JP2014240464A - Inkjet ink composition and inkjet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inkjet ink composition which gives excellent folding and bending durability of an image obtained therefrom, has a little elution amount (migration) to the outside of components in an ink film after cured, and gives little tackiness and odor of an image obtained therefrom, and to provide an inkjet recording method using the inkjet ink composition.SOLUTION: The inkjet ink composition comprises: (component A) a compound expressed by formula (1); (component B) a photopolymerization initiator having a molecular weight of 400 or more and 2000 or less; and (component C) a polyfunctional polymerizable compound except for the component A. The total content of the component A and the component C is 80 mass% or more with respect to the whole mass of polymerizable compounds in the ink composition.

Description

  The present invention relates to an inkjet ink composition and an inkjet recording method.

In recent years, an inkjet recording method has attracted attention as an image recording method for forming an image on a recording medium based on an image data signal. The inkjet recording method has an advantage that a high-definition image can be recorded at a low running cost by ejecting very fine droplets with less noise.
In particular, an ink composition for ink jet recording (a radiation curable ink composition for ink jet recording) that can be cured by irradiation with radiation such as ultraviolet rays is cured by irradiation with radiation such as ultraviolet rays, and most of the components of the ink composition are cured. It is an excellent method in that it can be printed on various recording media because it is excellent in drying properties compared to the solvent-based ink composition and the image is not easily smeared.
Examples of conventional ink compositions include Patent Documents 1 and 2.

International Publication No. 2013/008626 JP 2011-207960 A

  An object of the present invention is an inkjet ink composition having excellent folding resistance of an image to be obtained, a small amount of elution (migration) of components in the ink film after curing, and less stickiness and odor of the obtained image, and It is to provide an ink jet recording method using the ink jet ink composition.

The above-described problems of the present invention have been solved by the means described in <1> or <10> below. It is described below together with <2> to <9> which are preferred embodiments.
<1> (Component A) Compound represented by Formula (1), (Component B) Photopolymerization initiator having a molecular weight of 400 or more and 2,000 or less, and (Component C) a polyfunctional polymerizable compound other than Component A, An inkjet ink composition, wherein the total content of component A and component C is 80% by mass or more based on the total mass of the polymerizable compound in the ink composition,

（式（１）中、Ｒ¹はそれぞれ独立に、水素原子又はメチル基を表し、Ｌ¹はそれぞれ独立に、炭素原子数２〜４の直鎖又は分岐のアルキレン基を表し、また、Ｌ¹において、Ｌ¹の両端に結合する酸素原子と窒素原子とがＬ¹の同一の炭素原子に結合した構造をとることはなく、Ｌ²はそれぞれ独立に、２価の連結基を表し、ｋはそれぞれ独立に、２又は３を表し、ｘ、ｙ及びｚはそれぞれ独立に、０〜６の整数を表し、ｘ＋ｙ＋ｚは０〜１８を満たす。）

(In the formula (1), R ¹ each independently represent a hydrogen atom or a methyl group, L ¹ each independently represents a linear or branched alkylene group having 2 to 4 carbon atoms, also, L ¹ in not take an oxygen atom and a nitrogen atom bonded to both ends of the L ¹ is bonded to the same carbon atom of L ¹ structure, L ² each independently represents a divalent linking group, k is Each independently represents 2 or 3, x, y, and z each independently represent an integer of 0-6, and x + y + z satisfies 0-18.)

<2> Component C is at least one selected from the group consisting of dodecanediol diacrylate, 3-methyl-1,5-pentanediol diacrylate, trimethylolpropane triacrylate, and ethylene oxide-modified trimethylolpropane triacrylate. The inkjet ink composition according to the above <1>, comprising a seed compound;
<3> The total content of dodecanediol diacrylate, 3-methyl-1,5-pentanediol diacrylate, trimethylolpropane triacrylate, and ethylene oxide-modified trimethylolpropane triacrylate is component C in the ink composition. The inkjet ink composition according to <2>, which is 80% by mass or more based on the total mass of
<4> The inkjet ink composition according to any one of <1> to <3>, wherein the content of component A is 1 to 20% by mass with respect to the total mass of the ink composition
<5> The inkjet ink composition according to any one of <1> to <4>, wherein the total content of component A and component C is 50% by mass or more based on the total mass of the ink composition. ,
<6> The inkjet ink composition according to any one of <1> to <5>, wherein the total content of component A and component C is 70% by mass or more based on the total mass of the ink composition. ,
<7> The above-mentioned <1> to <6>, wherein the monofunctional polymerizable compound is not contained or the content of the monofunctional polymerizable compound is 10% by mass or less with respect to the total mass of the ink composition. The inkjet ink composition according to any one of the above,
<8> The inkjet ink composition according to any one of the above <1> to <7>, wherein Component B is an α-hydroxyketone compound,
<9> The inkjet ink composition according to any one of <1> to <8> above, which is an inkjet ink composition for printing food packages,
<10> (a ¹ ) A step of discharging the ink composition according to any one of the above <1> to <9> on a recording medium; and (b ¹ ) active on the discharged ink composition. An inkjet recording method comprising: a step of irradiating radiation to cure the ink composition.

  According to the present invention, an inkjet ink composition having excellent bending resistance of an image obtained, a small amount of elution (migration) to the outside of components in the ink film after curing, and less stickiness and odor of the obtained image, and An ink jet recording method using the above ink jet ink composition can be provided.

1 is a schematic diagram showing an example of an ink jet recording apparatus suitably used in the present invention. It is an expansion schematic diagram which shows an example of the inkjet head used suitably for this invention. It is an expansion schematic diagram which shows another example of the inkjet head used suitably for this invention. It is an external appearance perspective view of another example of the inkjet recording device used suitably for this invention. It is explanatory drawing which shows typically the recording-medium conveyance path in the inkjet recording device shown in FIG. FIG. 5 is a perspective plan view showing an arrangement of an inkjet head, a temporary curing light source, and a main curing light source in the inkjet recording apparatus shown in FIG. 4.

Hereinafter, the present invention will be described in detail.
In addition, in this specification, description of "xx-yy" represents the numerical range containing xx and yy. Further, “(component A) compound represented by formula (1)” or the like is also simply referred to as “component A” or the like.
“(Meth) acrylate” and the like are synonymous with “acrylate and / or methacrylate” and the like.
In the present invention, “mass%” and “wt%” are synonymous, and “part by mass” and “part by weight” are synonymous.
Hereinafter, the present invention will be described in detail.

(Inkjet ink composition)
The ink-jet ink composition of the present invention (hereinafter also simply referred to as “ink composition”) is composed of (Component A) a compound represented by Formula (1), (Component B) photopolymerization having a molecular weight of 400 to 2,000. An initiator and (Component C) a polyfunctional polymerizable compound other than Component A are contained, and the total content of Component A and Component C is 80 mass relative to the total mass of the polymerizable compound in the ink composition. % Or more.

（式（１）中、Ｒ¹はそれぞれ独立に、水素原子又はメチル基を表し、Ｌ¹はそれぞれ独立に、炭素原子数２〜４の直鎖又は分岐のアルキレン基を表し、また、Ｌ¹において、Ｌ¹の両端に結合する酸素原子と窒素原子とがＬ¹の同一の炭素原子に結合した構造をとることはなく、Ｌ²はそれぞれ独立に、２価の連結基を表し、ｋはそれぞれ独立に、２又は３を表し、ｘ、ｙ及びｚはそれぞれ独立に、０〜６の整数を表し、ｘ＋ｙ＋ｚは０〜１８を満たす。）

(In the formula (1), R ¹ each independently represent a hydrogen atom or a methyl group, L ¹ each independently represents a linear or branched alkylene group having 2 to 4 carbon atoms, also, L ¹ in not take an oxygen atom and a nitrogen atom bonded to both ends of the L ¹ is bonded to the same carbon atom of L ¹ structure, L ² each independently represents a divalent linking group, k is Each independently represents 2 or 3, x, y, and z each independently represent an integer of 0-6, and x + y + z satisfies 0-18.)

The ink composition of the present invention is an ink composition curable by actinic radiation. “Actinic radiation” is radiation that can give energy to generate an initial species in the ink composition by irradiation, and includes α rays, γ rays, X rays, ultraviolet rays, visible rays, electron rays, and the like. Of these, ultraviolet rays and electron beams are preferable from the viewpoint of curing sensitivity and device availability, and ultraviolet rays are more preferable.
The ink composition of the present invention is an actinic radiation curable ink composition, and is preferably an oil-based ink composition. The ink composition of the present invention preferably contains as little water and volatile solvent as possible, and even if it contains, it is preferably 5% by mass or less, and preferably 1% by mass with respect to the total mass of the ink composition. More preferably, it is more preferably 0.5% by mass or less.
Furthermore, the ink composition of the present invention can be suitably used as an inkjet ink composition for printing food packages.

