JP4709619B2 - Ink composition - Google Patents

Description

  The present invention relates to an ink composition capable of forming a high-quality image with good storage stability without lowering sensitivity, particularly a radiation-curable ink composition for ink jet recording, and an ink jet recording method using the same. And printed matter. The present invention also relates to a lithographic printing plate that requires no development processing, has high printing durability, and can form a high-quality image, and a method for producing the same.

  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.

In the inkjet image recording method, the curable ink jet method by radiation such as ultraviolet rays has been attracting attention in recent years because it has a relatively low odor and can be recorded on a recording medium without quick drying and ink absorption. is there. Such a radiation curable ink composition is required to provide sufficiently high sensitivity and high image quality, and also requires high storage stability. Ink compositions for ink jet recording are likely to be exposed to high temperature conditions during transportation and storage before they are put on the market after production. In such a case, even when light is blocked, polymerization and decomposition by heat proceeds, the ink itself gels, and the ink may not be stably ejected during printing.
On the other hand, examples of the ink composition curable by radiation as described above include an ink composition containing a polymerizable compound and a photopolymerization initiator. When such an ink composition is cured, the cured ink composition is used. There was a problem that a coloring phenomenon such as yellowing itself was observed. Such a coloring phenomenon is a problem particularly when an ink composition is used for image formation such as printing. Although the reason for the coloring phenomenon is not clear, it is presumed that the photopolymerization initiator is caused by a decomposition product decomposed during curing.
Patent Document 1 discloses an actinic ray curable inkjet ink composition containing at least one inclusion compound having a basic atomic group, but the ink storage stability is not sufficient.

JP 2004-99796 A

  The present invention relates to an ink composition capable of forming a high-quality image with good storage stability without lowering sensitivity, particularly a radiation-curable ink composition for ink jet recording, and an ink jet recording method using the same. And to provide printed matter. Another object of the present invention is to provide a lithographic printing plate that does not require development processing, has high printing durability, and can form a high-quality image, and a method for producing the same. Another object of the present invention is to provide an ink composition in which no coloring phenomenon such as yellowing is observed.

The above-mentioned subject contains (a) a polymerizable compound, (b) a photopolymerization initiator, and (c) an inclusion compound having at least one structure represented by the general formula (I) in the molecule. Achieved by the characterized ink composition.
The ink composition preferably further includes (d) a color material. In addition, it is preferable that the color material (d) is a pigment or an oil-soluble dye.
In a preferred embodiment of the present invention, the ink composition is an ink composition for ink jet recording.
Furthermore, the present invention provides an ink jet recording method comprising the steps of jetting and landing the ink composition on a recording medium, and the step of irradiating the ink composition with radiation to cure the ink composition. .
The present invention also provides a printed material obtained by jetting and landing the ink composition on a recording medium and then irradiating the ink composition to cure the ink composition.
The present invention also provides a lithographic printing plate characterized in that a hydrophobic region is formed by spraying the ink composition onto a hydrophilic support, landing, and then curing the ink by irradiation with radiation. A manufacturing method is provided.
The present invention further includes a lithographic printing plate having a hydrophobic region formed by jetting and landing the ink composition on a hydrophilic support and then curing the ink composition by irradiation with radiation. I will provide a.

The ink composition of the present invention includes an inclusion compound having at least one structure represented by the general formula (I) in the molecule. By using such an inclusion compound, sensitivity is improved. The storage stability is improved without lowering. The reason why the storage stability is improved is considered to be that the photopolymerization initiator or the polymerizable monomer is included in the inclusion compound, so that both are isolated during storage and the polymerization reaction does not proceed. On the other hand, the reason why the storage stability is improved without lowering the sensitivity is unknown, but the conformation of the clathrate compound is changed by the heat generated by light irradiation, and the encapsulated compound is easily released. I think because.
Further, when a cationically polymerizable compound is used and X in the general formula (I) is a nitrogen atom (NH or NR), the storage stability is further improved. This is presumably because the nitrogen atoms capture a small amount of acid generated from the initiator during storage. In addition, since at least one carbon atom adjacent to X is secondary or higher, it becomes a hindered amine, the nucleophilicity of the nitrogen atom is reduced, side reactions are suppressed, the polymerization reaction proceeds rapidly, and high sensitivity is achieved. It seems to have been achieved.
In addition, by using the inclusion compound of the present invention in which at least one carbon atom adjacent to at least one atom selected from nitrogen, oxygen or sulfur atoms is secondary or higher, coloring (yellowing) at the time of ink curing can be achieved. There is an effect that it is remarkably suppressed. Although the cause of this is not clear, the inclusion compound of the present invention and the initiator decomposition product (substance presumed to cause yellowing) interacted or caused a chemical reaction to change the structure of the decomposition product. Conceivable.
As described above, it is possible to provide an ink composition which is important as ink performance and has high sensitivity and storage stability and can form a high-quality image.

(1) Ink composition (1-1) Inclusion compound In this specification, an inclusion compound refers to various ions, atoms or molecules identified in cavities in a molecule or in a molecular assembly. It is defined as a compound that is taken into the cavity by the interaction of
The ink composition of the present invention is an inclusion compound having at least one atom selected from nitrogen, oxygen or sulfur atoms, and the carbon atom adjacent to the atom is a secondary or tertiary carbon atom An inclusion compound. That is, a carbon atom adjacent to at least one atom selected from nitrogen, oxygen, or sulfur atom is a secondary or tertiary branched carbon atom.
By using the above clathrate compound, the storage stability was dramatically improved while maintaining the high sensitivity of the ink composition. The reason why the storage stability is improved is considered to be that the photopolymerization initiator or the polymerizable monomer is encapsulated in the inclusion compound, and the two are isolated. In addition, it is considered that the inclusion compound has a basic atom such as nitrogen or oxygen, whereby the acid generated from the photopolymerization initiator is captured during storage and contributes to stability. Moreover, yellowing at the time of hardening of an ink composition is suppressed by using the said clathrate compound.

（式中、Ｘは、ＮＨまたはＮＲ、酸素、もしくは硫黄原子を表す。Ｒ¹、Ｒ²はそれぞれ独立して水素原子もしくは置換若しくは非置換の炭化水素基を表し、Ｒ¹、Ｒ²のうち少なくとも一つは置換若しくは非置換の炭化水素基である。Ｒは置換若しくは非置換のアルキル基である。） The clathrate compound used in the ink composition of the present invention has at least one partial structure represented by the general formula (I) in the molecule.

(In the formula, X represents NH or NR, oxygen, or a sulfur atom. R ¹ and R ² each independently represents a hydrogen atom or a substituted or unsubstituted hydrocarbon group, and R ¹ and R ² are (At least one is a substituted or unsubstituted hydrocarbon group, and R is a substituted or unsubstituted alkyl group.)

In the definition of R ¹ and R ² , examples of the hydrocarbon group include groups selected from the group consisting of linear, branched, or cyclic C1-C10 alkyl groups and aryl groups. More preferred is a linear, branched or cyclic C1-C10 alkyl group, and more preferred is a linear, branched or cyclic C1-C3 alkyl group. In the definition of R ¹ and R ² , examples of the substituent include a hydroxyl group, a halogen, a carboxyl group, an amino group, and a carbamoyl group.
In the above definition R, examples of the alkyl group include a C1-C10 linear, branched, or cyclic alkyl group, more preferably a C1-C3 alkyl group. Examples of the substituent include a hydroxyl group, a halogen, a carboxyl group, an amino group, and a carbamoyl group.

  The inclusion compound is preferably used in the range of 0.01 to 5% by mass with respect to the total weight of the ink composition of the present invention.

  The clathrate compound used in the present invention (the host compound of the clathrate compound is referred to here for convenience) as long as it has at least one structure represented by the general formula (I) in the molecule. There is no particular limitation. Examples of the inclusion compound include cyclic D-glucans, cyclophanes, neutral polyligands, cyclic polyanions, cyclic polycations, cyclic peptides, SPHERANDS, CAVITANDS, and acyclic analogs thereof. Can be mentioned. Among these, cyclic D-glucans and acyclic analogs thereof and cyclophanes are more preferable.

Examples of cyclic D-glucans and non-cyclic analogs thereof include compounds in which α-D-glucopyranose is linked by a glycoxide bond. In the present invention, the following compounds are preferably used.

はシクロデキストリンを表す。 In the above structural formula,

Represents cyclodextrin.

  Examples of cyclodextrin production are described in “Jonal of the American Chemical Society”, Volume 71, page 354, 1949, “Cheimish Berichte”, volume 90, page 2561, 1949, volume 90, page 2561, 1957. Of course, the present invention is not limited to these.

  The cyclodextrin of the present invention includes branched cyclodextrins and cyclodextrin polymers. Branched cyclodextrin is a known cyclodextrin obtained by adding or binding a water-soluble substance such as monosaccharide or disaccharide such as glucose, maltose, cellobiose, lactose, sucrose, galactose, glucosamine or the like, preferably , Maltosylcyclodextrin with maltose bound to cyclodextrin (maltose may have one, two, three, etc.), or glucosylcyclodextrin with glucose bound to cyclodextrin (glucose binding molecule The number may be 1 molecule, 2 molecules, 3 molecules, etc.).

  Specific methods for synthesizing these branched cyclodextrins include, for example, Starch Chemistry, Vol. 33, No. 2, 119-126 (1986), 127-132 (1986), Starch Chemistry, Vol. 30, Vol. No. 2, pages 231 to 239 (1983), etc., and can be synthesized with reference to these known methods. For example, maltosyl cyclodextrin uses cyclodextrin and maltose as raw materials, and is an isoamylase or pullulanase. It can be produced by a method of binding maltose to cyclodextrin using an enzyme such as Glucosylcyclodextrin can be produced by the same method.

