JP2007224149A - Ink composition, ink-jet recording method, printed matter, method for producing planographic printing plate and planographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an ink composition that is cured in high sensitivity by irradiation with active radiation, forms a high-quality image, has excellent adhesivity to a medium to be recorded and improved storage stability, to provide an ink-jet recording method using the ink composition, to obtain a printed matter obtained by using the ink composition that has excellent storage stability and is cured in high sensitivity by irradiation with radiation and a planographic printing plate and to provide a method for producing a planographic printing plate. <P>SOLUTION: The radiation-curable ink composition comprises (a) a cationically polymerizable compound, (b) a compound to generate an acid by irradiation with active radiation, (c) a colorant and (d) two or more kinds of amine compounds. The amine compounds are two or more kinds of amine compounds having different solubility parameters. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink composition suitably used for ink jet recording, an ink jet recording method, a printed material using the ink composition, a lithographic printing plate obtained using the ink composition, and a method for producing the lithographic printing plate. Is. Specifically, an ink composition, an ink jet recording method, which can be cured with high sensitivity to radiation irradiation, can form a high quality image, and is suitable for ink jet recording with good storage stability, and The present invention relates to a printed material using the same, a lithographic printing plate obtained using the ink composition, and a method for producing the lithographic printing plate.

  As an image recording method for forming an image on a recording medium such as paper based on an image data signal, there are an electrophotographic method, a sublimation type and a melt type thermal transfer method, an ink jet method and the like. The electrophotographic system requires a process of forming an electrostatic latent image on a photosensitive drum by charging and exposure, and there is a problem that the system becomes complicated and consequently the manufacturing cost becomes high. In addition, although the thermal transfer method is inexpensive, there are problems such as high running costs and waste materials due to the use of ink ribbons. On the other hand, the ink jet system is an inexpensive apparatus and ejects ink only to a required image portion to form an image directly on a recording medium, so that ink can be used efficiently and running cost is low. Furthermore, there is little noise and it is excellent as an image recording method.

  Ink compositions that can be cured by irradiation with radiation such as ultraviolet rays, in particular ink jet recording inks (radiation curable ink jet recording inks), are required to provide sufficiently high sensitivity and high image quality. By achieving high sensitivity, high curability is imparted to radiation, reducing power consumption, extending life by reducing the load on the radiation generator, preventing the generation of low-molecular substances due to insufficient curing, etc. Profits are generated. In addition, when the sensitivity is increased, particularly when an ink composition, in particular, an ink jet recording ink is used as an image portion of a lithographic printing plate, the curing strength of the image portion is increased and high printing durability is obtained. .

  Such a curable ink jet method using radiation, for example, ultraviolet rays has been attracting attention in recent years because it has a relatively low odor, and can be recorded on a recording medium having no quick drying and no ink absorption. An ultraviolet ray curable ink composition for inkjet that is used is disclosed (for example, see Patent Documents 1 to 5). Further, even for a support that is usually difficult to directly record with an ink jet recording method, it is possible to record an image with no blur, high sensitivity, high adhesion to a recording medium, and skin irritation or For the purpose of providing an inkjet recording ink with low sensitization and high safety, a composition containing a polymerizable compound consisting of a specific radical polymerization type acrylate compound group and a coloring material has been proposed ( For example, see Patent Documents 6 and 7.) Although these radical polymerization type inks are excellent in curing speed and can form images without bleeding, they have a problem that adhesion to a recording medium is reduced due to volume shrinkage during curing.

  For this reason, for the purpose of improving the adhesion to the recording medium, a cationic polymerization type ink composition having a small shrinkage rate upon UV curing has been proposed (for example, see Patent Document 8). However, these cationic polymerization type inks are not sufficiently stable at the time of storage due to the reaction based on the acid generated with the passage of time, which has been a major obstacle to practical use. For this reason, as an attempt to improve the storage stability, a technique of adding a basic compound or a thermal base generator has been proposed (for example, see Patent Documents 9 to 11), but the basic compound was generated by exposure. It has been found that a new problem arises that the curing sensitivity of the ink is lowered due to the inhibition of the acid function. For this reason, both storage stability and high sensitivity are desired.

JP-A-63-235382 JP-A-3-216379 Japanese Patent Laid-Open No. 5-214280 Japanese Patent Publication No.6-212256 Japanese Patent Publication No. 6-62905 JP 2003-192943 A JP 2003-192944 A Japanese Patent Laid-Open No. 9-183928 JP 2003-312121 A JP 2003-341217 A JP 2004-91558 A

The object of the present invention made in consideration of the above problems is that it can be cured with high sensitivity by irradiation with actinic radiation, can form a high-quality image, has excellent adhesion to a recording medium, and has storage stability. Is to provide a good ink composition and an ink jet recording method using the ink composition.
Another object of the present invention is to provide a printed matter, a lithographic printing plate, and a method for producing a lithographic printing plate, which are obtained using an ink composition that is excellent in storage stability and can be cured with high sensitivity by irradiation with radiation. It is to provide.

The above object was achieved by the following <1>, <3>, and <5> to <7>. It is shown below together with <2> and <4> which are preferred embodiments.
<1> A radiation-curable ink composition containing (a) a cationically polymerizable compound, (b) a compound that generates an acid upon irradiation with radiation, (c) a colorant, and (d) two or more amine compounds. An ink composition, wherein the amine compound is two or more amine compounds having different SP values,
<2> The ink composition according to <1>, which is for inkjet recording.
<3> An inkjet recording method comprising: (a) a step of discharging an ink composition onto a recording medium; and (b) a step of irradiating the discharged ink composition with actinic radiation to cure the ink composition. An ink jet recording method, wherein the ink composition is the ink composition according to <1> or <2>,
<4> The actinic radiation is irradiated by a light emitting diode that generates ultraviolet rays having an emission peak wavelength in a range of 350 to 420 nm and a maximum illuminance on a recording medium surface of 10 to 2,000 mW / cm ^2. The inkjet recording method according to <3>, which is ultraviolet light,
<5> Printed matter recorded by the inkjet recording method according to <3> or <4>,
<6> (a) a step of discharging the ink composition according to <1> or <2> onto a hydrophilic support; and (b) irradiating the discharged ink composition with actinic radiation to thereby form the ink. A method of producing a lithographic printing plate, comprising: a step of curing the composition to form a hydrophobic image formed by curing the ink composition on the hydrophilic support;
<7> A lithographic printing plate produced by the method for producing a lithographic printing plate according to <6>.

According to the present invention, an ink composition that can be cured with high sensitivity to radiation irradiation, can form a high-quality image, has excellent adhesion to a recording medium, and has good storage stability. In addition, an ink jet recording method using the ink composition can be provided.
Moreover, the printed matter obtained by using the ink composition which is excellent in the storage stability and can be cured with high sensitivity by irradiation with radiation has high image quality and excellent image portion strength. Similarly, by using the ink composition of the present invention, it is possible to produce a lithographic printing plate with high printing durability and high image quality based on digital data.

The ink composition of the present invention (hereinafter, also simply referred to as “ink”) is curable by irradiation with radiation, (a) a cationic polymerizable compound, and (b) a compound that generates an acid upon irradiation with radiation (light (Acid generator), (c) a colorant, and (d) a radiation curable ink composition containing two or more amine compounds, wherein the amine compounds are also referred to as solubility parameters (hereinafter also referred to as “SP values”). And 2) different amine compounds.
The “radiation” referred to in the present invention is not particularly limited as long as it can impart energy capable of generating a starting species in the ink composition by the irradiation, and is broadly α-ray, γ-ray, X-ray. , Ultraviolet rays, visible rays, electron beams, and the like. Among these, from the viewpoints of curing sensitivity and device availability, ultraviolet rays and electron beams are preferable, and ultraviolet rays are particularly preferable. Therefore, the ink composition of the present invention is preferably an ink composition that can be cured by irradiating ultraviolet rays as radiation.
The present invention will be described in detail below.

