JP7703295B2 - Active energy ray-curable resin composition, active energy ray-curable emulsion composition, coating composition, and urethane (meth)acrylate compound - Google Patents

Description

The present invention relates to an active energy ray-curable resin composition, more specifically, to an active energy ray-curable resin composition which has excellent water dispersibility and which, when coated on a substrate, produces a coating film with excellent hardness and scratch resistance, and to an emulsion composition and a coating composition which use the same. The present invention further relates to a novel urethane (meth)acrylate compound.

Conventionally, urethane (meth)acrylates obtained by reacting diol compounds such as polyester diols and polyether diols, diisocyanate compounds such as isophorone diisocyanate and diphenylmethane diisocyanate, and hydroxyl-containing (meth)acrylates such as hydroxyethyl acrylate are known as active energy ray-curable resins and are used in applications such as woodworking paints and plastic coating agents.

Such urethane (meth)acrylates generally have a high viscosity, and therefore, when used, they are diluted with an organic solvent or a reactive diluent to adjust the viscosity before coating, and then cured by exposure to active energy rays such as ultraviolet light to form a coating film.
However, dilution with the above organic solvents has become problematic in recent years under VOC regulations regarding air pollution, working environment, fire hazards, etc. On the other hand, dilution with a reactive diluent may require a large amount of the reactive diluent to reduce the viscosity, which makes it difficult to obtain sufficient coating film properties.

Under these circumstances, there has been an increasing demand in recent years for water-based compositions such as water-dispersible compositions. For example, Patent Document 1 proposes an aqueous active energy ray-curable resin composition in which a carboxyl group-containing urethane (meth)acrylate is produced in the presence of a water-soluble reactive diluent having a water miscibility of 100% by weight or more, the carboxyl group of the carboxyl group-containing urethane (meth)acrylate is converted into an amine salt, and then water is added to emulsify the resulting composition.

Furthermore, Patent Document 2 proposes a water-dispersed curable resin composition obtained by dispersing at least one curable oligomer selected from urethane acrylate and epoxy acrylate in a water solvent in the presence of a reactive emulsifier.
Furthermore, Patent Document 3 proposes a polyisocyanate derivative in which an isocyanate group in a polyisocyanate compound (a1) forms a urethane bond with a hydroxyl group in a polyalkylene glycol derivative (a2) and with a hydroxyl group in a hydroxyl group-containing (meth)acrylate (a3).

Japanese Patent Application Publication No. 11-279242 JP 2000-159847 A JP 2003-201331 A

However, the technology disclosed in the above Patent Document 1 introduces a carboxyl group into the skeleton of the urethane acrylate, and although it can be made water-based, it does not take into consideration the concentration of acryloyl groups in the urethane acrylate itself, and the surface hardness of the coating film is insufficient. In addition, the technology disclosed in the above Patent Document 1 adds a water-soluble reactive diluent such as acryloylmorpholine to stably emulsify, making it difficult to obtain a coating film with high hardness.

In addition, the technology disclosed in Patent Document 2 requires an emulsifier to disperse in water, and a reactive surfactant having one polymerizable unsaturated group is used as the emulsifier. In most emulsion compositions obtained using such reactive surfactants, the polymerizable unsaturated group of the reactive surfactant is an allyl group or a vinyl group. These allyl groups and vinyl groups have low reactivity and are free in the cured coating film, so when immersed in warm water, the reactive surfactant dissolves in water, which can cause the cured coating film to thin, and is therefore insufficient in terms of coating film hardness and warm water resistance.

The technology disclosed in Patent Document 3 above can make the coating water-based by having a hydrophilic structure derived from a polyalkylene glycol derivative, but with the increasing performance requirements in recent years, there is a demand for coatings that are even more water-based and have excellent surface hardness and scratch resistance.

In light of this background, the present invention aims to provide an active energy ray-curable resin composition that does not require the use of solvents, reactive diluents, or commercially available emulsifiers, is self-emulsifying, has excellent water dispersibility, and further has excellent surface hardness and scratch resistance of the coating film.

However, the present inventors have conducted extensive research in light of these circumstances, and as a result have found that by using an active energy ray-curable resin composition containing a urethane (meth)acrylate compound obtained by reacting a polyisocyanate, a hydroxyl group-containing (meth)acrylate, and a polyalkylene glycol derivative with a carboxyl group-containing polyol, and by making the (meth)acryloyl group concentration of the urethane (meth)acrylate compound relatively high and making the number-average molecular weight of the polyalkylene glycol derivative relatively small, an emulsion with good self-emulsifying properties and post-emulsification stability can be obtained, and a cured coating film with excellent surface hardness and scratch resistance can be formed, thereby completing the present invention.

That is, a first gist of the present invention is an active energy ray-curable resin composition containing a urethane (meth)acrylate compound (A) obtained by reacting a carboxy group-containing polyol (a1), a polyisocyanate compound (a2), a hydroxyl group-containing (meth)acrylate compound (a3), and an alkylene glycol derivative (a4) represented by the following general formula (1), wherein the urethane (meth)acrylate compound (A) has a (meth)acryloyl group concentration of 1 to 10 mmol/g, and the alkylene glycol derivative (a4) has a number average molecular weight of 100 to 20,000.

Furthermore, a second gist of the present invention is an active energy ray-curable emulsion composition obtained by dispersing the above-mentioned active energy ray-curable resin composition in an aqueous solvent, and a third gist of the present invention is a coating agent composition comprising the above-mentioned active energy ray-curable emulsion composition.
A fourth gist of the present invention is a urethane (meth)acrylate compound obtained by reacting a carboxyl group-containing polyol (a1), a polyisocyanate compound (a2), a hydroxyl group-containing (meth)acrylate compound (a3), and an alkylene glycol derivative (a4) represented by the above general formula (1), wherein the (meth)acryloyl group concentration is 1 to 10 mmol/g, and the number average molecular weight of the alkylene glycol derivative (a4) is 100 to 20,000.

The active energy ray curable resin composition of the present invention is an active energy ray curable resin composition containing a urethane (meth)acrylate compound (A) obtained by reacting a carboxyl group-containing polyol (a1), a polyisocyanate compound (a2), a hydroxyl group-containing (meth)acrylate compound (a3) and an alkylene glycol derivative (a4) represented by the above general formula (1), wherein the urethane (meth)acrylate compound (A) has a (meth)acryloyl group concentration of 1 to 10 mmol/g, and the alkylene glycol derivative (a4) has a number average molecular weight of 100 to 20,000. Therefore, it is a self-emulsifying type having excellent water dispersibility, and further has excellent effects in terms of surface hardness and scratch resistance of the coating film, and is very useful as various coating forming materials such as paints, protective coating agents, anchor coating agents, coating agents for hard coats, inks, magnetic powder coating binders, coatings for sandblasting, pressure sensitive adhesives, adhesives, pressure sensitive adhesives, printing plates, etc.
Usually, in order to increase scratch resistance and hardness, one attempts to increase the (meth)acryloyl group concentration of a urethane (meth)acrylate compound, but this ends up decreasing the emulsification suitability instead. In the present invention, however, by containing both a structural portion derived from a polyol containing a carboxy group and a structural portion derived from a specific alkylene glycol derivative, it is possible to obtain an active energy ray-curable resin composition that satisfactorily satisfies these conflicting physical properties.

Hereinafter, the embodiments of the present invention will be described in detail, but the present invention is not limited to these.
In the present invention, "(meth)acrylic" means acrylic or methacrylic, "(meth)acryloyl" means acryloyl or methacryloyl, and "(meth)acrylate" means acrylate or methacrylate, respectively.

The active energy ray-curable resin composition of the present invention contains a specific urethane (meth)acrylate compound (A) that can be dispersed in an aqueous solvent. Each of the components will be described below.

[Urethane (meth)acrylate compound (A)]
The urethane (meth)acrylate compound (A) has a higher (meth)acryloyl group concentration than ordinary water-dispersible urethane (meth)acrylates, and the chain length of the hydrophilic group contained in its molecular structure is relatively short.
The urethane (meth)acrylate compound (A) is obtained by reacting a carboxyl group-containing polyol (a1), a polyisocyanate compound (a2), a hydroxyl group-containing (meth)acrylate compound (a3), and an alkylene glycol derivative (a4) having a specific number average molecular weight.

[Polyol (a1) containing a carboxy group]
The molecular weight of the polyol (a1) containing a carboxy group (hereinafter sometimes simply referred to as "carboxy group-containing polyol") is preferably 100-200, more preferably 110-180, and particularly preferably 120-160.

Examples of the carboxyl group-containing polyol (a1) include aliphatic polyhydroxycarboxylic acids and aromatic polyhydroxycarboxylic acids, and preferably aliphatic polyhydroxycarboxylic acids.