  The branched cyclodextrins preferably used in the present invention include α-cyclodextrin with one molecule of maltose, β-cyclodextrin with one molecule of maltose, γ-cyclodextrin with one molecule of maltose, and two molecules of maltose. Α-cyclodextrin bound, β-cyclodextrin bound to two molecules of maltose, γ-cyclodextrin bound to two molecules of maltose, α-cyclodextrin bound to three molecules of maltose, β-cyclodextrin bound to three molecules of maltose Γ-cyclodextrin with 3 molecules of maltose, α-cyclodextrin with 1 molecule of glucose, β-cyclodextrin with 1 molecule of glucose, γ-cyclodextrin with 1 molecule of glucose, gluco- Α-cyclodextrin in which 2 molecules are bonded, β-cyclodextrin in which 2 molecules of glucose are bonded, γ-cyclodextrin in which 2 molecules of glucose are bonded, α-cyclodextrin in which 3 molecules of glucose are bonded, β in which 3 molecules of glucose are bonded -Cyclodextrin, γ-cyclodextrin in which 3 molecules of glucose are bonded, and the like.

  Further, cyclophanes can be used as the inclusion compound (host compound). Cyclophanes are cyclic compounds having a structure in which aromatic rings are connected by various bonds, and many compounds are known. Examples of cyclophanes include these known compounds. Among the inclusion compounds, these cyclophane compounds are preferable from the viewpoint of both storage stability and yellowing suppression, and particularly preferable when X is a nitrogen atom.

The bond connecting the aromatic rings is a partial structure represented by the general formula (I). Examples of such a compound include cyclophanes represented by the following formula.

  These cyclophanes preferably have a molecular weight in the range of 150 to 1500, and more preferably in the range of 400 to 1000.

(1-2) Polymerizable Compound As the polymerizable compound contained in the ink composition of the present invention, a polymerizable compound such as a radical polymerizable compound or a cationic polymerizable compound can be used.
As the radical polymerizable compound, various known radical polymerizable monomers can be used as a curing agent or a polymerizable diluent. The polymerizable functional group of the radically polymerizable monomer can be arbitrarily selected for the purpose of adjusting the polymerizability and the physical properties of the ink and the cured composition, but as a radically polymerizable monomer (meth) from the viewpoint of polymerization speed and versatility. Monomers derived from acrylates are preferably used. Moreover, a hardening | curing agent or polymeric diluent can be mixed and used for arbitrary ratios according to the physical property of an ink or a hardening composition.

Examples of monomers derived from (meth) acrylates used in the present invention (hereinafter also referred to as (meth) acrylates) include the following.
Monofunctional (meth) acrylates include hexyl (meth) acrylate (hexyl (meth) acrylate, the same applies hereinafter), 2-ethylhexyl (meth) acrylate, tert-octyl (meth) acrylate, isoamyl (meth) acrylate, decyl (Meth) acrylate, isodecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, 4-n-butylcyclohexyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) ) Acrylate, benzyl (meth) acrylate, 2-ethylhexyl diglycol (meth) acrylate, butoxyethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 4-bromobutyl (meth) ) Acrylate, cyanoethyl (meth) acrylate, benzyl (meth) acrylate, butoxymethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, alkoxymethyl (meth) acrylate, alkoxyethyl (meth) acrylate, 2- (2- Methoxyethoxy) ethyl (meth) acrylate, 2- (2-butoxyethoxy) ethyl (meth) acrylate, 2,2,2-tetrafluoroethyl (meth) acrylate, 1H, 1H, 2H, 2H-perfluorodecyl (meta ) Acrylate, 4-butylphenyl (meth) acrylate, phenyl (meth) acrylate, 2,4,5-tetramethylphenyl (meth) acrylate, 4-chlorophenyl (meth) acrylate, phenoxymethyl (meth) acrylate, phenoxy Ethyl (meth) acrylate, glycidyl (meth) acrylate, glycidyloxybutyl (meth) acrylate, glycidyloxyethyl (meth) acrylate, glycidyloxypropyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, hydroxyalkyl ( (Meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3 -Hydroxypropyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethyl acrylate Minopropyl (meth) acrylate, trimethoxysilylpropyl (meth) acrylate, trimethylsilylpropyl (meth) acrylate, polyethylene oxide monomethyl ether (meth) acrylate, oligoethylene oxide monomethyl ether (meth) acrylate, polyethylene oxide (meth) acrylate, oligoethylene oxide ( (Meth) acrylate, oligoethylene oxide monoalkyl ether (meth) acrylate, polyethylene oxide monoalkyl ether (meth) acrylate, dipropylene glycol (meth) acrylate, polypropylene oxide monoalkyl ether (meth) acrylate, oligopropylene oxide monoalkyl ether (meta) ) Acrylate, 2-methacryloyloxytylcho Acid, 2-methacryloyloxyhexahydrophthalic acid, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, butoxydiethylene glycol (meth) acrylate, trifluoroethyl (meth) acrylate, perfluorooctylethyl (meth) acrylate, 2 -Hydroxy-3-phenoxypropyl (meth) acrylate, EO modified phenol (meth) acrylate, EO modified cresol (meth) acrylate, EO modified nonylphenol (meth) acrylate, PO modified nonylphenol (meth) acrylate, EO modified-2-ethylhexyl (Meth) acrylate is mentioned.

  Specific examples of the bifunctional (meth) acrylates include 1,6-hexanediol di (meth) acrylate, 1,10-decanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 2,4- Dimethyl-1,5-pentanediol di (meth) acrylate, butylethylpropanediol (meth) acrylate, ethoxylated cyclohexanemethanol di (meth) acrylate, polyethylene glycol di (meth) acrylate, oligoethylene glycol di (meth) acrylate , Ethylene glycol di (meth) acrylate, 2-ethyl-2-butyl-butanediol di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, EO-modified bisphenol A di (meth) acrylate Bisphenol F polyethoxydi (meth) acrylate, polypropylene glycol di (meth) acrylate, oligopropylene glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 2-ethyl-2-butylpropanediol di (Meth) acrylate, 1,9-nonane di (meth) acrylate, propoxylated ethoxylated bisphenol A di (meth) acrylate, tricyclodecane di (meth) acrylate and the like.

  Specific examples of trifunctional (meth) acrylates include trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, trimethylolpropane alkylene oxide modified tri (meth) acrylate, pentaerythritol tri (meth) Acrylate, dipentaerythritol tri (meth) acrylate, trimethylolpropane tri ((meth) acryloyloxypropyl) ether, isocyanuric acid alkylene oxide modified tri (meth) acrylate, dipentaerythritol tri (meth) acrylate propionate, tri (( (Meth) acryloyloxyethyl) isocyanurate, hydroxypivalaldehyde-modified dimethylolpropane tri (meth) acrylate, sorbitol tri (meth) a Relate, propoxylated trimethylolpropane tri (meth) acrylate, and ethoxylated glycerin triacrylate.

  Specific examples of tetrafunctional (meth) acrylates include pentaerythritol tetra (meth) acrylate, sorbitol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate propionate, ethoxylation Examples include pentaerythritol tetra (meth) acrylate.

  Specific examples of pentafunctional (meth) acrylates include sorbitol penta (meth) acrylate and dipentaerythritol penta (meth) acrylate.

  Specific examples of hexafunctional (meth) acrylates include dipentaerythritol hexa (meth) acrylate, sorbitol hexa (meth) acrylate, phosphazene alkylene oxide modified hexa (meth) acrylate, captolactone modified dipentaerythritol hexa (meth) An acrylate etc. can be mentioned.

  In the present specification, “(meth) acrylate” is an abbreviated notation indicating that a structure of both methacrylate and acrylate can be taken.

Examples of monomers other than (meth) acrylates include the following.
Examples of (meth) acrylamides include (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, Nn-butyl (meth) acrylamide, N -T-butyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-methylol (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl ( Examples include meth) acrylamide and meth) acryloylmorpholine. Here, (meth) acrylamide indicates that it can have both methacrylamide and acrylamide structures.

Specific examples of olefins include dicyclopentadiene, ethylene, propylene, 1-butene, 1-pentene, vinyl chloride, vinylidene chloride, isoprene, chloroprene, butadiene, 2,3-dimethylbutadiene, and cyclohexadiene. It is done.
Specific examples of styrenes include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropyl styrene, chloromethyl styrene, methoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, bromo styrene, methyl vinyl benzoate. Ester, 3-methylstyrene, 4-methylstyrene, 3-ethylstyrene, 4-ethylstyrene, 3-propylstyrene, 4-propylstyrene, 3-butylstyrene, 4-butylstyrene, 3-hexylstyrene, 4-hexyl Styrene, 3-octyl styrene, 4-octyl styrene, 3- (2-ethylhexyl) styrene, 4- (2-ethylhexyl) styrene, allyl styrene, isopropenyl styrene, butenyl styrene, octenyls Ren, 4-t-butoxycarbonyl styrene, 4-methoxystyrene, and a 4-t-butoxystyrene.

  Examples of vinyl ethers include methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, methoxy vinyl ether, 2-ethylhexyl vinyl ether, methoxyethyl vinyl ether, cyclohexyl vinyl ether, and chloroethyl vinyl ether.

  Other monomers include butyl crotonate, hexyl crotonate, dimethyl itaconate, dibutyl itaconate, diethyl maleate, dimethyl maleate, dibutyl maleate, diethyl fumarate, dimethyl fumarate, methyl vinyl ketone, phenyl vinyl ketone, methoxyethyl Vinyl ketone, N-vinyl oxazolidone, N-vinyl pyrrolidone, vinyl formamide, vinylidene chloride, methylenemalononitrile, vinylidene, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, dibutyl-2- Acryloyloxyethyl phosphate, dioctyl-2-methacryloyloxyethyl phosphate, vinyl acetate, vinyl benzoate, N-vinylcarbazo Etc. The.

  Moreover, a cationically polymerizable compound can be used for the polymerizable compound of the present invention. As the cationic polymerizable compound, for example, a cationic polymerization-based photocurable resin is known, and recently, a photocationic polymerization-based photocurable resin sensitized to a long wavelength region longer than visible light is also available, for example. They are disclosed in Kaihei 6-43333, JP-A-8-324137, and the like.