Inkjet printing does not require a plate, and therefore can handle small lots compared to gravure printing that requires a plate. However, since inkjet printing is less productive than gravure printing, high productivity is required.
When printing on food packages is intended, the substrate is mainly a non-absorbable substrate such as polypropylene (PP). For this reason, when the water-based ink composition for ink jet is used, problems such as increase in drying time, image quality deterioration due to landing interference, and film quality deterioration such as peeling from the substrate may occur, and high production cannot be realized.
Further, since it takes time to dry the ink-jet solvent ink, it is difficult to increase the production.
An actinic radiation curable inkjet ink composition such as the inkjet ink composition of the present invention is exposed and photocured immediately after the ink discharged from the head has landed. For this reason, although high production is possible, use of a polymeric compound and a photoinitiator becomes essential.
When a conventional actinic radiation curable ink-jet ink composition is used, an odor may be generated due to a part of the polymerizable compound or photopolymerization initiator remaining after photocuring. For food packaging applications, in addition to odor, low molecular weight compounds are not required to be extracted and eluted (migration suitability).
When the present inventor conducted a detailed study on the prescription design corresponding to printing for food packaging, the composition of component A to component C and further containing many polyfunctional polymerizable compounds, the image obtained It has been found that an ink-jet ink composition having excellent bending resistance, little elution (migration) of components in the ink film after curing to the outside, and less stickiness and odor of the obtained image can be obtained.
Hereinafter, the ink-jet ink composition of the present invention will be described in detail.

(Component A) Compound Represented by Formula (1) The inkjet ink composition of the present invention contains (Component A) a compound represented by Formula (1).

（式（１）中、Ｒ¹はそれぞれ独立に、水素原子又はメチル基を表し、Ｌ¹はそれぞれ独立に、炭素原子数２〜４の直鎖又は分岐のアルキレン基を表し、また、Ｌ¹において、Ｌ¹の両端に結合する酸素原子と窒素原子とがＬ¹の同一の炭素原子に結合した構造をとることはなく、Ｌ²はそれぞれ独立に、２価の連結基を表し、ｋはそれぞれ独立に、２又は３を表し、ｘ、ｙ及びｚはそれぞれ独立に、０〜６の整数を表し、ｘ＋ｙ＋ｚは０〜１８を満たす。）

(In the formula (1), R ¹ each independently represent a hydrogen atom or a methyl group, L ¹ each independently represents a linear or branched alkylene group having 2 to 4 carbon atoms, also, L ¹ in not take an oxygen atom and a nitrogen atom bonded to both ends of the L ¹ is bonded to the same carbon atom of L ¹ structure, L ² each independently represents a divalent linking group, k is Each independently represents 2 or 3, x, y, and z each independently represent an integer of 0-6, and x + y + z satisfies 0-18.)

  Component A used in the present invention has four (meth) acrylamide groups as polymerizable groups in the molecule, and has high polymerization performance and curability. Further, by containing Component A, an inkjet ink composition having excellent bending resistance of the obtained image and less stickiness of the obtained image can be obtained.

Each R ¹ independently represents a hydrogen atom or a methyl group. Several R < ¹ > may mutually be same or different. R ¹ is preferably a hydrogen atom. Moreover, it is preferable that all R < ¹ > is the same group.

L ¹ each independently represents a linear or branched alkylene group having 2 to 4 carbon atoms. The plurality of L ¹ may be the same as or different from each other. The alkylene group of L ¹ is preferably 3 or 4, 3 is more preferable. L ¹ is particularly preferably a linear alkylene group having 3 carbon atoms. The alkylene group of L ¹ may further have a substituent, and examples of the substituent include an aryl group and an alkoxy group.
However, in L ^1, the oxygen atom and the nitrogen atom bonded to both ends of the L ¹ does not take a structure bound to the same carbon atom of L ^1. L ¹ is a linear or branched alkylene group linking an oxygen atom and a nitrogen atom of a (meth) acrylamide group. When the alkylene group has a branched structure, oxygen atoms at both ends and the nitrogen of the (meth) acrylamide group It is also conceivable to take an —O—C—N— structure (hemaminal structure) in which an atom is bonded to the same carbon atom in an alkylene group. However, the compound represented by the formula (1) used in the present invention does not include a compound having such a structure. When the molecule has an —O—C—N— structure, decomposition is likely to occur at the position of the carbon atom. In particular, such a compound is easily decomposed during storage, and the decomposition is accelerated in the presence of water and moisture, thereby reducing the storage stability of the cured composition.
Moreover, it is preferable that all L < ¹ > is the same group.

Examples of the divalent linking group for L ² include an alkylene group, an arylene group, a divalent heterocyclic group, or a group selected from the group consisting of a combination of two or more of these, and is an alkylene group. It is preferable. When the divalent linking group includes an alkylene group, the alkylene group further includes at least one group selected from the group consisting of —O—, —S—, and —N (Ra) —. It may be. Here, Ra represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms.
The term “-O— contained in the alkylene group” means that the alkylene group of the linking group of the linking group is linked via the heteroatom as in, for example, -alkylene-O-alkylene-.
Specific examples of the alkylene group containing —O— include —C ₂ H ₄ —O—C ₂ H ₄ —, —C ₃ H ₆ —O—C ₃ H ₆ — and the like.

When L ² contains an alkylene group, examples of the alkylene group include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, a hexylene group, a heptylene group, an octylene group, and a nonylene group. L number of carbon atoms in the alkylene group ^2, 6 is preferred, more preferably 1 to 3, 1 is particularly preferred. Further, this alkylene group may further have a substituent, and examples of the substituent include an aryl group and an alkoxy group.

When L ² contains an arylene group, examples of the arylene group include phenylene and naphthylene. 6-14 are preferable, as for carbon number of an arylene group, 6-10 are more preferable, and 6 is especially preferable. This arylene group may further have a substituent, and examples of the substituent include an alkyl group and an alkoxy group.

When L ² contains a divalent heterocyclic group, this heterocyclic ring is preferably a 5-membered ring or a 6-membered ring, and may be condensed. Further, it may be an aromatic heterocyclic ring or a non-aromatic heterocyclic ring. The heterocyclic ring of the divalent heterocyclic group includes pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline, isoquinoline, quinazoline, cinnoline, phthalazine, quinoxaline, pyrrole, indole, furan, benzofuran, thiophene, benzothiophene, pyrazole, imidazole, Examples include benzimidazole, triazole, oxazole, benzoxazole, thiazole, benzothiazole, isothiazole, benzisothiazole, thiadiazole, isoxazole, benzisoxazole, pyrrolidine, piperidine, piperazine, imidazolidine, thiazoline and the like. Among them, an aromatic heterocyclic ring is preferable, and pyridine, pyrazine, pyrimidine, pyridazine, triazine, pyrazole, imidazole, benzimidazole, triazole, thiazole, benzothiazole, isothiazole, benzisothiazole, and thiadiazole are preferable.

The position of the two bonds of the heterocycle of the divalent heterocyclic group is not particularly limited. For example, in the case of pyridine, substitution at the 2-position, 3-position, and 4-position is possible. The bond may be in any position.
Moreover, the heterocyclic ring of a bivalent heterocyclic group may further have a substituent, and examples of the substituent include an alkyl group, an aryl group, and an alkoxy group.
Further, we are preferable that all L ² are the same group.

Each k independently represents 2 or 3, but a plurality of k may be the same or different from each other. C _k H _2k may be a linear structure or a branched structure.

  x, y and z each independently represent an integer of 0 to 6, an integer of 0 to 5 is preferable, and an integer of 0 to 3 is more preferable. x + y + z satisfies 0 to 18, preferably 0 to 15, and more preferably 0 to 9.

  Specific examples of the compound represented by the formula (1) are shown below, but the present invention is not limited thereto.

  The compound represented by Formula (1) can be suitably manufactured according to the following scheme 1 or scheme 2, for example.

Scheme 1
(First step) A step of obtaining a polycyano compound by a reaction of acrylonitrile and trishydroxymethylaminomethane. The reaction in this step is preferably performed at 3 to 60 ° C. for 2 to 8 hours.
(Second step) A step of reacting a polycyano compound with hydrogen in the presence of a catalyst such as Raney nickel and obtaining a polyamine compound by a reduction reaction. The reaction in this step is preferably performed at 20 to 60 ° C. for 5 to 16 hours.
(Third step) A step of obtaining a polyfunctional acrylamide compound by an acylation reaction between a polyamine compound and acrylic acid chloride or methacrylic acid chloride. The reaction in this step is preferably performed at 3 to 25 ° C. for 1 to 5 hours. The acylating agent may be diacrylic anhydride or dimethacrylic anhydride instead of acid chloride. In addition, by using both acrylic acid chloride and methacrylic acid chloride in the acylation step, a compound having an acrylamide group and a methacrylamide group in the same molecule can be obtained as the final product.

