JPH10330647A - Transparent coating composition and curing thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a composition curable in a short time under energy beam irradiation and capable of giving coating films excellent in hardness, etc., by including inorganic particles having each specific hardness and size, inorganic particles differing in composition from the former inorganic particles and having each specific refractive index, hardness and size, and a specific monomer. SOLUTION: This transparent coating composition is obtained by including 1,5-17.5 wt.% of inorganic particles A>=10 in new Moh's hardness and 20-200 μm in average size, 23.5-65.5 wt.% of inorganic particles B differing in composition from the particles A, 1.40-1.60 in refractive index, >=5 in new Moh's hardness and <20 μm in average size, and a (meth)acryloyl group-bearing monomer, and pref. furthermore, a resin such as epoxy(meth)acrylate, urethane(meth) acrylate or polyester(meth)acrylate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent coating composition applied to a base material such as a decorative board to protect the base material while maintaining the appearance of the base material, and a method of curing the same. is there. More specifically, the present invention is cured in a short time by irradiation with energy rays, surface hardness, scratch resistance,
The present invention relates to a transparent coating composition that forms a coating film having excellent abrasion resistance and transparency, and a curing method that can cure the transparent coating composition in a short time.

[0002]

2. Description of the Related Art Conventionally, a transparent coating composition has been known which is applied to a base material such as a decorative board in order to improve abrasion resistance while maintaining the appearance of the base material.

For example, Japanese Patent Publication No. 57-1419 discloses a transparent synthetic resin paint containing mineral particles such as α-alumina having a new Mohs hardness of 10 or more as a transparent synthetic resin paint applied to the surface of a decorative substrate. Have been.

However, mineral particles such as α-alumina contained in the above-mentioned conventional transparent synthetic resin paint have a refractive index larger than 1.60, and generally have a refractive index of 1.40 to 1.6.
There is a large difference in the refractive index between the film and the synthetic resin coating film in the range of 0. Further, in the conventional transparent synthetic resin paint,
In order to improve the surface hardness and abrasion resistance of the coating film, it is necessary to use a relatively large amount of mineral particles. For this reason,
When the surface hardness and scratch resistance of the conventional transparent synthetic resin coating are improved, there is a problem that a transparent coating film cannot be obtained.

[0005] An opaque molded product having an appearance similar to that of ceramics, that is, a molded product containing two or more kinds of inorganic particles and a synthetic resin has been known as a so-called artificial marble.

For example, Japanese Patent Application Laid-Open No. S60-103603 discloses a synthetic resin binder, large-diameter abrasion-resistant inorganic particles having a particle diameter of 50 μm to 1 mm, and a large-diameter abrasion-resistant inorganic particle. Abrasion-resistant inorganic particles of a small particle size having a particle size of one-third or less of the conductive inorganic particles, and the mixing ratio of the synthetic resin binder and the both abrasion-resistant inorganic particles is 1: 1 by weight. (5 to 12) are disclosed.

[0007]

However, according to the above-mentioned prior art, both abrasion-resistant inorganic particles are combined with a synthetic resin binder having a weight of 1/5 or less of the both abrasion-resistant inorganic particles to obtain an opaque material. This is a technique for obtaining a molded product, not a technique for forming a transparent coating film. Therefore, no consideration is given to the refractive index of the small-sized inorganic particles.

[0008] Among the above conventional techniques, urethane resin, thermoplastic melamine resin, unsaturated polyester resin and the like are used as a raw material of a synthetic resin binder, because they are kneaded with both abrasion-resistant inorganic particles by energy ray irradiation. Can not be cured quickly.

[0009] Epoxy resins, thermoplastic melamine resins, acrylic resins, and the like must be dried by removing a solvent mixed when used as a paint, and cannot be quickly cured after being applied to a substrate. .

The unsaturated polyester resin generally contains styrene as a monomer. Therefore, even when the unsaturated polyester resin is irradiated with energy rays, the energy rays are absorbed by the benzene ring of styrene, and the vinyl group of styrene is hardly activated. Further, the fumarate group, which is a polymerizable double bond of the unsaturated polyester, has low reactivity to energy rays. As a result, the unsaturated polyester resin has a problem that it is hard to be cured by irradiation with energy rays and cannot be cured in a short time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and provides a coating film which cures in a short time by irradiation with energy rays and has excellent surface hardness, scratch resistance, abrasion resistance, and transparency. And a curing method capable of curing the above transparent coating composition in a short time.

[0012]

The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that the new Mohs hardness is 1 unit.
An inorganic particle A having an average particle diameter of not less than 0 and an average particle diameter in the range of 20 to 200 μm, a composition different from that of the inorganic particle A, and a refractive index in the range of 1.40 to 1.60; A transparent coating composition containing inorganic particles B having a hardness of 5 or more and an average particle diameter of less than 20 μm and a monomer having a (meth) acryloyl group is cured in a short time by irradiation with energy rays. Then, they found that a coating film excellent in surface hardness, scratch resistance, abrasion resistance, and transparency was formed, and completed the present invention.

That is, in order to solve the above-mentioned problems, the transparent coating composition of the present invention has a new Mohs hardness of 10 or more and an average particle diameter of 20 to 200 μm.
Having a composition different from that of the inorganic particles A, a refractive index in the range of 1.40 to 1.60, a new Mohs hardness of 5 or more, and an average particle diameter of 20 μm. Or less, and a monomer having a (meth) acryloyl group.

According to the above construction, a coating film excellent in abrasion resistance can be formed by containing the inorganic particles A having a new Mohs hardness of 10 or more and an average particle diameter of 20 to 200 μm, and the new Mohs hardness is high. By containing inorganic particles B having an average particle diameter of 5 or more and less than 20 μm, a coating film having excellent surface hardness and scratch resistance can be formed.

In addition, according to the above configuration, the refractive index of the inorganic particles B is 1.40 to 1.60, and the refractive index of the cured product obtained by curing the monomer having a (meth) acryloyl group ( (Generally, 1.40 to 1.60), so that a coating film having excellent transparency can be formed. Accordingly, a beautiful coated product having an appearance in which the surface of the base material is clearly seen through the coating film can be obtained.

Further, according to the above configuration, the monomer having a (meth) acryloyl group is easily activated and polymerized by irradiation with energy rays, so that it cures in a short time.

In addition, according to the above configuration, since the monomer having a (meth) acryloyl group is rapidly cured by the energy rays, it cures in a state where the inorganic particles A and the inorganic particles B in the coating film are uniformly dispersed. Surface hardness, abrasion resistance and abrasion resistance are further improved.

In order to solve the above-mentioned problems, the transparent coating composition of the invention according to claim 2 further comprises a resin having a (meth) acryloyl group in the transparent coating composition according to claim 1. It is characterized by:

According to the above arrangement, the monomer having a (meth) acryloyl group reacts with the resin having a (meth) acryloyl group by irradiation with energy rays,
A cured resin having an appropriate molecular weight and crosslink density is produced. For this reason, the strength and toughness of the coating film obtained by curing the transparent coating composition can be balanced.

According to a third aspect of the present invention, there is provided a transparent coating composition according to the first or second aspect, wherein the content of the inorganic particles A is 1.5. -17.5% by weight, and the content of the inorganic particles B is 23.5-65.5% by weight.

According to the above construction, the content of the inorganic particles A is 1.5 to 17.5% by weight in the transparent coating composition.
Within this range, the transparency and abrasion resistance of the coating film obtained by curing the transparent coating composition can be further improved. Moreover, according to the said structure, the content of the inorganic particle B is 23.5-65.
When the content is within the range of 5% by weight, the surface hardness and scratch resistance of the coating film obtained by curing the transparent coating composition can be further improved.