[(D) Two or more amine compounds]
The ink composition of the present invention contains two or more kinds of amine compounds, and the amine compounds have different SP values. As an amine compound that can be used in the present invention, any combination of amine compounds having different SP values can be used.
By using amine compounds with different SP values, various polymers as polymerizable compounds, photoacid generators (polymerization initiators), colorants, and other additives in the ink during ink storage and ink ejection The compatibility with the compound can be secured in a well-balanced manner, the aging property and curing reactivity of the cationic polymerization type ink can be stably maintained, and good sensitivity and image quality can be maintained.

In general, the solubility parameter (SP value) is known as an index indicating the compatibility and incompatibility between substances. Substances having a small difference in SP value are highly compatible, and a large difference indicates incompatibility. The SP value is a numerical value defined by the square root of the cohesive energy density and represents an intermolecular force. The SP value is one method by which the polarity of a low molecular compound such as a polymer or a solvent and the compatibility between the compounds can be evaluated, and can be estimated by the calculation shown below or by actual measurement.
SP value (δ) = (ΔEv / V) ^1/2
In the above formula, ΔEv represents the molar evaporation energy, and V represents the molar volume.

Further, as the ΔEv and V, ROBERT F.V. Total (ΔEv) and molar volume (v _i ) of molar heat of vaporization (Δe _i ) of atomic groups described in “POLYMER ENGINEERING AND FEBRUARY” (Vol. 14, No. 2, pages 151-153, 1974) by FEDORS (V) can also be used.

In the present invention, the SP value is 10 (cal / cm ³ ) ^1/2 or more and less than 10 (cal / cm ³ ) ^1/2 , preferably 11 (cal / cm ³ ) ^1/2 or more and 9 (cal / cm ³ ) ^1/2 or less, more preferably 12 (cal / cm ³ ) ^1/2 or more and 9 (cal / cm ³ ) ^1/2 or less are used in combination. Although there are unclear points about the details of the effect of using an amine compound having a solubility parameter within the above range, each amine compound is in good agreement with the ink component due to the SP value derived from each component in the ink. It is presumed that an effective action can be expressed with respect to the temporal stability in the cationic polymerization type composition.
Although 2 or more types of amine compounds are used, it is preferable to use 2 to 4 types of amine compounds, more preferably 2 to 3 types of amine compounds, and 2 types of amine compounds to be used. Is particularly preferred. At this time, what is necessary is just to have two or more different solubility parameters.

  The amine compound that can be used in the present invention may be any of primary, secondary, and tertiary amine compounds, and may have two or more amine sites in the molecule. From the viewpoint of suppressing side reactions and discoloration reactions, tertiary amine compounds are preferably used. As a mixing ratio of each of the two or more amine compounds, one amine compound is preferably 10% by weight or more based on the total weight of the amine compound, and one kind of amine compound is used based on the total weight of the amine compound. The amine compound is preferably 90% by weight or less. Within the above range, the characteristics of each amine compound can be exhibited, the ink composition is excellent in storage stability, and a decrease in curing sensitivity can be suppressed.

Specific examples of amine compounds that can be used in the present invention include compounds having SP values of (a-1) to (a-22) shown below of less than 10 (cal / cm ³ ) ^1/2 , (b Although compounds having SP values of (-1) to (b-42) of 10 (cal / cm ³ ) ^1/2 or more are mentioned, the present invention is not limited to these compounds. The SP value calculated based on the Fedors equation is also shown in the specific example.

The content of (d) two or more amine compounds in the ink composition is preferably 0.001 to 10% by weight, more preferably 0.01 to 7% by weight, based on the total solid content of the composition. 0.03 to 5% by weight is more preferable. In the present invention, the solid content in the ink composition is a component obtained by removing volatile components such as a solvent described later from the ink composition.
The ratio of (d) the content of two or more amine compounds to the compound (b) that generates an acid upon irradiation with radiation, which will be described later, is 0.001 to 0.00 in a molar ratio of (d) / (b). 5 is preferable, and 0.005-0.2 is more preferable.

[(A) Cationic polymerizable compound]
The (a) cationic polymerizable compound that can be used in the present invention is not particularly limited as long as it is a compound that initiates a polymerization reaction with an acid generated from a compound that generates an acid upon irradiation with radiation (b) described later and cures. In addition, various known cationic polymerizable monomers known as photo cationic polymerizable monomers can be used. Examples of the cationic polymerizable monomer include JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-310937, and 2001-2001. Examples thereof include epoxy compounds, vinyl ether compounds, oxetane compounds and the like described in each publication such as No. 220526.

Examples of the epoxy compound include aromatic epoxides, alicyclic epoxides, and aliphatic epoxides.
Aromatic epoxides include di- or polyglycidyl ethers produced by the reaction of polyphenols having at least one aromatic nucleus or their alkylene oxide adducts and epichlorohydrin, such as bisphenol A or its alkylene oxides. Examples thereof include di- or polyglycidyl ethers of adducts, di- or polyglycidyl ethers of hydrogenated bisphenol A or its alkylene oxide adducts, and novolak-type epoxy resins. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

As the alicyclic epoxide, cyclohexene obtained by epoxidizing a compound having at least one cycloalkane ring such as cyclohexene ring or cyclopentene ring with a suitable oxidizing agent such as hydrogen peroxide or peracid. Preference is given to oxide or cyclopentene oxide-containing compounds.
Examples of aliphatic epoxides include dihydric 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 1,6. -Diglycidyl ether of alkylene glycol such as diglycidyl ether of hexanediol, polyglycidyl ether of polyhydric alcohol such as di- or triglycidyl ether of glycerin or its alkylene oxide adduct, diglycidyl of polyethylene glycol or its alkylene oxide adduct Diglycidyl of polyalkylene glycol typified by diglycidyl ether of ether, polypropylene glycol or its alkylene oxide adduct Ether and the like. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

The monofunctional and polyfunctional epoxy compounds that can be used in the present invention are exemplified in detail.
Examples of monofunctional epoxy compounds include, for example, 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, 4-vinylcyclohexene oxide etc. are mentioned.

  Examples of polyfunctional epoxy compounds include, for example, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidyl ether, brominated bisphenol F diglycidyl ether, and 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′-epoxycyclohexanecarboxy 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexane-meta-dioxane, bis (3,4-epoxy Hexylmethyl) adipate, 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, ethylene bis (3,4-epoxycyclohexanecarboxylate), dioctyl epoxyhexahydrophthalate, epoxy Di-2-ethylhexyl hexahydrophthalate, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane Liglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ethers, 1,13-tetradecadiene dioxide, limonene dioxide, 1,2,7,8-diepoxyoctane, 1,2,5,6 -Diepoxycyclooctane and the like.

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

  Examples of vinyl ether compounds include ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, butanediol divinyl ether, hexanediol divinyl ether, cyclohexanedimethanol divinyl ether, and trimethylol. Di- or trivinyl ether compounds such as propane trivinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexanedimethanol monovinyl ether, n-pro Vinyl ether, isopropyl vinyl ether, isopropenyl ether -O- propylene carbonate, dodecyl vinyl ether, and a monovinyl ether compounds such as diethylene glycol monovinyl ether.

Below, monofunctional vinyl ether and polyfunctional vinyl ether are illustrated in detail.
Examples of monofunctional vinyl ethers 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 D Ter, 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, and bisphenol F. Divinyl ethers such as alkylene oxide divinyl ether; trimethylolethane trivinyl ether, trimethylolpropane trivinyl ether, ditrimethylolpropane tetravinyl ether, glycerin trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinyl 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 tetravinyl ether, propylene oxide addition Examples thereof include polyfunctional vinyl ethers such as pentaerythritol tetravinyl ether, ethylene oxide-added dipentaerythritol hexavinyl ether, and propylene oxide-added dipentaerythritol hexavinyl ether.
As the vinyl ether compound, a di- or trivinyl ether compound is preferable from the viewpoints of curability, adhesion to a recording medium, surface hardness of the formed image, and the like, and a divinyl ether compound is particularly preferable.

The oxetane compound that can be used in the present invention refers to a compound having at least one oxetane ring, and known oxetane as described in JP-A Nos. 2001-220526, 2001-310937, and 2003-341217. A compound can be arbitrarily selected and used.
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. Therefore, it is preferable.