  Various known cationic polymerizable compounds (monomers) can be used as the cationic polymerizable compound. Examples thereof include JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-310937, and JP-A-2001-220526. An epoxy compound, a vinyl ether compound, an oxetane compound, etc. are mentioned. Examples of the cationically polymerizable compound of the present invention include oxetane compounds, epoxy compounds, vinyl ether compounds, or combinations thereof.

  The (a) oxetane compound is a compound having an oxetane ring, and examples thereof include all known oxetane compounds as introduced in JP-A Nos. 2001-220526 and 2001-310937. In particular, a compound containing an oxetane ring represented by the following general formula (1) is preferable.

一般式（１）において、Ｒ₁〜Ｒ₆は、各々水素原子または置換基を表す。ただし、Ｒ₃〜Ｒ₆で表される基の少なくとも一つは置換基である。

In General formula (1), R < ₁ > -R < ₆ > represents a hydrogen atom or a substituent respectively. However, at least one of the groups represented by R _{3 to} R ₆ is a substituent.

In the general formula (1), examples of the substituent represented by R _{1 to} R ₆ include a fluorine atom and an alkyl group having 1 to 6 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, a butyl group). Etc.), a C1-C6 fluoroalkyl group, an allyl group, an aryl group (for example, a phenyl group, a naphthyl group, etc.), a furyl group, or a thienyl group. Moreover, these groups may further have a substituent.

Examples of the compound having one oxetane ring in the molecule include compounds represented by the following general formulas (2) to (5).

In the above general formulas (2) to (5), R _{1 to} R ₆ each represent a group having the same meaning as in the general formula (1), Z is independent, oxygen or sulfur atom, or oxygen or sulfur atom in the main chain Represents a divalent hydrocarbon group which may contain
In the general formulas (2) to (5), the substituents represented by R ₇ and R ₈ are each an alkyl group having 1 to 6 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, or a butyl group). Etc.), an alkenyl group having 1 to 6 carbon atoms (for example, 1-propenyl group, 2-propenyl group, 2-methyl-1-propenyl group, 2-methyl-2-propenyl group, 1-butenyl group, 2- Butenyl group, 3-butenyl group, etc.), aryl group (eg, phenyl group, naphthyl group, etc.), aralkyl group (eg, benzyl group, fluorobenzyl group, methoxybenzyl group, etc.), acyl group having 1 to 6 carbon atoms (For example, propylcarbonyl group, butylcarbonyl group, pentylcarbonyl group, etc.), C1-C6 alkoxycarbonyl group (for example, ethoxycarbonyl group, propoxycarbonyl group) Butoxycarbonyl group), it represents the number 1-6 alkylcarbamoyl group having a carbon (e.g., propylcarbamoyl group, butyl pentylcarbamoyl group), alkoxy carbamoyl group (e.g., ethoxy carbamoyl group).

  In the general formulas (2) to (5), an oxygen or sulfur atom represented by Z or a divalent hydrocarbon group which may contain an oxygen or sulfur atom in the main chain is an alkylene group (for example, Ethylene group, trimethylene group, tetramethylene group, propylene group, ethylethylene group, pentamethylene group, hexamethylene group, heptamethylene group, octamethylene group, nonamethylene group, decamethylene group, etc.), alkenylene group (for example, vinylene group, propenylene) Group), alkynylene group (for example, ethynylene group, 3-pentynylene group, etc.), and the carbon atom of the aforementioned alkylene group, alkenylene group, alkynylene group may be replaced by an oxygen atom or a sulfur atom. .

As the oxetane ring-containing compound that can be used in the present invention, in the above general formulas (2) to (5), R ₁ is a lower alkyl group, particularly an ethyl group, and R ₇ and R ₈ are a propyl group, a butyl group, and a phenyl group. Or a benzyl group, wherein Z is a hydrocarbon group containing no oxygen or sulfur atom (an alkylene group, an alkenylene group, an alkynylene group, etc.). At this time, at least one group represented by R _{3 to} R ₆ is a substituent.
Examples of the compound having two or more oxetane rings in the molecule include compounds represented by the following general formulas (6) and (7).

In the general formulas (6) and (7), m represents 2, 3 or 4, and Z has the same meaning as Z represented by the general formulas (2) to (5).
R _{1 to} R ₆ each represent a group having the same meaning as in the general formula (1). However, in General formula (6), at least 1 of R < ₃ > -R < ₆ > is a substituent.
R ₉ is selected from the group consisting of linear or branched alkylene groups having 1 to 12 carbon atoms, linear or branched poly (alkyleneoxy) groups, or the following general formulas (9), (10) and (11). Represents a divalent group. As said C1-C12 linear or branched alkylene group, group represented by following General formula (8) is preferable.

In the general formula (8), R ₁₀ represents a lower alkyl group such as a methyl group, an ethyl group, or a propyl group.

In the general formula (9), n is 0 or an integer of 1 to 2000, R ₁₁ is an alkyl group having 1 to 10 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group). , A heptyl group, an octyl group, a nonyl group, or the like) or a group selected from the following general formula (12). R ₁₂ represents an alkyl group having 1 to 10 carbon atoms (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, nonyl group, etc.).

In the general formula (12), j is 0 or an integer of 1 to 100, R ₁₃ is an alkyl group having 1 to 10 carbon atoms (for example, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, Hexyl group, heptyl group, octyl group, nonyl group, etc.).

In the general formula (10), R ₁₄ represents a hydrogen atom, an alkyl group having 1 to 10 carbon atoms (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, heptyl group, octyl group, Nonyl group, etc.), an alkoxy group having 1 to 10 carbon atoms (eg, methoxy group, ethoxy group, propoxy group, butoxy group, pentoxy group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom, iodine atom) Etc.), a nitro group, a cyano group, a mercapto group, an alkoxycarbonyl group (for example, a methyloxycarbonyl group, an ethyloxycarbonyl group, a butyloxycarbonyl group, etc.) or a carboxyl group.

In the general formula (11), R ₁₅ represents an oxygen atom, a sulfur atom, NH, SO, SO ₂ , CH ₂ , C (CH ₃ ) ₂ or C (CF ₃ ) ₂ .

Preferred embodiments of the partial structure of the oxetane ring-containing compound used in the present invention include, for example, in the above general formulas (6) and (7), R ₁ is a lower alkyl group (for example, a methyl group, an ethyl group, a propyl group). Etc.), particularly preferably an ethyl group. As R ₉ , a hexamethylene group or one in which R ₁₄ is a hydrogen atom in the general formula (10) is preferably used.

In the general formula (8), R ₁₀ is preferably an ethyl group, and in general formulas (9) and (12), R ₁₂ and R ₁₃ are each preferably a methyl group. However, at least one of the groups represented by R _{3 to} R ₆ in the general formula (6) is a substituent.

  Furthermore, examples of the compound having two or more oxetane rings in the molecule include compounds represented by the following general formula (13).

In the general formula (13), r is an integer of 25 to 200, R ₁₆ is an alkyl group or a trialkylsilyl group having 1 to 4 carbon atoms. R ₁ and R _{4 to} R ₆ have the same meanings as those in the general formula (1), and at least one of the groups represented by R _{3 to} R ₆ is a substituent.
Although the specific example of the compound containing the oxetane ring represented by General formula (1) based on this invention is shown in Table 1, this invention is not limited to these.

In addition, each of the above compounds can be easily synthesized mainly by the following scheme by referring to the following literature, including the method described in item 4 of “Catchball of Polymer Science and Organic Chemistry” The synthesis method is not limited to this.

1) Hu Xianming, Richard M. et al. Kellogg, Synthesis, 533-538, May (1995)
2) A. O. Fitton, J .; Hill, D.C. Ejane, R.A. Miller, Synth. , 12, 1140 (1987)
3) Toshiro Imai and Shinya Nishida, Can. J. et al. Chem. Vol. 59, 2503-2509 (1981)
4) Nobujiro Shimizu, Shintaro Yamaoka, and Yuho Tsuno, Bull. Chem. Soc. Jpn. 56, 3853-3854 (1983)
5) Walter Fisher and Cyril A. Grob, Helv. Chim. Acta. , 61, 2336 (1978)
6) Chem. Ber. 101, 1850 (1968)
7) “Heterocyclic Compounds with Three- and Four-membered Rings”, Part Two, Chapter IX, Interscience Publishers, John Wiley & Sons, N
8) H.M. A. J. et al. Curless, “Synthetic Organic Photochemistry”, Plenum, New York (1984).
9) M.M. Braun, Nachr. Chem. Tech. Lab. 33, 213 (1985)
10) S.M. H. Schroeter, J.A. Org. Chem. , 34, 5, 1181 (1969)
11) D. R. Arnold, Adv. Photochem. 6,301 (1968)

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

  As the alicyclic epoxide, cyclohexene oxide obtained by epoxidizing a compound having at least one cycloalkane ring such as cyclohexene or cyclopentene ring with a suitable oxidizing agent such as hydrogen peroxide or peracid. Or a cyclopentene oxide containing compound is preferable.

  Preferred aliphatic epoxides include di- or polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof, and typical examples thereof include diglycidyl ether of ethylene glycol, diglycidyl ether of propylene glycol or Diglycidyl ether of alkylene glycol such as diglycidyl ether of 1,6-hexanediol, polyglycidyl ether of polyhydric alcohol such as di- or triglycidyl ether of glycerin or its alkylene oxide adduct, polyethylene glycol or its alkylene oxide adduct Diglycidyl ethers of polyalkylene glycols such as diglycidyl ethers, polypropylene glycols or diglycidyl ethers of adducts thereof Tel and the like. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

  Among these epoxides, in view of fast curability, aromatic epoxides and alicyclic epoxides are preferable, and alicyclic epoxides are particularly preferable. In the present invention, one of the epoxides may be used alone, or two or more may be used in appropriate combination.