According to a fourth aspect of the present invention, there is provided a transparent coating composition according to the second or third aspect, wherein the resin having a (meth) acryloyl group is the same as that of the second or third aspect. , Epoxy (meth) acrylate, urethane (meth) acrylate, and polyester (meth) acrylate.

According to a fifth aspect of the present invention, there is provided a method for curing a transparent coating composition comprising the steps of curing the transparent coating composition according to any one of the first to fourth aspects. It is characterized by irradiation with active energy rays.

According to the above method, the transparent coating composition according to any one of claims 1 to 4 can be cured in a short time.

Hereinafter, the present invention will be described in detail. In this specification, the term "transparent coating composition" refers to a coating composition that mainly transmits specularly and allows the shape of the object to be seen clearly even when the object is viewed through the composition.

The transparent coating composition according to the present invention has a new Mohs hardness of 10 or more and an average particle diameter of 20 to
Inorganic particles A having a range of 200 μm, a composition different from that of the inorganic particles A, a refractive index in the range of 1.40 to 1.60, a new Mohs hardness of 5 or more, and an average particle size of Resin containing inorganic particles B having a particle size of less than 20 μm and a monomer having a (meth) acryloyl group (hereinafter, referred to as a (meth) acryloyl group-containing monomer), and optionally having a (meth) acryloyl group (Hereinafter, referred to as (meth) acryloyl group-containing resin).

The inorganic particles A may have a new Mohs hardness of 10 or more. When the new Mohs hardness of the inorganic particles A is less than 10, the abrasion resistance of the coating film obtained by curing the transparent coating composition becomes insufficient.

The inorganic particles A having a new Mohs hardness of 10 or more include α-alumina (new Mohs hardness 12), corundum (new Mohs hardness 12), and silicon carbide (new Mohs hardness 1).
3), silicon nitride (new Mohs hardness 13), boron carbide (new Mohs hardness 14), boron nitride (new Mohs hardness 1)
4) and diamond (new Mohs hardness of 15).

Incidentally, the new Mohs hardness is a value measured by scratching a sample sequentially with 15 kinds of minerals shown in Table 1 and, if the sample is damaged, the hardness is lower than that of the mineral.

[0030]

[Table 1]

The average particle size of the inorganic particles A is 20 to
The thickness may be within the range of 200 μm, but is more preferably within the range of 20 to 90 μm. If the average particle diameter of the inorganic particles A is less than 20 μm, the abrasion resistance of a coating film obtained by curing the transparent coating composition becomes insufficient, which is not preferable. On the other hand, when the average particle diameter of the inorganic particles A exceeds 200 μm, the dispersibility of the inorganic particles A in the transparent coating composition becomes poor, and as a result, the inorganic particles are contained in the coating film obtained by curing the transparent coating composition. A cannot be uniformly dispersed, which is not preferable.

The inorganic particles A include particles having a particle size of 5 μm or less.
It is preferably at most 0% by weight, more preferably at most 15% by weight. In the inorganic particles A, particles having a particle size of 20 μm or less are preferably 60% by weight or less, and more preferably 50% by weight or less. Further, the inorganic particles A are particles having a particle diameter of 200 μm or more.
It is preferably at most 5% by weight, more preferably at most 5% by weight. When the inorganic particles A are within the above range, the abrasion resistance is further improved.

The content of the inorganic particles A in the transparent coating composition is preferably in the range of 1.5 to 17.5% by weight. When the content of the inorganic particles A in the transparent coating composition is less than 1.5% by weight, the abrasion resistance of a coating film obtained by curing the transparent coating composition becomes insufficient. On the other hand, when the content of the inorganic particles A is more than 17.5% by weight, the transparency of a coating film obtained by curing the transparent coating composition deteriorates.

The refractive index of the inorganic particles B is 1.40 to 1.6.
The difference between the refractive index of the cured resin formed by curing the (meth) acryloyl group-containing monomer and the (meth) acryloyl group-containing resin included as required may be 0. 0.01 or less, and more preferably 0.005 or less in difference from the refractive index of the cured resin. When the refractive index of the inorganic particles B is within the above range, the refractive index of the cured resin material is generally 1.40 to 1.6.
Since it is within the range of 0, a transparent coating composition in which the refractive index of the cured resin is close to the refractive index of the inorganic particles B can be easily synthesized. When the refractive index of the inorganic particles B is out of the above range, it is difficult to obtain a coating having excellent transparency.

The inorganic particles B have a composition different from that of the inorganic particles A, have a new Mohs' hardness of 5 or more, and have a surface hardness and a resistance to a coating film obtained by curing the transparent coating composition. It has a function of improving abrasion resistance. When the new Mohs hardness of the inorganic particles B is less than 5, the surface hardness and the abrasion resistance of the coating film obtained by curing the transparent coating composition become low. The new Mohs hardness of the inorganic particles B is preferably 7 or more. Thereby, the surface hardness and scratch resistance of the coating film obtained by curing the transparent coating composition can be further improved.

The inorganic particles B having a refractive index of 1.40 to 1.60 and a new Mohs hardness of 5 or more include crystalline silica (quartz) having a refractive index of 1.553 and 1.554 and a new Mohs hardness of 8 ), Fused silica (quartz glass) having a refractive index of 1.4585 and a new Mohs hardness of 7, Vycor glass (Vycor glass; trade name of Corning) having a refractive index of 1.458, and a refractive index of 1 And soda-lime glass having a refractive index of 1.47 and borosilicate glass having a refractive index of 1.47.

The average particle diameter of the inorganic particles B may be less than 20 μm, but is more preferably in the range of 0.1 to 5 μm. When the average particle diameter of the inorganic particles B exceeds 20 μm, the surface hardness of a coating film obtained by curing the transparent coating composition becomes low.

In the inorganic particles B, particles having a particle size of 128 μm or more are preferably 4% by weight or less, more preferably 0.5% by weight or less. Further, the inorganic particles B
The content of the particles having a particle size of 24 μm or less is preferably 55% by weight or more, and more preferably 85% by weight or more. When the inorganic particles B are within the above range, the surface hardness and the scratch resistance are further improved.

The content of the inorganic particles B in the transparent coating composition is more preferably in the range of 23.5 to 65.5% by weight, and more preferably in the range of 31.5 to 59% by weight. Is more preferred. If the content of the inorganic particles B is less than 23.5% by weight in the transparent coating composition, the surface hardness and scratch resistance of the coating film obtained by curing the transparent coating composition will be low. Further, when the content of the inorganic particles B is more than 65.5% by weight in the transparent coating composition, the coating film obtained by curing the transparent coating composition becomes brittle, or the viscosity of the transparent coating composition becomes lower. It becomes too high, and the handleability of the transparent coating composition decreases. Further, when the content of the inorganic particles B is more than 65.5% by weight in the transparent coating composition, the relative content of the inorganic particles A in the transparent coating composition decreases, so that the transparent coating composition The abrasion resistance of the coating film obtained by curing the object is reduced.

The (meth) acryloyl group-containing monomer used in the present invention includes a monomer having one (meth) acryloyl group, a monomer having two (meth) acryloyl groups, and a monomer having three (meth) acryloyl groups. Or a monomer having four or more (meth) acryloyl groups.

Examples of the monomer having one (meth) acryloyl group include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and tert-butyl (meth). ) Acrylate, 2-ethylhexyl (meth)
Acrylate, isodecyl (meth) acrylate, n-
Lauryl (meth) acrylate, isooctyl (meth)
Acrylate, tridecyl (meth) acrylate, n-
Stearyl (meth) acrylate, isostearyl (meth) acrylate, behenyl (meth) acrylate, isoamyl (meth) acrylate, siamil (meth) acrylate, cyclohexyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, isobornyl (meth) acrylate Benzyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2
-Hydroxylpropyl (meth) acrylate, 2-hydroxylbutyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, methoxydipropylene glycol (meth) acrylate, methoxytripropylene glycol (meth) acrylate , 3-
Methoxybutyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, n-butoxyethyl (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, 2-phenoxyethyl (meth) acrylate, phenoxydiethylene glycol (meth) acrylate, phenoxypolyethylene glycol (Meth) acrylate, nonylphenoxyethyl (meth) acrylate, trifluoroethyl (meth) acrylate, dicyclopentenyloxyethyl (meth)
Acrylate, 2-acetoacetylethyl (meth) acrylate, and the like.