Scheme 2
(First step) A step of obtaining a nitrogen-protected aminoalcohol compound by a protective group introduction reaction with a benzyl group (Bz in the above scheme), a benzyloxycarbonyl group or the like on the nitrogen atom of the aminoalcohol. The reaction in this step is preferably performed at 3 to 25 ° C. for 3 to 5 hours.
(2nd process) The process of introduce | transducing leaving groups, such as a methanesulfonyl group and p-toluenesulfonyl group, into OH group of a nitrogen protection amino alcohol compound, and obtaining a sulfonyl compound. The reaction in this step is preferably performed at 3 to 25 ° C. for 2 to 5 hours. MsCl represents methanesulfonyl chloride.
(Third step) A step of obtaining an amino alcohol addition compound by S _N 2 reaction between a sulfonyl compound and trishydroxymethylnitromethane. The reaction in this step is preferably performed at 3 to 70 ° C. for 5 to 10 hours.
(Fourth step) A step of reacting an amino alcohol addition compound with hydrogen in the presence of a catalyst such as palladium carbon (Pd / C) to obtain a polyamine compound by hydrogenation reaction. The reaction in this step is preferably performed at 20 to 60 ° C. for 5 to 16 hours.
(Fifth step) A step of obtaining a polyfunctional acrylamide compound by an acylation reaction between a polyamine compound and acrylic acid chloride or methacrylic acid chloride. The reaction in this step is preferably performed at 3 to 25 ° C. for 1 to 5 hours. The acylating agent may be diacrylic anhydride or dimethacrylic anhydride instead of acid chloride. In addition, by using both acrylic acid chloride and methacrylic acid chloride in the acylation step, a compound having an acrylamide group and a methacrylamide group in the same molecule can be obtained as the final product.

  The compound obtained by the above steps can be purified from the reaction product solution by a conventional method. For example, it can be purified by liquid separation extraction using an organic solvent, crystallization using a poor solvent, column chromatography using silica gel, and the like.

  In the ink composition of the present invention, two or more compounds represented by the formula (1) may be used in combination.

The compound represented by the formula (1) used in the present invention has four (meth) acrylamide groups, has high polymerization ability, and can impart excellent curability to the cured composition. Therefore, in the ink composition of the present invention, the formed image is quickly cured and fixed. As a result, it is possible to prevent show-through during printing and improve the printing speed.
In addition, the compound represented by the formula (1) used in the present invention is a compound in which three oxygen atoms derived from a hydroxyl group of a raw material polyol and a (meth) acrylamide group are bonded to the same carbon atom. Since it does not take a structure (that is, an oxygen atom and a (meth) acrylamide group are not linked via a methylene group), hydrolysis of the compound can be suppressed. As a result, it is considered that the storage stability of the ink composition of the present invention is improved.

The molecular weight of component A is preferably less than 1,500, and more preferably less than 1,000.
The content of Component A is preferably 0.1 to 45% by mass, more preferably 1 to 20% by mass, and 2 to 15% by mass with respect to the total mass of the ink composition. Further preferred. Within the above range, an ink composition in which the amount of elution (migration) of the components in the ink film after curing to the outside is smaller and the resulting image has less stickiness and odor can be obtained.

(Component B) Photopolymerization initiator having a molecular weight of 400 or more and 2,000 or less The inkjet ink composition of the present invention contains (Component B) a photopolymerization initiator having a molecular weight of 400 or more and 2,000 or less. By containing the component B, an ink-jet ink composition can be obtained in which the amount of elution (migration) to the outside of the components in the ink film after curing is small and the resulting image has little odor.
Component B preferably contains at least a photopolymerization initiator having a molecular weight of 500 or more and 2,000 or less, and more preferably contains at least a photopolymerization initiator having a molecular weight of 600 or more and 2,000 or less. In the above-described aspect, an ink-jet ink composition can be obtained in which the amount of elution of the components in the ink film after curing to the outside is smaller and the resulting image has less odor.

As the component B, a known photopolymerization initiator can be used as long as it has a molecular weight of 400 or more and 2,000 or less.
Moreover, the component B may be used individually by 1 type, and may use 2 or more types together.
Component B is a photopolymerization initiator and is a compound that absorbs actinic radiation (light) and generates a polymerization initiating species. Examples of the active radiation include γ rays, β rays, electron beams, ultraviolet rays, visible rays, and infrared rays.
Moreover, the inkjet ink composition of this invention should just contain the component B at least, and may further contain the photoinitiator with a molecular weight of less than 400, and the photoinitiator with a molecular weight of more than 2,000.

The photopolymerization initiator that can be used in the present invention is preferably a photoradical polymerization initiator.
Examples of the radical photopolymerization initiator that can be used in the present invention include (a) aromatic ketones, (b) acylphosphine compounds, (c) aromatic onium salt compounds, (d) organic peroxides, (e) Thio compound, (f) hexaarylbiimidazole compound, (g) ketoxime ester compound, (h) borate compound, (i) azinium compound, (j) metallocene compound, (k) active ester compound, (l) carbon halogen Examples thereof include a compound having a bond and (m) an alkylamine compound. These radical photopolymerization initiators may be used alone or in combination with the above compounds (a) to (m). Further, for example, a plurality of types from (a) can be used in combination.
Among these, the component B is preferably a compound selected from the group consisting of an α-hydroxyketone compound, a hexaarylbiimidazole compound, a thioxanthone compound, and an α-aminoketone compound, and more preferably an α-hydroxyketone compound. A compound having two or more α-hydroxyketone structures is more preferable. In the above embodiment, particularly excellent in surface curability, and by increasing the conversion rate of the polymerizable compound by actinic ray irradiation and improving the molecular weight of the cured product in the cured film, the amount of elution of components in the film to the outside Is obtained, the odor of the printed matter is further suppressed, and an inkjet ink composition having excellent blocking resistance is obtained.

The number of α-hydroxyketone structures in the compound having two or more α-hydroxyketone structures may be two or more, preferably 2 to 10, more preferably 2 to 7, 2 to 5 is particularly preferable.
In addition, the α-hydroxyketone structure in the compound having two or more α-hydroxyketone structures is preferably an α-hydroxyacetophenone structure, and a 2-hydroxy-2-methyl-1-phenylpropan-1-one structure. It is particularly preferred that
Specific examples of the compound having two or more α-hydroxyketone structures preferably include the following HK-1.

（式中、ｎは２以上の整数を表し、Ｒは末端基を表す。）

(In the formula, n represents an integer of 2 or more, and R represents a terminal group.)

n is preferably an integer of 2 to 10, more preferably an integer of 2 to 7, and still more preferably an integer of 2 to 5.
R is not particularly limited, and examples thereof include a hydrogen atom, an alkyl group, an alkoxy group, a hydroxy group, and a halogen atom.

  In addition, as Component B, 2,2′-bis (2-chlorophenyl) -4,4 ′, 5,5′-tetraphenyl-1,2′-biimidazole (“SPEDCURE BCIM” manufactured by Rambson), oligo {2-Hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone} (“ESACURE KIP150” manufactured by Lamberti, corresponding to the above HK-1), 1,3-di ({ α-2- (phenylcarbonyl) benzoylpoly [oxy (1-methylethylene)]} oxy) -2,2-bis ({α-2- (phenylcarbonyl) benzoylpoly [oxy (1-methylethylene)]} Oxymethyl) propane (included in “SPEEDCURE 7005” manufactured by Rambson), {α-2- (phenylcarbonyl) benzoylpo (Oxyethylene) -poly [oxy (1-methylethylene)]-poly (oxyethylene)} 2- (phenylcarbonyl) benzoate (included in "SPEEDCURE 7005" manufactured by Lambson), 1,3-di ({ α- [1-Chloro-9-oxo-9H-thioxanthen-4-yl] oxy} acetylpoly [oxy (1-methylethylene)]) oxy) -2,2-bis ({α- [1-chloro -9-oxo-9H-thioxanthen-4-yl] oxy} acetylpoly [oxy (1-methylethylene)]) oxymethylpropane ("SPEEDCURE 7010" manufactured by Rambson), 1,3-di ({α- 4- (Dimethylamino) benzoylpoly [oxy (1-methylethylene)]} oxy) -2,2-bis ({α-4- (dimethylamino) Nzoyl poly [oxy (1-methylethylene)]} oxymethyl) propane (included in “SPEEDCURE 7040” manufactured by Lambson) and {α-4- (dimethylamino) benzoyl poly (oxyethylene) -poly [oxy At least one photopolymerization initiator selected from the group consisting of (1-methylethylene)]-poly (oxyethylene)} 4- (dimethylamino) benzoate (included in “SPEEDCURE 7040” manufactured by Lambson) It is preferable to include. In the case of the above-described aspect, an ink-jet ink composition is obtained in which the amount of elution (migration) to the outside of the components in the ink film after curing is smaller, and the resulting image has less odor.

