JP2010018703A - Ink composition, ink set, inkjet recording method, printed matter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-color ink composition excellent in curing sensitivity and color reproducibility of an image obtained when curing. <P>SOLUTION: The ink composition comprises a coloring agent (A), a compound (B) represented by Formula (I), a polymerizable compound (C), and a polymerization initiator (D), and a content of the coloring agent (A) is 2 wt.% or less based on the total of the ink composition. In Formula (I), X is O, S, or, NR, n is 0 or 1, R is hydrogen atom, alkyl group, or, acyl group, R<SP>1</SP>-R<SP>8</SP>are each independently hydrogen atom or monovalent substituent, adjacent two groups among R<SP>1</SP>-R<SP>4</SP>may connect to each other to form a ring, and R<SP>5</SP>or R<SP>6</SP>and R<SP>7</SP>or R<SP>8</SP>may connect to each other to form an aliphatic ring except an aromatic ring. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an ink composition suitably used for inkjet recording, an ink set including the ink composition, an inkjet recording method using the ink composition, and a printed matter obtained using the ink composition. is there.

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

In addition, in the ink jet method, a method using dark color ink and light color ink is known as a method for improving gradation and graininess. For example, Patent Documents 1 and 2 describe a plurality of water-based dye inks having different dye concentrations.
Patent Document 3 discloses an ink jet ink set composed of at least dark color ink and light color ink that is cured by irradiating ultraviolet rays, and the ink constituting the ink jet ink set includes at least a colorant, a polymerizable compound, light Containing a polymerization initiator, the concentration ratio of the dark ink to the light ink is 2: 1 to 10: 1, and the concentration ratio of the photopolymerization initiator is 1: 1 to 3: An ink jet ink set characterized by 1 is described.

JP 60-56557 A JP-A-57-156264 JP 2004-359946 A

  An object of the present invention is a light-color ink composition having excellent curing sensitivity and excellent color reproducibility of an image obtained by curing, an ink set including the ink composition, and an ink jet recording method using the ink composition And providing a printed matter obtained using the ink composition.

The above object has been achieved by the means described in <1>, <8>, <9> and <10> below. It is shown below with <2>-<7> which are preferable embodiments.
<1> (A) a colorant, (B) a compound represented by formula (I), (C) a polymerizable compound, and (D) a polymerization initiator, and the content of the (A) colorant Is an ink composition characterized in that it is 2% by weight or less of the total ink composition,

（式（I）中、ＸはＯ、Ｓ、又は、ＮＲを表し、ｎは０又は１を表し、Ｒは水素原子、アルキル基、又は、アシル基を表し、Ｒ¹、Ｒ²、Ｒ³、Ｒ⁴、Ｒ⁵、Ｒ⁶、Ｒ⁷、及び、Ｒ⁸はそれぞれ独立に、水素原子、又は、一価の置換基を表し、Ｒ¹、Ｒ²、Ｒ³、及び、Ｒ⁴は、それぞれ隣接する２つが互いに連結して環を形成していてもよく、Ｒ⁵又はＲ⁶とＲ⁷又はＲ⁸とは互いに連結して脂肪族環を形成してもよいが、芳香族環を形成することはない。）
＜２＞ （Ｅ）分散剤をさらに含有する上記＜１＞に記載のインク組成物、
＜３＞ 前記（Ｃ）重合性化合物が、エチレン性不飽和化合物である上記＜１＞又は＜２＞に記載のインク組成物、
＜４＞ 前記（Ｃ）重合性化合物が、単官能重合性化合物及び二官能重合性化合物である上記＜１＞〜＜３＞のいずれか１つに記載のインク組成物、
＜５＞ 前記（Ｄ）重合開始剤が、α−アミノケトン類及びアシルフォスフィンオキサイド類よりなる群から選択される重合開始剤である上記＜１＞〜＜４＞のいずれか１つに記載のインク組成物、
＜６＞ 前記（Ａ）着色剤が、マゼンタ顔料又はシアン顔料である上記＜１＞〜＜５＞のいずれか１つに記載のインク組成物、
＜７＞ 前記（Ｂ）式（I）で表される化合物の含有量が、インク組成物全体に対し、０．０５〜３０重量％である上記＜１＞〜＜６＞のいずれか１つに記載のインク組成物、
＜８＞ 少なくとも１つの上記＜１＞〜＜７＞のいずれか１つに記載のインク組成物を含むインクセット、
＜９＞ （ａ¹）被記録媒体上に、上記＜１＞〜＜７＞のいずれか１つに記載のインク組成物を吐出する工程、及び、（ｂ¹）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する工程、を含むインクジェット記録方法、
＜１０＞ 上記＜９＞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。

(In the formula (I), X represents O, S, or NR, n represents 0 or 1, R represents a hydrogen atom, an alkyl group, or an acyl group, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ each independently represents a hydrogen atom or a monovalent substituent, and R ¹ , R ² , R ³ , and R ⁴ are Two adjacent to each other may be connected to each other to form a ring, and R ⁵ or R ⁶ and R ⁷ or R ⁸ may be connected to each other to form an aliphatic ring. It will not form.)
<2> (E) The ink composition according to <1>, further including a dispersant;
<3> The ink composition according to <1> or <2>, wherein the polymerizable compound (C) is an ethylenically unsaturated compound,
<4> The ink composition according to any one of <1> to <3>, wherein the polymerizable compound (C) is a monofunctional polymerizable compound or a bifunctional polymerizable compound;
<5> The polymerization initiator according to any one of <1> to <4>, wherein the (D) polymerization initiator is a polymerization initiator selected from the group consisting of α-aminoketones and acylphosphine oxides. An ink composition,
<6> The ink composition according to any one of <1> to <5>, wherein the (A) colorant is a magenta pigment or a cyan pigment.
<7> Any one of the above <1> to <6>, wherein the content of the compound represented by formula (I) is 0.05 to 30% by weight with respect to the whole ink composition. The ink composition according to claim 1,
<8> An ink set comprising at least one ink composition according to any one of the above items <1> to <7>.
<9> (a ¹ ) A step of discharging the ink composition according to any one of the above <1> to <7> on a recording medium, and (b ¹ ) the discharged ink composition Irradiating actinic radiation to cure the ink composition, an ink jet recording method,
<10> A printed matter recorded by the inkjet recording method according to <9>.

  According to the present invention, a light-color ink composition having excellent curing sensitivity and excellent color reproducibility of an image obtained by curing, an ink set including the ink composition, and an ink jet recording method using the ink composition And a printed matter obtained using the ink composition.

(1) Ink composition The ink composition of the present invention (hereinafter also simply referred to as “ink”) includes (A) a colorant, (B) a compound represented by formula (I), and (C) a polymerizable compound. And (D) a polymerization initiator is contained, and the content of the colorant (A) is 2% by weight or less of the whole ink composition.

（式（I）中、ＸはＯ、Ｓ、又は、ＮＲを表し、ｎは０又は１を表し、Ｒは水素原子、アルキル基、又は、アシル基を表し、Ｒ¹、Ｒ²、Ｒ³、Ｒ⁴、Ｒ⁵、Ｒ⁶、Ｒ⁷、及び、Ｒ⁸はそれぞれ独立に、水素原子、又は、一価の置換基を表し、Ｒ¹、Ｒ²、Ｒ³、及び、Ｒ⁴は、それぞれ隣接する２つが互いに連結して環を形成していてもよく、Ｒ⁵又はＲ⁶とＲ⁷又はＲ⁸とは互いに連結して脂肪族環を形成してもよいが、芳香族環を形成することはない。）

(In the formula (I), X represents O, S, or NR, n represents 0 or 1, R represents a hydrogen atom, an alkyl group, or an acyl group, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ each independently represents a hydrogen atom or a monovalent substituent, and R ¹ , R ² , R ³ , and R ⁴ are Two adjacent to each other may be connected to each other to form a ring, and R ⁵ or R ⁶ and R ⁷ or R ⁸ may be connected to each other to form an aliphatic ring. It will not form.)

The ink composition of the present invention is an ink composition having a colorant content of 2% by weight or less of the total ink composition and a low colorant content, and includes “light ink composition”, “light ink”, Also referred to as “light color ink composition” or “light color ink”.
Conventionally, it is known that a radiation curable ink-jet ink contains a sensitizer for so-called high sensitivity that promotes decomposition of a polymerization initiator by irradiation with actinic rays. However, in general, the sensitizer has a color such as yellow, and since it exists in the ink composition, it is difficult to reproduce the originally desired ink color without turbidity after inkjet recording. In particular, in the light color ink composition used in the ink set, since the amount of the colorant that can be contained is limited, the color reproducibility of the ink composition due to the sensitizer is remarkable. That is, a light-color ink composition that achieves both high sensitivity and color reproducibility has been desired.
Hereinafter, the present invention will be described in detail.

The ink composition of the present invention is an ink composition that can be cured by radiation, and is an oil-based ink composition.
The term “radiation” as used in the present invention is not particularly limited as long as it is an actinic radiation that can impart energy capable of generating a starting species in the ink composition by the irradiation. Among them, 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) Colorant The ink composition of the present invention contains (A) a colorant.
The content of the colorant in the ink composition of the present invention is 2% by weight or less, preferably 1.0% by weight or less, and preferably 0.8% by weight or less with respect to the entire ink composition. Is more preferable, 0.01 to 0.8% by weight is further preferable, and 0.2 to 0.7% by weight is particularly preferable.
Although there is no restriction | limiting in particular as a coloring agent which can be used for this invention, It can select and use arbitrarily from well-known coloring agents, such as a pigment and a soluble dye.
Among these, the ink composition of the present invention preferably contains a pigment, more preferably contains a magenta pigment, a cyan pigment or a black pigment, and further preferably contains a magenta pigment or a cyan pigment.
The pigment generally means a colorant that is sparingly soluble in various solvents (organic solvent, water). In a normal ink composition, the entire solid content of the colorant contained is dissolved in the ink composition. Means 10% by weight or less.
The colorant that can be suitably used in the ink composition of the present invention is a compound that does not function as a polymerization inhibitor in a polymerization reaction that is a curing reaction, from the viewpoint of not reducing the sensitivity of the curing reaction by actinic radiation. preferable.

Although it does not necessarily limit as a pigment which can be used for this invention, For example, the organic or inorganic pigment of the following number described in a color index can be used.
Examples of red or magenta pigments include Pigment Red 3, 5, 19, 22, 31, 38, 42, 43, 48: 1, 48: 2, 48: 3, 48: 4, 48: 5, 49: 1, and 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, and the like.
Examples of 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, and the like. Is mentioned.
Examples of the green pigment include Pigment Green 7, 26, 36, and 50.
As yellow pigments, Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, 120, 137, 138, 139, 153, 154, 155, 157, 166, 167, 168, 180, 185, 193 and the like.
Examples of the black pigment include Pigment Black 7, 28, 26, and the like.
Examples of white pigments include Pigment White 6, 18, 21 and the like.

Below, the oil-soluble dye which can be used by this invention is demonstrated.
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 weight 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. Therefore, the oil-soluble dye means a so-called water-insoluble pigment or oil-soluble dye, and among these, an oil-soluble dye is preferable.

  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 usable in the present invention, any magenta dye can be used. For example, aryl or heteryl 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, xanthene dyes; quinone dyes such as naphthoquinone, anthraquinone, anthrapyridone; condensed polycyclic dyes such as dioxazine dyes, etc. Can be mentioned.

  Among the oil-soluble dyes applicable to 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 a part of chromophore (chromogenic atomic group) is dissociated. In this case, the counter cation may be an alkali metal or ammonium. Such inorganic cations may be used, and organic cations such as pyridinium and quaternary ammonium salts may be used, and furthermore, polymer cations having such a partial structure may be used.

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; 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; C.I. 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 Spiron 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, the oil-soluble dye may be used alone or in combination of several kinds.

