JP2006282875A - 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 exhibits excellent curability and high adhesion to a material to be recorded on and permits formation of a fast image hardly peeling off from the material to be recorded on, and a method for forming an image using the ink. <P>SOLUTION: The ink composition comprises a monomer having a fluorene skeleton and two cationically polymerizable groups, a photopolymerization initiator and a coloring agent, where at least either one of the cationically polymerizable groups is any one of an oxirane group, an oxetane group, a vinyloxy group and a styryl group. The method for forming the image comprises using the ink. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  Water-based ink-jet inks have poor water resistance when printed on plain paper and are likely to bleed. In addition, ink droplets adhere poorly 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.

  Ultraviolet curable inks using polyfunctional monomers with excellent adhesion to recording media have been developed as suitable for recording on non-water-absorbing recording media. However, it was slow to dry and was insufficient to form a full-color image. In order to improve the drying property, a method using a volatile organic solvent as an ink solvent has been performed. However, a low-boiling point solvent such as methyl ethyl ketone or ethanol which is quickly dried has a problem in odor.

  On the other hand, an ink jet recording method in which only a polymerizable monomer is used as an ink solvent and a volatile component is eliminated by solidification by radiation after recording, and an ink composition therefor have been proposed. Specifically, there is disclosure relating to an ink containing a monomer having a polymerizable group and an oil-soluble dye (see, for example, Patent Documents 1 to 3).

Moreover, the photopolymerizable composition containing the photopolymerizable compound and photoinitiator is disclosed (for example, refer patent document 4). Furthermore, a curable composition that cures by photocationic polymerization of an oxirane monomer, an oxetane monomer, vinyl ether or the like is disclosed (for example, see Patent Documents 5 to 7).
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

  However, in any of the above, the ink is not sufficiently cured, and depending on the type of the substrate (hereinafter referred to as the recording material) that is the recording medium, the adhesion is poor, and the cured ink is not cured. There is a problem that peels off.

  As described above, when sufficient adhesion between the image and the recording material (in addition to the paper medium, for example, a resin such as metal or PET, or a non-water-absorbing medium such as glass) is not obtained, the image itself is obtained by polymerization and curing. Although the weatherability and high-speed recording properties against light, ozone, etc. can be ensured, the ink forming the image is peeled off and the image is stable for a long period of time. It cannot be held, and the commercial value as a recording material is greatly impaired.

  The present invention has been made in view of the above, an ink composition that is excellent in curability, has high adhesion to a recording material, and can form a robust image that does not easily peel off from the recording material, and the ink composition Can be cured well, has good adhesion, and can form a robust image that does not easily peel off from the recording material (including an inkjet recording method), and is formed by this, and has good adhesion and robustness. It is an object of the present invention to provide a recorded product without stickiness and to achieve the purpose.

The present invention has obtained knowledge that a monomer having both a fluorene skeleton and two cationically polymerizable groups is effective for improving the adhesion between the recording material and the material while being cured well. This has been achieved based on such findings.
Specific means for achieving the above object are as follows.

<1> An ink composition comprising a monomer having a fluorene skeleton and two cationic polymerizable groups, a photopolymerization initiator, and a colorant.
<2> The ink composition according to <1>, wherein at least one of the two cationically polymerizable groups is an oxirane group.
<3> The ink composition according to <1> or <2>, wherein at least one of the two cationically polymerizable groups is an oxetane group.
<4> The ink composition according to any one of <1> to <3>, wherein at least one of the two cationically polymerizable groups is a vinyloxy group.

<5> The ink composition according to any one of <1> to <4>, wherein at least one of the two cationically polymerizable groups is a styryl group.
<6> The ink composition according to any one of <1> to <5>, further including a colorant.
<7> The ink composition according to <6>, wherein the colorant is at least one selected from the group consisting of a pigment and an oil-soluble dye.
<8> The ink composition according to any one of <1> to <7>, which is used for inkjet recording.

<9> An image recording step of recording an image on a recording material using the ink composition according to any one of <1> to <8>, and irradiating the recorded image with active energy rays And an image curing step for curing.
<10> The image forming method (inkjet recording method) according to <9>, wherein the image recording step includes inkjet recording of the image by discharging the ink composition.
<11> A recorded matter comprising the ink composition according to any one of <1> to <8>.

  According to the present invention, an ink composition having excellent curability, high adhesion to a recording material, and capable of forming a robust image that is difficult to peel off from the recording material, and the ink composition are used. It is possible to provide an image forming method (including an ink jet recording method) capable of forming a robust image that has good properties and is not easily peeled off from a recording material, and a recorded material that is formed thereby and has a good adhesion and is free of stickiness. it can.

  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 present invention comprises a monomer having a fluorene skeleton and two cationic polymerizable groups, and a photopolymerization initiator, and after recording an image on a recording material, the recorded image is cured by irradiation with active energy rays. It is configured as possible. Moreover, it can comprise using other components, such as a coloring agent and various additives other than the said component as needed.