  In addition to the above, the photopolymerization initiators other than Component B and Component B that can be used in the present invention are exemplified below.

  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 and α-aminobenzophenone 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 (MW (molecular weight): 182.2), 4-phenylbenzophenone (MW: 258), isophthalophenone (MW: 286), 4 ′, 4 ″ -diethylisophthalophenone (MW: 342). ), 4-benzoyl-4′-methyldiphenyl sulfide (MW: 304), etc. The thioxanthone compound is 2,4-diethylthioxanthone (MW: 268), 2-isopropylthioxanthone (MW: 254). And 2-chlorothioxanthone (MW: 248).

  In addition, (a) aromatic ketones are preferably α-hydroxyketone compounds (including α-hydroxyalkylphenone compounds), α-aminoketone compounds (including α-aminoalkylphenone compounds), and ketal compounds. Specifically, 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl] phenyl} -2-methyl-propan-1-one (MW 340.4), 2 -Methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one (MW279.4), 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone- 1 (MW 366.5), 2,2-dimethoxy-1,2-diphenylethane-1-one (MW 256.3), 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl -1-propan-1-one (IRGACURE 2959, MW: 224.3), 2-hydroxy-2-methyl-1-phenylpropan-1-one (DAROCURE 117) , MW: 164), 1- hydroxycyclohexyl phenyl ketone (MW: 204), 2,2- dimethoxy-1,2-diphenylethane can be exemplified.

Further, as the (b) acylphosphine compound, an acylphosphine oxide compound is preferable.
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 JP-B-60-8047 and JP-B63-40799.
Specific examples include isobutyrylmethylphosphinic acid methyl ester (MW: 164.1), isobutyrylphenylphosphinic acid methyl ester (MW: 226.2), and pivaloylphenylphosphinic acid methyl ester (MW: 240. 2), 2-ethylhexanoylphenylphosphinic acid methyl ester (MW: 270.3), pivaloylphenylphosphinic acid isopropyl ester (MW: 268.3), p-toluylphenylphosphinic acid methyl ester (MW: 274. 3), o-toluylphenylphosphinic acid methyl ester (MW: 274.3), 2,4-dimethylbenzoylphenylphosphinic acid methyl ester (MW: 288.3), pt-butylbenzoylphenylphosphinic acid isopropyl ester ( MW: 344.4 , Acryloylphenylphosphinic acid methyl ester (MW: 210.2), isobutyryl diphenylphosphine oxide (MW: 272.3), 2-ethylhexanoyldiphenylphosphine oxide (MW: 328.4), o-toluyldiphenylphosphine Oxide (MW: 320.3), p-t-butylbenzoyl diphenylphosphine oxide (MW: 350.4), 3-pyridylcarbonyldiphenylphosphine oxide (MW: 307.3), acryloyl-diphenylphosphine oxide (MW: 256) .2), benzoyldiphenylphosphine oxide (MW: 306.3), pivaloylphenylphosphinic acid vinyl ester (MW: 236.3), adipoylbisdiphenylphosphine oxide (M 514.5), pivaloyldiphenylphosphine oxide (MW: 286.3), p-toluyldiphenylphosphine oxide (MW: 320.3), 4- (t-butyl) benzoyldiphenylphosphine oxide (MW: 362. 4), terephthaloylbisdiphenylphosphine oxide (MW: 534.5), 2-methylbenzoyldiphenylphosphine oxide (MW: 320.3), 2-methyl-2-ethylhexanoyldiphenylphosphine oxide (MW: 342. 4), 1-methyl-cyclohexanoyl diphenylphosphine oxide (MW: 326.4), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (MW: 348.4), and the like.

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 (MW: 472.1), bis (2,6-dichlorobenzoyl) -2,5-dimethylphenylphosphine oxide (MW: 500.1). Bis (2,6-dichlorobenzoyl) -4-ethoxyphenylphosphine oxide (MW: 516.1), bis (2,6-dichlorobenzoyl) -4-propylphenylphosphine oxide (MW: 514.2), bis (2,6-dichlorobenzoyl) -2-naphthylphosphine oxide (MW: 522.2), bis (2,6-dichlorobenzoyl) -1-naphthylphosphine oxide (MW: 522.2), bis (2,6 -Dichlorobenzoyl) -4-chlorophenylphosphine oxide (MW: 506) 5), bis (2,6-dichlorobenzoyl) -2,4-dimethoxyphenylphosphine oxide (MW: 532.1), bis (2,6-dichlorobenzoyl) decylphosphine oxide (MW: 536.3), bis (2,6-dichlorobenzoyl) -4-octylphenylphosphine oxide (MW: 584.3), bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide (MW: 418.5), bis (2,4 , 6-Trimethylbenzoyl) -2,5-dimethylphenylphosphine oxide (MW: 446.5), bis (2,6-dichloro3,4,5-trimethoxybenzoyl) -2,5-dimethylphenylphosphine oxide ( MW: 632.3), bis (2,6-dichloro-3,4,5-trimethoxybe) Zoyl) -4-ethoxyphenylphosphine oxide (MW: 696.3), bis (2-methyl-1-naphthoyl) -2,5-dimethylphenylphosphine oxide (MW: 490.5), bis (2-methyl-) 1-naphthoyl) -4-ethoxyphenylphosphine oxide (MW: 506.5), bis (2-methyl-1-naphthoyl) -2-naphthylphosphine oxide (MW: 512.5), bis (2-methyl-1) -Naphthoyl) -4-propylphenylphosphine oxide (MW: 504.6), bis (2-methyl-1-naphthoyl) -2,5-dimethylphenylphosphine oxide (MW: 490.5), bis (2-methoxy) -1-naphthoyl) -4-ethoxyphenylphosphine oxide (MW: 506.5), bis (2-Chloro-1-naphthoyl) -2,5-dimethylphenylphosphine oxide (MW: 531.4), bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide (MW: 426) .5) and the like.

  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, MW: 418.5), bis (2 , 6-Dimethoxybenzoyl) -2,4,4-trimethylpentylphenylphosphine oxide (MW: 426.5), 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Darocur TPO: manufactured by Ciba Specialty Chemicals, Lucirin TPO) : BASF, MW: 348.4) is 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, European Patent No. 104143, US Pat. No. 4,837,124, JP-A-2-150848, JP-A-2-96514, iodonium salts, European Patent Nos. 370693 and 233567, In the specifications of U.S. Pat. Nos. 297443, 297442, 279210, and 422570, U.S. Pat. Nos. 3,902,144, 4,933,377, 4760013, 4,734,444, and 2,833,827. Described diazonium salts (such as benzenediazonium optionally having substituents), diazonium salt resins (such as formaldehyde resin of diazodiphenylamine), N-alkoxypyridinium salts and the like (for example, US Pat. No. 4,743,528) Description, JP-A-63-138345 JP-A-63-142345, JP-A-63-142346, and JP-B-46-42363, specifically 1-methoxy-4-phenylpyridinium tetrafluoro And the compounds described in JP-B Nos. 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 (MW: 646.7), 3,3 ', 4,4'-tetra (t-amylperoxycarbonyl) benzophenone (MW: 702.8), 3,3', 4 4′-tetra (t-hexylperoxycarbonyl) benzophenone (MW: 758.9), 3,3 ′, 4,4′-tetra (t-octylperoxycarbonyl) benzophenone (MW: 823.1), 3 , 3 ′, 4,4′-tetra (cumylperoxycarbonyl) benzophenone (MW: 895.0), 3,3 ′, 4,4′-tetra (p-isopropylcumylperoxycarbohydrate) Le) benzophenone (MW: 1063.3), di -t- butyl diperoxyisophthalate (MW: 310.3) Compound peroxide ester such is preferred.

  (F) Examples of hexaarylbiimidazole compounds include lophine dimers described in JP-B-45-37377 and JP-B-44-86516, such as 2,2′-bis (o-bromophenyl) -4,4. ', 5,5'-tetraphenylbiimidazole (MW: 748.5), 2,2'-bis (o, p-dichlorophenyl) -4,4', 5,5'-tetraphenylbiimidazole (MW: 732.5), 2,2′-bis (o-chlorophenyl) -4,4 ′, 5,5′-tetra (m-methoxyphenyl) biimidazole (MW: 779.7), 2,2′-bis (O, o′-dichlorophenyl) -4,4 ′, 5,5′-tetraphenylbiimidazole (MW: 728.5), 2,2′-bis (o-nitrophenyl) -4,4 ′, 5 , 5'-Tet Biimidazole (MW: 648.7), 2,2'-bis (o-methylphenyl) -4,4 ', 5,5' (MW: 618.8), and the like.