Moreover, when using an oil-soluble dye as a colorant, other water-soluble dyes, disperse dyes, pigments, and other colorants can be used in combination as long as the effects of the present invention are not impaired.
In the present invention, a disperse dye can be used as long as it is soluble in a water-immiscible organic solvent. The disperse dye generally includes a water-soluble dye, but in the present invention, the disperse dye is preferably used as long as it is soluble in a water-immiscible organic solvent. Preferable specific examples of the disperse dye 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; C.I. 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;

  It is preferable that the colorant that can be used in the present invention is appropriately dispersed in the ink after being added to the ink composition of the present invention or the ink composition for inkjet recording. 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.

The colorant may be added by directly adding it together with each component in the preparation of the ink composition of the present invention. However, in order to improve dispersibility, the colorant is previously added to a dispersion medium such as a solvent or a radical polymerizable compound used in the present invention. It can also be added after being uniformly dispersed or dissolved.
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 a radical polymerizable compound. It is preferable to add and mix in advance in such a dispersion medium. In consideration of only dispersibility, it is preferable to select a monomer having the lowest viscosity as the polymerizable compound used for the addition of the colorant. These colorants may be used by appropriately selecting one type or two or more types according to the purpose of use of the ink composition.

  In addition, when using a colorant such as a pigment that remains solid in the ink composition of the present invention, the average particle diameter of the colorant particles is preferably 0.005 to 0.5 μm, more preferably 0. It is preferable to set the colorant, the dispersant, the dispersion medium, the dispersion conditions, and the filtration conditions so that the thickness is 0.01 to 0.45 μm, more preferably 0.015 to 0.4 μm. 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.

(B) Compound Represented by Formula (I) The ink composition of the present invention contains (B) a compound represented by formula (I) as a sensitizer.

In the formula (I), X represents O, S or NR. R represents a hydrogen atom, an alkyl group or an acyl group, and is preferably an alkyl group or an acyl group.
In the formula (I), n represents 0 or 1.
X is preferably O or S, and more preferably S.
In addition, when n is 0, there is no carbon atom bonded to R ⁷ and R ^8, and X containing a hetero atom and a carbon atom bonded to R ⁵ and R ⁶ are directly bonded to form X. A 5-membered heterocycle containing it.

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ each independently represents a hydrogen atom or a monovalent substituent.
As monovalent substituents for R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ , halogen atoms, aliphatic groups, aromatic groups, heterocyclic groups, cyano groups, 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, sulfonamide 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 And so on. Among these, an alkyl group or a halogen atom is preferable.

Wherein the alkyl groups which may R ¹ in ^{(I), R 2, R} 3, R 4, R 5, R 6, R 7 and R ⁸ represents a monovalent substituent, 1 to 10 carbon atoms Alkyl groups are preferable, and those having 1 to 4 carbon atoms such as methyl group, ethyl group, propyl group, n-butyl group, sec-butyl group and t-butyl group are more preferable.
Similarly, alkoxy groups include those having 1 to 4 carbon atoms such as methoxy, ethoxy, hydroxyethoxy, propoxy, n-butoxy, isobutoxy, sec-butoxy, and t-butoxy. Preferably mentioned.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

R ^1, R ^2, R ³ and R ^4, two respectively adjacent but connected to each other, for example, condensation may form a ring.
Examples of the ring structure in the case where these form a ring include a 5- or 6-membered aliphatic ring and an aromatic ring, and may be a heterocyclic ring containing an element other than a carbon atom. The rings may be further combined to form a binuclear ring, for example, a condensed ring. Further, these ring structures may further have a substituent exemplified when R ^{1 to} R ⁸ represent a monovalent substituent in the formula (I). Examples of heteroatoms when the formed ring structure is a heterocycle include N, O and S.

When n = 1, R ⁵ or R ⁶ and R ⁷ or R ⁸ may be connected to each other to form an aliphatic ring, but do not form an aromatic ring. The aliphatic ring is preferably a 3- to 6-membered ring, and more preferably a 5- or 6-membered ring.

  The compound represented by the formula (I) is preferably a compound represented by the following formula (I-A).

In the formula (IA), X represents O or S, n represents 0 or 1, and R ^1A , R ^2A , R ^3A , R ^4A , R ^5A , R ^6A , R ^7A and R ^8A are each independently Represents a hydrogen atom, an alkyl group, a halogen atom, a hydroxyl group, a cyano group, a nitro group, an amino group, an alkylthio group, an alkylamino group, an alkoxy group, an alkoxycarbonyl group, an acyloxy group, an acyl group, a carboxyl group or a sulfo group. Two adjacent R ^1A , R ^2A , R ^3A and R ^4A may be linked (condensed) with each other to form a ring. R ^5A or R ^6A and R ^7A or R ^8A may ^combine with each other to form an aliphatic ring, but do not form an aromatic ring.
Further, these ring structures are the examples shown in the formula (I) when R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ represent a monovalent substituent. It may further have a substituent. When the ring structure is a heterocyclic ring, examples of heteroatoms include N, O, and S.

  The compound represented by the formula (I) is more preferably a compound represented by the following formula (I-B).

In the formula (IB), X represents O or ^{S, R 1B, R 2B,} R 3B, R 4B, R 5B, R 6B, respectively the R ^7B and R ^8B independently, a hydrogen atom, an alkyl group, a halogen Atom, hydroxyl group, cyano group, nitro group, amino group, alkylthio group, alkylamino group, alkoxy group, alkoxycarbonyl group, acyloxy group, acyl group, carboxyl group or sulfo group are represented. R ^1B , R ^2B , R ^3B and R ^4B may be linked (condensed) with each other adjacent two to form a ring. R ^5B or R ^6B and R ^7B or R ^8B may ^combine with each other to form an aliphatic ring, but do not form an aromatic ring.
Further, these ring structures are the examples shown in the formula (I) when R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ represent a monovalent substituent. It may further have a substituent. When the ring structure is a heterocyclic ring, examples of heteroatoms include N, O, and S.

  Furthermore, the compound represented by the formula (I) is more preferably a compound represented by the following formula (I-C).

In the formula (IC), R ^1C , R ^2C , R ^3C , R ^4C , R ^5C , R ^6C , R ^7C and R ^8C are each independently a hydrogen atom, alkyl group, halogen atom, hydroxyl group, cyano group, nitro group Represents a group, an amino group, an alkylthio group, an alkylamino group, an alkoxy group, an alkoxycarbonyl group, an acyloxy group, an acyl group, a carboxyl group or a sulfo group.
R ^1C , R ^2C , R ^3C and R ^4C may be formed by condensing two adjacent groups to form a 5- or 6-membered aliphatic ring or aromatic ring. Heterocycles containing other elements may be used, and the formed rings may be further combined to form a binuclear ring, for example, a condensed ring. R ^5C or R ^6C and R ^7C or R ^8C may ^combine with each other to form an aliphatic ring, but do not form an aromatic ring.
Further, these ring structures are the examples shown in the formula (I) when R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ represent a monovalent substituent. It may further have a substituent. When the ring structure is a heterocyclic ring, examples of heteroatoms include N, O, and S.

Further, at least one of R ^1C , R ^2C , R ^3C , R ^4C , R ^5C , R ^6C , R ^7C and R ^8C is preferably a halogen atom. Preferred substitution positions include R ^1C , R ^2C , R ^3C and R ^4C , with R ^2C being most preferred. The number of halogen atoms in R ^{1C to} R ^8C is preferably 1 or 2, and more preferably 1.

R ^2C is preferably a substituent other than hydrogen. Among them, an alkyl group, a halogen atom, an acyloxy group, or an alkoxycarbonyl group is preferable because of good matching with a light source and high sensitivity. More preferred.

Either R ^7C or R ^8C is preferably a substituent other than hydrogen, and more preferably both are substituents other than hydrogen. Preferable substituents include an alkyl group, a halogen atom, a carboxyl group, and an alkoxycarbonyl group. Among them, an alkyl group and an alkoxycarbonyl group are preferable, and an alkyl group is most preferable.
Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and a chlorine atom, a bromine atom and an iodine atom are preferable.

  The alkyl group is preferably an alkyl group having 1 to 10 carbon atoms, and has 1 to 4 carbon atoms such as a methyl group, an ethyl group, a propyl group, an n-butyl group, a sec-butyl group, or a t-butyl group. Are more preferred.

The acyloxy group is preferably an aliphatic acyloxy group having 2 to 10 carbon atoms, and more preferably an aliphatic acyloxy group having 2 to 5 carbon atoms.
As the alkoxycarbonyl group, an aliphatic alkoxycarbonyl group having 2 to 10 carbon atoms is preferable, and an alkoxycarbonyl group having 2 to 5 carbon atoms is more preferable.

Specific examples of the compound represented by formula (I) that can be suitably used in the present invention [Exemplary compounds (I-1) to (I-133)] are shown below, but the present invention is limited to these. It is not a thing. In some of the chemical formulas in the present invention, the hydrocarbon chain may be described by a simplified structural formula in which symbols of carbon (C) and hydrogen (H) are omitted. Further, in the following specific examples, Me represents a methyl group, Bu ^t represents a t- butyl group, Pr ⁱ represents an isopropyl group.

  Among these, the exemplified compound (I-4), (I-14), (I-17), (I-71), (I-116) or (I-129) is preferable, and the exemplified compound (I-14 Is particularly preferred.

  Examples of the method for synthesizing the compound represented by formula (I) include, for example, JP-A No. 2004-189695, Tetrahedron, Vol. 49, p939 (1993), Journal of Organic Chemistry, p893 (1945), and It can be synthesized by a known method described in Journal of Organic Chemistry, p4939 (1965).

The content of the compound represented by the formula (I) in the ink composition of the present invention is preferably 0.05 to 30% by weight, and preferably 0.1 to 20% by weight with respect to the total amount of the ink composition. Is more preferable, and it is further more preferable that it is 0.2 to 10 weight%.
The content in the ink composition of the present invention will be described in relation to (D) the polymerization initiator described later. By weight ratio, (D) the polymerization initiator: (B) the compound represented by the formula (I) = 200: 1 to 1: 200 is preferable, 50: 1 to 1:50 is more preferable, and 20: 1 to 1: 5 is more preferable.

[Other sensitizers]
In the present invention, in addition to the compound represented by the formula (I), a known sensitizer can be used in combination as long as the effects of the present invention are not impaired. It is preferable not to contain this sensitizer.
When the ink composition of the present invention contains other sensitizers, the content thereof is, by weight ratio, the compound represented by formula (I) with respect to the compound represented by formula (I): other The sensitizer is preferably 1: 5 to 100: 1, more preferably 1: 1 to 100: 1, and further preferably 2: 1 to 100: 1.
Examples of other sensitizers that can be used in combination include benzophenone, thioxanthone, isopropylthioxanthone, anthraquinone, 3-acylcoumarin derivatives, terphenyl, styryl ketone, 3- (aroylmethylene) thiazoline, camphorquinone, eosin, rhodamine, Examples include erythrosine and α- (p-dimethylaminobenzylidene) ketone.

