JP7615658B2 - Composition, cured product, container, image forming apparatus, and image forming method - Google Patents

Description

The present invention relates to a composition, a cured product, a container, an image forming device, and an image forming method.

Inks containing active energy ray-curable compositions are known as inks used in inkjet recording methods. Among these, active energy ray-curable radical polymerizable inks are widely used from the viewpoints of ink production costs and storage stability.

From the viewpoint of scratch resistance, the active energy ray curable composition is required to have a high hardness of the cured product obtained by curing the composition. In addition, in recent years, from the viewpoint of environmental protection, the light source used for curing is being replaced from mercury lamps and metal halide lamps to light emitting diodes (LEDs). Therefore, an active energy ray curable composition having excellent curability that can be sufficiently cured even when the irradiation energy is small like the LED (for example, the accumulated light amount is 0.5 J/ ^cm2 or less) is required. In addition, as an industrial application, the use of printing using active energy ray curable inks on substrates to be processed is increasing. Therefore, the cured product is required to have adhesion to the substrate and flexibility (stretchability). Furthermore, the composition is widely used in an embodiment in which it is discharged by an inkjet recording method and applied to a substrate, etc., and from the viewpoint of discharge stability, it is necessary to have a low viscosity.

In recent years, active energy ray curable compositions containing active energy ray curable polyfunctional monomers have been proposed in order to improve the curability and hardness of the cured product (see Patent Documents 1-3). Also, active energy ray curable inkjet inks for decorative films containing cyclic polymerizable monomers have been proposed in order to improve the adhesion of the cured product to resin substrates (see Patent Document 4). Furthermore, photocurable compositions containing cyclic ether-based (meth)acrylate monomers and polyfunctional (meth)acrylate monomers as photopolymerizable monomers, and further containing urethane acrylate oligomers, etc., have been proposed in order to improve not only the adhesion to substrates but also the flexibility of the cured product and the viscosity of the composition (see Patent Documents 4-6).

The present invention aims to provide a low-viscosity composition that can produce a cured product that has hardness, curability, adhesion to various substrates, and extensibility.

（前記一般式（１）におけるＲは、炭素数１～６のアルキル基を表す。） The composition of the present invention as a means for solving the above problems comprises:
An acrylamide compound,
an acrylamide compound (A) having a glass transition temperature (Tg) of 50° C. or higher after curing;
A polymerizable compound (B) represented by general formula (1),
A monofunctional polymerizable compound having a heterocycle,
A monofunctional polymerizable compound (C) having a Tg of 30° C. or less after curing;
and (D) at least one of a urethane acrylate oligomer and an acrylate oligomer having a dendrimer structure,
The content of the oligomer (D) in the composition is 5.0 mass % or less.

(In the general formula (1), R represents an alkyl group having 1 to 6 carbon atoms.)

The present invention provides a low-viscosity composition that can produce a cured product that combines hardness, curability, adhesion to various substrates, and extensibility.

FIG. 1 is a schematic diagram showing an example of an image forming apparatus equipped with an ink-jet ejection means. FIG. 2 is a schematic diagram showing an example of another image forming apparatus (a three-dimensional image forming apparatus). FIG. 3A is a schematic explanatory diagram showing an example of a method for performing three-dimensional modeling using an active energy ray-curable composition. FIG. 3B is a schematic explanatory diagram showing an example of a method for performing three-dimensional modeling using an active energy ray-curable composition. FIG. 3C is a schematic explanatory diagram showing an example of a method for performing three-dimensional modeling using an active energy ray-curable composition. FIG. 3D is a schematic explanatory diagram showing an example of a method for performing three-dimensional modeling using an active energy ray-curable composition.

[Composition]
The active energy ray-curable composition of the present invention contains an acrylamide compound (A), which is an acrylamide compound having a glass transition temperature (Tg) of 50° C. or higher when cured, a polymerizable compound (B) represented by general formula (1), a monofunctional polymerizable compound (C) having a heterocycle, which is a monofunctional polymerizable compound having a Tg of 30° C. or lower when cured, and at least one of a urethane acrylate oligomer and an acrylate oligomer having a dendrimer structure (D), wherein the content of the oligomer (D) in the composition is 5.0 mass % or less, and further contains a colorant, an organic solvent, and other components as necessary.
The active energy ray-curable composition may be referred to as the "composition" hereinafter.
An acrylamide compound (A) having a glass transition temperature (Tg) of 50° C. or higher when cured may be hereinafter referred to as "acrylamide compound (A)."
The polymerizable compound (B) represented by general formula (1) may be referred to as "polymerizable compound (B)" hereinafter.
A monofunctional polymerizable compound (C) having a heterocycle, in which a Tg of a cured product of the monofunctional polymerizable compound is 30° C. or lower, may be referred to as “monofunctional polymerizable compound (C)” hereinafter.
At least one of the urethane acrylate oligomer and the acrylate oligomer having a dendrimer structure (D) may be referred to as "oligomer (D)" hereinafter.

Conventional active energy ray curable compositions contain polyfunctional monomers in order to impart excellent curability and high hardness to the cured products (coating films and laminates thereof) obtained from the compositions. However, most of the polyfunctional monomers have high viscosity, and therefore have problems in terms of ejection stability when used in inkjet recording methods.
In addition, the three-dimensional crosslinked structure formed by the polyfunctional monomer increases internal stress during curing, and the cured product shrinks in volume, causing clutches and distortion inside the cured product, which reduces adhesion to the substrate. It is known that the curability and high hardness, and the adhesion to the substrate are in a trade-off relationship, since they are each caused by the content of the polyfunctional monomer.
Furthermore, the cured product obtained by curing the active energy ray-curable composition containing the polyfunctional monomer does not have sufficient stretchability, and there are problems such as the generation of clutches and peeling when processing and molding a substrate or the like on which the cured product is formed.

As a result of extensive investigations, the inventors have found that the composition of the present invention contains three types of monofunctional monomers and at least one of a urethane acrylate oligomer and an acrylate oligomer having a dendrimer structure, and that the content of the oligomer (D) in the composition is 5.0 mass % or less, thereby making it possible to obtain a composition with low viscosity, and further, that the cured product obtained by curing the composition has excellent curability, high hardness, adhesion to multiple substrates, and high extensibility.

Therefore, in the present invention, the composition contains an acrylamide compound (A) having a glass transition temperature (Tg) of 50°C or higher, a polymerizable compound (B) represented by general formula (1), a monofunctional polymerizable compound (C) having a heterocycle, the monofunctional polymerizable compound having a Tg of 30°C or lower, and at least one of a urethane acrylate oligomer and an acrylate oligomer having a dendrimer structure (D), and the content of the oligomer (D) in the composition is 5.0% by mass or less, thereby realizing a low-viscosity composition and a cured product having excellent curability, high hardness, adhesion to multiple substrates, and high extensibility.

The composition of the present invention is preferably a curable composition.
The curable composition may be a heat curable composition or an active energy ray curable composition, with the active energy ray curable composition being preferred.

<Acrylamide compound (A)>
In the present invention, when the acrylamide compound has a glass transition temperature (Tg) of 50° C. or higher, the hardness of the surface of the cured product can be improved while maintaining adhesion to the substrate.

The acrylamide compound (A) is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include (meth)acrylamide, N-methyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-propyl(meth)acrylamide, N-n-butyl(meth)acrylamide, N-t-butyl(meth)acrylamide, N-butoxymethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N-methylol(meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, (meth)acryloylmorpholine, N-(2-hydroxyethyl)acrylamide, N-(hydroxymethyl)acrylamide, N-(butoxymethyl)acrylamide, N-[3-(dimethylamino)propyl]acrylamide, N-(1,1-dimethyl-3-oxobutyl)acrylamide, 2-acrylamido-2-methylpropanesulfonic acid, and diacetone acrylamide. Among these, (meth)acryloylmorpholine is preferred because of its high reactivity to light.
These may be used alone or in combination of two or more.

前記一般式（２）におけるＲ^１は、炭素数１～６のアルキル基を表し、Ｘは炭素数１～６のアルキレン基を表し、Ｙは下記一般式（３）及び下記一般式（４）のいずれかを表す。

前記一般式（３）におけるＲ^２は、炭素数１～１０のアルキル基を表し、＊は前記Ｘとの結合部位を表す。

前記一般式（４）におけるＲ^３は、炭素数１～１０のアルキル基を表し、＊は前記Ｘとの結合部位を表す。
本段落におけるアルキル基は、炭素数１～４の直鎖又は分岐のアルキル基が好ましく、炭素数１又は２のアルキル基（即ち、メチル基又はエチル基）がより好ましい。 The acrylamide compound (A) may be an acrylamide compound having an ester represented by the following general formula (2).

In the general formula (2), R ¹ represents an alkyl group having 1 to 6 carbon atoms, X represents an alkylene group having 1 to 6 carbon atoms, and Y represents any one of the following general formulas (3) and (4).

In the general formula (3), R ² represents an alkyl group having 1 to 10 carbon atoms, and * represents the bonding site with X.

In the general formula (4), R ³ represents an alkyl group having 1 to 10 carbon atoms, and * represents the bonding site with X.
The alkyl group in this paragraph is preferably a straight or branched alkyl group having 1 to 4 carbon atoms, and more preferably an alkyl group having 1 or 2 carbon atoms (ie, a methyl group or an ethyl group).

Examples of the compound represented by the general formula (2) include N-acryloyl-N-alkyl amino acid alkyl esters (including N-acryloylproline alkyl esters), N-acryloylpiperidine carboxylic acid alkyl esters, etc.

