JP2006282873A - Ink composition, image-forming method using the same and recorded matter obtained using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink composition that can form an image on various recording media and is excellent in curability and stability, and to provide, using the ink composition, an image-forming method capable of forming an image exhibiting a good adhesive property and having no stickiness and recorded matter. <P>SOLUTION: The ink composition comprises a monomer having a ring-opening photopolymerizable group and a nitrogen-containing heterocyclic structure. The image forming method comprises using the same. The recorded matter is obtained using the same. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink composition, and an image forming method and a recorded matter using the same, and more specifically, an ink composition that can be cured by polymerization after recording and is suitable for recording a robust image, and The present invention relates to the used image forming method and recorded matter.

  Conventionally, water-based ink-jet inks have had problems such as low water resistance when printed on plain paper, and blurring easily occurs. Also, water-based ink-jet inks cannot be printed when printed on non-water-absorbing recording media such as plastics due to poor adhesion of the ink liquid, and the printing of the solvent is extremely slow. Immediately after that, there was a problem that it was necessary to dry without overlapping the recorded material.

  On the other hand, an ultraviolet curable ink using a polyfunctional monomer excellent in adhesiveness with a recording medium has been developed as suitable for printing on a non-water-absorbing recording medium. However, these inks are slow to dry due to the water-dispersed ink, and are insufficient to form a full-color image. Further, in order to solve the drying property, a method using a volatile organic solvent as an ink solvent has been carried out. However, low-boiling solvents such as methyl ethyl ketone and ethanol, which are quick to dry, have a problem in odor.

On the other hand, an ink composition in which only a polymerizable monomer is used as an ink solvent and solidified by radiation after printing to eliminate a volatile component, and an inkjet image forming method using the same have been developed. Examples of such ink include ink containing a monomer having a polymerizable group and an oil-soluble dye (see, for example, Patent Documents 1 to 3), and light containing a photopolymerizable compound and a photopolymerization initiator. A polymerizable composition (for example, see Patent Document 4) and a curable composition by photocationic polymerization (for example, see Patent Documents 5 to 7) such as oxirane monomer, oxetane monomer and vinyl ether have been proposed. However, depending on the type of the base material, there is a problem that the cured ink may be peeled off from the base material and the adhesiveness may be poor.
JP 2003-221528 A JP 2003-221532 A JP 2003-221530 A JP 2001-222105 A JP 2000-169552 A JP 2001-220526 A JP 2004-10625 A

  INDUSTRIAL APPLICABILITY The present invention is capable of forming an image on various recording media, an ink composition having excellent curability and stability, and an image forming method capable of forming a non-sticky image using the ink composition. And to provide records.

The problems of the present invention are solved by the following means.
<1> An ink composition comprising a monomer having a photo-ring-opening polymerizable group and a nitrogen-containing heterocyclic structure.

  <2> The ink composition according to <1>, wherein the photo-ring-opening polymerizable group is an oxirane group or an oxetane group.

  <3> The ink composition according to <1> or <2>, wherein the monomer has two or more photo-ring-opening polymerizable groups.

  <4> The ink composition according to <1> to <3>, wherein the nitrogen-containing heterocyclic structure of the monomer is a 5- to 8-membered ring.

（一般式（Ｉ）中、Ｑは−ＣＯＮ−と共に５〜８員環を形成しうる原子団を表す。Ｌは単結合または２価の連結基を表す。Ｙは前記光開環重合性基を表す。ｎは１または２を表し、ｍは１〜４の整数を表す。） <5> The ink composition according to <1> to <4>, wherein the monomer is represented by the following general formula (I).

(In the general formula (I), Q represents an atomic group capable of forming a 5- to 8-membered ring with -CON-. L represents a single bond or a divalent linking group. Y represents the photo-ring-opening polymerizable group. N represents 1 or 2, and m represents an integer of 1 to 4.)

  <6> The ink composition according to <1> to <5>, further including a colorant.

  <7> The ink composition according to <6>, wherein the colorant is a pigment or an oil-soluble dye.

  <8> The ink composition according to <1> to <7>, wherein the ink composition is for inkjet printing.

  <9> An image recording step of recording an image on a recording material using the ink composition of <1> to <7>, and an active energy ray on the image recorded on the recording material in the image recording step And an image curing step of irradiating and curing.

  <10> The image forming method according to <9>, wherein the image recording step records the image by inkjet recording in which the ink composition is discharged.

  <11> A recorded matter comprising the ink composition according to <1> to <8>.

According to the present invention, an image can be formed on various recording media, an ink composition excellent in curability and stability, and an image capable of forming an image with good adhesion and no stickiness using the ink composition. A forming method and recorded matter can be provided.
The ink composition of the present invention can be used for normal printing, and can be used not only for the production of a resist, a color filter, and an optical disc, but also for obtaining a sticky and non-sticky recorded matter. It is also useful as an optical modeling material.
Further, by applying the ink jet recording method, a high-quality image can be directly formed on a non-absorbable recording material based on digital data. Therefore, the ink composition of the present invention has a large area recording material. It is used suitably also for preparation of.

  Hereinafter, the ink composition of the present invention, and the image forming method and recorded matter using the ink composition will be described in detail.

<Ink composition>
The ink composition of the invention contains a monomer having a photo-ring-opening polymerizable group and a nitrogen-containing heterocyclic structure (hereinafter sometimes referred to as “monomer in the invention”). And
Since the ink composition of the present invention contains a monomer having a photo-ring-opening polymerizable group and a nitrogen-containing heterocyclic structure, the ink can be cured by light such as ultraviolet rays after ink ejection. Therefore, it is possible to form an image on various recording media such as a non-absorbing recording medium. In addition, since the ink composition of the present invention is excellent in curability and stability, it has good adhesion to a non-recording material and can form a non-sticky image.

  The ink composition of the present invention preferably contains a colorant in addition to the monomer in the present invention. In addition, the ink composition of the present invention can be constituted by using other components such as other polymerizable compounds and photopolymerization initiators and various additives, if necessary.

(Monomer having photo-ring-opening polymerizable group and nitrogen-containing heterocyclic structure)
The ink composition of the present invention contains a monomer having a photo-ring-opening polymerizable group and a nitrogen-containing heterocyclic structure (monomer in the present invention). Here, the “photo-ring-opening polymerizable group” means a group that can be polymerized by being opened by light. The “light” includes ultraviolet rays, infrared rays, and visible light.

Examples of the photo-ring-opening polymerizable group include an oxirane group, an oxetane group, and a cyclic carbonate group, and an oxirane group and an oxetane group are particularly preferable.
The nitrogen-containing heterocycle is preferably a 5- to 8-membered ring, more preferably a 5- or 6-membered ring. Examples of the nitrogen-containing heterocycle include 5-membered rings such as pyrrole, pyrroline, pyrrolidine, oxazole, isoxazole, thiazole, isothiazole, imidazole, imidazoline, imidazolidine, pyrazole, pyrazoline, pyrazolidine, triazole, furazane, and tetrazole; 6-membered rings such as pyrozine, piperidine, oxazine, morpholine, thiazine, pyridazine, pyrimidine, pyrazi, piperazine, triazine; 6,5 condensed rings such as indole, indoline, isoindole, benzoxazole, benzothiazole, indazole, benzimidazole; 6,6 condensed rings such as quinoline, isoquinoline, cinquinazoline, quinoxaline; and those in which the α-position —CH ₂ — of the N atom of these nitrogen-containing heterocycles is replaced by —CO—, and α , Β-position —CH═CH— is preferably replaced with —CO—CH ₂ —.

  The number of photo-ring-opening polymerizable groups possessed by the monomer in the present invention is preferably 1 to 6, and more preferably 2 to 4. Moreover, as molecular weight of the monomer in this invention, 100-2000 are preferable and 150-600 are more preferable.

  As a monomer in this invention, the compound represented by the following general formula (I) is preferable.

（一般式（Ｉ）中、Ｑは−ＣＯＮ−と共に５〜８員環を形成しうる原子団を表す。Ｌは単結合または２価の連結基を表す。Ｙは前記光開環重合性基を表す。ｎは１または２を表し、ｍは１〜４の整数を表す。）

(In the general formula (I), Q represents an atomic group capable of forming a 5- to 8-membered ring with -CON-. L represents a single bond or a divalent linking group. Y represents the photo-ring-opening polymerizable group. N represents 1 or 2, and m represents an integer of 1 to 4.)

In general formula (I), Q represents an atomic group capable of forming a 5- to 8-membered ring together with -CON-. Examples of the atomic group include —CH ₂ —, —CH═CH—, —O—, —S—, —NH—, —N═, —COO—, —NHCO—, —CO—, —SO _2. A combination of divalent groups represented by — and —CO— is preferred, and a combination of divalent groups selected from —CH ₂ —, —NH— and —NHCO— is more preferred. The hydrogen atom of the divalent group may be replaced by a substituent or -L- (Y) _m in the general formula (I).
The ring formed by Q and -CON- is particularly preferably a 5- or 6-membered ring. In this case, Q is preferably a combination of divalent groups selected from —CH ₂ —, —NH— and —NHCO—, and the hydrogen atom on the nitrogen atom of the divalent group is represented by formula (I). Those in which -L- (Y) _m is replaced are more preferred.

In general formula (I), L represents a single bond or a divalent linking group. The divalent linking group L represented by L is not particularly limited, but is preferably a substituted or unsubstituted alkylene group, arylene group, alkenylene group, aralkyl group, —O—, —S—, —COO—. , —N (R) CO—, —CO—, —SO ₂ —, —CO—, or a combination thereof. Here, R is a hydrogen atom, an alkyl group (C1-C10 alkyl group is preferable, for example, methyl, ethyl, propyl, butyl, octyl etc.) or an aryl group (C6-C10 aryl group is preferable). For example, phenyl, naphthyl, etc.). Particularly preferred divalent linking groups in L are alkylene groups (C1-C4 alkylene groups are preferred, such as methylene, ethylene, propylene, trimethylene, tetramethylene, etc.) and -O-. A divalent linking group is preferred.

  In general formula (I), Y represents the above-mentioned photo-ring-opening polymerizable group. N represents 1 or 2, and m represents an integer of 1 to 4. m × n is preferably in the range of 1 to 4, particularly preferably 2.