  (G) Examples of the ketoxime ester compound include 3-benzoyloxyiminobutan-2-one (MW: 205.2), 3-acetoxyiminobutan-2-one (MW: 143.1), and 3-propionyloxy. Iminobutan-2-one (MW: 157.2), 2-acetoxyiminopentan-3-one (MW: 157.2), 2-acetoxyimino-1-phenylpropan-1-one (MW: 205.2) ), 2-benzoyloxyimino-1-phenylpropan-1-one (MW: 267.3), 3-p-toluenesulfonyloxyiminobutan-2-one (MW: 255.3), 2-ethoxycarbonyl And oxyimino-1-phenylpropan-1-one (MW: 235.2).

  (H) Examples of borate compounds are described in US Pat. Nos. 3,567,453, 4,343,891, European Patents 109,772, and 109,773. Compounds.

  (I) Examples of azinium compounds include those disclosed in 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 compounds, and iron-arene complexes described in JP-A-1-304453 and JP-A-1-152109.

  Specific examples of the titanocene compound include di-cyclopentadienyl-Ti-di-chloride (MW: 249.0), di-cyclopentadienyl-Ti-bis-phenyl (MW: 332.3), di- -Cyclopentadienyl-Ti-bis-2,3,4,5,6-pentafluorophen-1-yl (MW: 512.2), di-cyclopentadienyl-Ti-bis-2,3 5,6-tetrafluorophen-1-yl (MW: 476.2), di-cyclopentadienyl-Ti-bis-2,4,6-trifluorophen-1-yl (MW: 440.2) , Di-cyclopentadienyl-Ti-2,6-difluorophen-1-yl (MW: 404.2), di-cyclopentadienyl-Ti-bis-2,4-difluorophen-1-yl ( MW: 404. ), Di-methylcyclopentadienyl-Ti-bis-2,3,4,5,6-pentafluorophen-1-yl (MW: 534.2), di-methylcyclopentadienyl-Ti-bis -2,3,5,6-tetrafluorophen-1-yl (MW: 498.2), di-methylcyclopentadienyl-Ti-bis-2,4-difluorophen-1-yl (MW: 426) .2), bis (cyclopentadienyl) -bis (2,6-difluoro-3- (pyridin-1-yl) phenyl) titanium (MW: 534.4), bis (cyclopentadienyl) bis [2 , 6-difluoro-3- (methylsulfonamido) phenyl] titanium (MW: 614.5).

  (K) Examples of the active ester compound include the specifications of European Patent Nos. 0290750, 046083, 156153, 271851, and 0388343, U.S. Pat. Nos. 3,901,710, and 4,181,531. Nitrobenzester compounds described in the specification, JP-A-60-198538 and JP-A-53-133022, European Patent Nos. 0199672, 84515, 199672, 0441115, And specifications of U.S. Pat. No. 4,101,564, U.S. Pat. Nos. 4,618,564, 4,371,605, and 4,431,774, JP-A 64-18143, JP-A 2-245756, and JP-A 4-245756 No. 3,650,481, an iminosulfonate compound described in JP-B-62-2223 , JP-B-63-14340, and compounds, and the like described in the JP-A No. 59-174831.

  (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) by FC Schaefer et al., Compounds described in JP-A-62-258241, compounds described in JP-A-5-281728, and the like can be mentioned. it can. A compound as described in German Patent No. 2641100, a compound described in German Patent No. 3333450, a group of compounds described in German Patent No. 3021590, or a German group A compound group described in Japanese Patent No. 3021599 can be exemplified.

The content of component B is preferably 0.1 to 20% by mass, more preferably 1 to 15% by mass, and more preferably 2 to 10% by mass with respect to the total mass of the ink composition. Is more preferable. In the above-described aspect, an ink-jet ink composition can be obtained in which the amount of elution of the components in the ink film after curing to the outside is smaller and the resulting image has less odor.
In addition, the content of the photopolymerization initiator other than Component B is preferably less than the content of Component B and more preferably less than ½ of the content of Component B in terms of mass ratio. In the above embodiment, an ink-jet ink composition is obtained that is superior in the bending resistance of the obtained image, has a smaller amount of elution of components in the ink film after curing to the outside, and has less stickiness and odor of the obtained image. .

The ink composition of the present invention, as a photopolymerization initiator, absorbs specific actinic radiation and accelerates the decomposition of the polymerization initiator, and therefore functions as a sensitizer (hereinafter also referred to simply as “sensitizer”). .) May be contained.
The sensitizer absorbs specific actinic radiation and enters an electronically excited state. The sensitizer in an electronically excited state comes into contact with the polymerization initiator, and effects such as electron transfer, energy transfer, and heat generation occur. As a result, the photopolymerization initiator containing component B undergoes a chemical change and decomposes to generate a polymerization initiating species such as a radical, acid, or base.
As a sensitizer that can be used in the present invention, a sensitizing dye is preferable.
Examples of preferred sensitizing dyes include those belonging to the following compounds and having an absorption wavelength in the 350 nm to 450 nm region.
Polynuclear aromatics (eg, pyrene, perylene, triphenylene), xanthenes (eg, fluorescein, eosin, erythrosine, rhodamine B, rose bengal), cyanines (eg, thiacarbocyanine, oxacarbocyanine), merocyanines (For example, merocyanine, carbomerocyanine), thiazines (for example, thionine, methylene blue, toluidine blue), acridines (for example, acridine orange, chloroflavin, acriflavine), anthraquinones (for example, anthraquinone), squalium (for example, Squalium), coumarins (for example, 7-diethylamino-4-methylcoumarin), thioxanthones (for example, thioxanthone, isopropylthioxanthone, diethylthioxanthone).
Among these, thioxanthones are preferable.
Moreover, as a sensitizing dye, what was described in Paragraphs 0091-0104 of Unexamined-Japanese-Patent No. 2011-32348 can be illustrated.

A sensitizer may be used individually by 1 type and may use 2 or more types together.
The content of the 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 mass with respect to the total mass of the ink composition.

(Component C) Polyfunctional polymerizable compound other than Component A The inkjet ink composition of the present invention comprises (Component C) a polyfunctional polymerizable compound other than Component A, and the total content of Component A and Component C is It is 80 mass% or more with respect to the total mass of the polymerizable compound in the ink composition. In the above embodiment, an ink-jet ink composition can be obtained in which the amount of elution of the components in the ink film after curing is small and the resulting image has little odor.
The total content of Component A and Component C is 80% by mass or more, preferably 90% by mass or more, and more preferably 95% by mass with respect to the total mass of the polymerizable compound in the ink composition. Preferably, it is 98 mass% or more, and it is especially preferable that it is 100 mass%. In the above-described aspect, an ink-jet ink composition can be obtained in which the amount of elution of the components in the ink film after curing to the outside is smaller and the resulting image has less odor.

Component C is not particularly limited as long as it is a polyfunctional polymerizable compound other than component A, but is preferably a bifunctional to tetrafunctional polymerizable compound, and is preferably a bifunctional or trifunctional polymerizable compound. More preferred. In the above embodiment, an ink-jet ink composition is obtained that is superior in the bending resistance of the obtained image and has less stickiness of the obtained image.
Component C is preferably a polyfunctional radically polymerizable compound, more preferably a polyfunctional ethylenically unsaturated compound, still more preferably a polyfunctional (meth) acrylate compound, and a polyfunctional acrylate compound. It is particularly preferred. In the above embodiment, an ink-jet ink composition is obtained that is superior in the bending resistance of the obtained image and has less stickiness of the obtained image.
In this specification, “(meth) acrylate” and “(meth) acrylate” and “acrylic” and “methacryl” are used when referring to “acrylate” and / or “methacrylate”. And may be described respectively.

  Examples of the bifunctional (meth) acrylate compound include 3-methyl-1,5-pentanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, and 1,10-decanediol di (meta). ) Acrylate, 1,12-dodecanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 2,4-dimethyl-1,5-pentanediol di (meth) acrylate, butylethylpropanediol (meth) acrylate , Ethoxylated cyclohexanemethanol di (meth) acrylate, polyethylene glycol di (meth) acrylate, oligoethylene glycol di (meth) acrylate, ethylene glycol di (meth) acrylate, 2-ethyl-2-butylbutanediol di (meth) acrylate Hydroxypivalate neopentyl glycol di (meth) acrylate, ethylene oxide (EO) modified bisphenol A di (meth) acrylate, bisphenol F polyethoxydi (meth) acrylate, polypropylene glycol di (meth) acrylate, oligopropylene glycol di ( (Meth) acrylate, 1,4-butanediol di (meth) acrylate, 2-ethyl-2-butylpropanediol di (meth) acrylate, 1,9-nonanedi (meth) acrylate, propoxylated ethoxylated bisphenol A di (meth) ) Acrylate, tricyclodecane di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, propylene oxide (PO) modification Neopentyl glycol di (meth) acrylate.

