JP2006274204A - Ink composition, and image-forming method and recorded matter obtained using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink composition having heat resistance and an excellent wetting property to a support, and an image-forming method capable of stably forming a fast image of high image qualities and recorded matter using the ink composition. <P>SOLUTION: The ink composition comprises a polymerizable compound, a photopolymerization initiator, and a homopolymer of a monomer represented by general formula (1). The image-forming method comprises using the same. The recorded matter is obtained using the same. In general formula, n is an integer of 2-14; R is a hydrogen atom or a 1-10C alkyl group; and L is a single bond or a bivalent organic group containing at least one atom selected from among an oxygen atom, a nitrogen atom, a sulfur atom and a carbon atom. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  As an ink having fading resistance and the like, a UV ink that is cured by irradiation with ultraviolet rays (UV) and has a UV light shielding property is known (for example, see Patent Document 1). For such curing using ink, a system utilizing radical polymerization of a monomer component is widely used, and an acrylate monomer or the like is generally used as the monomer component (for example, Patent Document 2). To 4).

However, these UV inks have been required to be improved because they have insufficient wettability to the surface when discharged onto various supports. In response to such a demand, for example, an ink composition that defines surface tension and viscosity and further uses a fluorine-based surfactant has been proposed (for example, see Patent Document 5). However, even with such an ink composition, the wettability with respect to the support is not yet sufficient, and the heat resistance during storage of the ink composition is reduced by adding a fluorosurfactant. There was also.
JP 2003-221528 A JP 2003-246818 A JP 2003-292855 A Japanese Patent Laid-Open No. 9-183927 JP 2004-51881 A

As described above, when an ink composition that is polymerized and cured when exposed to light or the like increases the wettability to the support by adding a surfactant or the like, the heat resistance during storage is lowered. For this reason, it becomes easy to receive the influence of a heat | fever and may raise | generate a thermopolymerization reaction with time and may gelatinize.
When the thickening and curing proceed due to gelation or the like, for example, when used for ink jet recording, there is a problem that a predetermined amount cannot be ejected from the nozzle, and it becomes difficult to form an image with high quality.

  In order to solve the above-mentioned problems, the present invention has an ink composition having heat resistance and excellent wettability with respect to a support, and a stable and high-quality image formed using the ink composition. An object of the present invention is to provide an image forming method and a recorded matter that can be recorded.

The problems of the present invention are solved by the following means.
<1> An ink composition comprising a polymerizable compound, a photopolymerization initiator, and a homopolymer of a monomer represented by the following general formula (1).

〔一般式（１）中、ｎは２〜１４の整数を表す。Ｒは水素原子または炭素数１〜１０のアルキル基を表す。Ｌは、単結合、又は、酸素原子、窒素原子、硫黄原子及び炭素原子から選ばれる少なくとも１つの原子を含む二価の有機基を表す。〕

[In general formula (1), n represents the integer of 2-14. R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. L represents a single bond or a divalent organic group containing at least one atom selected from an oxygen atom, a nitrogen atom, a sulfur atom and a carbon atom. ]

  <2> The ink composition according to <1>, wherein the homopolymer has a weight average molecular weight (MW) of 3000 or more.

  <3> The ink composition according to <1> or <2>, wherein the polymerizable compound includes at least one oxetane group-containing compound and at least one oxirane group-containing compound. .

  <4> The polymerizable compound includes at least one trifunctional or higher (meth) acrylate and at least one selected from monofunctional (meth) acrylate and bifunctional (meth) acrylate. <1> to <3>.

  <5> The ink composition according to <1> to <4>, further including a colorant.

  <6> The ink composition according to <5>, wherein the colorant is a pigment or an oil-soluble dye.

  <7> The ink composition according to <6>, wherein the oil-soluble dye has an oxidation potential nobler than 1.0 V (vs SCE).

  <8> The ink composition according to <1> to <7>, which is used for ink jet recording.

  <9> An image recording step of recording an image on a recording material using the ink composition of <1> to <8>, and an active energy ray on the image recorded on the recording material in the image recording step And an image curing step of irradiating and curing.

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

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

  According to the present invention, an ink composition having heat resistance and excellent wettability to a support, and an image forming method capable of stably forming a robust and high-quality image using the ink composition And records can be provided.

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

<Ink composition>
The ink composition of the present invention comprises a polymerizable compound, a photopolymerization initiator, and a homopolymer of a monomer represented by the following general formula (1).

