JP2006274052A - Ink composition, ink jet recording method, and printed article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink composition which uses a cation polymerization initiator and a cation-polymerizable compound, and has excellent curability and temporal stability, and to provide an ink jet recording method and a printed article each using the ink composition. <P>SOLUTION: This ink composition is characterized by comprising a cationic photopolymerization initiator, a styryl group-having cation-polymerizable compound and/or a vinyl ether group-having cation-polymerizable compound, and a radical polymerization inhibitor. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink composition, an ink jet recording method using the ink composition, and a printed material.

  Water-based ink-jet inks have poor water resistance when printed on plain paper and are likely to bleed, and ink droplets are poorly attached when printed on non-water-absorbing recording media such as plastic. For this reason, image formation could not be performed, and drying of the solvent was extremely slow, so that it was necessary to dry without overlapping the recorded material immediately after printing, and the image was liable to blur.

  Ultraviolet curable inks using polyfunctional monomers with excellent adhesion to recording media have been developed as suitable for printing on non-water-absorbing recording media. Slow and insufficient to form a full color image. In order to solve the drying property, a method using a volatile organic solvent as the solvent of the ink has been carried out, but in order to dry quickly, it is highly flammable, such as methyl ethyl ketone and ethanol, and is also highly volatile. It was necessary to use a solvent.

In order to solve these problems, inkjet inks that are cured and fixed by radiation rather than volatilization of the ink solvent have been developed. For example, Patent Documents 1 to 3 disclose inks containing a monomer having a polymerizable group and an oil-soluble dye. Patent Document 4 discloses a photopolymerizable composition containing a photopolymerizable compound and a photopolymerization initiator. However, these inks have a problem that the curing speed is insufficient. In general, since radical polymerization is inhibited by oxygen, the curability in air and in a thin film is a problem.
Therefore, an ink using cationic polymerization that is not inhibited by oxygen is disclosed. For example, Patent Document 5 discloses an active energy ray-curable composition having oxirane, oxetane, and vinyl ether with improved curing speed, but has a problem that storage stability deteriorates.
From the viewpoint of storage stability, Patent Document 6 discloses a technique that improves the temporal stability of a radical polymerization type ink by adding a radical polymerization inhibitor to the ink. When the addition amount of the radical polymerization inhibitor is increased in order to improve the property, there is a problem that the curability deteriorates. Patent Document 7 describes the use of quinones as radical polymerization inhibitors as additives for cationic polymerization ink compositions containing cationically polymerizable compounds. There is no description.
JP 2003-221528 A JP 2003-221532 A JP 2003-221530 A JP 2001-222105 A JP 2001-220526 A JP 2003-127518 A JP 2004-359715 A

  The problem to be solved by the present invention is to provide an ink composition to which a cationic polymerization system using a cationic polymerization initiator and a cationic polymerizable compound is applied, which is excellent in curability and stability over time. It is to be. Moreover, it is providing the inkjet recording method and printed matter using such an ink composition.

As a result of intensive studies to solve the above problems, the present inventors have conceived the following present invention. That is, the ink composition of the present invention contains a photocationic polymerization initiator, a cationically polymerizable compound having a styryl group and / or a cationically polymerizable compound having a vinyl ether group, and a radical polymerization inhibitor. And
Here, in the ink composition of the present invention, the content of the cationic polymerizable compound having a styryl group and / or the cationic polymerizable compound having a vinyl ether group is 5% by mass with respect to the total mass of the ink composition. The range is preferably 95% by mass or less, more preferably 20% by mass or more and 95% by mass or less, and most preferably 30% by mass or more and 70% by mass or less.

  In addition, the ink composition of the present invention may further contain a cationically polymerizable compound other than the cationically polymerizable compound having a styryl group and the cationically polymerizable compound having a vinyl ether group. In this case, the other cationically polymerizable compound is preferably a compound selected from the group consisting of an oxirane compound and an oxetane compound.

Furthermore, the ink composition of the present invention may further contain a colorant, and the colorant may be selected from the group consisting of pigments and oil-soluble dyes.
Here, when an oil-soluble dye is used as the colorant, the oxidation potential of the oil-soluble dye is preferably at least 1.0 V (vs SCE).
Such an ink composition of the present invention is preferably for inkjet recording.

The ink jet recording method of the present invention includes a step of ejecting the ink composition of the present invention to a recording medium by an ink jet printer, and a step of curing the ejected ink composition by irradiating with active radiation. It is a feature.
The printed matter of the present invention is characterized by using the ink composition of the present invention.

The ink composition of the present invention contains a cationically polymerizable compound having a styryl group and / or a cationically polymerizable compound having a vinyl ether group, which is highly reactive and excellent in cationic polymerizability. Can be increased. In general, when an ink composition is stored, radicals are generated in the composition due to the influence of heat or light, and the polymerizable compound may be polymerized due to the influence of the radical. Since the ink composition of the present invention contains a radical polymerization inhibitor capable of selectively taking in radicals generated in the composition, radicals which are not desired even when the ink composition is stored. Polymerization can be effectively suppressed.
From these facts, it is presumed that the ink composition of the present invention can achieve both curability and stability over time. As a result, if the ink composition of the present invention having high ink curability (curing speed is sufficiently fast) and good ink diameter stability is used, there is less clogging and adhesion to a recording medium is improved. Excellent characters and images can be recorded on the recording medium.

According to the present invention, an ink composition to which a cationic polymerization system using a cationic polymerization initiator and a cationic polymerizable compound is applied, and an ink composition excellent in curability and time stability can be provided. .
Moreover, an inkjet recording method and printed matter can be provided using such an ink composition.