Examples of the aliphatic polyhydroxycarboxylic acid include diol monocarboxylic acids such as dimethylolbutanoic acid, dimethylolpropionic acid, glyceric acid, mevalonic acid, and pantoic acid, diol dicarboxylic acids such as tartaric acid, triol monocarboxylic acids such as shikimic acid, and tetraol monocarboxylic acids such as quinic acid. These can be used alone or in combination of two or more. The carboxy group-containing polyol (a1) may be a neutralized product of the polyhydroxycarboxylic acid, particularly a neutralized product of an aliphatic polyhydroxycarboxylic acid.

As the carboxyl group-containing polyol (a1), from the viewpoint of self-emulsifying property, an aliphatic polyhydroxycarboxylic acid is preferable, more preferably a diol monocarboxylic acid having a molecular weight of 100 to 200 or a neutralized salt thereof, and particularly preferably dimethylolbutanoic acid or dimethylolpropionic acid. Furthermore, from the viewpoint of the balance between the time required for the reaction during production and the pencil hardness of the cured coating film, it is preferable to use two or more diol monocarboxylic acids in combination, and it is particularly preferable to use dimethylolbutanoic acid and dimethylolpropionic acid in combination.

[Polyisocyanate compound (a2)]
Examples of the polyisocyanate compound (a2) include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, polyphenylmethane polyisocyanate, modified diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, phenylene diisocyanate, and naphthalene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexamethylene diisocyanate. Examples of the polyisocyanate compound (a2) include aliphatic polyisocyanates such as diisocyanate, lysine diisocyanate, and lysine triisocyanate, alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, and norbornene diisocyanate, or trimer compounds or oligomer compounds of these polyisocyanates, allophanate polyisocyanates, biuret polyisocyanates, and water-dispersible polyisocyanates. These polyisocyanate compounds (a2) can be used alone or in combination of two or more kinds.

The polyisocyanate-based compound (a2) may be a reaction product between various polyols, such as low molecular weight polyols and high molecular weight polyols, particularly polyether-based polyols, polyester-based polyols, polycarbonate-based polyols, polyolefin-based polyols, polybutadiene-based polyols, and (meth)acrylic polyols, and a polyisocyanate-based compound.

Among these, in terms of excellent reactivity and versatility, aliphatic diisocyanates such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate, and alicyclic diisocyanates such as hydrogenated diphenylmethane diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, and norbornene diisocyanate are preferred, with alicyclic diisocyanates being particularly preferred, and isophorone diisocyanate and hydrogenated xylylene diisocyanate being even more preferred, with isophorone diisocyanate being particularly preferred.

[Hydroxyl group-containing (meth)acrylate compound (a3)]
Examples of the hydroxyl group-containing (meth)acrylate compound (a3) include hydroxyalkyl (meth)acrylates having an alkyl group with 1 to 16 (preferably 1 to 12) carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate; compounds having one (meth)acryloyl group, such as 2-hydroxyethyl acryloyl phosphate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, caprolactone-modified 2-hydroxyethyl (meth)acrylate, and fatty acid-modified glycidyl (meth)acrylate (wherein Y in the following general formula (1) described later is (meth)acryloyl). (excluding polyalkylene glycol derivatives (a4) which are 1-hydroxyl groups); compounds having two (meth)acryloyl groups such as glycerin di(meth)acrylate and 2-hydroxy-3-acryloyl-oxypropyl(meth)acrylate; compounds having three or more (meth)acryloyl groups such as pentaerythritol tri(meth)acrylate, caprolactone-modified pentaerythritol tri(meth)acrylate, ethylene oxide-modified pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, caprolactone-modified dipentaerythritol penta(meth)acrylate, ethylene oxide-modified dipentaerythritol penta(meth)acrylate, and succinic acid-modified pentaerythritol tri(meth)acrylate. These may be used alone or in combination of two or more.

Among these, hydroxyl-containing (meth)acrylates having two or more (meth)acryloyl groups in the molecule are preferred, from the viewpoint of obtaining a cured coating film with high hardness, more preferably hydroxyl-containing (meth)acrylates having three or more (meth)acryloyl groups in the molecule, particularly preferably pentaerythritol tri(meth)acrylate and dipentaerythritol penta(meth)acrylate, and even more preferably dipentaerythritol penta(meth)acrylate.

[Alkylene glycol derivative (a4)]
The alkylene glycol derivative (a4) may have a structure represented by the following general formula (1), and examples thereof include those in which both terminals are hydroxyl groups, or the hydrogen of the hydroxyl group at one terminal is substituted with any one of an alkyl group, an alkylphenyl group, a (meth)acryloyl group, an allyl group, and an acyl group.

Specific examples of the alkylene glycol derivative (a4) in which Y in the above general formula (1) is hydrogen include polyalkylene glycols having an oxyalkylene structure, such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polybutylene glycol, and polyhexamethylene glycol, and linear polyether polyols such as random or block copolymers of these polyalkylene glycols.

Specific examples of alkylene glycol derivatives (a4) in which Y in the above general formula (1) is an alkyl group or an alkylphenyl group include, for example, polyethylene glycol monomethyl ether, polyethylene glycol lauryl ether, polyethylene glycol cetyl ether, polyethylene glycol stearyl ether, polyethylene glycol nonylphenyl ether, polyethylene glycol tridecyl ether, polyethylene glycol oleyl ether, polyethylene glycol octylphenyl ether, polyoxyethylene oleyl cetyl ether, and polypropylene glycol monomethyl ether.

Specific examples of the alkylene glycol derivative (a4) in which Y in the above general formula (1) is a (meth)acryloyl group include polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, poly(ethylene glycol-propylene glycol) mono(meth)acrylate, poly(ethylene glycol-tetramethylene glycol) mono(meth)acrylate, poly(propylene glycol-tetramethylene glycol) mono(meth)acrylate, etc.

Specific examples of the alkylene glycol derivative (a4) in which Y in the above general formula (1) is an allyl group include polyethylene glycol monoallyl ether, polypropylene glycol monoallyl ether, poly(ethylene glycol-propylene glycol) monoallyl ether, etc.

Specific examples of the alkylene glycol derivative (a4) in which Y in the above general formula (1) is an acyl group include polyethylene glycol monolaurate, polypropylene glycol monolaurate, poly(ethylene glycol-propylene glycol) monolaurate, polyethylene glycol monostearate, and polyethylene glycol monooleate.

Among the above, from the viewpoint of hydrophilicity, polyethylene glycol derivatives are preferred, and the repeat number n of ethylene oxide addition is more preferably 2 to 300, particularly 4 to 100, and further preferably 6 to 50. Furthermore, from the viewpoint of emulsifiability, it is particularly preferred that Y is hydrogen.
The alkylene glycol derivatives (a4) may be used alone or in combination of two or more kinds.

The number average molecular weight of the alkylene glycol derivative (a4) is 100 to 20,000. It is preferably 150 to 5,000, more preferably 200 to 2,000, and particularly preferably 300 to 950. If the number average molecular weight is too small, self-emulsification becomes difficult, and if the number average molecular weight is too large, the water resistance and hardness of the cured coating film decrease.

Furthermore, the hydroxyl value of the alkylene glycol derivative (a4) is preferably 20 to 500 mgKOH/g, particularly preferably 50 to 400 mgKOH/g, and even more preferably 100 to 300 mgKOH/g. If the hydroxyl value is too low, the water resistance and hardness of the cured coating film tend to decrease, and if it is too high, self-emulsification tends to become difficult.

[Method for producing urethane (meth)acrylate compound (A)]
The urethane (meth)acrylate compound (A) used in the present invention can be obtained by reacting a carboxy group-containing polyol (a1), a polyisocyanate compound (a2), a hydroxyl group-containing (meth)acrylate compound (a3), and an alkylene glycol derivative (a4) having a specific number average molecular weight.

The proportions of the above components (a1) to (a4) when reacting are as follows: the proportion of the carboxyl-containing polyol (a1) is preferably 0.1 to 20% by weight, more preferably 0.5 to 10% by weight, and particularly preferably 1 to 5% by weight, the proportion of the polyisocyanate compound (a2) is preferably 1 to 80% by weight, more preferably 5 to 40% by weight, and particularly preferably 7 to 25% by weight, the proportion of the hydroxyl-containing (meth)acrylate compound (a3) is preferably 10 to 95% by weight, more preferably 30 to 90% by weight, and particularly preferably 50 to 85% by weight, and the proportion of the alkylene glycol derivative (a4) is preferably 1 to 80% by weight, more preferably 3 to 50% by weight, and particularly preferably 5 to 20% by weight, relative to the total of the carboxyl-containing polyol (a1), the polyisocyanate compound (a2), the hydroxyl-containing (meth)acrylate compound (a3), and the alkylene glycol derivative (a4). If the ratio of components (a1) to (a4) is outside the above range, the emulsifiability of the resulting urethane (meth)acrylate compound (A) and the hardness of the cured coating film tend to decrease.

