JP2007084594A - Ink composition, inkjet-recording method, printed matter, method for producing lithographic printing plate and lithographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an ink composition, curing in high sensitivity by the irradiation of an active radiation, capable of forming a high picture quality image, excellent in close adhesion onto a medium to be recorded and also having good preservation stability, a method of inkjet-recording by using the ink composition, also a printed matter obtained by using the ink composition excellent in preservation stability, and capable of being cured by the irradiation of ultraviolet light in high sensitivity, a lithographic printing plate and a method for producing the lithographic printing plate. <P>SOLUTION: This ink composition characterized by containing (a) a cationic polymerization initiator expressed by formula (I) or formula (II) and (b) a cationically polymerizable compound, the inkjet-recording method by using the ink composition, the printed matter obtained by the ink composition, the lithographic printing plate and the method for producing the lithographic printing plate are provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

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

  Patent Document 1 discloses an actinic ray curable composition and an actinic ray curable composition that are excellent in character quality, have no color mixing, and can record high-definition images very stably even under various printing environments. For the purpose of providing a type ink, it has been proposed to use an oxetane compound and a sensitizer in combination.

JP 2004-091556 A

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

The above object was achieved by the following <1>, <6>, and <8> to <10>. It is shown below with <2>-<5> and <7> which are preferable embodiments.
<1> (a) a cationic polymerization initiator represented by the following formula (I), and (b) a cationically polymerizable compound,

（式（I）又は式（II）中、Ａｒは縮合多環芳香環から水素原子を（ｎ＋１）個除いた基を表し、Ｌは単結合又は二価の連結基を表し、Ｒ¹〜Ｒ⁴はそれぞれ独立に、一価の有機基を表し、Ｘ^-は有機酸又は無機酸の共役塩基を表し、Ｒ¹の置換数ｎは０以上の整数を表し、Ｒ²の置換数ｍは０〜４の整数を表し、Ｒ³の置換数ｐは０〜５の整数を表し、また、Ｒ⁴の置換数ｑは０〜５の整数を表す。ただし、Ｌの一端はベンゼン環上の任意の位置若しくは硫黄原子に直接結合しているものとし、また、Ｒ²〜Ｒ⁴はベンゼン環上の任意の位置で結合しているものとする。）、
＜２＞ インク組成物が（ｄ）着色剤を含有する上記＜１＞に記載のインク組成物、
＜３＞ （ｄ）着色剤が顔料又は油溶性染料である上記＜２＞に記載のインク組成物、
＜４＞ 油溶性染料の酸化電位が１．０Ｖ（ｖｓＳＣＥ）以上である上記＜３＞に記載のインク組成物、
＜５＞ インクジェット記録用である上記＜１＞〜＜４＞いずれか１つに記載のインク組成物、
＜６＞ （ａ）被記録媒体上にインク組成物を吐出する工程、及び（ｂ）吐出されたインク組成物に活性放射線を照射してインク組成物を硬化する工程、を含むインクジェット記録方法であって、前記インク組成物が上記＜１＞〜＜５＞いずれか１つに記載のインク組成物であるインクジェット記録方法、
＜７＞ 前記活性放射線が、発光ピーク波長が３５０〜４２０ｎｍの範囲にあり、かつ被記録媒体表面での最高照度が１０〜２，０００ｍＷ／ｃｍ²となる紫外線を発生する発光ダイオードにより照射される紫外線である上記＜６＞に記載のインクジェット記録方法、
＜８＞ 上記＜６＞又は＜７＞に記載のインクジェット記録方法によって記録された印刷物、
＜９＞ （ａ）上記＜１＞〜＜５＞いずれか１つに記載のインク組成物を親水性支持体上に吐出する工程、及び（ｂ）吐出されたインク組成物に活性放射線を照射して、前記インク組成物を硬化させることにより、前記インク組成物が硬化してなる疎水性画像を前記親水性支持体上に形成する工程、を含む平版印刷版の製造方法、
＜１０＞ 上記＜９＞に記載の平版印刷版の製造方法によって製造された平版印刷版。

(In formula (I) or formula (II), Ar represents a group obtained by removing (n + 1) hydrogen atoms from a condensed polycyclic aromatic ring, L represents a single bond or a divalent linking group, and R ^{1 to} R ⁴ each independently represents a monovalent organic group, X ⁻ represents a conjugate base of an organic acid or an inorganic acid, the substitution number n of R ¹ represents an integer of 0 or more, and the substitution number m of R ² is 0. Represents an integer of -4, the substitution number p of R ³ represents an integer of 0 to 5, and the substitution number q of R ⁴ represents an integer of 0 to 5. However, one end of L is an arbitrary number on the benzene ring Or R ^{2 to} R ⁴ are bonded at any position on the benzene ring).
<2> The ink composition according to <1>, wherein the ink composition contains (d) a colorant;
<3> (d) The ink composition according to <2>, wherein the colorant is a pigment or an oil-soluble dye.
<4> The ink composition according to <3>, wherein the oxidation potential of the oil-soluble dye is 1.0 V (vs SCE) or more.
<5> The ink composition according to any one of the above <1> to <4>, which is for inkjet recording.
<6> An inkjet recording method comprising: (a) a step of discharging an ink composition onto a recording medium; and (b) a step of irradiating the discharged ink composition with actinic radiation to cure the ink composition. An ink jet recording method, wherein the ink composition is the ink composition according to any one of the above items <1> to <5>.
<7> The actinic radiation is irradiated by a light emitting diode that generates ultraviolet rays having an emission peak wavelength in a range of 350 to 420 nm and a maximum illuminance on a recording medium surface of 10 to 2,000 mW / cm ² The inkjet recording method according to <6>, wherein the inkjet recording method is ultraviolet light;
<8> Printed matter recorded by the inkjet recording method according to <6> or <7> above,
<9> (a) A step of discharging the ink composition according to any one of the above <1> to <5> onto a hydrophilic support, and (b) irradiating the discharged ink composition with actinic radiation. A method of producing a lithographic printing plate, comprising: a step of curing the ink composition to form a hydrophobic image formed by curing the ink composition on the hydrophilic support;
<10> A lithographic printing plate produced by the method for producing a lithographic printing plate as described in <9> above.

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

  The ink composition of the present invention (hereinafter also simply referred to as “ink”) contains (a) a cationic polymerization initiator represented by the following formula (I), and (b) a cationic polymerizable compound. Features.

（式（I）又は式（II）中、Ａｒは縮合多環芳香環から水素原子を（ｎ＋１）個除いた基を表し、Ｌは単結合又は二価の連結基を表し、Ｒ¹〜Ｒ⁴はそれぞれ独立に、一価の有機基を表し、Ｘ^-は有機酸又は無機酸の共役塩基を表し、Ｒ¹の置換数ｎは０以上の整数を表し、Ｒ²の置換数ｍは０〜４の整数を表し、Ｒ³の置換数ｐは０〜５の整数を表し、また、Ｒ⁴の置換数ｑは０〜５の整数を表す。ただし、Ｌの一端はベンゼン環上の任意の位置若しくは硫黄原子に直接結合しているものとし、また、Ｒ²〜Ｒ⁴はベンゼン環上の任意の位置で結合しているものとする。）
以下、本発明について詳細に説明する。

(In formula (I) or formula (II), Ar represents a group obtained by removing (n + 1) hydrogen atoms from a condensed polycyclic aromatic ring, L represents a single bond or a divalent linking group, and R ^{1 to} R ⁴ independently represents a monovalent organic group, X ⁻ represents a conjugate base of an organic acid or an inorganic acid, the substitution number n of R ¹ represents an integer of 0 or more, and the substitution number m of R ² is 0. The number of substitution p of R ³ represents an integer of 0 to 5, and the number of substitution q of R ⁴ represents an integer of 0 to 5. However, one end of L is an arbitrary number on the benzene ring. And R ^{2 to} R ⁴ are bonded at any position on the benzene ring.)
Hereinafter, the present invention will be described in detail.

(1) Components contained in ink composition The ink composition of the present invention is curable by radiation, and (a) a cationic polymerization initiator represented by the formula (I) (hereinafter referred to as “specific cationic polymerization initiator”). And (b) containing a cationically polymerizable compound, and if necessary, (c) a colorant, (d) a sensitizing dye, (e) a co-sensitizer, and (f) other polymerizable compounds. It may contain a compound, (g) other polymerization initiator, and (h) other components.
The “radiation” referred to in the present invention is not particularly limited as long as it is an actinic radiation that can impart energy capable of generating an initial species in the ink composition by irradiation, and is broadly α-ray, γ-ray, X Among these, ultraviolet rays and electron beams are preferable, and ultraviolet rays and electron beams are particularly preferable from the viewpoints of curing sensitivity and device availability. Therefore, the ink composition of the present invention is preferably an ink composition that can be cured by irradiating ultraviolet rays as radiation.

(A) Cationic polymerization initiator represented by formula (I) or formula (II) The cationic polymerization initiator used in the present invention is a cationic polymerization initiator represented by formula (I) or formula (II) (" Also referred to as “compound represented by formula (I) or formula (II)”. In the present invention, the cationic polymerization initiator represented by the formula (I) or the formula (II) may be used alone or in combination of two or more.
In the formula (I) or (II), Ar represents a group obtained by removing (n + 1) hydrogen atoms from a condensed polycyclic aromatic ring. N is the number of substitutions of R ¹ on the condensed polycyclic aromatic ring.
Examples of the condensed polycyclic aromatic ring include anthracene, phenanthrene, naphthalene, indacene, acenaphthylene, fluoranthene, acehenanthrylene, aceanthrylene, tetracene, triphenylene, pyrene, and chrysene. Among these, anthracene, Or it is preferable that it is phenanthrene. Ar in formula (I) or formula (II) is a group obtained by removing the number of hydrogen atoms obtained by adding the number of substitutions n of R ^{1 and} the number of substitutions ¹ of L ¹ from the condensed polycyclic aromatic ring.

In the formula (I) or formula (II), L represents a single bond or a divalent linking group, one end of L is bonded at an arbitrary position on the condensed polycyclic aromatic ring, and the other end of L Are bonded at any position on the benzene ring.
The divalent linking group represented by L is preferably a divalent linking group comprising an atom or an atomic group containing at least one of a carbon atom, a nitrogen atom, a sulfur atom, and an oxygen atom. Preferably, an alkylene group (eg methylene, ethylene, propylene, butylene, pentylene), an arylene group (eg phenylene, naphthylene), an alkynylene group (eg ethenylene, propenylene), an alkynylene group (eg nitinylene, propynylene), carbonyl Oxyalkylene group (for example, carbonyloxyethylene, carbonyloxypropylene), carbonyloxy group, amide group, ester group, sulfoamide group, sulfonate group, ureido group, sulfonyl group, sulfinyl group, thioether group, ether group, carbonyl group , -N (Ra)-(Ra represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group), a divalent heterocyclic group (for example, 6-chloro-1,3, 5-triazine-2, -Diyl group, pyrimidine-2,4-diyl group, quinoxaline-2,3-diyl group), or a divalent linking group having 1 to 20 carbon atoms constituted by combining two or more. . These divalent linking groups may be further substituted, and examples of the substituent include groups selected from the substituent group described below.
The compound represented by the formula (II) includes a compound represented by the formula (I) in a broad sense. In the present invention, the compound represented by the formula (II) is a sulfur atom. A compound having a benzene ring directly bonded to is assumed to be included in the compound represented by the formula (I).

As the divalent linking group or single bond represented by L, more preferably, an alkylene group having 1 to 20 carbon atoms (for example, methylene, ethylene, propylene, butylene), an arylene group having 6 to 20 carbon atoms (for example, Phenylene, naphthylene), alkynylene groups having 2 to 20 carbon atoms (for example, ethenylene, propenylene), carbonyloxyalkylene groups having 3 to 7 carbon atoms (for example, carbonyloxyethylene, carbonyloxypropylene), carbonyl having 3 to 7 carbon atoms Examples thereof include an oxyalkyleneoxy group (for example, carbonyloxyethyleneoxy, carbonyloxypropyleneoxy), a divalent linking group having 1 to 20 carbon atoms configured by combining one or more carbonyloxy groups, or a single bond. It is done.
Among these, carbonyloxyalkylene groups having 3 to 7 carbon atoms (for example, carbonyloxyethylene, carbonyloxypropylene), carbonyloxyalkyleneoxy groups having 3 or 4 carbon atoms (for example, carbonyloxyethyleneoxy, carbonyloxypropyleneoxy) A carbonyloxy group is preferred.

In Formula (I) or Formula (II), R ^{1 to} R ⁴ each independently represents a monovalent organic group, R ¹ is bonded at an arbitrary position on the condensed polycyclic aromatic ring, and R ^{1 2 to} R ⁴ are bonded at an arbitrary position on each benzene ring.
Examples of the monovalent organic group in R ^{1 to} R ⁴ include a halogen atom (fluorine, bromine, chlorine, iodine), a hydroxyl group, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, and 2 carbon atoms. -20 alkynyl group, aryl group having 6-20 carbon atoms, arylalkyl group having 7-21 carbon atoms, alkoxy group having 1-20 carbon atoms, aryloxy group having 6-20 carbon atoms, acyl having 2-20 carbon atoms Group, an alkoxycarbonyl group having 2 to 20 carbon atoms, an acyloxy group having 1 to 20 carbon atoms, a hydrocarbon ring group having 3 to 20 carbon atoms, a heterocyclic group having 4 to 20 carbon atoms, and a silyl group having 3 to 30 carbon atoms , or represents -SO ₃ -R ^0, R ⁰ is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, an alkynyl group having 2 to 20 carbon atoms, 6 to 20 carbon atoms Aryl group having 7 to 21 carbon atoms Arylalkyl group, an alkali metal atom or quaternary ammonium.