Details of the present invention will be described below.
<Ink composition>
The ink composition of the present invention comprises a photocationic polymerization initiator, a cationically polymerizable compound having a styryl group and / or a cationically polymerizable compound having a vinyl ether group, and a radical polymerization inhibitor. .
Hereinafter, each component constituting the ink composition of the present invention will be described.

[Cationically polymerizable compound having a styryl group and a cationically polymerizable compound having a vinyl ether group]
In the present invention, the cationically polymerizable compound having a styryl group and the cationically polymerizable compound having a vinyl ether group can be used regardless of the type of monomer, oligomer or polymer.
In the ink composition of the present invention, it is sufficient that at least one of a cationically polymerizable compound having a styryl group and a cationically polymerizable compound having a vinyl ether group is contained, and two or more kinds may be mixed and used.
The “cationic polymerizable compound” in the present invention refers to a compound that can be polymerized by a cation or a cation radical generated by a photocationic polymerization initiator described later.

Examples of the cationically polymerizable compound having a styryl group include the following, but the present invention is not limited thereto.
Compounds having one styryl group in the molecule, that is, monofunctional compounds include styrene, 2-methylstyrene, 4-methylstyrene, 2,6-methylstyrene, 2-ethylstyrene, 4-ethylstyrene, 2 2-alkyl styrenes such as ethyl styrene, 4-n-butyl styrene, 2-n-butyl styrene, 4-t-butyl styrene, 2-t-butyl styrene, 4-butenyl styrene, 4-octenyl styrene And 4-alkylstyrenes, 4-alkoxystyrenes such as 4-methoxystyrene, 2-methoxystyrene, 4-t-butylstyrene, or 4-alkoxystyrenes, 4-acetoxystyrene, 4-dimethylaminostyrene, 4- Dimethylaminomethylstyrene, 4-glycidylmethylstyrene, 4-hydroxystyrene, 2,4 Dialkyl styrene, 2,4,6-alkylstyrene, 2,4-dialkoxy styrene, 2,4,6-alkoxy styrene.

  As a compound containing two or more styryl groups in the molecule, that is, polyfunctional styrene, divinylbenzene, bis (4-vinylphenyl) methane, bis (4-vinylphenyl) ethane, bis (4-vinylphenyl) butane, Bis (4-vinylphenyl) hexane, bis (4-vinylphenyl) heptane, bis (4-vinylphenyl) octane, bis (4-vinylphenoxy) hexane, bis (4-vinylbenzyl) diethylene glycol, ethylene glycol bis (4 -Vinylphenyl) ether, propylene glycol bis (4-vinylphenyl) ether, 1,6-hexanediol bis (4-vinylphenyl) ether, 1,8-octanediol bis (4-vinylphenyl) ether, oligoethylene glycol Bis (4-vinylphenyl) ester Ether, polyethylene glycol (4-vinylphenyl ether), oligo propylene glycol bis (4-vinylphenyl) ether, polypropylene glycol bis (4-vinylphenyl) ether, glycerol tris (4-vinylphenyl) ether.

Any cationically polymerizable compound having a vinyl ether group may be used as long as at least one vinyl group is substituted with an ether group, and known vinyl ethers can be used. In addition, since vinyl ether derivatives in which the α-position or β-position of the vinyl group is substituted with an electronic ether group or an alkyl group also exhibit the same reactivity as the vinyl ether group, they can be used as the cationic polymerizable compound having a vinyl ether group in the present invention. it can.
Examples of the cationically polymerizable compound having a vinyl ether group include the following, but the present invention is not limited thereto.

  Examples of compounds having one vinyl ether group in the molecule, that is, monofunctional compounds include, for example, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, n-butyl vinyl ether, t-butyl vinyl ether, 2-ethylhexyl vinyl ether, n- Nonyl vinyl ether, lauryl vinyl ether, cyclohexyl vinyl ether, cyclohexyl methyl vinyl ether, 4-methylcyclohexyl methyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenoxyethyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, butoxyethyl vinyl ether, Methoxyethoxyethyl vinyl ether, ethoxyethoxyethyl vinyl ether , Methoxypolyethylene glycol vinyl ether, tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethylcyclohexyl methyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chloroethyl vinyl ether, chloro Examples include butyl vinyl ether, chloroethoxyethyl vinyl ether, phenylethyl vinyl ether, phenoxy polyethylene glycol vinyl ether, and the like.

  Examples of compounds containing two or more vinyl ether groups in the molecule, that is, polyfunctional compounds include, for example, ethylene glycol divinyl ether, diethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, butylene glycol divinyl ether, hexane Divinyl ethers such as diol divinyl ether, bisphenol A alkylene oxide divinyl ether, bisphenol F alkylene oxide divinyl ether; trimethylol ethane trivinyl ether, trimethylol propane trivinyl ether, ditrimethylol propane tetravinyl ether, glycerin trivinyl ether, pentaerythritol tetravinyl ether, Dipentaerythritol Tavinyl ether, dipentaerythritol hexavinyl ether, ethylene oxide-added trimethylolpropane trivinyl ether, propylene oxide-added trimethylolpropane trivinyl ether, ethylene oxide-added ditrimethylolpropane tetravinyl ether, propylene oxide-added ditrimethylolpropane tetravinyl ether, ethylene oxide-added pentaerythritol Examples thereof include polyfunctional vinyl ethers such as tetravinyl ether, propylene oxide-added pentaerythritol tetravinyl ether, ethylene oxide-added dipentaerythritol hexavinyl ether, and propylene oxide-added dipentaerythritol hexavinyl ether.

  The total content of the cationically polymerizable compound having a styryl group and / or the cationically polymerizable compound having a vinyl ether group is based on the total mass of the ink composition from the viewpoint of the curability of the ink composition and the stability over time. The range is preferably 5% by mass to 95% by mass, more preferably 20% by mass to 95% by mass, and most preferably 30% by mass to 95% by mass.