  Q, L and Y in the general formula (I) may have a substituent. Examples of preferred substituents include halogen atoms (F, Cl, Br, I), cyano groups, alkoxy groups (eg, methoxy, ethoxy, methoxyethoxy, etc.), aryloxy groups (eg, phenoxy, etc.), alkylthio groups (eg, , Methylthio, ethylthio, etc.), acyl groups (eg, acetyl, propionyl, benzoyl, etc.), sulfonyl groups (eg, methanesulfonyl, benzenesulfonyl, etc.), acyloxy groups (eg, acetoxy, benzoyloxy, etc.), sulfonyloxy groups (eg, , Methanesulfonyloxy, toluenesulfonyloxy, etc.), phosphonyl groups (eg, diethylphosphonyl, etc.), amide groups (eg, acetylamino, benzoylamide, etc.), carbamoyl groups (eg, N, N-dimethylcarbamoyl, -Phenylcarbamoyl etc.), alkyl groups (eg methyl, ethyl, propyl, isopropyl, cyclopropyl, butyl, 2-carboxyethyl, benzyl etc.), aryl groups (eg phenyl, toluyl etc.), heterocyclic groups (eg Pyridyl, imidazolyl, furanyl, etc.), alkenyl groups (eg, vinyl, 1-propenyl, etc.) and the like.

  Specific examples of the monomer in the present invention (monomers (1-1) to (1-24)) are shown below, but the present invention is not limited thereto.

  The content of the monomer in the present invention is preferably 0.5 to 95% by mass, more preferably 5 to 95% by mass, and particularly preferably 5 to 50% by mass with respect to the total amount (total mass) of the ink composition.

  The monomer in the present invention is polymerized or copolymerized upon irradiation with an active energy ray by the action of a photo (cation) polymerization initiator described later, and is cured itself, and the composition constituting the image is cured to produce light, ozone, or rubbing. It is possible to improve the fastness to the above.

(Polymerizable compound)
In the ink composition of the present invention, other cationic polymerizable compounds may be used in combination with the above-mentioned monomers in the present invention. These can be arbitrarily selected for the purpose of adjusting the degree of polymerization and the physical properties of the ink composition. Among these, oxirane compounds, oxetane compounds, vinyl ethers, styrenes, and the like are preferable from the viewpoint of polymerization rate and versatility. These may be used alone or in combination of two or more. Examples are shown below.

-Cationically polymerizable compound-
As the cationic polymerizable compound, various known cationic polymerizable monomers known as photo cationic polymerizable monomers can be used. Examples of the cationic polymerizable monomer include JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-310937, and JP-A-2001-220526. And oxetane compounds, oxirane compounds, vinyl ethers, and styrenes.

--Oxetane group-containing / oxirane group-containing compounds--
The ink composition of the present invention preferably contains at least one oxetane group-containing compound and / or at least one oxirane group-containing compound as the polymerizable compound, and preferably includes at least one oxetane group-containing compound, It is more preferable to include at least one oxirane group-containing compound. These compounds are polymerized upon irradiation with active energy rays by the action of a photopolymerization initiator, which will be described later, and cure themselves, so that the curing reaction can be carried out in a short time. It is particularly effective for preventing fading in an image at the time and after curing, and can form an image having excellent hue (hue), color density, and sharpness, and light resistance comparable to that of a pigment.

  When the oxetane group-containing compound (p) and the oxirane group-containing compound (q) are used in combination, the content ratio (mass ratio) p / q is 50 in that the light resistance of the image after curing can be more effectively improved. / 50 to 95/5 is preferable, and 67/33 to 90/10 is particularly preferable.

<Oxetane group-containing compound>
The oxetane group-containing compound can be appropriately selected from compounds containing at least one oxetane group (oxetanyl group) in the molecule.
For example, as a compound having one oxetane group in the molecule, a compound represented by the following general formula (1-a) is preferable, and as a compound having two or more oxetane groups in the molecule, the following general formula ( The compounds represented by 1-b) are preferred.

First, the oxetane group-containing compound represented by the general formula (1-a) will be described.
In the general formula (1-a), Z represents an oxygen atom or a sulfur atom, and an oxygen atom is preferable. R ^1a is a hydrogen atom, a fluorine atom, an alkyl group having 1 to 6 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, a butyl group, etc.), a fluoroalkyl group having 1 to 6 carbon atoms, an allyl group, an aryl Represents a group, a furyl group or a thienyl group, preferably an alkyl group having 1 to 6 carbon atoms (particularly a methyl group or an ethyl group).

R ^2a is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, or a butyl group), an alkenyl group having 1 to 6 carbon atoms (for example, a 1-propenyl group, 2- Propenyl group, 2-methyl-1-propenyl group, 2-methyl-2-propenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group, etc.), aryl group (for example, phenyl group, benzyl group, fluoro A benzyl group, a methoxybenzyl group, a phenoxyethyl group, etc.), an alkylcarbonyl group having 1 to 6 carbon atoms (for example, a propylcarbonyl group, a butylcarbonyl group, a pentylcarbonyl group, etc.), an alkoxycarbonyl group having 1 to 6 carbon atoms ( For example, ethoxycarbonyl group, propoxycarbonyl group, butyroxycarbonyl group, etc.), C1-C6 alkoxycarbamoyl group (example) If, ethoxy carbamoyl group, propoxy carbamoyl group, butyl pentyl b alkoxy carbamoyl group), representing the like.

Of the oxetane group-containing compounds represented by the general formula (1-a), R ^1a is a lower alkyl group (particularly an ethyl group), and R ^2a is a hydrogen atom, a butyl group, a phenyl group, or a benzyl group. An embodiment in which Z is an oxygen atom is particularly preferred. Here, the lower alkyl group refers to an alkyl group having 1 to 3 carbon atoms (the same applies hereinafter).
In addition, the oxetane group-containing compound represented by the general formula (1-a) may be used alone or in combination of two or more.

Next, the oxetane group-containing compound represented by the general formula (1-b) will be described.
In the general formula (1-b), m represents 2, 3 or 4, Z represents an oxygen atom or a sulfur atom, and Z is preferably an oxygen atom.

In the general formula (1-b), R ^1b is a hydrogen atom, a fluorine atom, an alkyl group having 1 to 6 carbon atoms (eg, a methyl group, an ethyl group, a propyl group, a butyl group), a phenyl group, or a carbon number. 1 to 6 fluoroalkyl groups, allyl groups, aryl groups, or furyl groups are represented.

R ^2b represents a linear or branched alkylene group having 1 to 12 carbon atoms, a linear or branched poly (alkyleneoxy) group, or a divalent group selected from the group consisting of the following general formulas (3), (4) and (5). Represents a group of

The linear or branched alkylene group having 1 to 12 carbon atoms is preferably a group represented by the following general formula (2). R ³ in the following general formula (2) represents a lower alkylene group such as a methylene group, an ethylene group, or a propylene group.

In the general formula (3), n represents 0 or an integer of 1 to 2000, and R ⁴ represents an alkyl group having 1 to 10 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, A hexyl group, a heptyl group, an octyl group, a nonyl group, or the like) or a group selected from groups represented by the following general formula (6). R ⁵ represents an alkyl group having 1 to 10 carbon atoms (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, etc.), preferably a methyl group It is.

In the general formula (6), j represents 0 or an integer of 1 to 100, and R ⁶ represents an alkyl group having 1 to 10 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, A hexyl group, a heptyl group, an octyl group, a nonyl group, etc.), preferably a methyl group.

In the general formula (4), R ⁷ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, Nonyl groups, etc.), C1-C10 alkoxy groups (eg, methoxy, ethoxy, propoxy, butoxy, pentoxy, etc.), halogen atoms (eg, fluorine, chlorine, bromine, iodine, etc.) ), A nitro group, a cyano group, a mercapto group, an alkoxycarbonyl group (for example, a methyloxycarbonyl group, an ethyloxycarbonyl group, a butyloxycarbonyl group, etc.), or a carboxyl group.

In the general formula (5), R ⁸ represents an oxygen atom, a sulfur atom, NH, SO, SO ₂ , CH ₂ , C (CH ₃ ) ₂ , or C (CF ₃ ) ₂ .

Among the oxetane group-containing compounds represented by the general formula (1-b), in the general formula (1-b), R ^1b represents a lower alkyl group (for example, a methyl group, an ethyl group, a propyl group, etc.). And particularly preferably an ethyl group, and R ^2b is a group in which R ^{7 in the} general formula (4) is a hydrogen atom, a hexamethylene group, R ^{3 in the} general formula (2) is an ethylene group, or a general formula An embodiment in which R ^{5 in} (3) is a methyl group and R ⁴ is a group in which R ^{6 in} general formula (6) is a methyl group, Z is an oxygen atom, and m is 2 is preferable.

  Furthermore, examples of the compound having two or more oxetane groups in the molecule include compounds represented by the following general formula (7) or (8).

In the general formula (7), r represents an integer of 25 to 200, and R ⁹ represents an alkyl group having 1 to 4 carbon atoms or a trialkylsilyl group. In addition, R ¹ in the general formulas (7) and (8) and R ⁶ in the general formula (7) are respectively R ^1b in the general formula (1-b) and R ^{6 in the} general formula (6). It is synonymous with.

  Hereinafter, preferable specific examples [Exemplary compounds 1 to 37 and (a) to (f)] of the oxetane group-containing compound represented by the general formula (1-a) or (1-b) are listed. However, the present invention is not limited to these.

The synthesis of the oxetane group-containing compound is described in (1) HAJ Curless, “Synthetic Organic Photochemistry”, Plenum, New York (1984), (2) M. Braun, Nachr. Chem. Tech. Lab., 33, 213 (1985), (3) SHSchroeter, J. Org. Chem., 34, 5, 1181 (1969), (4) DRArnold, Adv. Photochem., 6, 301 (1968), (5) “Heterocyclic Compounds with Three- and Four-membered Rings ”, Part Two, Chapter IX, Interscience Publishers, John Wiley & Sons, New York (1964), (6) Bull. Chem. Soc. Jpn., 61, 1653 (1988), (7) Pure Appl. Chem., A29 (10), 915 (1992), (8) Pure Appl. Chem., A30 (2 &amp; 3), 189 (1993), (9) JP-A-6-16804, (10) German Patent No. 1,021,858 , Etc. can be referred to.
In addition, the oxetane group-containing compound represented by the general formula (1-b) can also be used in combination of two or more, in addition to being used alone.

  Of the oxetane group-containing compounds, the exemplified compound (a), the exemplified compound (b), the exemplified compound (d), and the exemplified compound (f) are preferable.

<Oxirane group-containing compound>
The oxirane group-containing compound can be appropriately selected from compounds containing at least one oxirane group (oxiranyl group) having the following oxirane ring in the molecule, specifically those usually used as epoxy resins. , Any of monomer, oligomer and polymer.

  Specific examples of the oxirane group-containing compound include conventionally known aromatic epoxy resins, alicyclic epoxy resins, and aliphatic epoxy resins. Here, the epoxy resin refers to a monomer, an oligomer, or a polymer.

  Suitable examples of the aromatic epoxy resin include di- or poly-glycidyl ethers produced by the reaction of a polyhydric phenol having at least one aromatic nucleus or an alkylene oxide adduct thereof and epichlorohydrin. . For example, di- or poly-glycidyl ether of bisphenol A or its alkylene oxide adduct, di- or poly-glycidyl ether of hydrogenated bisphenol A or its alkylene oxide adduct, and novolak type epoxy resin. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

  As the alicyclic epoxy resin, preferably, a compound having at least one cycloalkane ring such as cyclohexene or cyclopentene ring is epoxidized with a suitable oxidizing agent such as hydrogen peroxide or peracid. The cyclohexene oxide or the cyclopentene oxide containing compound obtained by this is mentioned. For example, 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate.