The alkyl group for R ^{1 to} R ⁴ preferably has 1 to 18 carbon atoms, particularly preferably 1 to 12 carbon atoms, and may be linear or have a substituent.
The alkenyl group for R ^{1 to} R ⁴ preferably has 2 to 18 carbon atoms, particularly preferably 2 to 12 carbon atoms, and may further have a substituent.
The alkynyl group of R ^{1 to} R ⁴ preferably has 2 to 18 carbon atoms, particularly preferably 2 to 12 carbon atoms, and may further have a substituent.
The aryl group for R ^{1 to} R ⁴ preferably has 6 to 14 carbon atoms, particularly preferably 6 to 10 carbon atoms, and may further have a substituent.
The arylalkyl group for R preferably has 7 to 15 carbon atoms, particularly preferably 7 to 11 carbon atoms, and may further have a substituent.
The alkoxy group of R ^{1 to} R ⁴ preferably has 1 to 18 carbon atoms, particularly preferably 1 to 12 carbon atoms, and may be linear or have a substituent. Moreover, as an alkyl part of an alkoxy group, the heterocyclic group except the alkenyl group, alkynyl group, arylalkyl group, hydrocarbon ring group, or aromatic other than the said alkyl group is mentioned.
The aryloxy group for R ^{1 to} R ⁴ preferably has 6 to 14 carbon atoms, particularly preferably 6 to 10 carbon atoms, and may further have a substituent. Moreover, as an aryl part of an aryloxy group, a hetero aromatic ring group other than the said aryl group is mentioned.
As the acyl group or alkoxycarbonyl group of R ^{1 to} R ^4, the number of carbon atoms on the carbon chain side is particularly preferably 1 to 12, each of which may be linear or have a substituent. Good.
The acyloxy group for R ^{1 to} R ⁴ preferably has 1 to 18 carbon atoms, particularly preferably 1 to 12 carbon atoms, and may be linear or have a substituent.
The hydrocarbon ring group of R ^{1 to} R ^{4 is} a hydrocarbon ring group other than the aryl group, and a substituted or unsubstituted hydrocarbon ring group having 3 to 14 carbon atoms is preferable.
The heterocyclic group of R ^{1 to} R ⁴ is preferably a substituted or unsubstituted heterocyclic group having 3 to 13 carbon atoms, and the hetero atom contained in the heterocyclic group includes a nitrogen atom, an oxygen atom or a sulfur atom. It is preferable that
The R ⁰ in -SO ₃ -R ⁰ of R ¹ to R ^4, a hydrogen atom, the alkyl group, the aryl group, the arylalkyl group, the lithium atom is preferably a sodium atom or a potassium atom.

In formula (I) or formula (II), the substitution number n of R ¹ represents an integer of 0 to k. Note that k is an integer of 1 or more.
When n is 0, it means that there is no R ¹ on the condensed polycyclic aromatic ring of the compound represented by formula (I) or formula (II), and when n is 1 to k, condensed polycyclic aromatic It represents that ¹ to k R ^{1 s} are present on the ring.
When n is 2 or more, a monovalent organic group can be selected independently for each R ¹ on the condensed polycyclic aromatic ring, and two or more R ¹ can be bonded to each other to form a ring. You may do it.
The substitution number m of R ² in formula (I) represents an integer of 0 to 4.
When m is 0, it means that there is no R ² on the benzene ring of the compound represented by formula (I), and when m is 1 to 4, 1 to 4 R ² are present on the benzene ring. Represents something.
When m is 2 or more, monovalent organic groups can be selected independently of each other for R ² on the benzene ring, and two or more R ² are bonded to each other to form a ring. Also good.
The substitution number p of R ^{3 in} the formula (I) or the formula (II) represents an integer of 0 to 5.
When p is 0, it represents that there is no R ³ on the benzene ring of the compound represented by formula (I) or formula (II), and when p is 1 to 5, R ³ is present on the benzene ring. It represents 1 to 5 each.
When p is 2 or more, monovalent organic groups can be selected independently of each other for R ³ on the benzene ring, and two or more R ³ are bonded to each other to form a ring. Also good.
The substitution number q of R ^{4 in} the formula (I) or the formula (II) represents an integer of 0 to 5.
When q is 0, it means that there is no R ⁴ on the benzene ring of the compound represented by formula (I) or formula (II), and when q is 1 to 5, R ⁴ is on the benzene ring. It represents 1 to 5 each.
Further, when q is 2 or more, monovalent organic groups can be selected independently of each other for each R ⁴ on the benzene ring, and two or more R ⁴ are bonded to each other to form a ring. Also good.

L divalent linking group, R ^{1 to} R ⁴ alkyl group, alkenyl group, alkynyl group, aryl group, arylalkyl group, acyl group, alkoxycarbonyl group, hydrocarbon ring group, heterocyclic group, or R ⁰ Examples of the substituent that the group exemplified above may have include the following substituent group.
(Substituent group)
And the aforementioned halogen atom, alkyl group, alkenyl group, alkynyl group, aryl group, arylalkyl group, acyl group, alkoxycarbonyl group, hydrocarbon ring group, heterocyclic group, and —SO ₃ —R ₀ , and Hydroxy group, alkoxy group, aryloxy group, N, N-dialkylamino group, N, N-diarylamino group, N-alkyl-N-arylamino group, alkylsulfoxy group, arylsulfoxy group, N-alkylacylamino Group, N-arylacylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, N-alkyl-N-alkoxycarbonylamino group, N-alkyl-N-aryloxycarbonylamino group, N-aryl-N-alkoxy A carbonylamino group, an N, N-dialkylcarbamoyl group, -Arylcarbamoyl group, N, N-diarylcarbamoyl group, N-alkyl-N-arylcarbamoyl group, alkylsulfinyl group, arylsulfinyl group, alkylsulfonyl group, arylsulfonyl group, N, N-dialkylsulfinamoyl group, N , N-diarylsulfinamoyl group, N-alkyl-N-arylsulfinamoyl group, N, N-dialkylsulfamoyl group, N, N-diarylsulfamoyl group, N-alkyl-N-arylsulfa Moyl group, dialkylphosphono group (—PO ₃ (alkyl) ₂ ), diarylphosphono group (—PO ₃ (aryl) ₂ ), alkylarylphosphono group (—PO ₃ (alkyl) (aryl)), dialkylphospho Nooxy group (—OPO ₃ (alkyl) ₂ ), diarylphosphonooxy group (—OPO ₃ (aryl) ₂ ), an alkylarylphosphonooxy group (—OPO ₃ (alkyl) (aryl)), a cyano group, a nitro group, an alkenyl group, and an alkynyl group. Further, these substituents may be further substituted with these substituents, and if possible, may be bonded to each other to form a ring.

Further, the compound represented by the formula (I) or the formula (II) is preferably a compound having at least one R ¹ having a silyl group or a group containing a silyl group. When there is a silyl group or a group containing a silyl group on the condensed polycyclic aromatic ring, the reverse electron transfer from the cationic polymerization active species to the specific sensitizing dye is suppressed, and the electron transfer efficiency is improved, and the ink composition The curing reaction can be made highly sensitive.
The compound represented by the formula (I) or the formula (II) preferably has one or more halogen atoms as a monovalent organic group in R ^{1 to} R ⁴ for ease of electron transfer.

In Formula (I) or Formula (II), X ⁻ is not particularly limited as long as it is a conjugate base of an organic acid or an inorganic acid, and may be a high molecular compound or a low molecular compound, and may be a polyvalent anion. Good. These anions include R ^a1 —SO ₃ ⁻ , R ^a1 —SO ₂ ⁻ , R ^a1 —CO ₂ ⁻ , R ^a1 —CS ₂ ⁻ , R ^a1 —O—CS ₂ ⁻ , R ^a1 —S—CS _{2. ^{-, R a1 -O-PO 2}} -, (R a1 -O) 2 PO 2 -, R a1 (R a1 -O) PO 2 -, R a1 -EW 1 -A - -EW 2 -R a1, ( R ^a1 ) ₄ B ⁻ , an anion corresponding to an organic acid conjugate base such as Ar ^x O ⁻ , or F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , PF ₆ ⁻ , BF ₄ ⁻ , SbF ₆ ⁻ , ClO ₄ Corresponds to inorganic acid conjugate bases such as ⁻ , SO ₄ ²⁻ , NO ₃ ⁻ , CO ₃ ²⁻ , SCN ⁻ , CN ⁻ , SiF ₆ ⁻ , FSO ₃ ⁻ , I ₃ ⁻ , Br ₃ ⁻ , IBr ₂ ⁻ Anions can be mentioned.
Here, R ^a1 is an organic substituent, and represents an alkyl group, an alkenyl group, an alkynyl group, an aryl group, an aralkyl group, or a group further substituted with them. Or may be bonded to each other to form a ring.
EW ¹ and EW ² represent an electron-withdrawing group, and specific examples thereof include —SO—, —CO—, —SO ₂ —, and —CN.
A ⁻ represents —CR ^z1 —, —N ⁻ — (R ^z1 represents a hydrogen atom or a substituent).
Ar ^x represents an aryl group.
X ⁻ may be PF ₆ ⁻ , BF ₄ ⁻ , tetraalkylborate or tetraarylborate (for example, tetrakispentafluorophenylborate, tetrakis (3,5-trifluoromethylphenyl) from the viewpoint of reactivity and stability. ) Borate).

  Preferred examples of the cationic polymerization initiator represented by formula (I) or formula (II) that can be used in the present invention include compounds represented by the following formulas (III) to (VI). The compounds represented by the following formulas (III) to (VI) are preferably used alone or in combination of two or more.

（式（III）〜（VI）中、Ｌは単結合又は二価の連結基を表し、Ｒ¹〜Ｒ⁴はそれぞれ独立に、一価の有機基を表し、Ｘ^-は有機酸又は無機酸の共役塩基を表し、Ｒ¹の置換数ｎは０〜９の整数を表し、Ｒ²の置換数ｍは０〜４の整数を表し、Ｒ³の置換数ｐは０〜５の整数を表し、また、Ｒ⁴の置換数ｑは０〜５の整数を表す。ただし、Ｌの一端及びＲ¹はアントラセン環又はフェナントレン環上の任意の位置で結合しているものとし、Ｌの他端はベンゼン環上の任意の位置若しくは硫黄原子に直接結合しているものとし、また、Ｒ²〜Ｒ⁴はベンゼン環上の任意の位置で結合しているものとする。）

(In formulas (III) to (VI), L represents a single bond or a divalent linking group, R ^{1 to} R ⁴ each independently represents a monovalent organic group, and X ⁻ represents an organic acid or an inorganic acid. R ¹ substitution number n represents an integer of 0 to 9, R ² substitution number m represents an integer of 0 to 4, and R ³ substitution number p represents an integer of 0 to 5. In addition, the substitution number q of R ⁴ represents an integer of 0 to 5. However, one end of L and R ¹ are bonded at an arbitrary position on the anthracene ring or phenanthrene ring, and the other end of L is (It shall be directly bonded to any position or sulfur atom on the benzene ring, and R ^{2 to} R ⁴ shall be bonded to any position on the benzene ring.)

In formulas (III) to (VI), L has the same meaning as L in formula (I) or formula (II), and may have the above-described substituents, and the preferred range is also the same. . Further, one end of L is bonded at an arbitrary position (positions 1 to 10) on the anthracene ring or phenanthrene ring, and the other end of L is bonded at an arbitrary position on the benzene ring.
In the formulas (III) to (VI), L has the same meaning as R ^{1 to} R ⁴ in the formula (I) or the formula (II), respectively, and may have the above-mentioned substituents. The ranges are the same.
In the formulas (III) to (VI), X ⁻ has the same meaning as X ⁻ in the formula (I) or the formula (II), and may have the above-mentioned substituent, and the preferred range is also the same. It is.
In formulas (III) to (VI), one end of L and R ¹ are bonded at any position (1 to 10 positions) on the anthracene ring or phenanthrene ring, and the other end of L and R ^{2 to} R ⁴ is bonded at any position on the benzene ring.

The substitution number n of R ¹ in formulas (III) to (VI) represents an integer of 0 to 9.
When n is 0, it means that there is no R ¹ on the condensed polycyclic aromatic ring of the compounds represented by formulas (III) to (VI), and when n is 1 to 9, the condensed polycyclic aromatic ring It represents that there are 1 to 9 R ¹ each.
When n is 2 or more, a monovalent organic group can be selected independently for each R ¹ on the condensed polycyclic aromatic ring, and two or more R ¹ can be bonded to each other to form a ring. You may do it.
The substitution number m of R ^{2 in} the formula (III) or (IV) represents an integer of 0 to 4.
When m is 0, it means that there is no R ² on the benzene ring of the compound represented by formula (III) or (IV), and when m is 1 to 4, R ² is on the benzene ring. 1 to 4 are represented.
When m is 2 or more, monovalent organic groups can be selected independently of each other for R ² on the benzene ring, and two or more R ² are bonded to each other to form a ring. Also good.
The substitution number p of R ³ in formulas (III) to (VI) represents an integer of 0 to 5.
When p is 0, it means that there is no R ³ on the benzene ring of the compounds represented by formulas (III) to (VI), and when p is 1 to 5, R ³ is on the benzene ring. 1 to 5 are represented.
When p is 2 or more, monovalent organic groups can be selected independently of each other for R ³ on the benzene ring, and two or more R ³ are bonded to each other to form a ring. Also good.
The substitution number q of R ⁴ in formulas (III) to (VI) represents an integer of 0 to 5.
When q is 0, it means that there is no R ⁴ on the benzene ring of the compounds represented by formulas (III) to (VI), and when q is 1 to 5, R ⁴ is on the benzene ring. 1 to 5 are represented.
Further, when q is 2 or more, monovalent organic groups can be selected independently of each other for each R ⁴ on the benzene ring, and two or more R ⁴ are bonded to each other to form a ring. Also good.
The monovalent organic group in R ^{1 to} R ⁴ preferably has a halogen atom for easy electron transfer.