The N-acryloyl-N-alkyl amino acid alkyl ester is not particularly limited and can be appropriately selected depending on the purpose. Examples of the N-acryloyl-N-alkyl amino acid alkyl ester include N-acryloyl-N-methylglycine methyl ester, N-acryloyl-N-methylglycine ethyl ester, N-acryloyl-N-methylglycine propyl ester, N-acryloyl-N-methylglycine butyl ester, N-acryloyl-N-ethylglycine methyl ester, N-acryloyl-N-ethylglycine ethyl ester, N-acryloyl-N-ethylglycine propyl ester, N-acryloyl-N-propylglycine methyl ester, N-acryloyl-N-propylglycine ethyl ester, N-acryloyl-N-butylglycine methyl ester, N-acryloyl- Examples of the acryloyl-N-methylalanine methyl ester include N-acryloyl-N-methylalanine ethyl ester, N-acryloyl-N-methylalanine propyl ester, N-acryloyl-N-ethylalanine methyl ester, N-acryloyl-N-ethylalanine ethyl ester, N-acryloyl-N-propylalanine methyl ester, N-acryloyl-N-methyl-β-alanine methyl ester, N-acryloyl-N-methyl-β-alanine ethyl ester, N-acryloyl-N-ethyl-β-alanine methyl ester, N-acryloyl-N-ethyl-β-alanine ethyl ester, N-acryloyl-N-methylvaline methyl ester, N-acryloylproline methyl ester, and N-acryloylproline ethyl ester.
These may be used alone or in combination of two or more.

The N-acryloylpiperidine carboxylate alkyl ester is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include methyl N-acryloylpiperidine-2-carboxylate, methyl N-acryloylpiperidine-3-carboxylate, and methyl N-acryloylpiperidine-4-carboxylate.
These may be used alone or in combination of two or more.

The content of the acrylamide compound (A) in the composition is preferably 1.0% by mass or more and 60.0% by mass or less, more preferably 5.0% by mass or more and 50.0% by mass or less, and even more preferably 20.0% by mass or more and 40.0% by mass or less, in terms of the balance between curability, surface hardness, and adhesion.

The acrylamide compound (A) is preferably a colorless, transparent or pale yellow transparent liquid with low viscosity (100 mPa·s or less) at room temperature (25°C) for application to inkjet recording methods. From the viewpoint of user safety, it is also preferable that the acrylamide compound (A) is not strongly acidic or alkaline and does not contain harmful formaldehyde as an impurity.

<Polymerizable compound (B) represented by general formula (1)>
The polymerizable compound (B) is not particularly limited and may be appropriately selected depending on the purpose. In terms of high curability, the polymerizable compound (B) is preferably a compound in which R in general formula (1) is methyl or ethyl, and more preferably a compound in which R in general formula (1) is methyl.

Examples of the polymerizable compound (B) include methyl α-allyloxymethylacrylate, methyl α-hydroxymethylacrylate, etc. Among these, methyl α-allyloxymethylacrylate is preferred in terms of high adhesion to the substrate.
These may be used alone or in combination of two or more.

The content of the polymerizable compound (B) in the composition is preferably 5.0% by mass or more and 50.0% by mass or less, more preferably 7.0% by mass or more and 40.0% by mass or less, and even more preferably 10.0% by mass or more and 30.0% by mass or less, from the viewpoint of being able to achieve both adhesion to the substrate and hardness of the cured surface. When the content of the polymerizable compound (B) in the composition exceeds 5.0% by mass, sufficient adhesion to the substrate is obtained, and when it is less than 50.0% by mass, it is preferable because the cured coating film (cured product) is not dissolved during recoating.
In addition, the sum of the contents of the acrylamide compound (A) and the polymerizable compound (B) in the composition is preferably 20.0 mass% or more and 60.0 mass% or less, from the viewpoint of being able to achieve both adhesion to the substrate and hardness of the surface of the cured product.

<Monofunctional polymerizable compound (C)>
In the present invention, when the glass transition temperature (Tg) of the cured product of the monofunctional polymerizable compound having a heterocycle is 30° C. or lower, the adhesion to the substrate can be improved.

The monofunctional polymerizable compound (C) is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include tetrahydrofurfuryl acrylate, tetrahydrofurfuryl alcohol acrylic acid polymer ester, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate, cyclic trimethylolpropane formal acrylate, (3-ethyloxetan-3-yl)methyl acrylate, and γ-butyrolactone acrylate.
These may be used alone or in combination of two or more.

The content of the monofunctional polymerizable compound (C) in the composition is preferably 20.0% by mass or more and 60.0% by mass or less, more preferably 30.0% by mass or more and 60.0% by mass or less, and even more preferably 40.0% by mass or more and 50.0% by mass or less, in order to achieve both adhesion to the substrate and hardness of the cured product surface. If the content of the monofunctional polymerizable compound (C) in the composition exceeds 20.0% by mass, sufficient adhesion to the substrate and sufficient extensibility of the cured product can be obtained, and if it is less than 60.0% by mass, sufficient hardness of the cured product surface can be obtained.

<Oligomer (D)>
As the oligomer (D), at least one of a urethane acrylate oligomer and an acrylate oligomer having a dendrimer structure can be used.
In the present invention, the acrylate oligomer having a dendrimer structure does not include a urethane acrylate oligomer.

- Urethane acrylate oligomer -
Examples of the urethane acrylate oligomer include aromatic urethane acrylate oligomers and aliphatic urethane acrylate oligomers, which can provide high toughness (hardness) and flexibility.

-Dendrimer structure-
The dendrimer structure in the present invention means a multi-branched polymer having a branched structure in which branched molecular structures as basic units are repeatedly bonded to a polyfunctional compound that is the center of the molecular structure called a core molecule.

By using a polymerizable oligomer having a dendrimer structure, a three-dimensional crosslinked structure is formed due to the radial structure specific to the oligomer, and a cured product having a high crosslink density (hardness) can be obtained, thereby achieving high abrasion resistance.
Furthermore, the polymerizable oligomer having a dendrimer structure is a relatively large molecule, so that the cured product has a large curing unit, and a uniform cured product can be obtained. Furthermore, compared with a general linear oligomer, the polymerizable oligomer having a dendrimer structure can efficiently relieve external stress or internal stress due to its unique three-dimensional structure. Therefore, by using a polymerizable oligomer having a dendrimer structure that combines a large curing unit and stress relaxation properties, a cured product with improved tolerance to scratches and cracks due to non-uniformity inside the composition can be obtained.

In the present invention, by using an acrylate oligomer having a dendrimer structure, it is possible to suppress cure shrinkage and improve the hardness of the cured surface while maintaining high adhesion to the substrate.

As the oligomer (D), an oligomer having 2 to 5 unsaturated carbon-carbon bonds is preferred, and an oligomer having 2 unsaturated carbon-carbon bonds is more preferred, in terms of obtaining good curability.
In the present invention, the oligomer means a polymer having 2 or more and 20 or less repeating monomer structural units.

The oligomer (D) may be an appropriately synthesized product or a commercially available product.
Examples of the commercially available products include UV-2000B, UV-2750B, UV-3000B, UV-3010B, UV-3200B, UV-3300B, UV-3700B, UV-6640B, UV-8630B, UV-7000B, UV-7610B, UV-1700B, UV-7630B, UV-6300B, UV-6640B, UV-7550B, and UV-7600B. , UV-7605B, UV-7610B, UV-7630B, UV-7640B, UV-7650B (all manufactured by Mitsubishi Chemical Corporation), CN929, CN961E75, CN961H81, CN962, CN963, CN963A80, CN963B80, CN963E75, CN963E80, CN963J85, CN964, CN965, CN965A80, CN966A80, CN966H90, CN966J75, CN980, CN981, CN981A75, CN981B88, CN982, CN982A75, CN982B88, CN 982E75, CN983, CN985B88, CN996, CN9001, CN9002, CN9788, CN9893, CN968, CN902, CN902J75, CN940, CN944, CN944B85, CN959, CN966, CN966B85, CN969, CN970, CN971J75, CN972, CN973, CN977, CN984, CN 985, CN986, CN989, CN991, CN992, CN994, CN997, CN999, CN9004, CN9005, CN9006, CN9007, CN9008, CN9 009, CN9010, CN9011, CN9013, CN9018, CN9019, CN9024, CN9025, CN9026, CN9028, CN9029, CN9030, CN9060, CN9165, CN9167, CN9178, CN9290, CN9782, CN9783 (all manufactured by Sartomer Corporation), EBECRYL230, EBECRYL270, EBECRYL4666, KRM8200, EBECRYL5129, EBECRYL8210, EBECRYL8301, EBECRYL8804, EBECRYL8807, EBE CRYL9260, KRM7735, KRM8296, KRM8452, EBECRYL4858, EBECRYL8402, EBECRYL9270, EBECRYL8311, EBE Examples of the urethane acrylate oligomers include CRYL8701 (manufactured by Daicel-Cytec Co., Ltd.): aliphatic urethane acrylate oligomers, CN970A60, CN970E60, CN971, CN971A80, CN973A80, CN973H85, CN973J75, CN975, CN977C70, CN978 (manufactured by Sartomer Co., Ltd.), EBECRYL210, EBECRYL220 (manufactured by Daicel-Cytec Co., Ltd.): aromatic urethane acrylate oligomers, V#1000 (manufactured by Osaka Organic Chemical Industry Co., Ltd.), CN2302, CN2303, CN2304 (manufactured by Sartomer Co., Ltd.), 6361-100, 6363, DR-E522 (manufactured by Choko Materials Co., Ltd.): acrylate oligomers having a dendrimer structure.