  Suitable examples of the aliphatic epoxy resin include di- or poly-glycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. For example, diglycidyl ether of ethylene glycol, diglycidyl ether of propylene glycol, or diglycidyl ether of alkylene glycol such as diglycidyl ether of 1,6-hexanediol, di- or tri-glycidyl of glycerin or its alkylene oxide adduct Polyglycidyl ether of polyhydric alcohol such as ether, diglycidyl ether of polyethylene glycol or its alkylene oxide adduct, diglycidyl ether of polyalkylene glycol such as polypropylene glycol or diglycidyl ether of its alkylene oxide adduct, and the like. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

As the oxirane group-containing compound, in addition to the above-mentioned compounds, monoglycidyl ethers of aliphatic higher alcohols that are monomers having one oxirane ring in the molecule, monoglycidyl ethers of phenols, cresols or alkylene oxide adducts thereof, etc. Also mentioned.
In addition, the said oxirane group containing compound can also use 2 or more types together besides using individually by 1 type.

  Hereinafter, preferable specific examples (exemplary compounds (i) to (viii)) of the oxirane group-containing compound are listed. However, the present invention is not limited to these.

  Of the oxirane group-containing compounds, the exemplified compound (i) and the exemplified compound (v) are preferable.

  In the present invention, it is preferable that both the oxetane group-containing compound and the oxirane group-containing compound are used in combination. However, as an aspect of the combination, for example, exemplified compound (a) and exemplified compound (i) The aspect which combined and the aspect which combined exemplary compound (b) and exemplary compound (v) are especially preferable at the point which can improve light resistance more effectively.

Examples of the vinyl ether compound include ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, Di- or tri-vinyl ether compounds such as trimethylolpropane trivinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexane dimethanol monovinyl ether Le, n- propyl vinyl ether, isopropyl vinyl ether, isopropenyl ether -O- propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, and octadecyl vinyl ether.
As the vinyl ether compound, a di- or tri-vinyl ether compound is preferable from the viewpoints of curability, adhesion to a recording medium, surface hardness of a formed image, and the like, and a divinyl ether compound is particularly preferable.

  Specific examples of the styrene compound include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropyl styrene, chloromethyl styrene, methoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, bromo styrene, vinyl benzoate. Acid methyl ester, 3-methylstyrene, 4-methylstyrene, 3-ethylstyrene, 4-ethylstyrene, 3-propylstyrene, 4-propylstyrene, 3-butylstyrene, 4-butylstyrene, 3-hexylstyrene, 4 -Hexyl styrene, 3-octyl styrene, 4-octyl styrene, 3- (2-ethylhexyl) styrene, 4- (2-ethylhexyl) styrene, allyl styrene, isopropenyl styrene, butenyl styrene, Tenirusuchiren, 4-t-butoxycarbonyl styrene, 4-methoxystyrene, 4-t-butoxystyrene, and the like.

  When other cation polymerizable compounds are used in combination with the monomer according to the present invention, the other cation polymerizable compounds can be used within a range not impairing the effects of the present invention, but with respect to the total mass of the ink composition, It is preferably 5 to 95% by mass, and more preferably 50 to 95% by mass.

-Photopolymerization initiator-
The ink composition of the present invention can contain at least one photocationic polymerization initiator as a photopolymerization initiator. This cationic photopolymerization initiator refers to a compound that generates an acid upon irradiation with actinic rays or radiation to initiate cationic polymerization, and publicly known compounds and mixtures thereof can be appropriately selected and used.

  As the photocationic polymerization initiator, those listed below may be used alone or in combination of two or more. The content of the present cationic photopolymerization initiator in the ink composition is preferably from 0.1 to 20% by mass, and more preferably from 0.5 to 10% by mass. When the content of the cationic photopolymerization initiator is within the above range, the amount of acid generated can be secured and cured well, and the brittleness of the cured product and the generation of acid due to the remaining initiator will not be a problem. .

  Examples of the photocationic polymerization initiator in the present invention include diazonium salts, phosphonium salts, sulfonium salts, iodonium salts, imide sulfonates, oxime sulfonates, diazodisulfones, disulfones, and o-nitrobenzyl sulfonates.

Further, these photocationic polymerization initiators, or compounds obtained by introducing a group or compound having an equivalent function into the main chain or side chain of the polymer, for example, US Pat. No. 3,849,137, German Patent No. 3914407. JP, 63-26653, JP 55-164824, JP 62-69263, JP 63-146038, JP 63-163452, JP 62-153853, The compounds described in JP-A-63-146029 can be used.
Furthermore, compounds capable of generating an acid by light described in US Pat. No. 3,779,778, European Patent 126,712 and the like can also be used.

  Preferred examples of the photoacid generator that can be used in the present invention include compounds represented by the following general formulas (b1), (b2), and (b3).

In the general formula (b1), R ²⁰¹ , R ²⁰² and R ²⁰³ each independently represents an organic group.
X ⁻ represents a non-nucleophilic anion, preferably a sulfonate anion, a carboxylate anion, a bis (alkylsulfonyl) amide anion, a tris (alkylsulfonyl) methide anion, BF ₄ ⁻ , PF ₆ ⁻ , SbF ₆ ⁻ or the following The organic anion which has a carbon atom is preferable.

Preferable organic anions include organic anions represented by the following formula.

Rc ¹ represents an organic group. Examples of the organic group in Rc ¹ include those having ^{1 to} 30 carbon atoms, and preferably an alkyl group, a cycloalkyl group, an aryl group, or a plurality of these are a single bond, —O—, —CO ₂ —, —S—. , —SO ₃ —, —SO ₂ N (Rd ¹ ) — and the like.

Rd ¹ represents a hydrogen atom or an alkyl group. Rc ³ , Rc ⁴ and Rc ⁵ each independently represents an organic group. Preferred examples of the organic group for Rc ³ , Rc ⁴ , and Rc ⁵ include the same organic groups as those for Rc ¹ , and most preferably a perfluoroalkyl group having 1 to 4 carbon atoms. Rc ³ and Rc ⁴ may combine to form a ring. Examples of the group formed by combining Rc ³ and Rc ⁴ include an alkylene group and an arylene group. A perfluoroalkylene group having 2 to 4 carbon atoms is preferred.

The organic group represented by Rc ^1, Rc ³ to Rc ^5, most preferably 1-position fluorine atom or an alkyl group substituted with a fluoroalkyl group, a phenyl group substituted with a fluorine atom or a fluoroalkyl group. By having a fluorine atom or a fluoroalkyl group, the acidity of the acid generated by light irradiation is increased and the sensitivity is improved.

The carbon number of the organic group as R ²⁰¹ , R ²⁰² and R ²⁰³ is generally 1-30, preferably 1-20.
Two of R ^{201 to} R ²⁰³ may be bonded to form a ring structure, and the ring may contain an oxygen atom, a sulfur atom, an ester bond, an amide bond, or a carbonyl group. The two of the group formed by bonding of the R ²⁰¹ to R ^203, there can be mentioned an alkylene group (e.g., butylene, pentylene).

Specific examples of the organic group as R ²⁰¹ , R ²⁰² and R ²⁰³ include corresponding groups in the compounds (b1-1), (b1-2) and (b1-3) described later.
In addition, the compound which has two or more structures represented by general formula (b1) may be sufficient. For example, at least one of R ²⁰¹ to R ²⁰³ of the compound represented by the general formula (b1) is at least one directly with R ²⁰¹ to R ²⁰³ of another compound represented by formula (b1), or, It may be a compound having a structure bonded through a linking group.

  More preferred components (b1) include compounds (b1-1), (b1-2), and (b1-3) described below.

Compound (b1-1) is at least one R ²⁰¹ to R ²⁰³ of Formula (b1) is an aryl group, an arylsulfonium compound, i.e., a compound having arylsulfonium as a cation.

In the arylsulfonium compound, all of R ^{201 to} R ²⁰³ may be an aryl group, or a part of R ^{201 to} R ²⁰³ may be an aryl group, and the rest may be an alkyl group or a cycloalkyl group.

  Examples of the arylsulfonium compound include triarylsulfonium compounds, diarylalkylsulfonium compounds, aryldialkylsulfonium compounds, diarylcycloalkylsulfonium compounds, aryldicycloalkylsulfonium compounds, and the like.

  The aryl group of the arylsulfonium compound is preferably an aryl group such as a phenyl group or a naphthyl group, or a heteroaryl group such as an indole residue or a pyrrole residue, more preferably a phenyl group or an indole residue. When the arylsulfonium compound has two or more aryl groups, the two or more aryl groups may be the same or different.

As the alkyl group that the arylsulfonium compound has as necessary, a linear or branched alkyl group having 1 to 15 carbon atoms is preferable. For example, a methyl group, an ethyl group, a propyl group, an n-butyl group, sec -A butyl group, a t-butyl group, etc. can be mentioned.
The cycloalkyl group that the arylsulfonium compound has as necessary is preferably a cycloalkyl group having 3 to 15 carbon atoms, and examples thereof include a cyclopropyl group, a cyclobutyl group, and a cyclohexyl group.

The aryl group, alkyl group, and cycloalkyl group of R ^{201 to} R ²⁰³ are an alkyl group (for example, having 1 to 15 carbon atoms), a cycloalkyl group (for example, having 3 to 15 carbon atoms), an aryl group (for example, having 6 to 14 carbon atoms). ), An alkoxy group (for example, having 1 to 15 carbon atoms), a halogen atom, a hydroxyl group, or a phenylthio group as a substituent. Preferable substituents are a linear or branched alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, and a linear, branched or cyclic alkoxy group having 1 to 12 carbon atoms, and most preferable. Is an alkyl group having 1 to 4 carbon atoms and an alkoxy group having 1 to 4 carbon atoms. The substituent may be substituted with any one of the three R ^{201 to} R ²⁰³ , or may be substituted with all three. When R ^{201 to} R ²⁰³ are an aryl group, the substituent is preferably substituted at the p-position of the aryl group.

Next, the compound (b1-2) will be described.
The compound (b1-2) is a compound in the case where R ^{201 to} R ²⁰³ in the formula (b1) each independently represents an organic group not containing an aromatic ring. Here, the aromatic ring includes an aromatic ring containing a hetero atom.
The organic group having no aromatic ring as R ²⁰¹ to R ²⁰³ generally has 1 to 30 carbon atoms, preferably 1 to 20 carbon atoms.
R ^{201 to} R ²⁰³ are each independently preferably an alkyl group, a cycloalkyl group, an allyl group or a vinyl group, more preferably a linear, branched or cyclic 2-oxoalkyl group, an alkoxycarbonylmethyl group, particularly A linear or branched 2-oxoalkyl group is preferred.