  Preferred examples of the cationic polymerization initiator represented by the formula (I) or the formula (II) that can be used in the present invention include compounds represented by the following formula (III) or (VII). The compounds represented by the following formula (III) or (VII) are preferably used alone or in combination of two or more.

Wherein ^{(VII), R 1, R} 3, R 4, L, X, n, p, q are, R ^1, R ³ in the formula ^{(V), R 4, L} , X, n, p, It is synonymous with q, and its preferable range is also the same.
The monovalent organic group in R ^{1 to} R ⁴ in the formula (VII) preferably has a halogen atom for ease of electron transfer.
As the cationic polymerization initiator represented by formula (I) or formula (II) that can be used in the present invention, the compound represented by formula (III) can be most preferably mentioned.

The ink composition of the present invention comprises a cationic polymerization initiator represented by formula (I) or formula (II), which is a molecule in which a condensed polycyclic aromatic ring skeleton and a sulfonium salt structure are linked (hereinafter referred to as “specific cationic polymerization initiation”). In other words, the absorption efficiency of the irradiated active radiation is improved and the curing sensitivity is improved. In addition, the condensed polycyclic aromatic ring skeleton in the specific cationic polymerization initiator excited by absorbing active radiation, particularly ultraviolet rays, efficiently performs electron transfer or energy transfer to the sulfonium salt structure, Therefore, the curing reaction of the ink composition can be made highly sensitive.
In addition, the polymerization initiator having a triarylsulfonium salt structure generally has a high stability of the compound and tends to have a low generation efficiency of the cationic polymerization initiating species, but the cation represented by the formula (I) used in the present invention Since the polymerization initiator has a condensed polycyclic aromatic ring skeleton and a sulfonium salt structure in the same molecule, an active cationic polymerization initiating species can be generated efficiently, and the curing reaction of the ink composition can be highly sensitive. Can do.
Furthermore, a structure having a condensed polycyclic aromatic ring skeleton and a sulfonium salt in the same molecule has little influence on the colorant due to its light absorption characteristics, and is excellent in color reproducibility of yellow, magenta and cyan inks.

  The method for synthesizing the cationic polymerization initiator represented by the formula (I) or the formula (II) is not particularly limited. For example, J. Polymer Sci: Part A: Polymer Chemistry, 34, 3231-3253 (1996) , J. Polymer Sci: Part A: Polymer Chemistry, 38, 1433-1442 (2000) and the like, and various formulas (I) or ( The cationic polymerization initiator represented by II) can be synthesized.

Among the compounds represented by the formula (I) or the formula (II), as preferred embodiments, the following compounds (I-1) to (I-25) and (II-1) to (II-10) Can be mentioned.
Abbreviations in the following compounds are as follows.
Me: CH ₃
Bu: CH ₂ CH ₂ CH ₂ CH ₃

Moreover, as a compound represented by the said formula (I) or formula (II) which can be used for this invention, the said compound (I-1)-(I-25) and (II-1)-(II-10) the BF ₄ ^{- -} PF ₆ is a counter anion) compound with or tetrakispentafluorophenylborate also preferably exemplified.

(B) Cationic polymerizable compound The ink composition of the present invention contains a cationic polymerizable compound.
The cationically polymerizable compound that can be used in the present invention is not particularly limited as long as it is a compound that starts and cures by a cationic polymerization initiating species generated from a cationic polymerization initiator described later, and is a photocationically polymerizable monomer. Various known cationically polymerizable monomers known as can be used. Examples of the cationic polymerizable monomer include JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-310937, and 2001-2001. Examples thereof include epoxy compounds, vinyl ether compounds, oxetane compounds and the like described in each publication such as No. 220526. In addition, as the cationic polymerizable compound, for example, a cationic polymerization-based photocurable resin is known, and recently, a photocationic polymerization-based photocurable resin sensitized to a visible light wavelength region of 400 nm or more, For example, they are disclosed in JP-A-6-43633 and JP-A-8-324137.

  Examples of the epoxy compound include aromatic epoxides, alicyclic epoxides, aromatic epoxides, etc. The aromatic epoxide includes, for example, a polyhydric phenol having at least one aromatic nucleus or an alkylene oxide adduct thereof and epichlorohydrin. Di- or polyglycidyl ethers produced by reaction, for example, di- or polyglycidyl ethers of bisphenol A or its alkylene oxide adducts, di- or polyglycidyl ethers of hydrogenated bisphenol A or its alkylene oxide adducts, and novolaks Type epoxy resin and the like. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

As the alicyclic epoxide, cyclohexene oxide obtained by epoxidizing a compound having at least one cycloalkane ring such as cyclohexene or cyclopentene ring with a suitable oxidizing agent such as hydrogen peroxide or peracid. Or a cyclopentene oxide containing compound is mentioned preferably.
Examples of the aliphatic epoxide include di- or polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. Typical examples thereof include diglycidyl ether of ethylene glycol, diglycidyl ether of propylene glycol, or 1 Of diglycidyl ether of alkylene glycol such as diglycidyl ether of 1,6-hexanediol, polyglycidyl ether of polyhydric alcohol such as di- or triglycidyl ether of glycerin or alkylene oxide adduct thereof, polyethylene glycol or alkylene oxide adduct thereof Dialkylidyl ether, polypropylene glycol, or polyalkylene glycol jig represented by diglycidyl ether of alkylene oxide adducts thereof Glycidyl ether and the like. Here, examples of the alkylene oxide include ethylene oxide and propylene oxide.

The monofunctional and polyfunctional epoxy compounds that can be used in the present invention are exemplified in detail.
Examples of the monofunctional epoxy compound include phenyl glycidyl ether, p-tert-butylphenyl glycidyl ether, butyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, 1,2-butylene oxide, 1,3-butadiene monooxide. 1,2-epoxydodecane, epichlorohydrin, 1,2-epoxydecane, styrene oxide, cyclohexene oxide, 3-methacryloyloxymethylcyclohexene oxide, 3-acryloyloxymethylcyclohexene oxide, 3-vinylcyclohexene oxide, etc. It is done.

  Examples of polyfunctional epoxy compounds include bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol S diglycidyl ether, brominated bisphenol A diglycidyl ether, brominated bisphenol F diglycidyl ether, brominated bisphenol S Glycidyl ether, epoxy novolac resin, hydrogenated bisphenol A diglycidyl ether, hydrogenated bisphenol F diglycidyl ether, hydrogenated bisphenol S diglycidyl ether, 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate, 2- (3,4-epoxycyclohexyl-5,5-spiro-3,4-epoxy) cyclohexane-meta-dioxane, bis (3,4-epoxycyclohexane Silmethyl) adipate, vinylcyclohexene oxide, 4-vinylepoxycyclohexane, bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate, 3,4-epoxy-6-methylcyclohexyl-3 ′, 4′-epoxy-6 '-Methylcyclohexanecarboxylate, methylenebis (3,4-epoxycyclohexane), dicyclopentadiene diepoxide, ethylene glycol di (3,4-epoxycyclohexylmethyl) ether, ethylenebis (3,4-epoxycyclohexanecarboxylate) , Epoxyhexahydrophthalate dioctyl, epoxyhexahydrophthalate di-2-ethylhexyl, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether Glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ethers, 1,1,3-tetradecadiene dioxide, limonene dioxide, 1,2,7,8 -Diepoxyoctane, 1,2,5,6-diepoxycyclooctane and the like.

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

  Examples of 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 trivinyl ether compounds such as methylolpropane trivinyl ether, ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, hydroxybutyl vinyl ether, 2-ethylhexyl vinyl ether, cyclohexane dimethanol monovinyl ether, n-propyl Pills vinyl ether, isopropyl vinyl ether, isopropenyl ether -O- propylene carbonate, dodecyl vinyl ether, diethylene glycol monovinyl ether, and octadecyl vinyl ether.

Below, monofunctional vinyl ether and polyfunctional vinyl ether are illustrated in detail.
Examples of the monofunctional vinyl ether include methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, n-butyl vinyl ether, t-butyl vinyl ether, 2-ethylhexyl vinyl ether, n-nonyl vinyl ether, lauryl vinyl ether, cyclohexyl vinyl ether, cyclohexyl methyl vinyl ether, 4-methyl Cyclohexylmethyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenoxyethyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether, ethoxyethoxyethyl vinyl ether, methoxypolyethylene glycol vinyl ether , Tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethylcyclohexyl methyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chloroethyl vinyl ether, chlorobutyl vinyl ether, chloroethoxy Examples include ethyl vinyl ether, phenyl ethyl vinyl ether, phenoxy polyethylene glycol vinyl ether, and the like.

Examples of the polyfunctional vinyl ether include ethylene glycol divinyl ether, diethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, butylene glycol divinyl ether, hexanediol divinyl ether, bisphenol A alkylene oxide divinyl ether, and bisphenol F alkylene oxide. Divinyl ethers such as divinyl ether; trimethylolethane trivinyl ether, trimethylolpropane trivinyl ether, ditrimethylolpropane tetravinyl ether, glycerin trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol pentavinyl ether, dipentaerythritol Savinyl ether, ethylene oxide-added trimethylolpropane trivinyl ether, propylene oxide-added trimethylolpropane trivinyl ether, ethylene oxide-added ditrimethylolpropane tetravinyl ether, propylene oxide-added ditrimethylolpropane tetravinyl ether, ethylene oxide-added pentaerythritol tetravinyl ether, propylene oxide addition Examples thereof include polyfunctional vinyl ethers such as pentaerythritol tetravinyl ether, ethylene oxide-added dipentaerythritol hexavinyl ether, and propylene oxide-added dipentaerythritol hexavinyl ether.
As the vinyl ether compound, a di- or trivinyl ether compound is preferable from the viewpoints of curability, adhesion to a recording medium, surface hardness of the formed image, and the like, and a divinyl ether compound is particularly preferable.

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

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

R ^a1 represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, a fluoroalkyl group having 1 to 6 carbon atoms, an allyl group, an aryl group, a furyl group, or a thienyl group. When two R ^a1 are present in the molecule, they may be the same or different.
Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group. Preferred examples of the fluoroalkyl group include those in which any hydrogen of these alkyl groups is substituted with a fluorine atom.
R ^a2 is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, a group having an aromatic ring, an alkylcarbonyl group having 2 to 6 carbon atoms, or 2 to 6 carbon atoms. Represents an alkoxycarbonyl group, and an N-alkylcarbamoyl group having 2 to 6 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, and a butyl group. Examples of the alkenyl group include a 1-propenyl group, a 2-propenyl group, a 2-methyl-1-propenyl group, and 2-methyl-2. -Propenyl group, 1-butenyl group, 2-butenyl group, 3-butenyl group and the like. Examples of the group having an aromatic ring include phenyl group, benzyl group, fluorobenzyl group, methoxybenzyl group, phenoxyethyl group and the like. Can be mentioned. As the alkylcarbonyl group, an ethylcarbonyl group, a propylcarbonyl group, a butylcarbonyl group, etc., as an alkoxycarbonyl group, an ethoxycarbonyl group, a propoxycarbonyl group, a butoxycarbonyl group, etc., as an N-alkylcarbamoyl group, Examples thereof include an ethylcarbamoyl group, a propylcarbamoyl group, a butylcarbamoyl group, and a pentylcarbamoyl group. R ^a2 may have a substituent, and examples of the substituent include an alkyl group of 1 to 6 and a fluorine atom.

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

When R ^a3 is the above polyvalent group, R ^a4 is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a halogen atom, a nitro group, a cyano group, a mercapto group, Represents a lower alkyl carboxyl group, a carboxyl group, or a carbamoyl group.
R ^a5 represents an oxygen atom, a sulfur atom, a methylene group, NH, SO, SO ₂ , C (CF ₃ ) ₂ , or C (CH ₃ ) ₂ .
R ^a6 represents an alkyl group having 1 to 4 carbon atoms or an aryl group, and n is an integer of 0 to 2,000. R ^a7 represents an alkyl group having 1 to 4 carbon atoms, an aryl group, or a monovalent group having the following structure. In the following formula, R ^a8 is an alkyl group having 1 to 4 carbon atoms or an aryl group, and m is an integer of 0 to 100.

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

  As a compound which has 3-4 oxetane rings, the compound shown by following formula (4) is mentioned, for example.

In the formula (4), R ^a1 has the same ^{meaning as} in the formula (1). Other examples of Ra ⁹ as a linking group include branched alkylene groups having 1 to 12 carbon atoms such as groups represented by the following A to C and branched poly ( An alkyleneoxy) group or a branched polysiloxy group such as a group represented by E below. j is 3 or 4.

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

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

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

The compound having such an oxetane ring is described in detail in JP-A No. 2003-341217, paragraph numbers 0021 to 0084, and the compound described herein can be suitably used in the present invention. Further, oxetane compounds described in JP-A-2004-91556 can also be used in the present invention. This is described in detail in paragraphs 0022 to 0058.
Among the oxetane compounds used in the present invention, it is preferable to use a compound having one oxetane ring from the viewpoint of the viscosity and tackiness of the ink composition.

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

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

(C-1) Pigment The pigment that can be used in the present invention is not particularly limited. For example, organic or inorganic pigments having the following numbers described in the color index can be used.

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

(C-2) Oil-soluble dye The oil-soluble dye that can be used in the present invention is described below.
The oil-soluble dye that can be used in the present invention means a dye that is substantially insoluble in water. Specifically, the solubility in water at 25 ° C. (the mass of the dye that can be dissolved in 100 g of water) is 1 g or less, preferably 0.5 g or less, more preferably 0.1 g or less. Accordingly, the oil-soluble dye means a so-called water-insoluble pigment or oil-soluble dye, and among these, an oil-soluble dye is preferable.

