) 500 parts of caprolactone polyester polyol with a molecular weight of 1,000 obtained by ring-opening polymerization of ε-caprolactone by a known method using trimethylolpropane as an initiator in a reaction vessel equipped with a stirrer.

261 parts of tolylene diisocyanate and 37 parts of toluene
6 parts of 2-hydroxyethyl acrylate was added and the temperature was raised to 70°C to react, and when the isocyanate group content became constant, 116 parts of 2-hydroxyethyl acrylate was added and the reaction was continued until the isocyanate group content became constant. Ta. The resin obtained here is abbreviated as (A-2).

Reference Example 3 (same as above) A molecule obtained by ring-opening polymerization of ε-caprolactone using a conventional method using trimethylolethane as an initiator in a reaction vessel equipped with a stirrer! 500 parts of 2,000% caprolactone polyester 4-liol, 167 parts of inphorone diisocyanate and 301 parts of toluene were charged and reacted by raising the temperature to 70°C, until the isocyanate group content became constant and further 2-hydroxypropyl methacrylate 3
6 parts were charged and the reaction was continued until the isocyanate group content became constant. The following resin obtained here is ・(A
-3).

Reference Example 4 (same as above) 500 parts of caprolactone polyester polyol with a molecular weight of 1,000 obtained by ring-opening polymerization of e-caprolactone using pentaerythritol as an initiator in a reaction vessel equipped with a stirrer, 336 parts of hexamethylene diisocyanate
1 part of 2-hydroxyethyl methacrylate and 416 parts of toluene were charged, and the temperature was raised to 70°C to cause a reaction. When the isocyanate group content became constant,
The reaction was further continued by charging 30 parts, and the reaction was terminated when the isocyanate group content reached a constant level. The resin obtained here is abbreviated as resin (A-4).

Winterization Example 5 (same as above) 350 parts of caprolactone polyester polyol with a molecular weight of 700 obtained by ring-opening polymerization of ε-caprolactone using pentaerythritol as an initiator in a reaction vessel equipped with a stirrer, hydrogenated diphenylmethane-4,4 524 parts of '-diisocyanate and 458 parts of toluene were charged and reacted by raising the temperature at 70 tl:t. When the isocyanate group content became constant, 195 parts of 2-hydroxypropyl acrylate was further charged to increase the isocyanate group content. The reaction was continued until it became constant. The t-resin obtained here is abbreviated as resin (A-5).

Reference Example 6 (same as above) 300 parts of caprolactone polyester polyol with a molecular weight of 1,500 obtained by ring-opening polymerization of ε-caprolactone using pentaerythritol as an initiator in a reaction vessel equipped with a stirrer, 140 parts of tolylene diisocyanate, and toluene. Charge 198 parts and raise the temperature to 70°C to react, and at the 9th point when the isocyanate group content becomes constant, charge 23 parts of 2-hydroxyethyl acrylate and continue the reaction until the isocyanate group content becomes constant. I let it happen. The resin obtained here is abbreviated as resin (A-6).

Example 1 A paint was prepared by putting the following composition into a ball mill and mixing and dispersing it until it was sufficiently dispersed.

Co-containing compound deposited r-Fe20380 parts resin (A-1
) 10# toluene
9ON methyl isotutyl ketone (MIBK
) 90# Example 2 A paint was prepared by putting a composition in the following proportions into a goal mill and mixing and dispersing it until it was sufficiently dispersed.

20380 parts of γ-Fe coated with Co-containing compound (A-1
') 5 #Toluene
90 part MIBK
90 #Examples 3 to 5 Various magnetic paints were prepared in the same manner as in Example 1 except that 10 parts of the resin (A-1) was changed as described below.

Example 3 Resin (A-2) 5 parts #4
Resin (A-3) 5 #l 5 Resin (
A-4) 5 #Examples 6 and 7 In place of using resin (A-1), the same amounts of (A-5) and (A-6) were used as described below, respectively. Resin (A-5) 5 parts l 7
Resin (A-6) Various magnetic paints were prepared in the same manner as in Example 2, except that 5p was changed.