-Monomer-
The ink composition of the present invention contains at least one monomer having a fluorene skeleton and two cationic polymerizable groups (hereinafter also referred to as “monomer according to the present invention”). Since this monomer has a fluorene skeleton and two cationically polymerizable groups in the molecule, it can be cured by cationic polymerization, can improve its curability, and has a high degree of adhesion that is difficult to peel off from the recording material. . In addition, the light resistance of the formed image can be improved.

  Preferred examples of the monomer according to the present invention include compounds represented by the following general formula (I).

  In the general formula (I), L represents a divalent linking group, and Y represents a cationic polymerizable group.

The divalent linking group represented by L is not particularly limited, and is a substituted or unsubstituted alkylene group, a substituted or unsubstituted arylene group, a substituted or unsubstituted alkenylene group, a substituted or unsubstituted aralkylene group, -O -, - S -, - COO -, - N (R) CO -, - CO -, - SO 2 -, - CO-, or the like a combination of these. R represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.

  Among these, a preferable divalent linking group is a substituted or unsubstituted alkylene group (particularly preferably a methylene group having 1 to 4 carbon atoms, which may be either substituted or unsubstituted. Examples thereof include an ethylene group, a propylene group, and trimethylene. A divalent linking group in which the alkylene group and —O— are combined.

  The divalent linking groups L and R may have a substituent, and examples of a preferable substituent in the case of having a substituent include a halogen atom (fluorine atom, chlorine atom, bromine atom, iodine atom, etc.). , Cyano group, alkoxy group (methoxy group, ethoxy group, methoxyethoxy group, etc.), aryloxy group (phenoxy group, etc.), alkylthio group (methylthio group, ethylthio group, etc.), acyl group (acetyl group, propionyl group, benzoyl group, etc.) ), Sulfonyl group (methanesulfonyl group, benzenesulfonyl group etc.), acyloxy group (acetoxy group, benzoyloxy group etc.), sulfonyloxy group (methanesulfonyloxy group, toluenesulfonyloxy group etc.), phosphonyl group (diethylphosphonyl group) ), Amide group (acetylamino group, benzoylamide) ), Carbamoyl group (N, N-dimethylcarbamoyl group, N-phenylcarbamoyl group, etc.), alkyl group (methyl group, ethyl group, propyl group, isopropyl group, cyclopropyl group, butyl group, 2-carboxyethyl group, Benzyl group etc.), aryl group (phenyl group, toluyl group etc.), heterocyclic group (pyridyl group, imidazolyl group, furanyl group etc.), alkenyl group (vinyl group, 1-propenyl group etc.) and the like.

  Examples of the cationic polymerizable group represented by Y include an oxirane group, an oxetane group, a vinyloxy group, and a styryl group. Particularly preferred cationic polymerizable groups are an oxirane group and / or an oxetane group.

  Specific examples of the compound (monomer) represented by the general formula (I) [Exemplary compounds (1) to (12)] are shown below. However, the present invention is not limited to these.

  The compound (monomer) represented by the general formula (I) can be easily synthesized from the following fluorene derivatives (M-1) and (M-2). For example, the exemplary compound (1) can be synthesized by the method described in JP-A No. 2001-181276, and the exemplary compound (2) is obtained from the following fluorene derivative (M-1) and oxetane compound (M-3). The derived compound (M-4) can be synthesized by heating with potassium carbonate in DMF, and the exemplified compound (5) is obtained by producing an alkoxide of the following fluorene derivative (M-2) with sodium hydride, It can be synthesized by reacting compound (M-4).

In this invention, it can also be set as the structure which used together with the monomer concerning said this invention together with the other cationically polymerizable compound further as needed.
Other cationically polymerizable compounds can be arbitrarily selected for the purpose of adjusting the degree of polymerizability, the physical properties of the ink composition, and the like within a range not impairing the effects of the present invention.

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.
Hereinafter, preferred oxirane compounds, oxetane compounds, vinyl ethers, or styrenes in the present invention will be described.

~ Oxirane compounds ~
Examples of oxirane compounds include aromatic epoxides, alicyclic epoxides, and aliphatic epoxides. Examples of the aromatic epoxide include di- or polyglycidyl ethers produced by reacting a polyhydric phenol having at least one aromatic nucleus or an alkylene oxide adduct thereof with epichlorohydrin, such as bisphenol A or an alkylene thereof. Examples thereof include di- or polyglycidyl ethers of oxide adducts, di- or polyglycidyl ethers of hydrogenated bisphenol A or alkylene oxide adducts thereof, and novolak-type epoxy resins.
Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

  Examples of the alicyclic epoxide include cyclohexene obtained by epoxidizing a compound having at least one cycloalkane ring such as a cyclohexene ring or a cyclopentene ring with an appropriate oxidizing agent such as hydrogen peroxide or peracid. Preferable examples include an oxide or a cyclopentene oxide-containing compound.