The alkyl group as R ²⁰¹ to R ²⁰³ may be linear, may be either branched, preferably a straight-chain or branched alkyl group (e.g., methyl group having 1 to 10 carbon atoms, an ethyl group, a propyl Group, a butyl group, a pentyl group), and a linear, branched 2-oxoalkyl group, and an alkoxycarbonylmethyl group are more preferable.

The cycloalkyl group as R ²⁰¹ to R ²⁰³ is preferably a cycloalkyl group having 3 to 10 carbon atoms (a cyclopentyl group, a cyclohexyl group, a norbornyl group) can be exemplified, more preferably a cyclic 2-oxoalkyl group.

Preferred examples of the linear, branched or cyclic 2-oxoalkyl group represented by R ^{201 to} R ²⁰³ include a group having> C═O at the 2-position of the alkyl group or cycloalkyl group.
The alkoxy group in the alkoxycarbonylmethyl group as R ²⁰¹ to R ^203, preferably may be mentioned alkoxy groups having 1 to 5 carbon atoms (a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a pentoxy group).
R ^{201 to} R ²⁰³ may be further substituted with a halogen atom, an alkoxy group (eg, having 1 to 5 carbon atoms), a hydroxyl group, a cyano group, or a nitro group.

  The compound (b1-3) is a compound represented by the following general formula (b1-3), and is a compound having a phenacylsulfonium salt structure.

In General Formula (b1-3), R ^{1c to} R ^5c each independently represent a hydrogen atom, an alkyl group, a cycloalkyl group, an alkoxy group, or a halogen atom.
R ^6c and R ^7c each independently represents a hydrogen atom, an alkyl group or a cycloalkyl group.
R ^x and R ^y each independently represents an alkyl group, a cycloalkyl group, an allyl group, or a vinyl group.
Any two or more of R ^{1c to} R ^5c , R ^6c and R ^7c , and R ^x and R ^y may be bonded to each other to form a ring structure.
Zc ⁻ represents a non-nucleophilic anion, and examples thereof include the same as the non-nucleophilic anion of X ⁻ in formula (b1).

The alkyl group as R ^{1c to} R ^7c may be either linear or branched, and for example, a linear or branched alkyl group having 1 to 20 carbon atoms, preferably 1 to 12 carbon atoms (for example, methyl Group, ethyl group, linear or branched propyl group, linear or branched butyl group, linear or branched pentyl group).

Preferred examples of the cycloalkyl group represented by R ^{1c to} R ^7c include cycloalkyl groups having 3 to 8 carbon atoms (for example, a cyclopentyl group and a cyclohexyl group).

The alkoxy group as R ^{1c to} R ^{5c may} be linear, branched or cyclic, for example, an alkoxy group having 1 to 10 carbon atoms, preferably a linear or branched alkoxy group having 1 to 5 carbon atoms. (For example, methoxy group, ethoxy group, linear or branched propoxy group, linear or branched butoxy group, linear or branched pentoxy group), cyclic alkoxy group having 3 to 8 carbon atoms (for example, cyclopentyloxy group, cyclohexyloxy group) ).

Examples of the group formed by combining any two or more of R ^{1c to} R ^5c , R ^6c and R ^7c , and R ^x and R ^y include a butylene group and a pentylene group. This ring structure may contain an oxygen atom, a sulfur atom, an ester bond, or an amide bond.

Preferably any one of R ^{1c to} R ^5c is a linear or branched alkyl group, a cycloalkyl group, or a linear, branched or cyclic alkoxy group, and more preferably the sum of the carbon number of R ^1c to R ^5c is 2-15. Thereby, solvent solubility improves more and generation | occurrence | production of a particle is suppressed at the time of a preservation | save.

^Examples of the alkyl group and cycloalkyl group as R ^x and R ^y include the same alkyl groups and cycloalkyl groups as R ^{1c to} R ^7c . R ^x and R ^y are preferably a 2-oxoalkyl group or an alkoxycarbonylmethyl group. Examples of the 2-oxoalkyl group include a group having> C═O at the 2-position of the alkyl group or cycloalkyl group as R ^{1c to} R ^5c . Examples of the alkoxy group in the alkoxycarbonylmethyl group include the same alkoxy groups as R ^{1c to} R ^5c .

R ^x and R ^y are preferably an alkyl group or cycloalkyl group having 4 or more carbon atoms, more preferably 6 or more, and still more preferably 8 or more.

In the formula (b2), (b3), R 204 ~R 207 each independently represents an aryl group, an alkyl group or a cycloalkyl group. X ⁻ represents a non-nucleophilic anion, and examples thereof include the same as the non-nucleophilic anion of X ⁻ in formula (b1).

Phenyl group and a naphthyl group are preferred as the aryl group of R ²⁰⁴ to R ^207, more preferably a phenyl group.
The alkyl group as R ^{204 to} R ²⁰⁷ may be either linear or branched, and is preferably a linear or branched alkyl group having 1 to 10 carbon atoms (for example, methyl group, ethyl group, propyl group). Group, butyl group, pentyl group). The cycloalkyl group as R ²⁰⁴ to R ²⁰⁷ is preferably, and a cycloalkyl group having 3 to 10 carbon atoms (e.g., cyclopentyl, cyclohexyl, norbornyl).
The R ²⁰⁴ to R ²⁰⁷ are substituents which may have, for example, an alkyl group (for example, 1 to 15 carbon atoms), a cycloalkyl group (for example, 3 to 15 carbon atoms), an aryl group (e.g., 6 carbon atoms 15), alkoxy groups (for example, having 1 to 15 carbon atoms), halogen atoms, hydroxyl groups, phenylthio groups and the like.

  Examples of the photocationic polymerization initiator that may be used further include compounds represented by the following general formulas (b4), (b5), and (b6).

In general formulas (b4) to (b6), Ar ³ and Ar ⁴ each independently represents an aryl group.
R ²⁰⁶ , R ²⁰⁷ and R ²⁰⁸ each independently represents an alkyl group, a cycloalkyl group or an aryl group.
A represents an alkylene group, an alkenylene group or an arylene group.

Preferable examples of the cationic photopolymerization initiator include compounds represented by general formulas (b1) to (b3).
Examples of particularly preferred photocationic polymerization initiators that can be used in the present invention are listed below.

  Further, oxazole derivatives and s-triazine derivatives described in JP-A No. 2002-122994, paragraph numbers [0029] to [0030] are also preferably used. The onium salt compounds and sulfonate compounds exemplified in JP-A No. 2002-122994, paragraph numbers [0037] to [0063] can also be suitably used in the present invention.

As the active energy ray irradiated for proceeding the polymerization of the ink composition of the present invention, α ray, γ ray, X ray, ultraviolet ray, visible ray, electron beam and the like can be used. Of these, ultraviolet rays and visible rays are preferably used from the viewpoint of cost and safety, and ultraviolet rays are more preferably used.
As a light source for generating ultraviolet rays, low-pressure mercury lamps, high-pressure mercury lamps, short arc discharge lamps, ultraviolet light-emitting diodes, and the like, which are known ultraviolet lamps, can be used. High pressure mercury lamps, metal halide lamps, and xenon lamps belonging to short arc discharge lamps are preferably used. Moreover, an ultraviolet light emitting diode is also preferably used from the viewpoint of energy saving.

(Surfactant)
The ink composition of the present invention preferably contains a surfactant.
Examples of the surfactant include those described in JP-A Nos. 62-173463 and 62-183457. Specifically, for example, anionic surfactants such as dialkyl sulfosuccinates, alkyl naphthalene sulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene -Nonionic surfactants such as polyoxypropylene block copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. An organic fluoro compound may be used instead of the known surfactant. The organic fluoro compound is preferably hydrophobic. Examples of the organic fluoro compounds include fluorine surfactants, oily fluorine compounds (eg, fluorine oil) and solid fluorine compound resins (eg, tetrafluoroethylene resin). No. (columns 8 to 17) and those described in JP-A Nos. 62-135826.

  As content of surfactant in this invention, 0.001-0.6 mass% is preferable with respect to the said polymeric compound, Furthermore, 0.003-0.3 mass% is preferable, 0.01-0. 1% by mass is particularly preferred.

(Coloring agent)
The ink composition of the present invention can form a visible image by adding a colorant. The colorant that can be used in the ink composition of the present invention is not particularly limited, and various known color materials (pigments, dyes) can be appropriately selected and used depending on the application. For example, when forming an image excellent in weather resistance, a pigment is preferable. As the dye, both water-soluble dyes and oil-soluble dyes can be used, but oil-soluble dyes are preferred.

<Pigment>
First, a pigment that is preferably used as a colorant in the present invention will be described.
The pigment is not particularly limited, and all commercially available organic pigments and inorganic pigments or pigments dispersed in an insoluble resin or the like as a dispersion medium, or a resin is grafted on the pigment surface. Can be used. Moreover, what dye | stained the resin particle with dye can be used.
Examples of these pigments include, for example, “Pigment Dictionary” (2000), edited by Seijiro Ito. Herbst, K.M. Hunger “Industrial Organic Pigments”, JP 2002-12607 A, JP 2002-188025 A, JP 2003-26978 A, and JP 2003-342503 A3.

  Specific examples of organic pigments and inorganic pigments that can be used in the present invention include, for example, C.I. I. Pigment Yellow 1 (Fast Yellow G etc.), C.I. I. A monoazo pigment such as C.I. Pigment Yellow 74; I. Pigment Yellow 12 (disaji yellow AAA, etc.), C.I. I. Disazo pigments such as C.I. Pigment Yellow 17; I. Non-benzidine type azo pigments such as CI Pigment Yellow 180; I. Azo lake pigments such as C.I. Pigment Yellow 100 (eg Tartrazine Yellow Lake); I. Pigment yellow 128, pigment yellow 93, C.I. I. Condensed azo pigments such as CI Pigment Yellow 95 (Condensed Azo Yellow GR, etc.); I. Acidic dye lake pigments such as C.I. Pigment Yellow 115 (such as quinoline yellow lake); I. Basic dye lake pigments such as CI Pigment Yellow 18 (Thioflavin Lake, etc.), anthraquinone pigments such as Flavantron Yellow (Y-24), isoindolinone pigments such as Isoindolinone Yellow 3RLT (Y-110), and quinophthalone yellow Quinophthalone pigments such as (Y-138), isoindoline pigments such as isoindoline yellow (Y-139), C.I. I. Nitroso pigments such as C.I. Pigment Yellow 153 (nickel nitroso yellow, etc.); I. And metal complex salt azomethine pigments such as CI Pigment Yellow 117 (copper azomethine yellow, etc.).