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

Examples of the tetrafunctional (meth) acrylate include pentaerythritol tetra (meth) acrylate, sorbitol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate propionate, and ethoxylated penta Examples include erythritol tetra (meth) acrylate.
Examples of pentafunctional (meth) acrylates include sorbitol penta (meth) acrylate and dipentaerythritol penta (meth) acrylate.
Examples of hexafunctional (meth) acrylates include dipentaerythritol hexa (meth) acrylate, sorbitol hexa (meth) acrylate, phosphazene alkylene oxide-modified hexa (meth) acrylate, and ε-captolactone-modified dipentaerythritol hexa (meth). ) Acrylate and the like.

  More specifically, Shinzo Yamashita “Cross-linking agent handbook” (1981, Taiseisha); Kato Kiyosumi “UV / EB curing handbook (raw material)” (1985, Polymer publication society); Ed. “Application and Market of UV / EB Curing Technology” on page 79 (1989, CMC Publishing Co., Ltd.); “Polyester Resin Handbook” by Eiichiro Takiyama (1988, Nikkan Kogyo Shimbun) Polyfunctional polymerizable compounds known in the industry can be used.

The inkjet ink composition of the present invention comprises, as Component C, a group consisting of dodecanediol diacrylate, 3-methyl-1,5-pentanediol diacrylate, trimethylolpropane triacrylate, and ethylene oxide-modified trimethylolpropane triacrylate. It is preferable that at least 1 type of compound chosen from is included. In the above-described aspect, an ink-jet ink composition can be obtained in which the amount of elution of the components in the ink film after curing to the outside is smaller and the resulting image has less odor.
The ink-jet ink composition of the present invention has a total content of dodecanediol diacrylate, 3-methyl-1,5-pentanediol diacrylate, trimethylolpropane triacrylate, and ethylene oxide-modified trimethylolpropane triacrylate. The amount of the component C in the ink composition is preferably 80% by mass or more, more preferably 85% by mass or more, and still more preferably 90% by mass or more. In the above embodiment, an ink jet ink composition is obtained that is superior in the bending resistance of the obtained image, has a smaller amount of elution of components in the ink film after curing to the outside, and has a less odor in the obtained image.

Component C may be contained singly or in combination of two or more.
The content of Component C is preferably 50 to 95% by mass, more preferably 55 to 92% by mass, and still more preferably 65 to 92% by mass with respect to the total mass of the ink composition from the viewpoint of curability. 75 to 92% by mass is particularly preferable. In the above aspect, an ink-jet ink composition can be obtained in which the amount of components in the ink film after curing is less elution to the outside and the resulting image has less stickiness and odor.

<Monofunctional polymerizable compound>
The ink composition of the present invention may contain a monofunctional polymerizable compound.
The ink composition of the present invention preferably contains no monofunctional polymerizable compound or the content of the monofunctional polymerizable compound is preferably 15% by mass or less based on the total mass of the ink composition. It does not contain a functional polymerizable compound, or the content of the monofunctional polymerizable compound is more preferably 10% by mass or less with respect to the total mass of the ink composition, and does not contain a monofunctional polymerizable compound Alternatively, the content of the monofunctional polymerizable compound is more preferably 5% by mass or less with respect to the total mass of the ink composition, and it is particularly preferable that no monofunctional polymerizable compound is contained. In the above embodiment, an ink jet ink composition is obtained that is superior in the bending resistance of the obtained image, has a smaller amount of elution of components in the ink film after curing to the outside, and has a less odor in the obtained image.
The monofunctional polymerizable compound is preferably a monofunctional radical polymerizable compound, more preferably a monofunctional ethylenically unsaturated compound, and even more preferably a monofunctional (meth) acrylate compound.
A monofunctional polymerizable compound may not be used, may be used individually by 1 type, and may use 2 or more types together.

  Examples of monofunctional (meth) acrylate compounds include hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, tert-octyl (meth) acrylate, isoamyl (meth) acrylate, decyl (meth) acrylate, and isodecyl (meth). Acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, 4-n-butylcyclohexyl (meth) acrylate, bornyl (meth) acrylate, isobornyl (meth) acrylate, benzyl (meth) acrylate, 2-ethylhexyl diglycol (meth) acrylate, butoxyethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 4-bromobutyl (meth) acrylate, Noethyl (meth) acrylate, benzyl (meth) acrylate, butoxymethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, 2- (2-methoxyethoxy) ethyl (meth) acrylate, 2- (2-butoxyethoxy) Ethyl (meth) acrylate, 2,2,2-tetrafluoroethyl (meth) acrylate, 1H, 1H, 2H, 2H-perfluorodecyl (meth) acrylate, 4-butylphenyl (meth) acrylate, phenyl (meth) acrylate 2,4,5-tetramethylphenyl (meth) acrylate, 4-chlorophenyl (meth) acrylate, phenoxymethyl (meth) acrylate, phenoxyethyl (meth) acrylate, glycidyl (meth) acrylate, glycidyloxybutyl (meta Acrylate, glycidyloxyethyl (meth) acrylate, glycidyloxypropyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxypropyl (Meth) acrylate, 2-hydroxybutyl (meth) acrylate,

4-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylate, diethylaminopropyl (meth) acrylate, trimethoxy Silylpropyl (meth) acrylate, trimethylsilylpropyl (meth) acrylate, polyethylene oxide monomethyl ether (meth) acrylate, oligoethylene oxide monomethyl ether (meth) acrylate, polyethylene oxide (meth) acrylate, oligoethylene oxide (meth) acrylate, oligoethylene oxide monoalkyl Ether (meth) acrylate, polyethylene oxide monoalkyl ether ) Acrylate, dipropylene glycol (meth) acrylate, polypropylene oxide monoalkyl ether (meth) acrylate, oligopropylene oxide monoalkyl ether (meth) acrylate, 2-methacryloyloxytyl succinic acid, 2-methacryloyloxyhexahydrophthalic acid 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, butoxydiethylene glycol (meth) acrylate, trifluoroethyl (meth) acrylate, perfluorooctylethyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate , Ethylene oxide (EO) modified phenol (meth) acrylate, EO modified cresol (meth) acrylate, EO modified nonylphenol (meta Acrylate, propylene oxide (PO) modified nonylphenol (meth) acrylate, EO modified-2-ethylhexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyl (meth) Examples include acrylate, (3-ethyl-3-oxetanylmethyl) (meth) acrylate, phenoxyethylene glycol (meth) acrylate, and cyclic trimethylolpropane formal acrylate.

  Examples of the monofunctional (meth) acrylamide compound include (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-propyl (meth) acrylamide, and Nn-butyl (meth) acrylamide. N-t-butyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-methylol (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N- Examples include diethyl (meth) acrylamide and (meth) acryloylmorpholine.

  Examples of monofunctional aromatic vinyl compounds include styrene, dimethyl styrene, trimethyl styrene, isopropyl styrene, chloromethyl styrene, methoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, bromo styrene, vinyl benzoic acid methyl ester, and 3-methyl. Styrene, 4-methylstyrene, 3-ethylstyrene, 4-ethylstyrene, 3-propylstyrene, 4-propylstyrene, 3-butylstyrene, 4-butylstyrene, 3-hexylstyrene, 4-hexylstyrene, 3-octyl Styrene, 4-octylstyrene, 3- (2-ethylhexyl) styrene, 4- (2-ethylhexyl) styrene, allyl styrene, isopropenyl styrene, butenyl styrene, octenyl styrene, 4-t-but Aryloxycarbonyl styrene include 4-t-butoxystyrene.

  Furthermore, as monofunctional polymerizable compounds, for example, vinyl esters (such as vinyl acetate, vinyl propionate, vinyl versatate), allyl esters (such as allyl acetate), halogen-containing monomers (vinylidene chloride, vinyl chloride, etc.) ), Vinyl ether (methyl vinyl ether, butyl vinyl ether, hexyl vinyl ether, methoxy vinyl ether, 2-ethylhexyl vinyl ether, methoxyethyl vinyl ether, cyclohexyl vinyl ether, chloroethyl vinyl ether, triethylene glycol divinyl ether, etc.), vinyl cyanide ((meth) acrylonitrile, etc.) Olefins (ethylene, propylene, etc.), N-vinyllactams (N-vinylcaprolactam, etc.) and the like.