  Moreover, the cationically polymerizable compound which has a styryl group, and the cationically polymerizable compound which has a vinyl ether group can also be used by mixing with another cationically polymerizable compound in the range which does not impair the effect of this invention. In this case, the ratio of the other cationic polymerizable compound to the total cationic polymerizable compound in the ink composition of the present invention is preferably 5% by mass or more and 90% by mass or less, and preferably 10% by mass or more and 90% by mass or less. It is more preferable that the content is 30% by mass or more and 90% by mass or less.

[Other cationic polymerizable compounds]
As other cationically polymerizable compounds that can be used in combination with cationically polymerizable compounds having a styryl group or cationically polymerizable compounds having a vinyl ether group, monomers, oligomers, Any type of polymer can be used.
Examples of other cationically polymerizable compounds include oxirane compounds and oxetane compounds as shown below, but the present invention is not limited to these, and any known cationically polymerizable compound may be a problem. It can be used without. The cationic polymerizable compounds can be used alone or in combination as a mixture for the purpose of adjusting the reaction rate, ink physical properties, cured film physical properties, and the like.

[Oxirane compounds]
The oxirane compound used in the present invention is not particularly limited as long as it has an oxirane group in the molecule, and any known epoxide can be used. Among these, those having a cyclohexene oxide or alkylene oxide skeleton are preferably used from the viewpoint of reactivity.
Examples of monofunctional epoxides used as oxirane compounds in the present invention include phenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, 1,2-butylene oxide, 1,3-butadiene monooxide, 1,2-epoxydodecane, epichlorohydrin, 1,2-epoxydecane, styrene oxide, cyclohexene oxide, 3-methacryloyloxymethylcyclohexene oxide, 3-acryloyloxymethylcyclohexene oxide, 3 -Vinylcyclohexene oxide etc. are mentioned.

  Examples of polyfunctional epoxides used as oxirane compounds in the present invention include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidyl ether, brominated bisphenol F diglycidyl. Ether, brominated bisphenol S diglycidyl ether, epoxy novolac resin, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, 3,4-epoxycyclohexylmethyl-3 ′, 4 '-Epoxycyclohexanecarboxylate, 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexane-meta-dio Sun, bis (3,4-epoxycyclohexylmethyl) adipate, vinylcyclohexylene oxide, 4-vinylepoxycyclohexane, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 3,4-epoxy-6-methylcyclohexyl -3 ′, 4′-epoxy-6′-methylcyclohexanecarboxylate, methylenebis (3,4-epoxycyclohexane), dicyclopentadiene diepoxide, ethylene glycol di (3,4-epoxycyclohexylmethyl) ether, ethylene bis (3,4-epoxycyclohexanecarboxylate), epoxyhexahydrophthalic acid dioctyl, epoxyhexahydrophthalic acid di-2-ethylhexyl, 1,4-butanediol diglycidyl ether, 1 6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ethers, 1,1,3-tetradecadiene dioxide, limonene dioxide, 1 2,7,8-diepoxyoctane, 1,2,5,6-diepoxycyclooctane, and the like.

[Oxetane compounds]
The oxetane compound in the present invention refers to a compound having an oxetane ring, and arbitrarily selected from known oxetane compounds as described in JP-A Nos. 2001-220526, 2001-310937, and 2003-341217 are used. it can.
The compound having an oxetane ring that can be used in the ink composition of the present invention is preferably a compound having 1 to 4 oxetane rings in the structure. By using such a compound, it becomes easy to maintain the viscosity of the ink composition in a good handling property range, and it is possible to obtain high adhesion of the cured ink to the recording medium. .

  Examples of the compound having 1 to 2 oxetane rings in the molecule include compounds represented by the following general formulas (1) to (3).

In the general formulas (1) to (3), R ^a1 is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, an allyl group, an aryl group, a furyl group, or Represents a thienyl group. Here, when two R ^a1 are present in the molecule, they may be the same or different.
Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, and the like. Preferred examples of the fluoroalkyl group include those in which any hydrogen of these alkyl groups is substituted with a fluorine atom. It is done.

In the general formula (1), R ^a2 represents an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, a group having an aromatic ring, an alkylcarbonyl group having 2 to 6 carbon atoms, carbon A C2-C6 alkoxycarbonyl group or a C2-C6 N-alkylcarbamoyl group is represented.
Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the alkenyl group include a 1-propenyl group, a 2-propenyl group, a 2-methyl-1-propenyl group, and 2-methyl. -2-propenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group and the like. Examples of the group having an aromatic ring include phenyl group, benzyl group, fluorobenzyl group, methoxybenzyl group, phenoxyethyl. Groups and the like.
Examples of the alkylcarbonyl group include an ethylcarbonyl group, a propylcarbonyl group, and a butylcarbonyl group. Examples of the alkoxycarbonyl group include an ethoxycarbonyl group, a propoxycarbonyl group, and a butoxycarbonyl group. Examples of the N-alkylcarbamoyl group include an ethylcarbamoyl group, a propylcarbamoyl group, a butylcarbamoyl group, and a pentylcarbamoyl group.

In the general formula (2), R ^a3 represents a linear or branched alkylene group, a linear or branched poly (alkyleneoxy) group, a linear or branched unsaturated hydrocarbon group, a carbonyl group or a carbonyl group. Represents an alkylene group containing a group, an alkylene group containing a carboxyl group, an alkylene group containing a carbamoyl group, or a group shown below.
Examples of the alkylene group include an ethylene group, a propylene group, and a butylene group. Examples of the poly (alkyleneoxy) group include a poly (ethyleneoxy) group and a poly (propyleneoxy) group.
Examples of the unsaturated hydrocarbon group include a propenylene group, a methylpropenylene group, and a butenylene group.