〔一般式（１）中、ｎは２〜１４の整数を表す。Ｒは水素原子または炭素数１〜１０のアルキル基を表す。Ｌは、単結合、又は、酸素原子、窒素原子、硫黄原子及び炭素原子から選ばれる少なくとも１つの原子を含む二価の有機基を表す。〕

[In general formula (1), n represents the integer of 2-14. R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. L represents a single bond or a divalent organic group containing at least one atom selected from an oxygen atom, a nitrogen atom, a sulfur atom and a carbon atom. ]

  The ink composition of the present invention has a specific structure and has an effect as a fluorine-based surfactant, and is a homopolymer of the monomer represented by the general formula (1) (hereinafter referred to as “polymer in the present invention”). In some cases, for example, an ink receiving layer or the like is included on the support as well as a mere support. Including wettability to them). In addition, since the polymer in the present invention has little influence on the heat resistance during storage in the ink composition of the present invention, the ink composition of the present invention improves the wettability without deteriorating the heat resistance. be able to.

  The ink composition of the present invention is configured such that a recorded image can be cured by irradiation with an active energy ray after recording an image on a recording material. In addition, the ink composition of the present invention preferably includes a colorant in addition to the polymerizable compound, the photopolymerization initiator, and the homopolymer of the present invention. In addition, the ink composition of the present invention can be constituted using other components such as various additives as necessary.

(Polymerizable compound)
The polymerizable compound used in the present invention is not particularly limited as long as it is a compound that causes a polymerization reaction by an active species generated from a photopolymerization initiator and cures, and a radical polymerizable compound or a cationic polymerizable compound is used. be able to.
Hereinafter, the radical polymerizable compound and the cationic polymerizable compound will be described.

-Radically polymerizable compounds-
The radical polymerizable compound is a compound having an ethylenically unsaturated bond capable of radical polymerization, and may be any compound as long as it has at least one ethylenically unsaturated bond capable of radical polymerization in the molecule. , Oligomers, polymers and the like having a chemical form. Only one kind of such radically polymerizable compounds may be used, or two or more kinds thereof may be used in combination at an arbitrary ratio in order to improve desired properties. A polyfunctional compound having two or more functional groups is more preferable than a monofunctional compound. More preferably, two or more polyfunctional compounds are used in combination for controlling performance such as reactivity and physical properties.

  In the ink composition of the present invention, (meth) acrylate can be suitably used as the radical polymerizable compound. Examples of the (meth) acrylate include the following compounds. In the present invention, among the following polymerizable compounds, (a) at least one trifunctional or higher (meth) acrylate and (b) monofunctional (meth) acrylate and bifunctional (meth) acrylate are selected. It is preferable to include at least one kind from the viewpoints of adjusting viscosity, adjusting crosslinking density, and controlling physical properties after curing (strength, adhesiveness, etc.).

  Specific examples of the monofunctional (meth) acrylate include hexyl (meth) acrylate, 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-ethylhexylglycol (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 (meth) acrylate, 4- Butylphenyl (meth) acrylate, phenyl (meth) acrylate, 2,4,5-tetramethylphenyl (meth) acrylate, 4-chlorophenyl (meth) acrylate, phenoxymethyl (meth) acrylate, phenoxyethyl (meth) acrylate Rate, glycidyl (meth) acrylate, glycidyl Giro carboxybutyl (meth) acrylate, glycidyl Giro carboxyethyl (meth) acrylate, glycidyl Giro hydroxypropyl (meth) acrylate, morpholino (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, diethylaminopropyl (meth) acrylate, tri Methoxysilylpropyl (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 (meth) acrylate, 2-methacryloyloxytyl succinic acid, 2-methacryloyloxyhexahydrophthalic acid, 2-methacryloyloxyethyl-2- Hydroxypropyl phthalate, butoxydiethylene glycol (meth) acrylate, trifluoroethyl (meta Acrylate, perfluorooctylethyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, ethylene oxide modified phenol (meth) acrylate, ethylene oxide modified cresol (meth) acrylate, ethylene oxide modified nonylphenol (meth) acrylate , Polyethylene oxide modified nonylphenol (meth) acrylate, ethylene oxide modified-2-ethylhexyl (meth) acrylate, carbitol (meth) acrylate, oligoester (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, methyl ( (Meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate Examples include relate, allyl (meth) acrylate, glycidyl (meth) acrylate, benzyl (meth) acrylate, and dimethylaminomethyl (meth) acrylate.