  In the present invention, from the viewpoint of mutagenicity test (AMES), sensitization test, etc., particularly from the viewpoint of safety to the human body, epoxy compounds having an oxirane group include epoxidized fatty acid esters, epoxidized fatty acid glycerides. Particularly preferred is at least one of the following.

The epoxidized fatty acid ester and epoxidized fatty acid glyceride are not particularly limited as long as an epoxy group is introduced into the fatty acid ester or fatty acid glyceride.
The epoxidized fatty acid ester is produced by epoxidizing an oleic acid ester, and examples thereof include methyl epoxy stearate, butyl epoxy stearate, octyl epoxy stearate and the like. Similarly, the epoxidized fatty acid glyceride is produced by epoxidizing soybean oil, linseed oil, castor oil and the like, and epoxidized soybean oil, epoxidized linseed oil, epoxidized castor oil and the like are used.

  (c) 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. , Di- or trivinyl ether compounds such as trimethylolpropane trivinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexane dimethanol monovinyl ether, n-propyl Pills vinyl ether, isopropyl vinyl ether, isopropenyl ether -O- propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, and octadecyl vinyl ether.

  Among these vinyl ether compounds, in consideration of curability, adhesion, and surface hardness, di- or trivinyl ether compounds are preferable, and divinyl ether compounds are particularly preferable. In the present invention, one of the above vinyl ether compounds may be used alone, or two or more thereof may be used in appropriate combination.

(Amount of polymerizable compound added)
The addition amount of the polymerizable compound of the present invention is, for example, 1 to 97% by mass, and more preferably 30 to 95% by mass with respect to the total mass of the ink composition of the present invention.

(1-3) Photopolymerization initiator Next, the photopolymerization initiator used in the ink composition of the present invention will be described.
The photopolymerization initiator in the present invention is a compound that undergoes a chemical change through the action of light or interaction with the electronically excited state of a sensitizing dye to generate at least one of radicals, acids, and bases. It is.
Examples of the polymerization initiator in the present invention include known radical polymerization or cationic polymerization photopolymerization initiators used in radiation-curable ink compositions. The other photopolymerization initiator that can be used in combination with the present invention causes a chemical change through the action of light or interaction with the electronically excited state of the sensitizing dye, and is at least one of a radical, an acid, and a base. A compound that produces one species. As the specific photopolymerization initiator, those known to those skilled in the art can be used without limitation. Specifically, for example, Bruce M. Monroe et al., Chemical Review, 93, 435 (1993), RSD Davidson, Journal of Photochemistry and biology A: Chemistry, 73, 81 (1993), JP Faussier "Photoinitiated Polymerization -Theory and Applications ": Rapra Review vol. 9, Report, Rapra Technology (1998) and M. Tsunooka et al., Prog. Polym. Sci., 21, 1 (1996). There are many chemical amplification type photoresists and compounds used for photocationic polymerization described in (Organic Electronics Materials Research Group, “Organic Materials for Imaging”, Bunshin Publishing (1993), pages 187-192). Has been. Furthermore, FDSaeva, Topics in Current Chemistry, 156, 59 (1990), GG Maslak, Topics in Current Chemistry, 168, 1 (1993), HB Shuster et al, J. Am. Chem. Soc., 112, 6329 ( 1990), IDFEaton et al, J. Am. Chem. Soc, 102, 3298 (1980) and the like, through the interaction with the electronically excited state of the sensitizing dye, oxidatively or reductively. A group of compounds that cause bond cleavage is also known.

  Preferred photopolymerization initiators include (a) aromatic ketones, (b) aromatic onium salt compounds, (c) organic peroxides, (d) hexaarylbiimidazole compounds, (e) ketoxime ester compounds, (F) a borate compound, (g) an azinium compound, (h) a metallocene compound, (i) an active ester compound, (j) a compound having a carbon halogen bond, and the like.

  (A) Preferable examples of aromatic ketones include compounds having a benzophenone skeleton or a thioxanthone skeleton described in “RADIATION CURING IN POLYMER SCIENCE AND TECHNOLOGY” J. P. FOUASSIER J. F. RABEK (1993), p77-117. More preferable examples of (a) aromatic ketones include α-thiobenzophenone compounds described in JP-B-47-6416, benzoin ether compounds described in JP-B-47-3981, and JP-B-47-22326. Α-substituted benzoin compounds, benzoin derivatives described in JP-B-47-23664, aroylphosphonic acid esters described in JP-A-57-30704, dialkoxybenzophenones described in JP-B-60-26483, Benzoin ethers described in JP-A-60-26403, JP-A-62-81345, JP-B-1-34242, US Pat. No. 4,318,791, and α-aminobenzophenones described in European Patent 0284561A1, P-di (dimethyla) described in JP-A-2-211452 Nobenzoyl) benzene, thio-substituted aromatic ketone described in JP-A-61-194062, acylphosphine sulfide described in JP-B-2-9597, acylphosphine described in JP-B-2-9596, JP-B-63- Examples thereof include thioxanthones described in Japanese Patent No. 61950, and coumarins described in Japanese Patent Publication No. 59-42864.

  (B) As aromatic onium salt compounds, elements of Groups 15, 16 and 17 of the periodic table, specifically N, P, As, Sb, Bi, O, S, Se, Te, or I fragrances Group onium salts are included. For example, iodonium salts described in European Patent No. 104143, US Pat. No. 4,837,124, Japanese Patent Laid-Open No. 2-150848, Japanese Patent Laid-Open No. 2-96514, European Patent Nos. 370693, 233567, and 297443 are disclosed. The diazonium salts described in the specifications of U.S. Pat. Nos. 2,974,279, 279210, and 422570, U.S. Pat. Nos. 3,902,144, 4,933,377, 4,760013, 4,734,444, and 2,833,827. Benzenediazonium which may have a substituent), diazonium salt resins (formaldehyde resin of diazodiphenylamine, etc.), N-alkoxypyridinium salts, etc. (for example, US Pat. No. 4,743,528, JP-A-63) -138345, JP-A-63 142345, JP-A-63-142346, and JP-B-46-42363, specifically 1-methoxy-4-phenylpyridinium tetrafluoroborate, etc. The compounds described in JP-A 52-147277, 52-14278, and 52-14279 are preferably used. Generates radicals and acids as active species.

  (C) The organic peroxide includes almost all organic compounds having one or more oxygen-oxygen bonds in the molecule. Examples thereof include 3,3′4,4′-tetra- (t -Butylperoxycarbonyl) benzophenone, 3,3'4,4'-tetra- (t-amylperoxycarbonyl) benzophenone, 3,3'4,4'-tetra- (t-hexylperoxycarbonyl) benzophenone, 3,3′4,4′-tetra- (t-octylperoxycarbonyl) benzophenone, 3,3′4,4′-tetra- (cumylperoxycarbonyl) benzophenone, 3,3′4,4′-tetra Peroxide esters such as-(p-isopropylcumylperoxycarbonyl) benzophenone and di-t-butyldiperoxyisophthalate are preferred.

  (D) Examples of hexaarylbiimidazole compounds include lophine dimers described in JP-B Nos. 45-37377 and 44-86516, such as 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-bromophenyl) -4,4 ′, 5,5′tetraphenylbiimidazole, 2,2′-bis (o, p-dichlorophenyl) -4,4 ', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o-chlorophenyl) -4,4', 5,5'-tetra (m-methoxyphenyl) biimidazole, 2, 2′-bis (o, o′-dichlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-nitrophenyl) -4,4 ′, 5,5 ′ − Traphenylbiimidazole, 2,2′-bis (o-methylphenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, 2,2′-bis (o-trifluorophenyl) -4,4 Examples include ', 5,5'-tetraphenylbiimidazole.

  (E) Examples of ketoxime ester compounds include 3-benzoyloxyiminobutan-2-one, 3-acetoxyiminobutan-2-one, 3-propionyloxyiminobutan-2-one, and 2-acetoxyiminopentane-3. -One, 2-acetoxyimino-1-phenylpropan-1-one, 2-benzoyloxyimino-1-phenylpropan-1-one, 3-p-toluenesulfonyloxyiminotan-2-one, 2-ethoxy And carbonyloxyimino-1-phenylpropan-1-one.

  (F) Examples of borate compounds include those described in the specifications of US Pat. Nos. 3,567,453, 4,343,891, European Patents 109,772, and 109,773. Can be mentioned.

  (G) Examples of azinium salt compounds include JP-A 63-138345, JP-A 63-142345, JP-A 63-142346, JP-A 63-143537, and JP-B 46-42363. The compound group which has NO bond of each gazette description can be mentioned.

  (H) Examples of metallocene compounds include titanocenes described in JP-A-59-152396, JP-A-61-151197, JP-A-63-41484, JP-A-2-249, and JP-A-2-4705. Examples thereof include iron-arene complexes described in JP-A-1-304453 and JP-A-1-152109.

  Specific examples of the titanocene compound include di-cyclopentadienyl-Ti-di-chloride, di-cyclopentadienyl-Ti-bis-phenyl, and di-cyclopentadienyl-Ti-bis-2,3. 4,5,6-pentafluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,3,5,6-tetrafluorophen-1-yl, di-cyclopentadienyl-Ti- Bis-2,4,6-trifluorophen-1-yl, di-cyclopentadienyl-Ti-2,6-difluorophen-1-yl, di-cyclopentadienyl-Ti-bis-2,4 -Difluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,3,4,5,6-pentafluorophen-1-yl, di-methylcyclopentadienyl-Ti- -2,3,5,6-tetrafluorophen-1-yl, di-methylcyclopentadienyl-Ti-bis-2,4-difluorophen-1-yl, bis (cyclopentadienyl) -bis (2,6-difluoro-3- (pyridin-1-yl) phenyl) titanium, bis (cyclopentadienyl) bis [2,6-difluoro-3- (methylsulfonamido) phenyl] titanium, bis (cyclopenta And dienyl) bis [2,6-difluoro-3- (N-butylbialoyl-amino) phenyl] titanium.