When R ^a3 is the above polyvalent group, R ^a4 is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom, a nitro group, a cyano group, or a mercapto group. , A lower alkyl carboxyl group, a carboxyl group, or a carbamoyl group.
R ^a5 represents an oxygen atom, a sulfur atom, a methylene group, NH, SO, SO ₂ , C (CF ₃ ) ₂ , or C (CH ₃ ) ₂ .
R ^a6 represents an alkyl group having 1 to 4 carbon atoms or an aryl group, and n is an integer of 0 to 2000.
In addition, R ^a7 represents an alkyl group having 1 to 4 carbon atoms, an aryl group, or a monovalent group having the following structure.

In the above formula, R ^a8 is an alkyl group having 1 to 4 carbon atoms or an aryl group, and m is an integer of 0 to 100.

  Examples of the compound having 3 to 4 oxetane rings include compounds represented by the following general formula (4).

In the general formula (4), R ^a1 has the same ^{meaning as} in the general formula (1). In addition, examples of R ^a9 that is a multivalent linking group include branched alkylene groups having 1 to 12 carbon atoms such as groups represented by A to C below, and branched poly groups such as groups represented by D below. (Alkyleneoxy) group or branched polysiloxy group such as a group represented by E below. j is 3 or 4.

In the above A, R ^a10 represents a methyl group, an ethyl group, or a propyl group. Moreover, in said D, p is an integer of 1-10.

  Another embodiment of the oxetane compound that can be suitably used in the present invention includes a compound represented by the following general formula (5) having an oxetane ring in the side chain.

In the general formula (5), R ^a1 and R ^a8 has the same meaning as above R ^a1 and R ^a8. R ^a11 is an alkyl group having 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, or a butyl group, or a trialkylsilyl group, and r is 1 to 4.

  The compound having such an oxetane ring is described in detail in JP-A No. 2003-341217, paragraph numbers [0048] to [0083], and the compounds described herein can be suitably used in the present invention.

<Photocationic polymerization initiator>
The ink composition of the present invention contains a photocationic polymerization initiator. This photocationic polymerization initiator refers to a compound that generates a strong acid upon irradiation with actinic rays or radiation to generate a cation. Examples of such a photocationic polymerization initiator include photoinitiators for photocationic polymerization. Among the compounds generally used as photoacid generators, such as photoinitiators for photoradical polymerization, photodecolorants for dyes, photochromic agents, or microresists, acid is generated by irradiation with actinic rays or radiation. Thus, known compounds that generate cations and mixtures thereof can be appropriately selected and used.

  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 the same action into the main chain or side chain of the polymer, such as US Pat. No. 3,849,137, German Patent No. 3914407, JP 63-26653, JP 55-164824, JP 62-69263, JP 63-1446038, JP 63-163452, JP 62-153853 And compounds described in JP-A No. 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) - can be exemplified linked group a linking group such as. Rd ¹ represents a hydrogen atom or an alkyl group.
Moreover, these organic groups may further have a substituent.

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 preferred is 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. Preferably, it is a C2-C4 perfluoroalkylene group.

The organic group of Rc ^1, Rc ³ ~Rc ^5, and most preferably a 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.

The photoacid generator may be a compound having a plurality of structures represented by the general formula (b1). 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 preferable examples of the compound represented by the general formula (b1) include compounds (b1-1), (b1-2), and (b1-3) described below.

Compound (b1-1) is in which at least one aryl group R ²⁰¹ to R ²⁰³ in formula (b1), 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, and 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.

The alkyl group that the arylsulfonium compound has as necessary is preferably a linear or branched alkyl group having 1 to 15 carbon atoms, such as 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.

Aryl group, alkyl group of R ²⁰¹ to R ^203, cycloalkyl group, an alkyl group (for example, 1 to 15 carbon atoms), a cycloalkyl group (for example, 3 to 15 carbon atoms), an aryl group (for example, 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 may be substituted. Preferred substituents are linear or branched alkyl groups having 1 to 12 carbon atoms, cycloalkyl groups having 3 to 12 carbon atoms, and linear, branched or cyclic alkoxy groups having 1 to 12 carbon atoms, and most preferred. 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, and a pentyl group), and a linear or branched 2-oxoalkyl group or an alkoxycarbonylmethyl group is 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 above 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 non-nucleophilic anion as X ^{− in} the general formula (b1).

The alkyl group as R ^{1c to} R ^7c may be either linear or branched, 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 a cycloalkyl group 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), C3-C8 cyclic alkoxy group (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 alkyl groups or cycloalkyl groups.

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 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, 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.

  Furthermore, 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 photoacid generator include compounds represented by general formulas (b1) to (b3).
Examples of (b) photoacid generators that can be used in the present invention are particularly preferred.

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-2002-122994, paragraphs [0037] to [0063] can also be suitably used in the present invention.

These photocationic polymerization initiators can be used singly or in combination of two or more.
0.1-20 mass% is preferable and, as for content in the ink composition of a photocationic polymerization initiator, it is more preferable that it is the range of 0.5 mass%-10 mass%. If the content of the photocationic polymerization initiator is less than 0.1% by mass, the amount of acid generated is reduced, so that the curability may be lowered, and the content of the photocationic polymerization initiator is more than 20% by mass. If it is increased, the brittleness of the cured product and the generation of acid due to the remaining initiator are problematic, which is not preferable.

<Radical polymerization inhibitor>
The ink composition of the present invention selectively removes radicals in order to suppress undesired radical polymerization during storage and to effectively advance cationic polymerization with a photocationic polymerization initiator and a cationically polymerizable compound. It is essential to contain a radical polymerization inhibitor that can inhibit the uptake and polymerization other than cationic polymerization, that is, the progress of radical polymerization.