  Examples of red or magenta colors include C.I. I. Monoazo pigments such as CI Pigment Red 3 (Toluidine Red, etc.); I. Disazo pigments such as C.I. Pigment Red 38 (Pyrazolone Red B, etc.); I. Pigment Red 53: 1 (Lake Red C, etc.) and C.I. I. Azo lake pigments such as C.I. Pigment Red 57: 1 (Brilliant Carmine 6B); I. Condensed azo pigments such as C.I. Pigment Red 144 (condensed azo red BR, etc.); I. Acidic dye lake pigments such as C.I. Pigment Red 174 (Phloxine B Lake, etc.); I. Basic dye lake pigments such as C.I. Pigment Red 81 (Rhodamine 6G ′ Lake, etc.); I. Anthraquinone pigments such as C.I. Pigment Red 177 (eg, dianthraquinonyl red); I. Thioindigo pigments such as C.I. Pigment Red 88 (Thioindigo Bordeaux, etc.); I. Perinone pigments such as C.I. Pigment Red 194 (perinone red, etc.); I. Perylene pigments such as C.I. Pigment Red 149 (perylene scarlet, etc.); I. Pigment violet 19 (unsubstituted quinacridone), C.I. I. Quinacridone pigments such as CI Pigment Red 122 (quinacridone magenta, etc.); I. Isoindolinone pigments such as CI Pigment Red 180 (isoindolinone red 2BLT, etc.); I. And alizarin lake pigments such as CI Pigment Red 83 (Mada Lake, etc.).

  Examples of pigments exhibiting blue or cyan colors include C.I. I. Disazo pigments such as C.I. Pigment Blue 25 (Dianisidine Blue, etc.); I. Phthalocyanine pigments such as C.I. Pigment Blue 15 (phthalocyanine blue, etc.); I. Acidic dye lake pigments such as C.I. Pigment Blue 24 (Peacock Blue Lake, etc.); I. Basic dye lake pigments such as C.I. Pigment Blue 1 (Viclotia Pure Blue BO Lake, etc.); I. Anthraquinone pigments such as C.I. Pigment Blue 60 (Indantron Blue, etc.); I. And alkali blue pigments such as CI Pigment Blue 18 (Alkali Blue V-5: 1).

Examples of green pigments include C.I. I. Pigment green 7 (phthalocyanine green), C.I. I. Phthalocyanine pigments such as C.I. Pigment Green 36 (phthalocyanine green); I. And azo metal complex pigments such as CI Pigment Green 8 (Nitroso Green).
Examples of the orange pigment include C.I. I. An isoindoline pigment such as C.I. Pigment Orange 66 (isoindoline orange); I. And anthraquinone pigments such as CI Pigment Orange 51 (dichloropyrantron orange).

Examples of black pigments include carbon black, titanium black, and aniline black.
Specific examples of the white pigment include basic lead carbonate (2PbCO ₃ Pb (OH) ₂ , so-called silver white), zinc oxide (ZnO, so-called zinc white), titanium oxide (TiO ₂ , so-called titanium white), Strontium titanate (SrTiO ₃ , so-called titanium strontium white) or the like can be used.

  Here, titanium oxide has a smaller specific gravity than other white pigments, a large refractive index, and is chemically and physically stable, so that it has a large hiding power and coloring power as a pigment. Excellent durability against other environments. Therefore, it is preferable to use titanium oxide as the white pigment. Of course, other white pigments (may be other than the listed white pigments) may be used as necessary.

For dispersion of the pigment, for example, a dispersion device such as a ball mill, a sand mill, an attritor, a roll mill, a jet mill, a homogenizer, a paint shaker, a kneader, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, or a wet jet mill is used. Can do.
It is also possible to add a dispersant when dispersing the pigment. Examples of the dispersant include a hydroxyl group-containing carboxylic acid ester, a salt of a long-chain polyaminoamide and a high molecular weight acid ester, a salt of a high molecular weight polycarboxylic acid, a high molecular weight unsaturated acid ester, a high molecular weight copolymer, a modified polyacrylate, an aliphatic polyacrylate. Carboxylic acid, naphthalenesulfonic acid formalin condensate, polyoxyethylene alkyl phosphate ester, pigment derivative and the like. It is also preferable to use a commercially available polymer dispersant such as the Solsperse series from Zeneca.
Moreover, it is also possible to use a synergist according to various pigments as a dispersion aid. These dispersants and dispersion aids are preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the pigment.

  In the ink composition, as a dispersion medium for various components such as pigments, a solvent may be added, and the polymerizable compound which is a low molecular weight component without a solvent may be used as a dispersion medium. The ink composition of the invention is a radiation curable ink, and is preferably solvent-free in order to be cured after the ink is applied to a recording medium. This is because if the solvent remains in the cured ink image, the solvent resistance is deteriorated or a VOC (Volatile Organic Compound) problem of the remaining solvent occurs. From such a viewpoint, a polymerizable compound is used as the dispersion medium, and among them, it is preferable to select a cationically polymerizable monomer having the lowest viscosity from the viewpoint of improving dispersibility and handling properties of the ink composition.

  The average particle size of the pigment particles is preferably 0.08 to 0.5 μm, and the maximum particle size is preferably 10 μm or less, more preferably 3 μm or less, selection of pigment, dispersant, dispersion medium, dispersion Set the conditions and filtration conditions. By controlling the particle size, clogging of the head nozzle can be suppressed, and ink storage stability, ink transparency, and curing sensitivity can be maintained.

<Dye>
Next, the dyes preferably used as the colorant in the present invention will be described.
The dye can be appropriately selected from conventionally known compounds (dyes). Specific examples include dyes described in paragraphs [0023] to [0089] of JP-A No. 2002-114930.

  Yellow dyes include, for example, phenols, naphthols, anilines, pyrazolones, pyridones, aryl or heteryl azo dyes having open-chain active methylene compounds as coupling components, for example open-chain active methylene compounds as coupling components Azomethine dyes having, for example, methine dyes such as benzylidene dyes and monomethine oxonol dyes, for example, quinone dyes such as naphthoquinone dyes and anthraquinone dyes, and other dyes include quinophthalone dyes and nitro dyes Nitroso dyes, acridine dyes, acridinone dyes and the like.

  Examples of the magenta dye include phenols, naphthols, anilines, pyrazolones, pyridones, pyrazolotriazoles, and ring-closing active methylene compounds (for example, dimedone, barbituric acid, 4-hydroxycoumarin) as coupling components. Derivatives), electron-rich heterocycles (eg, pyrrole, imidazole, thiophene, thiazole derivatives), or aryl or heteryl azo dyes, eg, azomethine dyes having pyrazolones, pyrazolotriazoles as coupling components, eg, arylidene dyes, styryl Dyes, merocyanine dyes, methine dyes such as oxonol dyes, carbonium dyes such as diphenylmethane dyes, triphenylmethane dyes, xanthene dyes, such as naphthoquinone, anthraquinone, anthrone Quinone dyes such Rapiridon, it can be mentioned condensed polycyclic dyes such as, for example, dioxazine dye.

  Examples of the cyan dye include azomethine dyes such as indoaniline dyes and indophenol dyes, cyanine dyes, oxonol dyes, polymethine dyes such as merocyanine dyes, carbonium dyes such as diphenylmethane dyes, triphenylmethane dyes, and xanthene dyes; Examples of phthalocyanine dyes and anthraquinone dyes include phenols, naphthols, anilines, pyrrolopyrimidin-one, aryl or heteryl azo dyes having pyrrolotriazin-one derivatives, and indigo / thioindigo dyes as coupling components.

  Each of the above dyes may exhibit yellow, magenta, and cyan colors only after part of the chromophore is dissociated, and the counter cation in this case is an inorganic cation such as an alkali metal or ammonium. Alternatively, it may be an organic cation such as pyridinium, quaternary ammonium salt, or a cationic polymer having a partial structure thereof.

  The dye that can be used in the present invention is preferably oil-soluble. “Oil-soluble” specifically means that the solubility in water at 25 ° C. (the mass of the dye dissolved in 100 g of water) is 1 g or less, preferably 0.5 g or less, more preferably 0. .1 g or less. Therefore, a so-called water-insoluble oil-soluble dye is preferably used.

The dye used in the present invention preferably has an oil-solubilizing group introduced into the above-described dye matrix in order to dissolve the necessary amount in the ink composition.
Examples of the oil-solubilizing group include a long chain, branched alkyl group, long chain, branched alkoxy group, long chain, branched alkylthio group, long chain, branched alkylsulfonyl group, long chain, branched acyloxy group, long chain, branched alkoxycarbonyl group. , Long chain, branched acyl group, long chain, branched acylamino group long chain, branched alkylsulfonylamino group, long chain, branched alkylaminosulfonyl group, and these long chains, aryl groups including branched substituents, aryloxy groups, aryloxy Examples include a carbonyl group, an arylcarbonyloxy group, an arylaminocarbonyl group, an arylaminosulfonyl group, an arylsulfonylamino group.
In addition, for water-soluble dyes having carboxylic acid and sulfonic acid, long chain, branched alcohol, amine, phenol, aniline derivatives are used as oil-solubilizing alkoxycarbonyl groups, aryloxycarbonyl groups, alkylaminosulfonyl groups, A dye may be obtained by conversion to an arylaminosulfonyl group.

The oil-soluble dye preferably has a melting point of 200 ° C. or lower, more preferably has a melting point of 150 ° C. or lower, and still more preferably has a melting point of 100 ° C. or lower. By using an oil-soluble dye having a low melting point, the precipitation of dye crystals in the ink composition is suppressed, and the storage stability of the ink composition is improved.
Further, it is desirable that the oxidation potential is noble (high) in order to improve fading, particularly resistance to oxidizing substances such as ozone and curing characteristics. For this reason, as the oil-soluble dye used in the present invention, those having an oxidation potential of 1.0 V (vs SCE) or more (preferably higher than 1.0 V (vs SCE)) are preferably used. The oxidation potential is preferably higher, the oxidation potential is more preferably 1.1 V (vs SCE) or more, and particularly preferably 1.15 V (vs SCE) or more.

As the yellow dye, a compound having a structure represented by the general formula (Y-I) described in JP-A No. 2004-250483 is preferable.
Particularly preferred dyes are dyes represented by general formulas (Y-II) to (Y-IV) described in paragraph [0034] of JP-A No. 2004-250483. And the compounds described in paragraph numbers [0060] to [0071] of JP-A-250483. The oil-soluble dye of the general formula (Y-I) described in the publication may be used not only for yellow but also for inks of any color such as black ink and red ink.

The magenta dye is preferably a compound having a structure represented by the general formulas (3) and (4) described in JP-A No. 2002-114930. Specific examples include paragraphs of JP-A No. 2002-114930. Examples include the compounds described in [0054] to [0073].
Particularly preferred dyes are azo dyes represented by the general formulas (M-1) to (M-2) described in paragraph numbers [0084] to [0122] of JP-A No. 2002-121414, and specific examples Examples thereof include compounds described in paragraph numbers [0123] to [0132] of JP-A No. 2002-121414. The oil-soluble dyes represented by the general formulas (3), (4) and (M-1) to (M-2) described in the publication are used not only for magenta but also for any color ink such as black ink and red ink. May be.