  (I) Examples of active ester compounds include the specifications of European Patent Nos. 0290750, 046083, 156153, 271851, and 0388343, U.S. Pat. Nos. 3,901,710, and 4,181,531. Nitrobenzol ester compounds described in JP-A-60-198538 and JP-A-53-133022, European Patents 0199672, 84515, 199672, 0441115, and 0101122. No. 4,618,564, U.S. Pat. No. 4,371,605, and U.S. Pat. No. 4,431,774, JP-A 64-18143, JP-A 2-245756, and JP-A-4-365048. Iminosulfonate compound, Japanese Examined Patent Publication No. 62-6223, Japanese Examined Publication No. 63 No. 14340, and compounds, and the like described in the JP-A No. 59-174831.

  (J) Preferable examples of the compound having a carbon halogen bond include, for example, compounds described in Wakabayashi et al., Bull. Chem. Soc. Japan, 42, 2924 (1969), compounds described in British Patent No. 1388492, Examples thereof include compounds described in Japanese Utility Model Publication No. 53-133428, compounds described in German Patent No. 3337024, and the like.

Further, compounds described in J. Org. Chem., 29, 1527 (1964) by FC Schaefer et al., Compounds described in JP-A-62-258241, compounds described in JP-A-5-281728, and the like can be mentioned. it can. A compound as described in German Patent No. 2641100, a compound described in German Patent No. 3333450, a compound group described in German Patent No. 3021590, or a compound group described in German Patent No. 3021599, etc. Can be mentioned.
Preferable specific examples of the compounds represented by the above (a) to (j) include those shown below.

  When the other polymerization initiators described above are used in combination, the content thereof is preferably 0.1 to 20% by weight with respect to the total solid content of the ink composition.

(1-4) Sensitizing dye In the present invention, a sensitizing dye may be added for the purpose of improving the sensitivity of the photopolymerization initiator. Examples of preferred sensitizing dyes include those belonging to the following compounds and having an absorption wavelength in the 350 nm to 450 nm region.
Polynuclear aromatics (eg, pyrene, perylene, triphenylene), xanthenes (eg, fluorescein, eosin, erythrosine, rhodamine B, rose bengal), cyanines (eg, thiacarbocyanine, oxacarbocyanine), merocyanines ( For example, merocyanine, carbomerocyanine), thiazines (eg, thionine, methylene blue, toluidine blue), acridines (eg, acridine orange, chloroflavin, acriflavine), anthraquinones (eg, anthraquinone), squalium (eg, squalium) ), Coumarins (eg, 7-diethylamino-4-methylcoumarin).

More preferable examples of the sensitizing dye include compounds represented by the following general formulas (IX) to (XIII).

(In Formula (IX), A ¹ represents a sulfur atom or NR ⁵⁰ , R ⁵⁰ represents an alkyl group or an aryl group, and L ² represents a basic nucleus of the dye in combination with the adjacent A ² and the adjacent carbon atom. Represents a nonmetallic atomic group to be formed, R ⁵¹ and R ⁵² each independently represent a hydrogen atom or a monovalent nonmetallic atomic group, and R ⁵¹ and R ⁵² are bonded to each other to form an acidic nucleus of the dye. W represents an oxygen atom or a sulfur atom.)

(In the formula (X), Ar ¹ and Ar ² each independently represent an aryl group and are linked via a bond with —L ³ —, where L ³ represents —O— or —S—. W has the same meaning as that shown in formula (IX).)

(In the formula (XI), A ² represents a sulfur atom or NR ⁵⁹ , L ⁴ represents a nonmetallic atomic group that forms a basic nucleus of the dye in combination with adjacent A ² and a carbon atom, R ⁵³ , R ⁵⁴ , R ⁵⁵ , R ⁵⁶ , R ⁵⁷ and R ⁵⁸ each independently represent a monovalent nonmetallic atomic group, and R ⁵⁹ represents an alkyl group or an aryl group.)

(In Formula (XII), A ³ and A ⁴ each independently represent —S— or —NR ⁶² — or —NR ⁶³ —, wherein R ⁶² and R ⁶³ each independently represent a substituted or unsubstituted alkyl group, substituted Or an unsubstituted aryl group, L ⁵ and L ⁶ each independently represent a nonmetallic atomic group that forms a basic nucleus of a dye in cooperation with adjacent A ³ , A ^4, and adjacent carbon atoms; ⁶⁰ and R ⁶¹ are each independently a hydrogen atom or a monovalent nonmetallic atomic group, or can be bonded to each other to form an aliphatic or aromatic ring.

(In the formula (XIII), R ⁶⁶ represents an aromatic ring or a hetero ring which may have a substituent, and A ⁵ represents an oxygen atom, a sulfur atom or —NR ⁶⁷ —. R ⁶⁴ , R ⁶⁵ and R ⁶⁷ each independently represents a hydrogen atom or a monovalent non-metallic atomic group, and R ⁶⁷ and R ⁶⁴ , and R ⁶⁵ and R ⁶⁷ may be bonded to each other to form an aliphatic or aromatic ring. it can.)

  Preferable specific examples of the compounds represented by the general formulas (IX) to (XIII) include those shown below.

(1-5) Co-sensitizer Further, the ink composition of the present invention may be added with a known compound as a co-sensitizer that has a function of further improving sensitivity or suppressing polymerization inhibition by oxygen. good.

  Examples of such co-sensitizers include amines such as MR Sander et al., “Journal of Polymer Society”, Vol. 10, page 3173 (1972), Japanese Examined Patent Publication No. 44-20189, Japanese Patent Laid-Open No. 51-82102. Publication, JP 52-134692, JP 59-138205, JP 60-84305, JP 62-18537, JP 64-33104, Research Disclosure 33825 Specifically, triethanolamine, p-dimethylaminobenzoic acid ethyl ester, p-formyldimethylaniline, p-methylthiodimethylaniline and the like can be mentioned.

  Other examples include thiols and sulfides, for example, thiol compounds described in JP-A-53-702, JP-B-55-500806, JP-A-5-142772, and JP-A-56-75643. Examples thereof include disulfide compounds, and specific examples include 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-mercaptobenzimidazole, 2-mercapto-4 (3H) -quinazoline, β-mercaptonaphthalene and the like.

  Other examples include amino acid compounds (eg, N-phenylglycine), organometallic compounds described in Japanese Patent Publication No. 48-42965 (eg, tributyltin acetate), and hydrogen described in Japanese Patent Publication No. 55-34414. Donors, sulfur compounds described in JP-A-6-308727 (eg, trithiane), phosphorus compounds described in JP-A-6-250387 (diethylphosphite, etc.), Si-- described in Japanese Patent Application No. 6-191605 H, Ge-H compound, etc. are mentioned.

(1-6) Coloring material It is preferable to add a coloring material to the ink composition of the invention. This is because a visible image can be formed by adding a coloring material to the ink composition of the present invention. For example, when forming an image area of a lithographic printing plate, it is not always necessary to add a coloring material to the ink composition, but from the viewpoint of plate inspection of the obtained lithographic printing plate, the coloring material It is also preferable to use.

The color material that can be used in the present invention is not particularly limited, but various known color materials (pigments and dyes) can be appropriately selected and used depending on the application. For example, when forming an image excellent in weather resistance, a pigment is preferable. As the dye, either a water-soluble dye or an oil-soluble dye can be used. However, since the cationic polymerization initiator is susceptible to hydrolysis by moisture (humidity) or the like, an oil-soluble dye that hardly absorbs moisture is preferable.
Although it does not necessarily limit as a coloring material of this invention, For example, the organic or inorganic pigment of the following number described in a color index can be used.

  That is, as red or magenta pigment, Pigment Red 3, 5, 19, 22, 31, 38, 43, 48: 1, 48: 2, 48: 3, 48: 4, 48: 5, 49: 1, 53 : 1, 57: 1, 57: 2, 58: 4, 63: 1, 81, 81: 1, 81: 2, 81: 3, 81: 4, 88, 104, 108, 112, 122, 123, 144 146, 149, 166, 168, 169, 170, 177, 178, 179, 184, 185, 208, 216, 226, 257, Pigment Violet 3, 19, 23, 29, 30, 37, 50, 88, Pigment Orange 13, 16, 20, 36, blue or cyan pigments include Pigment Blue 1, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16 17-1, 22, 27, 28, 29, 36, 60, as green pigment, Pigment Green 7, 26, 36, 50, as yellow pigment, Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, 137, 138, 139, 153, 154, 155, 157, 166, 167, 168, 180, 185, 193, Pigment Black 7, 28, 26 as the black pigment, and Pigment White 6, 18, 21, etc. as the white pigment can be used according to the purpose.

  In the present invention, the coloring material needs to be appropriately dispersed in the ink after being added to the ink composition of the present invention. For dispersion of the color material, for example, a dispersion device such as a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, or a paint shaker can be used.

  It is also possible to add a dispersant when dispersing the color material. The type of the dispersant is not particularly limited, but a polymer dispersant is preferably used, and examples of the polymer dispersant include Solsperse series manufactured by Zeneca. Moreover, it is also possible to use a synergist according to various pigments as a dispersion aid. These dispersants and dispersion aids are preferably added in an amount of 1 to 50 parts by mass with respect to 100 parts by mass of the coloring material of the present invention.

  The coloring material may be added directly to the ink composition of the present invention, but may be added in advance to a dispersion medium such as a solvent or a polymerizable compound according to the present invention in order to improve dispersibility. In order to avoid the deterioration of the solvent resistance when the solvent remains in the cured image and the problem of VOC (Volatile Organic Compound) of the remaining solvent, the coloring material is added to the polymerizable compound of the present invention. It is preferable to do. Further, as the polymerizable compound to be used, it is preferable in view of dispersion suitability to select a monomer having the lowest viscosity.