  In the present invention, the oil-soluble dye may be used alone or in combination of several kinds. In addition, other water-soluble dyes, disperse dyes, pigments, and other colorants may be contained as necessary as long as the effects of the present invention are not impaired.

  Among the oil-soluble dyes that can be used in the present invention, any yellow dye can be used. For example, phenols, naphthols, anilines, pyrazolones, pyridones, aryl or heteryl azo dyes having open-chain active methylene compounds as coupling components; for example, azomethine dyes having open-chain active methylene compounds as coupling components; Examples include methine dyes such as benzylidene dyes and monomethine oxonol dyes; quinone dyes such as naphthoquinone dyes and anthraquinone dyes; and other dye species such as quinophthalone dyes, nitro / nitroso dyes, and acridines. And dyes and acridinone dyes.

  Of the oil-soluble dyes that can be used in the present invention, any magenta dye can be used. For example, aryl or hetaryl azo dyes having phenols, naphthols, anilines as coupling components; for example, azomethine dyes having pyrazolones, pyrazolotriazoles as coupling components; for example arylidene dyes, styryl dyes, merocyanine dyes, oxonol dyes Methine dyes; carbonium dyes such as diphenylmethane dyes, triphenylmethane dyes and xanthene dyes; quinone dyes such as naphthoquinone, anthraquinone and anthrapyridone; condensed polycyclic dyes such as dioxazine dyes, etc. Can be mentioned.

  Among the oil-soluble dyes that can be used in the present invention, any cyan dye can be used. For example, indoaniline dyes, indophenol dyes or azomethine dyes having pyrrolotriazoles as coupling components; polymethine dyes such as cyanine dyes, oxonol dyes, merocyanine dyes; carbonium dyes such as diphenylmethane dyes, triphenylmethane dyes, xanthene dyes Phthalocyanine dyes; anthraquinone dyes; for example, aryl or heteryl azo dyes having phenols, naphthols and anilines as coupling components; indigo / thioindigo dyes;

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

  Although not limited to the following, preferred specific examples include C.I. I. Solvent Black 3, 7, 27, 29 and 34; C.I. I. Solvent Yellow 14, 16, 19, 29, 30, 56, 82, 93 and 162; C.I. I. Solvent Red 1, 3, 8, 18, 24, 27, 43, 49, 51, 72, 73, 109, 122, 132 and 218; I. Solvent Violet 3; C.I. I. Solvent Blue 2,11,25,35,38,67 and 70; I. Solvent Green 3 and 7; I. Solvent orange 2; and the like. Among these, particularly preferred are the Black Black PC-0850, Oil Black HBB, Oil Yellow 129, Oil Yellow 105, Oil Pink 312, Oil Red 5B, Oil Scallet 308, Vali Fast Blue chemistry 2606e Bile 2OSe 2B eO (Manufactured by Co., Ltd.), Aizen Spillon Blue GNH (manufactured by Hodogaya Chemical Co., Ltd.), Neopen Yellow 075, Neopen Magenta SE1378, Neopen Blue 808, Neopen Blue FF4012, and Neo42 Cy FF4012.

  In the present invention, a disperse dye can be used as long as it is soluble in a water-immiscible organic solvent. Preferred examples thereof include C.I. I. Disperse Yellow 5,42,54,64,79,82,83,93,99, 100,119,122,124,126,160,184: 1,186,198,199,201,204,224 and 237 C. I. Disperse Orange 13, 29, 31: 1, 33, 49, 54, 55, 66, 73, 118, 119 and 163; I. Disperse Red 54, 60, 72, 73, 86, 88, 91, 92, 93, 111, 126, 127, 134, 135, 143, 145, 152, 153, 154, 159, 164, 167: 1,177 , 181, 204, 206, 207, 221, 239, 240, 258, 277, 278, 283, 311, 323, 343, 348, 356 and 362; I. Disperse Violet 33; C.I. I. Disperse Blue 56, 60, 73, 87, 113, 128, 143, 148, 154, 158, 165, 165: 1, 165: 2, 176, 183, 185, 197, 198, 201, 214, 224, 225 , 257, 266, 267, 287, 354, 358, 365 and 368; I. Disperse Green 6: 1 and 9;

  Particularly preferred oil-soluble dyes include azo or azomethine dyes represented by the following formula (1) or (2). The dye represented by the following formula (2) is known as a dye formed from a coupler and a developing agent by oxidation in a photographic material.

In the above formulas (1) and (2), R ¹ , R ² , R ³ and R ⁴ are each independently a hydrogen atom, halogen atom, aliphatic group, aromatic group, heterocyclic group, cyano group, hydroxy group , Nitro group, amino group, alkylamino group, alkoxy group, aryloxy group, amide group, arylamino group, ureido group, sulfamoylamino group, alkylthio group, arylthio group, alkoxycarbonylamino group, sulfonamido group, carbamoyl Group, sulfamoyl group, sulfonyl group, alkoxycarbonyl group, heterocyclic oxy group, azo group, acyloxy group, carbamoyloxy group, silyloxy group, aryloxycarbonyl group, aryloxycarbonylamino group, imide group, heterocyclic thio group, sulfinyl Group, phosphoryl group, acyl group, carboxyl group or sulfo group Represents a group.

In the formulas (1) and (2), in particular, R ² is a hydrogen atom, a halogen atom, an aliphatic group, an alkoxy group, an aryloxy group, an amide group, a ureido group, or a sulfamoylamino group among the above substituents. It is preferably an alkoxycarbonylamino group or a sulfonamide group.

In the present invention, the aliphatic group means an alkyl group, a substituted alkyl group, an alkenyl group, a substituted alkenyl group, an alkynyl group, a substituted alkynyl group, an aralkyl group and a substituted aralkyl group. The aliphatic group may have a branch or may form a ring. The number of carbon atoms in the aliphatic group is preferably 1-20, and more preferably 1-18. The aryl part of the aralkyl group and the substituted aralkyl group is preferably phenyl or naphthyl, particularly preferably phenyl. Examples of the substituent of the alkyl moiety of the substituted alkyl group, the substituted alkenyl group, the substituted alkynyl group, and the substituted aralkyl group include the substituents exemplified in the description of R ^{1 to} R ⁴ . The example of the substituent of the aryl part of a substituted aralkyl group is the same as the example of the substituent of the following substituted aryl group.

In the present invention, the aromatic group means an aryl group and a substituted aryl group. The aryl group is preferably phenyl or naphthyl, particularly preferably phenyl. The aryl part of the substituted aryl group is the same as the above aryl group. Examples of the substituent of the substituted aryl group include the substituents exemplified in the description of R ^{1 to} R ⁴ .

In the formulas (1) and (2), A represents —NR ⁵ R ⁶ or a hydroxy group, and R ⁵ and R ⁶ each independently represents a hydrogen atom, an aliphatic group, an aromatic group, or a heterocyclic group. . A is preferably —NR ⁵ R ⁶ . R ⁵ and R ⁶ may be bonded to each other to form a ring. R ⁵ and R ⁶ are each preferably a hydrogen atom, an alkyl group, a substituted alkyl group, an aryl group or a substituted aryl group, each having a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, or 1 carbon atom. Most preferred is a substituted alkyl group of ˜18.

In the formulas (1) and (2), B ¹ represents = C (R ³ )-or = N-, and B ² represents -C (R ⁴ ) = or -N =. It is preferable that B ¹ and B ² are not simultaneously -N =, and it is more preferable that B ¹ is = C (R ³ )-and B ² is -C (R ⁴ ) =. Any of R ¹ and R ⁵ , R ³ and R ^6, and R ¹ and R ² may be bonded to each other to form an aromatic ring or a heterocyclic ring.

In the formula (1), Y represents an unsaturated heterocyclic group. Y is preferably a 5-membered or 6-membered unsaturated heterocyclic ring. The heterocyclic ring may be condensed with an aliphatic ring, an aromatic ring or another heterocyclic ring. N, O, and S can be mentioned as an example of the hetero atom of a heterocyclic ring.
Examples of the unsaturated heterocyclic ring include pyrazole ring, imidazole ring, thiazole ring, isothiazole ring, thiadiazole ring, thiophene ring, benzothiazole ring, benzoxazole ring, benzoisothiazole ring, pyrimidine ring, pyridine ring, and quinoline. A ring or the like is preferable. In addition, the unsaturated heterocyclic group may have the substituents exemplified in R ^{1 to} R ⁴ .

In the formula (2), X represents a color photographic coupler residue. The following are preferred as the residues of the color photographic coupler.
Yellow coupler: U.S. Pat. Nos. 3,933,501, 4,022,620, 4,326,024, 4,401,752, 4,248,961, and JP-B-58-10939 British Patents 1,425,020, 1,476,760, U.S. Patents 3,973,968, 4,314,023, 4,511,649, European Patent 249,473A, Couplers represented by formulas (I) and (II) of No. 502,424A, couplers represented by formulas (1) and (2) of No. 513,496A (particularly Y-28 on page 18), No. 568,037A, the coupler represented by the formula (I) of claim 1, US Pat. No. 5,066,576, column 1, line 45 to 55, the coupler represented by the general formula (I), General of paragraph 0008 of 274425 A coupler represented by (I), a coupler described in claim 1 on page 40 of European Patent 498,381A1 (particularly D-35 on page 18), and represented by formula (Y) on page 4 of 447,969A1. Couplers (especially Y-1 (page 17), Y-54 (page 41)), represented by the formulas (II) to (IV) in columns 7 to 58 of column 7 of US Pat. No. 4,476,219. Couplers (particularly II-17, 19 (column 17), II-24 (column 19)).

  Magenta couplers: US Pat. Nos. 4,310,619, 4,351,897, European Patent 73,636, US Pat. Nos. 3,061,432, 3,725,067, Research Disclosure No. 24220 (June 1984), ibid. 24230 (June 1984), JP-A-60-33552, JP-A-60-43659, JP-A-61-72238, JP-A-60-35730, JP-A-55-118034, JP-A-60-185951, U.S. Pat. No. 500,630, No. 4,540,654, No. 4,556,630, International Publication No. WO88 / 04795, JP-A-3-39737 (L-57 (page 11, lower right), L-68 (12 (Lower right of page), L-77 (lower right of page 13)), [A-4] -63 (page 134), [A-4] -73, -75 (page 139) of European Patent 456,257, 486, 965, M-4, -6 (page 26), M-7 (page 27), 571, 959A, M-45 (page 19), and JP-A-5-204106, M-1 (Page 6), paragraph 0237 M- 2, US Pat. No. 3,061,432 and No. 3,725,067.

  Cyan coupler: U.S. Pat. Nos. 4,052,212, 4,146,396, 4,228,233, 4,296,200, European Patent 73,636, Japanese Patent Laid-Open No. 4-204843 CX-1,3,4,5,11,12,14,15 (pages 14 to 16); JP-A-4-43345, C-7,10 (page 35), 34,35 (page 37), ( I-1), (I-17) (pages 42-43); a coupler represented by general formula (Ia) or (Ib) of claim 1 of JP-A-6-67385.

  Other couplers described in JP-A-62-215272 (page 91), JP-A-2-33144 (pages 3, 30), EP 355,660A (pages 4, 5, 45, 47) Is also useful.

  Of the oil-soluble dyes represented by the formula (1), a dye represented by the following formula (3) is particularly preferably used as the magenta dye.

In the formula (3), Z ¹ represents an electron-withdrawing group having a Hammett's substituent constant σp value of 0.20 or more. Z ¹ is preferably an electron-withdrawing group having a σp value of 0.30 or more and 1.0 or less. Preferred examples of the substituent include an electron-withdrawing substituent described later. Among them, an acyl group having 2 to 12 carbon atoms, an alkyloxycarbonyl group having 2 to 12 carbon atoms, a nitro group, a cyano group, An alkylsulfonyl group having 1 to 12 carbon atoms, an arylsulfonyl group having 6 to 18 carbon atoms, a carbamoyl group having 1 to 12 carbon atoms, and a halogenated alkyl group having 1 to 12 carbon atoms are preferable. Particularly preferred are a cyano group, an alkylsulfonyl group having 1 to 12 carbon atoms, and an arylsulfonyl group having 6 to 18 carbon atoms, and most preferred is a cyano group.

In the formula (3), Z ² represents a hydrogen atom, an aliphatic group or an aromatic group.
In said Formula (3), R < ¹ > -R < ⁶ > is synonymous with each of the said Formula (1).

In the formula (3), Q represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group. Among these, Q is preferably a group composed of a nonmetallic atom group necessary for forming a 5- to 8-membered ring. Among these, an aromatic group or a heterocyclic group is particularly preferable. The 5- to 8-membered ring may be substituted, may be a saturated ring, or may have an unsaturated bond. Preferred nonmetallic atoms include nitrogen atoms, oxygen atoms, sulfur atoms or carbon atoms. Specific examples of such a ring structure include, for example, a benzene ring, cyclopentane ring, cyclohexane ring, cycloheptane ring, cyclooctane ring, cyclohexene ring, pyridine ring, pyrimidine ring, pyrazine ring, pyridazine ring, triazine ring, imidazole ring. , A benzimidazole ring, an oxazole ring, a benzoxazole ring, an oxane ring, a sulfolane ring, a thiane ring, and the like. When these rings further have a substituent, the substituent is the substituent of the formula (1). group exemplified in R ¹ to R ⁴ can be mentioned.

  In addition, about the preferable structure of the compound represented by the said Formula (3), it describes in Unexamined-Japanese-Patent No. 2001-335714.

  Of the dyes represented by the formula (2), a dye represented by the following formula (4) is particularly preferably used as the magenta dye.

  In the above formula (4), G is a hydrogen atom, aliphatic group, aromatic group, heterocyclic group, cyano group, alkoxy group, aryloxy group, alkylthio group, arylthio group, ester group, amino group, carbamoyl group, sulfonyl group Represents a group, a sulfamoyl group, a ureido group, a urethane group, an acyl group, an amide group or a sulfonamide group.