Further examples of other sensitizers that can be used in combination are shown below.
(1) Thioxanthone Thioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-dodecylthioxanthone, 2,4-di-ethylthioxanthone, 2,4-dimethylthioxanthone, 1-methoxycarbonylthioxanthone, 2-ethoxycarbonylthioxanthone, 3 -(2-methoxyethoxycarbonyl) thioxanthone, 4-butoxycarbonylthioxanthone, 3-butoxycarbonyl-7-methylthioxanthone, 1-cyano-3-chlorothioxanthone, 1-ethoxycarbonyl-3-chlorothioxanthone, 1-ethoxycarbonyl- 3-ethoxythioxanthone, 1-ethoxycarbonyl-3-aminothioxanthone, 1-ethoxycarbonyl-3-phenylsulfurylthioxanthone, 3,4- Di [2- (2-methoxyethoxy) ethoxycarbonyl] thioxanthone, 1-ethoxycarbonyl-3- (1-methyl-1-morpholinoethyl) thioxanthone, 2-methyl-6-dimethoxymethylthioxanthone, 2-methyl-6- (1,1-dimethoxybenzyl) thioxanthone, 2-morpholinomethylthioxanthone, 2-methyl-6-morpholinomethylthioxanthone, n-allylthioxanthone-3,4-dicarboximide, n-octylthioxanthone-3,4-dicarboxy Imido, N- (1,1,3,3-tetramethylbutyl) thioxanthone-3,4-dicarboximide, 1-phenoxythioxanthone, 6-ethoxycarbonyl-2-methoxythioxanthone, 6-ethoxycarbonyl-2-methyl Thioxanthone Thioxanthone-2-polyethylene glycol ester, 2-hydroxy-3- (3,4-dimethyl-9-oxo -9H- thioxanthone-2-yloxy) -N, N, N-trimethyl-1-propanaminium chloride;

(2) Benzophenone Benzophenone, 4-phenylbenzophenone, 4-methoxybenzophenone, 4,4′-dimethoxybenzophenone, 4,4′-dimethylbenzophenone, 4,4′-dichlorobenzophenone, 4,4′-dimethylaminobenzophenone, 4 , 4'-diethylaminobenzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, 4- (4-methylthiophenyl) benzophenone, 3,3'-dimethyl-4-methoxybenzophenone, methyl-2-benzoylbenzoate 4- (2-hydroxyethylthio) benzophenone, 4- (4-tolylthio) benzophenone, 4-benzoyl-N, N, N-trimethylbenzenemethanaminium chloride, 2-hydroxy-3- (4-benzoylphenoxy) ) -N, N, N-trimethyl-1-propanaminium chloride monohydrate, 4- (13-acryloyl-1,4,7,10,13-pentaoxatridecyl) benzophenone, 4-benzoyl-N , N-dimethyl-N- [2- (1-oxo-2-propenyl) oxy] ethylbenzenemethanaminium chloride;

(3) 3-acylcoumarin 3-benzoylcoumarin, 3-benzoyl-7-methoxycoumarin, 3-benzoyl-5,7-dipropoxycoumarin, 3-benzoyl-6,8-dichlorocoumarin, 3-benzoyl-6 Chlorocoumarin, 3,3′-carbonylbis [5,7-di (propoxy) coumarin], 3,3′-carbonylbis (7-methoxycoumarin), 3,3′-carbonylbis (7-diethylaminocoumarin), 3-isobutyroylcoumarin, 3-benzoyl-5,7-dimethoxycoumarin, 3-benzoyl-5,7-diethoxycoumarin, 3-benzoyl-5,7-dibutoxycoumarin, 3-benzoyl-5,7- Di (methoxyethoxy) coumarin, 3-benzoyl-5,7-di (allyloxy) coumarin, 3-benzoyl-7-dimethyl Tylaminocoumarin, 3-benzoyl-7-diethylaminocoumarin, 3-isobutyroyl-7-dimethylaminocoumarin, 5,7-dimethoxy-3- (1-naphthoyl) coumarin, 5,7-dimethoxy-3- (1-naphthoyl) ) Coumarin, 3-benzoylbenzo [f] coumarin, 7-diethylamino-3-thienoylcoumarin, 3- (4-cyanobenzoyl) -5,7-dimethoxycoumarin;

(4) 3- (Aroylmethylene) thiazoline 3-methyl-2-benzoylmethylene-β-naphthothiazoline, 3-methyl-2-benzoylmethylenebenzothiazoline, 3-ethyl-2-propionylmethylene-β-naphthothiazoline;

(5) Anthracene 9,10-dimethoxyanthracene, 9,10-diethoxyanthracene, 9,10-dimethoxy-2-ethylanthracene,

(6) Other carbonyl compounds Acetophenone, 3-methoxyacetophenone, 4-phenylacetophenone, benzyl, 2-acetylnaphthalene, 2-naphthaldehyde, 9,10-naphtholaquinone, 9-fluorenone, dibenzosuberone, xanthone, 2,5 -Bis (4-diethylaminobenzylidene) cyclopentanone, 2- (4-dimethylaminobenzylidene) indan-1-one, 3- (4-dimethylaminophenyl) -1-indan-5-ylpropenone, 3-phenylthiophthalimide N-methyl-3,5-di (ethylthio) phthalimide.

(C) Polymerizable compound The ink composition of the present invention contains (C) a polymerizable compound.
The polymerizable compound that can be used in the present invention is preferably an addition polymerizable compound, more preferably a radical polymerizable compound or a cationic polymerizable compound, still more preferably a radical polymerizable compound, and ethylene. It is particularly preferable that the compound be an unsaturated compound.
Moreover, the polymeric compound which can be used for this invention may be used individually by 1 type, or may use 2 or more types, for example, may use together a radically polymerizable compound and a cationically polymerizable compound. Good.

  The content of the polymerizable compound in the ink composition of the present invention is preferably 60 to 95 parts by weight, more preferably 65 to 90 parts by weight, and 70 to 90 parts by weight with respect to the total amount of the ink composition. More preferably, it is a part. Within the above range, the curability is excellent and the viscosity is moderate.

  Of the polymerizable compounds in the ink composition of the present invention, at least one is preferably a monofunctional polymerizable compound, more preferably at least one is a monofunctional ethylenically unsaturated compound, and at least one Is more preferably a monofunctional acrylate compound. When a monofunctional polymerizable compound is used for the ink composition, in addition to sufficient curability, sufficient flexibility of a film obtained by curing the ink composition can be obtained.

  The ink composition of the present invention preferably contains a monofunctional polymerizable compound and a bifunctional polymerizable compound, and the polymerizable compound contained in the ink composition of the present invention is a monofunctional polymerizable compound and a bifunctional polymerization. It is more preferable that it is only an ionic compound.

  When a monofunctional polymerizable compound is used as the polymerizable compound, the proportion of the monofunctional polymerizable compound in the ink composition is preferably 30 to 80% by weight, and more preferably 40 to 70% by weight. More preferably, it is 50 to 60% by weight. It is excellent in the adhesiveness to a base material as it is the said range, and the stickiness of the image surface after hardening can be suppressed.

  When having a bifunctional polymerizable compound as the polymerizable compound, the proportion of the bifunctional polymerizable compound in the ink composition is preferably 15 to 45% by weight, more preferably 20 to 40% by weight. Preferably, it is 25 to 35% by weight. Within the above range, the curability is excellent, the strength of the cured film is sufficient, and the occurrence of cracks and the like can be reduced.

(Radically polymerizable compound)
In the present invention, it is preferable to use a compound having an ethylenically unsaturated bond as the radical polymerizable compound. Specific examples include (meth) acrylic acid, (meth) acrylic acid esters, (meth) acrylamide compounds, and vinyl compounds (for example, aliphatic vinyl compounds, aromatic vinyl compounds, and N-vinyl compounds).

  In addition, polymerizable oligomers can be blended in the same manner as the monomer. Examples of the polymerizable oligomer include epoxy acrylate, aliphatic urethane acrylate, aromatic urethane acrylate, polyester acrylate, and linear acrylic oligomer.

In the ink composition of the present invention, it is preferable to use a radical polymerizable monomer having a cyclic structure as the monofunctional polymerizable compound, and to use an N-vinyl compound and / or an aromatic monofunctional radical polymerizable monomer. It is more preferable to use an N-vinyl compound and an aromatic monofunctional radical polymerizable monomer.
In the ink composition of the present invention, it is preferable to use a polyfunctional aliphatic (meth) acrylate compound and / or a polyfunctional vinyl ether compound as the polyfunctional polymerizable compound, and a bifunctional aliphatic (meth) acrylate compound and More preferably, a bifunctional vinyl ether compound is used, more preferably a bifunctional aliphatic (meth) acrylate compound and a bifunctional vinyl ether compound are used, and an aliphatic di (meth) acrylate compound and a divinyl ether compound are used. It is particularly preferable to do this.

<(Meth) acrylate compound>
As the compound having an ethylenically unsaturated bond, various (meth) acrylate compounds can be preferably used.
For example, isoamyl acrylate, stearyl acrylate, lauryl acrylate, octyl acrylate, decyl acrylate, isoamyl stil acrylate, isostearyl acrylate, 2-ethylhexyl diglycol acrylate, 2-hydroxybutyl acrylate, 2-acryloyloxyethyl hexahydrophthalic acid, butoxy Ethyl acrylate, ethoxydiethylene glycol acrylate, methoxydiethylene glycol acrylate, methoxypolyethylene glycol acrylate, methoxypropylene glycol acrylate, phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, isobornyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2 Hydroxy-3-phenoxypropyl acrylate, 2-acryloxyethyl succinic acid, 2-acryloxyethyl phthalic acid, 2-acryloxyethyl-2-hydroxyethyl phthalic acid, lactone-modified flexible acrylate, t-butyl And monofunctional (meth) acrylate compounds such as cyclohexyl acrylate.

  Also, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, polypropylene glycol diacrylate, 1,4-butanediol diacrylate, 1,6-hexane Diol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, dimethylol-tricyclodecane diacrylate, EO (ethylene oxide) adduct of bisphenol A, PO (propylene oxide) adduct of bisphenol A Diacrylate, hydroxypivalic acid neopentyl glycol diacrylate, polytetramethylene glycol diacrylate Rate, trimethylolpropane triacrylate, EO modified trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, ditrimethylolpropane tetraacrylate, glycerin propoxytriacrylate, caprolactone modified trimethylolpropane triacrylate And polyfunctional (meth) acrylate compounds such as pentaerythritol ethoxytetraacrylate, caprolactone-modified dipentaerythritol hexaacrylate, and PO-modified neopentyl glycol diacrylate.

  The ink composition of the present invention preferably contains a polyfunctional (meth) acrylate compound, more preferably contains a di (meth) acrylate compound, and contains PO-modified neopentyl glycol diacrylate. More preferably.

<N-vinyl compound>
In the present invention, it is preferable to use a polymerizable compound (N-vinyl compound) having an N-vinyl group and a group having a cyclic structure. Among these, N-vinylcarbazole, 1-vinylimidazole, and N-vinyl lactams are preferably used, and N-vinyl lactams are more preferably used.
Preferable examples of N-vinyl lactams that can be used in the present invention include compounds represented by the following formula (N).

  In the formula (N), m represents an integer of 1 to 5, and m is 2 to 4 from the viewpoint of flexibility after the ink composition is cured, adhesion to the support, and availability of raw materials. It is preferably an integer, more preferably m is 2 or 4, and particularly preferably m is 4, that is, N-vinylcaprolactam. N-vinylcaprolactam is preferable because it is excellent in safety, is generally available and can be obtained at a relatively low price, and provides particularly good ink curability and adhesion of a cured film to a support.

The N-vinyl lactams may have a substituent such as an alkyl group or an aryl group on the lactam ring, and may be linked with a saturated or unsaturated ring structure.
The N-vinyl lactams may be contained in the ink composition alone or in a plurality of kinds.

  In the present invention, the N-vinyl compound is preferably contained in an amount of 5 to 40% by weight, more preferably 10 to 30% by weight, and more preferably 12 to 20% by weight based on the total ink composition. More preferably. In the above range, an ink composition exhibiting good copolymerizability with the polypolymerizable compound and excellent in curability and blocking resistance can be obtained.

The ink composition of the present invention preferably contains 10% by weight or more of the N-vinyl lactam represented by the formula (N), more preferably 10 to 40% by weight of the total ink composition. It is more preferable to contain 30% by weight to 30% by weight, and it is particularly preferable to contain 12% to 20% by weight.
When the amount of N-vinyl lactam used is within the above range, the curability, the flexibility of the cured film, and the adhesion of the cured film to the support are excellent. N-vinyl lactams are compounds having a relatively high melting point. When the content of N-vinyl lactam is 40% by weight or less, good solubility is exhibited even at a low temperature of 0 ° C. or lower, and the temperature range in which the ink composition can be handled is widened.