The content of the oligomer (D) in the composition is preferably 5.0% by mass or less from the viewpoint of suppressing the viscosity of the composition without reducing the adhesion to the substrate.

The weight average molecular weight of the oligomer (D) is not particularly limited and may be appropriately selected depending on the purpose. It is preferably from 1,000 to 30,000, more preferably from 5,000 to 20,000, in terms of polystyrene.
The weight average molecular weight can be measured, for example, by gel permeation chromatography (GPC).

<Polymerizable compound (E) other than (A), (B), (C) and (D)>
To the composition of the present invention, if necessary, another polymerizable compound (E) (hereinafter, sometimes referred to as another polymerizable compound (E)) other than the acrylamide compound (A), the polymerizable compound (B), the monofunctional polymerizable compound (C), and the oligomer (D) may be added.
The other polymerizable compound (E) is not particularly limited as long as it can undergo a polymerization reaction by irradiation with active energy rays (ultraviolet rays, electron beams, etc.), and can be appropriately selected depending on the purpose. Examples of the other polymerizable compound (E) include a radical polymerizable compound and a polymerizable oligomer.
The other polymerizable compounds (E) may be used alone or in combination of two or more in order to adjust the reaction rate, the ink properties, and the cured film properties.

The radical polymerizable compound is not particularly limited and can be appropriately selected depending on the purpose. Examples of the radical polymerizable compound include (meth)acrylate compounds, (meth)acrylamide compounds, and aromatic vinyl compounds.
These may be used alone or in combination of two or more.
In this specification, (meth)acrylate means at least one of acrylate and methacrylate, and (meth)acrylic means at least one of acrylic and methacrylic.

-(Meth)acrylate compound-
The (meth)acrylate compound is not particularly limited and can be appropriately selected depending on the purpose. Examples of the (meth)acrylate compound include monofunctional (meth)acrylates, difunctional (meth)acrylates, trifunctional (meth)acrylates, tetrafunctional (meth)acrylates, pentafunctional (meth)acrylates, and hexafunctional (meth)acrylates.
These may be used alone or in combination of two or more.

Examples of the monofunctional (meth)acrylate include hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, tert-octyl (meth)acrylate, isoamyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, cyclohexyl (meth)acrylate, 4-n-butylcyclohexyl (meth)acrylate, bornyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, butoxyethyl (meth)acrylate, 2-chloroethyl (meth)acrylate, 4-bromobutyl (meth)acrylate, cyanoethyl (meth)acrylate, benzyl (meth)acrylate, butoxymethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, alkoxymethyl (meth)acrylate, alkoxy Ethyl (meth)acrylate, 2-(2-methoxyethoxy)ethyl (meth)acrylate, 2-(2-butoxyethoxy)ethyl (meth)acrylate, 2,2,2-tetrafluoroethyl (meth)acrylate, 1H,1H,2H,2H-perfluorodecyl (meth)acrylate, 4-butylphenyl (meth)acrylate, phenyl (meth)acrylate, 2,4,5-tetramethylphenyl (meth)acrylate, 4-chlorophenyl (meth)acrylate, phenoxymethyl (meth)acrylate, phenoxyethyl (meth)acrylate, glycidyl (meth)acrylate, glycidyloxybutyl (meth)acrylate, glycidyloxyethyl (meth)acrylate, glycidyloxypropyl (meth)acrylate, hydroxyalkyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl butyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, diethylaminopropyl (meth)acrylate, trimethoxysilylpropyl (meth)acrylate, trimethylsilylpropyl (meth)acrylate, polyethylene oxide monomethyl ether (meth)acrylate, oligoethylene oxide monomethyl ether (meth)acrylate, polyethylene oxide (meth)acrylate, oligoethylene oxide (meth)acrylate, oligoethylene oxide monoalkyl ether (meth)acrylate, polyethylene oxide monoalkyl ether (meth)acrylate, dipropylene glycol (meth)acrylate, polypropylene oxide monoalkyl ether (meth)acrylate ) acrylate, oligopropylene oxide monoalkyl ether (meth)acrylate, 2-methacryloyloxytyl succinic acid, 2-methacryloyloxyhexahydrophthalic acid, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, butoxydiethylene glycol (meth)acrylate, trifluoroethyl (meth)acrylate, perfluorooctylethyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, ethylene oxide modified phenol (meth)acrylate, ethylene oxide modified cresol (meth)acrylate, ethylene oxide modified nonylphenol (meth)acrylate, propylene oxide modified nonylphenol (meth)acrylate, ethylene oxide modified 2-ethylhexyl (meth)acrylate, 2-(2-vinyloxyethoxy)ethyl acrylate, benzyl acrylate, and the like.
Among these, from the viewpoints of low viscosity, low odor, and high curing property, phenoxyethyl (meth)acrylate, benzyl acrylate, 2-(2-vinyloxyethoxy)ethyl acrylate, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate are preferred, and from the viewpoints of compatibility with photopolymerization initiators and other monomers, phenoxyethyl (meth)acrylate, benzyl acrylate, and 2-(2-vinyloxyethoxy)ethyl acrylate are particularly preferred.
These may be used alone or in combination of two or more.

Examples of the bifunctional (meth)acrylate include 1,6-hexanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 2,4-dimethyl-1,5-pentanediol di(meth)acrylate, butylethylpropanediol (meth)acrylate, ethoxylated cyclohexanemethanol di(meth)acrylate, 2-ethyl-2-butyl-butanediol di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acrylate, bisphenol F polyethoxy di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 2-ethyl-2-butylpropanediol di(meth)acrylate, 1,9-nonanedi(meth)acrylate, propoxylated ethoxylated bisphenol A di(meth)acrylate, and tricyclodecane di(meth)acrylate.
These may be used alone or in combination of two or more.

Examples of the trifunctional (meth)acrylate include trimethylolpropane tri(meth)acrylate, trimethylolethane tri(meth)acrylate, alkylene oxide-modified tri(meth)acrylate of trimethylolpropane, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, trimethylolpropane tri((meth)acryloyloxypropyl)ether, alkylene oxide-modified tri(meth)acrylate of isocyanuric acid, dipentaerythritol propionate tri(meth)acrylate, tri((meth)acryloyloxyethyl)isocyanurate, hydroxypivalaldehyde-modified dimethylolpropane tri(meth)acrylate, sorbitol tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, and ethoxylated glycerin tri(meth)acrylate.
These may be used alone or in combination of two or more.

Examples of the tetrafunctional (meth)acrylate include sorbitol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, and dipentaerythritol propionate tetra(meth)acrylate.
These may be used alone or in combination of two or more.

An example of the pentafunctional (meth)acrylate is sorbitol penta(meth)acrylate.
These may be used alone or in combination of two or more.

Examples of the hexafunctional (meth)acrylate include dipentaerythritol hexa(meth)acrylate, sorbitol hexa(meth)acrylate, alkylene oxide-modified hexa(meth)acrylate of phosphazene, and caprolactone-modified dipentaerythritol hexa(meth)acrylate.
These may be used alone or in combination of two or more.

- Aromatic vinyl compounds -
Examples of the aromatic vinyl compound include styrene, methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, isopropylstyrene, chloromethylstyrene, methoxystyrene, acetoxystyrene, chlorostyrene, dichlorostyrene, bromostyrene, vinyl benzoic acid methyl ester, 3-methylstyrene, 4-methylstyrene, 3-ethylstyrene, 4-ethylstyrene, 3-propylstyrene, 4-propylstyrene, 3-butylstyrene, 4-butylstyrene, 3-hexylstyrene, 4-hexylstyrene, 3-octylstyrene, 4-octylstyrene, 3-(2-ethylhexyl)styrene, 4-(2-ethylhexyl)styrene, allylstyrene, isopropenylstyrene, butenylstyrene, octenylstyrene, 4-t-butoxycarbonylstyrene, 4-methoxystyrene, and 4-t-butoxystyrene.
These may be used alone or in combination of two or more.

-Polymerizable oligomer-
The polymerizable oligomer is not particularly limited and may be appropriately selected depending on the purpose, and examples thereof include epoxy acrylate oligomers, polyester acrylate oligomers, special oligomers other than dendrimer acrylates, etc. Among these, oligomers having 2 to 5 unsaturated carbon-carbon bonds are preferred, and oligomers having 2 unsaturated carbon-carbon bonds are more preferred, in terms of obtaining good curability.
These may be used alone or in combination of two or more.
In the present invention, the oligomer means a polymer having 2 or more and 20 or less repeating monomer structural units.

The weight average molecular weight of the polymerizable oligomer is not particularly limited and may be appropriately selected depending on the purpose. In terms of polystyrene, the weight average molecular weight is preferably from 1,000 to 30,000, and more preferably from 5,000 to 20,000.
The weight average molecular weight can be measured, for example, by gel permeation chromatography (GPC).

<Coloring material>
The composition of the present invention may contain a coloring material.
The coloring material is not particularly limited and can be appropriately selected depending on the purpose. Various pigments and dyes that impart glossy colors such as black, white, magenta, cyan, yellow, green, orange, gold, and silver can be used.
The composition of the present invention may be colorless and transparent without containing a coloring material, and is suitable, for example, as an overcoat layer for protecting an image.