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

R ^a1 represents 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 a thienyl group. 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, and a butyl group. Preferred examples of the fluoroalkyl group include those in which any hydrogen of these alkyl groups is substituted with a fluorine atom.
R ^a2 is a hydrogen atom, 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, or 2 to 6 carbon atoms. Represents an alkoxycarbonyl group, and an N-alkylcarbamoyl group having 2 to 6 carbon atoms. 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 group and the like. Can be mentioned. As the alkylcarbonyl group, an ethylcarbonyl group, a propylcarbonyl group, a butylcarbonyl group, etc., as an alkoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, a butoxycarbonyl group, etc., as an N-alkylcarbamoyl group, Examples thereof include an ethylcarbamoyl group, a propylcarbamoyl group, a butylcarbamoyl group, and a pentylcarbamoyl group. R ^a2 may have a substituent, and examples of the substituent include an alkyl group of 1 to 6 and a fluorine atom.

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 an alkylene group containing a carbonyl group, a carboxyl group Represents an alkylene group containing, 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, a mercapto group, Represents 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 2,000. 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 following 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.

  As a compound represented by the formula (1), 3-ethyl-3-hydroxymethyloxetane (OXT-101: manufactured by Toagosei Co., Ltd.), 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane (OXT) -212: manufactured by Toagosei Co., Ltd.) and 3-ethyl-3-phenoxymethyloxetane (OXT-211: manufactured by Toagosei Co., Ltd.). Examples of the compound represented by the formula (2) include 1,4-bis [(3-ethyl-3-oxetanylmethoxy) methyl] benzene (OXT-121: manufactured by Toagosei Co., Ltd.). Examples of the compound represented by the formula (3) include bis (3-ethyl-3-oxetanylmethyl) ether (OXT-221: manufactured by Toagosei Co., Ltd.).

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

In the formula (4), R ^a1 has the same ^{meaning as} in the formula (1). In addition, as R ^a9 which is a polyvalent linking group, for example, a branched polyalkylene group having 1 to 12 carbon atoms such as groups represented by the following A to C, a branched poly ( An alkyleneoxy) group or a 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 formula (5) having an oxetane ring in the side chain.

In the formula (5), R ^a1 and R ^a8 have the same ^{meaning as} in the above formula. 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 the above-mentioned JP-A No. 2003-341217, paragraph numbers [0021] to [0084], and the compounds described therein can be suitably used in the present invention. .
Oxetane compounds described in JP 2004-91556 A can also be used in the present invention. It is described in detail in paragraph numbers [0022] to [0058].
Among the oxetane compounds used in the present invention, it is preferable to use a compound having one oxetane ring from the viewpoint of the viscosity and tackiness of the ink composition.

The cationic polymerizable compound (a) that can be used in the present invention may be used alone or in combination of two or more, but from the viewpoint of effectively suppressing shrinkage during ink curing. It is preferable to use a vinyl ether compound in combination with at least one compound selected from oxetane compounds and epoxy compounds.
The content of the cationic polymerizable compound (a) in the ink composition is preferably 10 to 95% by weight, more preferably 30 to 90% by weight, and still more preferably 50 to 50% by weight based on the total solid content of the composition. It is in the range of 85% by weight.

[(B) Compound generating acid upon irradiation]
The ink composition of the present invention contains (b) a compound that generates an acid upon irradiation with radiation (hereinafter also referred to as a “photoacid generator”).
Examples of the photoacid generator that can be used in the ink composition of the present invention include a photoinitiator for photocationic polymerization, a photoinitiator for radical photopolymerization, a photodecolorant for dyes, a photochromic agent, and a microresist. Light (400-200 nm ultraviolet light, far ultraviolet light, particularly preferably g-line, h-line, i-line, KrF excimer laser light), ArF excimer laser light, electron beam, X-ray, molecular beam or ion A compound that generates an acid upon irradiation with a beam or the like can be appropriately selected and used.

  Examples of such a photoacid generator include an onium salt compound such as a diazonium salt, a phosphonium salt, a sulfonium salt, and an iodonium salt that decomposes upon irradiation with radiation, an imide sulfonate, an oxime sulfonate, a diazodisulfone, a disulfone, Examples thereof include sulfonate compounds such as o-nitrobenzyl sulfonate.

  Other compounds (photoacid generators) that generate an acid upon irradiation with actinic rays or radiation used in the present invention include, for example, S.I. I. Schlesinger, Photogr. Sci. Eng. , 18, 387 (1974), T.A. S. Diazonium salts described in Bal etal, Polymer, 21, 423 (1980), ammonium salts described in U.S. Pat. Nos. 4,069,055, 4,069,056, JP-A-3-140140, and the like, D . C. Necker et al., Macromolecules, 17, 2468 (1984), C.I. S. Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988), U.S. Pat. Nos. 4,069,055, 4,069,056, and the like; V. Crivello et al, Macromolecules, 10 (6), 1307 (1977), Chem. & Eng. News, Nov. 28, p31 (1988), European Patent Nos. 104,143, 339,049, 410,201, JP-A-2-150848, JP-A-2-296514 and the like,

  J. et al. V. Crivello et al, Polymer J. et al. 17, 73 (1985), J. MoI. V. Crivello et al. J. et al. Org. Chem. 43, 3055 (1978); R. Watt et al. PolymerSci. , Polymer Chem. Ed. , 22, 1789 (1984), J. Am. V. Crivello et al., Polymer Bull. 14, 279 (1985), J. Am. V. Crivello et al, Macromolecules, 14 (5), 1141 (1981), J. MoI. V. Crivello et al. PolymerSci. , Polymer Chem. Ed. 17, 2877 (1979), European Patent Nos. 370,693, 161,811, 410,201, 339,049, 233,567, 297,443, and 297,442. U.S. Pat.Nos. 3,902,114, 4,933,377, 4,760,013, 4,734,444, 2,833,827, German Patent 2, Nos. 904, 626, 3,604, 580, 3,604, 581, JP-A-7-28237, 8-27102 and the like,

  J. et al. V. Crivello et al., Macromolecules, 10 (6), 1307 (1977), J. MoI. V. Crivello et al. PolymerSci. , Polymer Chem. Ed. , 17, 1047 (1979), etc., selenonium salts, C.I. S. Wen et al, Teh, Proc. Conf. Rad. Curing ASIA, p478 Tokyo, Oct (1988) and other onium salts such as arsonium salts, US Pat. No. 3,905,815, Japanese Examined Patent Publication No. 46-4605, Japanese Unexamined Patent Publication No. 48-36281, Japanese Unexamined Patent Publication No. 55-55. -32070, JP-A-60-239736, JP-A-61-169835, JP-A-61-169837, JP-A-62-58241, JP-A-62-212401, JP-A-63-70243 , Organic halogen compounds described in JP-A-63-298339 and the like; Meier et al, J.A. Rad. Curing, 13 (4), 26 (1986), T.A. P. Gill et al, Inorg. Chem. , 19, 3007 (1980), D.M. Astruc, Acc. Chem. Res. , 19 (12), 377 (1986), and organometallic / organic halides described in JP-A-2-161445, etc.

  S. Hayase et al. Polymer Sci. 25, 753 (1987), E.I. Reichmanis et al. Polymer Sci. , Polymer Chem. Ed. , 23, 1 (1985), Q.M. Q. Zhu etal, J. et al. Photochem. 36, 85, 39, 317 (1987), B.R. Amit etal, Tetrahedron Lett. , (24) 2205 (1973), D.M. H. R. Barton et al. Chem. Soc. , 3571 (1965), p. M.M. Collins et al, J.A. Chem. Soc. Perkin I, 1695 (1975), M .; Rudinstein et al., Tetrahedron Lett. , (17), 1445 (1975), J. MoI. W. Walker et al. Am. Chem. Soc. 110, 7170 (1988), S.A. C. Busman et al. Imaging Technol. 11 (4), 191 (1985), H. et al. M.M. Houlihan et al, Macromolecules, 21, 2001 (1988), p. M.M. Collins et al. Chem. Soc. , Chem. Commun. 532 (1972), S.A. Hayase et al., Macromolecules, 18, 1799 (1985), E.I. Reichmanis et al. Electrochem. Soc. , Solid State Sci. Technol. , 130 (6), F.M. M.M. Houlihan et al, Macromolecules, 21, 2001 (1988), European Patent Nos. 0,290,750, 046,083, 156,535, 271,851, 0,388,343, US Patents No. 3,901,710, 4,181,531, JP-A-60-198538, JP-A-53-133022 and the like, a photoacid generator having an O-nitrobenzyl type protecting group,

  M.M. TUNOOKA et al, Polymer Preprints Japan, 35 (8), G.M. Berner et al. Rad. Curing, 13 (4), W.M. J. et al. Mijs et al, Coating Technol. , 55 (697), 45 (1983), Akzo, H .; Adachi et al, Polymer Preprints, Japan, 37 (3), European Patent Nos. 0,199,672, 84,515, 044,115, 618,564, 0,101,122, Represented by the iminosulfonates described in U.S. Pat. Nos. 4,371,605, 4,431,774, JP-A 64-18143, JP-A-2-245756, JP-A-3-140109, etc. Compounds that generate sulfonic acid upon photolysis, disulfone compounds described in JP-A Nos. 61-166544 and 2-71270, JP-A-3-103854, JP-A-3-103856, and JP-A-210960 And diazoketosulfone and diazodisulfone compounds described in the above.