Examples of radical polymerization inhibitors having such functions include phenolic hydroxyl group-containing compounds, quinones, N-oxide compounds, piperidine 1-oxyl free radical compounds, pyrrolidine 1-oxyl free radical compounds, N-nitroso. And compounds selected from the group consisting of phenylhydroxylamines and cationic dyes.
Preferred radical polymerization inhibitors include haloid quinone, p-methoxyphenol, di-t-butyl-p-cresol, pyrogallol, resorcinol, catechol, t-butylcatechol, hydroquinone, benzoquinone, 4,4-thiobis (3-methyl- 6-t-butylphenol), 2,2'-methylenebis (4-methyl-6-t-butylphenol), 2,2,6,6-tetramethylpiperidine and its derivatives, di-t-butylnitroxide, 2,2 , 6,6-tetramethylpiperidine-N-oxide and its derivatives, such as piperidine 1-oxyl free radical, 2,2,6,6-tetramethylpiperidine 1-oxyl free radical, 4-oxo-2,2,6 , 6-Tetramethylpiperidine 1-oxyl free radical, 4-H Roxy-2,2,6,6-tetramethylpiperidine 1-oxyl free radical, 4-acetamido-2,2,6,6-tetramethylpiperidine 1-oxyl free radical, 4-maleimide-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 Examples include free radicals, N-nitrosophenylhydroxylamine cerium salt, N-nitrosophenylhydroxylamine aluminum salt, crystal violet, methyl violet, ethyl violet, and Victoria Pure Blue BOH.
The addition amount of these radical polymerization inhibitors is preferably 0.0001% by mass to 1% by mass, more preferably 0.001% by mass to 0.5%, and more preferably 0.001% by mass based on the total amount of the ink composition. % To 0.3% by mass is more preferable. When the amount of the radical polymerization initiator is less than 0.0001% by mass, the action of inhibiting the polymerization is not sufficient, and when it exceeds 1% by mass, the polymerization inhibitor is precipitated at the time of preparing the ink composition or after curing. Or the strength of the ink cured product may be weakened.

<Other ingredients>
Below, various additives can be added to the ink composition of the present invention as necessary. This additive will be described.

[Colorant]
A colorant can be added to the ink composition of the present invention. When a colorant is added, a visible image can be formed, and the printed matter after being cured with active energy rays is excellent in water resistance and solvent resistance because the colorant is covered with a resin.
There is no restriction | limiting in particular in the coloring agent which can be used here, According to a use, well-known various color materials and (pigment, dye) can be selected suitably, and can be used. For example, when forming an image excellent in weather resistance, a pigment is preferable. In addition, it is preferable to use a dye when providing transparency when an image is formed on a transparent film. As the dye, any water-soluble dye and oil-soluble dye can be used as long as they are compatible with the cationic polymerizable compound. However, if the compatibility with the cationic polymerizable compound is poor, the stability of the ink deteriorates. Therefore, it is preferable to use an oil-soluble dye. That is, in the present invention, it is preferable to include a pigment or an oil-soluble dye as a colorant. In addition, an ink composition that does not use a water-soluble colorant is particularly excellent in water resistance.
These colorants are preferably added in an amount of 0.5 to 20% by mass, more preferably 1 to 15% by mass, and still more preferably 5 to 15% by mass in the ink composition.

[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 and inorganic pigments or pigments dispersed in an insoluble resin or the like as a dispersion medium, or the resin is grafted onto 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 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. 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.).

  C. As a thing which exhibits red or magenta color. 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.).

  As a pigment exhibiting blue or cyan, 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).

As a pigment exhibiting green, 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).
As a pigment exhibiting an orange color, 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 the black pigment 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 dispersing 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. be able to.
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 cationic polymerizable compound that 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, it is preferable to use a cationically polymerizable compound as the dispersion medium, and in particular, to select a cationically polymerizable monomer having the lowest viscosity from the viewpoint of dispersion suitability and handling property of the ink composition.

  The average particle diameter of the pigment particles is preferably 0.08 to 0.5 μm, and the maximum particle diameter is preferably 5 μm or less, more preferably 2 μm, and the selection of the pigment, the dispersant, and the dispersion medium; Set the dispersion 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.

  Examples of 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, nitro, Nitroso dyes, acridine dyes, acridinone dyes and the like can be mentioned.

  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 cyan dyes include azomethine dyes such as indoaniline dyes and indophenol dyes, cyanine dyes, oxonol dyes, polymethine dyes such as merocyanine dyes, diphenylmethane dyes, triphenylmethane dyes, carbonium dyes such as 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 dyes may exhibit yellow, magenta, and cyan colors only after a part of the chromophore is dissociated. In this case, the counter cation 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 used in the present invention is preferably oil-soluble. Specifically, it 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 mother core in order to dissolve the necessary amount in the ink composition.
As the oil-solubilizing group, 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 containing branched substituents, aryloxy groups, aryloxycarbonyl Group, arylcarbonyloxy group, arylaminocarbonyl group, arylaminosulfonyl group, arylsulfonylamino group and the like.
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 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 the 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 any color ink 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 cyan dyes 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) are mentioned as preferable examples, 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 JP-A No. 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. It may be used for inks of any color.

(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 Delahay, “New Instrumental Methods in Electrochemistry” (1954, published by Interscience Publishers); J. et al. "Electrochemical Methods" by Bard et al. (1980, published by John Wiley & Sons) and Akira Fujishima et al., "Electrochemical Measurement Methods" (published by Gihodo Publishing Co., Ltd., 1984).