In the present invention, the ratio (weight ratio) of the carboxyl group-containing polyol (a1) and the alkylene glycol derivative (a4) that constitute the polyol component is preferably 1/99 to 95/5 in terms of emulsifiability, more preferably 3/97 to 50/50, and particularly preferably 5/95 to 30/70.

The method for obtaining the urethane (meth)acrylate compound (A) using the above (a1) to (a4) is not particularly limited, and for example,
(i) A method in which a carboxyl group-containing polyol (a1), a polyisocyanate compound (a2), a hydroxyl group-containing (meth)acrylate compound (a3) and an alkylene glycol derivative (a4) are charged at once and reacted;
(ii) A method in which a polyisocyanate compound (a2), a hydroxyl group-containing (meth)acrylate compound (a3), a carboxyl group-containing polyol (a1) and an alkylene glycol derivative (a4) are sequentially charged and reacted;
(iii) A method in which a polyisocyanate compound (a2), a carboxyl group-containing polyol (a1), a hydroxyl group-containing (meth)acrylate compound (a3) and an alkylene glycol derivative (a4) are sequentially charged and reacted;
(iv) A method in which a polyisocyanate compound (a2), an alkylene glycol derivative (a4), a carboxyl group-containing polyol (a1), and a hydroxyl group-containing (meth)acrylate compound (a3) are sequentially charged and reacted;
etc.
Among these, methods (ii) and (iii) are preferred from the viewpoint of stability of reaction control, and method (ii) is particularly preferred.

In addition, in the above reaction, it is preferable to use a catalyst to promote the reaction. Examples of such catalysts include organometallic compounds such as dibutyltin dilaurate, dibutyltin diacetate, trimethyltin hydroxide, tetra-n-butyltin, zinc bisacetylacetonate, zirconium tris(acetylacetonate)ethylacetoacetate, and zirconium tetraacetylacetonate; metal salts such as tin octoate, tin octenate, zinc hexanoate, zinc octenate, zinc stearate, zirconium 2-ethylhexanoate, cobalt naphthenate, stannous chloride, stannous chloride, and potassium acetate; triethylamine, triethylenediamine, benzyldiethylamine, 1,4-diazabicyclo[2,2,2]octane, 1,8-diazabicyclo[2,2,2]octane, and the like. Examples of the bismuth catalyst include amine catalysts such as chloro[5,4,0]undecene, N,N,N',N'-tetramethyl-1,3-butanediamine, N-methylmorpholine, and N-ethylmorpholine, bismuth nitrate, bismuth bromide, bismuth iodide, and bismuth sulfide, as well as organic bismuth compounds such as dibutyl bismuth dilaurate and dioctyl bismuth dilaurate, and organic acid bismuth salts such as bismuth 2-ethylhexanoate, bismuth naphthenate, bismuth isodecanoate, bismuth neodecanoate, bismuth laurate, bismuth maleate, bismuth stearate, bismuth oleate, bismuth linoleate, bismuth acetate, bismuth tribisneodecanoate, bismuth disalicylate, and bismuth digallate. Among these, dibutyltin dilaurate and 1,8-diazabicyclo[5,4,0]undecene are preferred. These can be used alone or in combination of two or more types.

Furthermore, in the above reaction, it is preferable to use a polymerization inhibitor.
As the polymerization inhibitor, a known general one used as a polymerization inhibitor can be used, and examples thereof include quinones such as p-benzoquinone, naphthoquinone, toluquinone, and 2,5-diphenyl-p-benzoquinone, and phenols such as hydroquinone, 2,5-di-t-butylhydroquinone, methylhydroquinone, hydroquinone monomethyl ether, mono-t-butylhydroquinone, 2,6-di-t-butylcresol, and p-t-butylcatechol. Among these, phenols are preferred, and 2,6-di-t-butylcresol is particularly preferred. These can be used alone or in combination of two or more kinds.

The reaction temperature is usually 30 to 100°C, preferably 40 to 90°C, and the reaction time is usually 2 to 30 hours, preferably 3 to 20 hours.

Thus, the urethane (meth)acrylate compound (A) is obtained.

The (meth)acryloyl group concentration of the urethane (meth)acrylate compound (A) is 1 to 10 mmol/g. It is preferably 3 to 9 mmol/g, and particularly preferably 5 to 8 mmol/g. If the (meth)acryloyl group concentration is too low, the hardness of the cured coating film decreases, and if the (meth)acryloyl group concentration is too high, the emulsifiability decreases.

The weight average molecular weight of the urethane (meth)acrylate compound (A) is usually 1,500 to 30,000, preferably 1,700 to 10,000, and particularly preferably 2,000 to 5,000.
If the weight average molecular weight is too small, the emulsifiability tends to decrease, whereas if it is too large, the viscosity tends to become high and handling tends to become difficult.

In the present invention, the weight average molecular weight is the weight average molecular weight converted into the standard polystyrene molecular weight, and is measured using a high performance liquid chromatograph (manufactured by Waters, "ACQUITY APC System") with four columns in series: one ACQUITY APC XT 450, one ACQUITY APC XT 200, and two ACQUITY APC XT 45.

The viscosity of the urethane (meth)acrylate compound (A) at 60° C. is usually 1,000 to 300,000 mPa·s, preferably 1,200 to 100,000 mPa·s, and particularly preferably 1,500 to 50,000 mPa·s. If the viscosity is outside the above range, the coatability tends to decrease.
The viscosity is measured using an E-type viscometer.

The acid value of the urethane (meth)acrylate compound (A) is preferably 1 to 40 mgKOH/g, more preferably 3 to 30 mgKOH/g, and particularly preferably 5 to 20 mgKOH/g. If the acid value of the urethane (meth)acrylate compound (A) is too low, the emulsifiability decreases, whereas if the acid value is too high, the viscosity increases, making it difficult to handle, and the hardness of the cured coating film decreases.
The acid value can be determined by a method in accordance with JIS K0070.

In addition, from the viewpoint of emulsifiability, it is also preferable to use a neutralized product of the urethane (meth)acrylate compound (A) obtained by neutralizing the urethane (meth)acrylate compound (A).

Examples of bases used for the neutralization include ammonia, trimethylamine, triethylamine, methyldiethanolamine, dimethylethanolamine, diethylethanolamine, triethanolamine, potassium hydroxide, sodium hydroxide, etc., and these bases are usually used as aqueous solutions. Among these, aqueous ammonia solutions are preferred in terms of drying properties and versatility.

The amount of the base used is usually 0.5 to 2 molar equivalents, preferably 0.8 to 1.5 molar equivalents, per 1 molar equivalent of carboxylic acid contained in the urethane (meth)acrylate compound (A). If the amount of the base used is outside the above range, the emulsifiability of the neutralized product of the urethane (meth)acrylate compound (A) tends to decrease.

The pH of the neutralized product of the urethane (meth)acrylate compound (A) is usually 7 to 14, and preferably 8 to 12. If the pH is outside the above range, the emulsifiability and emulsion stability of the neutralized product of the urethane (meth)acrylate compound (A) tend to decrease.

The active energy ray-curable resin composition of the present invention contains the above-mentioned urethane (meth)acrylate compound (A) or its neutralized product, preferably a photopolymerization initiator (B), an ethylenically unsaturated monomer (C), and, if necessary, a urethane (meth)acrylate compound other than the urethane (meth)acrylate compound (A) and other components.

[Photopolymerization initiator (B)]
The active energy ray-curable resin composition of the present invention preferably contains a photopolymerization initiator (B) from the viewpoint of promoting curing when irradiated with active energy rays. The photopolymerization initiator (B) may be used alone or in combination of two or more kinds.

The photopolymerization initiator (B) is not particularly limited as long as it generates radicals by the action of light, and examples thereof include 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-(4-isopropylenephenyl)-2-hydroxy-2-methylpropan-1-one, 1-(4-dodecylphenyl)-2-hydroxy-2-methylpropan-1-one, 4-(2-hydroxyethoxy)-phenyl nyl(2-hydroxy-2-propyl)ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyl dimethyl ketal, benzophenone, benzoylbenzoic acid, benzoylbenzoic acid methyl, 4-phenylbenzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl Diphenyl sulfide, 3,3'-dimethyl-4-methoxybenzophenone, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, camphorquinone, dibenzosuberone, 2-ethylanthraquinone, 4',4''-diethylisophthalophenone, 3,3',4,4'-tetra(t-butylperoxycarbonyl)benzophenone, α-acyloxime ester, acylphosphine oxide, methylphenylglyoxy ester, benzil, 9,10-phenanthrenequinone, 4-(2-hydroxyethoxy)phenyl-(2-hydroxy-2-propyl)ketone, etc., among which benzil dimethyl ketal, 1-hydroxycyclohexyl phenyl ketone, benzoin isopropyl ether, 4-(2-hydroxyethoxy)-phenyl(2-hydroxy-2-propyl)ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one are preferred, and 1-hydroxycyclohexyl phenyl ketone is particularly preferred.