  Further, a group in which an acid is generated by these lights, or a compound in which a compound is introduced into the main chain or side chain of the polymer, for example, M.I. E. Woodhouse et al., J. MoI. Am. Chem. Soc. 104, 5586 (1982), S .; P. Pappas et al. Imaging Sci. , 30 (5), 218 (1986), S.A. Kondo et al, Makromol. Chem. , Rapid Commun. , 9, 625 (1988), Y. et al. Yamada et al, Makromol. Chem. 152, 153, 163 (1972), J. Am. V. Crivello et al, J.A. PolymerSci. , Polymer Chem. Ed. , 17, 3845 (1979), U.S. Pat. No. 3,849,137, German Patent 3,914,407, JP-A 63-26653, JP-A 55-164824, JP-A 62- 69263, JP-A-63-146038, JP-A-63-163452, JP-A-62-153853, JP-A-63-146029, and the like can be used. For example, diazonium salts, ammonium salts, phosphonium salts, iodonium salts, sulfonium salts, selenonium salts, onium salts such as arsonium salts, organic halogen compounds, organic metal / organic halides, photoacid generators having o-nitrobenzyl type protecting groups Examples thereof include a compound capable of generating a sulfonic acid by photolysis represented by an agent, iminosulfonate, and the like, a disulfone compound, a diazoketosulfone, and a diazodisulfone compound.

  Furthermore, V. N. R. Pillai, Synthesis, (1), 1 (1980), A.M. Abad et al., Tetrahedron Lett. , (47) 4555 (1971), D.M. H. R. Barton et al, J.A. Chem. Soc. , (C), 329 (1970), U.S. Pat. No. 3,779,778, European Patent No. 126,712, and the like, compounds that generate an acid by light can also be used.

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

In the 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 preferred are perfluoroalkyl groups 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 and Rc ^{3 to} Rc ⁵ is most preferably an alkyl group substituted at the 1-position with a fluorine atom or a fluoroalkyl group, or 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 preferably 1 to 30, more preferably 1 to 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 Formula (b1) may be sufficient. For example, at least one of R ²⁰¹ to R ²⁰³ of a compound represented by the formula (b1) is at least one directly with R ²⁰¹ to R ²⁰³ of another compound represented by formula (b1), or a linking group It may be a compound having a structure bonded via

  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.

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

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. Substituents, of the three R ²⁰¹ to R ^203, may be substituted on any one, or may be substituted on all of 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 is preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms.
R ²⁰¹ to R ²⁰³ each independently, preferably an alkyl group, a cycloalkyl group, an allyl group, a vinyl group, more preferably a linear, branched or cyclic 2-oxoalkyl group, an alkoxycarbonylmethyl group, particularly preferably Is a linear, branched 2-oxoalkyl group.

The alkyl group as R ²⁰¹ to R ²⁰³ may be linear, it 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.

Linear R ²⁰¹ to R ^203, branched, or cyclic 2-oxoalkyl group, preferably, may be mentioned 2-position group having> C = O at the above-described alkyl 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 formula (b1-3) and is a compound having a phenacylsulfonium salt structure.

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

The alkyl group as R ^{1c to} R ^7c may be either linear or branched, and is preferably a linear and branched alkyl group having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms. (For example, a methyl group, an ethyl group, a linear or branched propyl group, a linear or branched butyl group, a 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. This is preferable because solvent solubility is further improved and generation of particles is suppressed during storage.

^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.

Formula (b2), in (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 non-nucleophilic anion as 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, it 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.
R ²⁰⁴ and R ²⁰⁵ , R ²⁰⁶ and R ²⁰⁷ may combine 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 group R ²⁰⁴ and R ^205, R ²⁰⁶ and R ²⁰⁷ is formed by bonding, there can be mentioned an alkylene group (e.g., butylene, pentylene).
In addition, the compound which has two or more structures represented by Formula (b2) or (b3) may be sufficient. For example, R ²⁰⁴ or R ²⁰⁵ of the compound represented by the formula (b2) is bonded to R ²⁰⁴ or R ²⁰⁵ in the other compound represented by the formula (b2) directly or via a linking group. It may be a compound.

  Examples of the compound that generates an acid upon irradiation with actinic rays or radiation that may be used further include compounds represented by the following formulas (b4), (b5), and (b6).

In 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, an aryl group or a cyano group.
A represents an alkylene group, an alkenylene group or an arylene group.
Ar ³ and Ar ⁴ , R ^{206 to} R ^{208 and} A may have a substituent, for example, an alkyl group (for example, 1 to 15 carbon atoms), a cycloalkyl group (for example, 3 to 15 carbon atoms), aryl Examples include a group (for example, having 6 to 15 carbon atoms), an alkoxy group (for example, having 1 to 15 carbon atoms), a halogen atom, a hydroxyl group, and a phenylthio group.
In addition, the compound which has two or more structures represented by Formula (b4)-(b6) may be sufficient. For example, the formula (b6) at least one of R ²⁰⁶ to R ²⁰⁸ of a compound represented are in direct at least one of R ²⁰⁶ to R ²⁰⁸ in another compound represented by Formula (b6), or the linking group It may be a compound having a structure bonded via

Preferable examples of the photoacid generator include compounds represented by formulas (b1) to (b3).
Preferred compound examples ((b-1) to (b-96)) of (b) photoacid generator that can be used in the present invention are listed below, but the present invention is not limited thereto.

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, paragraph numbers [0037] to [0063] can also be suitably used in the present invention.

(B) A photo-acid generator can be used individually by 1 type or in combination of 2 or more types.
The content of the (b) photoacid generator in the ink composition is preferably 0.1 to 20% by weight, more preferably 0.5 to 10% by weight, and still more preferably, in terms of the total solid content of the ink composition. Is 1-7% by weight.

[(C) Colorant]
The ink composition of the present invention contains (c) a colorant.
The colorant that can be used in the present invention is not particularly limited, but pigments and oil-soluble dyes that are excellent in weather resistance and excellent in color reproducibility are preferable, and are selected from any known colorant such as a soluble dye. Can be used. The colorant that can be suitably used in the ink composition of the present invention or the ink composition for inkjet recording preferably does not function as a polymerization inhibitor in a polymerization reaction that is a curing reaction. This is because the sensitivity of the curing reaction by actinic radiation is not reduced.

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

  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 copolymer, a modified polyacrylate, an aliphatic Examples thereof include polyvalent carboxylic acids, naphthalene sulfonic acid formalin condensates, polyoxyethylene alkyl phosphate esters, and pigment derivatives. 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 weight with respect to 100 parts by weight of the pigment.

  In the ink composition, as a dispersion medium for various components such as pigments, a solvent may be added, or the solvent-free low molecular weight component (a) cationic polymerizable compound may be used as a dispersion medium. However, the ink composition of the present invention is a radiation curable ink, and is preferably solventless in order to cure the ink after it 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, as the dispersion medium, (a) a cationically polymerizable compound is used, and among them, it is preferable to select a cationically polymerizable monomer having the lowest viscosity in terms of dispersion suitability and handling properties of the ink composition. .