The pigment is not particularly limited and can be appropriately selected depending on the purpose, and examples of the pigment include inorganic pigments and organic pigments.
These may be used alone or in combination of two or more.

Examples of the inorganic pigments include carbon blacks (C.I. Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black, iron oxide, and titanium oxide.

Examples of the organic pigments include azo pigments such as insoluble azo pigments, condensed azo pigments, azo lakes, and chelate azo pigments; polycyclic pigments such as phthalocyanine pigments, perylene and perinone pigments, anthraquinone pigments, quinacridone pigments, dioxane pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments; dye chelates (basic dye chelates, acid dye chelates, etc.); dye lakes (basic dye lakes, acid dye lakes), nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments.

In order to improve the dispersibility of the pigment, a dispersant may be further contained.
The dispersant is not particularly limited and can be appropriately selected depending on the purpose. Examples of the dispersant include dispersants commonly used for preparing pigment dispersions, such as polymer dispersants.

The dye is not particularly limited and can be appropriately selected depending on the purpose. Examples of the dye include acid dyes, direct dyes, reactive dyes, and basic dyes.
These may be used alone or in combination of two or more.

The content of the colorant in the composition may be appropriately selected taking into consideration the desired color density, dispersibility in the composition, etc., and is not particularly limited, but is preferably 0.1% by mass or more and 20% by mass or less.

<Organic solvent>
The composition of the present invention may contain an organic solvent, but preferably does not contain an organic solvent if possible.
If the composition does not contain the organic solvent, particularly a volatile organic solvent (VOC (Volatile Organic Compounds)-free), the safety of the place where the composition is handled can be further increased, and it is also possible to prevent environmental pollution.
In the present invention, the organic solvent refers to a general non-reactive organic solvent such as ether, ketone, xylene, ethyl acetate, cyclohexanone, toluene, etc., and should be distinguished from a reactive monomer.
In the present invention, "containing no organic solvent" means that the organic solvent is substantially not contained, and the content of the organic solvent is preferably less than 0.1% by mass based on the total amount of the composition.

<Other ingredients>
The other components are not particularly limited and can be appropriately selected depending on the purpose. Examples of the other components include a polymerization initiator, a hydrogen donor, a surfactant, a polymerization inhibitor, a leveling agent, an antifoaming agent, a fluorescent brightening agent, a penetration promoter, a wetting agent (moisturizing agent), a fixing agent, a viscosity stabilizer, an antifungal agent, a preservative, an antioxidant, an ultraviolet absorbing agent, a chelating agent, a pH adjuster, and a thickener.

--Polymerization initiator (F)--
The polymerization initiator (F) is not particularly limited as long as it is capable of generating active species such as radicals or cations by the energy of active energy rays and initiating polymerization of a polymerizable compound (monomer or oligomer), and can be appropriately selected depending on the purpose. For example, known radical polymerization initiators and cationic polymerization initiators can be mentioned, and it is preferable to use a radical polymerization initiator.
These may be used alone or in combination of two or more.

Examples of the radical polymerization initiator include aromatic ketones, acylphosphine oxide compounds, aromatic onium salt compounds, organic peroxides, thio compounds (thioxanthone compounds, thiophenyl group-containing compounds, etc.), hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having a carbon-halogen bond, and alkylamine compounds.

Specific examples of the radical polymerization initiator include benzophenone, acetophenone, 2-hydroxy-2-phenylacetophenone, 2-ethoxy-2-phenylacetophenone, 2-methoxy-2-phenylacetophenone, 2-isopropoxy-2-phenylacetophenone, 2-isobutoxy-2-phenylacetophenone, 4-methoxyacetophenone, 4-benzyloxyacetophenone, 4-phenylacetophenone, 4-benzoyl 4'-methyldiphenyl sulfide, methyl benzoylformate, ethyl benzoylformate, 2-hydroxy-1-(4-isopropenylphenyl)-2-methylpropan-1-one oligomer [benzene, (1-methylethynyl)-, homopolymer, ar-(2-hydroxy-2-methyl-1-oxopropyl) derivative] (manufactured by IGM, "Esacure"ONE"), 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1 (trade name "Irgacure 369"), bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (trade name "Irgacure 819"), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (trade name "Irgacure TPO"), polyethylene glycol 200-di(β-4(4-(2-dimethylamino-2-benzyl)butanonylphenyl)piperazine) (manufactured by IGM, "Omnipol"910"), 1,3-di({α-[1-chloro-9-oxo-9H-thioxanthen-4-yl)oxy]acetylpoly[oxy(1-methylethylene)]}oxy)-2,2-bis({α-[1-chloro-9-oxo-9H-thioxanthen-4-yl)oxy]acetylpoly[oxy(1-methylethylene)]}oxymethyl)propane (Lambson, "Speedcure 7010"), polybutylene glycol bis(9-oxo-9H-thioxanthenyloxy)acetate (IGM, "Omnipol TX"), and polymeric thioxanthene compound (Lahn AG, "Genepol TX-2").
These may be used alone or in combination of two or more.

The content of the polymerization initiator (F) in the composition is preferably 5.0% by mass or more and 20.0% by mass or less, from the viewpoint of obtaining a sufficient curing speed.

-Hydrogen donor (G)-
In the composition of the present invention, polymerization is initiated by the compound having a benzophenone skeleton or the like through the mechanism shown below.
When a compound having a benzophenone skeleton or the like is excited by light irradiation, the excited molecule extracts hydrogen from a nearby compound. A radical is generated in the compound from which hydrogen has been extracted, and the compound from which hydrogen has been extracted becomes the initiation point of radical polymerization. As a result, the compound having a benzophenone skeleton or the like acts as a photoradical polymerization initiator. That is, if a compound that can extract hydrogen is present together with a compound having a benzophenone skeleton or the like, polymerization is initiated by the above-mentioned polymerization initiation mechanism.
For example, if a hydrogen atom is abstracted from the radically polymerizable compound used in the present invention by a compound having a benzophenone skeleton or the like, polymerization may be initiated at that point.

The composition of the present invention can also contain a hydrogen donor (G) from which hydrogen is easily extracted. In this case, hydrogen is more smoothly transferred from the hydrogen donor compound to the compound molecule having a benzophenone skeleton or the like excited by light irradiation, and polymerization can proceed more efficiently. In other words, by adding the hydrogen donor to a polymerization initiator that does not absorb in the 365 to 405 nm range, it is possible to greatly improve the polymerization reactivity while maintaining low yellowing of the resin component.

The hydrogen donor (G) is not particularly limited as long as it is a compound that can smoothly donate hydrogen to a compound molecule having a benzophenone skeleton excited by light irradiation, and can be appropriately selected according to the purpose. For example, compounds having an amino group such as diethylamine, diphenylamine, triethylamine, tributylamine, diethanolamine, triethanolamine, N,N-diethylethanolamine, N,N-diethylmethylamine, dipropylamine, N,N-dimethylaniline, ethyl p-diethylaminobenzoate, and ethyl p-dimethylaminobenzoate; compounds having a hydroxyl group such as methanol, ethanol, propanol, isopropyl alcohol, butanol, ethylene glycol, propylene glycol, butanediol, and phenol; tetrahydrofuran, tetrahydropyran, dioxane, trioxane, and diethylene glycol; Compounds having an ether bond such as dipropylene glycol, propylene glycol monomethyl ether, and propylene glycol monomethyl ether acetate; mercapto compounds such as butanethiol, propanethiol, hexanedithiol, decanedithiol, n-dodecyl mercaptan, dodecyl (4-methylthio)phenyl ether, benzenethiol, 4-dimethylmercaptobenzene, 2-mercaptoethanol, 1-mercapto-2-propanol, 3-mercapto-2-butanol, 3-mercapto-1,2-propanediol, and mercaptophenol; or disulfides obtained by oxidizing these compounds; butyl thioglycolate, ethylene glycol bisthioglycolate, ethylene glycol bisthiopropionate, butanediol bis(3-mercaptoisobutyrate), 1,4-butanediol bisthioglycolate, 1,4- Butanediol bisthiopropionate, octyl β-mercaptopropionate, methoxybutyl β-mercaptopropionate, trishydroxyethyl tristhiopropionate, trimethylolpropane tris(3-mercaptoisobutyrate), trimethylolpropane tris(3-mercaptobutyrate), trimethylolpropane tris(3-mercaptopropionate), trimethylolpropane tris(β-thiopropionate), trimethylolpropane tristhioglycolate, trimethylolpropane tristhiopropionate, pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakisthioglycolate, pentaerythritol tetrakisthiopropionate, thioglycolic acid, thiosalicylic acid, thiomalic acid, mercaptoacetic acid, 2-mercaptoethanesulfonic acid, 2- Mercaptonicotinic acid, 2-mercaptopropionic acid, 3-mercaptopropanesulfonic acid, 3-mercaptopropionic acid, 3-mercaptobutyric acid, 4-mercaptobutanesulfonic acid, 3-[N-(2-mercaptoethyl)amino]propionic acid, 3-[N-(2-mercaptoethyl)carbamoyl]propionic acid, 2-mercapto-3-pyridinol, 2-mercaptoimidazole, 2-mercaptoethylamine, 2-mercapto-3-pyridinol, 2-mercaptoimidazole, 2-mercaptoethylamine, Examples of compounds having a mercapto group include mercaptobenzimidazole, 2-mercaptobenzothiazole, 6-trimercapto-s-triazine, N-(2-mercaptopropionyl)glycine, N-(3-mercaptopropionyl)alanine, diisopropylthioxanthone, diethylthioxanthone, thiophosphites, and trimercaptopropionic acid tris(2-hydroxyethyl)isocyanurate.