In addition, when the active energy ray-curable resin composition of the present invention is dispersed in an aqueous solvent to form an active energy ray-curable emulsion composition, a water-soluble or water-dispersible photopolymerization initiator may be used in order to further exhibit its functions.
Examples of the water-soluble or water-dispersible photopolymerization initiator include 2-(3-dimethylamino-2-hydroxypropoxy)-3,4-dimethyl-9H-thioxanthone-9-one methochloride (manufactured by Octel Chemicals, "Quantacure QTX") and 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one (manufactured by IGM Resins, "Omnirad 2959"), among which 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one is preferred.

The amount of the photopolymerization initiator (B) is preferably 0.01 to 10 parts by weight, particularly preferably 0.1 to 5 parts by weight, per 100 parts by weight of the urethane (meth)acrylate compound (A) (in the case of containing an ethylenically unsaturated monomer (C) described below, per 100 parts by weight of the total of the urethane (meth)acrylate compound (A) and the ethylenically unsaturated monomer (C)). If the amount is too small, the curing speed tends to decrease or the curing tends to be insufficient, and if the amount is too large, the curability does not improve and the economic efficiency tends to decrease.

In addition, as an auxiliary for the photopolymerization initiator (B), for example, triethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone (Michler's ketone), 4,4'-diethylaminobenzophenone, 2-dimethylaminoethylbenzoic acid, ethyl 4-dimethylaminobenzoate, (n-butoxy)ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, etc. may be used in combination.

[Ethylenically unsaturated monomer (C)]
The ethylenically unsaturated monomer (C) may be any monomer having one or more ethylenically unsaturated groups in one molecule, and may be a monofunctional monomer, a bifunctional monomer, or a trifunctional or higher monomer. The ethylenically unsaturated monomer (C) may be used alone or in combination of two or more kinds.

Examples of the monofunctional monomers include styrene, vinyl toluene, chlorostyrene, α-methylstyrene, methyl (meth)acrylate, ethyl (meth)acrylate, acrylonitrile, vinyl acetate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, phenoxyethyl (meth)acrylate, 2-phenoxy-2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, glycerin mono(meth)acrylate, glycidyl (meth)acrylate, lauryl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, tricyclodecanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, n-butyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, ) acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, dodecyl (meth)acrylate, n-stearyl (meth)acrylate, benzyl (meth)acrylate, phenol ethylene oxide modified (meth)acrylate, nonylphenol propylene oxide modified (meth)acrylate, half ester (meth)acrylate of phthalic acid derivative such as 2-(meth)acryloyloxy-2-hydroxypropyl phthalate, furfuryl (meth)acrylate, carbitol (meth)acrylate, benzyl (meth)acrylate, butoxyethyl (meth)acrylate, allyl (meth)acrylate, acryloylmorpholine, 2-hydroxyethyl acrylamide, N-methylol (meth)acrylamide, N-vinylpyrrolidone, 2-vinylpyridine, 2-(meth)acryloyloxyethyl acid phosphate monoester, and the like.

In addition to the above, the monofunctional monomer may also be a Michael adduct of acrylic acid or a 2-acryloyloxyethyl dicarboxylic acid monoester. Examples of the Michael adduct of acrylic acid include acrylic acid dimer, methacrylic acid dimer, acrylic acid trimer, methacrylic acid trimer, acrylic acid tetramer, and methacrylic acid tetramer. Examples of 2-acryloyloxyethyl dicarboxylic acid monoester, which is a carboxylic acid having a specific substituent, include, for example, 2-acryloyloxyethyl succinic acid monoester, 2-methacryloyloxyethyl succinic acid monoester, 2-acryloyloxyethyl phthalic acid monoester, 2-methacryloyloxyethyl phthalic acid monoester, 2-acryloyloxyethyl hexahydrophthalic acid monoester, and 2-methacryloyloxyethyl hexahydrophthalic acid monoester. Oligoester acrylates may also be used.

Examples of the bifunctional monomers include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, ethylene oxide modified bisphenol A type di(meth)acrylate, propylene oxide modified bisphenol A type di(meth)acrylate, 1 ,6-hexanediol di(meth)acrylate, 1,6-hexanediol ethylene oxide modified di(meth)acrylate, glycerin di(meth)acrylate, pentaerythritol di(meth)acrylate, ethylene glycol diglycidyl ether di(meth)acrylate, diethylene glycol diglycidyl ether di(meth)acrylate, phthalic acid diglycidyl ester di(meth)acrylate, hydroxypivalic acid modified neopentyl glycol di(meth)acrylate, isocyanuric acid ethylene oxide modified diacrylate, 2-(meth)acryloyloxyethyl acid phosphate diester, etc.

Examples of the trifunctional or higher monomers include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tri(meth)acryloyloxyethoxytrimethylolpropane, glycerin polyglycidyl ether poly(meth)acrylate, isocyanuric acid ethylene oxide modified triacrylate, ethylene oxide modified dipentaerythritol penta(meth)acrylate, ethylene oxide modified dipentaerythritol hexa(meth)acrylate, ethylene oxide modified pentaerythritol tri(meth)acrylate, ethylene oxide modified pentaerythritol tetra(meth)acrylate, succinic acid modified pentaerythritol tri(meth)acrylate, etc.

In the present invention, ethylenically unsaturated monomers having water-solubility or water-dispersibility may be used in terms of emulsion stability and compatibility with the resin.
Examples of the ethylenically unsaturated monomer having water-solubility or water-dispersibility include acryloyl morpholine, polyethylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ethylene oxide-modified pentaerythritol tetraacrylate, isocyanuric acid ethylene oxide-modified diacrylate, isocyanuric acid ethylene oxide-modified triacrylate, ethylene oxide-modified epoxy acrylate, polyester acrylate mainly composed of polyethylene glycol, etc. Among them, acryloyl morpholine, polyethylene glycol diacrylate, isocyanuric acid ethylene oxide-modified diacrylate, isocyanuric acid ethylene oxide-modified triacrylate, etc. are preferred.

The amount of the ethylenically unsaturated monomer (C) is preferably 500 parts by weight or less, more preferably 300 parts by weight or less, and particularly preferably 100 parts by weight or less, per 100 parts by weight of the urethane (meth)acrylate compound (A). If the amount used is too large, the hardness of the cured coating film tends to decrease, and the emulsifiability also tends to decrease.

[Other ingredients]
Furthermore, the active energy ray-curable resin composition of the present invention may contain, as necessary, an emulsifier (surfactant), a filler, a dye or pigment, an oil, a plasticizer, a wax, a drying agent, a dispersant, a wetting agent, a gelling agent, a stabilizer, an antifoaming agent, a leveling agent, a thixotropy-imparting agent, an antioxidant, a flame retardant, an antistatic agent, a filler, a reinforcing agent, a matting agent, a crosslinking agent, silica, water-dispersed silica, a preservative, and the like.

The active energy ray curable resin composition of the present invention contains a urethane (meth)acrylate compound (A) or a neutralized product thereof. The urethane (meth)acrylate compound (A) or a neutralized product thereof has a structural portion derived from a hydrophobic polyisocyanate compound (a2) and a hydroxyl group-containing (meth)acrylate compound (a3), and a structural portion derived from a hydrophilic carboxyl group-containing polyol (a1) and an alkylene glycol derivative (a4), and therefore has self-emulsifying properties. Therefore, it can be dispersed in an aqueous solvent, and by dispersing the active energy ray curable resin composition of the present invention in an aqueous solvent, an active energy ray curable emulsion composition can be obtained.

In the present invention, "self-emulsifying" means the property of emulsifying by itself upon contact with an aqueous solvent without the need for shear force or the like during emulsification.

The active energy ray curable emulsion composition of the present invention, for example, is an aqueous dispersion of the active energy ray curable resin composition at a concentration of 30% by weight, and even after being left to stand at room temperature (23°C) for two weeks, no precipitation is observed and the emulsion composition can maintain a uniformly dispersed state.

The active energy ray-curable emulsion composition is described below.