Example 8 A paint was prepared by putting a composition in the following proportions into a goal mill and mixing and dispersing it until it was sufficiently dispersed.

r-Fe20580 parts Resin (AI) 5# "Unidic V-4200J 5 tt Toluene
90 part MIBK
90 #Example 9 A paint was prepared by putting a composition having the following proportions into a goal mill and mixing and dispersing it until it was sufficiently dispersed.

Fe alloy magnetic powder 80 parts resin (A-
1) 5# “Vinylite VA
GHJ 10p toluene
90IMIBK
90 #Example 10 A paint was prepared by adding a composition having the following proportions to T-&-Lumil and thoroughly dispersing it.

Co-containing compound deposited r-Fe20. 40 parts Resin (A-1) 10 # "Unide 47ri V-4220J 20 y "Hierite vAGH" 24I Toluene 90IMIBK
901F Comparative Example 1 A paint was prepared by putting a composition in the proportions shown below into a Lumil and mixing and dispersing it until it was sufficiently dispersed.

Co-containing compound deposition - Fe205 80 parts "Hierite VAGHJ 10 tt Toluene 90IMIBK
901 Comparative Example 2 A paint was prepared by placing a composition in the proportions shown below in a ball mill and mixing and dispersing it until it was sufficiently dispersed.

r-Fe20. 80 parts [Seltsuba BTHI/2 J 101 Toluene
9th part 1MIBK
901 Comparative Example 3 A paint ft was prepared by placing a composition having the following proportions in a ZAR mill and mixing and dispersing it until it was sufficiently dispersed.

F. Alloy magnetic powder 80 parts "Vinyrite VAGHJ 10y Toluene
901MIBK
90! Example 4 A paint was prepared by putting a composition having the following proportions into a ball mill and mixing and dispersing it until it was sufficiently dispersed.

r-Fe20340 part “Kayarad DPHA J 24 tr
“Hierite vAGH” 3ON “Kaya Cure DETX J 3 If
"KayaCure DMBI J 3g Toluene 901MIBK
90 p The magnetic paints obtained in Examples 1 to 9 and Comparative Examples 1 to 3 were coated on a water-polished tin plate with a bar coater to a film thickness of 10 μm, dried, and then exposed to an electron beam at 6 M rad. It was irradiated and hardened. After heat curing at 60° C. for 3 days, the wear resistance of the magnetic coating was tested by performing a taper abrasion test.

Judgment method: In a taper wear test, a worn wheel of CS-10F was rotated 20 times and the wear loss at the point of contact was measured. The results are shown in Table 1.

Table 1 The magnetic paints obtained in Example 10 and Comparative Example 4 were coated on a wet-polished tin plate using a coater to a film thickness of 10 μm.
After coating and drying, it was cured by irradiating it with ultraviolet rays using an 80W/cIn ultraviolet irradiation device.
A magnetic coating film was obtained by heat curing at 0° C. for 3 days. The abrasion resistance of this magnetic coating film was tested by conducting a taper abrasion test.

Judgment method: Perform 20 rotations with a C8-10F wear wheel according to the taper wear test and measure the wear loss at the moment. The results are shown in Table 2.

Table 2 [Effects of the Invention] As is clear from the results in Tables 1 and 2, the magnetic coating composition of the present invention provides a coating film with excellent wear resistance.

Claims (1)

[Claims] 1. (A) Essential reaction of a caprolactone polyester polyol having three or more hydroxyl groups in the molecule, an isocyanate compound, and a compound having both a hydroxyl group and a (meth)acryloyl(oxy) group. A compound having both a free isocyanate group and a (meth)acryloyl(oxy) group in the molecule, which is obtained by reacting these as components, and (B) a compound having one or more hydroxyl groups in the molecule and having a molecular weight of 2. ,000 to 500,000, and (D) magnetic powder as essential components. 2. (A) Reacting a caprolactone polyester polyol having three or more hydroxyl groups in the molecule, an isocyanate compound, and a compound having both a hydroxyl group and a (meth)acryloyl (oxy) group as essential reaction components. (B) a compound having both a free isocyanate group and a (meth)acryloyl(oxy) group in the molecule, which is obtained by (C) a resin having no radiation-sensitive double bonds within the range of (C) having two or more urethane bonds and two or more (
A radiation-curable magnetic coating composition comprising a compound having both a meth)acryloyl(oxy) group and (D) magnetic powder as essential components.