In said formula (4), R < ¹ >, R < ² >, A, B < ¹ > and B < ² > are synonymous with each of said formula (2), and those preferable ranges are also the same.

  In the formula (4), L is an aliphatic group, aromatic group, heterocyclic group, cyano group, alkoxy group, aryloxy group, alkylthio group, arylthio group, ester group, amino group, carbamoyl group, sulfonyl group, sulfamoyl. Represents a group of atoms that form a 5- or 6-membered nitrogen-containing heterocycle optionally substituted with at least one of a group, a ureido group, a urethane group, an acyl group, an amide group, and a sulfonamide group, Further, a condensed ring may be formed with another ring.

In the compound represented by the formula (4), A is preferably —NR ⁵ R ⁶ , L preferably forms a 5-membered nitrogen-containing heterocyclic ring, and examples of the 5-membered nitrogen-containing heterocyclic ring include imidazole. Rings, triazole rings and terazole rings are included.

Examples of magenta dye compounds (M-0 to 6, a-21 to 25) among the dyes represented by the formula (1) and the formula (2) are shown below. It is for explaining in detail, and the present invention is not limited by these.
In the present invention, M-0, M-4, M-6, and a-21 can be used, and M-4, M-6, and a-21 can be particularly preferably used.

  Other examples of the colorant compound that can be used in the present invention are described in, for example, JP-A Nos. 2001-240763, 2001-181549, and JP-A-2001-335714. It is not limited to these.

  The compound represented by the formula (3) can be synthesized, for example, with reference to the methods described in JP-A No. 2001-335714 and JP-A No. 55-161856. The compound represented by the formula (4) can be referred to, for example, the methods described in JP-A-4-1267772 and JP-B-7-94180 and JP-A-2001-240763. Can be synthesized.

  Of the dyes represented by the formula (2), a pyrrolotriazole azomethine dye represented by the following formula (5) can be particularly preferably used as the cyan dye.

In the formula (5), A, R ¹ , R ² , B ¹ and B ² have the same meanings as those in the formula (2), and preferred ranges thereof are also the same.

In the formula (5), Z ³ and Z ⁴ are each independently synonymous with G in the formula (4). Z ³ and Z ⁴ may be bonded to each other to form a ring structure. It is more preferable that Z ³ is an electron-withdrawing group having a Hammett substituent constant σp value of 0.30 or more because the absorption is sharp. Z ³ is more preferably an electron-withdrawing group having a Hammett substituent constant σp value of 0.45 or more, and most preferably an electron-withdrawing group having a Hammett substituent constant σp value of 0.60 or more. And those having a sum of Hammett substituent constants σp values of Z ³ and Z ⁴ of 0.70 or more exhibit an excellent hue as cyan, and are more preferable.

In the formula (5), M is an atomic group forming a 1,2,4-triazole ring condensed with the 5-membered ring in the formula (5), and two atoms in the condensed part with the 5-membered ring One of B ³ and B ⁴ is a nitrogen atom and the other is a carbon atom.

  The compound represented by the formula (5) is preferably used as a cyan dye, but can also be used as a magenta dye by changing a substituent.

  Here, Hammett's substituent constant σp value used in this specification will be described. Hammett's rule is an empirical rule proposed by L. P. Hammett in 1935 to quantitatively discuss the effect of substituents on the reaction or equilibrium of benzene derivatives, which is widely accepted today. Substituent constants determined by Hammett's rule include σp value and σm value, and these values can be found in many general books. For example, JA Dean edition, “Lange's Handbook of Chemistry” 12th edition, 1979 (Mc Graw-Hill), “Chemical domain” extra edition, 122, 96-103, 1979 (Nankodo). In the present invention, each substituent is limited or explained by Hammett's substituent constant σp, but this is limited to only a substituent having a known value that can be found in the above-mentioned book. Needless to say, it also includes substituents that would be included in the range when measured based on Hammett's rule even if the value is unknown. The formulas (1) to (5) include those that are not benzene derivatives, but the σp value is used as a scale indicating the electronic effect of the substituent regardless of the substitution position. In the present invention, the σp value is used in this sense.

  Examples of the electron-withdrawing group having a Hammett substituent constant σp value of 0.60 or more include a cyano group, a nitro group, and an alkylsulfonyl group (for example, a methanesulfonyl group and an arylsulfonyl group (for example, a benzenesulfonyl group)). As the electron withdrawing group having a Hammett σp value of 0.45 or more, in addition to the above, an acyl group (for example, acetyl group), an alkoxycarbonyl group (for example, dodecyloxycarbonyl group), an aryloxycarbonyl group (for example, m-chlorophenoxy) Carbonyl), alkylsulfinyl group (for example, n-propylsulfinyl), arylsulfinyl group (for example, phenylsulfinyl), sulfamoyl group (for example, N-ethylsulfamoyl, N, N-dimethylsulfamoyl), halogenated alkyl group (For example, a trif (Loromethyl).

  As the electron-withdrawing group having a Hammett substituent constant σp value of 0.30 or more, in addition to the above, an acyloxy group (eg, acetoxy), a carbamoyl group (eg, N-ethylcarbamoyl, N, N-dibutylcarbamoyl), halogen Alkoxy group (for example, trifluoromethyloxy), halogenated aryloxy group (for example, pentafluorophenyloxy), sulfonyloxy group (for example, methylsulfonyloxy), halogenated alkylthio group (for example, difluoromethylthio), 2 An aryl group (eg, 2,4-dinitrophenyl, pentachlorophenyl) substituted with one or more electron-withdrawing groups having a σp value of 0.15 or more, and a heterocyclic ring (eg, 2-benzoxazolyl, 2- Benzothiazolyl, 1-phenyl-2-benzimidazolyl) Can do. Specific examples of the electron-withdrawing group having a σp value of 0.20 or more include a halogen atom in addition to the above.

  Moreover, in this invention, the oil-soluble dye represented by a following formula (AI) can be used preferably.

In formula (AI): X ₁ , X ₂ , X ₃ and X ₄ are each independently —SO—Z, —SO ₂ —Z, —SO ₂ NR ₁ R ₂ , —CONR ₁ R ₂ , It represents a group selected from -CO ₂ R ₁ and a sulfo group. Here, Z is a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted group. Represents a substituted heterocyclic group. R ₁ and R ₂ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted cycloalkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aralkyl group, substituted or unsubstituted It represents a substituted aryl group or a substituted or unsubstituted heterocyclic group. However, R ₁ and R ₂ are not both hydrogen atoms. M represents a hydrogen atom, a metal element, a metal oxide, a metal hydroxide, or a metal halide. Y ₁ , Y ₂ , Y ₃ and Y ₄ each independently represent a hydrogen atom or a monovalent substituent. _{a 1 ~a 4, b 1 ~b} 4 represents the number of _{X 1 ~X 4, Y 1 ~Y} 4, each independently, an integer of 0-4. However, the sum of a _{1 to} a ₄ is 2 or more.

  Of the oil-soluble dyes represented by the formula (AI), an oil-soluble dye represented by the following formula (A-II) can be particularly preferably used.

Formula (A-II) _{in: X 11 ~X 14, Y 11} ~Y 18 , and M are the same as _{X 1 ~X 4, Y 1 ~Y} 4, M in Formula (A-I) synonymous . a ₁₁ ~a ₁₄ each independently represent a integer of 1 or 2.

  Illustrative compound (AII-17) is shown as a specific example of formula (A-II), but this is for the purpose of illustrating the present invention in detail, and the present invention is not limited thereby. .

  In the present invention, it is preferable to use an oil-soluble dye having an oxidation potential nobler than 1.0 V (SCE). The oxidation potential is more preferable as it is noble, the oxidation potential is more noble than 1.1 V (SCE), more preferably 1.2 V (SCE).

  A person skilled in the art can easily measure the value of the oxidation potential (Eox). Regarding this method, for example, “New Instrumental Methods in Electrochemistry” by P. Delahay (1954, published by Interscience Publishers), “Electrochemical Methods” by AJ Bard et al. (1980, published by John Wiley & Sons), Akira Fujishima et al. It is described in the book "Electrochemical measurement method" (1984, published by Gihodo Publishing Co., Ltd.).

Specifically, the oxidation potential is 1 × 10 ⁻⁴ to 1 × 10 ⁻⁶ mol / in a solvent such as dimethylformamide or acetonitrile containing a supporting electrolyte such as sodium perchlorate or tetrapropylammonium perchlorate. Approximate the oxidization wave in a straight line by dissolving 1 liter and sweeping to the oxidation side (noble side) using carbon (GC) as the working electrode and rotating platinum electrode as the counter electrode by cyclic voltammetry and DC polarography equipment Then, the intermediate potential of the line segment formed by the intersection of this straight line and the residual 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) Values are measured as values for SCE (saturated calomel electrode). 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 ensured 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 electrolytes and solvents that can be used are described in Akira Fujishima et al., “Electrochemical measurement method” (1984, published by Gihodo Publishing Co., Ltd.), pages 101 to 118.
In the concentration range of the measurement solvent and the phthalocyanine compound sample, the oxidation potential in a non-association state is measured.

The value of Eox represents the ease of transfer of electrons from the sample to the electrode, and the greater the value (the higher the oxidation potential), the less transfer of electrons from the sample to the electrode, in other words, less oxidation.
When a dye having a low oxidation potential is used, polymerization inhibition by the dye is large and curability is lowered. When a dye having a noble oxidation potential is used, there is almost no polymerization inhibition.

The colorant that can be used in the present invention is preferably added to the ink composition of the present invention or the ink composition for inkjet recording and then appropriately dispersed in the ink. For dispersing the colorant, for example, a dispersion device such as a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, or a paint shaker can be used.
It is also possible to add a dispersant when dispersing the colorant. The type of the dispersant is not particularly limited, but a polymer dispersant is preferably used, and examples of the polymer dispersant include Solsperse series manufactured by Zeneca. Moreover, it is also possible to use a synergist according to various pigments as a dispersion aid. In the present invention, these dispersant and dispersion aid are preferably added in an amount of 1 to 50 parts by weight with respect to 100 parts by weight of the colorant.
The colorant may be added directly to the ink composition of the present invention, but may be added in advance to a dispersion medium such as a solvent or a polymerizable compound used in the present invention in order to improve dispersibility. In the present invention, in order to avoid the problem of deterioration of solvent resistance when the solvent remains in the cured image and the problem of VOC (Volatile Organic Compound) of the remaining solvent, the colorant is added to the polymerizable compound. It is preferable to add. Further, as the polymerizable compound to be used, it is preferable in view of dispersion suitability to select a monomer having the lowest viscosity.

  In the present invention, the average particle diameter of the colorant particles is preferably 0.005 to 0.5 μm, more preferably 0.01 to 0.45 μm, and still more preferably 0.015 to 0.3 μm. The maximum particle size of the colorant is preferably 0.3 to 10 μm, more preferably 0.3 to 3 μm. It is preferable to set the colorant, the dispersant, the dispersion medium, the dispersion conditions, and the filtration conditions so that the maximum particle diameter is obtained. This particle size control is preferable because clogging of the head nozzle can be suppressed and ink storage stability, ink transparency, and curing sensitivity can be maintained.

(D) Sensitizing dye The ink composition of the present invention, particularly when used for inkjet recording, absorbs specific actinic radiation and polymerizes from the specific cationic polymerization initiator or other polymerization initiator described later. A sensitizing dye may be added to promote the generation of active species. A sensitizing dye absorbs specific actinic radiation and enters an electronically excited state. The sensitizing dye in an electronically excited state comes into contact with the polymerization initiator, and effects such as electron transfer, energy transfer, and heat generation occur. As a result, the polymerization initiator undergoes a chemical change and decomposes to generate radicals, acids or bases.
Examples of preferred sensitizing dyes include those belonging to the following compounds and having an absorption wavelength in the 350 nm to 450 nm region.
For example, polynuclear aromatics (eg, pyrene, perylene, triphenylene), xanthenes (eg, fluorescein, eosin, erythrosine, rhodamine B, rose bengal), cyanines (eg, thiacarbocyanine, oxacarbocyanine), merocyanine (Eg, merocyanine, carbomerocyanine), thiazines (eg, thionine, methylene blue, toluidine blue), acridines (eg, acridine orange, chloroflavin, acriflavine), anthraquinones (eg, anthraquinone), squalium (eg, , Squalium), and coumarins (for example, 7-diethylamino-4-methylcoumarin).

  Preferred examples of the sensitizing dye that can be used in the present invention include compounds represented by the following formulas (vi) to (x).

In formula (vi), A ¹ represents a sulfur atom or NR ⁵⁰ , and R ⁵⁰ represents an alkyl group or an aryl group. L ¹ represents a nonmetallic atomic group that forms a basic nucleus of a dye 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 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 formula (vi).

In 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 represent a monovalent nonmetallic atomic group.

Wherein (ix), A ³ and A ⁴ are each independently -S -, - NR ^62-, or represents -NR ^63-, R ⁶² and R ⁶³ are each independently a substituted or unsubstituted An alkyl group or a substituted or unsubstituted aryl group is represented. L ⁴ and L ⁵ each independently represent a nonmetallic atomic group that forms a basic nucleus of a dye 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 formula (x), R ⁶⁶ represents an aromatic ring or a hetero ring which may have a substituent. A ⁵ denotes 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.

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

In formula (XII), A ³ and A ⁴ each independently represent —S—, —NR ⁶² — or —NR ⁶³ —, wherein R ⁶² and R ⁶³ each independently represent a substituted or unsubstituted alkyl group, substituted or represents an unsubstituted aryl group, L to ^5, L ⁶ are each independently, and in cooperation with the adjacent a ^3, A4 ^及 beauty adjacent carbon atoms represent a non-metallic atomic group forming a basic nucleus of a dye, R ⁶⁰ and R ⁶¹ are each independently a hydrogen atom or a monovalent nonmetallic atomic group, or can be bonded to each other to form an aliphatic or aromatic ring.