Examples of the monomer having two (meth) acryloyl groups include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate,
Triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, tetrapropylene glycol di (meth) acrylate, 1,4-butane Diol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,5-pentanediol di (meth) acrylate, 1,6-hexanediol di (meth) Acrylate, 1,9-nonanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, dibromoneopentyl glycol di (meth) acrylate, glycerin di (meth) acrylate, dimethylolt Shikurodekanji (meth) acrylate, di (meth) acrylate of ethylene oxide adduct of bisphenol A and the like.

Examples of the monomer having three (meth) acryloyl groups include trimethylolpropane tri (meth) acrylate, tetramethylol methane tri (meth) acrylate, tetramethylol methane tetra (meth) acrylate, and pentaerythritol tri ( (Meth) acrylate, glycerin tri (meth) acrylate and the like.

Examples of the monomer having four or more (meth) acryloyl groups include pentaerythritol tetra (meth) acrylate, ditrimethylolpropanetetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (Meth) acrylate and the like.

The transparent coating composition according to the present invention may contain a polymerizable unsaturated monomer other than the above (meth) acryloyl group-containing monomer. Examples of the polymerizable unsaturated monomer other than the (meth) acryloyl group-containing monomer include styrene, α-methylstyrene, divinylbenzene, vinyltoluene, p-methylstyrene, tert-butylstyrene, diallyl phthalate, and N-vinyl. And pyrrolidone. When the (meth) acryloyl group-containing resin is not used in the transparent coating composition, it is preferable to include a monomer having two or more (meth) acryloyl groups.

The transparent coating composition according to the present invention optionally contains a (meth) acryloyl-based resin. This makes it possible to balance the strength and toughness of the coating film formed by curing the transparent coating composition.

The (meth) acryloyl group-containing resin is preferably at least one resin selected from the group consisting of epoxy (meth) acrylate, urethane (meth) acrylate, and polyester (meth) acrylate. The above resin group includes inorganic particles A, inorganic particles B
And the adhesiveness to the substrate to be coated can be improved, so that the abrasion resistance and strength of the coating film obtained by curing the transparent coating composition can be improved.

The above-mentioned epoxy (meth) acrylate is
This is a resin obtained by subjecting an epoxy resin having two or more epoxy groups in a molecule to an esterification reaction with (meth) acrylic acid. Further, a polybasic acid may be further added to the reaction system of the above esterification reaction, if necessary.

The above epoxy resin is a polyfunctional epoxy compound having two or more epoxy groups in a molecule. Examples of the epoxy resin include bisphenol type epoxy resin, hydrogenated bisphenol type epoxy resin, novolak type epoxy resin, hydrogenated novolak type epoxy resin, and halogenated epoxy resin. The halogenated epoxy resin is an epoxy resin obtained by substituting a part of the hydrogen atoms of the bisphenol epoxy resin or the novolak epoxy resin with a halogen atom such as a bromine atom or a chlorine atom. One of these exemplified epoxy resins may be used alone, or two or more of them may be used in combination.

As the bisphenol type epoxy resin,
Specifically, for example, a glycidyl ether type epoxy resin obtained by reacting epichlorohydrin or methyl epichlorovidrin with bisphenol A or bisphenol F; reaction of an alkylene oxide adduct of bisphenol A with epichlorohydrin or methyl epichlorohydrin And the like.

Specific examples of the hydrogenated bisphenol type epoxy resin include, for example, epichlorohydrin or methyl epichlorohydrin and hydrogenated bisphenol A
Or glycidyl ether type epoxy resin obtained by reaction with hydrogenated bisphenol F; epoxy resin obtained by reaction of alkylene oxide adduct of hydrogenated bisphenol A with epichlorohydrin or methyl epichlorohydrin.

Specific examples of the novolak type epoxy resin include an epoxy resin obtained by a reaction of phenol novolak or cresol novolak with epichlorohydrin or methyl epichlorohydrin. Specific examples of the hydrogenated novolak epoxy resin include an epoxy resin obtained by a reaction of hydrogenated phenol novolak or hydrogenated cresol novolac with epichlorohydrin or methyl epichlorohydrin.

The average epoxy equivalent of the epoxy resin is 15
It is preferably within a range of 0 to 900, and 150 to 4
More preferably, it is within the range of 00. When the average epoxy equivalent of the epoxy resin exceeds 900, the viscosity of the epoxy (meth) acrylate becomes too high. Therefore, the handleability of the transparent coating composition containing the epoxy (meth) acrylate decreases.

The above (meth) acrylic acid is acrylic acid and / or methacrylic acid. Also, (meta)
A part of acrylic acid can be used by replacing it with another unsaturated monobasic acid such as cinnamic acid, crotonic acid, sorbic acid, and half ester of unsaturated dibasic acid.

Examples of the above-mentioned polybasic acid used as needed include, for example, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, adipic acid, azelaic acid, Examples include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, trimellitic anhydride, dodecane diacid, dimer acid and the like.

The ratio of the total amount of the (meth) acrylic acid used and the amount of the polybasic acid used as required to the amount of the epoxy resin used is determined by the ratio of the carboxyl groups of the (meth) acrylic acid and the polybasic acid. The ratio of the total of the groups to the epoxy groups of the epoxy resin is 1: 1.2 to 1.2:
It is preferable to set the ratio to be in the range of 1.

The above esterification reaction proceeds easily when it is carried out in the presence of an ester catalyst. As the esterification catalyst, a conventionally known compound can be used. Specifically, for example, triethylamine, N, N
Tertiary amines such as -dimethylbenzylamine and N, N-dimethylaniline; quaternary ammonium salts such as trimethylbenzylammonium chloride and pyridinium chloride; triphenylphosphine, tetraphenylphosphonium chloride, tetraphenylphosphonium chloride; Tetraphenylphosphonium bromide,
Phosphonium compounds such as tetraphenylphosphonium iodide; sulfonic acids such as p-toluenesulfonic acid; and organic metal salts such as zinc octylate. The reaction method and reaction conditions of the esterification reaction are not particularly limited. In the esterification reaction, a polymerization inhibitor or molecular oxygen is added to the reaction system to prevent gelation due to polymerization. It is more preferred to add

The polymerization inhibitor is not particularly limited, and a conventionally known compound can be used. As the polymerization inhibitor, specifically, for example, hydroquinone, methylhydroquinone, p-tert-
Butylcatechol, 2-tert-butylhydroquinone, toluhydroquinone, p-benzoquinone, naphthoquinone, methoxyhydroquinone, phenothiazine, hydroquinone monomethyl ether, trimethylhydroquinone, methylbenzoquinone, 2,5-di-tert-butylhydroquinone, 4-hydroxy-2 , 2,6,6
-Tetramethylpiperidine-1-oxyl, copper naphthenate and the like.

The molecular oxygen may be supplied, for example, by blowing air or a mixed gas of air and an inert gas such as nitrogen into the reaction system (so-called bubbling).
In order to sufficiently prevent gelation due to polymerization, it is preferable to use a polymerization inhibitor and molecular oxygen in combination.