<Vinyl ether compound>
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 vinyl ether, 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 monofunctional vinyl ethers include, for example, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, n-butyl vinyl ether, t-butyl vinyl ether, 2-ethylhexyl vinyl ether, n-nonyl vinyl ether, lauryl vinyl ether, cyclohexyl vinyl ether, cyclohexyl methyl vinyl ether, 4 -Methylcyclohexyl methyl vinyl ether, benzyl vinyl ether, dicyclopentenyl vinyl ether, 2-dicyclopentenoxyethyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, butoxyethyl vinyl ether, methoxyethoxyethyl vinyl ether, ethoxyethoxyethyl vinyl ether, methoxypolyethylene glycol vinyl D Ter, tetrahydrofurfuryl vinyl ether, 2-hydroxyethyl vinyl ether, 2-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, 4-hydroxymethylcyclohexyl methyl vinyl ether, diethylene glycol monovinyl ether, polyethylene glycol vinyl ether, chloroethyl vinyl ether, chlorobutyl vinyl ether, chloro Examples thereof include ethoxyethyl vinyl ether, phenylethyl vinyl ether, phenoxy polyethylene glycol vinyl ether and the like.

  Examples of the polyfunctional vinyl ether include, for example, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, polyethylene glycol divinyl ether, propylene glycol divinyl ether, butylene glycol divinyl ether, hexanediol divinyl ether, and bisphenol A alkylene. Divinyl ethers such as oxide divinyl ether and bisphenol F alkylene oxide divinyl ether; trimethylol ethane trivinyl ether, trimethylol propane trivinyl ether, ditrimethylol propane tetravinyl ether, glycerin trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol pen Tavinyl ether, dipentaerythritol hexavinyl ether, ethylene oxide-added trimethylolpropane trivinyl ether, propylene oxide-added trimethylolpropane trivinyl ether, ethylene oxide-added ditrimethylolpropane tetravinyl ether, propylene oxide-added ditrimethylolpropane tetravinyl ether, ethylene oxide-added pentaerythritol And polyfunctional vinyl ethers such as tetravinyl ether, propylene oxide-added pentaerythritol tetravinyl ether, ethylene oxide-added dipentaerythritol hexavinyl ether, and propylene oxide-added dipentaerythritol hexavinyl ether.

  The ink composition of the present invention preferably contains a polyfunctional vinyl ether compound, and more preferably contains a bifunctional vinyl ether compound.

<Radically polymerizable monomer having a cyclic structure>
The monofunctional radical polymerizable monomer having a cyclic structure is preferably a monofunctional radical polymerizable monomer represented by the following formula (A1). The aromatic monofunctional radical polymerizable monomer is a monofunctional radical polymerizable monomer having an aromatic group, and the monofunctional radical polymerizable monomer having an aliphatic cyclic structure is an alicyclic ring that may contain a hetero atom. It is a monofunctional radically polymerizable monomer having a formula hydrocarbon group. The monofunctional radically polymerizable monomer is a compound having only one polymerizable ethylenically unsaturated bond. Examples of the group having a polymerizable ethylenically unsaturated bond include acryloyloxy group and methacryloyloxy group. Preferred examples include acrylamide group, methacrylamide group, vinyl group and vinyloxy group.

In the above formula (A1), R ¹ represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms, and X ¹ represents a single bond, an ether bond (—O—), an ester bond (—C ( O) O- or -OC (O)-), amide bond (-C (O) NH- or -NHC (O)-), carbonyl bond (-C (O)-), branched An alkylene group having 20 or less carbon atoms, or a second divalent linking group in combination of these may be bonded, and only the first divalent linking group or the second divalent linking group may be bonded. When it has, what has an ether bond, an ester bond, and a C20 or less alkylene group is preferable.
R ² is an aromatic group or alicyclic hydrocarbon group containing a monocyclic aromatic group and a polycyclic aromatic group, and the aromatic group and alicyclic hydrocarbon group are a halogen atom, a hydroxyl group, an amino group , A siloxane group, and a substituent having 30 or less carbon atoms, and the aromatic structure or alicyclic hydrocarbon group may contain a heteroatom such as O, N, or S. .

In the above formula (A1), R ¹ is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or a methyl group, and particularly preferably a hydrogen atom.
X ¹ preferably has an ester bond (—C (O) O—).
That is, in the present invention, the monofunctional radical polymerizable monomer having an aliphatic cyclic structure and the aromatic monofunctional radical polymerizable monomer are preferably acrylate (acrylic acid ester) or methacrylate (methacrylic acid ester).

(Aromatic monofunctional radical polymerizable monomer)
The aromatic monofunctional radically polymerizable monomer is preferably a polymerizable monomer represented by the following formula (A5).

（式（Ａ５）中、Ｒ¹は水素原子、ハロゲン原子、又は、炭素数１〜４のアルキル基を表し、Ｘ¹は二価の連結基を表し、Ｒ⁶は置換基を表し、ｕは０〜５の整数を表し、また、ｕ個存在するＲ⁵はそれぞれ同じであっても、異なっていてもよく、複数のＲ⁵がお互いに結合して環を形成してもよく、その環は芳香環であってもよい。）

(In formula (A5), R ¹ represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms, X ¹ represents a divalent linking group, R ⁶ represents a substituent, and u represents Represents an integer of 0 to 5, and u R ⁵ may be the same or different, and a plurality of R ⁵ may be bonded to each other to form a ring. May be an aromatic ring.)

In formula (A5), R ¹ is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or a methyl group, and still more preferably a hydrogen atom.
X ¹ has the same meaning as X ¹ in Formula (A2), and a preferred range is also the same.
R ⁵ present in u may each independently be a monovalent or polyvalent substituent, and as a monovalent substituent, a hydrogen atom, a hydroxyl group, a substituted or unsubstituted amino group, a thiol group, a siloxane group Or, it is preferably a hydrocarbon group or heterocyclic group having a total carbon number of 30 or less which may further have a substituent.

In the formula (A5), when a plurality of R ⁵ are bonded to each other to form a ring, it is preferable that an aromatic ring is formed.
That is, in the formula (A5), preferred as the aromatic group is a group obtained by removing one or more hydrogen from monocyclic aromatic benzene (phenyl group, phenylene group, etc.), as well as 2 to 4 rings. It is the polycyclic aromatic group which has, and is not limited. Specifically, naphthalene, anthracene, 1H-indene, 9H-fluorene, 1H-phenalene, phenanthrene, triphenylene, pyrene, naphthacene, tetraphenylene, biphenylene, as-indacene, s-indacene, acenaphthylene, fluoranthene, acephenanthrylene , Groups obtained by removing one or more hydrogen atoms from, for example, aceanthrylene, chrysene, preyandene and the like.

  These aromatic groups may be aromatic heterocyclic groups containing heteroatoms such as O, N, and S. Specifically, furan, thiophene, 1H-pyrrole, 2H-pyrrole, 1H-pyrazole, 1H-imidazole, isoxazole, isothiazole, 2H-pyran, 2H-thiopyran, pyridine, pyridazine, pyrimidine, pyrazine, 1,2 Group obtained by removing at least one hydrogen atom from a monocyclic aromatic heterocyclic compound such as 1,3-triazole or 1,2,4-triazole.

  Thianthrene, isobenzofuran, isochromene, 4H-chromene, xanthene, phenoxathiin, indolizine, isoindole, indole, indazole, purine, 4H-quinolidine, isoquinoline, quinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine , Carbazole, β-carboline, phenanthridine, acridine, perimidine, phenanthroline, phenazine, phenothiazine, phenoxazine, pyrrolidine and the like, a group obtained by removing at least one hydrogen atom.

  The aromatic group may have one or more halogen atoms, hydroxyl groups, amino groups, thiol groups, siloxane groups, and substituents having 30 or less carbon atoms. For example, you may form the cyclic structure containing hetero atoms, such as O, N, and S, by two or more substituents which an aromatic group has like phthalic anhydride and phthalimide anhydride.

  In the present invention, the polycyclic aromatic group is more preferably a polycyclic aromatic group having 2 to 3 rings, and particularly preferably a naphthyl group.

  Specific examples of the aromatic radical polymerizable monomer include [L-1] to [L-71], but are not limited to the following. Among these, an aromatic monofunctional radical polymerizable monomer is preferable.

[Monofunctional radically polymerizable monomer having an aliphatic cyclic structure]
R ^{2 in the} formula (A1) may be an alicyclic hydrocarbon group. Moreover, the group which has an alicyclic hydrocarbon group containing hetero atoms, such as O, N, and S, may be sufficient.
The alicyclic hydrocarbon group may be a group having a cycloalkane having 3 to 12 carbon atoms.
Specific examples of the alicyclic hydrocarbon group containing a heteroatom such as O, N, and S include pyrrolidine, pyrazolidine, imidazolidine, isoxazolidine, isothiazolidine, piperidine, piperazine, morpholine, thiomorpholine, and diazole. And a group in which one or more hydrogen atoms are removed from triazole or tetrazole.
These alicyclic hydrocarbon groups and alicyclic hydrocarbon groups having a heterocycle may have a substituent, such as a halogen atom, hydroxyl group, amino group, thiol group, siloxane Group, a hydrocarbon group having a total carbon number of 30 or less which may have a substituent or a heterocyclic group containing a heteroatom such as O, N, S or the like, or an oxy group (= O as a divalent substituent) ) Is preferable.
The radical polymerizable monomer having an aliphatic cyclic structure has a radical polymerizable group in addition to the aliphatic cyclic structure, and the ethylenically unsaturated bond in the aliphatic cyclic structure is a polymerizable ethylene. Not applicable to sex unsaturated bond.

  As the monofunctional radically polymerizable monomer having an aliphatic cyclic structure, a compound having an alicyclic skeleton represented by the following formula (A2) may be used.

In Formula (A2), R ¹ represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms, X ¹ represents a divalent linking group, an ether group (—O—), an ester group ( -C (O) O- or -OC (O)-), amide group (-C (O) NR'-), carbonyl group (-C (O)-), nitrogen atom (-NR'-), substitution It is preferable that it is a C1-C15 alkylene group which may have group, or a bivalent group which combined these 2 or more. R ′ represents a hydrogen atom, a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms. R ² represents a substituent, r represents an integer of 0 to 5, q represents a cyclic hydrocarbon structure, and the cyclic hydrocarbon structure includes a carbonyl bond (—C (O) —) and / or a hydrocarbon bond in addition to the hydrocarbon bond. Alternatively, an ester bond (—C (O) O—) may be contained, and r ² R ^{2 s} may be the same or different from each other, and one carbon atom in the norbornene skeleton is substituted with an ether. A bond (—O—) and / or an ester bond (—C (O) O—) may be substituted.
In formula (A2), R ¹ is preferably a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, more preferably a hydrogen atom or a methyl group.

The end bonded to the vinyl group of X ¹ in Formula (A2) is preferably an ester group or an amide group in which the carbonyl carbon of X ¹ and the vinyl group are bonded, and more preferably an ester bond. In particular, it is preferable to have a structure of H ₂ C═C (R ¹ ) —C (O) O—. In that case, the other part of X ¹ bonded to the norbornene skeleton may be a single bond or may be arbitrarily selected from the above groups.
The vinyl moiety containing R ¹ and X ¹ (H ₂ C═C (R ¹ ) —X ¹ —) can be attached at any position on the alicyclic hydrocarbon structure. In addition, "on each alicyclic hydrocarbon structure" refers to the norbornene structure and the cyclic hydrocarbon structure containing q in the formula (A2).
Further, from the viewpoint of improving the affinity with the colorant, the end bonded to the alicyclic hydrocarbon structure of X ¹ in Formula (A2) is preferably an oxygen atom, and is an etheric oxygen atom. More preferably, X ¹ in formula (A2) is more preferably —C (O) O (CH ₂ CH ₂ O) _p — (p represents 1 or 2).