Examples of the cyan dye include dyes represented by formulas (I) to (IV) described in JP-A No. 2001-181547, and paragraphs [0063] to [0078] of JP-A No. 2002-121414. The dyes represented by the general formulas (IV-1) to (IV-4) described above are preferred, and specific examples include paragraph numbers [0052] to [0066] of JP-A No. 2001-181547. Examples thereof include the compounds described in paragraph Nos. [0079] to [0081] of Kai 2002-121414.
Particularly preferred dyes are phthalocyanine dyes represented by general formulas (CI) and (C-II) described in paragraphs [0133] to [0196] of JP-A No. 2002-121414, A phthalocyanine dye represented by formula (C-II) is preferred. Specific examples thereof include the compounds described in JP-A No. 2002-121414, paragraph numbers [0198] to [0201]. The oil-soluble dyes of the formulas (I) to (IV), (IV-1) to (IV-4), (CI), and (C-II) are not only cyan but also black ink or green ink. The ink may be used for any color ink.

-Oxidation potential-
The oxidation potential value (Eox) of the dye in the present invention can be easily measured by those skilled in the art. Regarding this method, for example "New Instrumental Methods in Electrochemistry" by Delahay (1954, published by Interscience Publishers) J. et al. It is described in Bard et al. "Electrochemical Methods" (1980, published by John Wiley & Sons), Fujishima Akira et al. "Electrochemical measurement method" (1984, published by Gihodo Publishing Co., Ltd.).
Specifically, the oxidation potential is 1 × 10 ⁻² to 1 × 10 ⁻⁶ mol / min in a solvent such as dimethylformamide or acetonitrile containing a supporting electrolyte such as sodium perchlorate or tetrapropylammonium perchlorate. Using a voltammetry device, approximate the oxidation wave with a straight line by using a voltammetry device to sweep carbon (GC) as the working electrode and the rotating platinum electrode as the counter electrode to the oxidation side (noble side). SCE (saturated calomel electrode) is the intermediate potential value of the line segment formed by the intersection of the current / potential line and the intersection of the straight line and the saturation current line (or the intersection of the straight line parallel to the vertical axis passing through the peak potential value). ) As a value for. Although this value may be deviated by several tens of mil volts due to the influence of the liquid potential difference or the liquid resistance of the sample solution, the reproducibility of the potential can be guaranteed by inserting a standard sample (for example, hydroquinone). The supporting electrolyte and solvent to be used can be selected appropriately depending on the oxidation potential and solubility of the test sample. The supporting electrolyte and the solvent that can be used are described in pages 101 to 118 of Akira Fujishima et al., “Electrochemical measurement method” (published by Gihodo Publishing Co., 1984).
In the concentration range of the measurement solvent and the phthalocyanine compound sample, the oxidation potential in a non-association state is measured.
The value of Eox represents the ease of electron transfer from the sample to the electrode, and the greater the value (the higher the oxidation potential), the more difficult the electron transfer from the sample to the electrode, in other words, the less easily oxidized.
Specific examples of preferable dyes used in the present invention are shown below, but the dyes used in the present invention are not limited to the following specific examples.

  The colorant is preferably added in an amount of 0.05 to 20% by mass, more preferably 0.2 to 10% by mass, based on the total mass of the ink composition. Moreover, when an oil-soluble dye is used as a colorant, 0.2 to 6% by mass is particularly preferable.

(Additive)
In addition to the essential components, various additives can be used in combination with the ink composition of the present invention depending on the purpose. These optional components will be described.

-Sensitizing dye-
In the present invention, a sensitizing dye can be added for the purpose of improving the sensitivity of the photopolymerization initiator. Hereinafter, the sensitizing dye will be described.

  Examples of the sensitizing dye according to the present invention include those belonging to the compounds listed below and having an absorption wavelength in a wavelength region of 350 nm to 450 nm.

  For example, polynuclear aromatics (eg, pyrene, perylene, triphenylene, 2-ethyl-9,10-dimethoxyanthracene, etc.), xanthenes (eg, fluorescein, eosin, erythrosine, rhodamine B, rose bengal, etc.) , Cyanines (eg, thiacarbocyanine, oxacarbocyanine, etc.), merocyanines (eg, merocyanine, carbomerocyani, etc.), thiazines (eg, thionine, methylene blue, toluidine blue, etc.), acridines (eg, Acridine orange, chloroflavin, acriflavine, etc.), anthraquinones (eg, anthraquinone, etc.), squaliums (eg, squalium, etc.), coumarins (eg, 7-diethylamino-4-methylcoumarin, etc.), etc. Mentioned That.

Preferred examples of the sensitizing dye in the invention include compounds represented by the following general formulas (vi) to (x).

In the general formula (vi), A ¹ represents a sulfur atom or NR ^50, R ⁵⁰ represents an alkyl group or an aryl group. L ¹ represents a nonmetallic atomic group that forms a basic nucleus of the dye in cooperation with the adjacent A ¹ and the adjacent carbon atom. R ⁵¹ and R ⁵² each independently represent a hydrogen atom or a monovalent nonmetallic atomic group, and R ⁵¹ and R ⁵² may be bonded to each other to form an acidic nucleus of the dye. W represents an oxygen atom or a sulfur atom.

In general formula (vii), Ar ¹ and Ar ² each independently represent an aryl group and are linked via a bond with L ² . L ² represents —O— or S—. W is synonymous with that shown in the general formula (vi).

In general formula (viii), A ² represents a sulfur atom or NR ⁵⁹ , and R ⁵⁹ represents an alkyl group or an aryl group. L ³ represents a nonmetallic atomic group that forms a basic nucleus of a dye in cooperation with adjacent A ² and a carbon atom. R ⁵³ , R ⁵⁴ , R ⁵⁵ , R ⁵⁶ , R ⁵⁷ and R ⁵⁸ each independently represents a monovalent nonmetallic atomic group.

In general formula (ix), A ³ and A ⁴ each independently represent —S—, —NR ⁶² —, or NR ⁶³ —, and R ⁶² and R ⁶³ each independently represent a substituted or unsubstituted group. An alkyl group or a substituted or unsubstituted aryl group is represented. L ⁴ and L ⁵ each independently represents a nonmetallic atomic group that forms a basic nucleus of a dye in cooperation with adjacent A ³ , A ⁴ and adjacent carbon atoms. R ⁶⁰ and R ⁶¹ each independently represent a hydrogen atom or a monovalent nonmetallic atomic group. R ⁶⁰ and R ⁶¹ may be bonded to each other to form an aliphatic or aromatic ring.

In general formula (x), R ⁶⁶ represents an aromatic ring or a heterocyclic ring which may have a substituent. A ⁵ represents an oxygen atom, a sulfur atom or NR ⁶⁷ —. R ⁶⁴ , R ⁶⁵ and R ⁶⁷ each independently represent a hydrogen atom or a monovalent nonmetallic atomic group. R ⁶⁷ and R ⁶⁴ , and R ⁶⁵ and R ⁶⁷ may be bonded to each other to form an aliphatic or aromatic ring.

  Preferred specific examples of the compounds represented by the general formulas (vi) to (x) include, but are not limited to, those shown below.

The content of the sensitizing dye in the ink composition of the present invention is preferably 0.01 to 20% by mass with respect to the total amount (total mass) of the ink composition, from the viewpoint of colorability of the ink. -15 mass% is more preferable, More preferably, it is the range of 0.5-10 mass%.
The said sensitizing dye may be used individually by 1 type, and may use 2 or more types together.
The content ratio of the sensitizing dye and the photopolymerization initiator in the ink composition is a mass ratio of a / c from the viewpoint of improving the decomposition rate of the photopolymerization initiator and transmitting light. = 100-0.5 is preferable, a / c = 50-1 is more preferable, and a / c = 10-1.5 is still more preferable.

-Co-sensitizer-
The ink composition of the present invention may further contain a known compound having a function of further improving sensitivity or suppressing inhibition of polymerization by oxygen as a cosensitizer.

  Examples of co-sensitizers include amines such as M.I. R. Sander et al., “Journal of Polymer Society”, Vol. 10, 3173 (1972), Japanese Patent Publication No. 44-20189, Japanese Patent Publication No. 51-82102, Japanese Patent Publication No. 52-134692, Japanese Patent Publication No. 59-138205. No. 60-84305, JP-A 62-18537, JP-A 64-33104, Research Disclosure 33825, and the like. Specific examples include triethanolamine. P-dimethylaminobenzoic acid ethyl ester, p-formyldimethylaniline, p-methylthiodimethylaniline and the like.

  Other examples of co-sensitizers include thiols and sulfides such as thiol compounds described in JP-A-53-702, JP-B-55-500806, and JP-A-5-142277, No. 56-75643, such as 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-mercaptobenzimidazole, 2-mercapto-4 (3H) -quinazoline, β-mercapto. And naphthalene.

Other examples of the co-sensitizer include amino acid compounds (eg, N-phenylglycine), organometallic compounds described in JP-B-48-42965 (eg, tributyltin acetate), JP-B 55- No. 34414, a hydrogen donor described in JP-A-6-308727 (eg, trithiane), a phosphorus compound described in JP-A-6-250387 (eg diethylphosphite), Examples include Si-H and Ge-H compounds described in 191605.
The addition amount is appropriately selected according to the purpose, but is generally about 0.01 to 10% by mass with respect to the total amount (total mass) of the ink composition.

-Polymerization inhibitor-
The ink composition of the present invention can contain at least one polymerization inhibitor.
Examples of the polymerization inhibitor include phenolic hydroxyl group-containing compounds, quinones, N-oxide compounds, piperidine-1-oxyl free radical compounds, pyrrolidine-1-oxyl free radical compounds, and N-nitrosophenylhydroxylamines. And a compound selected from the group consisting of cationic dyes.

  Specifically, haloquinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, resorcinol, catechol, t-butylcatechol, hydroquinone monoalkyl ether (for example, hydroquinone monomethyl ether, hydroquinone monobutyl ether), Benzoquinone, 4,4-thiobis (3-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2,6,6-tetramethylpiperidine and its Derivatives, di-t-butyl nitroxide, 2,2,6,6-tetramethylpiperidine-N-oxide and derivatives thereof, piperidine 1-oxyl free radical, 2,2,6,6-tetramethylpiperidine 1-oxyl Free radicals, 4- Oxo-2,2,6,6-tetramethylpiperidine 1-oxyl free radical, 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl free radical, 4-acetamido-2,2,6 6-tetramethylpiperidine 1-oxyl free radical, 4-maleimido-2,2,6,6-tetramethylpiperidine 1-oxyl free radical, 4-phosphonoxy-2,2,6,6-tetramethylpiperidine 1-oxyl Free radical, 3-carboxy-2,2,5,5-tetramethylpyrrolidine 1-oxyl free radical, N-nitrosophenylhydroxylamine cerium salt, N-nitrosophenylhydroxylamine aluminum salt, crystal violet, methyl violet, Ethyl violet , And Victoria Pure Blue BOH, and the like.