Examples of the aliphatic epoxide include divalent or polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof, and typical examples thereof include diglycidyl ether of ethylene glycol, diglycidyl ether of propylene glycol, or 1, Diglycidyl ether of alkylene glycol such as diglycidyl ether of 6-hexanediol, diglyceryl or its alkylene oxide adduct di or polyglycidyl ether of polyhydric alcohol such as triglycidyl ether, polyethylene glycol or its dioxide of alkylene oxide adduct Diglycidyl of polyalkylene glycol represented by diglycidyl ether of glycidyl ether, polypropylene glycol or alkylene oxide adducts thereof Ether and the like.
Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

  Among the above oxirane compounds, aromatic epoxides and alicyclic epoxides are preferable from the viewpoint of excellent curing speed, and alicyclic epoxides are particularly preferable.

  Moreover, among the oxirane compounds, those having a small number of functional groups are preferred in that they can simultaneously have solubility and viscosity adjusting effects as described above.

  Specifically, examples of monofunctional epoxides 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.

  Examples of polyfunctional epoxides 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-dioxane, bis (3,4-epoxycyclohexylmethyl) ) Adipate, vinylcyclohexene 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, di (3,4-epoxycyclohexylmethyl) ether of ethylene glycol, ethylenebis (3,4-epoxycyclohexanecarboxylate), Dioctyl epoxyhexahydrophthalate, di-2-ethylhexyl epoxyhexahydrophthalate, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, Lintriglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ethers, 1,1,3-tetradecadiene dioxide, limonene dioxide, 1,2,7,8-di Examples include epoxy octane, 1,2,5,6-diepoxycyclooctane, and the like.

~ Oxetane compounds ~
The oxetane compound is a compound having an oxetane ring, and a known oxetane compound described in JP-A Nos. 2001-220526, 2001-310937, and 2003-341217 is arbitrarily selected and used. it can.

  As the oxetane compound that can be used in the ink composition of the present invention, a compound having 1 to 4 oxetane rings in its molecular structure is preferable. Among them, from the viewpoint of viscosity and adhesiveness of the ink composition, 1 oxetane ring is preferable. A compound having one is preferred. By selecting and using this compound in particular, it is easy to maintain the viscosity of the ink composition within a good handling range, and higher adhesion to the ink recording material after curing. Obtainable.

  Examples of monofunctional oxetane compounds include 3-ethyl-3-hydroxymethyloxetane, 3- (meth) allyloxymethyl-3-ethyloxetane, and (3-ethyl-3-oxetanylmethoxy) methylbenzene. 4-fluoro- [1- (3-ethyl-3-oxetanylmethoxy) methyl] benzene, 4-methoxy- [1- (3-ethyl-3-oxetanylmethoxy) methyl] benzene, [1- (3-ethyl -3-Oxetanylmethoxy) ethyl] phenyl ether, isobutoxymethyl (3-ethyl-3-oxetanylmethyl) ether, isobornyloxyethyl (3-ethyl-3-oxetanylmethyl) ether, isobornyl (3-ethyl-3 -Oxetanylmethyl) ether, 2-ethylhexyl (3- Ru-3-oxetanylmethyl) ether, ethyl diethylene glycol (3-ethyl-3-oxetanylmethyl) ether, dicyclopentadiene (3-ethyl-3-oxetanylmethyl) ether, dicyclopentenyloxyethyl (3-ethyl-3- Oxetanylmethyl) ether,

Dicyclopentenyl (3-ethyl-3-oxetanylmethyl) ether, tetrahydrofurfuryl (3-ethyl-3-oxetanylmethyl) ether, tetrabromophenyl (3-ethyl-3-oxetanylmethyl) ether, 2-tetrabromophenoxy Ethyl (3-ethyl-3-oxetanylmethyl) ether, tribromophenyl (3-ethyl-3-oxetanylmethyl) ether, 2-tribromophenoxyethyl (3-ethyl-3-oxetanylmethyl) ether, 2-hydroxyethyl (3-ethyl-3-oxetanylmethyl) ether, 2-hydroxypropyl (3-ethyl-3-oxetanylmethyl) ether, butoxyethyl (3-ethyl-3-oxetanylmethyl) ether, pentachlorophenyl (3-ethyl-3 − Kisetanirumechiru) ether, pentabromophenyl (3-ethyl-3-oxetanylmethyl) ether, bornyl (3-ethyl-3-oxetanylmethyl) ether, and the like.