The active energy ray-curable emulsion composition of the present invention can be obtained by the following emulsification method.
The emulsification method is, for example,
(1) A method in which the urethane (meth)acrylate compound (A) or a neutralized product thereof and an aqueous solvent are charged at once and stirred usually at 30 to 80° C., preferably 45 to 65° C.;
(2) A method in which an aqueous solvent is added dropwise to the urethane (meth)acrylate compound (A) or its neutralized product while stirring the compound at a temperature of usually 30 to 80° C., preferably 45 to 65° C.;
(3) A method in which the urethane (meth)acrylate compound (A) or a neutralized product thereof is added dropwise to an aqueous solvent while stirring the aqueous solvent at a temperature of usually 30 to 80° C., preferably 45 to 65° C.;
etc.
Among these, the method (2) is preferred since it is possible to obtain a uniform emulsion.

When the photopolymerization initiator (B), the ethylenically unsaturated monomer (C), and other components are mixed, the urethane (meth)acrylate compound (A) or its neutralizer, the photopolymerization initiator (B), the ethylenically unsaturated monomer (C), and other components may be mixed in advance and then emulsified by stirring, or the urethane (meth)acrylate compound (A) or its neutralizer and an aqueous solvent may be emulsified, and then the photopolymerization initiator (B), the ethylenically unsaturated monomer (C), and other components may be mixed. However, the method of mixing the photopolymerization initiator (B), the ethylenically unsaturated monomer (C), and other components is not limited to these methods.

The aqueous solvent is not limited to water, but may be a mixture of water and a lower alcohol having 1 to 5 carbon atoms, as long as the emulsion state is not impaired.

The amount of aqueous solvent used is preferably 5 to 95% by weight of the entire active energy ray-curable emulsion composition, particularly preferably 10 to 80% by weight, and even more preferably 20 to 60% by weight. If the amount of aqueous solvent used is too small, the viscosity tends to be too high, and if it is too large, the drying load during coating tends to be large.

From the viewpoint of ease of application, the non-volatile content of the obtained active energy ray-curable emulsion composition is preferably 5 to 80% by weight, more preferably 10 to 70% by weight, and even more preferably 20 to 60% by weight. If the non-volatile content is too low, repelling tends to occur on the substrate during application and the drying load tends to be large, whereas if the non-volatile content is too high, the fluidity tends to be low, making application difficult.

The particles of the urethane (meth)acrylate compound (A) or its neutralized product in the obtained active energy ray-curable emulsion composition preferably have an average particle size of 1 to 1,000 nm, particularly preferably 10 to 500 nm, and even more preferably 20 to 200 nm. If the average particle size is too small, the emulsion viscosity tends to increase and become difficult to handle, whereas if the average particle size is too large, aggregation tends to occur and emulsion stability tends to decrease. The average particle size referred to here refers to the average particle size value of the scattering intensity distribution.

Furthermore, the viscosity of the active energy ray-curable emulsion composition is preferably 5 to 20,000 mPa·s (20°C), particularly 10 to 10,000 mPa·s (20°C), and more preferably 20 to 5,000 mPa·s (20°C). If the viscosity is too low, it tends to be difficult to control the film thickness, and if it is too high, it tends to be difficult to handle and the coating workability tends to decrease. The viscosity is measured using an E-type viscometer.

The active energy ray-curable emulsion composition may further contain freeze-thaw stabilizers such as ethylene glycol, other emulsions, film-forming agents such as butyl cellosolve, polar solvents for aiding water dispersion such as N-methylpyrrolidone and 3-methoxy-N,N-dimethylpropionamide, etc., within the scope of not impairing the effects of the present invention. These may be used alone or in combination of two or more kinds.

The active energy ray-curable emulsion composition is applied to a substrate, dried, and then cured by irradiating the substrate with active energy rays.

Examples of substrates to which the active energy ray-curable emulsion composition of the present invention is applied include plastic substrates such as polyolefin resins, polyester resins, polycarbonate resins, acrylonitrile-butadiene-styrene copolymers (ABS), polystyrene resins, acrylic resins, and molded products thereof (films, sheets, cups, etc.), optical films such as polyethylene terephthalate films, triacetyl cellulose films, and cycloolefin films, composite substrates thereof, composite substrates of the above materials mixed with glass fibers or inorganic substances, metals (aluminum, copper, iron, SUS, zinc, magnesium, alloys thereof, etc.), glass, wood, paper, and substrates having a primer layer formed on the above substrates.

Examples of the method for applying the active energy ray-curable emulsion composition of the present invention include wet coating methods such as spraying, showering, gravure, dipping, rolling, spinning, and screen printing. Usually, the composition is applied to a substrate at room temperature (particularly in a temperature range where no heating is performed).

The drying conditions are generally a temperature of 40 to 120°C, preferably 50 to 100°C, and a drying time of generally 1 to 20 minutes, preferably 2 to 10 minutes.

Examples of active energy rays that can be used when curing the active energy ray-curable emulsion composition applied to a substrate include light rays such as far ultraviolet rays, ultraviolet rays, near ultraviolet rays, and infrared rays; electromagnetic waves such as X-rays and γ-rays; and electron beams, proton beams, and neutron beams. From the viewpoints of curing speed, availability of an irradiation device, cost, and the like, ultraviolet rays or electron beams, particularly ultraviolet rays, are preferred.
When the curing is carried out by irradiation with an electron beam, the curing can be carried out without using the photopolymerization initiator (B).

When curing by irradiation with ultraviolet rays, ultraviolet rays of typically 30 to 3,000 mJ/cm2, preferably 100 to 1,500 mJ/ ^cm2 may be irradiated using a high-pressure mercury lamp, ultra-high-pressure mercury lamp, carbon arc lamp, metal halide lamp, xenon lamp, chemical lamp, electrodeless discharge lamp, LED lamp, or the like that emits light in the wavelength range of ¹⁵⁰ to 450 nm.
After the ultraviolet irradiation, heating may be carried out as necessary to ensure complete curing.

The coating thickness (film thickness after curing) is usually 1 to 1,000 μm, preferably 2 to 500 μm, and particularly preferably 3 to 200 μm, in order to transmit light so that the photopolymerization initiator reacts uniformly as an active energy ray-curable coating.

The active energy ray-curable emulsion composition of the present invention is useful as a material for forming various coatings, such as paints, protective coatings, anchor coatings, hard coat coatings, inks, magnetic powder coating binders, sandblasting coatings, pressure sensitive adhesives, adhesives, tackifiers, printing plates, etc.

The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to the following examples as long as it does not deviate from the gist of the invention. In the examples, "parts" and "%" are by weight.

Prior to the examples, the following urethane (meth)acrylate compounds were prepared.

[Preparation of urethane acrylate compound (A-1)]
Into a flask equipped with an internal thermometer, a stirrer, and a cooling tube, 103 g (0.465 mol) of isophorone diisocyanate, 653 g (0.558 mol) of an acrylic acid adduct of dipentaerythritol [hydroxyl value: 48.0 mgKOH/g], 1.65 g of 2,6-di-t-butylcresol as a polymerization inhibitor, and 0.1 g of dibutyltin dilaurate as a reaction catalyst were added and reacted at 70° C. When the residual isocyanate groups reached 2.1% or less, 3.45 g (0.023 mol) of dimethylolbutanoic acid and 9.36 g (0.070 mol) of dimethylolpropionic acid were added and reacted at 90° C. When the residual isocyanate groups reached 1.0% or less, the mixture was cooled to 60°C, and 231 g (0.233 mol) of polyethylene glycol (hydroxyl value: 113.0 mgKOH/g, number average molecular weight calculated from the hydroxyl value: 993) was added and reacted at 60°C. The reaction was terminated when the residual isocyanate groups reached 0.1% or less, thereby obtaining a urethane acrylate compound (A-1) (weight average molecular weight: 2,600, viscosity: 1,400 mPa·s/60°C, acid value: 5.2 mgKOH/g, acryloyl group concentration: 6.53 mmol/g).

[Preparation of urethane acrylate compound (A-2)]
Into a flask equipped with an internal thermometer, a stirrer, and a cooling tube, 137 g (0.617 mol) of isophorone diisocyanate, 4.57 g (0.031 mol) of dimethylolbutanoic acid, 12.4 g (0.093 mol) of dimethylolpropionic acid, and 0.1 g of dibutyltin dilaurate as a reaction catalyst were added and reacted at 90° C. When the residual isocyanate groups reached 26.9% or less, 666 g (0.617 mol) of an acrylic acid adduct of dipentaerythritol [hydroxyl value: 52.0 mgKOH/g] and 1.65 g of 2,6-di-t-butylcresol as a polymerization inhibitor were added and reacted at 70° C. When the residual isocyanate group became 1.9% or less, the mixture was cooled to 60°C, and 180 g (0.309 mol) of polyethylene glycol [hydroxyl value: 193.0 mgKOH/g, number average molecular weight calculated from the hydroxyl value: 581] was added and reacted at 60°C. When the residual isocyanate group became 0.1% or less, the reaction was terminated to obtain a urethane acrylate compound (A-2) (weight average molecular weight: 3,100, viscosity: 3,400 mPa·s/60°C, acid value: 6.9 mgKOH/g, acryloyl group concentration: 6.66 mmol/g).