The epoxy (meth) acrylate preferably has a number average molecular weight in the range of 900 to 5,000, more preferably in the range of 1,300 to 2,500. In the case of a transparent coating composition containing an epoxy (meth) acrylate having a number average molecular weight of less than 900, the coating film becomes brittle. On the other hand, in the case of a transparent coating composition containing an epoxy (meth) acrylate larger than 5,000, the viscosity is significantly increased, and thus the handleability is reduced. In addition, the curability of the transparent coating composition is poor.

The urethane (meth) acrylate used in the present invention is a method of subjecting a polyisocyanate compound, a polyol compound, and a hydroxyl group-containing (meth) acrylate to a urethanization reaction; a polyol compound and a (meth) acryloyl group-containing isocyanate. It is a resin obtained by any one of a method of urethanizing a compound and a method of urethanizing a hydroxyl group-containing (meth) acrylate and a polyisocyanate compound.

Examples of the polyisocyanate compound include, for example, 2,4-tolylene diisocyanate and its hydride, various isomers of 2,4-tolylene diisocyanate and their hydrides, diphenylmethane diisocyanate, Hydrogenated diphenylmethane diisocyanate, hexamethylene diisocyanate,
Hexamethylene diisocyanate trimer, isophorone diisocyanate, xylene diisocyanate, hydrogenated xylene diisocyanate, dicyclohexylmethane diisocyanate, o-tolidine diisocyanate, naphthalene diisocyanate, triphenylmethane triisocyanate, "Millionate MR" (trade name, Nippon Polyurethane Industry Co., Ltd.) "Coronate L" (trade name, manufactured by Nippon Polyurethane Industry Co., Ltd.), "Barnock D-750" (trade name, manufactured by Dainippon Ink and Chemicals, Inc.), "Chris Bon NX" (trade name, Dainippon Ink. Chemical Industry Co., Ltd.), "Death Module L" (trade name, manufactured by Sumitomo Bayer Urethane Co., Ltd.), "Takenate D10
2 "(trade name, manufactured by Takeda Pharmaceutical Co., Ltd.).

Examples of the above polyol compound include, for example,
Examples include polyether polyol, polyester polyol, polybutadiene polyol, and adducts of bisphenol A with alkylene oxides such as propylene oxide and ethylene oxide.

Specific examples of the above polyether polyol include polyoxyethylene glycol, polyoxypropylene glycol, polytetramethylene glycol, polyoxymethylene glycol, and the like. The number average molecular weight of the polyether polyol is 3
It is preferably in the range of 00 to 5,000, and 50
More preferably, it is in the range of 0 to 3,000.
Further, the number average molecular weight of the polyester polyol,
It is preferable to be in the range of 1,000 to 3,000.

The hydroxyl group-containing (meth) acrylate is a (meth) acrylate having at least one hydroxyl group in the molecule. The hydroxyl group-containing (meta)
As the acrylate, specifically, for example, 2
-Hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, polypropylene glycol mono (meth) acrylate and the like.

The (meth) acryloyl group-containing isocyanate compound has at least one (meth)
A compound having an acryloyl group and at least one isocyanate group. As the (meth) acryloyl group-containing isocyanate compound, specifically, for example, methacryloyloxymethyl isocyanate,
Methacryloyloxyethyl isocyanate; a compound obtained by subjecting the hydroxyl group-containing (meth) acrylate to a polyisocyanate compound to a urethanization reaction at a molar ratio of 1: 1 and the like.

The reaction method in the urethanization reaction is not particularly limited. In addition, reaction conditions such as a reaction temperature and a reaction time in the urethanization reaction may be appropriately set so that the reaction is completed, and are not particularly limited. For example, when a polyisocyanate compound, a polyol compound, and a hydroxyl group-containing (meth) acrylic acid ester are subjected to a urethanization reaction, the following method may be used. That is, first, a polyisocyanate compound and a polyol compound are urethanized to form a prepolymer having an isocyanate group at the end, and then a methacrylate is mixed with a hydroxyl group-containing (meth) acrylic ester to cause a urethanization reaction. . In the above method, the amount of each compound used is such that the ratio (NCO group / hydroxyl group) of the isocyanate group of the polyisocyanate compound to the hydroxyl group of the polyol compound is in the range of 3.0 to 2.0, and It is adjusted so that the isocyanate group of the polymer and the hydroxyl group of the hydroxyl group-containing (meth) acrylic ester are substantially equivalent.

In the reaction system of the urethanization reaction, it is preferable to use a urethanization catalyst in order to accelerate the urethanization reaction. Examples of the urethanization catalyst include tertiary amines such as triethylamine; and metal salts such as di-n-butyltin dilaurate, and any general urethanization catalyst can be used. Further, it is preferable to add a polymerization inhibitor or molecular oxygen to the reaction system of the urethanization reaction in order to prevent gelation due to polymerization. As the above-mentioned polymerization inhibitor and molecular oxygen, those mentioned in the above-mentioned epoxy (meth) acrylate can be similarly used.

The number average molecular weight of the urethane (meth) acrylate is preferably in the range of 800 to 8,000, more preferably in the range of 1,000 to 5,000. In the case of a transparent coating composition containing a urethane (meth) acrylate having a number average molecular weight of less than 800, the coating film becomes brittle. On the other hand, the number average molecular weight is 8,000
In the case of a transparent coating composition containing a larger urethane (meth) acrylate, the viscosity is significantly increased, so that the handleability is reduced. In addition, the curability of the transparent coating composition is poor.

The polyester (meth) used in the present invention
Acrylate is a resin obtained by subjecting a saturated polyester or unsaturated polyester to an esterification reaction with a (meth) acryloyl group-containing compound. Polyester (meth) acrylate is obtained by esterifying the hydroxyl group of a saturated polyester or unsaturated polyester with (meth) acrylic acid, or esterifying the carboxyl group of the saturated polyester or unsaturated polyester with glycidyl (meth) acrylate. It can be easily obtained by the following method.

The above-mentioned saturated polyester is obtained by a condensation reaction between a saturated dibasic acid and / or an acid anhydride thereof and a polyhydric alcohol. Further, the unsaturated polyester is obtained by mixing an α, β-unsaturated dibasic acid and / or an acid anhydride thereof, a polyhydric alcohol, and a saturated dibasic acid and / or an acid anhydride thereof optionally used. Obtained by a condensation reaction.

Examples of the α, β-unsaturated dibasic acid and / or anhydride thereof include, for example, maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid and the like. No.

Specific examples of the above-mentioned saturated dibasic acids and / or acid anhydrides include phthalic acid, phthalic anhydride, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, tetrahydrophthalic anhydride, hexahydrophthalic acid Acid, hexahydrophthalic anhydride, cyclohexanedicarboxylic acid, succinic acid, malonic acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, glutaric acid, 1,12
-Docanedioic acid, dimer acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic anhydride, 4,4'-biphenyldicarboxylic acid And the like.

Examples of the polyhydric alcohols include, for example, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol,
1,3-butanediol, 1,4-butanediol,
1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 1,4-cyclohexanediol, 1,3-cyclohexanediol, 1,2-
Cyclohexanediol, 1,4-cyclohexanedimethanol, 2-methylpropane-1,3-diol, hydrogenated bisphenol A, adducts of bisphenol A with alkylene oxides such as propylene oxide and ethylene oxide, and trimethylolpropane. Can be

The reaction method and the like of the above condensation reaction can be carried out by a known method, and are not particularly limited. The mixing ratio of the dibasic acids and the polyhydric alcohols is not particularly limited. Further, in the above-mentioned condensation reaction, additives such as a catalyst and an antifoaming agent may be used as necessary, but the amount of use is not particularly limited. Further, the reaction temperature and the reaction time in the above condensation reaction,
What is necessary is just to set suitably so that the said reaction may be completed, and it is not specifically limited.