The average particle diameter of the color material particles of the present invention is, for example, 0.08 to 0.5 μm, preferably 0.1 to 0.45 μm, and more preferably 0.15 to 0.4 μm. . The maximum particle size of the color material is, for example, 0.3 to 10 μm, preferably 0.3 to 3 μm. It is appropriate to select the pigment, the dispersant, the dispersion medium, the dispersion conditions, and the filtration conditions so that the maximum particle size is obtained. 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.
In the present invention, when a coloring material is added, it is appropriate to contain, for example, 1 to 10% by mass, preferably 2 to 6% by mass with respect to the total amount of ink composition substances.

(1-7) Other components Other components can be added to the ink composition of the present invention as required. Examples of other components include a polymerization inhibitor and a solvent.
A polymerization inhibitor may be added from the viewpoint of enhancing the storage stability. In addition, the ink composition of the present invention is preferably ejected by heating and lowering the viscosity in the range of 40 to 80 ° C. In order to prevent clogging of the head due to thermal polymerization, it is preferable to add a polymerization inhibitor. The polymerization inhibitor is preferably added in an amount of 200 to 20000 ppm based on the total amount of the ink composition of the present invention. Examples of the polymerization inhibitor include hydroquinone, benzoquinone, p-methoxyphenol, TEMPO, TEMPOL, and cuperon Al.

The ink composition of the present invention preferably contains no solvent from the viewpoint of solvent resistance and VOC. However, in order to improve the adhesion to the recording medium, a very small amount of organic matter is used as long as the above problem does not occur. It is also effective to add a solvent.
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, the amount of the solvent used is preferably from 0.1 to 5% by mass, more preferably from 0.1 to 3% by mass, based on the entire ink composition.
In order to further increase the curing sensitivity, a radical polymerizable compound and a radical polymerization initiator may be used in combination, that is, a radical / cation hybrid type curable ink may be used.

  In addition to this, a known compound can be added to the ink composition of the present invention as necessary. For example, surfactants, leveling additives, matting agents, polyester resins for adjusting film properties, polyurethane resins, vinyl resins, acrylic resins, rubber resins, waxes and the like are appropriately selected and added. be able to. In order to improve the adhesion to a recording medium such as polyolefin or PET, it is also preferable to contain a tackifier that does not inhibit the polymerization. Specifically, a high molecular weight adhesive polymer described in JP-A-2001-49200, pages 5 to 6 (for example, (meth) acrylic acid and an alcohol having an alkyl group having 1 to 20 carbon atoms). An ester, a copolymer of (meth) acrylic acid and an alicyclic alcohol having 3 to 14 carbon atoms, a copolymer of an ester of (meth) acrylic acid and an aromatic alcohol having 6 to 14 carbon atoms), and polymerizability. And low molecular weight tackifying resins having an unsaturated bond.

(1-8) Properties of Ink Composition The ink composition for ink jet recording has a viscosity of, for example, a temperature at the time of ejection (for example, 40 to 80 ° C., preferably 25 to 30 ° C.) in consideration of ejection properties. 7 to 30 mPa · s, preferably 7 to 20 mPa · s. For example, the viscosity of the ink composition of the present invention at room temperature (25 to 30 ° C.) is 35 to 500 mPa · s, preferably 35 to 200 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. By setting the viscosity at room temperature high, even when a porous recording medium is used, ink penetration into the recording medium can be avoided, and uncured monomers 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.

  The surface tension of the ink composition for inkjet recording of the present invention is, for example, 20 to 30 mN / m, 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.

(2) Inkjet recording method and apparatus An inkjet recording method and an inkjet recording apparatus that can be suitably employed in the present invention will be described below.
(2-1) Inkjet recording method The present invention is a method in which the ink composition for inkjet recording is jetted onto a recording medium, the ink landed on the support is irradiated with radiation, and the ink composition is cured. A method for forming an image is provided. That is, the present invention
(a) applying the ink composition onto a recording medium;
(b) The ink composition has a peak wavelength of 200 to 600 nm, preferably 300 to 450 nm, more preferably 350 to 420 nm, and is 2000 mJ / cm ² or less, preferably 10 to 2000 mJ / cm ² . more preferably, more preferably 20~1000mJ / cm ^2, a step of curing the ink composition by irradiation at an output of 50 to 800 mJ / cm ^2; and by (c) cured ink composition onto a recording medium An image is formed.

  The recording medium is not particularly limited, and papers such as ordinary non-coated paper and coated paper, various non-absorbing resin materials used for so-called soft packaging, or resin films obtained by forming them into a film shape are used. 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 a recording medium material include polycarbonate, acrylic resin, ABS, polyacetal, PVA, and rubbers. Metals and glasses can also be used as the recording medium.

  In the ink composition of the present invention, when a material with low thermal shrinkage at the time of curing is selected, the adhesive property between the cured ink composition and the recording medium is excellent. Films that tend to curl and deform, such as heat-shrinkable PET film, OPS film, OPP film, ONy film, PVC film, etc., have the advantage that a high-definition image can be formed.

[Example of a method for ejecting and landing an ink composition]
As a method for ejecting and landing an ink composition on a recording medium, an ink jet method in which dedicated ink is ejected as fine droplets from a nozzle and adhered to a sheet is preferable. Ink jet heads include a bubble jet (registered trademark) method that generates bubbles by applying a voltage to a heater and pushes ink, a thermal ink jet method, and a piezo element method that pushes ink by vibration of a piezo element. The ink composition can be used in any of these systems.

Further, the ink jet recording method of the present invention will be described by taking as an example a method for preparing a lithographic printing plate including injecting an ink composition onto the lithographic printing plate to form an image.
The lithographic printing plate of the present invention has a hydrophilic support and a hydrophobic region (image) formed on the hydrophilic support using the ink composition of the present invention. This lithographic printing plate production method comprises the following steps:
(1) a step of ejecting the ink composition of the present invention onto the hydrophilic support; and
(2) Radiation is applied to the surface of the hydrophilic support on which the ink has been ejected to cure the ink, thereby forming a hydrophobic region (image) formed by curing the ink on the hydrophilic support. And a process.

(2-1-1) Lithographic printing plate Here, the lithographic printing plate has a hydrophilic support and an image formed on the support.
Conventionally, so-called PS plates having a configuration in which a lipophilic photosensitive resin layer is provided on a hydrophilic support have been widely used as lithographic printing plates. As a method for producing the PS plate, a desired printing plate is usually obtained by performing mask exposure (surface exposure) through a lith film and then dissolving and removing the non-exposed portion. However, in recent years, digitization technology for electronically processing, storing, and outputting image information using a computer has become widespread, and a new image output method corresponding to that has come to be demanded. In particular, Computer-to-Plate (CTP) technology has been developed that scans highly-preferred light such as laser light according to digitized image information without using a lith film, and directly produces printing plates. Yes.

  As a method for obtaining a lithographic printing plate that enables such scanning exposure, a method of directly producing a lithographic printing plate with an ink composition can be mentioned. This is because ink is ejected onto a support, preferably a hydrophilic support, by an ink jet method or the like, and exposed to radiation, whereby a portion of the ink composition is exposed to form a desired image (preferably hydrophobic). A printing plate having a sex image) is obtained. An ink composition suitable for such a system is the ink composition of the present invention.

  The support (recording medium) on which the ink composition of the present invention is ejected is not particularly limited as long as it is a dimensionally stable plate-like support. The support is preferably a hydrophilic support. For example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate) Cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), paper or plastic film on which the above-mentioned metal is laminated or deposited. Preferable supports include 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 foreign elements 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 mass 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 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 roughened aluminum plate is subjected to an alkali etching treatment using an aqueous solution of potassium hydroxide, sodium hydroxide or the like, if necessary, and 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 mass 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 lithographic printing plate can be obtained.

  As the support used in the present invention, the substrate having the above-mentioned surface treatment and having an anodized film may be used as it is, but for further improvement in adhesion to the upper layer, hydrophilicity, resistance to contamination, heat insulation and the like. If necessary, the surface of the anodized film described in JP-A-2001-253181 and JP-A-2001-322365 may be enlarged or sealed, and immersed in an aqueous solution containing a hydrophilic compound. A hydrophilic treatment or the like can be appropriately selected and performed. Of course, the large treatment and the sealing treatment are not limited to those described above, and any conventionally known methods 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. Each will be described below.

<Sealing treatment with an aqueous solution containing an inorganic fluorine compound>
As the inorganic fluorine compound used for the sealing treatment with an aqueous solution containing an inorganic fluorine compound, a metal fluoride is preferably exemplified.
Specifically, for example, sodium fluoride, potassium fluoride, calcium fluoride, magnesium fluoride, sodium fluoride zirconate, potassium fluoride zirconate, sodium fluoride titanate, potassium fluoride titanate, zircon fluoride Ammonium acid, ammonium fluoride titanate, potassium fluoride titanate, zirconate fluoride, titanate fluoride, hexafluorosilicic acid, nickel fluoride, iron fluoride, phosphor fluoride, ammonium fluoride phosphate It is done. Among these, sodium fluorinated zirconate, sodium fluorinated titanate, fluorinated zirconic acid, and fluorinated titanic acid are preferable.

The concentration of the inorganic fluorine compound in the aqueous solution is preferably 0.01% by mass or more, more preferably 0.05% by mass or more, from the viewpoint of sufficiently sealing the micropores of the anodized film. Further, in terms of stain resistance, it is preferably 1% by mass or less, and more preferably 0.5% by mass or less.
It is preferable that the aqueous solution containing an inorganic fluorine compound further contains a phosphate compound. When the phosphate compound is contained, the hydrophilicity of the surface of the anodized film is improved, so that the on-press developability and stain resistance can be improved.