The average particle diameter of the pigment is preferably 0.02 to 0.4 μm, more preferably 0.02 to 0.1 μm, and more preferably 0.02 to 0.07 μm.
Selection of pigments, dispersants, and dispersion media, dispersion conditions, and filtration conditions are set so that the average particle diameter of the pigment particles falls within the above preferred range. 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〕
The dye that can be 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. Accordingly, so-called water-insoluble oil-soluble dyes are preferably used.

The dye that can be used in the present invention preferably has an oil-solubilizing group introduced into the dye mother nucleus described above 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 paragraphs [0060] to [0071] of JP-A-250483. The oil-soluble dye of the general formula (Y-I) described in the publication may be used not only for yellow but also for inks of any color such as black ink and red ink.

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

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

  These colorants are preferably added in an amount of 1 to 20% by weight in terms of solid content in the ink composition, and more preferably 2 to 10% by weight.

[Other ingredients]
The various additives that can be used in the ink composition of the present invention as necessary are described below.

[Ultraviolet absorber]
In the present invention, an ultraviolet absorber can be used from the viewpoint of improving the weather resistance of the obtained 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. 5-194843, 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 is appropriately selected according to the purpose, but generally it is preferably 0.5 to 15% by weight in terms of solid content.

[Sensitizer]
If necessary, a sensitizer may be added to the ink composition of the present invention for the purpose of improving the acid generation efficiency of the photoacid generator and increasing the photosensitive wavelength. Any sensitizer may be used as long as the photoacid generator is sensitized by an electron transfer mechanism or an energy transfer mechanism. Preferably, aromatic polycondensed compounds such as anthracene, 9,10-dialkoxyanthracene, pyrene and perylene, aromatic ketone compounds such as acetophenone, benzophenone, thioxanthone and Michlerketone, and heterocyclic compounds such as phenothiazine and N-aryloxazolidinone Is mentioned. Although the addition amount is appropriately selected according to the purpose, it is preferably used in an amount of 0.01 to 1 mol%, more preferably 0.1 to 0.5 mol% with respect to (b) the photoacid generator.

〔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, 62-262547, 63-113536, 63-163351, JP-A-2-262654, JP-A-2-71262, As 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, etc. Things can be mentioned.
Although the addition amount is appropriately selected according to the purpose, it is preferably 0.1 to 8% by weight in terms of solid content.

[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. .
Although the addition amount is appropriately selected according to the purpose, it is preferably 0.1 to 8% by weight in terms of solid content.

[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 the range that does not cause the problem of solvent resistance and VOC, and the amount is preferably 0.1 to 5% by weight, more preferably 0.1 to 3% by weight based on the whole ink composition. % 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 dialkylsulfosuccinates, alkylnaphthalenesulfonates, 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 instead 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 a tackifier, specifically, a high molecular weight adhesive polymer (for example, (meth) acrylic acid and an alkyl group having 1 to 20 carbon atoms) described in JP-A-2001-49200, 5-6p. An ester with an alcohol having, an ester of (meth) acrylic acid and an alicyclic alcohol having 3 to 14 carbon atoms, a copolymer comprising an ester of (meth) acrylic acid and an aromatic alcohol having 6 to 14 carbon atoms) Or 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 at a temperature at the time of ejection (for example, 25 to 80 ° C., preferably 25 to 50 ° C.) in consideration of ejection properties. The pressure is preferably 7 to 15 mPa · s, and is preferably determined by adjusting the composition ratio as appropriate so as to be in the above range. The ink viscosity at 25 to 30 ° C. is preferably 8 to 300 mPa · s, more preferably 10 to 100 mPa · s. It is preferable that the composition ratio of the ink composition of the present invention is appropriately adjusted so that the viscosity is in the above range. When the viscosity at room temperature is set high, ink penetration into the recording medium can be avoided even when a porous recording medium is used, and uncured monomers can be reduced and odors can be reduced. Furthermore, ink bleeding at the time of ink droplet landing can be suppressed, and as a result, the image quality is improved. When the viscosity at room temperature is set low, heating during ink ejection is unnecessary, or the heating temperature can be set to a relatively low temperature, so the load on the inkjet device is reduced and the range of usable inkjet heads is widened Have

  The surface tension of the ink composition of the present invention is preferably 20 to 30 mN / m, more preferably 23 to 28 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.

The ink composition of the present invention thus prepared is suitably used as an ink for inkjet recording. When used as an ink for ink jet recording, the ink composition is ejected onto a recording medium by an ink jet printer, and then the ejected ink composition is irradiated with radiation and cured to perform recording.
In the printed 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. Therefore, in addition to image formation with ink, for example, an ink receiving layer (image image of a lithographic printing plate) Part), and can be used for various purposes.

[Inkjet recording method and inkjet recording apparatus]
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.

The inkjet recording method of the present invention includes (a) a step of ejecting an ink composition onto a recording medium, and (b) a step of curing the ink composition by irradiating the ejected ink composition with radiation. An ink jet recording method using the ink composition of the present invention.
The printed matter of the present invention is a printed matter recorded by the inkjet recording method.
In the ink jet recording method, it is preferable that the ink composition is heated to 40 to 80 ° C. and the viscosity of the ink composition is lowered to 5 to 10 mPa · s and then discharged. 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 the droplet discharge speed as it is, which causes image quality deterioration. Therefore, it is necessary to keep the temperature of the ink composition during printing as constant as possible. 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 an intermediate tank is present) 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 thermal energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

Next, radiation 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.
Here, α-rays, γ-rays, electron beams, X-rays, ultraviolet rays, visible light, infrared light, or the like can be used as the radiation used. The peak wavelength of the actinic radiation is, for example, from 200 to 600 nm, preferably from 300 to 450 nm, more preferably from 350 to 450 nm, although it depends on the absorption characteristics of the sensitizing dye. In the present invention, the polymerization initiation system has sufficient sensitivity even with a low-power active radiation. Thus, the output of the actinic radiation is, for example, 2,000 mJ / cm ² or less, preferably, 10 to 2,000 mJ / cm ^2, more preferably, 20 to 1,000 mJ / cm ^2, more preferably, 50 to 800 mJ An irradiation energy of / cm ² is appropriate. The active radiation, the illumination intensity on the exposed surface is, for example, 10 to 2,000 mW / cm ^2, preferably, it is suitable to be irradiated at 20 to 1,000 mW / cm ^2.

  In the present invention, the ink composition is heated to a constant temperature, and the time from landing to irradiation is desirably 0.01 to 0.5 seconds, preferably 0.01 to 0.3 seconds, and more preferably Preferably, radiation is applied 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. Also, since the ink composition can be exposed to a porous recording medium before it penetrates deeper than the light source reaches, unreacted monomer remains, 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 8 to 500 mPa · 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 a color with low brightness. When inks with low lightness are stacked, it is difficult for the irradiation rays to reach the lower ink, and inhibition of curing sensitivity, increase of residual monomers, generation of odor, and deterioration of adhesion tend 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.
Examples of the ink jet recording apparatus that can be used in the present invention include an ink supply system, a temperature sensor, and an actinic radiation source.
The ink supply system includes, for example, an original tank containing the ink composition of the present invention, a supply pipe, an ink supply tank immediately before the inkjet head, a filter, and a piezo-type inkjet head. The piezo-type inkjet head has a multi-size dot of 1 to 100 pl, preferably 8 to 30 pl, for example, 320 × 320 to 4,000 × 4,000 dpi, preferably 400 × 400 to 1,600 × 1,600 dpi. More preferably, it can be driven so as to discharge at a resolution of 720 × 720 dpi. In the present invention, dpi represents the number of dots per 2.54 cm.
As described above, since it is desirable that the radiation curable ink has a constant temperature for the ejected ink, heat insulation and heating can be performed from the ink supply tank to the inkjet head portion. The temperature control method is not particularly limited, but for example, it is preferable to provide a plurality of temperature sensors at each piping site and perform heating control according to the ink flow rate and the environmental temperature. The temperature sensor can be provided near the ink supply tank and the nozzle of the inkjet head. 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 thermal energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.
As the active radiation source, a mercury lamp, a gas / solid laser or the like is mainly used, and a mercury lamp and a metal halide lamp are widely known as the ultraviolet light curable ink jet. However, from the viewpoint of environmental protection, mercury-free is strongly desired, and replacement with a GaN-based semiconductor ultraviolet light-emitting device is very useful industrially and environmentally. Furthermore, LED (UV-LED) and LD (UV-LD) are small, have a long life, have high efficiency, and are low in cost, and are expected as light sources for photocurable ink jets.
Further, a light emitting diode (LED) and a laser diode (LD) can be used as the active radiation source. In particular, when an ultraviolet light source is required, an ultraviolet LED and an ultraviolet LD can be used. For example, Nichia Corporation has introduced a purple LED whose main emission spectrum has a wavelength between 365 nm and 420 nm. When even shorter wavelengths are required, US Pat. No. 6,084,250 discloses an LED that can emit actinic radiation centered between 300 nm and 370 nm. Other ultraviolet LEDs are also available and can emit radiation in different ultraviolet bands. The actinic radiation source particularly preferred in the present invention is a UV-LED, particularly preferably a UV-LED having a peak wavelength at 350 to 420 nm.
It is preferable that maximum illumination intensity of the LED on a recording medium is 10 to 2,000 mW / cm ^2, more preferably 20 to 1,000 mW / cm ^2, particularly preferably 50 to 800 mW / cm ² .