  Examples of polyfunctional oxetane compounds include 3,7-bis (3-oxetanyl) -5-oxa-nonane and 3,3 ′-(1,3- (2-methylenyl) propanediylbis (oxymethylene)). Bis- (3-ethyloxetane), 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene, 1,2-bis [(3-ethyl-3-oxetanylmethoxy) methyl] ethane, 1 , 3-bis [(3-ethyl-3-oxetanylmethoxy) methyl] propane, ethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, dicyclopentenylbis (3-ethyl-3-oxetanylmethyl) ether, Triethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, tetraethylene glycol bis (3- Ru-3-oxetanylmethyl) ether, tricyclodecanediyldimethylene (3-ethyl-3-oxetanylmethyl) ether, trimethylolpropane tris (3-ethyl-3-oxetanylmethyl) ether, 1,4-bis (3 -Ethyl-3-oxetanylmethoxy) butane, 1,6-bis (3-ethyl-3-oxetanylmethoxy) hexane, pentaerythritol tris (3-ethyl-3-oxetanylmethyl) ether, pentaerythritol tetrakis (3-ethyl- 3-oxetanylmethyl) ether, polyethylene glycol bis (3-ethyl-3-oxetanylmethyl) ether, dipentaerythritol hexakis (3-ethyl-3-oxetanylmethyl) ether, dipentaerythritol pentakis (3-ethyl) -3-oxetanylmethyl) ether, dipentaerythritol tetrakis (3-ethyl-3-oxetanylmethyl) ether, caprolactone-modified dipentaerythritol hexakis (3-ethyl-3-oxetanylmethyl) ether, caprolactone-modified dipentaerythritol pentakis (3-ethyl-3-oxetanylmethyl) ether, ditrimethylolpropanetetrakis (3-ethyl-3-oxetanylmethyl) ether, ethylene oxide modified bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether, propylene oxide modified bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether, ethylene oxide modified hydrogenated bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether And polyfunctional oxetanes such as propylene oxide-modified hydrogenated bisphenol A bis (3-ethyl-3-oxetanylmethyl) ether and ethylene oxide-modified bisphenol F (3-ethyl-3-oxetanylmethyl) ether.

~ Vinyl ethers ~
Vinyl ethers may be monofunctional or polyfunctional.
Specific examples of monofunctional vinyl ethers include 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, chlorobutyl vinyl ether, chloro Examples thereof include ethoxyethyl vinyl ether, phenylethyl vinyl ether, phenoxy polyethylene glycol vinyl ether, and the like.

  Examples of polyfunctional vinyl ethers include ethylene glycol divinyl ether, diethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, butylene glycol divinyl ether, hexanediol divinyl ether, bisphenol A alkylene oxide divinyl ether, bisphenol F alkylene oxide divinyl ether, etc. Divinyl ethers of: trimethylolethane trivinyl ether, trimethylolpropane trivinyl ether, ditrimethylolpropane tetravinyl ether, glycerin trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinyl ether, dipentaerythritol hexavinyl ether Ter, 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 tetravinyl ether, propylene oxide-added penta And polyfunctional vinyl ethers such as erythritol tetravinyl ether, ethylene oxide-added dipentaerythritol hexavinyl ether, and propylene oxide-added dipentaerythritol hexavinyl ether.

~ Styrenes ~
Specific examples of styrenes 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 benzoic 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, octenyl Styrene, 4-t-butoxycarbonyl styrene, 4-methoxystyrene, 4-t-butoxystyrene, and the like.

The content of the monomer having a fluorene skeleton and two cationically polymerizable groups in the ink composition is preferably 0.5 to 95% by mass, and preferably 3 to 50% by mass with respect to the total solid content of the ink composition. % Is more preferable. When the amount of the monomer according to the present invention is within the above range, it is effective for improving curability, and a robust image that has good adhesion to the recording material and hardly peels off can be obtained. Moreover, the light resistance of the formed image is also excellent.
In addition, when other cation polymerizable compound is used in combination with the monomer according to the present invention, the other cation polymerizable compound can be used within a range that does not impair the effects of the present invention, but with respect to the total mass of the ink composition. And it is preferable that it is 5-95 mass%, and it is more preferable that it is 50-90 mass%.

-Photopolymerization initiator-
The ink composition of the present invention contains 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 the same action 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.

  Further preferred examples of the component (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, 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, 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 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 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, 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), 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.

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.

  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-2002-122994, paragraphs [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.

-Colorant-
The ink composition of the present invention can further be suitably configured so as to contain a colorant and form a visible image. There is no restriction | limiting in particular in this coloring agent, According to a use etc., a well-known various coloring material (especially pigment, dye) can be selected suitably, and can be used. Dyes include water-soluble dyes and oil-soluble dyes, and oil-soluble dyes are preferred in the present invention. Hereinafter, it demonstrates in detail centering on dye and a pigment.

<dye>
As the dye, conventionally known dyes can be appropriately selected and used. 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 above 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 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, so-called water-insoluble oil-soluble dyes are 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 groups include long-chain or branched alkyl groups, long-chain or branched alkoxy groups, long-chain or branched alkylthio groups, long-chain or branched alkylsulfonyl groups, long-chain or branched acyloxy groups, long-chain or branched alkoxycarbonyl groups. A long chain or branched acyl group, a long chain or branched acylamino group, a long chain or branched alkylsulfonylamino group, a long chain or branched alkylaminosulfonyl group, and an aryl group containing these long chain or branched groups, an aryloxy group, An aryloxycarbonyl group, an arylcarbonyloxy group, an arylaminocarbonyl group, an arylaminosulfonyl group, an arylsulfonylamino group, etc. are mentioned.