R ² in formula (A2) independently represents a substituent, and can be bonded at any position on the alicyclic hydrocarbon structure. Also, r R ^{2 s} may be the same or different.
The r ² R ^{2 s} may be each independently a monovalent or polyvalent substituent, and as a monovalent substituent, a hydrogen atom, a hydroxyl group, a substituted or unsubstituted amino group, a thiol group, a siloxane group Furthermore, it is preferably a hydrocarbon group or heterocyclic group having a total carbon number of 30 or less which may have a substituent, or an oxy group (═O) as a divalent substituent.
The substitution number r of R ² represents an integer of 0 to 5.

  Q in the formula (A2) represents a cyclic hydrocarbon structure, and both ends thereof may be substituted at any position of the norbornene skeleton, and may be a monocyclic structure or a polycyclic structure; In addition to the hydrocarbon bond, the cyclic hydrocarbon structure may contain a carbonyl bond (—C (O) —) and / or an ester bond (—C (O) O—).

  The monomer represented by the formula (A2) is preferably a monomer represented by the formula (A3) or the formula (A4). Note that the unsaturated bond in the cyclic hydrocarbon structure in the formula (A4) has low radical polymerizability, and in the present invention, the compound represented by the formula (A4) is a monofunctional radical polymerizable monomer.

In formula (A3) and formula (A4), R ¹ represents a hydrogen atom, a halogen atom, or an alkyl group having 1 to 4 carbon atoms, X ¹ represents a divalent linking group, and R ³ and R ⁴ represent Each independently represents a substituent, s and t each independently represent an integer of 0 to 5, and s R ³ and t R ⁴ may be the same or different. Good.

R ¹ and X ¹ in Formula (A3) or Formula (A4) have the same meanings as R ¹ and X ¹ in Formula (A2), a preferred range is also the same.
The vinyl moiety containing R ¹ and X ¹ in formula (A3) or formula (A4) is bonded at any position on each alicyclic hydrocarbon structure shown below in formula (A3) or formula (A4). Can do.

R ³ and R ⁴ in Formula (A3) or Formula (A4) each independently represent a substituent, and are bonded at any position on each alicyclic hydrocarbon structure in Formula (A3) or Formula (A4). can do. Substituents in R ³ and R ⁴ has the same meaning as the substituent in R ² of formula (A2), a preferred range is also the same.
In formula (A3) or formula (A4), s and t each independently represent an integer of 0 to 5, and s R ³ and t R ⁴ are the same or different. May be.

  As the monomer represented by the formula (A2), preferred specific examples of monofunctional acrylates are shown below.

  As the monomer represented by the formula (A2), preferred specific examples of monofunctional methacrylate are shown below.

  As the monomer represented by the formula (A2), preferred specific examples of monofunctional acrylamide are shown below.

(Cationically polymerizable compound)
The cationic polymerizable compound that can be used in the present invention is not particularly limited as long as it is a compound that initiates a polymerization reaction by a cationic polymerization initiating species generated from a cationic polymerization initiator described later and cures. Various known cationic polymerizable monomers can be used. Examples of the cationic polymerizable monomer include JP-A-6-9714, JP-A-2001-31892, JP-A-2001-40068, JP-A-2001-55507, JP-A-2001-310938, JP-A-2001-310937, and 2001-2001. Preferred examples include epoxy compounds, vinyl ether compounds, oxetane compounds and the like described in each publication such as 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.

(D) Polymerization initiator The ink composition of the present invention contains (D) a polymerization initiator.
A known polymerization initiator can be used as the polymerization initiator that can be used in the present invention. The polymerization initiator that can be used in the present invention may be used alone or in combination of two or more. Moreover, you may use together a radical polymerization initiator and a cationic polymerization initiator.
The polymerization initiator that can be used in the present invention is a compound that absorbs external energy and generates 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 radical polymerization initiator.

(Radical polymerization initiator)
The radical polymerization initiator that can be used in the present invention includes (a) aromatic ketones, (b) acylphosphine compounds, (c) aromatic onium salt compounds, (d) organic peroxides, and (e) thio compounds. (F) hexaarylbiimidazole compound, (g) ketoxime ester compound, (h) borate compound, (i) azinium compound, (j) metallocene compound, (k) active ester compound, (l) carbon halogen bond Compounds having (m) alkylamine compounds and the like. These radical polymerization initiators may use the above compounds (a) to (m) alone or in combination. The radical polymerization initiator in the present invention is preferably used alone or in combination of two or more.

  Preferable examples of (a) aromatic ketones and (e) thio compounds include “RADIATION CURING IN POLYMER SCIENCE AND TECHNOLOGY” P. FOUASSIER J.M. F. RABEK (1993), pp. Examples include compounds having a benzophenone skeleton or a thioxanthone skeleton described in 77-117. Preferred examples of (a) aromatic ketones, (b) acylphosphine compounds, and (e) thio compounds include α-thiobenzophenone compounds described in JP-B-47-6416, JP-B-47-3981. Benzoin ether compounds described in Japanese Patent Publication No. 47-22326, α-substituted benzoin compounds described in Japanese Patent Publication No. 47-22326, benzoin derivatives described in Japanese Patent Publication No. 47-23664, and aroylphosphonic acid esters described in Japanese Patent Publication No. 57-30704. Dialkoxybenzophenone described in JP-B-60-26483, benzoin ethers described in JP-B-60-26403, JP-A-62-81345, JP-B-1-34242, US Pat. No. 4,318 791, α-aminobenzopheno described in European Patent No. 0284561A1 P-di (dimethylaminobenzoyl) benzene described in JP-A-2-211452, thio-substituted aromatic ketone described in JP-A-61-194062, acylphosphine sulfide described in JP-B-2-9597, Examples thereof include acylphosphine described in JP-B-2-9596, thioxanthones described in JP-B-63-61950, and coumarins described in JP-B-59-42864.

  Examples of the benzophenone compound include benzophenone, 4-phenylbenzophenone, isophthalophenone, 4-benzoyl-4'-methylphenyl sulfide and the like. Examples of the thioxanthone compound include 2,4-diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone and the like.

Further, (a) the aromatic ketone is preferably α-hydroxyketone, such as 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one, Examples include 2-hydroxy-2-methyl-1-phenylpropan-1-one and 1-hydroxycyclohexyl phenyl ketone.
Among these, as the (a) aromatic ketone, a 1-hydroxycyclohexyl phenyl ketone compound is particularly preferable. In the present invention, the 1-hydroxycyclohexyl phenyl ketone compound means a compound in which 1-hydroxycyclohexyl phenyl ketone and 1-hydroxycyclohexyl phenyl ketone are substituted with an arbitrary substituent. The substituent can be arbitrarily selected as long as it can exhibit the ability as a radical polymerization initiator, and specific examples thereof include alkyl groups (eg, methyl group, ethyl group, propyl group, butyl group). it can.

Moreover, as the (b) acylphosphine compound, an acylphosphine oxide compound is preferable.
Examples of the acylphosphine oxide compound include those having the structural formula of formula (7) or formula (8) in the structure of the compound.

  In particular, as the acylphosphine oxide compound, those having a chemical structure of the formula (9) or the formula (10) are particularly preferable.

（式中、Ｒ₆、Ｒ₇、Ｒ₈はメチル基又はエチル基を置換基として有していてもよい芳香族炭化水素基を表す。）

(In the formula, R ₆ , R ₇ and R ₈ represent an aromatic hydrocarbon group which may have a methyl group or an ethyl group as a substituent.)

（式中、Ｒ₉、Ｒ₁₀、Ｒ₁₁はメチル基又はエチル基を置換基として有していてもよい芳香族炭化水素基を表す。）

(In formula, R < ₉ >, R < ₁₀ >, R < ₁₁ > represents the aromatic hydrocarbon group which may have a methyl group or an ethyl group as a substituent.)

  As the acylphosphine oxide compound, a monoacylphosphine oxide compound, a bisacylphosphine oxide compound, or the like can be used. As the monoacylphosphine oxide compound, a known monoacylphosphine oxide compound can be used. Examples thereof include monoacylphosphine oxide compounds described in Japanese Patent Publication No. 60-8047 and Japanese Patent Publication No. 63-40799. Specific examples include isobutyrylmethylphosphinic acid methyl ester, isobutyrylphenylphosphinic acid methyl ester, pivaloylphenylphosphinic acid methyl ester, 2-ethylhexanoylphenylphosphinic acid methyl ester, pivaloylphenylphosphinic acid isopropyl Ester, p-toluylphenylphosphinic acid methyl ester, o-toluylphenylphosphinic acid methyl ester, 2,4-dimethylbenzoylphenylphosphinic acid methyl ester, pt-butylbenzoylphenylphosphinic acid isopropyl ester, acryloylphenylphosphinic acid methyl ester , Isobutyryl diphenyl phosphine oxide, 2-ethylhexanoyl diphenyl phosphine oxide, o-toluyl diphenyl phosphite Oxide, pt-butylbenzoyldiphenylphosphine oxide, 3-pyridylcarbonyldiphenylphosphine oxide, acryloyl-diphenylphosphine oxide, benzoyldiphenylphosphine oxide, pivaloylphenylphosphinic acid vinyl ester, adipoylbisdiphenylphosphine oxide, pivaloyl Diphenylphosphine oxide, p-toluyldiphenylphosphine oxide, 4- (t-butyl) benzoyldiphenylphosphine oxide, terephthaloylbisdiphenylphosphine oxide, 2-methylbenzoyldiphenylphosphine oxide, versatoyldiphenylphosphine oxide, 2-methyl-2 -Ethylhexanoyldiphenylphosphine oxide, 1- Chill cyclohexanoyl diphenylphosphine oxide, pivaloyl phenyl phosphinic acid methyl ester and pivaloyl phenyl phosphinic acid isopropyl ester.

  A known bisacylphosphine oxide compound can be used as the bisacylphosphine oxide compound. Examples thereof include bisacylphosphine oxide compounds described in JP-A-3-101686, JP-A-5-345790, and JP-A-6-298818. Specific examples include bis (2,6-dichlorobenzoyl) phenylphosphine oxide, bis (2,6-dichlorobenzoyl) -2,5-dimethylphenylphosphine oxide, bis (2,6-dichlorobenzoyl) -4-ethoxy. Phenylphosphine oxide, bis (2,6-dichlorobenzoyl) -4-propylphenylphosphine oxide, bis (2,6-dichlorobenzoyl) -2-naphthylphosphine oxide, bis (2,6-dichlorobenzoyl) -1-naphthyl Phosphine oxide, bis (2,6-dichlorobenzoyl) -4-chlorophenylphosphine oxide, bis (2,6-dichlorobenzoyl) -2,4-dimethoxyphenylphosphine oxide, bis (2,6-dichlorobenzoyl) decylphosphite Oxide, bis (2,6-dichlorobenzoyl) -4-octylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,5- Dimethylphenylphosphine oxide, bis (2,6-dichloro3,4,5-trimethoxybenzoyl) -2,5-dimethylphenylphosphine oxide, bis (2,6-dichloro-3,4,5-trimethoxybenzoyl) -4-ethoxyphenylphosphine oxide, bis (2-methyl-1-naphthoyl) -2,5-dimethylphenylphosphine oxide, bis (2-methyl-1-naphthoyl) -4-ethoxyphenylphosphine oxide, bis (2- Methyl-1-naphthoyl) -2-naphthy Phosphine oxide, bis (2-methyl-1-naphthoyl) -4-propylphenylphosphine oxide, bis (2-methyl-1-naphthoyl) -2,5-dimethylphenylphosphine oxide, bis (2-methoxy-1-naphthoyl) ) -4-engineered phenylphenylphosphine oxide, bis (2-chloro-1-naphthoyl) -2,5-dimethylphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide Etc.