<Polymerization inhibitor>
The ink composition of the present invention preferably contains a polymerization inhibitor.
As the polymerization inhibitor, known polymerization inhibitors can be used, and examples thereof include phenols, quinones, nitro compounds, nitroso compounds, amines, and sulfides.
Further, as the polymerization inhibitor, a radical polymerization inhibitor is preferable.
As a polymerization inhibitor, hydroquinone monomethyl ether, TEMPO (2,2,6,6-tetramethylpiperidinyl 1-oxyl), OH-TEMPO (4-hydroxy-2,2,6,6-tetramethylpiperidine 1 -Oxyl) and cuperone Al (tris (N-nitroso-N-phenylhydroxyamine) aluminum salt) are preferred.
Other polymerization inhibitors include hydroquinone, mono-tert-butylhydroquinone, catechol, p-tert-butylcatechol, p-methoxyphenol, p-tert-butylcatechol, 2,6-di-tert-butyl. -M-cresol, pyrogallol, β-naphthol, phenols such as 4-methoxy-1-naphthol, quinones such as benzoquinone, 2,5-diphenyl-p-benzoquinone, p-toluquinone, p-xyloquinone; nitrobenzene, m Nitro compounds or nitroso compounds such as dinitrobenzene, 2-methyl-2-nitrosopropane, α-phenyl-tert-butylnitrone, 5,5-dimethyl-1-pyrroline-1-oxide; chloranilamine, diphenylamine, diphenylpicryl Ruhydrazine And radical polymerization inhibitors such as amines such as phenol-α-naphthylamine, pyridine and phenothiazine; sulfides such as dithiobenzoyl sulfide and dibenzyl tetrasulfide. In addition, hindered amine compounds can also be exemplified.
Among these, as the polymerization inhibitor, TEMPO or OH-TEMPO is preferable, and OH-TEMPO is particularly preferable. In the case of the above aspect, the storage stability is excellent even when the inkjet ink composition is stored in the ink pack.

A polymerization inhibitor may be used individually by 1 type, and may use 2 or more types together.
The content of the polymerization inhibitor in the ink composition of the present invention is preferably 0.01 to 5% by mass and more preferably 0.01 to 1% by mass with respect to the total mass of the ink composition. More preferably, the content is 0.01 to 0.5% by mass. It is excellent in surface curability, adhesiveness, image quality, and blocking resistance as it is the said range.

<Oligomer>
The ink composition preferably contains an oligomer.
The “oligomer” is a polymer having structural units generally based on a finite number of monomers (generally 5 to 100). The weight average molecular weight of the oligomer is preferably 1,500 to 10,000, and more preferably 1,500 to 5,000.
In addition, the weight average molecular weight and the number average molecular weight of the compound in the present invention are preferably measured using a GPC (gel permeation chromatography) method and determined using a standard polystyrene calibration curve. In the measurement by gel permeation chromatography in the present invention, HLC-8020GPC (manufactured by Tosoh Corporation) is used, and TSKgel Super HZ MH, TSK gel Super HZ4000, TSKgel SuperHZ200 (manufactured by Tosoh Corporation, 4.6 mm ID × 15 cm) are used as columns. ), And THF (tetrahydrofuran) is preferably used as an eluent.
In addition, the polyfunctional polymerizable compound other than (Component C) Component A in the present invention does not include an oligomer having a weight average molecular weight of 1,500 or more, and also in the “polyfunctional polymerizable compound” in the present invention. And oligomers having a weight average molecular weight of 1,500 or more are not included.
As the oligomer, those having a polymerizable group as a functional group are preferred, those having an ethylenically unsaturated group are more preferred, and those having a (meth) acryloyl group are particularly preferred.
The number of functional groups contained in the oligomer is preferably from 1 to 15, more preferably from 2 to 6, even more preferably from 2 to 4, and particularly preferably 2 from the viewpoint of the balance between flexibility and curability.

  As the oligomer in the present invention, polyester (meth) acrylate, olefin (ethylene oligomer, propylene oligomer, butene oligomer, etc.), vinyl (styrene oligomer, vinyl alcohol oligomer, vinyl pyrrolidone oligomer, (meth) acrylate oligomer, etc.), Diene (butadiene oligomer, chloroprene rubber, pentadiene oligomer, etc.), ring-opening polymerization (di-, tri-, tetraethylene glycol, polyethylene glycol, polyethylimine, etc.), polyaddition (oligoester (meth) acrylate, polyamide) Oligomer, polyisocyanate oligomer), addition condensation oligomer (phenol resin, amino resin, xylene resin, ketone resin, etc.), amine-modified polyester oligomer, etc. Door can be. Among these, urethane (meth) acrylate and polyester (meth) acrylate are more preferable, and urethane (meth) acrylate is particularly preferable because an ink composition having excellent curability and adhesion can be obtained. An oligomer may be used in combination of a plurality of types in addition to a single type.

  Examples of the urethane (meth) acrylate include aliphatic urethane (meth) acrylate and aromatic urethane (meth) acrylate. For details, refer to the oligomer handbook (supervised by Junji Furukawa, Chemical Daily Co., Ltd.).

Urethane (meth) acrylates include U-2PPA, U-4HA, U-6HA, U-6LPA, U-15HA, U-324A, UA-122P, UA5201, and UA-512 manufactured by Shin-Nakamura Chemical Co., Ltd. CN964A85, CN964, CN959, CN962, CN963J85, CN965, CN982B88, CN981, CN983, CN996, CN9002, CN9007, CN9010, CN9011, CN9810 EB204, EB230, EB244, EB245, EB270, EB284, EB285, EB810, EB4830, EB4835, EB4858, EB1290, EB210, EB 15, EB4827, EB4830, EB4849, EB6700, EB204, EB8402, EB8804, include EB8800-20R like.
Examples of amine-modified polyester oligomers include EB524, EB80, EB81 manufactured by Daicel-Cytec, Inc., CN550, CN501, CN551, Rahn A., manufactured by Sartomer Japan, Inc. G. GENOMER 5275 made by the company is mentioned.

  The content of the oligomer is preferably 1 to 10% by mass, more preferably 2 to 8% by mass, and 3 to 7% by mass with respect to the total mass of the ink composition from the viewpoint of achieving both curability and adhesion. Further preferred.

<Colorant>
The ink composition of the present invention can contain a colorant, if necessary.
Although there is no restriction | limiting in particular as a coloring agent, The pigment and oil-soluble dye which were excellent in weather resistance and were rich in color reproducibility are preferable, and it can select and use arbitrarily from well-known coloring agents, such as a soluble dye. As the colorant, it is preferable to select a compound that does not function as a polymerization inhibitor from the viewpoint of not reducing the sensitivity of the curing reaction by actinic radiation.

The pigment functions as a colorant for the ink composition. However, in the present invention, the fine pigment having a particle diameter as described later is uniformly and stably dispersed in the ink composition. The ink composition has excellent color developability, and can form a sharp and excellent weather-resistant image.
The pigment is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include known organic pigments and inorganic pigments. Resin particles dyed with dyes, commercially available pigment dispersions, The surface-treated pigment (for example, a pigment dispersed in an insoluble resin or the like using a pigment as a dispersion medium, or a pigment grafted with a resin on the pigment surface) can also be used. Examples of the pigment include, for example, “Spirit Dictionary” (2000), edited by Seijiro Ito. Herbst, K.M. Examples include those described in Hunger “Industrial Organic Pigments”, Japanese Patent Application Laid-Open No. 2002-12607, Japanese Patent Application Laid-Open No. 2002-188025, Japanese Patent Application Laid-Open No. 2003-26978, and Japanese Patent Application Laid-Open No. 2003-342503.

Examples of the organic pigment and inorganic pigment include yellow pigment, magenta pigment, blue, cyan pigment, green pigment, orange pigment, brown pigment, violet pigment, black pigment, white pigment, and the like. Pigment, blue, cyan pigment, green pigment, orange pigment, brown pigment, violet pigment, and black pigment are preferable.
The colorant is preferably an organic pigment.
Examples of organic pigments include azo pigments, polycyclic pigments, lake pigments, and the like.