  Of the above, hydroquinone monoalkyl ethers such as hydroquinone monomethyl ether and hydroquinone monobutyl ether, 4,4′-thiobis (3-methyl-6-tert-butylphenol), 2,2′-methylenebis (4-methyl-6-t) Hindered phenols such as -butylphenol) are preferred.

  The content of the polymerization inhibitor in the ink composition is preferably 50 to 30000 ppm, more preferably 100 to 10000 ppm, and more preferably 100 to 3000 ppm with respect to the total amount (total mass) of the ink composition.

-Oxygen scavenger-
The ink composition of the present invention can contain at least one oxygen scavenger. This oxygen scavenger suppresses polymerization inhibition of the polymerizable compound due to oxygen when irradiated with active energy rays in the presence of oxygen, and can favorably promote polymerization and curing and increase curability.

  Examples of the oxygen scavenger include amine compounds and phosphorus compounds, among which amine compounds are preferred. Amine compounds include aliphatic or aromatic primary amine compounds, secondary amine compounds, and tertiary amine compounds.

As the amine compound, an amine compound having 1 to 30 carbon atoms is preferable, and an amine compound having 2 to 24 carbon atoms is more preferable.
In the case of an aliphatic amine compound, the aliphatic group is preferably an aliphatic hydrocarbon group, and preferably a linear, branched, or cyclic aliphatic hydrocarbon group. The aliphatic hydrocarbon group includes an alkyl group and an alkenyl group, preferably an alkyl group. The aliphatic group may have a substituent, and the substituent includes a hydroxyl group. In the case of an aromatic amine compound, the aromatic group is preferably an aromatic hydrocarbon group.

  As the amine compound, not only a monoamine having one nitrogen atom in the molecule but also polyamines having a plurality of nitrogen atoms in the molecule can be used.

Specific examples of the amine compound are listed below.
Examples of the aliphatic primary amine compound include propylamine, isopropylamine, butylamine, amylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, undecylamine, dodecylamine, tridecylamine, and tetradecylamine. , Pentadecylamine, cetylamine, cyclopropylamine, cyclobutylamine, cyclopentylamine, cyclohexylamine, allylamine, monoethanolamine, benzylamine, and the like.

  Examples of the aliphatic secondary amine compound include diethylamine, dipropylamine, diisopropylamine, dibutylamine, diamylamine, dioctylamine, diallylamine, diethanolamine, dicyclohexylamine, N-butylethanolamine, diethylbenzylamine, and the like. It is done.

  Examples of the aliphatic tertiary amine compound include triethylamine, tripropylamine, tributylamine, triamylamine, trioctylamine, triallylamine, N-ethyldiethanolamine, N, N-dibutylethanolamine, triethanolamine, N, N-dimethylethanolamine, tribenzylamine, etc. are mentioned.

  Examples of the aromatic amine compound include aniline, methylaniline, N, N-dimethylaniline, ethylaniline, N, N-diethylaniline, o-toluidine, m-toluidine, p-toluidine, diphenylamine, triphenylamine, α-naphthylamine, β-naphthylamine and the like can be mentioned.

  Examples of polyamines include N, N, N ′, N′-tetramethylethylenediamine, diethylenetriamine, and tetraethylenepentamine.

  Among the amine compounds, N-ethyldiethanolamine, trioctylamine, tetraethylenepentamine, and diethanolamine are preferable, and N-ethyldiethanolamine, tetraethylenepentamine, and trioctylamine are more preferable.

  The content of the oxygen scavenger in the ink composition is preferably 0.1 to 10% by mass and more preferably 1 to 5% by mass with respect to the content of the polymerizable compound described above. By setting the content of the oxygen scavenger in the above range, polymerization inhibition due to oxygen when irradiated with active energy rays in the presence of oxygen can be avoided, and good curability can be ensured.

-UV absorber-
An ultraviolet absorber can be added to the ink composition of the present invention from the viewpoint of improving the weather resistance of the resulting image and preventing discoloration.
Examples of the ultraviolet absorber are described in JP-A Nos. 58-185677, 61-190537, JP-A-2-782, JP-A-5-97075, and JP-A-9-34057. Benzotriazole compounds, benzophenone compounds described in JP-A No. 46-2784, JP-A No. 5194443, US Pat. No. 3,214,463, etc., JP-B No. 48-30492, No. 56-21141 Cinnamic acid compounds described in JP-A-10-88106, JP-A-4-298503, JP-A-8-53427, JP-A-8-239368, JP-A-10-182621, Special Tables The triazine compounds described in JP-A-8-501291, Research Disclosure No. Examples thereof include compounds described in US Pat. No. 24239, compounds that emit fluorescence by absorbing ultraviolet rays typified by stilbene and benzoxazole compounds, and so-called fluorescent brighteners.
The addition amount is appropriately selected according to the purpose, but is generally about 0.01 to 10% by mass with respect to the total amount (total mass) of the ink composition.

-Antioxidant-
An antioxidant may be added to the ink composition of the present invention to improve stability. Examples of the antioxidant include European Published Patent No. 223739, No. 309401, No. 309402, No. 310551, No. 310552, No. 4594416, German Published Patent No. 3435443. JP, 54-85535, 62-262417, 63-113536, 63-163351, JP-A-2-262654, JP-A-2-71262, Examples thereof include those described in Kaihei 3-121449, JP-A-5-61166, JP-A-5-119449, US Pat. No. 4,814,262, US Pat. No. 4,980,275, and the like.
The addition amount is appropriately selected according to the purpose, but is generally about 0.01 to 10% by mass with respect to the total amount (total mass) of the ink composition.

-Anti-fading agent-
In the ink composition of the present invention, various organic and metal complex anti-fading agents can be used. Examples of the organic anti-fading agent include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, and heterocycles. Examples of the metal complex anti-fading agent include nickel complexes and zinc complexes. No. 17643, No. VII, I to J, ibid. 15162, ibid. No. 18716, page 650, left column, ibid. No. 36544, page 527, ibid. No. 307105, page 872, ibid. The compounds described in the patent cited in No. 15162 and the compounds included in the general formulas and compound examples of representative compounds described in JP-A-62-215272, pages 127 to 137 can be used. .
The addition amount is appropriately selected according to the purpose, but is generally about 0.01 to 10% by mass with respect to the total amount (total mass) of the ink composition.

-Conductive salts-
Conductive salts such as potassium thiocyanate, lithium nitrate, ammonium thiocyanate, and dimethylamine hydrochloride can be added to the ink composition of the present invention for the purpose of controlling ejection properties.

-Solvent-
It is also effective to add a very small amount of an organic solvent to the ink composition of the present invention in order to improve the adhesion to the recording medium.
Examples of the solvent include ketone solvents such as acetone, methyl ethyl ketone, and diethyl ketone, alcohol solvents such as methanol, ethanol, 2-propanol, 1-propanol, 1-butanol, and tert-butanol, and chlorine such as chloroform and methylene chloride. Solvents, aromatic solvents such as benzene and toluene, ester solvents such as ethyl acetate, butyl acetate and isopropyl acetate, ether solvents such as diethyl ether, tetrahydrofuran and dioxane, glycols such as ethylene glycol monomethyl ether and ethylene glycol dimethyl ether And ether solvents.
In this case, it is effective to add the solvent within a range that does not cause the problem of solvent resistance and VOC, and the amount is preferably 0.1 to 5% by mass, more preferably based on the total amount (total mass) of the ink composition. Is in the range of 0.1 to 3% by mass.

-Polymer compound-
Various polymer compounds can be added to the ink composition of the present invention in order to adjust film physical properties. Examples of polymer compounds include acrylic polymers, polyvinyl butyral resins, polyurethane resins, polyamide resins, polyester resins, epoxy resins, phenol resins, polycarbonate resins, polyvinyl butyral resins, polyvinyl formal resins, shellacs, vinyl resins, acrylic resins. Rubber resins, waxes and other natural resins can be used. Two or more of these may be used in combination. Of these, vinyl copolymer obtained by copolymerization of acrylic monomers is preferred. Furthermore, a copolymer containing “carboxyl group-containing monomer”, “methacrylic acid alkyl ester”, or “acrylic acid alkyl ester” as a structural unit is also preferably used as the copolymer composition of the polymer binder.

In addition to the above, the ink composition of the present invention includes, for example, leveling additives, matting agents, waxes for adjusting film physical properties, and adhesion to recording media such as polyolefin and PET. In order to improve this, a tackifier or the like that does not inhibit the polymerization can be contained.
As the tackifier, specifically, a high-molecular-weight adhesive polymer described in JP-A-2001-49200, 5-6p (for example, (meth) acrylic acid and an alkyl group having 1 to 20 carbon atoms). Copolymers composed of esters with alcohols having an ester, esters of (meth) acrylic acid with alicyclic alcohols having 3 to 14 carbon atoms, and esters of (meth) acrylic acid with aromatic alcohols having 6 to 14 carbon atoms And low molecular weight tackifying resin having a polymerizable unsaturated bond.

[Preferred physical properties of ink composition]
When the ink composition of the present invention is applied to inkjet recording, the ink viscosity at the temperature at the time of ejection is preferably 5 to 30 mPa · s, and more preferably 7 to 20 mPa · s, in consideration of ejection properties. For this reason, it is preferable to adjust and determine a composition ratio suitably so that it may become the said range.
The viscosity of the ink composition at room temperature (25 ° C.) is preferably 7 to 120 mPa · s, and more preferably 10 to 80 mPa · s. By setting the viscosity at room temperature high, even when a porous recording medium is used, ink penetration into the recording medium can be prevented, uncured monomer can be reduced, and odor can be reduced. Dot bleeding at the time of landing can be suppressed, and as a result, image quality can be improved.

  The surface tension of the ink composition of the present invention is preferably 20 to 40 mN / m, and more preferably 20 to 30 mN / m. In addition, when recording the ink composition of the present invention on various recording media such as polyolefin, PET, coated paper, and uncoated paper, the surface tension is preferably 20 mN / m or more from the viewpoint of bleeding and penetration, and is wet. From the viewpoint of properties, it is preferably 30 mN / m or less.

The ink composition of the present invention can be suitably used as an ink for inkjet recording. There are no particular restrictions on the ink jet recording method, for example, a charge control method that ejects ink using electrostatic attraction, a drop-on-demand method (pressure pulse method) that uses the vibration pressure of a piezo element, and an electrical signal that is acoustic Either an acoustic ink jet system that irradiates ink by irradiating it with ink instead of using a beam, or a thermal ink jet system that uses ink to form bubbles by heating the ink and use the generated pressure. Also good. The inkjet recording method includes a method of ejecting a large number of low-density inks called photo inks in a small volume, a method of improving image quality using a plurality of inks having substantially the same hue and different concentrations, and colorless and transparent. A method using ink.
Among these, the ink is suitable as a drop-on-demand type (pressure pulse type) ink jet recording ink using a piezo element.