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

In the formula (XIV), R ₆₈ and R ₆₉ each independently represent a hydrogen atom or a monovalent nonmetallic atomic group, and R ₇₀ and R ₇₁ each independently represent a hydrogen atom or a monovalent nonmetallic atomic group. N represents an integer of 0 to 4. When n is 2 or more, R ₇₀ and R ₇₁ may be bonded to each other to form an aliphatic or aromatic ring.

  Specific preferred examples of the compounds represented by formulas (vi) to (XIV) include (C-1) to (C-26) shown below, but are not limited thereto. In addition, the structural formula in the following compound is described by a simplified structural formula, and a solid line represents a hydrocarbon chain.

The content of the (d) sensitizing dye in the ink composition of the present invention is preferably 0.01 to 20% by weight with respect to the total solid content of the ink composition, from the viewpoint of the colorability of the ink. More preferably, it is in the range of 0.5 to 10% by weight.
(D) A sensitizing dye may be used individually by 1 type, and may use 2 or more types together.
The content ratio of (d) the sensitizing dye and the above-mentioned (a) specific cationic polymerization initiator in the ink composition is a weight ratio from the viewpoint of improving the decomposition rate of the polymerization initiator and transmitting the irradiated light. Therefore, a / d = 100 to 0.5 is preferable, a / d = 50 to 1 is more preferable, and a / d = 10 to 1.5 is more preferable.

(E) Co-sensitizer The ink composition of the present invention preferably contains a co-sensitizer. In the present invention, the co-sensitizer has functions such as further improving the sensitivity of the sensitizing dye to actinic radiation or suppressing polymerization inhibition of the polymerizable compound by oxygen.
Examples of such co-sensitizers include amines such as MR Sander et al., “Journal of Polymer Society”, Vol. 10, page 3173 (1972), Japanese Examined Patent Publication No. 44-20189, Japanese Patent Laid-Open No. 51-82102. Publication, JP 52-134692, JP 59-138205, JP 60-84305, JP 62-18537, JP 64-33104, Research Disclosure 33825 Specifically, triethanolamine, p-dimethylaminobenzoic acid ethyl ester, p-formyldimethylaniline, p-methylthiodimethylaniline and the like can be mentioned.

  Other examples of co-sensitizers include thiols and sulfides, for example, thiol compounds described in JP-A-53-702, JP-B-55-500806, JP-A-5-142773, and JP-A-56. And the like. Specific examples include 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-mercaptobenzoimidazole, 2-mercapto-4 (3H) -quinazoline, β-mercaptonaphthalene. Etc.

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

(F) Other polymerizable compound In the ink composition of the invention, (b) a cationic polymerizable compound and another polymerizable compound may be used in combination. Examples of the polymerizable compound that can be used in combination with the present invention include radically polymerizable compounds. Examples of the radical polymerizable compound are described in JP-A-7-159983, JP-B-7-31399, JP-A-8-224982, JP-A-10-863, JP-A-7-231444, and the like. A photocurable material using a photopolymerizable composition that has been used is known.

  The radically polymerizable compound that can be used in the present invention is a compound having one or more carbon-carbon double bonds (ethylenically unsaturated bonds) capable of radical polymerization, and ethylenically unsaturated capable of radical polymerization in the molecule. Any compound having one bond may be used, including compounds having chemical forms such as monomers, oligomers and polymers. Only one kind of radically polymerizable compound may be used, or two or more kinds thereof may be used in combination at an arbitrary ratio in order to improve desired properties.

Examples of the polymerizable compound having an ethylenically unsaturated bond capable of radical polymerization include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, and salts thereof, Examples thereof include radically polymerizable compounds such as anhydrides having a saturated group, acrylonitrile, styrene, various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes.
Specifically, acrylic acid derivatives such as 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, butoxyethyl acrylate, carbitol acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, diacetone acrylamide, epoxy acrylate, methyl methacrylate, Examples include methacryl derivatives such as n-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, allyl methacrylate, glycidyl methacrylate, benzyl methacrylate, dimethylaminomethyl methacrylate, and other derivatives of allyl compounds such as allyl glycidyl ether. Is Yamashita Shinzo, “Crosslinking agent handbook” (1981 Taiseisha); Kato Vision, “UV / EB Curing Handbook (Raw Materials)” (1985, Polymer Publications); Radtech Study Group, “Application and Market of UV / EB Curing Technology”, p. 79, (1989, CMC) ); Commercially available products described in Eichiro Takiyama, “Polyester Resin Handbook”, (1988, Nikkan Kogyo Shimbun), or radically polymerizable or cross-linkable monomers, oligomers and polymers known in the industry can be used.
When a radically polymerizable compound and a cationically polymerizable compound are used in combination, a high sensitivity and a low volume shrinkage that is a characteristic of radical polymerization, and a printed material that has both high sensitivity and adhesion, or Since a lithographic printing plate is obtained, it is preferable.

(G) Other polymerization initiator The ink composition of the present invention may be used in combination with (a) a specific cationic polymerization initiator and (g) another polymerization initiator. Examples of the polymerization initiator used in combination include known radical polymerization initiators. The other polymerization initiators may be used alone or in combination of two or more.
The radical polymerization initiator that can be used in the ink composition of the present invention is a compound that absorbs external energy to generate a polymerization initiating species. External energy used for initiating polymerization is roughly divided into heat and actinic radiation, and a thermal polymerization initiator and a photopolymerization initiator are used, respectively. Examples of the active radiation include γ rays, β rays, electron beams, ultraviolet rays, visible rays, and infrared rays. The polymerization initiator that can be used in the present invention is preferably a radiation-sensitive radical polymerization initiator that is sensitive to actinic radiation, so-called photo radical polymerization initiator.

  Preferred radical polymerization initiators that can be used in combination with the present invention include (a) aromatic ketones, (b) organic peroxides, (c) thio compounds, (d) hexaarylbiimidazole compounds, (e) ketoxime esters. Compounds, (f) borate compounds, (g) azinium compounds, (h) metallocene compounds, (i) active ester compounds, (j) compounds having a carbon halogen bond, and (k) alkylamine compounds. These radical polymerization initiators may use the above compounds (a) to (k) alone or in combination.

(H) Other components Other components can be added to the ink composition of the present invention as necessary. Examples of other components include basic compounds, polymerization inhibitors, solvents, and cationic polymerizable monomers.
The basic compound is preferably added from the viewpoint of improving the storage stability of the ink composition. As the basic compound that can be used in the present invention, known basic compounds can be used. For example, basic inorganic compounds such as inorganic salts and basic organic compounds such as amines can be preferably used. .
The polymerization inhibitor is preferably added from the viewpoint of improving the storage stability. Further, when the ink composition of the present invention is used as an ink composition for ink jet recording, it is preferably discharged at a temperature in the range of 40 to 80 ° C. with a reduced viscosity, and also for preventing head clogging due to thermal polymerization. It is preferable to add a polymerization inhibitor. The polymerization inhibitor is preferably added in an amount of 200 to 20,000 ppm based on the total amount of the ink composition of the present invention. Examples of the polymerization inhibitor include hydroquinone, benzoquinone, p-methoxyphenol, TEMPO, TEMPOL, and cuperon Al.

In view of the fact that the ink composition of the present invention and the ink composition for ink jet recording are radiation curable ink compositions, it is preferable that no solvent is contained so that the ink composition can react quickly and be cured immediately after landing of the ink composition. However, a predetermined solvent can be included as long as the curing rate of the ink composition is not affected. In the present invention, an organic solvent or water can be used as the solvent. In particular, the organic solvent can be added in order to improve the adhesion to the recording medium (support such as paper). The addition of an organic solvent is effective because the problem of volatile organic compounds (VOC) can be avoided. The amount of the organic solvent is, for example, in the range of 0.1 to 5% by weight, preferably 0.1 to 3% by weight, based on the total weight of the ink composition of the present invention.
As a means for preventing a decrease in sensitivity due to the light-shielding effect of the colorant that can be used in the ink composition, in addition to a combination of a cationic polymerizable compound and a cationic polymerization initiator, and a combination of a radical polymerizable compound and a radical polymerization initiator Also, a radical-cation hybrid type curable ink using these polymerizable compounds and a polymerization initiator in combination may be used.

  In addition to this, a known compound can be added to the ink composition of the present invention as necessary. For example, surfactants, leveling additives, matting agents, polyester resins for adjusting film properties, polyurethane resins, vinyl resins, acrylic resins, rubber resins, waxes and the like are appropriately selected and added. be able to. In order to improve the adhesion to a recording medium such as polyolefin or PET, it is also preferable to contain a tackifier that does not inhibit the polymerization. Specifically, a high molecular weight adhesive polymer described in JP-A-2001-49200, pages 5 to 6 (for example, (meth) acrylic acid and an alcohol having an alkyl group having 1 to 20 carbon atoms). Ester, (meth) acrylic acid and a C3-14 alicyclic alcohol ester, (meth) acrylic acid and a C6-14 aromatic alcohol ester copolymer), and polymerizability Examples thereof include a low molecular weight tackifying resin having an unsaturated bond.

(2) Properties of Ink Composition As described above, the ink composition of the present invention includes (a) a cationic polymerization initiator represented by formula (I), and (b) a cationic polymerizable compound, and optionally It contains a colorant and the like. These components are preferably (a) a cationic polymerization initiator represented by formula (I) or formula (II), preferably 0.01 to 20 parts by weight, based on the total solid content of the entire ink composition. Preferably, 0.5 to 10 parts by weight, (b) the cationic polymerizable compound is preferably 10 to 95% by weight, more preferably 30 to 90% by weight, still more preferably 50 to 85% by weight, and a colorant. When used, the colorant is preferably contained in an amount of 1 to 10% by weight, more preferably 2 to 8% by weight, so that the total weight% of each component is 100% by weight. .

  When the obtained ink composition is used for inkjet recording, the viscosity of the ink composition is determined at a discharge temperature (for example, 40 to 80 ° C., preferably 25 to 30 ° C.) in consideration of discharge properties. , Preferably 7 to 30 mPa · s, more preferably 7 to 20 mPa · s. For example, the viscosity of the ink composition of the present invention at room temperature (25 to 30 ° C.) is preferably 35 to 500 mPa · s, more preferably 35 to 200 mPa · s. It is preferable that the composition ratio of the ink composition of the present invention is appropriately adjusted so that the viscosity is in the above range. By setting the viscosity at room temperature high, even when a porous recording medium is used, ink penetration into the recording medium can be avoided, and uncured monomers and odors can be reduced. Further, it is preferable because ink bleeding at the time of ink droplet landing can be suppressed, and as a result, the image quality is improved.

  The surface tension of the ink composition of the present invention is, for example, preferably 20 to 30 mN / m, more preferably 23 to 28 mN / m. When recording on various recording media such as polyolefin, PET, coated paper, and non-coated paper, 20 mN / m or more is preferable from the viewpoint of bleeding and penetration, and the wettability is preferably 30 mN / m or less.

(3) Inkjet recording method and apparatus The ink composition of the present invention is preferably used for inkjet recording.
An ink jet recording method that can be suitably employed in the present invention will be described below.

(3-1) Inkjet recording method The present invention ejects the ink composition onto a recording medium (support, recording material, etc.) and irradiates the ink composition ejected onto the recording medium with active radiation. Thus, a method for forming an image by curing ink is provided. That is, the present invention
(A) a step of discharging the ink composition onto a recording medium; and (b) a step of irradiating the discharged ink composition with active radiation to cure the ink composition;
An inkjet recording method comprising:
The present invention relates to an ink jet recording method in which the ink composition is the ink composition of the present invention.
The cured ink composition forms an image on the recording medium.
The peak wavelength of the active radiation is preferably 200 to 600 nm, more preferably 300 to 450 nm, and more preferably 350 to 420 nm. The output of active radiation is preferably 2,000 mJ / cm ² or less, more preferably from 10 to 2,000 mJ / cm ^2, more preferably, be 20 to 1,000 mJ / cm ² Particularly preferably, it is 50 to 800 mJ / cm ² .

Further, the ink jet recording method of the present invention will be described by taking as an example a method for producing a lithographic printing plate including forming an image by discharging an ink composition onto the lithographic printing plate.
The lithographic printing plate of the present invention has a hydrophilic support and a hydrophobic image formed on the hydrophilic support. The method for producing the lithographic printing plate comprises the following steps:
(A) a step of discharging the ink composition of the present invention onto a hydrophilic support; and
(B) A step of irradiating the discharged ink composition with actinic radiation to cure the ink composition, thereby forming a hydrophobic image formed by curing the ink composition on the hydrophilic support. ,
including.

(3-1-1) Hydrophilic support used for lithographic printing plate Here, the lithographic printing plate has a support and an image formed on the support.
Conventionally, so-called PS plates having a configuration in which a lipophilic photosensitive resin layer is provided on a hydrophilic support have been widely used as lithographic printing plates. As a method for producing the PS plate, a desired printing plate is usually obtained by performing mask exposure (surface exposure) through a lith film and then dissolving and removing the non-exposed portion. However, in recent years, digitization technology that electronically processes, stores, and outputs image information using a computer has become widespread, and a new image output method corresponding to the technology has been demanded. In particular, computer-to-plate (CTP) technology has been developed that scans highly-preferred light such as laser light according to digitized image information without using a lithographic film, and directly produces a printing plate. Yes.
Examples of a method for obtaining a lithographic printing plate that enables such scanning exposure include a method of directly producing a lithographic printing plate using an ink composition or an ink composition for ink jet recording. This is because ink is ejected onto a support, preferably a hydrophilic support, by an ink jet method or the like, and exposed to actinic radiation, whereby the ink composition or the ink for ink jet recording is exposed to a desired portion. A printing plate having an image (preferably a hydrophobic image) is obtained. An ink composition or ink jet recording ink suitable for such a system is the ink composition or ink jet recording ink of the present invention.
The support (recording medium) onto which the ink composition or ink for ink jet recording of the present invention is discharged is not particularly limited as long as it is a dimensionally stable plate-like support. The support is preferably a hydrophilic support. For example, paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, cellulose diacetate, cellulose triacetate, cellulose propionate) Cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), paper or plastic film on which the above-mentioned metal is laminated or deposited. A preferable support includes a polyester film and an aluminum plate. Among these, an aluminum plate that has good dimensional stability and is relatively inexpensive is preferable.