The number average molecular weight of each of the saturated polyester and the unsaturated polyester is 500 to 3,000.
It is preferably within the range of 0. Number average molecular weight is 3,
In the case of a polyester (meth) acrylate obtained from a saturated polyester or an unsaturated polyester having a molecular weight of more than 000, the viscosity becomes extremely high, and the handleability of a transparent coating composition containing the same decreases.

Further, the esterification reaction between the hydroxyl group of the above-mentioned saturated polyester or unsaturated polyester and (meth) acrylic acid, or the carboxyl group of the saturated polyester or unsaturated polyester and glycidyl (meth)
It is preferable to add a polymerization inhibitor or molecular oxygen to the reaction system of the esterification reaction with the acrylate in order to prevent gelation due to polymerization. As the above-mentioned polymerization inhibitor and molecular oxygen, those mentioned in the above-mentioned epoxy (meth) acrylate can be similarly used.

The reaction conditions such as the reaction temperature and reaction time in the above esterification reaction may be appropriately set so that the reaction is completed, and are not particularly limited. In the esterification reaction, it is preferable to use the ester catalyst described above in order to promote the reaction. Further, the esterification reaction between the unsaturated monobasic acid and the hydroxyl group of the saturated polyester or unsaturated polyester, if necessary,
A solvent may be used.

Examples of the solvent include, but are not particularly limited to, aromatic hydrocarbons such as toluene. The amount of the solvent used and the method of removing the solvent after the reaction are not particularly limited. In the above esterification reaction, water is produced as a by-product. Therefore, in order to accelerate the reaction, it is preferable to remove by-product water from the reaction system. The method for removing water is not particularly limited.

The weight ratio of the (meth) acryloyl group-containing resin to the (meth) acryloyl group-containing monomer in the transparent coating composition of the present invention ((meth) acryloyl group-containing resin / (meth) acryloyl group-containing monomer) Body) is 2/8 ~
It is preferably within the range of 7/3, and it is 3/7 to 6/4.
Is more preferably within the range. When the above weight ratio exceeds 7/3, the viscosity of the transparent coating composition becomes too high, and the handleability decreases. In addition, when the weight ratio is 2
When the ratio is / 8 or more, the adhesion between the cured resin in the transparent coating composition, the inorganic particles A, the inorganic particles B and the substrate to be coated is improved, and the strength and abrasion resistance of the coating film are improved. It is preferred because it improves.

It is preferable to add a polymerization inhibitor to the transparent coating composition according to the present invention in order to improve storage stability and adjust curability. As polymerization inhibitors,
The polymerization inhibitors exemplified above can be used.

In the transparent coating composition according to the present invention, particularly when ultraviolet curing is performed, it is preferable to incorporate a polymerization initiator and a photosensitizer in order to improve the curing speed.

Examples of the polymerization initiator include benzoin ethers such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether and benzyl dimethyl ketal; and benzyl such as dimethoxyphenyl acetophenone and hydroxycyclohexyl phenyl ketone. Ketals; diethoxyacetophenone, 4-te
acetophenones such as rt-butylchloroacetophenone; 2-dimethylaminoethylbenzoate, p-dimethylaminoethylbenzoate, diphenyldisulfide, benzophenone and its derivatives, benzyl and its derivatives, 2-chlorothioxanthone, thioxanthone and its derivatives, anthraquinone and its Derivatives, acylsulfin oxides, camphorquinones, methylphenylglyoxylate, and the like. Examples of the photosensitizer include amines, ureas, sulfur compounds, nitrile compounds, phosphorus compounds, urea compounds, chlorine compounds, and the like.

The amount of the polymerization initiator is preferably in the range of 0.1 to 10 parts by weight based on 100 parts by weight of the transparent coating composition. The transparent coating composition may further include an auxiliary material (additive) and the like as necessary. As the auxiliary materials (additives), colorants such as pigments and dyes,
Extender, ultraviolet absorber, antioxidant, stabilizer (anti-gelling agent), plasticizer, leveling agent, defoamer, silane coupling agent, antistatic agent, flame retardant, lubricant, thinner, low Examples thereof include a shrinking agent, inorganic particles (inorganic filler) other than the inorganic particles A and B, an organic filler, a desiccant, a dispersant, and the like.

As described above, the transparent coating composition according to the present invention has an inorganic particle A having a new Mohs hardness of 10 or more and an average particle diameter in the range of 20 to 200 μm.
And a composition different from that of the inorganic particles A, and the refractive index is 1.40.
An inorganic particle B having a new Mohs hardness of 5 or more and an average particle diameter of less than 20 μm,
(Meth) acryloyl group-containing monomer. This makes it possible to provide a transparent coating composition that cures in a short time by irradiation with energy rays and forms a coating film having excellent surface hardness, scratch resistance, abrasion resistance, and transparency.

The transparent coating composition according to the present invention forms a coating film on a substrate by being cured after being applied on the substrate. The above-mentioned substrate is not particularly limited, and can be widely used for paper, wood, decorative board, glass, molded plastic, and metal plate.

The method for applying the transparent coating composition on the above substrate may be a conventional method, for example, a roll coater method, a reverse coat method, a flow coater method, a curtain flow coater method. , A die coater method, a bar coater method, a spray coat method, a spin coat method, a brush coating method and the like.

The method of curing the transparent coating composition is not particularly limited, but a method of irradiating the transparent coating composition with an active energy ray is particularly preferable.
According to the above method, the transparent coating composition applied on the base material is rapidly cured, and the coating film can be formed in a short time.

The active energy ray may be an energy ray capable of polymerizing a (meth) acryloyl group-containing monomer in the transparent coating composition, and examples thereof include an ultraviolet ray, an electron beam, an ion beam, and a radiation. Can be

The apparatus used for irradiating the active energy ray is not particularly limited. Examples of the ultraviolet irradiating apparatus include a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a metal hydride lamp, a xenon lamp, and an excimer lamp. Can be used.
Examples of the electron beam irradiation device include a scanning electron curtain type electron beam irradiation device, a curtain type electron beam irradiation device, a laminar type electron beam irradiation device, an area beam type electron beam irradiation device, and a broad beam type electron beam irradiation device. And a pulse beam type electron beam irradiation device.

The irradiation conditions of the active energy beam are not particularly limited, but the irradiation conditions of the electron beam are as follows.
Preferably, it is within the range of 100 mA, an acceleration voltage of 100 to 1000 kV, and an irradiation dose of 3 to 40 Mrad.

Irradiation of the transparent coating composition with active energy rays can be performed in ordinary air, but nitrogen or nitrogen is added so that the atmosphere contains oxygen at a lower concentration than air or does not contain oxygen. It is preferable to carry out the reaction in an atmosphere of an inert gas such as argon or barium.

[0093]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited thereto. In the examples and comparative examples, “parts” indicates “parts by weight”. In addition, the performance evaluation of the coating film,
The following method was used.

[Method for Evaluating Performance of Coating Film] (1) Pencil Scratch Value A pencil scratch value was measured as a value for evaluating the surface hardness of the coating film. That is, JIS K 5400 (199
According to the pencil scratch test specified in 8.4.1 of 5), the coating film was scratched with a pencil lead with a load of 1 kg, and the number of times the coating film was scratched was 2 times in the test 5 times. Among the pencils less than the number of times, the density symbol of the hardest pencil was defined as the pencil scratch value of the coating film.

(2) Scratch Resistance The scratch resistance of the coating film was measured using steel wool (# 0000).
The sample was reciprocated 20 times on the surface of the coating film while applying a load of 500 g / cm ² , and the presence or absence of scratches on the coating film surface was visually evaluated. Then, the case where no scratch was observed on the surface of the coating film was evaluated as “good”, and the case where even a slight scratch was observed on the surface of the coating film was evaluated as “bad”.