  Specific examples of the bifunctional (meth) acrylate include dipropylene glycol di (meth) acrylate, dimethylol dicyclopentane di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, and 1,6-hexane. Diol 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- Tandiol di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, ethylene oxide 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-nonanedi (meth) acrylate, propoxylated ethoxylated bisphenol A di (meth) ) Acrylate, Tricyclodecane di (meth) acrylate, Diethylene glycol di (meth) acrylate, Triethylene glycol di (meth) acrylate, Tetraethylene Glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate.

  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, ethoxylated glycerin triacrylate, trimethylolpropane tri (meth) acrylate.

  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, dipentaerythritol tetra (meth) acrylate, tetramethylolmethane tetra (meth) acrylate, and the like.

  Specific examples of the pentafunctional (meth) acrylate include sorbitol penta (meth) acrylate, dipentaerythritol penta (meth) acrylate, and the like.

  Specific examples of hexafunctional (meth) acrylates include dipentaerythritol hexa (meth) acrylate, sorbitol hexa (meth) acrylate, phosphazene alkylene oxide modified hexa (meth) acrylate, caprolactone modified dipentaerythritol hexa (meth) acrylate , Etc.

  The (meth) acrylate represents that it can have both acrylate and methacrylate structures.

  Examples of radically polymerizable compounds other than those listed above include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, and their salts, esters, urethanes, Examples thereof include radical polymerizable compounds such as amides, anhydrides, acrylonitrile, styrene, various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes. Specific examples include acrylic acid derivatives such as bis (4-acryloxypolyethoxyphenyl) propane and diacetone acrylamide, methacrylic derivatives such as 2,2-bis (4-methacryloxypolyethoxyphenyl) propane, and allyl glycidyl. Derivatives of allyl compounds such as ether, diallyl phthalate, triallyl trimellitate, and the like, more specifically, Shinzo Yamashita, “Crosslinker Handbook”, (1981 Taiseisha);・ EB Curing Handbook (Raw Materials Edition) ”(1985, Polymer Publishing Society); Radtech Study Group,“ Application and Market of UV / EB Curing Technology ”, 79 pages (1989, CMC); Eiichiro Takiyama , "Polyester resin handbook", (1988, Nikkan Kogyo Shimbun) etc. Known radical polymerizable or crosslinkable monomers can be used oligomers and polymers.

-Cationically polymerizable compound-
As the cationic polymerizable compound, various known cationic polymerizable monomers known as photo cationic polymerizable monomers can be used. Examples of the cationically polymerizable monomer include JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-310937, and JP-A-2001-220526. And vinyl ether compounds, oxetane compounds, and oxirane compounds described in 1).

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

In the present invention, it is preferable that both the oxetane group-containing compound and the oxirane group-containing compound are used in combination. However, as an aspect of the combination, for example, exemplified compound (a) and exemplified compound (i) The aspect which combined and the aspect which combined exemplary compound (b) and exemplary compound (v) are especially preferable at the point which can improve light resistance more effectively.
The content of the polymerizable compound in the ink composition of the present invention is preferably 98 to 50% by mass with respect to the total mass of the ink composition from the viewpoint of sensitivity based on polymerization reactivity and the viscosity of the ink composition, and 95 -60 mass% is more preferable, More preferably, it is the range of 90-70 mass%.

(Photopolymerization initiator)
The ink composition of the present invention contains at least one photopolymerization initiator that polymerizes and cures the polymerizable compound. The photopolymerization initiator has absorption in the wavelength region of the active energy ray, and can act on the above-described polymerizable compound and accelerate polymerization and curing when exposed to the active energy ray.

  The photopolymerization initiator is a compound that generates a chemical change through the action of an active energy ray or the interaction with an electronically excited state of a sensitizing dye to generate at least one of a radical, an acid, and a base. Specifically, active radical species are generated by application of active energy rays to initiate and accelerate polymerization and curing of the polymerizable compound (ie, ink composition), and cationic species are generated by application of active energy rays. Similarly, an initiator for starting and accelerating the polymerization and curing of the polymerizable compound (that is, the ink composition) is included, and can be appropriately selected from the following polymerization initiators.

  In the present invention, “active energy rays” are active rays that generate radicals or cations from a photopolymerization initiator, and include ultraviolet rays (UV light), visible rays, γ rays, α rays, X rays, and other electron rays. . As specific light sources, for example, LD, LED, fluorescent lamp, low-pressure mercury lamp, high-pressure mercury lamp, metal halide lamp, carbon arc lamp, xenon lamp, chemical lamp, and the like can be applied. Preferred light sources include LEDs, high pressure mercury lamps, and metal halide lamps.