Suitable examples of the phosphate compound include phosphates of metals such as alkali metals and alkaline earth metals.
Specifically, for example, zinc phosphate, aluminum phosphate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, monoammonium phosphate, monopotassium phosphate, monosodium phosphate, dihydrogen phosphate Potassium, dipotassium hydrogen phosphate, calcium phosphate, sodium ammonium hydrogen phosphate, magnesium hydrogen phosphate, magnesium phosphate, ferrous phosphate, ferric phosphate, sodium dihydrogen phosphate, sodium phosphate, hydrogen phosphate Disodium, lead phosphate, diammonium phosphate, calcium dihydrogen phosphate, lithium phosphate, phosphotungstic acid, ammonium phosphotungstate, sodium phosphotungstate, ammonium phosphomolybdate, sodium phosphomolybdate, sodium phosphite , Tripolyphosphate Potassium, and sodium pyrophosphate. Of these, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate are preferable.

The combination of the inorganic fluorine compound and the phosphate compound is not particularly limited, but the aqueous solution contains at least sodium zirconate fluoride as the inorganic fluorine compound and contains at least sodium dihydrogen phosphate as the phosphate compound. Is preferred.
The concentration of the phosphate compound in the aqueous solution is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, in terms of improvement in on-press developability and stain resistance. Further, in terms of solubility, the content is preferably 20% by mass or less, and more preferably 5% by mass or less.

The ratio of each compound in the aqueous solution is not particularly limited, but the mass ratio of the inorganic fluorine compound and the phosphate compound is preferably 1/200 to 10/1, and preferably 1/30 to 2/1. Is more preferable.
The temperature of the aqueous solution is preferably 20 ° C. or higher, more preferably 40 ° C. or higher, preferably 100 ° C. or lower, more preferably 80 ° C. or lower.
The aqueous solution preferably has a pH of 1 or more, more preferably has a pH of 2 or more, preferably has a pH of 11 or less, and more preferably has a pH of 5 or less.

The method for sealing with an aqueous solution containing an inorganic fluorine compound is not particularly limited, and examples thereof include an immersion method and a spray method. These may be used alone or a plurality of times, or may be used in combination of two or more.
Of these, the dipping method is preferred. When the treatment is performed using the dipping method, the treatment time is preferably 1 second or longer, more preferably 3 seconds or longer, and preferably 100 seconds or shorter, and 20 seconds or shorter. More preferred.

<Sealing treatment with water vapor>
Examples of the sealing treatment with water vapor include a method in which pressurized or normal-pressure water vapor is brought into contact with the anodized film continuously or discontinuously.
The temperature of the water vapor is preferably 80 ° C. or higher, more preferably 95 ° C. or higher, and preferably 105 ° C. or lower.
The water vapor pressure is preferably in the range (1.008 × 10 ^{5 to} 1.043 × 10 ⁵ Pa) from (atmospheric pressure−50 mmAq) to (atmospheric pressure + 300 mmAq).
Further, the time for which the water vapor is contacted is preferably 1 second or longer, more preferably 3 seconds or longer, 100 seconds or shorter, more preferably 20 seconds or shorter.

<Sealing treatment with hot water>
Examples of the sealing treatment with water vapor include a method in which an aluminum plate on which an anodized film is formed is immersed in hot water.
The hot water may contain an inorganic salt (for example, phosphate) or an organic salt.
The temperature of the hot water is preferably 80 ° C. or higher, more preferably 95 ° C. or higher, and preferably 100 ° C. or lower.
Further, the time of immersion in hot water is preferably 1 second or longer, more preferably 3 seconds or longer, more preferably 100 seconds or shorter, and even more preferably 20 seconds or shorter.

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 polyvinyl phosphonic 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.

(2-1-2) Step of ejecting the ink composition onto the hydrophilic support When the ink composition of the present invention is ejected onto the surface of the hydrophilic support, the ink composition is heated at 40 to 80 ° C. Preferably, the ink composition is ejected after being heated to 25 to 30 ° C. to lower the viscosity of the ink composition to 7 to 30 mPa · s, preferably 7 to 20 mPa · s. In particular, when an ink composition having an ink viscosity of 35 to 500 mPa · s at 25 ° C. is used, a great effect can be obtained. By using this method, high injection stability can be realized. A radiation curable ink composition such as the ink composition of the present invention generally has a higher viscosity than water-based inks used in ordinary ink-jet recording ink compositions, and therefore has a large viscosity variation due to temperature variations during printing. The ink viscosity fluctuation has a great influence on the change in the droplet size and the change in the ejection speed of the droplets, thereby causing the deterioration of the image quality. Therefore, it is necessary to keep the temperature of ink at the time of printing as constant as possible. Therefore, it is appropriate that the control range of the temperature of the present invention is the set temperature ± 5 ° C., preferably the set temperature ± 2 ° C., more preferably the set temperature ± 1 ° C.

(2-1-3) Step of curing the ink by irradiating the hydrophilic support on which the ink has been ejected The ink ejected on the surface of the hydrophilic support is cured by irradiating with the radiation. To do. This is because the sensitizing dye in the polymerization initiation system contained in the ink composition of the present invention absorbs radiation to be in an excited state, and the polymerization initiator is decomposed by contact with the polymerization initiator in the polymerization initiation system. This is because the polymerizable compound is cured by radical polymerization.

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 radiation is, for example, 200 to 600 nm, preferably 300 to 450 nm, more preferably 350 to 450 nm, depending on the absorption characteristics of the sensitizing dye. In addition, the polymerization initiation system of the present invention has sufficient sensitivity even with low output radiation. Thus, the output of radiation, for example, 2000 mJ / cm ² or less, preferably, 10 to 2000 mJ / cm ^2, more preferably, 20~1000mJ / cm ^2, more preferably, irradiation energy of 50 to 800 mJ / cm ² It is appropriate to be. In addition, it is appropriate that the radiation is irradiated at an exposure surface illuminance of, for example, 10 to 2000 mW / cm ² , preferably 20 to 1000 mW / cm ² .

The ink composition of the present invention is appropriately irradiated with such radiation for, for example, 0.01 to 120 seconds, preferably 0.1 to 90 seconds.
Radiation irradiation conditions and a basic irradiation method are disclosed in JP-A-60-132767. Specifically, the light source is provided on both sides of the head unit including the ink ejection device, and the head unit and the light source are scanned by a so-called shuttle method. Irradiation of radiation takes a certain time (for example, 0.01 to 0.5 seconds, preferably 0.01 to 0.3 seconds, more preferably 0.01 to 0.15 seconds) after ink landing. Will be done.

  In this way, by controlling the time from ink landing to irradiation to an extremely short time, it is possible to prevent the ink that has landed on the recording medium from spreading before curing. Further, since the ink can be exposed to a porous recording medium before the ink penetrates to a deep part where the light source does not reach, residual unreacted monomer can be suppressed, and as a result, odor can be reduced. .

  Further, the curing may be 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.

By adopting the ink jet recording method as described above, the dot diameter of the landed ink can be kept constant even on various recording media having different surface wettability, and the image quality is improved. In addition, in order to obtain a color image, it is preferable to superimpose in order from the color with the lowest brightness. By superimposing the inks in order of low lightness, it becomes easy for the irradiation line to reach the lower ink, and good curing sensitivity, reduction of residual monomers, reduction of odor, and improvement of adhesion can be expected. 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.
In this way, the ink composition of the present invention is cured by irradiation with radiation to form a hydrophobic image on the surface of the hydrophilic support.

(2-2) Inkjet recording apparatus The inkjet recording apparatus used in the present invention is not particularly limited, and a commercially available inkjet recording apparatus can be used. That is, in the present invention, recording can be performed on a recording medium using a commercially available inkjet recording apparatus.
The ink jet recording apparatus of the present invention includes, for example, an ink supply system, a temperature sensor, and a 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 4000 × 4000 dpi, preferably 400 × 400 to 1600 × 1600 dpi, and more preferably 720 × 720 dpi. It can drive so that it can inject with the resolution of. 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 in the vicinity of 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 a 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 ultraviolet light curable ink jets. 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.

  In addition, a light emitting diode (LED) and a laser diode (LD) can be used as a 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 launched 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 radiation centered between 300 nm and 370 nm. Other ultraviolet LEDs are also available and can emit radiation in different ultraviolet bands. Particularly preferred radiation sources in the present invention are UV-LEDs, and particularly preferred are UV-LEDs having a peak wavelength in the range of 350 to 420 nm.

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 the filter. Prepared by filtration.

(Yellow pigment dispersion 1)
C. I. Pigment Yellow 12 10 parts by mass Polymer dispersing agent (Solsperse series manufactured by Zeneca) 5 parts by mass OXT-221 (Oxetane compound: manufactured by Toagosei Co., Ltd.) 85 parts by mass (magenta pigment dispersion 1)
C. I. Pigment Red 57: 1 15 parts by weight Polymer dispersant (Solsperse series manufactured by Zeneca) 5 parts by weight OXT-221 (Oxetane compound: manufactured by Toagosei Co., Ltd.) 80 parts by weight (cyan pigment dispersion 1)
C. I. Pigment Blue 15: 3 20 parts by mass Polymer dispersing agent (Solsperse series manufactured by Zeneca) 5 parts by mass OXT-221 (Oxetane compound: manufactured by Toagosei Co., Ltd.) 75 parts by mass (Black pigment dispersion 1)
C. I. Pigment Black 7 20 parts by mass Polymer dispersant (Solsperse series manufactured by Zeneca) 5 parts by mass OXT-221 (Oxetane compound: manufactured by Toagosei Co., Ltd.) 75 parts by mass

<Preparation of ink>
Each color ink was prepared using each of the dispersions 1 prepared above according to the method described below.

  The inclusion compound (A) of the present invention can be synthesized using phthaloyl chloride and a corresponding diamine.