Specifically, the oxidation potential is 1 × 10 ⁻² to 1 × 10 ⁻⁶ mol in a solvent such as dimethylformamide or acetonitrile containing a supporting electrolyte such as sodium perchlorate or tetrapropylammonium perchlorate. / L is dissolved and measured as a value for SCE (saturated calomel electrode) using various voltammetry (polarography using a dropping mercury electrode, cyclic voltammetry, method using a rotating disk electrode, etc.). This value may deviate by several tens of mil volts due to the influence of the liquid potential difference or the liquid resistance of the sample solution, but the reproducibility of the potential can be ensured by inserting a standard sample (for example, hydroquinone). .

  In the present invention, SCE (saturated calomel) is used as a reference electrode in N, N-dimethylformamide (concentration of dye is 0.001 mol / liter) containing 0.1 mol / liter of tetrapropylammonium perchlorate as a supporting electrolyte. Electrode), a value measured using a graphite electrode as a working electrode and a platinum electrode as a counter electrode (vsSCE) was defined as the oxidation potential of the dye.

Such Eox value represents the ease of transfer of electrons from the sample to the electrode, and the larger the value (the higher the oxidation potential), the less transfer of electrons from the sample to the electrode, in other words, the less easy it is to oxidize. Represents. In relation to the structure of the compound, the oxidation potential becomes more noble by introducing an electron withdrawing group, and the oxidation potential becomes lower by introducing an electron donating group. In the present invention, in order to lower the reactivity with ozone as an electrophile, it is desirable to introduce an electron withdrawing group into the dye skeleton to make the oxidation potential more noble.
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.

[Ultraviolet 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-58-185679, JP-A-61-190537, JP-A-2-782, JP-A-5-97075, JP-A-9-34057, and the like. Benzotriazole compounds, benzophenone compounds described in JP-A No. 46-2784, JP-A No. 5-194433, US Pat. No. 3,214,463, etc., JP-B Nos. 48-30492 and 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, JP The triazine compounds described in JP-A-8-501291, Research Disclosure No. Examples thereof include compounds described in No. 24239, compounds that emit ultraviolet light by absorbing ultraviolet rays typified by stilbene and benzoxazole compounds, so-called fluorescent brighteners, and the like.
The addition amount of the ultraviolet absorber is appropriately selected according to the purpose, but is generally about 0.01 to 10% by mass of the ink composition.

〔Antioxidant〕
An antioxidant can be added to improve the stability of the ink composition. 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 of the antioxidant is appropriately selected according to the purpose, but is generally about 0.001 to 1% by 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, VII, I to J, No. 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 of the antifading agent is appropriately selected according to the purpose, but is generally about 0.001 to 5% by 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〕
In order to improve the adhesion to the recording medium, it is also effective to add a very small amount of an organic solvent to the ink composition of the present invention.
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. % Range.

[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.

[Surfactant]
A surfactant may be added to the ink composition of the present invention. Examples of the surfactant include those described in JP-A Nos. 62-173463 and 62-183457. For example, anionic surfactants such as dialkyl sulfosuccinates, alkyl naphthalene sulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene blocks Nonionic surfactants such as copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. An organic fluoro compound may be used in place of the 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.

In addition to this, if necessary, for example, leveling additives, matting agents, waxes for adjusting film physical properties, polymerization to inhibit the adhesion to recording media such as polyolefin and PET, and the like, The tackifier which does not do 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). An ester with an alcohol having, an ester of (meth) acrylic acid with an alicyclic alcohol having 3 to 14 carbon atoms, a copolymer comprising an ester of (meth) acrylic acid with an aromatic alcohol having 6 to 14 carbon atoms) And a low molecular weight tackifying resin having a polymerizable unsaturated bond.

<Preferred physical properties of ink composition>
The ink composition of the present invention preferably has an ink viscosity of 5 to 30 mPa · s, more preferably 7 to 20 mPa · s at the temperature at the time of ejection in consideration of ejection properties, and is in the above range. It is preferable to adjust the composition ratio appropriately. The ink viscosity at 25 to 30 ° C. is 10 to 300 mPa · s, preferably 10 to 100 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, the image quality is improved. If the ink viscosity at 25 to 30 ° C. is less than 10 mPa · s, the effect of preventing bleeding is small, and conversely if it is more than 300 mPa · s, there may be a problem in the delivery of the ink liquid.

  The surface tension of the ink composition of the present invention is preferably 20 to 40 mN / m, more preferably 20 to 30 mN / m. When recording on various recording media such as polyolefin, PET, coated paper, and non-coated paper, 20 mN / m or more is preferable from the viewpoint of bleeding and penetration, and the wettability is preferably 30 mN / m or less.

<Active energy rays>
As active energy rays for proceeding the polymerization of the ink composition of the present invention, α rays, γ rays, X rays, ultraviolet rays, visible rays, electron rays 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.

<Inkjet recording method and inkjet recording apparatus used therefor>
The ink composition of the present invention thus prepared is suitably used as an ink for inkjet recording. When ink jet recording is performed using the ink composition of the present invention, the ink composition of the present invention is ejected onto a recording medium by an ink jet printer, and the ejected ink composition is irradiated with actinic radiation and cured. Process. As a result, characters and / or images are recorded on the recording medium using the ejected ink composition.
In the printed matter obtained using the ink composition of the present invention, the image portion is cured by irradiation with radiation such as ultraviolet rays, and the strength of the image portion is excellent. It can be used for various purposes such as forming an ink receiving layer (image portion).

  Next, an ink jet recording method and an ink jet recording apparatus that can be suitably employed in the present invention will be described below.