[Recording medium]
The recording medium to which the ink composition of the present invention can be applied is not particularly limited, and various non-absorbing resin materials used for ordinary non-coated paper, coated paper, and so on, so-called soft packaging, or the like. A resin film formed into a film can be used, and examples of the various plastic films include PET film, OPS film, OPP film, ONy film, PVC film, PE film, and TAC film. In addition, examples of the plastic that can be used as the recording medium material include polycarbonate, acrylic resin, ABS, polyacetal, PVA, and rubbers. Metals and glasses can also be used as the recording medium.
The ink composition of the present invention has little heat shrinkage at the time of curing and excellent adhesion to the substrate (recording medium), so that the film curls and deforms due to the ink shrinkage and heat generation during the curing reaction. Films that tend to occur, such as PET film, OPS film, OPP film, ONy film, PVC film, and the like that can be shrunk by heat, have an advantage that a high-definition image can be formed.

[Lithographic printing plate]
A preferable application example of the ink composition of the present invention is use in a lithographic printing plate.
The method for producing a lithographic printing plate of the present invention comprises (a) a step of discharging the ink composition of the present invention onto a hydrophilic support, and (b) irradiating the discharged ink composition with radiation, The method includes a step of forming a hydrophobic image formed by curing the ink composition on the hydrophilic support by curing the ink composition.
The lithographic printing plate of the present invention is a lithographic printing plate produced by the lithographic printing plate production method.
After discharging the ink composition of the present invention onto a hydrophilic support using an ink jet recording apparatus or the like, the ink is cured by irradiating with radiation to form a hydrophobic image on the surface of the hydrophilic support. An image-like hydrophobic ink-receiving area is formed. When the ink and the aqueous component are supplied here, the aqueous component is held in the exposed region of the hydrophilic support, the ink is held in the hydrophobic image, and the printing process can be performed as it is.
Since the ink composition of the present invention exhibits excellent curability upon irradiation with radiation, the lithographic printing plate of the present invention to which the ink composition is applied has an image portion having excellent printing durability. In addition, an inkjet recording apparatus can be used to form an image portion, and a high-definition lithographic printing plate image portion can be formed directly from digital data.
The ink composition of the present invention described above may be applied as it is to the ink composition used for the production of a lithographic printing plate.

[Support]
The support preferably used for preparing the planographic printing plate of the present invention will be described.
The support used for the lithographic printing plate of the present invention is not particularly limited as long as it is a dimensionally stable plate-like support. If the material constituting the support has surface hydrophilicity, it may be used as it is, or the surface of the plate-like material constituting the support may be subjected to a hydrophilic treatment.
Examples of the material constituting the support include paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), and plastic film (eg, diacetic acid). Cellulose, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), paper or plastic film laminated or vapor-deposited with the above metals Etc. A preferable support includes a polyester film and an aluminum plate. Among these, an aluminum plate that has good dimensional stability and is relatively inexpensive is preferable.

  The aluminum plate is a pure aluminum plate, an alloy plate containing aluminum as a main component and containing a trace amount of foreign elements, or a plastic laminated on a thin film of aluminum or an aluminum alloy. Examples of the foreign element contained in the aluminum alloy include silicon, iron, manganese, copper, magnesium, chromium, zinc, bismuth, nickel, and titanium. The content of foreign elements in the alloy is preferably 10% by weight or less. In the present invention, a pure aluminum plate is preferable, but completely pure aluminum is difficult to manufacture in terms of refining technology, and therefore may contain a slightly different element. The composition of the aluminum plate is not specified, and a publicly known material can be used as appropriate.

  The thickness of the support is preferably from 0.1 to 0.6 mm, more preferably from 0.15 to 0.4 mm.

  Prior to using the aluminum plate, it is preferable to perform a surface treatment such as roughening treatment or anodizing treatment. By the surface treatment, it is easy to improve hydrophilicity and secure adhesion between the image recording layer and the support. Prior to roughening the aluminum plate, a degreasing treatment with a surfactant, an organic solvent, an alkaline aqueous solution or the like for removing rolling oil on the surface is performed as desired.

The surface roughening treatment of the aluminum plate is performed by various methods. For example, mechanical surface roughening treatment, electrochemical surface roughening treatment (surface roughening treatment for dissolving the surface electrochemically), chemical treatment, etc. Surface roughening treatment (roughening treatment that chemically selectively dissolves the surface).
As a method for the mechanical surface roughening treatment, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be used. Also, a transfer method in which the uneven shape is transferred with a roll provided with unevenness in the aluminum rolling step may be used.
Examples of the electrochemical surface roughening treatment include a method in which an alternating current or a direct current is used in an electrolytic solution containing an acid such as hydrochloric acid or nitric acid. Another example is a method using a mixed acid as described in JP-A-54-63902.

  The surface-roughened aluminum plate is subjected to an alkali etching treatment using an aqueous solution of potassium hydroxide, sodium hydroxide or the like, if necessary, further neutralized, and if desired, wear resistant. In order to increase the anodic oxidation treatment.

As the electrolyte used for the anodizing treatment of the aluminum plate, various electrolytes that form a porous oxide film can be used. In general, sulfuric acid, hydrochloric acid, oxalic acid, chromic acid or a mixed acid thereof is used. The concentration of these electrolytes is appropriately determined depending on the type of electrolyte.
The conditions for anodizing treatment vary depending on the electrolyte used and cannot be specified in general. In general, however, the electrolyte concentration is 1 to 80% by weight solution, the liquid temperature is 5 to 70 ° C., and the current density is 5 to 60 A / day. dm ² , voltage 1 to 100 V, and electrolysis time 10 seconds to 5 minutes are preferable. The amount of the anodized film formed is preferably from 1.0 to 5.0 g / m ^2, and more preferably 1.5 to 4.0 g / m ^2. Within this range, good printing durability and good scratch resistance of the non-image area of the planographic printing plate can be obtained, which is preferable.

  As a support used in the present invention, a substrate that has been surface-treated as described above and that has an anodized film may be used as it is, but it has excellent adhesion to the upper layer, hydrophilicity, resistance to contamination, heat insulation, etc. For further improvement, an aqueous solution containing a hydrophilic compound and a micropore enlargement treatment or sealing treatment of an anodized film described in JP-A Nos. 2001-253181 and 2001-322365, if necessary It is possible to appropriately select and perform surface hydrophilization treatment that is immersed in the substrate. Of course, these enlargement processing and sealing processing are not limited to those described above, and any conventionally known method can be performed.

[Sealing treatment]
Sealing treatment includes vapor sealing, single treatment with zirconic fluoride, treatment with an aqueous solution containing an inorganic fluorine compound such as treatment with sodium fluoride, vapor sealing with addition of lithium chloride, sealing with hot water. Hole processing is also possible.
Of these, sealing treatment with an aqueous solution containing an inorganic fluorine compound, sealing treatment with water vapor, and sealing treatment with hot water are preferable.