  As an example of a photoinitiator, what is known among those skilled in the art can be used without a restriction | limiting. Specifically, for example, Bruce M. et al. Monroe et al., Chemical Review, 93, 435 (1993). R. S. By Davidson, Journal of Photochemistry and biologic A: Chemistry, 73.81 (1993). J. et al. P. Faussier “Photoinitiated Polymerization—Theory and Applications”: Rapra Review vol. 9, Report, Rapra Technology (1998). , M.M. Tsunooka et al. , Prog. Polym. Sci. , 21, 1 (1996). Are described in the above. In addition, it is described as a chemical amplification type photoresist or a compound used for photocationic polymerization in “Organic Materials for Imaging” (see Organic Electronics Materials Research Group, Bunshin Publishing (1993), p. 187 to 192). Compounds. Further, F.R. D. Saeva, Topics in Current Chemistry, 156, 59 (1990). G. G. Maslak, Topics in Current Chemistry, 168, 1 (1993). H., et al. B. Shuster et al, JACS, 112, 6329 (1990). , I. D. F. Eaton et al, JACS, 102, 3298 (1980). A group of compounds that undergo bond oxidative or reductive cleavage through interaction with the electronically excited state of the sensitizing dye as described above.

  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 salt compound, (h) a metallocene compound, (i) an active ester compound, (j) a compound having a carbon halogen bond, and the like.

  Preferable examples of the (a) aromatic ketones include “RADIATION CURING IN POLYMER SCIENCE AND TECHNOLOGY” P. FOUASSIER J.M. F. RABEK (1993), p. And compounds having a benzophenone skeleton or a thioxanthone skeleton described in 77-117. More preferable examples of the 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, dialkoxybenzophenone described in JP-B-60-26483 Benzoin ethers described in JP-B-60-26403, JP-A-62-81345, JP-B-1-34242, US Pat. No. 4,318,791, and α described in European Patent 0284561A1. -Aminobenzophenones, p-di described in JP-A-2-211452 Dimethylaminobenzoyl) benzene, a thio-substituted aromatic ketone described in JP-A-61-194062, an acylphosphine sulfide described in JP-B-2-9597, an acylphosphine described in JP-B-2-9596, Examples thereof include thioxanthones described in JP-B-63-61950, coumarins described in JP-B-59-42864, and the like.

As the (b) aromatic onium salt compound, elements of Group V, VI and VII of the periodic table, specifically, N, P, As, Sb, Bi, O, S, Se, Te, or Aromatic onium salts of I are included. For example, European Patent No. 104143, US Pat. No. 4,837,124, Japanese Patent Laid-Open No. 2-150848, Japanese Patent Laid-Open No. 2-96514, iodonium salts, European Patent Nos. 370693, 233567, 297443, The sulfonium salts and diazonium described in the specifications of U.S. Pat. Nos. 2,974,279, 279210, and 422570, and U.S. Pat. Nos. 3,902,144, 4,933,377, 4,760013, 4,734,344, and 2,833,827 Salts (such as benzenediazonium which may have a substituent), diazonium salt resins (formaldehyde resin of diazodiphenylamine), N-alkoxypyridinium salts and the like (for example, US Pat. No. 4,743,528, JP, Sho 63-138 No. 45, JP-A-63-142345, JP-A-63-142346, and JP-B-46-42363, specifically 1-methoxy-4-phenylpyridinium tetrafluoro Preferable examples include compounds described in JP-B Nos. 52-147277, 52-14278, and 52-14279. Generates radicals and acids as active species.

  The organic peroxide (c) includes an organic compound having one or more oxygen-oxygen bonds in the molecule. Specific examples thereof include 3,3′4,4′-tetra- (t-butylperoxide. Oxycarbonyl) 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- (p Preferable examples include peroxide esters such as -isopropylcumylperoxycarbonyl) benzophenone and di-t-butyldiperoxyisophthalate.

  Examples of the (d) hexaarylbiimidazole compound 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'-tetraphenylbiimidazole, 2,2'-bis (o-methylphenyl) -4,4', 5,5'-tetraphenylbiimidazole, 2,2'-bis (o- Trifluorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole, and the like.