[Preparation of urethane acrylate compound (A-3)]
Into a flask equipped with an internal thermometer, a stirrer, and a cooling tube, 137 g (0.617 mol) of isophorone diisocyanate, 666 g (0.617 mol) of an acrylic acid adduct of dipentaerythritol [hydroxyl value: 52.0 mgKOH/g], 1.65 g of 2,6-di-t-butylcresol as a polymerization inhibitor, and 0.1 g of dibutyltin dilaurate as a reaction catalyst were added and reacted at 70° C. When the residual isocyanate groups reached 3.2% or less, 4.57 g (0.031 mol) of dimethylolbutanoic acid and 12.4 g (0.093 mol) of dimethylolpropionic acid were added and reacted at 90° C. When the residual isocyanate group became 1.9% or less, the mixture was cooled to 60°C, and 180 g (0.309 mol) of polyethylene glycol [hydroxyl value: 193.0 mgKOH/g, number average molecular weight calculated from the hydroxyl value: 581] was added and reacted at 60°C. When the residual isocyanate group became 0.1% or less, the reaction was terminated to obtain a urethane acrylate compound (A-3) (weight average molecular weight: 2,700, viscosity: 3,000 mPa·s/60°C, acid value: 6.9 mgKOH/g, acryloyl group concentration: 6.66 mmol/g).

[Preparation of urethane acrylate compound (A-4)]
Into a flask equipped with an internal thermometer, a stirrer, and a cooling tube, 133 g (0.599 mol) of isophorone diisocyanate, 710 g (0.658 mol) of an acrylic acid adduct of dipentaerythritol [hydroxyl value: 52.0 mgKOH/g] (corresponding to (a3) of the present invention), 1.65 g of 2,6-di-t-butylcresol as a polymerization inhibitor, and 0.1 g of dibutyltin dilaurate as a reaction catalyst were added and reacted at 70° C. When the residual isocyanate groups reached 2.7% or less, 5.32 g (0.036 mol) of dimethylolbutanoic acid and 11.2 g (0.084 mol) of dimethylolpropionic acid were added and reacted at 90° C. When the residual isocyanate group became 1.5% or less, the mixture was cooled to 60°C, and 140 g (0.239 mol) of polyethylene glycol [hydroxyl value: 193.0 mgKOH/g, number average molecular weight calculated from the hydroxyl value: 581] was added and reacted at 60°C. When the residual isocyanate group became 0.1% or less, the reaction was terminated to obtain a urethane acrylate compound (A-4) (weight average molecular weight: 2,500, viscosity: 3,400 mPa·s/60°C, acid value: 6.7 mgKOH/g, acryloyl group concentration: 7.10 mmol/g).

[Preparation of urethane acrylate compound (A-5)]
Into a flask equipped with an internal thermometer, a stirrer, and a cooling tube, 135 g (0.608 mol) of isophorone diisocyanate, 754 g (0.699 mol) of an acrylic acid adduct of dipentaerythritol [hydroxyl value: 52.0 mgKOH/g], 1.65 g of 2,6-di-t-butylcresol as a polymerization inhibitor, and 0.1 g of dibutyltin dilaurate as a reaction catalyst were added and reacted at 70° C. When the residual isocyanate groups reached 2.4% or less, 4.95 g (0.033 mol) of dimethylolbutanoic acid and 11.0 g (0.082 mol) of dimethylolpropionic acid were added and reacted at 90° C. When the residual isocyanate group became 1.3% or less, the mixture was cooled to 60°C, and 94.7 g (0.239 mol) of polyethylene glycol [hydroxyl value: 288.0 mgKOH/g, number average molecular weight calculated from the hydroxyl value: 390] was added and reacted at 60°C. When the residual isocyanate group became 0.1% or less, the reaction was terminated to obtain a urethane acrylate compound (A-5) (weight average molecular weight: 2,500, viscosity: 5,300 mPa·s/60°C, acid value: 6.5 mgKOH/g, acryloyl group concentration: 7.54 mmol/g).

[Preparation of urethane acrylate compound (A-6)]
Into a flask equipped with an internal thermometer, a stirrer, and a cooling tube, 141 g (0.635 mol) of isophorone diisocyanate, 686 g (0.635 mol) of an acrylic acid adduct of dipentaerythritol [hydroxyl value: 52.0 mgKOH/g], 1.65 g of 2,6-di-t-butylcresol as a polymerization inhibitor, and 0.1 g of dibutyltin dilaurate as a reaction catalyst were added and reacted at 70° C. When the residual isocyanate groups reached 3.2% or less, 12.2 g (0.083 mol) of dimethylolbutanoic acid and 12.4 g (0.092 mol) of dimethylolpropionic acid were added and reacted at 90° C. When the residual isocyanate group became 1.4% or less, the mixture was cooled to 60°C, and 149 g (0.254 mol) of polyethylene glycol [hydroxyl value: 192.0 mgKOH/g, number average molecular weight calculated from the hydroxyl value: 584] was added and reacted at 60°C. When the residual isocyanate group became 0.1% or less, the reaction was terminated to obtain a urethane acrylate compound (A-6) (weight average molecular weight: 2,800, viscosity: 4,500 mPa·s/60°C, acid value: 9.8 mgKOH/g, acryloyl group concentration: 6.86 mmol/g).

[Preparation of urethane acrylate compound (A-7)]
Into a flask equipped with an internal thermometer, a stirrer, and a condenser, 141 g (0.635 mol) of isophorone diisocyanate, 343 g (0.318 mol) of an acrylic acid adduct of dipentaerythritol [hydroxyl value: 52.0 mgKOH/g], 1.65 g of 2,6-di-t-butylcresol as a polymerization inhibitor, and 0.1 g of dibutyltin dilaurate as a reaction catalyst were added and reacted at 70° C. When the residual isocyanate groups reached 8.2% or less, 12.2 g (0.083 mol) of dimethylolbutanoic acid and 12.4 g (0.092 mol) of dimethylolpropionic acid were added and reacted at 90° C. When the residual isocyanate group was 5.0% or less, the mixture was cooled to 70° C., and 343 g (0.318 mol) of an acrylic acid adduct of dipentaerythritol [hydroxyl value: 52.0 mg KOH/g] was added and reacted at 70° C. When the residual isocyanate group was 1.4% or less, the mixture was cooled to 60° C., and 149 g (0.254 mol) of polyethylene glycol [hydroxyl value: 192.0 mg KOH/g, number average molecular weight calculated from the hydroxyl value: 584] was added and reacted at 60° C. The reaction was terminated when the residual isocyanate group was 0.1% or less, to obtain a urethane acrylate compound (A-7) (weight average molecular weight: 2,800, viscosity: 4,800 mPa·s/60° C., acid value: 9.8 mg KOH/g, acryloyl group concentration: 6.86 mmol/g).

[Preparation of urethane acrylate compound (A-8)]
Into a flask equipped with an internal thermometer, a stirrer, and a cooling tube, 136 g (0.613 mol) of isophorone diisocyanate, 661 g (0.613 mol) of an acrylic acid adduct of dipentaerythritol [hydroxyl value: 52.0 mgKOH/g], 1.65 g of 2,6-di-t-butylcresol as a polymerization inhibitor, and 0.1 g of dibutyltin dilaurate as a reaction catalyst were added and reacted at 70° C. When the residual isocyanate groups reached 3.2% or less, 11.8 g (0.080 mol) of dimethylolbutanoic acid and 11.9 g (0.089 mol) of dimethylolpropionic acid were added and reacted at 90° C. When the residual isocyanate group became 1.4% or less, the mixture was cooled to 60°C, and 179 g (0.306 mol) of polyethylene glycol [hydroxyl value: 192.0 mgKOH/g, number average molecular weight calculated from the hydroxyl value: 584] was added and reacted at 60°C. When the residual isocyanate group became 0.1% or less, the reaction was terminated to obtain a urethane acrylate compound (A-8) (weight average molecular weight: 2,600, viscosity: 3,200 mPa·s/60°C, acid value: 9.5 mgKOH/g, acryloyl group concentration: 6.61 mmol/g).