<Image forming method and recorded matter thereof>
The image forming method of the present invention includes a step of recording an image on a recording material using the ink composition of the present invention described above (image recording step), and irradiating the recorded image with active energy rays (active rays). And a step of curing (image curing step). In the present invention, active energy rays are used in the image curing step, and after recording an image on a recording material in the image recording step, the recorded images are irradiated with active energy rays, thereby contributing to imaging. Polymerization and curing of the polymerizable compound proceeds, and it is possible to form an image that is cured well and has high fastness.
In the recorded matter obtained with this ink, the image portion is cured by irradiation with radiation such as ultraviolet rays, and the strength of the image portion is excellent. For example, it can be used as an ink receiving layer (image portion) of a lithographic printing plate. it can.

In the recording step, it is preferable to apply an ink jet recording method using an ink jet printer. Specifically, it is preferable that the image recording step records the image by inkjet recording in which the ink composition is discharged.
In the ink jet recording method, image recording is performed on a recording material using the ink composition of the present invention, and there are no particular restrictions on the ink discharge nozzles and the like used at that time, which can be appropriately selected according to the purpose. it can. There is no restriction | limiting in particular in an inkjet recording system, and it is as above-mentioned specifically.

  In the image curing step, an exposure process for accelerating polymerization and curing can be performed using a light source that emits active energy rays in a wavelength region corresponding to the sensitive wavelength of the ink composition. Specifically, a light source that emits active rays belonging to a wavelength region of 240 to 450 nm, for example, LD, LED, fluorescent lamp, low-pressure mercury lamp, high-pressure mercury lamp, metal halide lamp, carbon arc lamp, xenon lamp, chemical lamp, etc. It can be suitably performed. Preferred light sources include LEDs, high pressure mercury lamps, and metal halide lamps. The exposure time and the amount of light may be appropriately selected according to the degree of polymerization and curing of the polymerizable compound according to the present invention.

[Recording material]
As the recording medium of the present invention, both an ink-permeable recording medium and an ink-impermeable recording medium can be used. Examples of the ink-permeable recording medium include plain paper, inkjet exclusive paper, coated paper, electrophotographic co-paper, cloth, non-woven fabric, porous film, and polymer absorber. These are described as “recording materials” in Japanese Patent Application Laid-Open No. 2001-181549.
In order to exhibit the effects of the present invention, it is preferable to use a non-ink-permeable recording medium. Examples of the ink-impermeable recording medium include art paper, synthetic resin, rubber, resin-coated paper, glass, metal, earthenware, and wood. In addition, in order to add each function, a base material obtained by combining a plurality of these materials can be used.
Although any synthetic resin can be used as the synthetic resin, for example, polyethylene terephthalate and polyester such as polybutadiene terephthalate; polyolefin such as polyvinyl chloride, polystyrene, polyethylene, polyurethane, and polypropylene; and acrylic resin, Examples include polycarbonate, acrylonitrile-butadiene-styrene copolymer, diacetate, triacetate, polyimide, cellophane, and celluloid.
The shape (thickness) of the base material using the synthetic resin may be a film shape, a card shape or a block shape, and can be appropriately selected according to a desired purpose without particular limitation. These synthetic resins may be transparent or opaque. As the usage form of the synthetic resin, it is one of the preferred forms used in the form of a film used for so-called soft packaging, and various non-absorbable plastics and films thereof can be used. Examples of various plastic films include PET film, OPS film, OPP film, ONy film, PVC film, PE film, and TAC film.
Examples of the resin-coated paper include a transparent polyester film, an opaque polyester film, an opaque polyolefin resin film, and a paper support in which both sides of the paper are laminated with a polyolefin resin, and both sides of the paper are laminated with a polyolefin resin. A paper support is particularly preferred.

  As described above, according to the image recording using the ink composition of the present invention, a high-quality, high-strength and robust image can be obtained, and the obtained recorded product, that is, the recorded product of the present invention is an image. It has excellent fastness, light resistance and ozone resistance.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples. In this example, an example of producing ink for inkjet recording is shown as an example of the ink composition.

[Examples 1 to 10, Comparative Examples 1 to 5]
A composition containing the monomer, polymerizable compound, polymerization initiator, and colorant described in Table 1 below in the amounts shown in Table 1 was mixed to obtain a dye ink and a pigment ink.

*1 : 3,7-ビス(3-オキセタニル)-5-オキサ-ノナン(東亜合成社製）
*2：3,4-エポキシシクロヘキシルメチル-3',4'-エポキシシクロヘキサンカルボキシレート(ダイセルユーシービー社製）
*3 :1,6-ヘキサンジオールジアクリレート(ダイセルユーシービー社製）
*4 :ジエチレングリコールジアクリレート
*5 :光カチオン重合開始剤；トリフェニルスルフォニウム塩（ダウケミカル社製）
*6 :光ラジカル重合開始剤；アシルフォスフィンオキサイド（ＢＡＳＦジャパン社製）
*7：下記マゼンタ染料Ｍ−１
*8：以下のようにして調製した顔料分散物Ｐ−１

* 1: 3,7-bis (3-oxetanyl) -5-oxa-nonane (manufactured by Toa Gosei Co., Ltd.)
* 2: 3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexanecarboxylate (Daicel UCB)
* 3: 1,6-hexanediol diacrylate (Daicel UCB)
* 4: Diethylene glycol diacrylate
* 5: Photocationic polymerization initiator; triphenylsulfonium salt (manufactured by Dow Chemical Company)
* 6: Photoradical polymerization initiator; Acylphosphine oxide (BASF Japan)
* 7: Magenta dye M-1 below
* 8: Pigment dispersion P-1 prepared as follows

-Preparation of pigment dispersion P-1-
10 g of Pigment Yellow 12, 5 g of polymer dispersant (Avecia Solsprse series), and 85 g of stearyl acrylate were used with a known dispersing device so that the particle size of the pigment particles was in the range of 0.2 to 0.3 μm. Then, pigment dispersion P-1 was obtained using heat filter filtration.

《Image recording and evaluation》
Each ink obtained as described above is loaded into an ink jet printer (printing density 300 dpi, droplet ejection frequency 4 kHz, nozzle number 64), and each ink is ejected onto art paper to record a color image. Using a lamp “SP-7” (manufactured by Ushio Inc.), a color image sample was produced by irradiation under the condition of an exposure energy of 20 mJ / cm ² .
The following evaluation was performed on a sample that had passed 15 minutes after ink ejection. The evaluation results are shown in Table 2 below.

(Discharge stability)
When ink was recorded with an ink jet printer, the ink that could be ejected without problems was evaluated as “A”, and the ink that caused non-ejection was evaluated as “C”.

(Curable)
The seal screen was evaluated by a tack-free test. Specifically, the image (cured film) was touched with a finger and evaluated as “A” when there was no stickiness, “B” when there was slight stickiness, and “C” when marked stickiness.
Further, in the evaluation of A, even when a sample prepared in the same manner except that the exposure energy by the Deep UV lamp was 10 mJ / cm ² was evaluated, the case where there was no stickiness was evaluated as “S”.

(Adhesiveness)
The image (cured film) was cut with a cutter in a grid pattern, and then an adhesive tape was attached to the surface. Subsequently, the adhesive tape was peeled off, and the remaining state of the image (cured film) after peeling was observed visually. The case where peeling is not observed is evaluated as “A”, the case where partial peeling is observed as “B”, the case where significant peeling is observed as “C”, and the case where curing is insufficient and cannot be evaluated as “D”. did.

(Light resistance evaluation)
The art paper on which the image was formed was irradiated with xenon light (100,000 lux) for 3 days using a weather meter (Atlas C.165, manufactured by Atlas). The image density before and after the xenon irradiation was measured using a reflection densitometer (X-Rite 310TR, manufactured by X-Rite) and evaluated as a dye residual ratio.
The reflection density was fixed at 1.0 and measured. The case where the residual ratio of the dye was 80% or more was evaluated as “A”, 70% or more and less than 80% as “B”, and less than 70% as “C”.

(Ink stability)
1 g of the prepared ink was put in a test tube having a diameter of 5 ml and allowed to stand at room temperature for 2 weeks to evaluate ink sedimentation. The case where change was not observed was evaluated as “A”, and the case where sedimentation was observed was evaluated as “C”.

As shown in Table 2, when the ink composition of this example containing a monomer having a photo-ring-opening polymerizable group and a nitrogen-containing heterocyclic structure was used, the ejection stability, curability, Good evaluation could be obtained with respect to adhesion, light resistance and ink stability. Thereby, by using the ink composition of this example, the ink stability is excellent, a good image can be formed, and the curability and the adhesion to the recording medium are excellent when a dye is used as the colorant. It was found that an inkjet recording ink and an inkjet recording method can be provided.
Further, such an ink composition has been found to be less clogged and to have good ink transparency even when printed on a transparent support after curing.
On the other hand, in the comparative ink composition that does not include a monomer having a photo-ring-opening polymerizable group and a nitrogen-containing hetero ring structure, or in the comparative ink composition that includes a radical photopolymerization initiator, all evaluations are made. Good evaluation could not be obtained for the items.

Claims (11)

  An ink composition comprising a monomer having a photo-ring-opening polymerizable group and a nitrogen-containing heterocyclic structure.   The ink composition according to claim 1, wherein the photo-ring-opening polymerizable group is an oxirane group or an oxetane group.   The ink composition according to claim 1, wherein the monomer has two or more photo-ring-opening polymerizable groups.   The ink composition according to claim 1, wherein the nitrogen-containing heterocyclic structure of the monomer is a 5- to 8-membered ring. The ink composition according to claim 1, wherein the monomer is represented by the following general formula (I).

(In the general formula (I), Q represents an atomic group capable of forming a 5- to 8-membered ring with -CON-. L represents a single bond or a divalent linking group. Y represents the photo-ring-opening polymerizable group. N represents 1 or 2, and m represents an integer of 1 to 4.)   The ink composition according to claim 1, further comprising a colorant.   The ink composition according to claim 6, wherein the colorant is a pigment or an oil-soluble dye.   The ink composition according to claim 1, wherein the ink composition is for inkjet printing. An image recording step of recording an image on a recording material using the ink composition according to claim 1;
An image curing step of irradiating and curing an active energy ray on the image recorded on the recording material in the image recording step;
An image forming method comprising:   The image forming method according to claim 9, wherein the image recording step records the image by inkjet recording in which the ink composition is discharged.   A recorded matter comprising the ink composition according to any one of claims 1 to 8.