[Hydrophilic treatment]
Examples of the hydrophilization treatment used in the present invention include US Pat. Nos. 2,714,066, 3,181,461, 3,280,734, and 3,902,734. There is an alkali metal silicate method as described in the book. In this method, the support is immersed in an aqueous solution such as sodium silicate or electrolytically treated. In addition, the treatment with potassium zirconate fluoride described in JP-B 36-22063, U.S. Pat. Nos. 3,276,868, 4,153,461 and 4,689, And a method of treating with polyvinylphosphonic acid as described in each specification of No.272.

  The support that can be used in the present invention preferably has a center line average roughness of 0.10 to 1.2 μm. Within this range, good adhesion to the image recording layer, good printing durability and good stain resistance can be obtained.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to these examples.

[Methods for measuring physical properties of amine compounds]
The solubility parameter of the amine compound used is a value calculated by the Fedors method.

[Example 1]
(Preparation of pigment dispersion)
According to the method described below, yellow, magenta, cyan and black pigment dispersions 1 were prepared. The dispersion conditions are appropriately adjusted using a known dispersion device so that the average particle diameter of each pigment particle is in the range of 0.2 to 0.3 μm, and then the filter is heated under a filter. Prepared by filtration.
(Yellow pigment dispersion 1)
・ C. I. Pigment Yellow 13 20 parts by weight / polymer dispersing agent (Solsperse series manufactured by Zeneca) 20 parts by weight / diethylene glycol divinyl ether (manufactured by BASF) 60 parts by weight (magenta pigment dispersion 1)
・ C. I. Pigment Red 57: 1 20 parts by weight / polymer dispersing agent (Solsperse series manufactured by Zeneca) 20 parts by weight / diethylene glycol divinyl ether (manufactured by BASF) 60 parts by weight (cyan pigment dispersion 1)
・ C. I. Pigment Blue 15: 3 20 parts by weight / polymer dispersing agent (Solsperse series manufactured by Zeneca) 20 parts by weight / diethylene glycol divinyl ether (manufactured by BASF) 60 parts by weight (black pigment dispersion 1)
・ C. I. 20 parts by weight of Pigment Black 7 / polymer dispersant (Solsperse series manufactured by Zeneca) 20 parts by weight / 60 parts by weight of diethylene glycol divinyl ether (manufactured by BASF)

[Preparation of ink]
The following components were mixed and filtered through a filter to obtain ink 1 of each color.
(Yellow ink 1)
-(A) Cationic polymerizable compound Celoxide 2021 (epoxy compound: manufactured by Daicel UCB) 35 parts by weight OXT-221 (Oxetane compound: manufactured by Toagosei Co., Ltd.) 55 parts by weight-(b) Photoacid generator Compound Example (b-27) / (b-32) = 1/2 5 parts by weight (c) Colorant (pigment dispersion)
Yellow Pigment Dispersion 1 5 parts by weight. (D) Two or more amine compounds Amine compound examples (a-3: SP value = 8.0) 0.03 parts by weight Amine compound examples (b-20: SP value = 14) .6) 0.03 parts by weight

(Magenta ink 1)
-(A) Cationic polymerizable compound Celoxide 2021 (epoxy compound: manufactured by Daicel UCB) 35 parts by weight OXT-221 (Oxetane compound: manufactured by Toagosei Co., Ltd.) 55 parts by weight-(b) Photoacid generator Compound Example (b-3) 5 parts by weight (c) Colorant (pigment dispersion)
Magenta Pigment Dispersion 1 5 parts by weight. (D) Two or more kinds of amine compounds Amine compound examples (a-3: SP value = 8.0) 0.03 parts by weight Amine compound examples (b-20: SP value = 14) .6) 0.03 parts by weight

(Cyan ink 1)
-(A) Cationic polymerizable compound Celoxide 2021 (epoxy compound: manufactured by Daicel UCB) 35 parts by weight OXT-221 (Oxetane compound: manufactured by Toagosei Co., Ltd.) 55 parts by weight-(b) Photoacid generator Compound Example (b-75) 5 parts by weight (c) Colorant (pigment dispersion)
Cyan Pigment Dispersion 1 5 parts by weight. (D) Two or more types of amine compounds Amine compound examples (a-3: SP value = 8.0) 0.03 parts by weight Amine compound examples (b-20: SP value = 14) .6) 0.03 parts by weight

(Black ink 1)
-(A) Cationic polymerizable compound Celoxide 2021 (epoxy compound: manufactured by Daicel UCB) 35 parts by weight OXT-221 (Oxetane compound: manufactured by Toagosei Co., Ltd.) 55 parts by weight-(b) Photoacid generator Compound Example (b-10) 5 parts by weight / (c) Colorant (pigment dispersion)
Black pigment dispersion 1 5 parts by weight (d) Two or more amine compounds Examples of amine compounds (a-3: SP value = 8.0) 0.03 parts by weight Examples of amine compounds (b-20: SP value = 14) .6) 0.03 part by weight / sensitizer 9,10-dimethoxyanthracene 0.5 part by weight

[Inkjet image recording] (Evaluation of multicolor images)
Next, recording on a recording medium was performed using a commercially available inkjet recording apparatus having a piezoelectric inkjet nozzle. The ink supply system was composed of an original tank, supply piping, an ink supply tank immediately before the inkjet head, a filter, and a piezo-type inkjet head, and heat insulation and heating were performed from the ink supply tank to the inkjet head portion. Temperature sensors were provided near the ink supply tank and the nozzles of the inkjet head, respectively, and temperature control was performed so that the nozzle portions were always 40 ° C. ± 2 ° C. The piezo-type inkjet head was driven so that 8 to 30 pl multi-size dots could be ejected at a resolution of 720 × 720 dpi. After landing, UV-A light is condensed to an exposure surface illuminance of 100 mW / cm ² , and the exposure system, main scanning speed and ejection frequency are adjusted so that irradiation starts 0.1 seconds after ink landing on the recording medium. . Further, the exposure time was variable, and exposure energy was irradiated. In the present invention, dpi represents the number of dots per 2.54 cm.

Each color ink prepared above was ejected in the order of black → cyan → magenta → yellow at an ambient temperature of 25 ° C. and irradiated with ultraviolet rays for each color. In order to eliminate tackiness by palpation, the exposure was performed with a total exposure energy per color of 300 mJ / cm ² as the energy for complete curing. As recording media, each color image was recorded on a grained aluminum support, a transparent biaxially stretched polypropylene film having a printability, a soft vinyl chloride sheet, cast coated paper, and commercially available recycled paper. However, in both cases, a high-resolution image without dot bleeding was obtained. Furthermore, even on high-quality paper, the ink was sufficiently cured without causing the ink to turn around, and there was almost no odor due to unreacted monomers. Further, the ink recorded on the film had sufficient flexibility, and the ink did not crack even when it was bent, and there was no problem in the adhesion test by cellophane tape peeling.

[Examples 2 to 8, Comparative Examples 1 and 2]
[Preparation of ink]
(Magenta ink 2-10)
-(A) 90 parts by weight of a cationic polymerizable compound-(b) 5 parts by weight of a photoacid generator-(c) 5 parts by weight of a colorant (the magenta pigment dispersion 1)-(d) two or more amine compounds, respectively 0.03 part by weight per compound, 0.5 part by weight of sensitizer as required Each of the compounds used in Examples 2 to 8 (magenta inks 2 to 8) and Comparative Examples 1 and 2 (magenta inks 9 and 10) The component compounds are shown in Table 1 below. The SP value of the amine compound used is also shown in Table 1 below.

The details of the cationically polymerizable compounds and sensitizers listed in Table 1 below are as follows.
Cationic polymerizable compound (1): Celoxide 2021 (epoxy: manufactured by Daicel UCB Co., Ltd.) / OXT-221 (Oxetane: manufactured by Toagosei Co., Ltd.) = 35/55 mixture Cationic polymerizable compound (2): Celoxide 3000 ( Epoxy: Daicel UCB Co., Ltd./OXT-211 (Oxetane: Toagosei Co., Ltd.) = 50/40 mixture Cationic polymerizable compound (3): Bisphenol A-diglycidyl ether / OXT-221 (Oxetane: Tojo) Synthetic Co., Ltd.) = 40/50 mixture Cationic polymerizable compound (4): Celoxide 2021 (Epoxy: Daicel UCB Co., Ltd.) / OXT-101 (Oxetane: Toagosei Co., Ltd.) = 55/35 mixture Sensitizer (5): 9,10-dimethoxyanthracene Sensitizer (6): Pyrene In Comparative Example 2, Was added octylamine (SP value = 8.6).