The hydrogen donor (G) may be a compound having an amino group, since the energy required for transferring hydrogen is small. For example, methyl 2-(N,N-dimethylamino)benzoate, ethyl 4-(N,N-dimethylamino)benzoate, ethyl 4-(N,N-diethylamino)benzoate, or a mixture of 1,3-di({α-4-(dimethylamino)benzoylpoly[oxy(1-methylethylene)]}oxy)-2,2-bis({α-4-(dimethylamino)benzoylpoly[oxy(1-methylethylene)]}oxymethyl)propane and {α-4-(dimethylamino)benzoylpoly(oxyethylene)-poly[oxy(1-methylethylene)]-poly(oxyethylene)}4-(dimethylamino)benzoate (manufactured by Lambson, "Speedcure 7040") is preferred.

The content of the hydrogen donor (G) is preferably 0.1% by mass or more and 50.0% by mass or less, more preferably 0.1% by mass or more and 20.0% by mass or less, based on the content of the radical polymerizable compound in the composition of the present invention.

--Surfactants--
The surfactant is not particularly limited and can be appropriately selected depending on the purpose. Examples of the surfactant include silicone-based surfactants and fluorine-based surfactants.
These may be used alone or in combination of two or more.

--Polymerization inhibitor--
The polymerization inhibitor is not particularly limited and can be appropriately selected depending on the purpose. Examples of the polymerization inhibitor include 4-methoxyphenol, dibutylhydroxytoluene, and phenothiazine.
These may be used alone or in combination of two or more.

The viscosity of the composition in the present invention may be appropriately adjusted depending on the application and means of application, and is not particularly limited. For example, when a discharge means is used in which the composition is discharged from a nozzle, the viscosity in the range of 20°C to 65°C, preferably the viscosity at 25°C, is 60 mPa·s or less, preferably 3 mPa·s or more and 40 mPa·s or less, more preferably 5 mPa·s or more and 30 mPa·s or less, even more preferably 5 mPa·s or more and 15 mPa·s or less, and particularly preferably 6 mPa·s or more and 12 mPa·s or less.
It is particularly preferred that the preferred viscosity ranges for the composition of the present invention are met without the inclusion of any of the organic solvents.
The viscosity can be measured by a cone-plate type rotational viscometer VISCOMETER TVE-22L manufactured by Toki Sangyo Co., Ltd., using a cone rotor (1°34′×R24), rotating at 50 rpm, and appropriately selecting the temperature of the constant temperature circulating water in the range of 20° C. to 65° C. A VISCOMATE VM-150III can be used to adjust the temperature of the circulating water.

<Preparation of Composition>
The composition of the present invention can be prepared using the various components described above. The preparation means and conditions are not particularly limited. For example, the composition can be prepared by putting a polymerizable monomer, a pigment, a dispersant, etc. into a dispersing machine such as a ball mill, a Kitty mill, a disk mill, a pin mill, or a Dyno mill, dispersing the ingredients to prepare a pigment dispersion, and further mixing a polymerizable monomer, a polymerization initiator, a polymerization inhibitor, a surfactant, etc. into the pigment dispersion.

<Uses of the composition>
The use of the composition of the present invention is not particularly limited as long as it is in a field in which active energy ray-curable materials are generally used, and can be appropriately selected depending on the purpose. Examples of the use include molding resins, paints, adhesives, insulating materials, release agents, coating materials, sealing materials, various resists, and various optical materials.
The composition of the present invention can be used as an active energy ray-curable ink to form two-dimensional characters, images, and decorative coating films on various substrates, and can also be used as a material for three-dimensional modeling to form three-dimensional images (three-dimensional objects).
The three-dimensional modeling material may be used, for example, as a binder between powder particles used in a powder lamination method in which a three-dimensional modeling is performed by repeatedly curing and laminating a powder layer, or may be used as a three-dimensional construction material (model material) or a support member (support material) in an additive manufacturing method (photo-modeling method) as shown in Figure 2 or Figure 3 (Figures 3A to 3D). Note that Figure 2 shows a method of discharging the composition of the present invention into a predetermined area, irradiating it with active energy rays, and sequentially laminating the cured products to perform three-dimensional modeling (described in detail later), and Figure 3 (Figures 3A to 3D) shows a method of irradiating a storage pool (container) 1 of the composition 5 of the present invention with active energy rays 4 to form a cured layer 6 of a predetermined shape on a movable stage 3, and sequentially laminating these to perform three-dimensional modeling.

[Image forming method and image forming apparatus]
The image forming method of the present invention has an irradiation step for irradiating with active energy rays, and, if necessary, has a discharge step for discharging the active energy ray-curable composition of the present invention.
The image forming apparatus of the present invention has an irradiation means for irradiating with active energy rays, and a storage section for storing the active energy ray-curable composition of the present invention.
The image forming apparatus may, if necessary, accommodate a container in the accommodation section, and may have a discharge means for discharging the composition of the present invention.

<Irradiation means and irradiation process>
The irradiation means is a means for irradiating the active energy ray-curable composition of the present invention with active energy rays.
The irradiation step is a step of irradiating the active energy ray-curable composition of the present invention with active energy rays.

- Active energy rays -
The curing means for curing the composition of the present invention includes heat curing and curing with active energy rays, and among these, curing with active energy rays is preferred.
The active energy rays may be any rays that can impart energy necessary to promote the polymerization reaction of the polymerizable components in the composition, and may be appropriately selected depending on the purpose. Examples of the active energy rays include ultraviolet rays, electron beams, α rays, β rays, γ rays, and X-rays.
The composition of the present invention can undergo a polymerization reaction without using a polymerization initiator by irradiating it with active energy rays using a high-energy light source.
When the active energy rays are ultraviolet rays, mercury-free devices are strongly desired from the viewpoint of environmental protection, and replacement with GaN-based semiconductor ultraviolet light-emitting devices is extremely useful from the industrial and environmental viewpoints. Furthermore, ultraviolet light-emitting diodes (UV-LEDs) and ultraviolet laser diodes (UV-LDs) are small, have a long life, are highly efficient, and are low cost, and are therefore preferred as ultraviolet light sources. Among these, ultraviolet light having a peak wavelength of 285 nm to 405 nm, preferably 365 to 405 nm, emitted from ultraviolet light-emitting diodes (hereinafter also referred to as UV-LEDs) is preferred from the viewpoint of energy saving and device miniaturization.
In addition, the light absorption spectrum of a polymerization initiator is generally broad, and the use of a UV-LED that irradiates a narrow specific wavelength range makes it difficult to improve the curability of the composition. Therefore, it is preferable to use the composition of the present invention that has a curability that allows sufficient curing even when a UV-LED is used.

<Discharge Means and Discharge Step>
The ejection step is a step of ejecting the active energy ray-curable composition of the present invention by an inkjet method.
The ejection means is a means for ejecting the active energy ray-curable composition of the present invention by an inkjet method.
The ejection step and the ejection method in the ejection means are not particularly limited as long as they are inkjet systems and can be appropriately selected depending on the purpose. Examples of the ejection method include a continuous ejection type and an on-demand type.
The on-demand type includes a piezoelectric type, a thermal type, an electrostatic type, and the like.

<Containment container>
The shape, size, material, etc. of the storage container of the present invention may be suitable for the application and usage, and are not particularly limited. However, it is preferable that the container is made of a light-blocking material that does not transmit light, or that the container is covered with a light-blocking sheet or the like.
The container means a container in which the composition of the present invention is contained, and is suitable for use in the above-mentioned <Application of the composition>. For example, when the composition of the present invention is used for ink, the container containing the ink can be used as an ink cartridge or ink bottle, and it is not necessary to directly touch the ink during ink transport or ink replacement, and it is possible to prevent the staining of hands and clothes. In addition, it is possible to prevent the inclusion of foreign matter such as dust into the ink.

In the manufacturing method of the present invention, the ejection step and the irradiation step are repeated in sequence to produce a three-dimensional object of a desired shape.

As a three-dimensional modeling apparatus for forming a three-dimensional object using the composition of the present invention, a known one can be used, and is not particularly limited. For example, the three-dimensional modeling apparatus may be one equipped with a means for storing, supplying, and discharging the composition, and an active energy ray irradiation means.
The present invention also includes a cured product obtained by curing the composition, and a molded product obtained by processing a structure in which the cured product is formed on a substrate.
The molded product is, for example, a product obtained by subjecting a cured product or structure formed into a sheet or film shape to molding processing such as heat stretching or punching, and is suitably used for applications requiring molding after surface decoration, such as meters and operation panel of automobiles, office automation equipment, electric and electronic equipment, cameras, etc.
The substrate is not particularly limited and can be appropriately selected depending on the purpose. Examples of the substrate include paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics, and composite materials thereof. From the viewpoint of processability, a plastic substrate is preferred.

The following describes a method and an apparatus for forming a three-dimensional object when the active energy ray-curable composition of the present invention is used as a model part forming material. However, the uses of the active energy ray-curable composition of the present invention are not limited to these embodiments.