(3) Abrasion Resistance The abrasion resistance of the coating film was measured according to JIS K 5400 (1995).
According to the tapered abrasion test specified in 8.9, using a tapered rubber abrasion wheel wound with abrasive paper AA180, applying a 1 kg load while rotating the abrasion wheel at a predetermined rotation speed. Press against membrane, wear wheel 1,000
It was evaluated by measuring the loss of wear per revolution.

(4) Transparency The transparency of the coating film was measured using an MDF plate (Medium Density Fiber Boar).
d; After forming a coating film on the medium fiber board), the sharpness of the pattern of the MDF board is visually confirmed through the coating film. Was evaluated as “semi-transparent” when it was unclear but visible, and as “opaque” when the pattern of the MDF plate was not seen.

Example 1 First, an epoxy resin having an average epoxy equivalent of 185 (trade name "Araltide GY-250") was placed in a four-necked flask equipped with a thermometer, a stirrer, a dropping funnel, an air blowing tube, and a reflux condenser. 2,860 parts, 1,299 methacrylic acid
, 0.62 parts of hydroquinone and 12.5 parts of triethylamine as an ester catalyst. Subsequently, the contents of the flask were placed in an air stream at 115 ° C. for 5.
The mixture was stirred and reacted for 5 hours to obtain an epoxy methacrylate having an acid value of 7.2 as a (meth) acryloyl group-containing resin.

Next, the average particle diameter of the inorganic particles A is 55
15 parts of α-alumina (new Mohs hardness: 12) of μm and crystalline silica (refractive index: 1.553, 1.554, new Mohs hardness of 8) 150 having an average particle diameter of 5 μm as the inorganic particles B
Parts, 55 parts of the above epoxy methacrylate, 45 parts of 1,6-hexanediol dimethacrylate as a (meth) acryloyl group-containing monomer, and a silane coupling agent (trade name “KBM-503”, Shin-Etsu Chemical Co., Ltd.) 0.5 parts) was uniformly mixed with three rolls to obtain a transparent coating composition.

The α-alumina having an average particle diameter of 55 μm has a particle diameter of 5 μm or less, 2% by weight or less, and a particle diameter of 20 μm or less.
m or less was 15% by weight or less, and particles with a particle size of 200 μm or more were 5% by weight or less. In addition, the average particle diameter is 5 μm
The crystalline silica has a particle diameter of 128 μm or more of 0.0
1% by weight or less and particles having a particle size of 24 μm or less accounted for 88% by weight or more. Further, the above epoxy methacrylate 5
The refractive index of the cured resin obtained by curing a mixture consisting of 5 parts and 45 parts of 1,6-hexanediol dimethacrylate was 1.550.

Then, the above-mentioned transparent coating composition was applied using a bar coater to an MDF plate (trade name: “Starwood TFB”, 5.5 mm in thickness, manufactured by Hokusin Co., Ltd.) to which a urethane-based sealer had been previously applied. did. Subsequently, the transparent coating composition was cured by irradiating the transparent coating composition with an electron beam under a nitrogen atmosphere at an acceleration voltage of 200 kV and an irradiation dose of 20 Mrad by an area beam type electron beam irradiation apparatus. Thereby, the film thickness of 60 μm
Was formed on the MDF plate.

The obtained coating film was evaluated for pencil scratch value, scratch resistance, abrasion resistance and transparency by the above-mentioned evaluation methods. Table 2 shows the main composition of the transparent coating composition. Table 3 shows the evaluation results of the coating films.

Example 2 First, an ethylene oxide adduct of bisphenol A (trade name “BPX-11”) was placed in a four-necked flask equipped with a thermometer, a stirrer, a dropping funnel, an air blowing tube and a reflux condenser. (Asahi Denka Kogyo Co., Ltd.)
207 parts and 0.09 part of dibutyltin dilaurate as a urethane catalyst were charged. Subsequently, the internal temperature of the flask was raised to 55 ° C. in an air stream, and 398 parts of 2,4-tolylene diisocyanate was dropped from the dropping funnel. After the completion of the dropping, the mixture was stirred for 1 hour to cause a urethanization reaction.
338 parts of hydroxypropyl methacrylate were charged into the flask. Next, the internal temperature of the flask was raised to 95 ° C., and the mixture was stirred at 95 ° C. for 2 hours to cause a urethanization reaction. Then, disappearance of characteristic absorption of isocyanate groups was confirmed by infrared absorption spectrum (IR). This allows (meta)
Urethane methacrylate as an acryloyl group-containing resin was obtained.

Next, as the inorganic particles A, α-alumina (new Mohs hardness 1) having the same average particle diameter of 55 μm as in Example 1 was used.
2) As inorganic particles B, 15 parts of crystalline silica having the same average particle diameter of 5 μm as in Example 1 (refractive index 1.553, 1.5
54, new Mohs hardness 8) 150 parts, urethane methacrylate 50 parts, 1,6-hexanediol dimethacrylate 5 as a (meth) acryloyl group-containing monomer
0 parts, and a silane coupling agent (trade name “KBM-
503 "(Shin-Etsu Chemical Co., Ltd.) was uniformly mixed with three rolls to obtain a transparent coating composition.

The urethane methacrylate 50 parts and 1,6-hexanediol dimethacrylate 50
When the refractive index of the cured resin obtained by curing the mixture of parts was 1.558.

Then, the above-mentioned transparent coating composition was applied to an MDF plate to which a urethane-based sealer had been previously applied using a bar coater. Then, under a nitrogen atmosphere,
Acceleration voltage 200k by area beam type electron beam irradiation equipment
V, the transparent coating composition was cured by irradiating the transparent coating composition with an electron beam under the conditions of an irradiation dose of 20 Mrad. Thereby, a coating film having a thickness of 60 μm was formed on the MDF plate.

The obtained coating film was evaluated for pencil scratch value, scratch resistance, abrasion resistance and transparency by the above-mentioned evaluation methods. Table 2 shows the main composition of the transparent coating composition. Table 3 shows the evaluation results of the coating films.

Example 3 First, a four-necked flask equipped with a thermometer, a stirrer, a gas inlet, and a reflux condenser was placed in a four-necked flask.
374 parts of neopentyl glycol and 1109 parts of hexahydrophthalic anhydride were charged, and 200 parts
After the temperature was raised to 200 ° C. and the mixture was stirred and reacted at 200 ° C. for 1 hour, the content of the flask was cooled to 115 ° C. when the acid value of the content reached 260. Subsequently, 1048 parts of glycidyl methacrylate, 5.65 parts of zinc octylate as an ester catalyst, and 0.38 part of hydroquinone were added to the flask, and the mixture was stirred and reacted at 115 ° C. for 4 hours in an air stream. . Thus, a polyester methacrylate having an acid value of 1 or less (hereinafter, referred to as polyester methacrylate (A)) was obtained.

Next, as the inorganic particles A, α-alumina (new Mohs hardness 1) having the same average particle size of 55 μm as in Example 1 was used.
2) 15 parts, fused silica having an average particle diameter of 5 μm as inorganic particles B (refractive index 1.4585, new Mohs hardness 7) 15
0 parts, 50 parts of polyester methacrylate (A), 50 parts of 1,9-nonanediol dimethacrylate as a (meth) acryloyl group-containing monomer, and a silane coupling agent (trade name “KBM-503”, Shin-Etsu Chemical Co., Ltd.) (Trade name) (0.5 parts) was uniformly mixed with three rolls to obtain a transparent coating composition.

The fused silica having an average particle size of 5 μm contains particles having a particle size of 128 μm or more in an amount of 0.01% by weight or less,
Particles of 4 μm or less accounted for 90% by weight or more. Further, 50 parts of polyester methacrylate (A) and 1,9-
The refractive index of the cured resin obtained by curing a mixture comprising 50 parts of nonanediol dimethacrylate was 1.462.