  Examples of the (e) ketoxime ester compound include 3-benzoyloxyiminobutan-2-one, 3-acetoxyiminobutan-2-one, 3-propionyloxyiminobutan-2-one, and 2-acetoxyimino. Pentan-3-one, 2-acetoxyimino-1-phenylpropan-1-one, 2-benzoyloxyimino-1-phenylpropan-1-one, 3-p-toluenesulfonyloxyiminobutan-2-one, 2-ethoxycarbonyloxyimino-1-phenylpropan-1-one, and the like.

  Examples of the (f) borate compound include compounds described in US Pat. Nos. 3,567,453, 4,343,891, European Patents 109,772, and 109,773. It is done.

  Examples of the (g) azinium salt compound 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 a NO bond as described in each gazette of No. is mentioned.

  Examples of the (h) metallocene compound include, for example, JP-A-59-152396, JP-A-61-151197, JP-A-63-41484, JP-A-2-249, and JP-A-2-4705. Examples thereof include titanocene compounds described in the publication and 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.

  Examples of the (i) active ester compound include, for example, the specifications of European Patent Nos. 0290750, 046083, 156153, 271851, and 0388343, U.S. Pat. Nos. 3,901,710, and 4,181,531. And nitrobenzester 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, and JP-A 64-18143, JP-A-2-245756, and JP-A-4-365048. Iminosulfonate compounds described in 1. No. 62-6223, JP-B-63-14340, and include the compounds described in each publication of JP-59-174831.

  Preferred examples of the compound (j) having a carbon halogen bond include Wakabayashi et al., Bull. Chem. Soc. Japan, 42, 2924 (1969), a compound described in British Patent No. 1388492, a compound described in JP-A-53-133428, a compound described in German Patent No. 3337024, etc. Can be mentioned.

  F.F. C. J. Schaefer et al. Org. Chem. 29, 1527 (1964), compounds described in JP-A-62-258241, compounds described in JP-A-5-281728, and the like. Examples thereof also include compounds described in German Patent No. 2641100, compounds described in German Patent No. 3333450, compounds described in German Patent No. 3021590, or compounds described in German Patent No. 3021599, and the like.

  Preferred specific examples of the compounds represented by the above (a) to (j) are listed below.

  As content in the ink composition of a photoinitiator, the range of 0.5-20 mass% is preferable with respect to the total amount of the above-mentioned polymerizable compound and photoinitiator, and 1-12 mass%. The range of is more preferable. When the content is particularly in the above range, the curing rate is high and good curability is obtained, which is effective for recording robust images. Further, the scratch resistance when the image is rubbed does not deteriorate.

(Surfactant)
The ink composition of the present invention contains a homopolymer of a monomer represented by the following general formula (1) (polymer in the present invention). The polymer in the present invention acts as a surfactant and can improve the wettability with respect to the support without reducing the heat resistance during storage of the ink composition of the present invention.

〔一般式（１）中、ｎは２〜１４の整数を表す。Ｒは水素原子または炭素数１〜１０のアルキル基を表す。Ｌは、単結合、又は、酸素原子、窒素原子、硫黄原子及び炭素原子から選ばれる少なくとも１つの原子を含む二価の有機基を表す。〕

[In general formula (1), n represents the integer of 2-14. R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. L represents a single bond or a divalent organic group containing at least one atom selected from an oxygen atom, a nitrogen atom, a sulfur atom and a carbon atom. ]

In General formula (1), n represents the integer of 2-14, Preferably it is an integer of 6-12. R is a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. Specific examples of the alkyl group having 1 to 10 carbon atoms include methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, iso-butyl group, and tert-butyl group.
L represents a single bond or a divalent organic group containing at least one atom selected from an oxygen atom, a nitrogen atom, a sulfur atom, and a carbon atom. Examples of L include a single bond, —O—, —SO ₂ —, —NH—, —SO ₂ NH—, —CH ₂ — and the like.

  As the monomer represented by the general formula (1), a monomer represented by the following general formula (1-A) is particularly preferable.

〔一般式（１−Ａ）中、ｎ及びＲは、一般式（１）におけるものと同様であり、Ｒ¹はＲと同義である。〕

[In general formula (1-A), n and R are the same as those in general formula (1), and R ¹ has the same meaning as R. ]

  Preferred specific examples of the monomer represented by the general formula (1) are shown in Table 1 below.