  In the ink jet recording method of the present invention, recording is performed using the ink for ink jet recording, but there are no particular limitations on the ink nozzles and the like used at that time, and they can be appropriately selected according to the purpose. The ink jet recording method described in paragraph No. (0247) of JP-A No. 2001-279141 can be used. Particularly preferred are the charge control method, pressure pulse method, and acoustic ink jet method.

  In the ink jet recording method, it is preferable that the ink composition is heated to 40 to 80 ° C. to reduce the viscosity of the ink composition to 5 to 30 mPa · s and then ejected. Stability can be achieved. In general, radiation curable ink compositions generally have a higher viscosity than aqueous inks, so that the viscosity fluctuation range due to temperature fluctuations during printing is large. This viscosity variation of the ink composition directly affects the droplet size and droplet ejection speed as it is, which causes image quality deterioration. Therefore, it is necessary to keep the ink composition temperature as constant as possible during printing. is there. The control range of the ink composition temperature is preferably set temperature ± 5 ° C., more preferably set temperature ± 2 ° C., and further preferably set temperature ± 1 ° C.

  One feature of the ink jet recording apparatus is that it includes a means for stabilizing the temperature of the ink composition, and the portion to be kept at a constant temperature is a piping system from an ink tank (an intermediate tank if there is an intermediate tank) to the nozzle ejection surface. All of the members are targeted.

  The temperature control method is not particularly limited, but for example, it is preferable to provide a plurality of temperature sensors in each piping portion and perform heating control according to the ink composition flow rate and the environmental temperature. Moreover, it is preferable that the head unit to be heated is thermally shielded or insulated so that the apparatus main body is not affected by the temperature from the outside air. In order to shorten the printer start-up time required for heating or to reduce the loss of heat energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

  Next, radiation irradiation conditions will be described. A basic irradiation method is disclosed in JP-A-60-132767. Specifically, a light source is provided on both sides of the head unit, and the head and the light source are scanned by a shuttle method. Irradiation is performed after a certain period of time after ink landing. Further, the curing is completed by another light source that is not driven. In WO99 / 54415, as an irradiation method, a method using an optical fiber or a method in which a collimated light source is applied to a mirror surface provided on the side surface of the head unit to irradiate the recording unit with UV light is disclosed. In the present invention, these irradiation methods can be used.

  In the present invention, the ink composition is heated to a constant temperature, and the time from landing to irradiation is preferably 0.01 to 0.5 seconds, preferably 0.01 to 0.3 seconds. More preferably, the irradiation is performed after 0.01 to 0.15 seconds. Thus, by controlling the time from landing to irradiation to an extremely short time, it is possible to prevent the landing ink from bleeding before being cured. In addition, since the ink composition can be exposed to a porous recording medium before reaching the deep part where the light source does not reach, residual unreacted monomer can be suppressed, and as a result, odor can be reduced. Can do. By using the inkjet recording method described above and the ink composition of the present invention in combination, a great synergistic effect is brought about. In particular, when an ink composition having an ink viscosity of 10 to 300 mP · s at 25 ° C. is used, a great effect can be obtained. By adopting such a recording method, the dot diameter of the landed ink can be kept constant even on various recording media having different surface wettability, and the image quality is improved. In addition, in order to obtain a color image, it is preferable to superimpose in order from the color with the lowest brightness. When inks with low lightness are stacked, it is difficult for the irradiation line to reach the lower ink, and the curing sensitivity is hindered, the residual monomer is increased, odor is generated, and the adhesion is liable to occur. Irradiation can be performed by injecting all colors and exposing them together, but exposure for each color is preferable from the viewpoint of curing acceleration.

  There is no restriction | limiting in particular as an inkjet recording device used for this invention, A commercially available inkjet recording device can be used. That is, in the present invention, recording can be performed on a recording medium using a commercially available inkjet recording apparatus.

[Recording medium]
The ink composition of the present invention can be suitably printed on a known recording medium.
The recording medium to which the ink composition of the present invention can be applied is not particularly limited, and can be used for ordinary plain paper, uncoated paper, coated paper, inkjet special paper, electrophotographic co-paper, and so on, so-called soft packaging. Various non-absorbing resin materials used or resin films formed into a film can be used. Examples of various plastic films include PET film, OPS film, OPP film, ONy film, PVC film, and PE film. TAC film and the like. In addition, examples of the plastic that can be used as a recording medium material include polycarbonate, acrylic resin, ABS, polyacetal, PVA, and rubbers. Metals, glasses, fabrics, ceramics, etc. can also be used as recording media. As the recording material, those described in paragraph numbers [0228] to [0246] of JP-A Nos. 2001-181549 and 2001-279141 can be used.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. Moreover,% in an Example is a mass reference | standard unless there is particular notice.

[Example 1]
The following components were stirred and mixed to prepare a magenta ink.
Cationic polymerizable compound: 4-methoxystyrene 20 g
Photocationic polymerization initiator: 0.8 g triphenylsulfonium compound
(UVI-6992, manufactured by Dow Chemical Co., Ltd.)
-Radical polymerization inhibitor: Di-t-butyl-p-cresol 0.05 g
Colorant: M-1 (the following structure) 0.4 g
(Oxidation potential 1.39V, measured with ALS Model 610A manufactured by CH Instruments)

[Examples 2 to 6 and 8, Comparative Examples 1 to 3]
As in Example 1, the cationically polymerizable compound, the photocationic polymerization initiator, the radical polymerization inhibitor, and the colorant described in Table 1 below were used, and the mass (g) described in Table 1 below was stirred and mixed. Then, magenta ink was adjusted.
In addition, "Aron oxetane (OXT-221)" in Table 1 is a commercial product manufactured by Toagosei Co., Ltd. having the following structure.