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

The thickness of the support is preferably from 0.1 to 0.6 mm, more preferably from 0.15 to 0.4 mm.
Prior to using the aluminum plate, it is preferable to perform surface treatment such as roughening treatment or anodizing treatment. By the surface treatment, it is easy to improve hydrophilicity and secure adhesion between the image recording layer and the support. Prior to roughening the aluminum plate, a degreasing treatment with a surfactant, an organic solvent, an alkaline aqueous solution or the like for removing rolling oil on the surface is performed as desired.

The surface roughening treatment of the aluminum plate is performed by various methods. For example, mechanical surface roughening treatment, electrochemical surface roughening treatment (surface roughening treatment for dissolving the surface electrochemically), chemical treatment, etc. Surface roughening treatment (roughening treatment that chemically selectively dissolves the surface).
As a method for the mechanical surface roughening treatment, a known method such as a ball polishing method, a brush polishing method, a blast polishing method, or a buff polishing method can be used. Also, a transfer method in which the uneven shape is transferred with a roll provided with unevenness in the aluminum rolling step may be used.
Examples of the electrochemical surface roughening treatment include a method in which an alternating current or a direct current is used in an electrolytic solution containing an acid such as hydrochloric acid or nitric acid. Another example is a method using a mixed acid as described in JP-A-54-63902.
The surface-roughened aluminum plate is subjected to an alkali etching treatment using an aqueous solution of potassium hydroxide, sodium hydroxide or the like, if necessary, further neutralized, and if desired, wear resistant. In order to increase the anodic oxidation treatment.

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

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

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

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

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

Suitable examples of the phosphate compound include phosphates of metals such as alkali metals and alkaline earth metals.
Specifically, for example, zinc phosphate, aluminum phosphate, ammonium phosphate, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, monoammonium phosphate, monopotassium phosphate, monosodium phosphate, dihydrogen phosphate Potassium, dipotassium hydrogen phosphate, calcium phosphate, sodium ammonium hydrogen phosphate, magnesium hydrogen phosphate, magnesium phosphate, ferrous phosphate, ferric phosphate, sodium dihydrogen phosphate, sodium phosphate, hydrogen phosphate Disodium, lead phosphate, diammonium phosphate, calcium dihydrogen phosphate, lithium phosphate, phosphotungstic acid, ammonium phosphotungstate, sodium phosphotungstate, ammonium phosphomolybdate, sodium phosphomolybdate, sodium phosphite , Tripolyphosphate Potassium, and sodium pyrophosphate. Of these, sodium dihydrogen phosphate, disodium hydrogen phosphate, potassium dihydrogen phosphate, and dipotassium hydrogen phosphate are preferable.
The combination of the inorganic fluorine compound and the phosphate compound is not particularly limited, but the aqueous solution contains at least sodium zirconate fluoride as the inorganic fluorine compound and contains at least sodium dihydrogen phosphate as the phosphate compound. Is preferred.
The concentration of the phosphate compound in the aqueous solution is preferably 0.01% by weight or more, more preferably 0.1% by weight or more, from the viewpoint of improving on-press developability and stain resistance. Further, in terms of solubility, it is preferably 20% by weight or less, and more preferably 5% by weight or less.

The ratio of each compound in the aqueous solution is not particularly limited, but the weight ratio of the inorganic fluorine compound and the phosphate compound is preferably 1/200 to 10/1, and preferably 1/30 to 2/1. Is more preferable.
The temperature of the aqueous solution is preferably 20 ° C. or higher, more preferably 40 ° C. or higher, preferably 100 ° C. or lower, more preferably 80 ° C. or lower.
The aqueous solution preferably has a pH of 1 or more, more preferably has a pH of 2 or more, preferably has a pH of 11 or less, and more preferably has a pH of 5 or less.
The method for sealing with an aqueous solution containing an inorganic fluorine compound is not particularly limited, and examples thereof include an immersion method and a spray method. These may be used alone or in combination, or may be used in combination of two or more.
Of these, the dipping method is preferred. When the treatment is performed using the dipping method, the treatment time is preferably 1 second or longer, more preferably 3 seconds or longer, and preferably 100 seconds or shorter, and 20 seconds or shorter. More preferred.

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

<Sealing treatment with hot water>
Examples of the sealing treatment with water vapor include a method in which an aluminum plate on which an anodized film is formed is immersed in hot water.
The hot water may contain an inorganic salt (for example, phosphate) or an organic salt.
The temperature of the hot water is preferably 80 ° C. or higher, more preferably 95 ° C. or higher, and preferably 100 ° C. or lower.
Further, the time of immersion in hot water is preferably 1 second or longer, more preferably 3 seconds or longer, more preferably 100 seconds or shorter, and even more preferably 20 seconds or shorter.
Examples of the hydrophilization treatment used in the present invention include US Pat. Nos. 2,714,066, 3,181,461, 3,280,734, and 3,902,734. There is an alkali metal silicate method as described in the book. In this method, the support is immersed in an aqueous solution such as sodium silicate or electrolytically treated. In addition, the treatment with potassium zirconate fluoride described in JP-B 36-22063, U.S. Pat. Nos. 3,276,868, 4,153,461 and 4,689, And a method of treating with polyvinylphosphonic acid as described in each specification of No.272.
In the present invention, the support preferably has a center line average roughness of 0.10 to 1.2 μm. Within this range, good adhesion to the image recording layer, good printing durability and good stain resistance are obtained, which is preferable.

(3-1-2) Step of discharging the ink composition onto the hydrophilic support When the ink composition of the present invention or the ink composition for inkjet recording is discharged onto the surface of the hydrophilic support, the ink composition The ink composition or ink composition for inkjet recording is preferably heated to 40 to 80 ° C., more preferably 25 to 30 ° C., and the viscosity of the ink composition is preferably 7 to 30 mPa · s, more preferably 7 to 20 mPa · s. It is preferable that the ink is discharged after being lowered. In particular, the use of an ink composition having an ink viscosity of 35 to 500 mP · s at 25 ° C. is preferable because a great effect can be obtained. By using this method, high ejection stability can be realized. A radiation curable ink composition such as the ink composition of the present invention generally has a higher viscosity than a water-based ink that is usually used in an ink composition or an ink for inkjet recording. The ink viscosity fluctuation has a great influence on the change of the droplet size and the change of the droplet discharge speed, and causes the image quality deterioration. Therefore, it is necessary to keep the temperature of the ink at the time of ejection as constant as possible. Therefore, in the present invention, it is appropriate that the temperature control range is set to ± 5 ° C. of the set temperature, preferably ± 2 ° C. of the set temperature, more preferably set temperature ± 1 ° C.

(3-1-3) Irradiating actinic radiation to the ejected ink composition to cure the ink composition, whereby a hydrophobic image formed by curing the ink composition is formed on the hydrophilic support. Step of forming the ink composition ejected on the surface of the hydrophilic support is cured by irradiation with actinic radiation. This is because the sensitizing dye in the polymerization initiation system contained in the ink composition of the present invention absorbs actinic radiation to be in an excited state, and the polymerization initiator is decomposed by contact with the polymerization initiator in the polymerization initiation system. This is because the polymerizable compound is cured by radical polymerization.
Here, α rays, γ rays, electron beams, X rays, ultraviolet rays, visible light, infrared rays, or the like can be used as the active radiation used. The peak wavelength of the actinic radiation is, for example, from 200 to 600 nm, preferably from 300 to 450 nm, more preferably from 350 to 450 nm, although it depends on the absorption characteristics of the sensitizing dye. In the present invention, the polymerization initiation system has sufficient sensitivity even with a low-power active radiation. Thus, the output of the actinic radiation is, for example, 2,000 mJ / cm ² or less, preferably, 10 to 2,000 mJ / cm ^2, more preferably, 20 to 1,000 mJ / cm ^2, more preferably, 50 to 800 mJ An irradiation energy of / cm ² is appropriate. The active radiation, the illumination intensity on the exposed surface is, for example, 10 to 2,000 mW / cm ^2, preferably, it is suitable to be irradiated at 20 to 1,000 mW / cm ^2.

The ink composition of the present invention is appropriately irradiated with such actinic radiation, for example, for 0.01 to 120 seconds, and preferably for 0.1 to 90 seconds.
Actinic radiation irradiation conditions and a basic irradiation method are disclosed in JP-A-60-132767. Specifically, the light source is provided on both sides of the head unit including the ink ejection device, and the head unit and the light source are scanned by a so-called shuttle method. Irradiation with actinic radiation takes a certain time (for example, 0.01 to 0.5 seconds, preferably 0.01 to 0.3 seconds, more preferably 0.01 to 0.15 seconds) after ink landing. Will be done. In this way, by controlling the time from ink landing to irradiation to an extremely short time, it is possible to prevent the ink that has landed on the recording medium from spreading before curing. Further, since the ink can be exposed to a porous recording medium before the ink penetrates to a deep part where the light source does not reach, residual unreacted monomer can be suppressed, and as a result, odor can be reduced. .
Further, the curing may be completed by another light source that is not driven. In WO99 / 54415, as an irradiation method, a method using an optical fiber or a method in which a collimated light source is applied to a mirror surface provided on the side surface of the head unit to irradiate the recording unit with UV light is disclosed.

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

(3-2) Inkjet recording apparatus There is no restriction | limiting in particular as an inkjet recording apparatus used for this invention, A commercially available inkjet recording apparatus can be used. That is, in the present invention, recording can be performed on a recording medium using a commercially available inkjet recording apparatus.
Examples of the ink jet recording apparatus that can be used in the present invention include an ink supply system, a temperature sensor, and an actinic radiation source.
The ink supply system includes, for example, an original tank containing the ink composition of the present invention, a supply pipe, an ink supply tank immediately before the inkjet head, a filter, and a piezo-type inkjet head. The piezo-type inkjet head has a multi-size dot of 1 to 100 pl, preferably 8 to 30 pl, for example, 320 × 320 to 4,000 × 4,000 dpi, preferably 400 × 400 to 1,600 × 1,600 dpi. More preferably, it can be driven so as to discharge at a resolution of 720 × 720 dpi. In the present invention, dpi represents the number of dots per 2.54 cm.

  As described above, since it is desirable that the radiation curable ink has a constant temperature for the ejected ink, heat insulation and heating can be performed from the ink supply tank to the inkjet head portion. The temperature control method is not particularly limited, but for example, it is preferable to provide a plurality of temperature sensors at each piping site and perform heating control according to the ink flow rate and the environmental temperature. The temperature sensor can be provided near the ink supply tank and the nozzle of the inkjet head. Moreover, it is preferable that the head unit to be heated is thermally shielded or insulated so that the apparatus main body is not affected by the temperature from the outside air. In order to shorten the printer start-up time required for heating or to reduce the loss of thermal energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

As the active radiation source, a mercury lamp, a gas / solid laser or the like is mainly used, and a mercury lamp and a metal halide lamp are widely known as the ultraviolet light curable ink jet. However, from the viewpoint of environmental protection, mercury-free is strongly desired, and replacement with a GaN-based semiconductor ultraviolet light-emitting device is very useful industrially and environmentally. Furthermore, LED (UV-LED) and LD (UV-LD) are small, have a long life, have high efficiency, and are low in cost, and are expected as light sources for photocurable ink jets.
Further, a light emitting diode (LED) and a laser diode (LD) can be used as the active radiation source. In particular, when an ultraviolet light source is required, an ultraviolet LED and an ultraviolet LD can be used. For example, Nichia Corporation has introduced a purple LED whose main emission spectrum has a wavelength between 365 nm and 420 nm. When even shorter wavelengths are required, US Pat. No. 6,084,250 discloses an LED that can emit actinic radiation centered between 300 nm and 370 nm. Other ultraviolet LEDs are also available and can emit radiation in different ultraviolet bands. The actinic radiation source particularly preferred in the present invention is a UV-LED, particularly preferably a UV-LED having a peak wavelength at 350 to 420 nm.
It is preferable that maximum illumination intensity of the LED on a recording medium is 10 to 2,000 mW / cm ^2, more preferably 20 to 1,000 mW / cm ^2, particularly preferably 50 to 800 mW / cm ² .

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these examples.
IRGACURE 250 and Darocur ITX (polymerization initiator) used in the present invention are commercial products manufactured by Ciba Specialty Chemicals (CSC).
In addition, for the reagents used in the synthesis of the compounds, and for which the manufacturer or production method is not specified, commercially available products such as Tokyo Chemical Industry Co., Ltd., Aldrich, etc. were used, or synthesis was performed by known methods. did.

[Synthesis Example of Compound Represented by Formula (I) or Formula (II)]
(Synthesis Example 1)
3.0 g of 9-chloromethylanthracene, 3.2 g of potassium carbonate, 6.5 g of bis (4-chlorophenyl) -4-hydroxyphenylsulfonium bromide and 100 mg of potassium iodide are added to 50 ml of dimethylacetamide, and the mixture is stirred at 80 ° C. for 6 hours. did. After allowing to cool, the reaction solution was poured into 100 ml of distilled water, and the precipitated crystals were filtered. Subsequently, dissolved in methanol 50 ml, a dropping funnel and added dropwise to an aqueous solution prepared by dissolving KPF ₆ 7.3 g of distilled water 500 ml. The precipitated crystals were washed with 30 ml of distilled water three times, then collected by filtration and dried with a vacuum pump for 6 hours to obtain 2.4 g of Compound A.