  The weight average molecular weight Mw of the polymer in the present invention is preferably 3000 or more, and more preferably 6000 or more. Moreover, the upper limit of the weight average molecular weight of the polymer in the present invention is not particularly limited, but is preferably 60000 or less, and more preferably 30000 or less from the viewpoint of viscosity and the like.

  The ink composition of the present invention may be used by mixing two or more polymers according to the present invention having different molecular structures and / or monomer compositions.

  As content of the polymer in this invention, 0.005-1.0 mass% is preferable with respect to the said polymeric compound, Furthermore, 0.03-1.0 mass% is preferable, 0.1-0.5 Mass% is particularly preferred. Especially this invention can fully exhibit the effect of the wettability improvement with respect to a support body even if a small amount is added.

  The ink composition of the present invention is in addition to the polymer of the present invention within a range that does not impair the effects of the present invention, that is, within a range that can improve the wettability to the support without reducing the heat resistance during storage. These known surfactants may be used in combination.

Examples of the other known surfactants include those described in JP-A Nos. 62-173463 and 62-183457. Specifically, for example, anionic surfactants such as dialkyl sulfosuccinates, alkyl naphthalene sulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene -Nonionic surfactants such as polyoxypropylene block copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. An organic fluoro compound may be used instead of the known surfactant. The organic fluoro compound is preferably hydrophobic. Examples of the organic fluoro compounds include fluorine surfactants, oily fluorine compounds (eg, fluorine oil) and solid fluorine compound resins (eg, tetrafluoroethylene resin). No. (columns 8 to 17) and those described in JP-A Nos. 62-135826.
When the known surfactant is used in combination with the polymer in the present invention, the amount of the polymer in the present invention relative to the total amount of the surfactant is preferably 30% by mass or more, more preferably 50 to 90% by mass. preferable.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  The colorant is preferably added in an amount of 0.05 to 20% by mass, more preferably 0.2 to 10% by mass, based on the total mass of the ink composition. When an oil-soluble dye is used as the colorant, the content is particularly preferably 0.2 to 6% by mass with respect to the total mass (including the solvent) of the ink composition.

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

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

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

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

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

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

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

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

In general formula (ix), A ³ and A ⁴ each independently represent —S—, —NR ⁶² —, or —NR ⁶³ —, and R ⁶² and R ⁶³ each independently represent substituted or unsubstituted. Represents an alkyl group, a substituted or unsubstituted aryl group. L ⁴ and L ⁵ 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. R ⁶⁰ and R ⁶¹ each independently represent a hydrogen atom or a monovalent nonmetallic atomic group. R ⁶⁰ and R ⁶¹ may be bonded to each other to form an aliphatic or aromatic ring.

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

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

The content of the sensitizing dye in the ink composition of the present invention is preferably 0.01 to 20% by mass, preferably 0.1 to 15% by mass with respect to the total mass of the ink composition, from the viewpoint of ink colorability. Is more preferable, and still more preferably in the range of 0.5 to 10% by mass.
The said sensitizing dye may be used individually by 1 type, and may use 2 or more types together.
The content ratio of the sensitizing dye and the photopolymerization initiator in the ink composition is a mass ratio of a / c from the viewpoint of improving the decomposition rate of the photopolymerization initiator and transmitting light. = 100-0.5 is preferable, a / c = 50-1 is more preferable, and a / c = 10-1.5 is still more preferable.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

<Image forming method and recorded matter thereof>
The image forming method of the present invention includes a step of recording an image on a recording material using the ink composition of the present invention described above (image recording step), and irradiating the recorded image with active energy rays (active rays). And a step of curing (image curing step). In the present invention, active energy rays are used in the image curing step, and after recording an image on a recording material in the image recording step, the recorded images are irradiated with active energy rays, thereby contributing to imaging. Polymerization and curing of the polymerizable compound proceeds, and it is possible to form an image that is cured well and has high fastness.

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

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

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

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

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

[Example 1]
Components of the following composition were mixed and stirred to obtain a cyan ink (1) of the present invention.
-Ethoxylated pentaerythritol hexaacrylate (SR494, manufactured by SARTOMER; polymerizable compound) ... 10.0 g
・ 1,6-hexanediol diacrylate 10.0g
(HDDA, Daiichi Kogyo Seiyaku Co., Ltd .; polymerizable compound)
・ 2,2-Dimethoxy-1,2-diphenylethane-1-one ... 0.6g
2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide
… 1.2g
(Ciba Specialty Chemicals, photopolymerization initiator)
・ The following cyan dye C-1 (colorant): 0.3 g
・ Monomer 1 homopolymer in Table 1 0.2 g
(Homopolymer in the present invention, weight average molecular weight: 8000)

[Example 2]
In Example 1, the cyan ink (2) of the present invention was obtained in the same manner as in Example 1 except that the addition amount of the homopolymer of monomer 1 in Table 1 was changed to 0.06 g.