--Image forming apparatus and image forming method--
FIG. 1 shows an example of an image forming apparatus equipped with an ink-jet ejection means.
The image forming apparatus 20 includes a supply roll 21, a recording medium 22, color printing units 23 (23a, 23b, 23c, 23d), light sources 24 (24a, 24b, 24c, 24d), a processing unit 25, and a print take-up roll 26. The color printing units 23a, 23b, 23c, 23d, each of which is equipped with an ink cartridge and a discharge head for each color of active energy ray curable ink of yellow, magenta, cyan, and black, discharge ink onto the recording medium 22 supplied from the supply roll 21. After that, the ink is cured by irradiating the ink with active energy rays from the light sources 24a, 24b, 24c, 24d for curing the ink, thereby forming a color image. The recording medium 22 is then transported to the processing unit 25 and the print take-up roll 26.

Each of the printing units 23a, 23b, 23c, and 23d may be provided with a heating mechanism so that the ink is liquefied in the ink ejection section.
The image forming apparatus 20 may be provided with a mechanism for cooling the recording medium to approximately room temperature by contact or non-contact, as necessary.
The recording medium 22 is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include paper, film, metal, and composite materials thereof, and may be in the form of a sheet. The recording medium 22 may be configured to allow only one-sided printing or to allow both-sided printing.
Furthermore, the irradiation of active energy rays from the light sources 24a, 24b, and 24c may be weakened or omitted, and after printing multiple colors, the active energy rays may be irradiated from the light source 24d. This can save energy and reduce costs.

As an inkjet recording method, either a serial method in which the head is moved to eject ink onto the recording medium, which moves intermittently according to the width of the ejection head, or a line method in which the recording medium is moved continuously and ink is ejected onto the recording medium from a head held in a fixed position, can be used.

Recorded items recorded with the active energy ray-curable ink made of the composition of the present invention include not only items printed on smooth surfaces such as ordinary paper or resin film, but also items printed on uneven printing surfaces and printing surfaces made of various materials such as metals and ceramics. In addition, by laminating two-dimensional images, it is also possible to form images with a partially three-dimensional effect (images that are two-dimensional and three-dimensional) or three-dimensional objects.

-Image forming apparatus and image forming method (three-dimensional image)-
FIG. 2 is a schematic diagram showing an example of another image forming apparatus (a three-dimensional image forming apparatus) according to the present invention.
The image forming device 39 has a discharge head unit 30 for a model, discharge head units 31 and 32 for a support, ultraviolet irradiation means 33 and 34, a three-dimensional model 35, a support stacking section 36, a model support base 37, and a stage 38. Using a head unit (movable in the AB direction) in which inkjet heads are arranged, a first composition for forming a three-dimensional model is discharged from the discharge head unit 30 for a model, and a second composition for forming a support is discharged from the discharge head units 31 and 32 for a support, respectively, onto the model support base 37. The first composition and the second composition are irradiated with active energy rays irradiated from the ultraviolet irradiation means 33 and 34, and cured to form a first model and a second model (not shown). A series of steps from discharge to curing are repeated multiple times according to the number of layers while lowering a stage 38 movable in the vertical direction, thereby producing a three-dimensional model 35 and a support stacking section 36. Thereafter, the support stacking section 36 is removed as necessary.
In addition, in FIG. 2, only one ejection head unit 30 for object is provided, but two or more may be provided.

[Cured product]
The cured product of the present invention can be obtained by irradiating the active energy ray-curable composition of the present invention with active energy rays.
The cured product of the present invention is a two- or three-dimensional image.
The two-dimensional or three-dimensional image is formed by applying either the active energy ray-curable composition of the present invention or an active energy ray-curable ink comprising the composition of the present invention onto a substrate and curing the applied image.
The two-dimensional or three-dimensional images include not only those printed on smooth surfaces such as ordinary paper or resin film, but also those recorded on recording surfaces having unevenness or those made of various materials such as metals or ceramics.
Examples of the two-dimensional image include characters, symbols, figures, or combinations thereof, and solid images.
The three-dimensional image may be, for example, a three-dimensional object.

In the process for producing the three-dimensional object, the average thickness of the cured product formed at one time is not particularly limited and may be appropriately selected depending on the purpose, but is preferably 10 μm or more.
The two-dimensional or three-dimensional image is preferably cured using light from a light-emitting diode having an active energy ray irradiation dose of 500 mJ/cm ² or less.

The extensibility of the cured product in the present invention is preferably 50% or more, and more preferably 100% or more, when expressed as the ratio of (length after tensile test - length before tensile test) / (length before tensile test) at 180°C.

[Decorative body]
The decorative body is formed by providing a surface decoration made of the cured product of the present invention on a substrate.
The substrate is not particularly limited and can be appropriately selected depending on the purpose. Examples of the substrate include paper, thread, fiber, cloth, leather, metal, plastic, glass, wood, ceramics, and composite materials thereof. From the viewpoint of processability, plastic is preferred.

The following describes examples of the present invention, but the present invention is not limited to these examples.

<Constituents of the composition>
The abbreviations, compound names, manufacturer names, and product names of the raw materials used in the preparation of the active energy ray-curable composition of the present invention are shown in Tables 1-1, 1-2, and 1-3.
The non-commercially available raw materials were synthesized by the methods shown in Synthesis Examples 1 to 7.
The synthesized compounds were identified by nuclear magnetic resonance spectroscopy (apparatus used: "JNM-ECX500" manufactured by JEOL Ltd.), and the purity was measured by gas chromatography (apparatus used: "GCMS-QP2010 Plus" manufactured by Shimadzu Corporation). These chemical analyses were performed by standard methods.

<Measurement of Glass Transition Temperature (Tg)>
For the polymerization of the monofunctional monomer, the monomer weighed out in a DSC sample pan was irradiated four times with a metal halide lamp (manufactured by Ushio Inc.) at 0.5 J/cm ² , and the obtained polymer was subjected to DSC measurement.
The DSC used was a DSC120U manufactured by Seiko Instruments, and the measurement was performed at a temperature range of 30° C. to 300° C. with a temperature rise rate of 2.5° C. per minute.

(Synthesis Example 1)
<Synthesis of N-acryloyl-N-methylglycine methyl ester (A-5)>
0.30 mol of N-methylglycine methyl ester hydrochloride (Sigma-Aldrich Japan, LLC, reagent), 0.45 mol of potassium carbonate (Kanto Chemical Co., Ltd., reagent), and 400 mL of water were mixed with stirring at 0 to 10°C, and 0.33 mol of acrylic acid chloride (Wako Pure Chemical Industries, Ltd., reagent) was slowly added dropwise while maintaining the temperature. After the dropwise addition, the mixture was extracted three times with 400 mL of ethyl acetate (Kanto Chemical Co., Ltd., reagent), and the ethyl acetate layer was combined and washed once with 400 mL of water. The ethyl acetate was distilled off under reduced pressure at 40°C to obtain 0.20 mol of the target N-acryloyl-N-methylglycine methyl ester (A-5) as an almost colorless and transparent liquid. The purity was 98.3% by mass.
The molecular weight of N-acryloyl-N-methylglycine methyl ester (A-5) is 157.2 and is a known compound (CAS Registry Number 72065-23-7).

(Synthesis Example 2)
<Synthesis of N-acryloyl-N-isopropylglycine isopropyl ester (A-6)>
The same procedure as in Synthesis Example 1 was repeated except that N-isopropylglycine isopropyl ester hydrochloride was used instead of N-methylglycine ethyl ester hydrochloride (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) in Synthesis Example 1, and 0.22 mol of the target N-acryloyl-N-isopropylglycine isopropyl ester (A-6) was obtained as a nearly colorless and transparent liquid. The purity was 98.5% by mass.
The molecular weight of N-acryloyl-N-isopropylglycine isopropyl ester (A-6) was 213.3.

(Synthesis Example 3)
<Synthesis of N-acryloyl-N-isopropylglycine methyl ester (A-7)>
The same procedure as in Synthesis Example 1 was repeated except that N-methylglycine methyl ester hydrochloride was replaced with N-methylglycine isopropyl ester hydrochloride (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) in Synthesis Example 1, and 0.22 mol of the target N-acryloyl-N-isopropylglycine isopropyl ester (A-7) was obtained as an almost colorless, transparent liquid. The purity was 98.5% by mass.
The molecular weight of N-acryloyl-N-isopropylglycine methyl ester (A-7) was 185.2.

(Synthesis Example 4)
<Synthesis of N-acryloyl-N-methylalanine methyl ester (A-8)>
The same procedure as in Synthesis Example 1 was repeated except that N-methylglycine methyl ester hydrochloride was replaced with N-methylalanine methyl ester hydrochloride (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) to obtain 0.22 mol of the target N-acryloyl-N-methylalanine methyl ester (A-8) as a nearly colorless and transparent liquid. The purity was 98.5% by mass.
The molecular weight of N-acryloyl-N-methylalanine methyl ester (A-8) was 171.2.

(Synthesis Example 5)
<Synthesis of N-acryloyl-N-methylglycine isopropyl ester (A-9)>
The same procedure as in Synthesis Example 1 was repeated except that N-methylglycine methyl ester hydrochloride was replaced with N-methylglycine isopropyl ester hydrochloride (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) in Synthesis Example 1, and 0.22 mol of the target N-acryloyl-N-methylglycine isopropyl ester (A-9) was obtained as an almost colorless and transparent liquid. The purity was 98.5% by mass.
The molecular weight of N-acryloyl-N-methylglycine isopropyl ester (A-9) was 185.2.