(Synthesis Example 2)
Compound B was synthesized in the same manner as Compound A except that bis (4-chlorophenyl) -4-hydroxyphenylsulfonium bromide in the synthesis method of Compound A was replaced with diphenyl-4-hydroxyphenylsulfonium bromide.

(Synthesis Example 3)
Compound C was synthesized in the same manner as Compound A except that 9-chloromethylanthracene in the synthesis method of Compound A was replaced with 9-butoxy-10-chloromethylanthracene.

(Synthesis Example 4)
1-bromoacetylanthracene (J Polymer Sci: Part A: Compound D was synthesized by using the method described in Polymer Chemistry, 38, 1433-1442 (2000).

<< Preparation of pigment dispersion >>
According to the method described below, yellow, magenta, cyan and black pigment dispersions 1 were prepared. The dispersion conditions are adjusted appropriately using a known dispersion device so that the average particle diameter of each pigment particle is in the range of 0.2 to 0.3 μm, and then filtered under heating. Prepared by filtration.
(Yellow pigment dispersion 1)
・ C. I. Pigment Yellow 13 20 parts by weight Polymer dispersing agent (Solsperse series manufactured by Zeneca) 20 parts by weight OXT-221 (manufactured by Toagosei Co., Ltd.) 60 parts by weight (magenta pigment dispersion 1)
・ C. I. Pigment Red 57: 1 20 parts by weight Polymer dispersing agent (Solsperse series manufactured by Zeneca) 20 parts by weight OXT-221 (manufactured by Toagosei Co., Ltd.) 60 parts by weight (cyan pigment dispersion 1)
・ C. I. Pigment Blue 15: 3 20 parts by weight Polymer dispersing agent (Solsperse series manufactured by Zeneca) 20 parts by weight OXT-221 (manufactured by Toagosei Co., Ltd.) 60 parts by weight (Black pigment dispersion 1)
・ C. I. Pigment Black 7 20 parts by weight / polymer dispersing agent (Solsperse series manufactured by Zeneca) 20 parts by weight / OXT-221 (manufactured by Toagosei Co., Ltd.) 60 parts by weight

<Preparation of ink>
Example 1
(Yellow ink 1)
Yellow pigment dispersion 1 5 parts by weight Compound A 6 parts by weight Polymerizable compound Monomer: 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate (Celoxide 2021A: manufactured by Daicel UCB)
40 parts by weight Monomer: 3,7-bis (3-oxetanyl) -5-oxanonane (OXT-221: manufactured by Toagosei Co., Ltd.) 48 parts by weight Basic compound: a-1 (Amine-1 below) 1 part by weight

(Magenta ink 1)
Magenta pigment dispersion 1 5 parts by weight Compound A 6 parts by weight Polymerizable compound Monomer: 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate (Celoxide 2021A: manufactured by Daicel UCB)
40 parts by weight Monomer: 3,7-bis (3-oxetanyl) -5-oxanonane (OXT-221: manufactured by Toagosei Co., Ltd.) 48 parts by weight Basic compound: 1 part by weight of the above a-1

(Cyan ink 1)
Cyan pigment dispersion 1 5 parts by weight Compound A 6 parts by weight Polymerizable compound Monomer: 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate (Celoxide 2021A: manufactured by Daicel UC Corporation)
40 parts by weight Monomer: 3,7-bis (3-oxetanyl) -5-oxanonane (OXT-221: manufactured by Toagosei Co., Ltd.) 48 parts by weight Basic compound: 1 part by weight of the above a-1

(Black ink 1)
Black pigment dispersion 1 5 parts by weight Compound A 6 parts by weight Polymerizable compound Monomer: 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxycyclohexanecarboxylate (Celoxide 2021A: manufactured by Daicel UCB)
40 parts by weight Monomer: 3,7-bis (3-oxetanyl) -5-oxanonane (OXT-221: manufactured by Toagosei Co., Ltd.) 48 parts by weight Basic compound: 1 part by weight of the above a-1

<Inkjet image recording>
Next, recording on a recording medium was performed using a commercially available inkjet recording apparatus having a piezoelectric inkjet nozzle. The ink supply system was composed of an original tank, supply piping, an ink supply tank immediately before the inkjet head, a filter, and a piezo-type inkjet head, and heat insulation and heating were performed from the ink supply tank to the inkjet head portion. Temperature sensors were provided near the ink supply tank and the nozzles of the ink jet head, respectively, and temperature control was performed so that the nozzle portions were always 70 ° C. ± 2 ° C. The piezo-type inkjet head was driven so that 8 to 30 pl multi-size dots could be ejected at a resolution of 720 × 720 dpi. After landing, UV light was condensed to an exposure surface illuminance of 100 mW / cm ² , and the exposure system, main scanning speed, and ejection frequency were adjusted so that irradiation started 0.1 seconds after ink landed on the recording medium. Further, the exposure time was variable, and exposure energy was irradiated. In the present invention, dpi represents the number of dots per 2.54 cm.

Using each of the color inks prepared above, the ink was emitted in the order of black → cyan → magenta → yellow at an environmental temperature of 25 ° C., and ultraviolet rays were irradiated for each color by a metal halide lamp Vzero085 manufactured by Integration Technology. In order to eliminate tackiness by palpation, the exposure was performed at a total exposure energy per color of 200 mJ / cm ² as a complete curing energy. As recording media, each color image was recorded on a grained aluminum support, a transparent biaxially stretched polypropylene film having a printability, a soft vinyl chloride sheet, cast coated paper, and commercially available recycled paper. However, in both cases, a high-resolution image without dot bleeding was obtained. Furthermore, even on high-quality paper, the ink was sufficiently cured without causing the ink to turn around, and there was almost no odor due to unreacted monomers. Further, the ink recorded on the film had sufficient flexibility, and the ink was not cracked even when it was bent, and there was no problem in the adhesion test by peeling the cello tape (registered trademark).

(Examples 2-8 and Comparative Examples 1-3)
The magenta ink 1 produced in Example 1 was used as Example 2.
<Preparation of ink>
Magenta inks 2-9 were prepared according to the method described below.

(Example 3: Magenta ink 2)
Magenta ink 2 was prepared in the same manner as magenta ink 1 except that compound B was used instead of compound A.

(Example 4: Magenta ink 3)
Magenta ink 3 was prepared in the same manner as magenta ink 1 except that compound C was used instead of compound A.

(Example 5: Magenta ink 4)
Magenta ink 4 was prepared in the same manner as magenta ink 1 except that compound D was used instead of compound A.

(Comparative Example 1: Magenta ink 5)
Magenta pigment dispersion 1 5 parts by weight Initiator UVI-6992 (manufactured by Dow Chemical Co.) 6 parts by weight Sensitizing dye: 3 parts by weight anthracene Polymerizable compound Monomer: 3,4-epoxycyclohexylmethyl-3 ′, 4′-epoxy Cyclohexane carboxylate (Celoxide 2021A: manufactured by Daicel UCB)
40 parts by weight Monomer: 3,7-bis (3-oxetanyl) -5-oxanonane (OXT-221: manufactured by Toagosei Co., Ltd.) 45 parts by weight Basic compound: 1 part by weight of the above a-1

(Comparative Example 2: Magenta ink 6)
Magenta ink 6 was prepared in the same manner as magenta ink 5 except that the initiator UVI-6992 (manufactured by Dow Chemical Company) was replaced with the initiator IRGACURE 250.

(Comparative Example 3: Magenta ink 7)
Magenta ink 20 was prepared in the same manner as magenta ink 19 except that Darocur ITX was used instead of anthracene.

(Example 6: Magenta ink 8)
Instead of magenta pigment dispersion 1, it was prepared in the same manner as magenta ink 1 except that the following compound M-1 (oxidation potential +1.37 V) was used as an oil-soluble dye, and filtered with a filter having an absolute filtration accuracy of 2 μm. And magenta ink 8.

(Example 7: Magenta ink 9)
Instead of the magenta pigment dispersion 1, it was prepared in the same manner as the magenta ink 1 except that the following compound M-2 (oxidation potential +0.94 V) was used as an oil-soluble dye, and filtered through a filter having an absolute filtration accuracy of 2 μm. And magenta ink 9.

  Crude magenta inks 2 to 9 prepared as described above were filtered through a filter having an absolute filtration accuracy of 2 μm to obtain magenta inks 2 to 9, respectively.

(Example 8 and Comparative Example 4: Image Production Using Light-Emitting Diode (LED))
(Example 8)
Using the magenta ink 1, a magenta image was produced in the same manner as described in Example 1 except that an ultraviolet light emitting diode (UV-LED) was used instead of the metal halide lamp Vzero085 manufactured by Integration Technology. .
In this example, NCCU033 manufactured by Nichia Chemical was used as the UV-LED. The LED outputs ultraviolet light having a wavelength of 365 nm from one chip. When a current of about 500 mA is applied, light of about 100 mW is emitted from the chip. A plurality of these are arranged at intervals of 7 mm, and a power of 0.3 W / cm ² can be obtained on the surface of a recording medium (hereinafter also referred to as a medium). The exposure time after the droplet ejection and the exposure time can be changed according to the transport speed of the medium and the distance between the head and the LED in the transport direction. In this embodiment, the exposure is performed about 0.5 seconds after landing.
Depending on the setting of the distance to the medium and the conveyance speed, the exposure energy on the medium can be adjusted between 0.01 and 15 J / cm ² .

(Comparative Example 4)
A magenta image was produced using the magenta ink 5 in the same manner as in Example 8.

<Evaluation of inkjet image>
For each formed image, in accordance with the method described above, sensitivity required for curing, permeability in commercially available recycled paper, ink bleeding on grained aluminum support, adhesion, printing durability, storage stability Was evaluated. In addition, as an index of printing durability, Example 2 was evaluated as 100.

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

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

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

(Evaluation of adhesion in grained aluminum support)
For the printed image created above, in accordance with JIS K 5400, a sample that does not scratch the printed surface at all, and has 11 cuts on the printed surface at 1 mm intervals vertically and horizontally. 100 samples were prepared, and a cellophane tape was affixed on each printing surface, quickly peeled off at an angle of 90 degrees, and the state of printed images or grids remaining without peeling was evaluated according to the following criteria.
○: No peeling of the printed image was observed even in the cross cut test. Δ: Some ink peeling was observed in the cross cut test, but almost no peeling was observed unless the ink surface was scratched. Easy to peel off with cello tape (registered trademark)

(Evaluation of printing durability)
The image printed on the grained aluminum support created above was used as a printing plate, and after printing with a Heidel KOR-D machine, the number of finished sheets was compared relative to each other as an index of printing durability (Example 2 was set to 100). ). A larger numerical value is preferable because it has a higher printing durability.

(Evaluation of storage stability)
The prepared ink was stored at 75% RH and 60 ° C. for 3 days, and then the ink viscosity at the injection temperature was measured. The increase in the ink viscosity was expressed as the viscosity ratio after storage / before storage. When the viscosity does not change and is close to 1.0, the storage stability is good, and when it exceeds 1.5, clogging may occur at the time of injection, which is not preferable.
These evaluation results are shown in Table 2.

  From Table 2, an ink composition comprising (a) a cationic polymerization initiator represented by formula (I) or (II) of the present invention, and (b) a cationic polymerizable compound, It is highly sensitive to radiation irradiation, can form high-quality images in terms of image-forming properties on paper, has good storage stability, and is used in the production of printing plates. It can also be seen that it is possible to form images with high printing durability and high image quality.

Claims (10)

(A) a cationic polymerization initiator represented by the following formula (I) or formula (II), and
(B) An ink composition comprising a cationically polymerizable compound.

(In formula (I) or formula (II), Ar represents a group obtained by removing (n + 1) hydrogen atoms from a condensed polycyclic aromatic ring, L represents a single bond or a divalent linking group, and R ^{1 to} R ⁴ independently represents a monovalent organic group, X ⁻ represents a conjugate base of an organic acid or an inorganic acid, the substitution number n of R ¹ represents an integer of 0 or more, and the substitution number m of R ² is 0. The number of substitution p of R ³ represents an integer of 0 to 5, and the number of substitution q of R ⁴ represents an integer of 0 to 5. However, one end of L is an arbitrary number on the benzene ring. And R ^{2 to} R ⁴ are bonded at any position on the benzene ring.)   The ink composition according to claim 1, wherein the ink composition contains a colorant.   The ink composition according to claim 2, wherein the colorant is a pigment or an oil-soluble dye.   The ink composition according to claim 3, wherein the oxidation potential of the oil-soluble dye is 1.0 V (vs SCE) or more.   The ink composition according to any one of claims 1 to 4, which is for inkjet recording. (A) a step of discharging an ink composition onto a recording medium; and
(B) a step of irradiating the discharged ink composition with actinic radiation to cure the ink composition;
An inkjet recording method comprising:
The ink-jet recording method, wherein the ink composition is the ink composition according to any one of claims 1 to 5. The active radiation is ultraviolet light emitted by a light emitting diode that generates ultraviolet light having an emission peak wavelength in the range of 350 to 420 nm and a maximum illuminance on the surface of the recording medium of 10 to 2,000 mW / cm ^2. The ink jet recording method according to claim 6.   Printed matter recorded by the ink jet recording method according to claim 6 or 7. (A) a step of discharging the ink composition according to any one of claims 1 to 5 onto a hydrophilic support; and
(B) A step of irradiating the discharged ink composition with actinic radiation to cure the ink composition, thereby forming a hydrophobic image formed by curing the ink composition on the hydrophilic support. ,
A method for producing a lithographic printing plate comprising   A lithographic printing plate produced by the lithographic printing plate production method according to claim 9.