[Example 3]
In Example 1, the same procedure as in Example 1 was used except that 0.06 g of the homopolymer of monomer 2 in Table 1 (weight average molecular weight: 15000) was used instead of the homopolymer of monomer 1 in Table 1 above. Cyan ink (3) of the present invention was obtained.

[Example 4]
In Example 1, the same procedure as in Example 1 was used except that 0.06 g of the homopolymer of monomer 3 in Table 1 (weight average molecular weight: 6000) was used instead of the homopolymer of monomer 1 in Table 1 above. A cyan ink (4) of the present invention was obtained.

[Example 5]
In Example 1, the same procedure as in Example 1 was used except that 0.06 g of the homopolymer of monomer 4 in Table 1 (weight average molecular weight: 24000) was used instead of the homopolymer of monomer 1 in Table 1 above. A cyan ink (5) of the present invention was obtained.

[Comparative Example 1]
In Example 1, a cyan ink for comparison (1) was used in the same manner as in Example 1 except that 0.2 g of “Zonyl FSN100 (manufactured by Du Pont)” was used instead of the homopolymer of monomer 1 in Table 1 above. ') Got.

[Comparative Example 2]
In Example 1, a cyan ink for comparison (2) was used in the same manner as in Example 1 except that 0.06 g of “Zonyl FSN100 (manufactured by Du Pont)” was used instead of the homopolymer of monomer 1 in Table 1. ') Got.

[Comparative Example 3]
In Example 1, a comparative cyan ink (3 ′) was obtained in the same manner as in Example 1 except that the homopolymer of monomer 1 in Table 1 was not used.

[Example 6]
Components of the following composition were mixed and stirred to obtain a magenta ink (6) of the present invention.
・ 3 ′, 4′-epoxycyclohexane) methyl-3,4-epoxycyclohexanecarboxylate… 3.0 g
(Celoxide 2021A: manufactured by Daicel UCB; polymerizable compound)
・ 3-Phenyl-3-phenoxymethyloxetane ... 17.0g
(Aron Oxetane OXT-211 manufactured by Toa Gosei Co., Ltd .; polymerizable compound)
・ Photopolymerization initiator: 0.6g
(Syracure photocuring initiator UVI-6992, manufactured by Dow Chemical Japan Co., Ltd.)
-The following magenta dye M-1 (colorant): 0.4 g
-Homopolymer of monomer 1 in Table 1 above 0.06 g
(Homopolymer in the present invention, weight average molecular weight: 8000)

[Example 7]
In Example 6, the same procedure as in Example 6 was used except that 0.06 g of the homopolymer of monomer 4 in Table 1 (weight average molecular weight: 24000) was used instead of the homopolymer of monomer 1 in Table 1 above. A magenta ink (7) of the present invention was obtained.

[Example 8]
In Example 6, the same procedure as in Example 6 was used, except that 0.06 g of the homopolymer of monomer 5 in Table 1 (weight average molecular weight: 10,000) was used instead of the homopolymer of monomer 1 in Table 1 above. A magenta ink (8) of the present invention was obtained.

[Example 9]
In Example 6, the same procedure as in Example 6 was used except that 0.06 g of the homopolymer of monomer 9 in Table 1 (weight average molecular weight: 15000) was used instead of the homopolymer of monomer 1 in Table 1 above. A magenta ink (9) of the present invention was obtained.

[Comparative Example 4]
In Example 6, a comparative magenta ink (4) was used in the same manner as in Example 6 except that 0.06 g of “Zonyl FSN100 (manufactured by Du Pont)” was used instead of the homopolymer of monomer 1 in Table 1. ') Got.

[Comparative Example 5]
In Example 6, a comparative magenta ink (5 ′) was obtained in the same manner as in Example 6 except that the homopolymer of monomer 1 in Table 1 was not used.