Then, the above-mentioned transparent coating composition was applied to an MDF plate to which a urethane-based sealer had been previously applied, using a bar coater. Then, under a nitrogen atmosphere,
Acceleration voltage 200k by area beam type electron beam irradiation equipment
V, the transparent coating composition was cured by irradiating the transparent coating composition with an electron beam under the conditions of an irradiation dose of 20 Mrad. Thereby, a coating film having a thickness of 60 μm was formed on the MDF plate.

The obtained coating film was evaluated for pencil scratch value, scratch resistance, abrasion resistance and transparency by the above-mentioned evaluation methods. Table 2 shows the main composition of the transparent coating composition. Table 3 shows the evaluation results of the coating films.

Example 4 First, a four-necked flask equipped with a thermometer, a stirrer, a gas inlet, and a reflux condenser was charged into a four-necked flask.
766 parts of neopentyl glycol and 940 parts of tetrahydrophthalic anhydride were charged at 215 ° C. in a nitrogen atmosphere.
And stirred at 215 ° C for 5 hours to react.
The solid acid value (acid value of the solid content) of the contents of the flask is 10
When it became, it was cooled to 100 ° C. Subsequently, 130 parts of methacrylic acid and 5 parts of toluene were placed in the flask.
55 parts and 14.0 parts of p-toluenesulfonic acid were charged and subjected to an azeotropic dehydration reaction at 125 ° C. for 12 hours. After the azeotropic dehydration reaction, the solid acid value became 12.0. Furthermore, polyester methacrylate (hereinafter, referred to as polyester methacrylate (B)) was obtained by removing toluene from the reaction system under reduced pressure.

Next, as the inorganic particles A, α-alumina (new Mohs hardness 1) having the same average particle diameter of 55 μm as in Example 1 was used.
2) 15 parts, as inorganic particles B, 150 parts of fused silica (refractive index: 1.4585, new Mohs hardness: 7) having the same average particle diameter of 5 μm as in Example 3, 50 parts of polyester methacrylate (B), (meth) acryloyl group 50 parts of 1,9-nonanediol dimethacrylate as a contained monomer,
And a silane coupling agent (trade name “KBM-50”
3 ", manufactured by Shin-Etsu Chemical Co., Ltd.) was uniformly mixed with 0.5 parts by three rolls to obtain a transparent coating composition.

Incidentally, polyester methacrylate (B) 5
0 parts and 1,9-nonanediol dimethacrylate 5
The refractive index of the cured resin obtained by curing the mixture consisting of 0 parts was 1.467.

Then, the above-mentioned transparent coating composition was applied using a bar coater to an MDF plate to which a urethane-based sealer had been applied in advance. Then, under a nitrogen atmosphere,
Acceleration voltage 200k by area beam type electron beam irradiation equipment
V, the transparent coating composition was cured by irradiating the transparent coating composition with an electron beam under the conditions of an irradiation dose of 20 Mrad. Thereby, a coating film having a thickness of 60 μm was formed on the MDF plate.

The obtained coating film was evaluated for pencil scratch value, scratch resistance, abrasion resistance and transparency by the above-mentioned evaluation methods. Table 2 shows the main composition of the transparent coating composition. Table 3 shows the evaluation results of the coating films.

Example 5 First, as inorganic particles A, 15 parts of α-alumina (new Mohs hardness: 12) having the same average particle diameter of 55 μm as in Example 1, and inorganic particles B as in Example 1
Crystalline silica having the same average particle diameter of 5 μm as above (refractive index 1.5
53, 1.554, new Mohs hardness 8) 150 parts, dimethacrylate of ethylene oxide (EO) adduct of bisphenol A as a (meth) acryloyl group-containing monomer (trade name "Light Ester BP-2EM", 55 parts of Kyoeisha Chemical Co., Ltd. and 45 parts of 1,6-nonanediol dimethacrylate, and a silane coupling agent (trade name "KBM-503", manufactured by Shin-Etsu Chemical Co., Ltd.)
And 0.5 part were uniformly mixed with a three-roll mill to obtain a transparent coating composition.

Incidentally, the refractive index of a cured product obtained by curing a mixture comprising 55 parts of dimethacrylate of the above ethylene oxide (EO) adduct of bisphenol A and 50 parts of 1,6-nonanediol dimethacrylate was measured. However, it was 1.551.

Next, the above-mentioned transparent coating composition was applied to an MDF plate to which a urethane-based sealer had been previously applied, using a bar coater. Subsequently, under a nitrogen atmosphere, an acceleration voltage of 200 k was applied by an area beam type electron beam irradiation apparatus.
V, the transparent coating composition was cured by irradiating the transparent coating composition with an electron beam under the conditions of an irradiation dose of 20 Mrad. Thereby, a coating film having a thickness of 60 μm was formed on the MDF plate.

The obtained coating film was evaluated for pencil scratch value, scratch resistance, abrasion resistance and transparency by the above-mentioned evaluation methods. Table 2 shows the main composition of the transparent coating composition. Table 3 shows the evaluation results of the coating films.

[0122]

[Table 2]

[0123]

[Table 3]

Example 6 First, an epoxy methacrylate as a (meth) acryloyl group-containing resin was obtained by the same reaction and operation as in Example 1. Subsequently, 17 parts of α-alumina (new Mohs hardness: 12) having an average particle diameter of 26 μm as the inorganic particles A and crystalline silica having an average particle diameter of 1.4 μm as the inorganic particles B (refractive index: 1.553, 1.5)
54, new Mohs hardness 8) 100 parts, 55 parts of the above epoxy methacrylate, 1,6-hexanediol methacrylate 45 as a (meth) acryloyl group-containing monomer
Part, and a silane coupling agent (trade name “KBM-5”
03 ", manufactured by Shin-Etsu Chemical Co., Ltd.) was uniformly mixed with three rolls to obtain a transparent coating composition.

The α-alumina having an average particle size of 26 μm has a particle size of 5 μm or less, 5% by weight or less, and a particle size of 20 μm or less.
m or less were 32% by weight or less, and particles with a particle size of 200 μm or more were 2% by weight or less. Further, the average particle diameter is 1.4.
In the crystalline silica having a particle size of μm, particles having a particle size of 128 μm or more were 0.01% by weight or less, and particles having a particle size of 24 μm or less were 99% by weight or more.

Then, the above-mentioned transparent coating composition was applied using a bar coater to an MDF plate to which a urethane sealer had been previously applied. Then, under a nitrogen atmosphere,
Acceleration voltage 200k by area beam type electron beam irradiation equipment
V, the transparent coating composition was cured by irradiating the transparent coating composition with an electron beam under the conditions of an irradiation dose of 20 Mrad. Thereby, a coating film having a thickness of 60 μm was formed on the MDF plate.

The obtained coating film was evaluated for pencil scratch value, scratch resistance, abrasion resistance and transparency by the above-mentioned evaluation methods. Table 4 shows the main composition of the transparent coating composition. Table 5 shows the evaluation results of the coating films.

Comparative Example 1 First, an epoxy methacrylate as a (meth) acryloyl group-containing resin was obtained by the same reaction and operation as in Example 1. Subsequently, 15 parts of α-alumina (new Mohs hardness: 12) having an average particle diameter of 10 μm as inorganic particles A for comparison and crystalline silica having an average particle diameter of 5 μm (refractive index: 1 as in Example 1) as inorganic particles B were used. .553, 1.554, new Mohs hardness 8) 150 parts,
55 parts of the above epoxy methacrylate, 45 parts of 1,6-hexanediol dimethacrylate as a (meth) acryloyl group-containing monomer, and a silane coupling agent (trade name "KBM-503", manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5 part was uniformly mixed with three rolls to obtain a transparent coating composition for comparison.