(Synthesis Example 6)
<Synthesis of N-acryloyl-N-methylalanine isopropyl ester (A-10)>
The same procedure as in Synthesis Example 1 was repeated except that N-methylglycine methyl ester hydrochloride was replaced with N-methylalanine isopropyl ester hydrochloride (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.) to obtain 0.22 mol of the target N-acryloyl-N-methylalanine isopropyl ester (A-10) as a nearly colorless, transparent liquid. The purity was 98.5% by mass.
The molecular weight of N-acryloyl-N-methylalanine isopropyl ester (A-10) was 199.3.

(Synthesis Example 7)
<Synthesis of ethyl N-acryloylpiperidine-4-carboxylate (A-11)>
The same procedure as in Synthesis Example 1 was repeated except that N-methylglycine methyl ester hydrochloride was replaced with ethyl piperidine-4-carboxylate (a reagent manufactured by Tokyo Chemical Industry Co., Ltd.), and 0.27 mol of the target ethyl N-acryloylpiperidine-4-carboxylate (A-11) was obtained as a nearly colorless and transparent liquid. The purity was 99.2% by mass.
The molecular weight of N-acryloylpiperidine-4-ethyl carboxylate (A-11) is 211.3 and it is a known compound (CAS Registry Number 845907-79-1).

Example 1
<Preparation of Composition>
20.0 mass% of A-1, 20.0 mass% of B-1, 46.8 mass% of C-1, 3.0 mass% of D-1, 3.0 mass% of F-2, 7.0 mass% of F-3, 0.1 mass% of polymerization inhibitor (G), and 0.1 mass% of surfactant (H) were added in this order and stirred for 2 hours. After visually confirming that no dissolved residue remained, the mixture was filtered through a membrane filter to remove coarse particles, thereby preparing the composition of Example 1.

(Examples 2 to 30 and Comparative Examples 1 to 20)
The compositions of Examples 2 to 30 and Comparative Examples 1 to 20 were prepared in the same manner as in Example 1, except that the compositions and contents (mass%) in Tables 2 to 6 were changed as shown in Tables 2 to 6 below.

Next, the viscosity at 25°C was measured for the compositions of Examples 1 to 30 and Comparative Examples 1 to 20 as follows. The results are shown in Tables 7 to 11.

<Measurement of Viscosity>
Measurements were performed using a cone-plate type rotational viscometer VISCOMETER TVE-22L manufactured by Toki Sangyo Co., Ltd., using a cone rotor (1°34′×R24), at a rotation speed of 50 rpm, and adjusting the temperature of the thermostatic circulating water to 25° C. A VISCOMATE VM-150III was used to adjust the temperature of the circulating water.

<Formation of Printed Image by Inkjet>
The compositions of Examples 1 to 30 and Comparative Examples 1 to 20 were each filled into a plastic composition storage container, and incorporated into an image forming apparatus equipped with an inkjet head (MH5440, manufactured by Ricoh Company, Ltd.) as an ejection means, a UV-LED (LED ZERO, manufactured by Integration Technology Japan, wavelength 395 nm, illuminance at the irradiation surface 1.0 W/cm ² ) as an active energy ray irradiation means, a controller for controlling ejection, and a supply path from the composition storage container to the inkjet head.
The temperature of the inkjet head was appropriately adjusted so that the viscosity of the composition was 10 mPa·s to 12 mPa·s, and the composition was ink-jet-discharged to a film thickness of 10 μm onto a commercially available PET film (manufactured by Toyobo Co., Ltd., "Cosmoshine A4100", thickness 188 μm), which is a general-purpose film material, and ultraviolet light was irradiated using a UV-LED to produce a printed image.

<Evaluation of Curability>
The accumulated amount of irradiation light required for curing the compositions of Examples 1 to 30 and Comparative Examples 1 to 20 was determined, and the results are shown in Tables 7 to 11.
In the present invention, the coating film obtained by irradiating with active energy rays is judged to be cured when it reaches a state where it does not feel sticky when touched with a finger. In addition, it is judged that the coating film is usable when the cumulative amount of irradiation light required for curing is 2.0 J/ ^cm2 or less.

<Evaluation of hardness>
For the cured products obtained by curing the compositions of Examples 1 to 30 and Comparative Examples 1 to 20, the pencil hardness was measured by a scratch hardness (pencil method) test using a scratch pencil hardness TQC WW tester (load 750 g) manufactured by COTEC Corporation in accordance with JIS K5600-5-4 to evaluate the "hardness". The results are shown in Tables 7 to 11. Note that a hardness of HB or higher was deemed to be practical.
The scratch hardness test was carried out using a set of wooden drafting pencils (6B, 5B, 4B, 3B, 2B, B, HB, F, H, 2H, 3H, 4H, 5H, 6H) manufactured by Mitsubishi Pencil Co., Ltd., and a pencil sharpener. The pencil sharpener was a special one that scraped off only the wood part of the pencil while leaving the cylindrical core of the pencil intact.

<Evaluation of Adhesion>
The adhesion between the cured products obtained by curing the compositions of Examples 1 to 30 and Comparative Examples 1 to 20 and the substrate was evaluated by measuring the adhesion by the cross-cut method specified in JIS-K-5600-5-6 on a solid coating film obtained by curing a commercially available tin plate (test piece tin plate, 200 x 50 x 0.3 mm) as a general-purpose metal material widely used as an industrial material, ejecting an active energy ray curable composition onto the tin plate by inkjet printing, and irradiating the composition with light using a UV irradiator (LH6 (D bulb), manufactured by Fusion Systems Japan Co., Ltd.). The results are shown in Tables 7 to 11.
Other substrates used were a PET (polyethylene terephthalate) film (Toyobo Co., Ltd., "Cosmoshine A4100", thickness 188 μm), a PP (polypropylene) film (Toyobo Co., Ltd., "Pylen Film-OT", thickness 20 μm), a PC (polycarbonate) plate (Mitsubishi Engineering Plastics Corporation, "Iupilon NF-2000C transparent", thickness 0.5 mm), an acrylic plate (Sumitomo Acrylic Sales Co., Ltd., "Sumipex E000", thickness 1 mm), and a glass plate (Matsunami Glass Industry Co., Ltd., "Large slide water edge polished t1.3 (S9213)", thickness 1 mm).
--Evaluation criteria--
A: No peeling was observed. B: Only small peeling of 5% or more and less than 20% was observed. C: Peeling of 20% or more and less than 50% of the total was observed. D: Peeling of 50% or more was observed.

<Evaluation of stretchability>
The composition of the present invention was cured into a dumbbell No. 6 shape (thickness 1 mm) and the "stretchability" was evaluated by measuring the ratio of elongation at the center of the dumbbell sample before the test and after the test at which it broke using an AGS-X universal mechanical testing machine in accordance with JIS K 7161 (Testing methods for tensile properties of plastics, Part 1: General rules). A stretch rate of 50% or more was deemed to be usable. The results are shown in Tables 7 to 11.
--Evaluation criteria--
A: Stretch ratio is 100% or more. B: Stretch ratio is 50% or more but less than 100%. C: Stretch ratio is 10% or more but less than 50%. D: Stretch ratio is less than 10%.

（前記一般式（１）におけるＲは、炭素数１～６のアルキル基を表す。）
＜２＞前記アクリルアミド化合物（Ａ）及び前記一般式（１）で表される重合性化合物（Ｂ）の組成物おける含有量の和が、２０．０質量％以上６０．０質量％以下である、＜１＞に記載の活性エネルギー線硬化型組成物である。
＜３＞前記単官能重合性化合物（Ｃ）の組成物における含有量が、４０．０質量％以上８０．０質量％以下である、＜１＞から＜２＞のいずれかに記載の活性エネルギー線硬化型組成物である。
＜４＞前記アクリルアミド化合物（Ａ）が、アクリロイルモルフォリン又は下記一般式（２）で表される化合物である、＜１＞から＜３＞のいずれかに記載の活性エネルギー線硬化型組成物である。

前記一般式（２）におけるＲ^１は、炭素数１～６のアルキル基を表し、Ｘは炭素数１～６のアルキレン基を表し、Ｙは下記一般式（３）及び下記一般式（４）のいずれかを表す。