[Preparation of urethane acrylate compound (A-9)]
Into a flask equipped with an internal thermometer, a stirrer, and a cooling tube, 130 g (0.586 mol) of isophorone diisocyanate, 728 g (0.674 mol) of an acrylic acid adduct of dipentaerythritol [hydroxyl value: 52.0 mgKOH/g], 1.65 g of 2,6-di-t-butylcresol as a polymerization inhibitor, and 0.1 g of dibutyltin dilaurate as a reaction catalyst were added and reacted at 70° C. When the residual isocyanate groups reached 2.4% or less, 11.8 g (0.080 mol) of dimethylolbutanoic acid and 11.8 g (0.088 mol) of dimethylolpropionic acid were added and reacted at 90° C. When the residual isocyanate group became 0.8% or less, the mixture was cooled to 60°C, and 118 g (0.202 mol) of polyethylene glycol [hydroxyl value: 192.0 mgKOH/g, number average molecular weight calculated from the hydroxyl value: 584] was added and reacted at 60°C. When the residual isocyanate group became 0.1% or less, the reaction was terminated to obtain a urethane acrylate compound (A-9) (weight average molecular weight: 2,600, viscosity: 5,000 mPa·s/60°C, acid value: 9.4, acryloyl group concentration: 7.28 mmol/g).

[Preparation of urethane acrylate compound (A-10)]
Into a flask equipped with an internal thermometer, a stirrer, and a condenser, 141 g (0.636 mol) of isophorone diisocyanate, 686 g (0.636 mol) of an acrylic acid adduct of dipentaerythritol [hydroxyl value: 52.0 mgKOH/g], 1.65 g of 2,6-di-t-butylcresol as a polymerization inhibitor, and 0.1 g of dibutyltin dilaurate as a reaction catalyst were added and reacted at 70° C. When the residual isocyanate groups reached 3.2% or less, 23.9 g (0.178 mol) of dimethylolpropionic acid was added and reacted at 90° C. When the residual isocyanate group became 1.4% or less, the mixture was cooled to 60°C, and 149 g (0.254 mol) of polyethylene glycol [hydroxyl value: 192.0 mgKOH/g, number average molecular weight calculated from the hydroxyl value: 584] was added and reacted at 60°C. When the residual isocyanate group became 0.1% or less, the reaction was terminated to obtain a urethane acrylate compound (A-10) (weight average molecular weight: 2,500, viscosity: 4,900 mPa·s/60°C, acid value: 10.0 mgKOH/g, acryloyl group concentration: 6.86 mmol/g).

[Preparation of urethane acrylate compound (A-11)]
Into a flask equipped with an internal thermometer, a stirrer, and a cooling tube, 141 g (0.634 mol) of isophorone diisocyanate, 684 g (0.634 mol) of an acrylic acid adduct of dipentaerythritol [hydroxyl value: 52.0 mgKOH/g], 1.65 g of 2,6-di-t-butylcresol as a polymerization inhibitor, and 0.1 g of dibutyltin dilaurate as a reaction catalyst were added and reacted at 70° C. When the residual isocyanate groups reached 3.2% or less, 26.3 g (0.178 mol) of dimethylolbutanoic acid was added and reacted at 90° C. When the residual isocyanate group became 1.4% or less, the mixture was cooled to 60°C, and 148 g (0.254 mol) of polyethylene glycol [hydroxyl value: 192.0 mgKOH/g, number average molecular weight calculated from the hydroxyl value: 584] was added and reacted at 60°C. When the residual isocyanate group became 0.1% or less, the reaction was terminated to obtain a urethane acrylate compound (A-11) (weight average molecular weight: 2,500, resin viscosity: 5,400 mPa·s/60°C, acid value: 10.0 mgKOH/g, acryloyl group concentration: 6.84 mmol/g).

[Preparation of urethane acrylate compound (A'-1)]
Into a flask equipped with an internal thermometer, a stirrer, and a condenser, 96.1 g (0.432 mol) of isophorone diisocyanate, 606 g (0.519 mol) of an acrylic acid adduct of dipentaerythritol [hydroxyl value: 48.0 mg KOH/g], 1.65 g of 2,6-di-t-butylcresol as a polymerization inhibitor, and 0.1 g of dibutyltin dilaurate as a reaction catalyst were placed, and the mixture was reacted at 70° C. When the residual isocyanate groups reached 2.1% or less, the mixture was cooled to 60°C, and 298 g (0.302 mol) of polyethylene glycol (hydroxyl value: 114.0 mgKOH/g, number average molecular weight calculated from the hydroxyl value: 984) was added and reacted at 60°C. The reaction was terminated when the residual isocyanate groups reached 0.1% or less, thereby obtaining a urethane acrylate compound (A'-1) (weight average molecular weight: 3,500, viscosity: 1,200 mPa·s/60°C, acid value: 0 mgKOH/g, acryloyl group concentration: 6.08 mmol/g).

[Preparation of urethane acrylate compound (A'-2)]
Into a flask equipped with an internal thermometer, a stirrer, and a condenser, 125 g (0.562 mol) of isophorone diisocyanate, 728 g (0.675 mol) of an acrylic acid adduct of dipentaerythritol [hydroxyl value: 52.0 mg KOH/g], 1.65 g of 2,6-di-t-butylcresol as a polymerization inhibitor, and 0.1 g of dibutyltin dilaurate as a reaction catalyst were placed and reacted at 70° C. When the residual isocyanate groups reached 2.2% or less, the mixture was cooled to 60°C, and 147 g (0.253 mol) of polyethylene glycol (hydroxyl value: 193.0 mgKOH/g, number average molecular weight calculated from the hydroxyl value: 581) was added and reacted at 60°C. The reaction was terminated when the residual isocyanate groups reached 0.1% or less, thereby obtaining a urethane acrylate compound (A'-2) (weight average molecular weight: 3,800, viscosity: 4,500 mPa·s/60°C, acid value: 0 mgKOH/g, acryloyl group concentration: 7.28 mmol/g).

[Preparation of urethane acrylate compound (A'-3)]
Into a flask equipped with an internal thermometer, a stirrer, and a cooling tube, 157 g (0.707 mol) of isophorone diisocyanate, 763 g (0.707 mol) of an acrylic acid adduct of dipentaerythritol [hydroxyl value: 52.0 mgKOH/g], 1.65 g of 2,6-di-t-butylcresol as a polymerization inhibitor, and 0.1 g of dibutyltin dilaurate as a reaction catalyst were added and reacted at 70° C. When the residual isocyanate groups reached 3.2% or less, 41.9 g (0.283 mol) of dimethylolbutanoic acid and 37.9 g (0.283 mol) of dimethylolpropionic acid were added and reacted at 90° C. The reaction was terminated when the residual isocyanate groups reached 0.1% or less, yielding a urethane acrylate compound (A'-3) (weight average molecular weight: 2,200, viscosity: 67,000 mPa·s/60° C., acid value: 31.7 mgKOH/g, acryloyl group concentration: 7.63 mmol/g).

The compositions of the urethane acrylate compounds obtained above are shown in Tables 1 and 2 below.

The urethane acrylate compound obtained above was dispersed in an aqueous solvent as described below to emulsify the compound, thereby preparing an active energy ray-curable emulsion composition.

Example 1
In a flask equipped with an internal thermometer, a stirrer, and a cooling tube, 300 g of the urethane acrylate compound (A-1) prepared in Production Example 1 was added, pre-stirred at 50°C, and 2.4 g of 25% aqueous ammonia solution (1.25 molar equivalents of ammonia per molar equivalent of acid) was added for neutralization. Thereafter, 697.6 g of ion-exchanged water at room temperature was added in five portions at intervals of 20 minutes or more, during which stirring was continued at 50°C. After stopping the heating, stirring was continued for another hour to obtain an active energy ray-curable emulsion composition (viscosity: 22 mPa·s/20°C, pH: 9.1) with a resin content of 30% of the urethane acrylate compound (A-1).

[Examples 2 to 11]
Except for using the urethane acrylate compound (A-2) to (A-11) instead of the urethane acrylate compound (A-1), the same procedure as in Example 1 was repeated to obtain active energy ray-curable emulsion compositions each having a resin content of 30% of the urethane acrylate compounds (A-2) to (A-11).

Comparative Example 1
An active energy ray-curable emulsion composition having a resin content of 30% of the urethane acrylate compound (A'-1) was obtained in the same manner as in Example 1, except that the urethane acrylate compound (A-1) was replaced with the urethane acrylate compound (A'-1) and neutralization was not performed.

Comparative Example 2
An attempt was made to obtain an active energy ray-curable emulsion composition in the same manner as in Comparative Example 1, except that the urethane acrylate compound (A'-2) was used instead of the urethane acrylate compound (A'-1). However, the composition could not be dispersed in water.

Comparative Example 3
An attempt was made to obtain an active energy ray-curable emulsion composition in the same manner as in Example 1, except that the urethane acrylate compound (A'-3) was used instead of the urethane acrylate compound (A-1). However, the composition could not be dispersed in water.