  In addition, a water-soluble dye having a carboxylic acid group or a sulfonic acid group is converted into an oil-solubilizing alkoxycarbonyl group, aryloxycarbonyl group, alkylaminosulfonyl group using a long-chain or branched alcohol, amine, phenol, or aniline derivative. The 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 selecting a low melting point dye as the oil-soluble dye, dye crystal precipitation in the ink composition is suppressed, and the storage stability of the ink composition can be improved.

  In addition, it is desirable that the oxidation potential is noble (high) in order to improve the resistance to the discoloration, in particular, the oxidizing substance such as ozone and the curing characteristics. For this reason, as the oil-soluble dye, those having an oxidation potential nobler than 1.0 V (vs SCE) are preferable. A higher oxidation potential is preferable, an oxidation potential of 1.1 V (vs SCE) or higher is more preferable, and a voltage of 1.15 V (vs SCE) or higher is particularly preferable.

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 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 general formulas (M-1) to (M-2) described in paragraph numbers [0084] to [0122] of JP-A No. 2002-121414. Examples thereof include compounds described in JP-A No. 2002-121414, paragraph numbers [0123] to [0132]. 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 preferable, and specific examples thereof include paragraphs [0052] to [0066] of JP-A No. 2001-181547 and JP-A No. 2002. And the compounds described in paragraph Nos. [0079] to [0081] of JP-A-1221414.
Particularly preferred dyes are phthalocyanine dyes represented by general formulas (CI) and (C-II) described in paragraph numbers [0133] to [0196] of JP-A No. 2002-121414, A phthalocyanine dye represented by (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. As for this method, for example, “New Instrumental Methods in Electrochemistry” by P. Delahay (1954, published by Interscience Publishers), AJBard et al. “Electrochemical Methods” (1980, published by John Wiley & Sons), Akira Fujishima et al. It is described in the book "Electrochemical measurement method" (1984, published by Gihodo Publisher).

The oxidation potential is determined by dissolving 1 × 10 ⁻² to 1 × 10 ⁻⁶ mol / liter of the test sample in a solvent such as dimethylformamide or acetonitrile containing a supporting electrolyte such as sodium perchlorate or tetrapropylammonium perchlorate. The voltammetry apparatus approximates the oxidation wave when carbon (GC) is swept to the oxidation side (noble side) using carbon (GC) as the working electrode and the rotating platinum electrode as the counter electrode. The intermediate potential value of the line segment formed by the intersection of the straight 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) is a value for the SCE (saturated calomel electrode). Measure as 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 transfer of electrons from the sample to the electrode. The greater the value of Eox, that is, the higher the oxidation potential, the less transfer of electrons from the sample to the electrode, in other words, oxidation. Indicates difficult.

  Specific examples of suitable dyes in the present invention are shown below. However, the present invention is not limited to these specific examples.

<Pigment>
Next, the pigment will be described in detail. The pigment is not particularly limited, and all commercially available organic pigments and inorganic pigments, or insoluble resins etc. dispersed in a pigment as a dispersion medium, and the resin grafted on the pigment surface And the like. Moreover, what dye | stained the resin particle with dye can be used.

  Examples of pigments include “Dictionary of Pigments” (edited by Seijiro Ito, 2000), W. Herbst, K. Hunger “Industrial Organic Pigments”, JP 2002-12607 A, JP 2002-188025 A, Examples thereof include pigments described in JP2003-26978A and JP2003-342503A.

  Specific examples of organic pigments and inorganic pigments include C.I. I. Pigment Yellow 1 (Fast Yellow G, etc.), C.I. I. Monoazo pigments such as CI 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 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, C.I. I. Pigment yellow 93, C.I. I. Condensed azo pigments such as C.I. Pigment Yellow 95 (condensed azo yellow GR and the like), C.I. I. Pigment Yellow 115 (quinoline yellow lake, etc.), etc., acidic dye lake pigments, C.I. 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.), C.I. I. And metal complex salt azomethine pigments such as CI Pigment Yellow 117 (copper azomethine yellow and the like).

  As C.I. red or magenta color, C.I. I. Monoazo pigments such as CI Pigment Red 3 (Toluidine Red, etc.); I. Disazo pigments such as CI 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. Pigment Red 174 (Phloxine B Lake, etc.) and other acidic dye lake pigments; 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 CI Pigment Red 88 (Thioindigo Bordeaux, etc.), C.I. I. Perinone pigments such as CI Pigment Red 194 (perinone red, etc.); I. Perylene pigments such as C.I. Pigment Red 149 (perylene scarlet, etc.), C.I. I. Pigment violet 19 (unsubstituted quinacridone), C.I. I. Quinacridone pigments such as C.I. Pigment Red 122 (quinacridone magenta, etc.); I. Pigment Red 180 (Isoindolinone Red 2BLT, etc.), etc., isoindolinone pigments, C.I. I. And alizarin lake pigments such as CI Pigment Red 83 (Madder 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 (such as Biclothia Pure Blue BO Lake); I. Anthraquinone pigments such as C.I. Pigment Blue 60 (Indantron Blue, etc.); I. And alkaline 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. Pigment Orange 66 (Isoindoline Orange) and the like, C.I. 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.

Further, as white pigments, 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).