  Among these, in the present invention, as the acylphosphine oxide compound, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (Irgacure 819: manufactured by Ciba Specialty Chemicals), bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Darocur TPO: Ciba Specialty Chemicals, Lucirin TPO: BASF) and the like are preferable.

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

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

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

  (G) Examples of the ketoxime ester compound include 3-benzoyloxyiminobutane-2-one, 3-acetoxyiminobutane-2-one, 3-propionyloxyiminobutane-2-one, and 2-acetoxyiminopentane-3. -One, 2-acetoxyimino-1-phenylpropan-1-one, 2-benzoyloxyimino-1-phenylpropan-1-one, 3-p-toluenesulfonyloxyiminotan-2-one, 2-ethoxy And carbonyloxyimino-1-phenylpropan-1-one.

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

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

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

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

  (K) Examples of active ester compounds include the specifications of European Patent Nos. 0290750, 046083, 156153, 271851 and 0388343, the specifications of US Pat. Nos. 3,901,710 and 4,181,531, Nitrobenzester compounds described in JP-A-60-198538 and JP-A-53-133022, European Patent Nos. 0199672, 84515, 199672, 0441115, and 0101122 Specification, U.S. Pat. Nos. 4,618,564, 4,371,605 and 4,431,774, and JP-A-64-18143, JP-A-2-245756, and JP-A-4-365048 , Shoko 62-6223, Shoko 63-14 Like compounds described in each publication of No. 40 and JP 59-174831 and the like.

  (L) Preferred examples of the compound having a carbon halogen bond include, for example, a compound described in Wakabayashi et al., Bull. Chem. Soc. Japan, 42, 2924 (1969), a compound described in British Patent No. 1388492, Examples include compounds described in JP-A No. 53-133428, compounds described in German Patent No. 3333724, and the like.

  Further, compounds described in J. Org. Chem., 29, 1527 (1964), compounds described in JP-A-62-258241, compounds described in JP-A-5-281728, etc. by FC Schaefer et al. it can. A compound as described in German Patent No. 2641100, a compound as described in German Patent No. 3333450, a group of compounds as described in German Patent No. 3021590, a group of compounds as described in German Patent No. 3021599, etc. Can be mentioned.

(Cationic polymerization initiator)
In the present invention, when a cationic polymerizable compound is used, it is preferable to use a cationic polymerization initiator. As the cationic polymerization initiator (photoacid generator) that can be used in the present invention, for example, a chemical amplification type photoresist or a compound used for photocationic polymerization is used (Organic Electronics Materials Research Group, “For Imaging”). “Organic materials”, Bunshin Publishing (1993), pages 187-192). Examples of the cationic polymerization initiator suitable for the present invention are listed below.

First, B (C ₆ F ₅ ) ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , CF ₃ SO ₃ ⁻ salt of aromatic onium compounds such as diazonium, ammonium, iodonium, sulfonium, phosphonium, etc. be able to. Secondly, sulfonated products that generate sulfonic acid can be mentioned. Thirdly, a halide that generates hydrogen halide can also be used. Fourthly, iron arene complexes can be mentioned.

  The content of the (D) polymerization initiator in the ink composition of the present invention is preferably 0.01 to 35% by weight, and preferably 0.5 to 20% by weight with respect to the total content of the polymerizable compounds. More preferably, it is 1.0 to 15% by weight. When the content is 0.01% by weight or more, the composition can be sufficiently cured, and when it is 35% by weight or less, a cured film having a uniform degree of curing can be obtained.

(E) Dispersant The ink composition of the present invention preferably contains (E) a dispersant, and when a pigment is used as a colorant, the pigment is stably dispersed in the ink composition. ) It is particularly preferred to contain a dispersant.
As the dispersant that can be used in the present invention, a polymer dispersant is preferable. The “polymer dispersing agent” in the present invention means a dispersing agent having a weight average molecular weight of 1,000 or more.

Dispersor BYK-101, DisperBYK-102, DisperBYK-103, DisperBYK-106, DisperBYK-111, DisperBYK-161, DisperBYK-162, DisperBYK-164D, DisperBYK-164D, , DisperBYK-168, DisperBYK-170, DisperBYK-171, DisperBYK-174, DisperBYK-182 (manufactured by BYK Chemie), EFKA4010, EFKA4046, EFKA4080, EFKA5010, EFKA5504, EFKA5207E Polymer dispersing agents such as EFKA7462, EFKA7500, EFKA7570, EFKA7575, EFKA7580 (manufactured by Efka Additives), Disperse Aid 6, Disperse Aid 8, Disperse Aid 15, Disperse Aid 9100 (Sannopco) Solsperse (Solsperse) 3000, 5000, 9000, 12000, 13240, 13940, 17000, 22000, 24000, 26000, 28000, 32000, 36000, 39000, 41000, 71000, etc. (Abyssia); L31, F38, L42, L44, L61, L64, F68, L72, P95, F77, P84, F87, P94, L101, P103, F10 , L121, P-123 (Asahi Denka Co., Ltd.) and Isonet S-20 (Sanyo Kasei Co., Ltd.), Enomoto Kasei Co., Ltd. “Disparon KS-860, 873SN, 874 (polymer dispersant), # 2150 (aliphatic polyvalent carboxylic acid), # 7004 (polyether ester type) ”.
The content of the dispersant in the ink composition is appropriately selected depending on the purpose of use, but is preferably 0.05 to 15% by weight with respect to the total weight of the ink composition.

  In the present invention, the weight ratio of the dispersant to the colorant (preferably pigment) is such that when the weight of the colorant in the ink composition is A and the weight E of the dispersant in the ink composition is the weight ratio ( E / A) is preferably 0.01 ≦ E / A ≦ 5, more preferably 0.05 ≦ E / A ≦ 2.5, and 0.1 ≦ E / A ≦ 1. More preferably. Within the above range, aggregation and sedimentation of the pigment after storage over time, increase in the viscosity of the ink composition does not occur, the ink composition is excellent in storage stability over time, and the viscosity of the ink composition is low viscosity, The ink composition is excellent in ejection stability.

(F) Other components Other components other than the above components can be added to the ink composition of the present invention, if necessary.
Examples of other components include strong sensitizers, surfactants, ultraviolet absorbers, antioxidants, antifading agents, conductive salts, solvents, polymer compounds, basic compounds, and the like.

<Strong sensitizer>
The ink composition of the present invention preferably contains a strong sensitizer (sometimes referred to as “co-sensitizer” or “supersensitizer”). In the present invention, the strong sensitizer further enhances the sensitivity of the sensitizer to actinic radiation, or has an action of suppressing the polymerization inhibition of the polymerizable compound by oxygen.
Examples of such a strong sensitizer 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. , JP-A-52-134692, JP-A-59-138205, JP-A-60-84305, JP-A-62-18537, JP-A-64-33104, Research Disclosure And compounds described in No. 33825.
Specific examples include triethanolamine, p-dimethylaminobenzoic acid ethyl ester, p-formyldimethylaniline, p-methylthiodimethylaniline and the like.

Other examples of strong sensitizers include thiols and sulfides such as thiol compounds described in JP-A-53-702, JP-B-55-500806, JP-A-5-142772, The disulfide compound of 56-75643 gazette etc. are mentioned.
Specific examples include 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, 2-mercaptobenzimidazole, 2-mercapto-4 (3H) -quinazoline, β-mercaptonaphthalene and the like.

Other examples include amino acid compounds (eg, N-phenylglycine), organometallic compounds described in Japanese Patent Publication No. 48-42965 (eg, tributyltin acetate), and hydrogen described in Japanese Patent Publication No. 55-34414. Donors, sulfur compounds described in JP-A-6-308727 (eg, trithiane), phosphorus compounds described in JP-A-6-250387 (diethyl phosphite etc.), Si-- described in JP-A-8-54735 H, Ge-H compound, etc. are mentioned.
The content of the strong sensitizer in the ink composition of the present invention is appropriately selected depending on the purpose of use, but is preferably 0.05 to 4% by weight with respect to the weight of the entire ink composition.

<Surfactant>
A surfactant is preferably added to the ink composition of the present invention in order to provide stable ejection properties for a long time.
Examples of the surfactant include those described in JP-A Nos. 62-173463 and 62-183457. For example, anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalenesulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, polyoxyethylene / polyoxypropylene blocks Nonionic surfactants such as copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. An organic fluoro compound may be used in place of the surfactant. The organic fluoro compound is preferably hydrophobic. Examples of the organic fluoro compounds include fluorine surfactants, oily fluorine compounds (eg, fluorine oil) and solid fluorine compound resins (eg, tetrafluoroethylene resin). No. (columns 8 to 17) and those described in JP-A Nos. 62-135826.
As the surfactant, polydialkylsiloxanes are preferable, and polyethoxy-modified polydimethylsiloxane is more preferable.
The content of the surfactant in the ink composition is appropriately selected depending on the purpose of use, but is preferably 0.0001 to 1% by weight based on the total weight of the ink composition.

<Ultraviolet absorber>
In the present invention, an ultraviolet absorber can be used from the viewpoint of improving the weather resistance of the obtained image and preventing discoloration.
Examples of the ultraviolet absorber are described in JP-A-58-185679, JP-A-61-190537, JP-A-2-782, JP-A-5-97075, JP-A-9-34057, and the like. Benzotriazole compounds, benzophenone compounds described in JP-A No. 46-2784, JP-A No. 5-194843, US Pat. No. 3,214,463, etc., JP-B Nos. 48-30492 and 56-21141 Cinnamic acid compounds described in JP-A-10-88106, JP-A-4-298503, JP-A-8-53427, JP-A-8-239368, JP-A-10-182621, JP The triazine compounds described in JP-A-8-501291, Research Disclosure No. Examples thereof include compounds described in US Pat. No. 24239, compounds that emit fluorescence by absorbing ultraviolet rays typified by stilbene and benzoxazole compounds, and so-called fluorescent brighteners.
Although the addition amount is appropriately selected according to the purpose, it is preferably 0.5 to 15% by weight in terms of solid content.

<Antioxidant>
An antioxidant can be added to improve the stability of the ink composition. Examples of the antioxidant include European Published Patent Nos. 223739, 309401, 309402, 310551, 310552, 457416, and German Patent No. 3435443. JP-A-54-48535, JP-A-62-262047, JP-A-63-113536, JP-A-63-163351, JP-A-2-262654, JP-A-2-71262, and JP-A-3 No. 112449, JP-A-5-61166, JP-A-5-119449, US Pat. No. 4,814,262, US Pat. No. 4,980,275, and the like.
Although the addition amount is appropriately selected according to the purpose, it is preferably 0.1 to 8% by weight in terms of solid content.

<Anti-fading agent>
In the ink composition of the present invention, various organic and metal complex anti-fading agents can be used. Examples of the organic anti-fading agent include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, and heterocycles. Examples of the metal complex-based antifading agent include nickel complexes and zinc complexes. No. 17643, Nos. VII to I, J. 15162, ibid. No. 18716, page 650, left column, ibid. No. 36544, page 527, ibid. No. 307105, page 872, ibid. The compounds described in the patent cited in No. 15162 and the compounds included in the general formulas and compound examples of representative compounds described in JP-A-62-215272, pages 127 to 137 can be used. .
Although the addition amount is appropriately selected according to the purpose, it is preferably 0.1 to 8% by weight in terms of solid content.