(Yellow ink 1)
(A) Cationic polymerizable compound
Celoxide 2021 (epoxy compound: Daicel UCB Co., Ltd. 35g
OXT-221 (Oxetane compound: manufactured by Toa Gosei Co., Ltd.) 55 g
(B) Photopolymerization initiator Initiator 1 5 g
(C) the inclusion compound (A) of the present invention 1.5 g
(D) Color material (pigment dispersion)
Yellow pigment dispersion 1 5g

(Magenta ink 1)
(A) Cationic polymerizable compound
Celoxide 2021 (epoxy compound: Daicel UCB Co., Ltd. 35g
OXT-221 (Oxetane compound: manufactured by Toa Gosei Co., Ltd.) 55 g
(B) Photopolymerization initiator Initiator 1 5 g
(C) the inclusion compound (A) of the present invention 1.5 g
(D) Color material (pigment dispersion)
Magenta pigment dispersion 1 5g

(Cyan ink 1)
(A) Cationic polymerizable compound
Celoxide 2021 (epoxy compound: Daicel UCB Co., Ltd. 35g
OXT-221 (Oxetane compound: manufactured by Toa Gosei Co., Ltd.) 55 g
(B) Photopolymerization initiator Initiator 1 5 g
(C) the inclusion compound (A) of the present invention 1.5 g
(D) Color material (pigment dispersion)
Cyan pigment dispersion 1 5g

(Black ink 1)
(A) Cationic polymerizable compound
Celoxide 2021 (epoxy compound: Daicel UCB Co., Ltd. 35g
OXT-221 (Oxetane compound: manufactured by Toa Gosei Co., Ltd.) 55 g
(B) Photopolymerization initiator Initiator 1 5 g
(C) the inclusion compound (A) of the present invention 1.5 g
(D) Color material (pigment dispersion)
Black pigment dispersion 1 5g

<Inkjet image recording> (Evaluation of multicolor images)
Next, recording on a recording medium was performed using a commercially available inkjet recording apparatus having a piezo inkjet nozzle. The ink supply system was composed of an original tank, a supply pipe, 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 ink jet head, respectively, and temperature control was performed so that the nozzle portions were always 70 ° 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 light was condensed to an exposure surface illuminance of 100 mW / cm ² , and the exposure system, main scanning speed, and ejection frequency were adjusted so that irradiation started 0.1 seconds after ink landed 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 was not cracked even when it was bent, and there was no problem in the adhesion test by peeling the cello tape (registered trademark). Also, the color of the recorded ink did not change compared to the color of the ink before curing.

Examples 2-5
<Preparation of ink>
Magenta inks 2-5 were prepared according to the method described below.

  The clathrate compounds (B) and (C) of the present invention and the comparative clathrate compound (D) can be synthesized using, for example, the method described in JACS, 113, 22, (1991), pages 8229-8242. it can.

(Magenta ink 2) Example 2
(A) Cationic polymerizable compound
Celoxide 2021 (epoxy compound: Daicel UCB Co., Ltd. 35g
OXT-221 (Oxetane compound: manufactured by Toa Gosei Co., Ltd.) 55 g
(B) Photopolymerization initiator Initiator 1 5 g
-(C) 1.5g of inclusion compound of the present invention (B)
(D) Color material (pigment dispersion)
Magenta pigment dispersion 1 5g

(Magenta ink 3) Example 3
(A) Cationic polymerizable compound
Celoxide 2021 (epoxy compound: Daicel UCB Co., Ltd. 35g
OXT-221 (Oxetane compound: manufactured by Toa Gosei Co., Ltd.) 55 g
(B) Photopolymerization initiator Initiator 1 5 g
(C) the inclusion compound (C) of the present invention 1.5 g
(D) Color material (pigment dispersion)
Magenta pigment dispersion 1 5g

(Magenta ink 4, comparative example 1)
(A) Cationic polymerizable compound
Celoxide 2021 (epoxy compound: Daicel UCB Co., Ltd. 35g
OXT-221 (Oxetane compound: manufactured by Toa Gosei Co., Ltd.) 55 g
(B) Photopolymerization initiator Initiator 1 5 g
(D) Color material (pigment dispersion)
Magenta pigment dispersion 1 5g

(Magenta ink 5, comparative example 2)
(A) Cationic polymerizable compound
Celoxide 2021 (epoxy compound: Daicel UCB Co., Ltd. 35g
OXT-221 (Oxetane compound: manufactured by Toa Gosei Co., Ltd.) 55 g
(B) Photopolymerization initiator Initiator 1 5 g
(C) Comparative inclusion compound (D) 1.5 g
(D) Color material (pigment dispersion)
Magenta pigment dispersion 1 5g

  In the ink compositions prepared in the above examples and comparative examples, the ink viscosity at the ejection temperature is 7 to 20 mPa.s. It was within the range of s.

[Inkjet image recording] (single color image evaluation)
Using the magenta inks 2 to 8 prepared as described above and the magenta ink 1 prepared in Example 1, magenta image printing was performed in the same manner as the method described in Example 1.

1． Evaluation of Inkjet Image Next, for each formed image, the sensitivity required for curing, permeability in commercially available recycled paper, ink bleeding on a grained aluminum support, adhesion, and resistance according to the method described below. The printability and storage stability were evaluated.

2. Measurement of Curing Sensitivity The amount of exposure energy (mJ / cm ² ) that eliminates stickiness on the image surface after UV irradiation was defined as curing sensitivity. The smaller the value, the higher the sensitivity.

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

4). Permeability evaluation with respect to commercially available recycled paper For images printed on commercially available recycled paper, the 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

5. Evaluation of Ink Bleeding on Grained Aluminum Support An image printed on a grained aluminum support was evaluated for ink bleeding according to the following criteria.
○: No blur between adjacent dots Δ: Slightly blur dots ×: Dot blurs and the image is clearly blurred

6). Evaluation of adhesion on grained aluminum support)
With respect to the print image created above, a sample that does not scratch the print surface at all, and in accordance with JISK 5400, 11 cuts are made on the print surface at 1 mm intervals vertically and horizontally, and a 1 mm square grid 100 is formed. Individual samples were prepared, and a cellophane tape was applied to each printing surface. The sample was peeled off quickly at an angle of 90 degrees, and the state of the printed image remaining without peeling or the grid pattern was evaluated according to the following criteria.
○: No peeling of the printed image is observed even in the cross cut test. Δ: Some peeling of the ink is recognized in the cross cut test, but almost no peeling is observed unless the ink surface is scratched. Easy to peel off with cello tape (registered trademark)

7. Color change of ink before and after curing ○: No color change observed visually Δ: Slight color change observed visually ×: Color changed clearly visually

[Evaluation as a lithographic 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.
a. Evaluation of Image A lithographic printing plate produced from the ink composition of the present invention was put on a Heidel KOR-D machine, and ink (VALUES-G red for sheet-fed paper, manufactured by Dainippon Ink Co., Ltd.) and fountain solution (Ecolity 2, Fuji) Photo Film Co., Ltd.) was supplied for printing. The printed matter after printing 100 sheets was visually evaluated according to the following criteria.
◯: An image with no white spots in the image area and no stain in the non-image area was obtained.
Δ: Slight white spots in the image area and / or slight stains were observed in the non-image area.
X: White spots in the image area and / or stains in the non-image area were observed, and there was a problem in practical use.
b. Evaluation of printing durability Printing was continued as it was, and the relative number of finished sheets was compared as an index of printing durability (Comparative Example 3 was set to 100). A larger numerical value is preferable because it has a higher printing durability.
These evaluation results are shown in Table 2.

As can be seen from the results of Examples 1 to 3 in Table 2, when the ink composition of the present invention is used, it does not show permeability to commercially available recycled paper, and the bleeding and adhesion on the aluminum support are good. Met. The ink composition of the present invention had high curing sensitivity and ink storage stability, and no color change was observed before and after curing. Further, the image of the lithographic printing plate using the ink composition of the present invention was also good, and high printing durability was seen.
On the other hand, when the compound of the present invention was not used (Comparative Example 1), it penetrated into commercially available recycled paper, and bleeding on the aluminum support was also observed. Further, the ink storage stability was very low, and a clear color change was visually observed before and after curing. Further, when the comparative compound (D) having the same skeleton as the compounds (B) and (C) of the present invention and having the adjacent carbon atom of the nitrogen atom substituted only with hydrogen (Comparative Example 2) is compared with Comparative Example 1. The storage stability was slightly improved, but the color change was clearly confirmed before and after curing.

Claims (9)

(A) a polymerizable compound, (b) a photopolymerization initiator, and (c) an inclusion compound having at least one atom selected from a nitrogen, oxygen or sulfur atom, wherein the carbon atom adjacent to the atom is An ink composition comprising an inclusion compound which is a secondary or tertiary carbon atom. 2. The ink composition according to claim 1, wherein the inclusion compound (c) is an inclusion compound having at least one partial structure represented by the following general formula (I) in the molecule.

(In the formula, X represents NH or NR, oxygen, or a sulfur atom. R ¹ and R ² each independently represents a hydrogen atom or a substituted or unsubstituted hydrocarbon group, and R ¹ and R ² are (At least one is a substituted or unsubstituted hydrocarbon group, and R is a substituted or unsubstituted alkyl group.) The ink composition according to claim 1, further comprising (d) a color material. The ink composition according to claim 3, wherein the color material (d) is a pigment or an oil-soluble dye. The ink composition according to any one of claims 1 to 4, which is for inkjet recording. A step of jetting and landing the ink composition according to any one of claims 1 to 5 on a recording medium, and a step of irradiating the ink composition with radiation to cure the ink composition. An inkjet recording method. A printed matter obtained by ejecting and landing the ink composition according to any one of claims 1 to 5 on a recording medium and then irradiating the ink composition to cure the ink composition. A hydrophobic region is formed by spraying the ink composition according to any one of claims 1 to 5 onto a hydrophilic support, landing, and then irradiating the ink to cure the ink. A method for producing a lithographic printing plate, comprising: It was formed by ejecting the ink composition according to any one of claims 1 to 5 on a hydrophilic support, landing and then curing the ink composition by irradiation with radiation. A lithographic printing plate having a hydrophobic region.