  Here, titanium oxide has a smaller specific gravity than other white pigments, a large refractive index, and is chemically and physically stable. Therefore, it has a high hiding power and coloring power as a pigment, and further has an acid or alkali. Excellent durability against other environments. Therefore, titanium oxide is suitable as the white pigment. Moreover, other white pigments (may be other than the listed white pigments) may be contained as required.

  The pigment can be used as a dispersion dispersed in a dispersion medium together with a dispersant as required. For dispersing the pigment, for example, a ball mill, sand mill, attritor, roll mill, jet mill, homogenizer, paint shaker, kneader, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, etc. A dispersing device can be used.

When dispersing the pigment, it is possible to add a dispersant or a dispersion aid.
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, a fatty acid An aromatic polyvalent carboxylic acid, a naphthalenesulfonic acid formalin condensate, a polyoxyethylene alkyl phosphate ester, a pigment derivative, and the like can be given. Commercially available polymer dispersants such as Solsperse series manufactured by Lubrizol can also be suitably used.
As the dispersion aid, a synergist corresponding to various pigments can be used.
The dispersant and the dispersion aid are preferably added in the range 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, or a solvent-free solvent may be used and the polymerizable compound described above, which is a low molecular weight component, may be used as the dispersion medium. However, the ink composition of the present invention is a radiation curable ink and is preferably solvent-free because it is cured after the ink composition is applied onto a recording material. This is because if the solvent remains in the cured ink image, the solvent resistance is deteriorated or a problem of VOC (Volatile Organic Compound) of the remaining solvent occurs. From such a viewpoint, a polymerizable compound is used as the dispersion medium, and it is preferable to select a polymerizable compound having the lowest viscosity among them in terms of dispersion suitability and handling property of the ink composition.

  The average particle size of the pigment is preferably in the range of 0.08 to 0.5 μm, and the selection of the pigment, the dispersant, the dispersion medium, the dispersion conditions, and the filtration so that the maximum particle size is 10 μm or less, preferably 3 μm or less. It is desirable to set conditions. By controlling the particle size in this way, clogging of the head nozzle can be suppressed, and ink storage stability, ink transparency, and curing sensitivity can be maintained.

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

-Additives-
In the ink composition of the present invention, in addition to the above-described components, a sensitizing dye, a co-sensitizer, an ultraviolet absorber, etc. may be used in combination as additives and other components as required for the purpose and application. Can do. Hereinafter, the additive and other 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 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 present 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 , and R ⁵⁰ represents an alkyl group or an aryl group. L ¹ represents a nonmetallic atomic group that forms a basic nucleus of a dye together with adjacent A ¹ and adjacent carbon atoms. 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 the 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 W in the general formula (vi).

In the 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 the dye together with adjacent A ² and carbon atoms. R ⁵³ , R ⁵⁴ , R ⁵⁵ , R ⁵⁶ , R ⁵⁷ and R ⁵⁸ each independently represent a monovalent nonmetallic atomic group.

In the 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. A substituted alkyl group or a substituted or unsubstituted aryl group is represented. L ⁴ and L ⁵ each independently represent a nonmetallic atomic group that forms a basic nucleus of a dye together with A ³ or A ⁴ and an adjacent carbon atom. R ⁶⁰ and R ⁶¹ each independently represent a hydrogen atom or a monovalent nonmetallic atomic group, and R ⁶⁰ and R ⁶¹ may be bonded to each other to form an aliphatic or aromatic ring. .

In the general formula (x), R ⁶⁶ represents an aromatic ring or a hetero 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.

  Hereinafter, preferable specific examples of the compounds represented by the general formulas (vi) to (x) will be given. However, the present invention is not limited to these.

The said sensitizing dye may be used individually by 1 type, and may use 2 or more types together.
The content of the sensitizing dye in the ink composition 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 composition, and preferably 0.1 to 0.1% by mass. -15 mass% is more preferable, More preferably, it is the range of 0.5-10 mass%. Further, the content ratio (a / c) in the ink composition of the sensitizing dye (a) and the photopolymerization initiator (c) is an improvement in the decomposition rate of the photopolymerization initiator and the transmittance of the irradiated light. From the viewpoint, a / c = 100 to 0.5 is preferable in terms of mass ratio, a / c = 50 to 1 is more preferable, and a / c = 10 to 1.5 is 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, JP-A-5-142772, 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.

-Oxygen scavenger-
The ink composition of the present invention can contain at least one oxygen scavenger. This oxygen scavenger suppresses polymerization inhibition of the monomer according to the present invention and other cationic polymerizable compounds by oxygen when irradiated with active energy rays in the presence of oxygen, and promotes polymerization curing well. Curability can be improved.

  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 is 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 above 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 with respect to the content of the monomer according to the present invention described above (and other cationically polymerizable compound if necessary), 1-5 mass% is more preferable. 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.

-Surfactant-
A surfactant can 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. 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.