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

<Solvent>
In order to improve the adhesion to the recording medium, it is also effective to add a very small amount of an organic solvent to the ink composition of the present invention.
Examples of the solvent include ketone solvents such as acetone, methyl ethyl ketone, and diethyl ketone, alcohol solvents such as methanol, ethanol, 2-propanol, 1-propanol, 1-butanol, and tert-butanol, and chlorine such as chloroform and methylene chloride. Solvents, aromatic solvents such as benzene and toluene, ester solvents such as ethyl acetate, butyl acetate and isopropyl acetate, ether solvents such as diethyl ether, tetrahydrofuran and dioxane, glycols such as ethylene glycol monomethyl ether and ethylene glycol dimethyl ether Examples include ether solvents.
In this case, it is effective to add the solvent within the range that does not cause the problem of solvent resistance and VOC, and the amount is preferably 0.1 to 5% by weight, more preferably 0.1 to 3% by weight based on the whole ink composition. % Range.

<Polymer compound>
Various polymer compounds can be added to the ink composition of the present invention in order to adjust film physical properties. High molecular compounds include acrylic resin, polyvinyl butyral resin, polyurethane resin, polyamide resin, polyester resin, epoxy resin, phenol resin, polycarbonate resin, polyvinyl butyral resin, polyvinyl formal resin, shellac, vinyl resin, acrylic resin, rubber Resins, waxes, other natural resins, etc. can be used. Two or more of these may be used in combination. Of these, vinyl copolymer obtained by copolymerization of acrylic monomers is preferred. Furthermore, as a copolymer composition of the polymer compound, a copolymer containing “carboxyl group-containing monomer”, “alkyl methacrylate ester” or “alkyl acrylate ester” as a structural unit is also preferably used.

<Basic compound>
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. .

In addition to this, if necessary, for example, leveling additives, matting agents, waxes for adjusting film physical properties, polymerization to inhibit the adhesion to recording media such as polyolefin and PET, and the like, The tackifier which does not do can be contained.
As the tackifier, specifically, a high molecular weight adhesive polymer described in JP-A-2001-49200, 5-6p (for example, (meth) acrylic acid and an alkyl group having 1 to 20 carbon atoms). An ester with an alcohol having, an ester of (meth) acrylic acid with an alicyclic alcohol having 3 to 14 carbon atoms, a copolymer comprising an ester of (meth) acrylic acid with an aromatic alcohol having 6 to 14 carbon atoms) And a low molecular weight tackifier resin having a polymerizable unsaturated bond.

[Ink properties]
In the present invention, in consideration of dischargeability, the viscosity of the ink composition at 25 ° C. is preferably 40 mPa · s or less, more preferably 5 to 40 mPa · s, and more preferably 7 to 30 mPa · s. Is more preferable. Moreover, it is preferable that the viscosity in discharge temperature (Preferably 25-80 degreeC, More preferably, 25-50 degreeC) is 3-15 mPa * s, and it is more preferable that it is 3-13 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, penetration of the ink composition into the recording medium can be avoided, and uncured monomers can be reduced. Furthermore, it is preferable because ink bleeding at the time of landing of the ink composition droplets can be suppressed, and as a result, the image quality is improved.

  The surface tension of the ink composition of the present invention at 25 ° C. is preferably 20 to 35 mN / m, and more preferably 23 to 33 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 35 mN / m or less is preferable in terms of wettability.

(2) Inkjet recording method, inkjet recording apparatus, and printed material The ink composition of the present invention is suitably used for inkjet recording.
In the inkjet recording method of the present invention, the ink composition of the present invention is ejected onto a recording medium (support, recording material, etc.) for inkjet recording, and actinic radiation is applied to the ink composition ejected onto the recording medium. It is a method of forming an image by irradiating and curing the ink.

More specifically, the inkjet recording method of the present invention comprises (a ¹ ) a step of ejecting the ink composition of the present invention onto a recording medium, and (b ¹ ) actinic radiation on the ejected ink composition. And a step of curing the ink composition.
By including the steps (a ¹ ) and (b ¹ ), the ink jet recording method of the present invention forms an image with the ink composition cured on the recording medium.
The printed matter of the present invention is a printed matter obtained by using the ink composition of the present invention, and is preferably a printed matter recorded by the inkjet recording method of the present invention.

In the step (a ¹ ) in the ink jet recording method of the present invention, an ink jet recording apparatus described in detail below can be used.

[Inkjet recording device]
There is no restriction | limiting in particular as an inkjet recording device used for the inkjet recording method of this invention, The well-known inkjet recording device which can achieve the target resolution can be selected arbitrarily and can be used. That is, any known inkjet recording apparatus including a commercially available product can eject ink onto a recording medium in the step (a ¹ ) of the inkjet recording method of the present invention.
Examples of the ink jet recording apparatus that can be used in the present invention include an apparatus including 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 preferably has a multi-size dot of 1 to 100 pl, more preferably 8 to 30 pl, preferably 320 × 320 to 4,000 × 4,000 dpi, more preferably 400 × 400 to 1,600 ×. It can be driven so that it can discharge at a resolution of 1,600 dpi, more preferably 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, like the ink composition of the present invention, has a constant temperature for the ink to be ejected, heat insulation and heating are performed from the ink supply tank to the inkjet head portion. It can be carried out. 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 heat energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

Using the above inkjet recording apparatus, the ink composition of the present invention is ejected by heating the ink composition to preferably 25 to 80 ° C., more preferably 25 to 50 ° C. Preferably it is performed after lowering to 3 to 15 mPa · s, more preferably 3 to 13 mPa · s. In particular, it is preferable to use an ink composition having an ink viscosity at 25 ° C. of 50 mPa · s or less as the ink composition of the present invention, since it can be discharged satisfactorily. 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 usually used in ink jet recording inks, and therefore has a large viscosity fluctuation due to temperature fluctuations during ejection. 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, the control range of the ink temperature is preferably set to ± 5 ° C. of the set temperature, more preferably ± 2 ° C. of the set temperature, and further preferably set to ± 1 ° C.

Next, the step (b ¹ ) of curing the ink composition by irradiating the discharged ink composition with actinic radiation will be described.
The ink composition ejected on the recording medium is cured by irradiation with actinic radiation. This is because the polymerization initiator contained in the ink composition of the present invention is decomposed by irradiation with actinic radiation to generate radicals, acids, bases, and other starting species, and the function of the starting species is polymerization of a radical polymerizable compound. This is because the reaction occurs and is accelerated. At this time, if a sensitizer is present together with the polymerization initiator in the ink composition, the sensitizer in the system absorbs actinic radiation to be in an excited state, and promotes decomposition of the polymerization initiator by contacting with the polymerization initiator. And a more sensitive curing reaction can be achieved.

  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. Although the peak wavelength of actinic radiation is based also on the absorption characteristic of a sensitizer, it is preferable that it is 200-600 nm, for example, it is more preferable that it is 300-450 nm, and it is further more preferable that it is 350-420 nm.

In addition, the polymerization initiation system of the ink composition of the present invention has sufficient sensitivity even with a low output actinic radiation. Therefore, it is appropriate that the exposure surface illuminance is preferably 10 to 4,000 mW / cm ² , more preferably 20 to 2,500 mW / cm ² .

Mercury lamps and gas / solid lasers are mainly used as actinic radiation sources, and mercury lamps and metal halide lamps are widely known as light sources used for curing UV photocurable ink jet recording inks. Yes. 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 lifetime, high efficiency, and low cost, and are expected as light sources for photo-curable 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.
Incidentally, 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, is 50 to 800 mW / cm ² It is particularly preferred.

The ink composition of the present invention is appropriately irradiated with such actinic radiation for 0.01 to 120 seconds, more 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 period of time (preferably 0.01 to 0.5 seconds, more preferably 0.01 to 0.3 seconds, still 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. In addition, since it can be exposed to the porous recording medium before the ink penetrates to a deep part where the light source does not reach, it is preferable because residual unreacted monomer can be suppressed.
Further, the curing may be completed by another light source that is not driven. International Publication No. 99/54415 pamphlet discloses a method using an optical fiber or a method of irradiating a recording unit with UV light by applying a collimated light source to a mirror surface provided on the side of the head unit as an irradiation method. Such a curing method can also be applied to the ink jet recording method of the present invention.

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, it becomes easier for the irradiation line to reach the lower ink, and good curing sensitivity, reduction of residual monomers, and improvement in 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 can form an image on the surface of a recording medium by being cured with high sensitivity by irradiation with actinic radiation.

  In the ink jet recording method of the present invention, the ink set of the present invention can be suitably used. The order of the colored ink compositions to be ejected is not particularly limited, but it is preferably applied to the recording medium from the colored ink composition having a low brightness, and the ink composition of the present invention and yellow, cyan, magenta When black is used, it is preferably applied on the recording medium in the order of the ink composition of the present invention → yellow → cyan → magenta → black. When white is used in addition to this, it is preferably applied on the recording medium in the order of white → the ink composition of the present invention → yellow → cyan → magenta → black. Further, the present invention is not limited to this, and includes at least eight colors of the ink composition of the present invention of light cyan, light magenta, and light black and the dark ink composition of cyan, magenta, gray, black, white, and yellow. The ink set of the present invention can be preferably used, and in this case, it is preferably applied on the recording medium in the order of white → light cyan → light magenta → light black → yellow → cyan → magenta → black.

  In the present invention, the recording medium is not particularly limited, and a known recording medium can be used as a support or a recording material. 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.), and paper or plastic films on which the above-mentioned metals are laminated or deposited. In addition, as the recording medium in the present invention, a non-absorbable recording medium can be preferably used.

(Ink set)
The ink set of the present invention may be an ink set having at least one ink composition of the present invention and having two or more ink compositions in combination with the ink composition of the present invention or an ink composition other than the present invention. For example, although there is no particular limitation, it is preferable to include at least one ink composition of the present invention having a color selected from the group consisting of light magenta, light cyan, and light black (gray), and light magenta and light cyan. It is more preferable to include at least one ink composition of the present invention having a color selected from the group consisting of, and it is even more preferable to include the light magenta and light cyan ink compositions of the present invention.
The ink set of the present invention can be suitably used for the ink jet recording method of the present invention.
In order to obtain a full-color image using the ink composition of the present invention, the ink set of the present invention includes a dark ink composition of four colors consisting of yellow, cyan, magenta, and black and the ink composition of the present invention. It is preferable that the ink set is a combination of at least one, and the ink set is a combination of at least one of the dark ink composition of five colors consisting of yellow, cyan, magenta, black and white and the ink composition of the present invention. More preferably, the ink set is a combination of five color ink compositions consisting of yellow, cyan, magenta, black and white and three ink compositions of the present invention consisting of light cyan, light magenta and light black. Is more preferable.
The “dark color ink composition” in the present invention means an ink composition in which the content of the colorant exceeds 2% by weight of the entire ink composition. There is no restriction | limiting in particular as said coloring agent, A well-known coloring agent can be used, A pigment and oil-soluble dye can be illustrated.
Needless to say, the ink set of the present invention may contain an ink composition not containing the compound represented by the formula (I).

  The ink set of the present invention includes at least one dark color ink composition and the ink composition of the present invention, and the dark color ink composition and the ink composition of the present invention use a colorant having a similar color. The ratio of the colorant concentration between the dark color ink composition and the ink composition of the present invention is preferably dark color ink composition: light color ink composition = 15: 1 to 4: 1, : 1 to 4: 1 is more preferable, and 10: 1 to 4.5: 1 is still more preferable. Within the above range, a vivid full-color image with little graininess can be obtained.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to these examples.
In the following description, “parts” means “parts by weight” unless otherwise specified.