《Image recording and evaluation》
The present invention and the comparative magenta ink and yellow ink (1) to (5 ′) obtained from the above were sequentially loaded into an ink jet printer (print density 300 dpi, droplet ejection frequency 1 to 4 kHz, nozzle number 64), Each ink is ejected onto a PET film (thickness 50 μm) to record a color image. After recording, an exposure energy of 400 mJ / cm ² is obtained using a Deep UV lamp “SP-7” (USHIO). Irradiation was performed under the conditions, and a color image sample having a reflection density of about 1.0 was produced.
Subsequently, the following evaluation was performed on each of the obtained color images. The evaluation results are shown in Table 2 below.

1. Surface tension The surface tension of each ink was measured using an automatic surface tension meter “CBVP-A3” (manufactured by Kyowa Interface Science Co., Ltd.).

2. Dischargeability The ink dischargeability was observed with a high-speed camera and evaluated according to the following criteria.
[Standard]
○: No satellites (fine particles) and good.
Δ: Satellite generation was slightly observed.
X: Satellite was generated frequently and was defective.

3. Image quality The image forming surface was visually observed and evaluated according to the following criteria.
[Standard]
A: An image having a smooth surface and a uniform density was formed.
Δ: The ink was slightly repelled and the image was slightly non-uniform in density.
X: The image was non-uniform in density with many portions where ink was repelled.

4). Heat resistance Each ink was stored in an oven at 60 ° C. for 4 weeks, and the viscosity (mPa · s) at 25 ° C. before and after storage was measured using a RE80L viscometer (manufactured by Toki Sangyo Co., Ltd.).
The smaller the difference in viscosity before and after storage, the better the heat resistance.

5. Wettability The wettability of each ink with respect to PET was evaluated as follows.
Each ink was coated on a PET film with a wire bar, a coating layer having a thickness of 10 μm was provided, and the surface state of the coating was visually observed according to the following criteria.
[Standard]
○: The ink was uniformly applied to the entire surface.
Δ: The ink was slightly repelled, and the presence of an uncoated part was slightly recognized.
X: The ink was repelled considerably, and the coating layer was not uniform as a whole.

As shown in Table 2, the magenta ink and the yellow inks (1) to (9) of the present invention using the polymer of the present invention as a surfactant are excellent in ejection property and image quality, and have heat resistance during storage. It can be seen that the wettability to PET is high without loss. Moreover, it turns out that the polymer in this invention can fully exhibit an effect, even if it is a little addition (about 0.30 mass% with respect to a polymeric compound).
On the other hand, the comparative magenta ink and yellow ink (1 ′) (2 ′) and (4 ′) which did not use the polymer of the present invention as the surfactant were all inferior in heat resistance during storage. It was. The comparative magenta ink and yellow ink (3 ′) and (5 ′), which did not use a surfactant, were excellent in heat resistance but poor in wettability to PET.

In addition, “Zonyl FSN100 (manufactured by Du Pont)” used for the comparison has the following structure.
_{Rf-CH 2 CH 2 O (} CH 2 CH 2 0) x H
Wherein indicates the _{Rf = F (CF 2 CF 2} ) y. Moreover, x is about 0-25 and y is about 1-9. ]

Claims (11)

An ink composition comprising a polymerizable compound, a photopolymerization initiator, and a homopolymer of a monomer represented by the following general formula (1).

[In general formula (1), n represents the integer of 2-14. R represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. L represents a single bond or a divalent organic group containing at least one atom selected from an oxygen atom, a nitrogen atom, a sulfur atom and a carbon atom. ]   The ink composition according to claim 1, wherein the homopolymer has a weight average molecular weight (MW) of 3000 or more.   The ink composition according to claim 1, wherein the polymerizable compound contains at least one oxetane group-containing compound and at least one oxirane group-containing compound.   The polymerizable compound includes at least one trifunctional or higher functional (meth) acrylate and at least one selected from monofunctional (meth) acrylate and bifunctional (meth) acrylate. Item 4. The ink composition according to any one of Items 1 to 3.   The ink composition according to claim 1, further comprising a colorant.   The ink composition according to claim 5, wherein the colorant is a pigment or an oil-soluble dye.   The ink composition according to claim 6, wherein the oil-soluble dye has an oxidation potential nobler than 1.0 V (vs SCE).   The ink composition according to claim 1, wherein the ink composition is used for ink jet recording. An image recording step of recording an image on a recording material using the ink composition according to claim 1;
An image curing step of irradiating and curing an active energy ray on the image recorded on the recording material in the image recording step;
An image forming method comprising:   The image forming method according to claim 9, wherein the image recording step records the image by inkjet recording in which the ink composition is discharged.   A recorded matter comprising the ink composition according to any one of claims 1 to 8.