Example 7
The following components were stirred and mixed to prepare a yellow ink.
Cationic polymerizable compound: 4-methoxystyrene 5g
Cationic polymerizable compound: 1,4-cyclohexanedimethanol
Divinyl ether 5g
・ Cationically polymerizable compound: Aron oxetane 15g
(OXT-221, manufactured by Toagosei Co., Ltd.)
Photocationic polymerization initiator: 0.8 g triphenylsulfonium compound
(UVI-6992, manufactured by Dow Chemical Co., Ltd.)
-Radical polymerization inhibitor: Di-t-butyl-p-cresol 0.05 g
Colorant: E-1 (pigment dispersion prepared by the following method) 0.4 g

[Preparation of Pigment Dispersion E-1]
10 g of Pigment Yellow 12, 5 g of a polymer dispersant (Solsprse series manufactured by Avecia), and 85 g of stearyl acrylate are dispersed in a known manner so that the particle size of the pigment particles is in the range of 0.2 to 0.3 μm. Dispersion was performed using an apparatus, and then a pigment dispersion (E-1) was prepared using heated filter filtration.

[Evaluation]
The ink compositions obtained in the above Examples and Comparative Examples were evaluated according to the following evaluation items.
The following samples were used in the following evaluation items for curability and adhesiveness.
That is, after printing on art paper with an ink jet printer (printing density 300 dpi, droplet ejection frequency 4 kHz, number of nozzles 64), exposure is performed with a Deep UV lamp (USHIO SP-7) with an energy of 15 mJ / cm ^2. A printed sample was obtained. Samples that had passed 10 minutes after printing were evaluated according to the following evaluation items for curability and adhesiveness.

(Curable)
The printed surface was evaluated by a tack-free test. When the cured film was touched with a finger, the case where there was no stickiness was evaluated as A, the case where there was slightly stickiness was evaluated as B, and the case where it was extremely sticky was evaluated as C.
In the evaluation of A, even when a print sample prepared in the same manner except that the exposure energy by the Deep UV lamp was 7.5 mJ / cm ² was evaluated, the case where there was no stickiness was evaluated as S.

(Adhesiveness)
After cutting the cut surface in a grid pattern with a cutter, an adhesive tape was attached to the surface of the cured film, and then the remaining state of the cured film on the art paper when the adhesive tape was peeled was visually observed. The case where peeling was not observed was evaluated as A, the case where the peeled film was less than 50%, B, the case where the peeled film was 50% or more as C, and the case where the curing was insufficient and could not be evaluated as D.

(transparency)
The ink composition obtained in each of the above Examples and Comparative Examples was printed on a polyethylene terephthalate sheet having a thickness of 100 μm, and then cured by ultraviolet irradiation to form a cured film having a thickness of 10 μm. The property was evaluated visually. A sample having good transparency was evaluated as A, a sample having translucency as B, and a sample having transparency as C.

(Ink stability)
1 g of the ink composition obtained in each of the above Examples and Comparative Examples was put in a 5 ml test tube and allowed to stand at room temperature for 2 weeks to evaluate ink sedimentation. A case where no change was observed was evaluated as A, and a case where sedimentation was observed was evaluated as C.
Each evaluation result is shown in Table 1.

As shown in Table 1, an example in which a radical polymerization inhibitor was added to a cationic polymerization system using a cationically polymerizable compound having a styrene group or a cationically polymerizable compound having a vinyl ether group, and a photocationic polymerization initiator. All of the ink compositions 1 to 8 were able to obtain good evaluations regarding curability, adhesiveness, and ink stability. As a result, the ink composition of the present example is excellent in ink diameter stability, and a good image can be formed by using the ink composition. In addition, it was found that the ink composition of this example can provide an ink for ink jet recording and an ink jet recording method excellent in curability when using a dye as a colorant and adhesiveness to a recording medium.
Moreover, in the ink composition using M-1 as a coloring agent, it turns out that the transparency of an ink is favorable when it prints on a transparent support body.
In contrast, the ink compositions of Comparative Example 1 and Comparative Example 2 that do not contain a radical polymerization inhibitor are excellent in curability and have no problem in adhesion, but have poor ink stability (diameter stability). A good evaluation could not be obtained.
Moreover, although the ink composition of Comparative Example 3 using a cationically polymerizable compound outside the scope of the present invention was excellent in ink stability, it was inferior in curability and adhesiveness and could not be evaluated well.

Claims (10)

  An ink composition comprising a photocationic polymerization initiator, a cationically polymerizable compound having a styryl group and / or a cationically polymerizable compound having a vinyl ether group, and a radical polymerization inhibitor.   The content of the cationic polymerizable compound having a styryl group and / or the cationic polymerizable compound having a vinyl ether group is 5% by mass to 95% by mass with respect to the total mass of the ink composition. The ink composition according to claim 1.   The ink composition according to claim 1, further comprising a cationically polymerizable compound other than the cationically polymerizable compound having a styryl group and the cationically polymerizable compound having a vinyl ether group.   4. The ink composition according to claim 3, wherein the other cationically polymerizable compound is a compound selected from the group consisting of an oxirane compound and an oxetane compound.   The ink composition according to claim 1, further comprising a colorant.   The ink composition according to claim 1, wherein the colorant is selected from the group consisting of a pigment and an oil-soluble dye.   The ink composition according to claim 6, wherein when the colorant is an oil-soluble dye, the oxidation potential of the oil-soluble dye is at least 1.0 V (vs SCE).   The ink composition according to claim 1, wherein the ink composition is for inkjet recording.   A step of ejecting the ink composition according to any one of claims 1 to 8 onto a recording medium by an ink jet printer, and a step of curing the ejected ink composition by irradiating with active radiation. An ink jet recording method comprising:   A printed matter comprising the ink composition according to any one of claims 1 to 8.