前記一般式（３）におけるＲ^２は、炭素数１～１０のアルキル基を表し、＊は前記Ｘとの結合部位を表す。

前記一般式（４）におけるＲ^３は、炭素数１～１０のアルキル基を表し、＊は前記Ｘとの結合部位を表す。
＜５＞前記単官能重合性化合物（Ｃ）がテトラヒドロフルフリルアクリレート、テトラヒドロフルフリルアルコール アクリル酸多量体エステル、（２－メチル－２－エチル－１，３－ジオキソラン－４－イル）メチルアクリレート、環状トリメチロールプロパンホルマールアクリレート、（３－エチルオキセタン－３－イル）メチルアクリレート、及びγ－ブチロラクトンアクリレートのいずれかである、＜１＞から＜４＞のいずれかに記載の活性エネルギー線硬化型組成物である。
＜６＞有機溶剤を含まない＜１＞から＜５＞のいずれかに記載の活性エネルギー線硬化型組成物である。
＜７＞＜１＞から＜６＞のいずれかに記載の活性エネルギー線硬化型組成物を含有することを特徴とする活性エネルギー線硬化型インクである。
＜８＞インクジェット用である＜７＞に記載の活性エネルギー線硬化型インクである。
＜９＞＜１＞から＜６＞のいずれかに記載の活性エネルギー線硬化型組成物、及び＜７＞から＜８＞のいずれかに記載の活性エネルギー線硬化型インクのいずれかを容器中に収容されてなることを特徴とする収容容器である。
＜１０＞＜１＞から＜６＞のいずれかに記載の活性エネルギー線硬化型組成物、及び＜７＞から＜８＞のいずれかに記載の活性エネルギー線硬化型インクの少なくともいずれかを容器中に収容する収容部と、活性エネルギー線を照射するための照射手段と、を有することを特徴とする２次元または３次元の像形成装置である。
＜１１＞前記照射手段が、波長３６５～４０５ｎｍにピークを有する紫外線を照射するＵＶ－ＬＥＤである、＜１０＞に記載の像形成装置である。
＜１２＞＜１＞から＜６＞のいずれかに記載の活性エネルギー線硬化型組成物、及び＜７＞から＜８＞のいずれかに記載の活性エネルギー線硬化型インクの少なくともいずれかに活性エネルギー線を照射して２次元又は３次元の像を形成することを特徴とする像形成方法である。
＜１３＞前記活性エネルギー線が波長３６５～４０５ｎｍにピークを有する紫外線であり、前記紫外線がＵＶ－ＬＥＤによって照射される、＜１２＞に記載の像形成方法である。
＜１４＞＜１＞から＜６＞のいずれかに記載の活性エネルギー線硬化型組成物、及び＜７＞から＜８＞のいずれかに記載の活性エネルギー線硬化型インクの少なくともいずれかに活性エネルギー線を照射して形成されることを特徴とする硬化物である。
＜１５＞基材上に＜１４＞に記載の硬化物からなる表面加飾が施されてなることを特徴とする加飾体である。 For example, aspects of the present invention are as follows.
<1> An acrylamide compound,
an acrylamide compound (A) having a glass transition temperature (Tg) of 50° C. or higher after curing;
A polymerizable compound (B) represented by general formula (1),
A monofunctional polymerizable compound having a heterocycle,
A monofunctional polymerizable compound (C) having a Tg of 30° C. or less after curing;
and (D) at least one of a urethane acrylate oligomer and an acrylate oligomer having a dendrimer structure,
The content of the oligomer (D) in the composition is 5.0 mass % or less.

(In the general formula (1), R represents an alkyl group having 1 to 6 carbon atoms.)
<2> The active energy ray-curable composition according to <1>, wherein a sum of the contents of the acrylamide compound (A) and the polymerizable compound (B) represented by general formula (1) in the composition is 20.0 mass% or more and 60.0 mass% or less.
<3> The active energy ray-curable composition according to any one of <1> and <2>, wherein the content of the monofunctional polymerizable compound (C) in the composition is 40.0 mass% or more and 80.0 mass% or less.
<4> The active energy ray-curable composition according to any one of <1> to <3>, wherein the acrylamide compound (A) is acryloylmorpholine or a compound represented by the following general formula (2):

In the general formula (2), R ¹ represents an alkyl group having 1 to 6 carbon atoms, X represents an alkylene group having 1 to 6 carbon atoms, and Y represents any one of the following general formulas (3) and (4).

In the general formula (3), R ² represents an alkyl group having 1 to 10 carbon atoms, and * represents the bonding site with X.

In the general formula (4), R ³ represents an alkyl group having 1 to 10 carbon atoms, and * represents the bonding site with X.
<5> The active energy ray-curable composition according to any one of <1> to <4>, wherein the monofunctional polymerizable compound (C) is any one of tetrahydrofurfuryl acrylate, tetrahydrofurfuryl alcohol acrylic acid polymer ester, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate, cyclic trimethylolpropane formal acrylate, (3-ethyloxetan-3-yl)methyl acrylate, and γ-butyrolactone acrylate.
<6> The active energy ray-curable composition according to any one of <1> to <5>, which does not contain an organic solvent.
<7> An active energy ray-curable ink, comprising the active energy ray-curable composition according to any one of <1> to <6>.
<8> The active energy ray-curable ink according to <7>, which is for inkjet use.
<9> A storage container, comprising: the active energy ray-curable composition according to any one of <1> to <6>; and the active energy ray-curable ink according to any one of <7> to <8>.
<10> A two-dimensional or three-dimensional image forming device comprising: a container for housing at least one of the active energy ray-curable composition according to any one of <1> to <6> and the active energy ray-curable ink according to any one of <7> to <8>; and an irradiation means for irradiating with active energy rays.
<11> The image forming apparatus according to <10>, wherein the irradiation means is a UV-LED that irradiates ultraviolet light having a peak wavelength in the range of 365 to 405 nm.
<12> An image forming method, comprising irradiating at least one of the active energy ray-curable composition according to any one of <1> to <6> and the active energy ray-curable ink according to any one of <7> to <8> with active energy rays to form a two-dimensional or three-dimensional image.
<13> The image forming method according to <12>, wherein the active energy rays are ultraviolet rays having a peak wavelength in the range of 365 to 405 nm, and the ultraviolet rays are irradiated by a UV-LED.
<14> A cured product formed by irradiating at least one of the active energy ray-curable composition according to any one of <1> to <6> and the active energy ray-curable ink according to any one of <7> to <8> with active energy rays.
<15> A decorated body, comprising a substrate and a surface decoration made of the cured product according to <14>.

The active energy beam curable composition described in any one of <1> to <6>, the active energy beam curable ink described in any one of <7> to <8>, the container described in <9>, the image forming method described in any one of <10> to <13>, the cured product described in <14>, and the decorative body described in <15> can solve the conventional problems and achieve the object of the present invention.

1. Storage pool (containment area)
3 Movable stage 4 Active energy rays 5 Composition 6 Cured layer 20 Image forming device 21 Supply roll 22 Recording medium 23a, 23b, 23c, 23d Printing unit 24a, 24b, 24c, 24d Light source 25 Processing unit 26 Printed matter winding roll 30 Discharge head unit for object 31, 32 Discharge head unit for support 33, 34 Ultraviolet ray irradiation means 35 Three-dimensional object 36 Support layer stacking unit 37 Object support base 38 Stage

Patent No. 5606817 Patent No. 2938808 JP 2014-205839 A JP 2019-189855 A JP 2019-143057 A JP 2013-91788 A

Claims (13)

An acrylamide compound,
an acrylamide compound (A) having a glass transition temperature (Tg) of 50° C. or higher after curing;
A polymerizable compound (B) represented by general formula (1),
A monofunctional polymerizable compound having a heterocycle,
A monofunctional polymerizable compound (C) having a Tg of 30° C. or less after curing;
and (D) at least one of a urethane acrylate oligomer and an acrylate oligomer having a dendrimer structure,
the sum of the contents of the acrylamide compound (A) and the polymerizable compound (B) represented by the general formula (1) in the composition is 20.0 mass% or more and 60.0 mass% or less,
The content of the monofunctional polymerizable compound (C) in the composition is 40.0% by mass or more and 60.0% by mass or less,
An active energy ray-curable composition, wherein the content of the oligomer (D) in the composition is 1.0 mass % or more and 5.0 mass % or less.

(In the general formula (1), R represents an alkyl group having 1 to 6 carbon atoms.) The active energy ray-curable composition according to claim 1 , wherein the acrylamide compound (A) is acryloylmorpholine or a compound represented by the following general formula (2):

In the general formula (2), R ¹ represents an alkyl group having 1 to 6 carbon atoms, X represents an alkylene group having 1 to 6 carbon atoms, and Y represents any one of the following general formulas (3) and (4).

In the general formula (3), R ² represents an alkyl group having 1 to 10 carbon atoms, and * represents the bonding site with X.

In the general formula (4), R ³ represents an alkyl group having 1 to 10 carbon atoms, and * represents the bonding site with X. The active energy ray-curable composition according to any one of claims 1 to 2, wherein the monofunctional polymerizable compound (C ) is any one of tetrahydrofurfuryl acrylate, tetrahydrofurfuryl alcohol acrylic acid polymer ester, (2-methyl-2-ethyl-1,3-dioxolan-4-yl)methyl acrylate, cyclic trimethylolpropane formal acrylate, (3-ethyloxetan-3-yl)methyl acrylate, and γ-butyrolactone acrylate. The active energy ray-curable composition according to any one of claims 1 to 3, which does not contain an organic solvent. 5. An active energy ray-curable ink comprising the active energy ray-curable composition according to claim 1. The actinic ray-curable ink according to claim 5 , which is for ink-jet use. A storage container, comprising: the active energy ray-curable composition according to any one of claims 1 to 4 ; and the active energy ray-curable ink according to any one of claims 5 to 6 . 10. A two-dimensional or three-dimensional image forming apparatus comprising: a container for housing at least one of the active energy ray-curable composition according to claim 1 and the active energy ray-curable ink according to claim 5 ; and an irradiation means for irradiating with active energy rays. 9. The image forming apparatus according to claim 8 , wherein the irradiation means is a UV-LED that irradiates ultraviolet light having a peak wavelength in the range of 365 to 405 nm. An image forming method, comprising irradiating at least one of the active energy ray-curable composition according to any one of claims 1 to 4 and the active energy ray-curable ink according to any one of claims 5 to 6 with active energy rays to form a two-dimensional or three-dimensional image. The active energy rays are ultraviolet rays having a peak wavelength of 365 to 405 nm,
The imaging method according to claim 10 , wherein the ultraviolet light is emitted by a UV-LED. A cured product formed by irradiating at least one of the active energy ray-curable composition according to any one of claims 1 to 4 and the active energy ray-curable ink according to any one of claims 5 to 6 with active energy rays. A decorated body, comprising a substrate and a surface decoration comprising the cured product according to claim 12 .

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