[Appearance of active energy ray-curable emulsion composition]
The appearance of the active energy ray-curable emulsion compositions with a resin content of 30% prepared in Examples 1 to 11 and Comparative Examples 1 to 3 was visually evaluated as follows. The results are shown in Tables 3 and 4 below.
(Evaluation Criteria)
○: Uniform dispersion without precipitation ×: Precipitation

[Stability of active energy ray-curable emulsion composition]
The active energy ray-curable emulsion compositions having a resin content of 30% obtained in Examples 1 to 11 and Comparative Example 1 were left to stand at 23° C. for two weeks, and then the appearance was visually evaluated as follows. The results are shown in Tables 3 and 4 below.
(Evaluation Criteria)
○: Uniform dispersion without precipitation ×: Precipitation

<<Preparation of coating sample for evaluation>>
1.2 parts of a eutectic mixture of 1-hydroxycyclohexyl phenyl ketone and benzophenone (manufactured by IGM Resins, "OMNILAD 500") as a photopolymerization initiator was blended and mixed with 100 parts of the active energy ray curable emulsion composition (resin content 30%) obtained in Examples 1 to 11 and Comparative Example 1. This was applied to an easily adhesive polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd.; Cosmoshine A4300, thickness 125 μm) using a bar coater and dried at 90°C for 3 minutes, and then irradiated with ultraviolet light from a high-pressure mercury lamp to an integrated light amount of 450 mJ/ ^cm2 to cure the active energy ray curable emulsion composition, thereby preparing a coating film sample for evaluation with a film thickness of 10 μm.
The obtained coating film samples for evaluation were used to carry out the following evaluations.
The evaluation results of Examples 1 to 11 and Comparative Example 1 are shown in Tables 3 and 4 below.

[Pencil hardness]
The pencil hardness of the above coating samples for evaluation was measured in accordance with JIS K 5600-5-4 and evaluated as follows.
The evaluation results of Examples 1 to 11 and Comparative Example 1 are shown in Tables 3 and 4 below.
(Evaluation Criteria)
◎・・・3H or more ○・・・2H
×...H or less

[Scratch resistance]
Using the above coating sample for evaluation, the coating surface was rubbed 10 times back and forth with a brass brush under a load of 1 kg, and the presence or absence of scratches was visually confirmed and evaluated as follows.
The evaluation results of Examples 1 to 11 and Comparative Example 1 are shown in Tables 3 and 4 below.
(Evaluation Criteria)
○: No scratches △: Some scratches ×: Many scratches

As is clear from Tables 3 and 4 above, the active energy ray-curable emulsion compositions of Examples 1 to 11, which contained the neutralized product of the urethane acrylate compound (A) obtained by reacting the components (a1) to (a4), were excellent in appearance and stability of the aqueous dispersion, and further, the cured coating film was excellent in pencil hardness and scratch resistance.
On the other hand, the active energy ray-curable emulsion composition of Comparative Example 1, which did not use the component (a1) and contained the urethane acrylate compound (A'-1) obtained by reacting the components (a2) to (a4), showed excellent appearance and stability of the aqueous dispersion and excellent scratch resistance of the cured coating film, but showed poor pencil hardness of the cured coating film.
Similarly, in Comparative Example 2, which did not use the component (a1) but contained a urethane acrylate compound (A'-2) obtained by reacting the components (a2) to (a4), the composition could not be dispersed in water, and no cured coating film was obtained.
Furthermore, the active energy ray-curable emulsion composition of Comparative Example 3, which did not use the component (a4) and contained the urethane acrylate compound (A'-3) obtained by reacting the components (a1) to (a3), could not be dispersed in water, and no cured coating film was obtained.

The active energy ray-curable resin composition of the present invention contains the above-mentioned urethane (meth)acrylate compound (A), and therefore is a self-emulsifying resin with excellent water dispersibility and excellent surface hardness and scratch resistance of the coating film. It is therefore extremely useful as a material for forming various coating films, such as paints, protective coating agents, anchor coating agents, coating agents for hard coats, inks, magnetic powder coating binders, coatings for sandblasting, pressure sensitive adhesives, adhesives, tackifiers, printing plates, etc.

Claims (10)

An active energy ray-curable resin composition comprising a self-emulsifiable urethane (meth)acrylate compound (A) obtained by reacting a carboxyl group-containing polyol (a1), a polyisocyanate compound (a2), a hydroxyl group-containing (meth)acrylate compound (a3), and an alkylene glycol derivative (a4) represented by the following general formula (1):
The self-emulsifiable urethane (meth)acrylate compound (A) is obtained by a method in which a polyisocyanate compound (a2), a hydroxyl group-containing (meth)acrylate compound (a3), a carboxyl group-containing polyol (a1), and an alkylene glycol derivative (a4) are sequentially charged and reacted, or by a method in which a polyisocyanate compound (a2), a carboxyl group-containing polyol (a1), a hydroxyl group-containing (meth)acrylate compound (a3), and an alkylene glycol derivative (a4) are sequentially charged and reacted,
the carboxyl group-containing polyol (a1) is an aliphatic polyhydroxycarboxylic acid, the hydroxyl group-containing (meth)acrylate compound (a3) is a compound having two or more (meth)acryloyl groups in one molecule, the proportion of the carboxyl group-containing polyol (a1) is 0.1 to 20% by weight based on the total of the carboxyl group-containing polyol (a1), the polyisocyanate compound (a2), the hydroxyl group-containing (meth)acrylate compound (a3) and the alkylene glycol derivative (a4) represented by general formula (1), an active energy ray-curable resin composition, characterized in that the proportion of the isocyanate compound (a2) is 1 to 80% by weight, the proportion of the hydroxyl group-containing (meth)acrylate compound (a3) is 10 to 95% by weight, the proportion of the alkylene glycol derivative (a4) represented by the following general formula (1) is 1 to 80% by weight, the (meth)acryloyl group concentration of the urethane (meth)acrylate compound (A) is 1 to 10 mmol/g, the acid value is 1 to 20 mgKOH/g, and the number average molecular weight of the alkylene glycol derivative (a4) is 100 to 20,000.

The active energy ray-curable resin composition according to claim 1, characterized in that the polyol (a1) containing a carboxy group is a diol monocarboxylic acid having a molecular weight of 100 to 200 or a neutralized salt thereof. The active energy ray-curable resin composition according to claim 1 or 2, characterized in that the urethane (meth)acrylate compound (A) is neutralized. The active energy ray curable resin composition according to any one of claims 1 to 3, characterized in that the polyisocyanate compound (a2) is an alicyclic polyisocyanate. The active energy ray-curable resin composition according to any one of claims 1 to 4, further comprising a photopolymerization initiator (B). The active energy ray-curable resin composition according to any one of claims 1 to 5, further comprising an ethylenically unsaturated monomer (C). The active energy ray-curable resin composition according to any one of claims 1 to 6, characterized in that it has self-emulsifying properties. An active energy ray curable emulsion composition, comprising the active energy ray curable resin composition according to any one of claims 1 to 7 dispersed in an aqueous solvent. A coating composition comprising the active energy ray-curable emulsion composition according to claim 8. A self-emulsifiable urethane (meth)acrylate compound obtained by reacting a carboxyl group-containing polyol (a1), a polyisocyanate compound (a2), a hydroxyl group-containing (meth)acrylate compound (a3), and an alkylene glycol derivative (a4) represented by the following general formula (1):
The self-emulsifiable urethane (meth)acrylate compound is obtained by a method in which a polyisocyanate compound (a2), a hydroxyl group-containing (meth)acrylate compound (a3), a carboxyl group-containing polyol (a1), and an alkylene glycol derivative (a4) are sequentially charged and reacted, or by a method in which a polyisocyanate compound (a2), a carboxyl group-containing polyol (a1), a hydroxyl group-containing (meth)acrylate compound (a3), and an alkylene glycol derivative (a4) are sequentially charged and reacted,
the carboxyl group-containing polyol (a1) is an aliphatic polyhydroxycarboxylic acid, the hydroxyl group-containing (meth)acrylate compound (a3) is a compound having two or more (meth)acryloyl groups in one molecule, and the ratio of the carboxyl group-containing polyol (a1) to the total of the carboxyl group-containing polyol (a1), the polyisocyanate compound (a2), the hydroxyl group-containing (meth)acrylate compound (a3) and the alkylene glycol derivative (a4) represented by the general formula (1) is 0.1 to 20 % by weight, the proportion of the polyisocyanate compound (a2) is 1 to 80% by weight, the proportion of the hydroxyl group-containing (meth)acrylate compound (a3) is 10 to 95% by weight, the proportion of the alkylene glycol derivative (a4) represented by the following general formula (1) is 1 to 80% by weight, the (meth)acryloyl group concentration is 1 to 10 mmol/g, the acid value is 1 to 20 mgKOH/g, and the number average molecular weight of the alkylene glycol derivative (a4) is 100 to 20,000.