[Inkjet image recording] (single color image evaluation)
Using the magenta inks 2 to 10 prepared as described above, magenta images were produced in the same manner as in the method described in Example 1.
Next, for each formed image, the sensitivity required for curing, penetrability in commercially available recycled paper, ink bleed on a grained aluminum support, adhesion, printing durability, ink in accordance with the method described below Storage stability, ejection stability, and print image quality were evaluated.

(Measurement of curing sensitivity)
The amount of exposure energy (mJ / cm ² ) at which the sticky feeling disappears on the image surface after ultraviolet irradiation was defined as the curing sensitivity. The smaller the value, the higher the sensitivity.

(Evaluation of ink storage stability)
The prepared ink was stored at 75% RH and 60 ° C. for 3 days, then the ink viscosity at the ejection temperature was measured, and the increase in the ink viscosity was expressed as the viscosity ratio after storage / before storage. When the viscosity does not change and is close to 1.0, the storage stability is good, and when it exceeds 1.5, clogging may occur at the time of injection, which is not preferable.

(Permeability evaluation for commercial recycled paper)
For images printed on commercially available recycled paper, permeability was evaluated according to the following criteria.
○: Almost no penetration and no residual monomer odor △: Slight penetration and slight residual monomer odor X: Clearly the ink penetrates the back side and the residual monomer odor is strong

(Evaluation of ink bleeding on grained aluminum support)
For images printed on a grained aluminum support, ink bleeding was evaluated according to the following criteria.
○: No blur between adjacent dots Δ: Slightly blur dots ×: Dot blurs and the image is clearly blurred

(Evaluation of adhesion in grained aluminum support)
For the printed image produced above, in accordance with JIS K 5400, a sample with no scratches on the printed surface and 11 cuts on the printed surface at 1 mm intervals in the vertical and horizontal directions. 100 samples were prepared, and a cellophane tape was affixed on each printing surface, quickly peeled off at an angle of 90 degrees, and the state of printed images or grids remaining without peeling was evaluated according to the following criteria.
○: No peeling of the printed image was observed even in the cross cut test. Δ: Some ink peeling was observed in the cross cut test, but almost no peeling was observed unless the ink surface was scratched. Easy to peel off with cellophane tape

(Evaluation of ejection stability)
After continuous discharge for 30 minutes, the presence or absence of defects due to nozzle clogging (presence / absence of unprinted portions) and fine dots (satellite) not set around the print dots on the printed matter were evaluated.
○: No nozzle defect or satellite is generated.
Δ: Nozzle defects or satellites are slightly generated.
X: Nozzle defects or satellites are remarkably generated.

(Evaluation of printed image quality)
The printed matter after curing was evaluated for matte feeling (concaveness), glossiness, and saturation.
○: Less matte feeling, good glossiness and saturation.
Δ: Matte feeling, glossiness and saturation slightly decreased.
X: Matte feeling is large and glossiness and saturation are greatly reduced. Banding (streak-like defect) occurs in part.

[Evaluation as a planographic printing plate]
An image was formed by printing with the ink composition of the present invention on the grained aluminum support prepared above. This was evaluated as a lithographic printing plate.
(Evaluation of printing durability)
An image was formed by printing with the ink composition of the present invention on the grained aluminum support prepared above. This is used as a lithographic printing plate on a Heidel KOR-D machine, and ink [VALUES-G Beni for sheet-fed (Dainippon Ink Co., Ltd.)] and dampening water [Ecolity 2 (Fuji Photo Film Co., Ltd.)] And printing was performed. Printing was continued as it was, and the relative number of finished sheets was compared as an index of printing durability (Comparative Example 1 was taken as 100). A larger numerical value is preferable because it has a higher printing durability.
These evaluation results are shown in Table 1.

[Example 9]
A magenta image was produced using the magenta ink 1 in the same manner as described in Example 1 except that an ultraviolet light emitting diode (UV-LED) was used instead of the metal halide lamp Vzero085 manufactured by Integration Technology.
In this example, NCCU033 manufactured by Nichia Chemical was used as the UV-LED. The LED outputs ultraviolet light having a wavelength of 365 nm from one chip. When a current of about 500 mA is applied, light of about 100 mW is emitted from the chip. A plurality of these are arranged at intervals of 7 mm, and a power of 0.3 W / cm ² can be obtained on the surface of a recording medium (hereinafter also referred to as a medium). The exposure time after the droplet ejection and the exposure time can be changed according to the transport speed of the medium and the distance between the head and the LED in the transport direction. In this embodiment, the exposure is performed about 0.5 seconds after landing.
Depending on the setting of the distance to the medium and the conveyance speed, the exposure energy on the medium can be adjusted between 0.01 and 15 J / cm ² .
As a result, inks so that tackiness disappeared when touched by such as the energy level that could completely cure the was 250 mJ / cm ^2. As recording media, each color image was recorded on a grained aluminum support, a transparent biaxially stretched polypropylene film having a printability, a soft vinyl chloride sheet, cast coated paper, and commercially available recycled paper. However, in both cases, a high-resolution image without dot bleeding was obtained. Furthermore, even on high-quality paper, the ink was sufficiently cured without causing the ink to turn around, and there was almost no odor due to unreacted monomers. Further, the ink recorded on the film had sufficient flexibility, and the ink was not cracked even when it was bent, and there was no problem in the adhesion test by peeling the cello tape (registered trademark).
Using a piezo ink jet head CA3 (manufactured by TOSHIBA TEC Corp.) and continuously projecting for 30 minutes, the state of the nozzles was confirmed. As a result, there was no problem with clogged nozzles. In addition, after immersing a piezo-type inkjet head CA3 (manufactured by Toshiba Tec Corporation) in the ink and allowing it to age for one week at 50 ° C., the corrosion (discoloration) of the immersed metal part was examined. There was no problem at all.

From the above results, the ink composition of each example is cured with high sensitivity to radiation irradiation, can form a high-quality image in terms of image formation on paper, and has good storage stability. there were. Thus, in the present invention, it can be seen that both curing sensitivity, suppression of bleeding on a non-permeable support and storage stability of ink have been achieved.
On the other hand, the ink compositions of Comparative Examples 1 and 2, which do not contain two or more amine compounds having different solubility parameters, have a problem in storage stability, and have good permeability to recycled paper, bleeding on an aluminum support, It was found that the curing sensitivity, ink ejection stability, and printed image quality were all inferior.
Further, it was found that the lithographic printing plate on which an image was formed with the ink composition of the present invention can form a high quality image and has good printing durability.

Claims (7)

(A) a cationically polymerizable compound,
(B) a compound that generates an acid upon irradiation with radiation,
(C) a colorant, and
(D) a radiation curable ink composition containing two or more amine compounds,
An ink composition, wherein the amine compound is two or more amine compounds having different solubility parameters.   The ink composition according to claim 1, which is for inkjet recording. (A) a step of discharging the ink composition onto a recording medium; and (b) a step of irradiating the discharged ink composition with active radiation to cure the ink composition;
An inkjet recording method comprising:
An ink jet recording method, wherein the ink composition is the ink composition according to claim 1. The active radiation is ultraviolet light emitted by a light emitting diode that generates ultraviolet light having an emission peak wavelength in the range of 350 to 420 nm and a maximum illuminance on the surface of the recording medium of 10 to 2,000 mW / cm ^2. The ink jet recording method according to claim 3.   A printed matter recorded by the ink jet recording method according to claim 3. (A) a step of ejecting the ink composition according to claim 1 or 2 onto a hydrophilic support; and (b) irradiating the ejected ink composition with actinic radiation to thereby remove the ink composition. Forming a hydrophobic image formed by curing the ink composition on the hydrophilic support by curing,
A method for producing a lithographic printing plate comprising   A lithographic printing plate produced by the method for producing a lithographic printing plate according to claim 6.