In the case of α-alumina having an average particle diameter of 10 μm, 40% by weight or more of particles having a particle diameter of 5 μm or less
The particles having a particle size of μm or less were 65% by weight or more.

Next, the above-mentioned transparent paint composition for comparison was applied to an MDF plate to which a urethane-based sealer had been previously applied, using a bar coater. Subsequently, in a nitrogen atmosphere, an accelerating voltage of 20 was applied by an area beam type electron beam irradiation apparatus.
The comparative transparent coating composition was cured by irradiating the comparative transparent coating composition with an electron beam under the conditions of 0 kV and an irradiation dose of 20 Mrad. Thereby, the film thickness of 60 μm
Was formed on the MDF plate.

The obtained coating film was evaluated for pencil scratch value, scratch resistance, abrasion resistance and transparency by the above-mentioned evaluation methods. Table 4 shows the main composition of the comparative transparent coating composition. Table 5 shows the evaluation results of the coating films.

Comparative Example 2 First, an epoxy methacrylate as a (meth) acryloyl group-containing resin was obtained by the same reaction and operation as in Example 1. Subsequently, as inorganic particles A, 15 parts of α-alumina (new Mohs hardness: 12) having the same average particle diameter of 55 μm as in Example 1, and crystalline silica having an average particle diameter of 30 μm as a comparative inorganic particle B (refractive index: 1) .553, 1.554, new Mohs hardness 8) 150 parts,
55 parts of the above epoxy methacrylate, 45 parts of 1,6-hexanediol dimethacrylate as a (meth) acryloyl group-containing monomer, and a silane coupling agent (trade name "KBM-503", manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5 part was uniformly mixed with three rolls to obtain a transparent coating composition for comparison.

In the crystalline silica having an average particle diameter of 30 μm, particles having a particle diameter of 128 μm or more are 7% by weight or more and a particle diameter of 2 μm or more.
Particles having a size of 4 μm or less accounted for 48% by weight or less.

Next, the above-mentioned transparent paint composition for comparison was applied to an MDF plate to which a urethane-based sealer had been previously applied using a bar coater. Subsequently, in a nitrogen atmosphere, an accelerating voltage of 20 was applied by an area beam type electron beam irradiation apparatus.
The comparative transparent coating composition was cured by irradiating the comparative transparent coating composition with an electron beam under the conditions of 0 kV and an irradiation dose of 20 Mrad. Thereby, the film thickness of 60 μm
Was formed on the MDF plate.

The resulting coating film was evaluated for pencil scratch value, scratch resistance, abrasion resistance, and transparency by the above-described evaluation methods. Table 4 shows the main composition of the comparative transparent coating composition. Table 5 shows the evaluation results of the coating films.

Comparative Example 3 First, an epoxy methacrylate as a (meth) acryloyl group-containing resin was obtained by the same reaction and operation as in Example 1. Subsequently, the same average particle diameter of 10 μm as Comparative Example 1 was used as comparative inorganic particles A.
200 parts of α-alumina (new Mohs hardness of 12) and inorganic particles B for comparison, the same average particle size as Comparative Example 2 of 30 μm
m, 20 parts of crystalline silica (refractive index: 1.553, 1.554, new Mohs hardness: 8), 55 parts of the above epoxy methacrylate, 1,6-hexanediol methacrylate 45 as a (meth) acryloyl group-containing monomer Parts, and a silane coupling agent (trade name “KBM-503”,
(Shin-Etsu Chemical Co., Ltd.) 0.5 part was uniformly mixed with three rolls to obtain a transparent coating composition.

Then, the above-mentioned transparent coating composition was applied to an MDF plate to which a urethane sealer had been previously applied, using a bar coater. Then, under a nitrogen atmosphere,
Acceleration voltage 200k by area beam type electron beam irradiation equipment
V, the transparent coating composition was cured by irradiating the transparent coating composition with an electron beam under the conditions of an irradiation dose of 20 Mrad. Thereby, a coating film having a thickness of 60 μm was formed on the MDF plate.

The resulting coating film was evaluated for pencil scratch value, scratch resistance, abrasion resistance, and transparency by the above-mentioned evaluation methods. Table 4 shows the main composition of the transparent coating composition. Table 5 shows the evaluation results of the coating films.

Comparative Example 4 First, an epoxy methacrylate as a (meth) acryloyl group-containing resin was obtained by the same reaction and operation as in Example 1. Subsequently, as inorganic particles A, 15 parts of α-alumina (new Mohs hardness: 12) having the same average particle diameter of 55 μm as in Example 1, and as inorganic particles B, crystalline silica having an average particle diameter of 5 μm as in Example 1 (refractive) Rate 1.553, 1.554, new Mohs hardness 8) 1
50 parts, unsaturated polyester resin (trade name "Epolac NP-160TH", manufactured by Nippon Shokubai Co., Ltd.), (meta)
45 parts of 1,6-hexanediol methacrylate as an acryloyl group-containing monomer and 0.5 part of a silane coupling agent (trade name “KBM-503”, manufactured by Shin-Etsu Chemical Co., Ltd.) are uniformly mixed with three rolls. After mixing, a transparent coating composition was obtained. Table 4 shows the main composition of the transparent coating composition.

The above unsaturated polyester resin contained styrene as a polymerizable monomer and a resin having a fumarate group as a polymerizable double bond (unsaturated polyester).

Then, the above-mentioned transparent coating composition was applied to an MDF plate to which a urethane sealer had been previously applied, using a bar coater. Then, under a nitrogen atmosphere,
Acceleration voltage 200k by area beam type electron beam irradiation equipment
V, the transparent coating composition was irradiated with an electron beam under the conditions of an irradiation dose of 20 Mrad. However, the transparent coating composition did not cure.

[0142]

[Table 4]

[0143]

[Table 5]

[0144]

As described above, the transparent coating composition of the present invention comprises an inorganic particle A having a new Mohs hardness of 10 or more and an average particle diameter in the range of 20 to 200 μm; A has a composition different from that of A, and has a refractive index of 1.40 to 1.
An inorganic particle B having a new Mohs hardness of 5 or more and an average particle diameter of less than 20 μm within a range of 60,
And a monomer having an acryloyl group.

According to the above construction, the transparent coating composition which cures in a short time by irradiation with energy rays and forms a coating film having excellent surface hardness, scratch resistance, abrasion resistance and transparency. Is provided.

Further, as described above, the method for curing the transparent coating composition of the present invention
This is a method of irradiating active energy rays. This allows
This has the effect that the above-mentioned transparent coating composition can be cured in a short time.

──────────────────────────────────────────────────続 き Continued on front page (51) Int.Cl. ⁶ Identification code FI C09D 201/02 C09D 201/02

Claims (5)

[Claims] An inorganic particle A having a new Mohs hardness of 10 or more and an average particle diameter in the range of 20 to 200 μm.
Having a composition different from that of the inorganic particles A, and having a refractive index of 1.40 to
In a range of 1.60, a transparent material comprising: inorganic particles B having a new Mohs hardness of 5 or more and an average particle diameter of less than 20 μm; and a monomer having a (meth) acryloyl group. Paint composition. 2. The transparent coating composition according to claim 1, further comprising a resin having a (meth) acryloyl group. 3. The content of the inorganic particles A is in the range of 1.5 to 17.5% by weight, and the content of the inorganic particles B is 2%.
3. The transparent coating composition according to claim 1, wherein the content is in the range of 3.5 to 65.5% by weight. 4. The resin having a (meth) acryloyl group is an epoxy (meth) acrylate or a urethane (meth).
4. The transparent coating composition according to claim 2, wherein the composition is at least one resin selected from the group consisting of acrylates and polyester (meth) acrylates. 5. A method for curing a transparent coating composition, comprising irradiating the transparent coating composition according to any one of claims 1 to 4 with an active energy ray.