-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-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 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-
Various organic and metal complex anti-fading agents can be added to the ink composition of the present invention. Examples of the organic anti-fading agent include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, and heterocycles. Examples of the anti-fading agent based on the metal complex include nickel complexes, zinc complexes, and the like. No. 17643, Nos. VII to I, J. 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-
In order to improve the adhesion to the recording material, 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, 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 (polymers) can be added to the ink composition of the present invention in order to adjust film physical properties.
High molecular 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, rubber resins. , Waxes and other natural resins. 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 suitable as the copolymer composition of the polymer binder.

In addition to the above, the ink composition of the present invention has, for example, leveling additives, matting agents, waxes for adjusting film properties, polyolefins, and adhesion to recording materials such as PET. For the purpose of improving, a tackifier or the like that does not inhibit 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 desirable to adjust and determine a composition ratio suitably so that it may become the said range.
In addition, 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 material is used, ink penetration into the recording material 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.
Further, when recording the ink composition of the present invention on various recording materials 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, In terms of wettability, 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 an image recording step of recording an image on a recording material using the ink composition of the present invention described above, and curing by irradiating the recorded image with active energy rays (active rays). And an image curing step to be provided. In the present invention, a polymerizable compound that contributes to imaging by using an active energy ray in an image curing step and recording an image on a recording material in an image recording step and then irradiating the recorded image with the active energy ray. As the polymerization and curing proceed, the image is cured well and an image having high fastness can be formed.
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 image recording step, it is preferable to apply an ink jet recording method using an ink jet printer. Specifically, an aspect in which the image is inkjet-recorded by discharging an ink composition in the image recording step is preferable. In the ink jet recording method, image recording is performed on a recording material using the ink composition of the present invention, but there are no particular restrictions on the ink discharge nozzles (for example, for an ink jet printer) used at that time, and the purpose and application It can be appropriately selected according to the like. 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. What is necessary is just to select an exposure time and light quantity suitably according to the grade of the polymerization hardening of the polymeric compound which concerns on this invention.

-Recording material-
As the recording material, either an ink-permeable recording material or an ink-impermeable recording material can be used.

  Examples of the ink-permeable recording material 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.

  From the viewpoint of effectively expressing the effects of the present invention, it is preferable to use a non-ink-permeable (non-absorbing) recording material. Examples of the ink-impermeable recording material include art paper, synthetic resin, rubber, resin-coated paper, glass, metal, earthenware, and wood. In addition, in terms of adding each function, a base material obtained by combining a plurality of these materials can also be used.

As the synthetic resin, any synthetic resin can be used. For example, polyester resins such as polyethylene terephthalate and polybutadiene terephthalate; polyolefin resins such as polyvinyl chloride, polystyrene, polyethylene, polyurethane, and polypropylene; and acrylic resins, Examples include polycarbonate, acrylonitrile-butadiene-styrene copolymer, diacetate, triacetate, polyimide, cellophane, and celluloid.
There is no restriction | limiting in particular about the shape of the base material using a synthetic resin, and its thickness, Any of a film form, a card | curd shape, or a block shape may be sufficient, and it can select suitably according to the desired objective. The synthetic resin may be either 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 plastics films include PET films, OPS films, OPP films, ONy films, PVC films, PE films, and TAC films.

  Examples of the resin-coated paper include a paper support in which one side or both sides of the paper is coated with a polyolefin resin and the like, and a paper support in which both sides of the paper are laminated with a polyolefin resin is particularly preferable.

  As described above, according to the image recording using the ink composition of the present invention (the image forming method of the present invention), it is possible to obtain a robust image that is highly cured and has good adhesion and is difficult to peel off from the recording material. The obtained recorded matter, that is, the recorded matter of the present invention has good adhesion and is robust and has no stickiness.

  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 1-10, Comparative Examples 1-5)
For each example and each comparative example, the monomer, photopolymerization initiator, and colorant described in Table 1 below were stirred and mixed to obtain a dye ink or pigment ink.

* 1: 3,7-bis (3-oxetanyl) -5-oxa-nonane (manufactured by Toa Gosei Co., Ltd.)
* 2: 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate (manufactured by Daicel UCB)
* 3: 1,6-hexanediol diacrylate (manufactured by Daicel UC Corporation)
* 4: Diethylene glycol diacrylate * 5: Triphenylsulfonium salt (manufactured by Dow Chemical Co .; photocationic polymerization initiator)
* 6: Acylphosphine oxide (BASF Japan, photo radical polymerization initiator)
* 7: Dye M-1 below
* 8: Pigment dispersion P-1 prepared as follows
C. I. 10 g of Pigment Yellow 12, 5 g of a polymer dispersant (Solsprse series, manufactured by Avecia), and 85 g of stearyl acrylate so that the particle diameter of the pigment particles is in the range of 0.2 to 0.3 μm using a known dispersing device. And then heated and filtered.

(Image recording and evaluation)
Each dye ink or pigment ink obtained in each example and each comparative example was sequentially loaded into an ink jet printer (printing density 300 dpi, droplet ejection frequency 4 kHz, nozzle number 64), and each ink was ejected onto art paper. A color image was recorded, and after recording, a deep UV lamp SP-7 (manufactured by Ushio Inc.) was used for irradiation at an exposure energy of 15 mJ / cm ² to prepare a color image sample having a density of about 1.0. . Then, the following evaluation was performed for each of the color image samples after 10 minutes had passed since recording. The evaluation results are shown in Table 2 below.