The materials of the ink composition (radical polymerizable ink composition) used in the present invention are as shown below.
・ IRGALITE BLUE GLVO (Cyan Pigment, Ciba Specialty Chemicals)
・ CINQUASIA MAGENTA RT-335 D (Magenta pigment, manufactured by Ciba Specialty Chemicals)
・ NOVOPERM YELLOW H2G (yellow pigment, manufactured by Clariant)
SPECIAL BLACK 250 (black pigment, manufactured by Ciba Specialty Chemicals)
・ Taipeku CR60-2 (white pigment, manufactured by Ishihara Sangyo Co., Ltd.)
・ N-Vinylcaprolactam (NVC, manufactured by BASF)
SR9003 (propylene glycol modified neopentyl glycol diacrylate, manufactured by Sartomer)
Solsperse 36000 (Noveon dispersant)
DisperBYK-168 (BYK168, BYK Chemie polymer dispersant, solid content 30%)
-NK ester AMP-10G (NK AMP-10G, PEA (phenoxyethyl acrylate), manufactured by Shin-Nakamura Chemical Co., Ltd.)
-Rapi-Cure DVE-3 (DVE-3, triethylene glycol divinyl ether, manufactured by ISP Europe)
FIRSTCURE ST-1 (polymerization inhibitor, manufactured by Chem First)
BYK307 (polyether-modified dimethylsiloxane, manufactured by BYK Chemie)
IRGACURE 819 (polymerization initiator, bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, manufactured by Ciba Specialty Chemicals)
IRGACURE 184 (polymerization initiator, 1-hydroxycyclohexyl phenyl ketone, manufactured by Ciba Specialty Chemicals)
Darocur TPO (polymerization initiator, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, manufactured by Ciba Specialty Chemicals)
・ Benzophenone (polymerization initiator, manufactured by Wako Pure Chemical Industries, Ltd.)
Compound represented by formula (I) (Exemplary compounds (I-4), (I-14), (I-17), (I-71), (I-116), (I-129))

FIRSTCURE ITX (sensitizer, manufactured by Chem First, comparative example)

(Preparation of cyan mill base A)
300 parts by weight of IRGALITE BLUE GLVO, 400 parts by weight of NK AMP-10G, and 300 parts by weight of BYK168 were mixed with stirring to obtain cyan mill base A. Cyan mill base A was prepared in a disperser motor mill M50 (manufactured by Eiger) and dispersed for 4 hours at a peripheral speed of 9 m / s using zirconia beads having a diameter of 0.65 mm.

(Preparation of magenta mill base A)
300 parts by weight of CINQUASIA MAGENTA RT-335 D, 400 parts by weight of NK AMP-10G, and 300 parts by weight of BYK168 were mixed with stirring to obtain magenta mill base A. The magenta mill base A was prepared in a disperser motor mill M50 (manufactured by Eiger) and dispersed for 8 hours at a peripheral speed of 9 m / s using zirconia beads having a diameter of 0.65 mm.

(Preparation of yellow mill base A)
300 parts by weight of NOVOPERM YELLOW H2G, 400 parts by weight of NK AMP-10G, and 300 parts by weight of BYK168 were mixed with stirring to obtain yellow mill base A. The yellow mill base A was prepared in a disperser motor mill M50 (manufactured by Eiger) and dispersed for 8 hours at a peripheral speed of 9 m / s using zirconia beads having a diameter of 0.65 mm.

(Preparation of black mill base A)
300 parts by weight of SPECIAL BLACK 250, 400 parts by weight of NK AMP-10G, and 300 parts by weight of BYK168 were stirred and mixed to obtain Black Mill Base A. The black mill base A was prepared in a disperser motor mill M50 (manufactured by Eiger) and dispersed for 6 hours at a peripheral speed of 9 m / s using zirconia beads having a diameter of 0.65 mm.

(Preparation of white mill base A)
A white mill base A was obtained by stirring and mixing 500 parts by weight of Tyco CR60-2, 450 parts by weight of NK AMP-10G, and 50 parts by weight of Solsperse 36000. The white mill base A was prepared in a disperser motor mill M50 (manufactured by Eiger) and dispersed for 3 hours at a peripheral speed of 9 m / s using zirconia beads having a diameter of 0.65 mm.

(Preparation of ink composition)
<Examples 1-4>
By mixing each material with a stirrer at a ratio shown in Tables 1 to 4, ink compositions of each color were prepared, and ink sets 1 to 4 were obtained. The numerical values in the table indicate parts by weight, C represents cyan, M represents magenta, Y represents yellow, K represents black, and W represents white.

<Comparative Examples 1-4>
By mixing each material with a stirrer at the ratio shown in Tables 5 to 8, ink compositions of each color were prepared, and ink sets 5 to 8 were obtained. In addition, the numerical value in a table | surface shows a weight part.

<Comparative Examples 5-8>
Each material was mixed at a ratio shown in Tables 9 to 12 with a stirrer to prepare ink compositions of each color, and ink sets 9 to 12 were obtained. In addition, the numerical value in a table | surface shows a weight part.

<Inkjet image recording method>
Using ink sets 1 to 12, color printed images 1 to 12 having an average film thickness of 12 μm were prepared by the following inkjet recording method.
As an inkjet recording method, recording on a recording medium was performed using an inkjet recording experimental apparatus having a piezo-type 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 nozzle of the ink jet head, respectively, and temperature control was performed so that the nozzle portion was always 45 ° 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 1,630 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 integrated light amount irradiated to the image was set to 1,000 mJ / cm ² . As an ultraviolet lamp, a HAN250NL high-cure mercury lamp (manufactured by GS Yuasa Corporation) was used. In the present invention, dpi represents the number of dots per 2.54 cm. As a recording medium, an ester film E5000 (thickness 125 μm, manufactured by Toyobo Co., Ltd.) was used.

(Measurement method of curing sensitivity)
According to the inkjet recording method, each color solid image having an average film thickness of 12 μm was drawn, and the degree of stickiness of the image was evaluated by palpation on the image surface after the ultraviolet irradiation.
The curing sensitivity was evaluated according to the following criteria.
3: No stickiness in the image.
2: The image is slightly sticky.
1: Uncured ink is not hard enough to transfer to hand.

(Measurement method of color difference in light color image area)
The color difference ΔE is the chromaticity (a ^{* 1} , b ^{* 1} ) and lightness (L ¹ ) of the light color image portion, and the chromaticity (a ^{* 2} , b) of the light color image portion without the sensitizer of the comparative example. ^{* 2} ) and lightness (L ² ) were measured with SPM100-II manufactured by Gretag, and ΔE was calculated by the following formula.
ΔE = {(a ^{* 1−} a ^{* 2} ) ² + (b ^{* 1−} b ^{* 2} ) ² + (L ¹ −L ² ) ² } ^1/2
A smaller ΔE is preferable because the color change is small. When ΔE is 1.0 or less, color reproducibility in light colors is particularly excellent.

  The evaluation results of ink sets 1 to 12 are shown in Tables 13 to 15.

(Preparation of ink composition)
<Examples 5 to 8>
Each material was mixed at a ratio shown in Tables 16 to 19 with a stirrer to prepare ink compositions of each color, and ink sets 13 to 16 were obtained. In addition, the numerical value in a table | surface shows a weight part.

<Comparative Examples 9-12>
Each material was mixed at a ratio shown in Tables 20 to 23 with a stirrer to prepare ink compositions of each color, and ink sets 20 to 23 were obtained. In addition, the numerical value in a table | surface shows a weight part.

<Comparative Examples 13-16>
Each material was mixed at a ratio shown in Tables 24-27 with a stirrer to prepare ink compositions of each color, and ink sets 21-24 were obtained. In addition, the numerical value in a table | surface shows a weight part.

<Inkjet image recording method>
Using the ink sets 13 to 24, color printing images 13 to 24 having an average film thickness of 12 μm are prepared by the inkjet recording method, and the evaluation of curing sensitivity and the color difference in the light color image portion are performed as described above. evaluated.
The evaluation results are shown in Tables 28-30.

<Examples 13 to 16>
Except having replaced exemplary compound (I-14) with exemplary compound (I-17), the ink composition of each color was produced similarly to Examples 1-4, and the ink sets 25-28 were obtained, respectively.
Using the ink sets 25 to 28, color printed images 25 to 28 having an average film thickness of 12 μm were produced by the inkjet recording method.
When the evaluation of the curing sensitivity of the ink sets 25 to 28 and the color difference in the light color image portion were evaluated in the same manner as described above on the basis of the color print images 9 to 12 similarly obtained from the ink sets 9 to 12, respectively, The results were the same as in Examples 5-8.

<Examples 17 to 20>
Except that the exemplified compound (I-14) was replaced with the exemplified compound (I-129), ink compositions of each color were prepared in the same manner as in Examples 1 to 4, and ink sets 29 to 32 were obtained, respectively.
Using ink sets 29 to 32, color printed images 29 to 32 having an average film thickness of 12 μm were prepared by the inkjet recording method.
When the evaluation of the curing sensitivity of the ink sets 29 to 32 and the color difference in the light color image portion were evaluated in the same manner as described above based on the color print images 9 to 12 similarly obtained from the ink sets 9 to 12, respectively, The results were the same as in Examples 5-8.

<Examples 21 to 24>
Except that the exemplified compound (I-14) was replaced with the exemplified compound (I-71), ink compositions of each color were prepared in the same manner as in Examples 1 to 4, and ink sets 33 to 36 were obtained.
Using the ink sets 33 to 36, color printed images 33 to 36 having an average film thickness of 12 μm were produced by the inkjet recording method.
When the evaluation of the curing sensitivity of the ink sets 33 to 36 and the color difference in the light color image portion were evaluated in the same manner as described above based on the color print images 9 to 12 similarly obtained from the ink sets 9 to 12, respectively, The results were the same as in Examples 5-8.

<Examples 25 to 28>
Except that the exemplified compound (I-14) was replaced with the exemplified compound (I-116), ink compositions of each color were prepared in the same manner as in Examples 1 to 4, and ink sets 37 to 40 were obtained.
Using the ink sets 37 to 40, color printed images 37 to 40 having an average film thickness of 12 μm were produced by the inkjet recording method.
When the evaluation of the curing sensitivity of the ink sets 37 to 40 and the color difference in the light color image portion were evaluated in the same manner as described above on the basis of the color print images 9 to 12 similarly obtained from the ink sets 9 to 12, respectively, The results were the same as in Examples 5-8.

Claims (10)

(A) a colorant,
(B) a compound represented by formula (I),
(C) a polymerizable compound, and
(D) contains a polymerization initiator,
The ink composition, wherein the content of the colorant (A) is 2% by weight or less of the whole ink composition.

(In the formula (I), X represents O, S, or NR, n represents 0 or 1, R represents a hydrogen atom, an alkyl group, or an acyl group, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ each independently represents a hydrogen atom or a monovalent substituent, and R ¹ , R ² , R ³ , and R ⁴ are Two adjacent to each other may be connected to each other to form a ring, and R ⁵ or R ⁶ and R ⁷ or R ⁸ may be connected to each other to form an aliphatic ring. It will not form.)   The ink composition according to claim 1, further comprising (E) a dispersant.   The ink composition according to claim 1, wherein the polymerizable compound (C) is an ethylenically unsaturated compound.   The ink composition according to claim 1, wherein the polymerizable compound (C) is a monofunctional polymerizable compound or a bifunctional polymerizable compound.   The ink composition according to claim 1, wherein the polymerization initiator (D) is a polymerization initiator selected from the group consisting of α-aminoketones and acylphosphine oxides.   The ink composition according to claim 1, wherein the colorant (A) is a magenta pigment or a cyan pigment.   The ink composition according to any one of claims 1 to 6, wherein the content of the compound represented by the formula (I) (B) is 0.05 to 30% by weight with respect to the entire ink composition. .   An ink set comprising at least one ink composition according to any one of claims 1 to 7. (A ¹⁾ onto a recording medium, a step of discharging the ink composition according to any one of claims 1 to 7 and,
(B ¹ ) An inkjet recording method comprising a step of irradiating the discharged ink composition with active radiation to cure the ink composition.   A printed matter recorded by the ink jet recording method according to claim 9.