1. Ejection stability Ejectability when dye ink or pigment ink was loaded on an ink jet printer and printed was observed visually and evaluated according to the following evaluation criteria.
[Evaluation criteria]
A: The discharge could be performed satisfactorily without any trouble.
B: Somewhat hindered.
C: Discharge failure occurred.

2. Curability The surface of the color image sample was evaluated by the following tack-free test. That is, the surface of the color image, which is a cured film immediately after irradiation after recording, was touched with a finger, and the presence or absence of stickiness was subjected to sensory evaluation according to the following evaluation criteria. The smaller the stickiness, the better the curing speed. In addition, when the color image sample prepared in the same manner except that the exposure energy by the Deep UV lamp is 7.5 mJ / cm ² among the evaluations of A is “S”, As evaluated.
[Evaluation criteria]
A: Stickiness was not recognized.
B: Slight stickiness was observed, but there was no practical problem.
C: Remarkably sticky.
S: The color image sample when 7.5 mJ / cm ² was used was not sticky.

3. Adhesion After making a grid-like cut with a cutter on a color image sample that is a cured film, apply adhesive tape to the entire surface of the color image and remove the color image remaining on the art paper when the adhesive tape is peeled off. The remaining state was visually observed and evaluated in four stages according to the following evaluation criteria.
[Evaluation criteria]
A: Peeling of the color image was hardly recognized.
B: Peeling of the color image was partially observed, but was practically unimpeded.
C: Remarkable peeling was recognized and was not acceptable in practical use.
D: Evaluation was not possible due to insufficient curing.

4). Light resistance For each art paper on which a color image was recorded, the color image density (D ⁰ ) was measured in advance using a reflection densitometer (X-Rite 310TR), and then using a Xenon Weather-ometer Ci65A (manufactured by ATLAS). Xenon light (100,000 lux) was irradiated for 3 days, and the color image density (D ¹ ) after irradiation with xenon light was measured again by the same method as described above. A dye residual ratio (%; D ¹ / D ⁰ × 100) was determined from the obtained concentrations D ⁰ and D ¹ and evaluated in three stages according to the following evaluation criteria. The reflection density before irradiation of each color image sample was fixed at 1.0.
[Evaluation criteria]
A: The pigment residual ratio was 80% or more.
B: Dye remaining ratio was 70% or more and less than 80%.
C: The pigment residual ratio was less than 70%.

5. Ink stability 1 g of the obtained dye ink or pigment ink was put in a test tube having a diameter of 5 mm, and allowed to stand at room temperature for 2 weeks. The sedimentation of the ink was evaluated according to the following evaluation criteria.
[Evaluation criteria]
A: No change was seen.
B: Slight sedimentation was observed.
C: Sedimentation was observed.

  As shown in Table 2, in each of the dye ink or pigment ink of each Example containing a monomer having a fluorene skeleton and two cationic polymerizable groups, all of the ejection stability, curability, adhesiveness, light resistance, and Excellent ink stability. Thus, by using the inks of the examples, it is possible to stably obtain an image having high curability and excellent adhesion to the recording material and high light resistance. In addition, there were few ejection failures due to clogging during recording, and the color image after curing had transparency, which was suitable for recording on a transparent support.

  In contrast, comparative dye inks or pigment inks that do not contain a monomer having a fluorene skeleton and two cationically polymerizable groups, or comparative dye inks using a radical polymerization initiator, are particularly hard and adhesive. In the case of using a radical polymerization initiator, the light resistance was further inferior. Therefore, the comparative dye ink or pigment ink could not satisfy all of ejection stability, curability, adhesiveness, light resistance, and ink stability.

Claims (11)

  An ink composition comprising a monomer having a fluorene skeleton and two cationically polymerizable groups, and a photopolymerization initiator.   The ink composition according to claim 1, wherein at least one of the two cationically polymerizable groups is an oxirane group.   The ink composition according to claim 1 or 2, wherein at least one of the two cationically polymerizable groups is an oxetane group.   The ink composition according to claim 1, wherein at least one of the two cationically polymerizable groups is a vinyloxy group.   The ink composition according to claim 1, wherein at least one of the two cationically polymerizable groups is a styryl group.   The ink composition according to any one of claims 1 to 5, further comprising a colorant.   The ink composition according to claim 6, wherein the colorant is at least one selected from the group consisting of pigments and oil-soluble dyes.   The ink composition according to claim 1, which is used for inkjet recording.   An image recording step of recording an image on a recording material using the ink composition according to any one of claims 1 to 8, and an image curing step of irradiating and curing the recorded image with an active energy ray An image forming method comprising:   The image forming method according to claim 9, wherein the image recording step performs inkjet recording of the image by discharging the ink composition.   A recorded matter comprising the ink composition according to any one of claims 1 to 8.