  The yellow pigment is a pigment exhibiting a yellow color. I. Pigment Yellow 1 (Fast Yellow G etc.), C.I. I. Monoazo pigments such as CI Pigment Yellow 74; I. Pigment Yellow 12 (disaji yellow, etc.), C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 3, C.I. I. Pigment yellow 16, C.I. I. Pigment yellow 83, C.I. I. Pigment yellow 155, C.I. I. Disazo pigments such as CI Pigment Yellow 219; I. Non-benzidine azo pigments such as CI Pigment Yellow 180; I. Azo lake pigments such as C.I. Pigment Yellow 100 (eg Tartrazine Yellow Lake); I. Pigment yellow 95 (condensed azo yellow, etc.), C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 128, C.I. I. Condensed azo pigments such as C.I. Pigment Yellow 166; I. Pigment Yellow 115 (quinoline yellow lake, etc.), etc., acidic dye lake pigments, C.I. I. Basic dye lake pigments such as C.I. Pigment Yellow 18 (such as thioflavine lake); I. Anthraquinone pigments such as C.I. Pigment Yellow 24 (Flavantron Yellow, etc.); I. Quinophthalone pigments such as C.I. Pigment Yellow 110 (e.g., Quinophthalone Yellow); I. Pigment yellow 139 (isoindoline yellow, etc.) and the like, isoindoline pigments such as C.I. I. Pyrazolone pigments such as C.I. Pigment Yellow 60 (Pyrazolone Yellow, etc.); I. Pigment yellow 120, C.I. I. Pigment yellow 154, C.I. I. Pigment yellow 167, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 175, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 181, C.I. I. An acetolone pigment such as C.I. Pigment Yellow 194; I. Pigment complex pigments such as CI Pigment Yellow 150, C.I. I. Nitroso pigments such as C.I. Pigment Yellow 153 (nickel nitroso yellow, etc.), C.I. I. Metal complex azomethine pigments such as CI Pigment Yellow 117 (copper azomethine yellow, etc.); I. And pigment yellow.

  The magenta pigment is a pigment exhibiting red or magenta color. I. Monoazo pigments such as CI Pigment Red 3 (Toluidine Red, etc.); I. Pigment red 1, C.I. I. Pigment red 4, C.I. I. Pigment Red 6 and other B-naphthol pigments, C.I. I. Disazo pigments such as CI Pigment Red 38 (Pyrazolone Red B, etc.); I. Pigment Red 53: 1 (Lake Red C, etc.) and C.I. I. Pigment Red 57: 1 (Brilliant Carmine 6B etc.), C.I. I. Pigment red 52: 1, C.I. I. Pigment Red 48 (B-oxynaphthoic acid lake, etc.) azo lake pigment, C.I. I. Pigment red 144, C.I. I. Pigment red 166, C.I. I. Pigment red 220, C.I. I. Pigment red 214, C.I. I. Pigment red 221, C.I. I. Condensed azo pigments such as C.I. Pigment Red 242 (condensed azo red and the like), C.I. I. Pigment Red 174 (Phloxine B lake, etc.), C.I. I. Pigment Red 172 (Erythrosin Lake, etc.) and other acidic dye lake pigments, C.I. I. Basic dye lake pigments such as C.I. Pigment Red 81 (Rhodamine 6G 'lake, etc.); I. Anthraquinone pigments such as C.I. Pigment Red 177 (eg, dianthraquinonyl red); I. Thioindigo pigments such as CI Pigment Red 88 (Thioindigo Bordeaux and the like), C.I. I. Perinone pigments such as CI Pigment Red 194 (perinone red, etc.); I. Pigment red 149, C.I. I. Pigment red 179, C.I. I. Pigment red 178, C.I. I. Pigment red 190, C.I. I. Pigment red 224, C.I. I. Perylene pigments such as CI Pigment Red 123; I. Pigment violet 19 (unsubstituted quinacridone), C.I. I. Pigment red 122, C.I. I. Pigment red 262, C.I. I. Pigment red 207, C.I. I. Quinacridone pigments such as CI Pigment Red 209; I. Pigment Red 180 (Isoindolinone Red 2BLT, etc.), etc., isoindolinone pigments, C.I. I. Alizarin lake pigments such as C.I. Pigment Red 83 (Mada Lake, etc.); I. Pigment red 171, C.I. I. Pigment red 175, C.I. I. Pigment red 176, C.I. I. Pigment red 185, C.I. I. Naphtholone pigments such as CI Pigment Red 208; I. Naphthol AS-based lake pigments such as CI Pigment Red 247; I. Pigment red 2, C.I. I. Pigment red 5, C.I. I. Pigment red 21, C.I. I. Pigment red 170, C.I. I. Pigment red 187, C.I. I. Pigment red 256, C.I. I. Pigment red 268, C.I. I. Naphthol AS pigments such as C.I. Pigment Red 269; I. Pigment red 254, C.I. I. Pigment red 255, C.I. I. Pigment red 264, C.I. I. And diketopyrrolopyrrole pigments such as CI Pigment Red 272.

  The cyan pigment is a pigment exhibiting blue or cyan color. I. Disazo pigments such as C.I. Pigment Blue 25 (dianisidine blue, etc.); I. Pigment blue 15, C.I. I. Pigment blue 15: 1, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4, C.I. I. Pigment blue 15: 6, C.I. I. Phthalocyanine pigments such as C.I. Pigment Blue 16 (phthalocyanine blue, etc.); I. Acidic dye lake pigments such as C.I. Pigment Blue 24 (peacock blue lake, etc.); I. Basic dye lake pigments such as C.I. Pigment Blue 1 (such as Biclothia Pure Blue BO Lake); I. Anthraquinone pigments such as C.I. Pigment Blue 60 (Indantron Blue, etc.); I. And alkaline blue pigments such as CI Pigment Blue 18 (Alkali Blue V-5: 1).

The green pigment is a pigment exhibiting a green color. I. Pigment green 7 (phthalocyanine green), C.I. I. Phthalocyanine pigments such as C.I. Pigment Green 36 (phthalocyanine green); I. Pigment green 8, C.I. I. And azo metal complex pigments such as CI Pigment Green 10.
The orange pigment is a pigment exhibiting an orange color. I. Pigment Orange 66 (Isoindoline Orange) and the like, C.I. I. Anthraquinone pigments such as C.I. Pigment Orange 51 (dichloropyrantron orange); I. Pigment orange 2, C.I. I. Pigment orange 3, C.I. I. Pigment Orange 5 and the like-naphthol pigments such as C.I. I. Pigment orange 4, C.I. I. Pigment orange 22, C.I. I. Pigment orange 24, C.I. I. Pigment orange 38, C.I. I. Naphthol AS pigments such as CI Pigment Orange 74; I. Pigment Orange 61 and other isoindolinone pigments, C.I. I. Perinone pigments such as CI Pigment Orange 43; I. Pigment orange 15, C.I. I. Disazo pigments such as CI Pigment Orange 16; I. Pigment orange 48, C.I. I. Quinacridone pigments such as CI Pigment Orange 49; I. Pigment orange 36, C.I. I. Pigment orange 62, C.I. I. Pigment orange 60, C.I. I. Pigment orange 64, C.I. I. An acetolone pigment such as C.I. Pigment Orange 72; I. Pigment orange 13, C.I. I. And pyrazolone pigments such as CI Pigment Orange 34.
The brown pigment is a pigment exhibiting a brown color. I. Pigment brown 25, C.I. I. And naphthron pigments such as CI Pigment Brown 32.
The violet pigment is a pigment exhibiting a purple color. I. Naphtholone pigments such as CI Pigment Violet 32, C.I. I. Perylene pigments such as CI Pigment Violet 29, C.I. I. Pigment violet 13, C.I. I. Pigment violet 17, C.I. I. Naphthol AS pigments such as CI Pigment Violet 50, C.I. I. Pigment violet 23, C.I. I. And dioxazine pigments such as CI Pigment Violet 37.

The black pigment is a pigment exhibiting black color, such as carbon black, titanium black, C.I. I. Indazine pigments such as CI Pigment Black 1 (aniline black); I. Pigment black 31, C.I. I. And perylene pigments such as CI Pigment Black 32.
Examples of the white pigment include basic lead carbonate (2PbCO ₃ Pb (OH) ₂ , so-called silver white), zinc oxide (ZnO, so-called zinc white), titanium oxide (TiO ₂ , so-called titanium white), And strontium titanate (SrTiO ₃ , so-called titanium strontium white). The inorganic particles used for the white pigment may be a simple substance or, for example, oxides such as silicon, aluminum, zirconium and titanium, organometallic compounds, and composite particles with organic compounds.
Above all, the titanium oxide has a lower specific gravity than other white pigments, a large refractive index, and is chemically and physically stable, so that it has a high hiding power and coloring power as a pigment, and further, an acid or alkali. Since it is excellent in durability against other environments, it is preferably used. In addition to the titanium oxide, another white pigment (may be other than the above-described white pigment) may be used in combination.

For dispersion of the pigment, for example, a ball mill, a sand mill, an attritor, a roll mill, a jet mill, a homogenizer, a paint shaker, a kneader, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, etc. Can be preferably used.
In the present invention, it is particularly preferable to add a dispersant described later when dispersing the pigment.
In addition, when dispersing the pigment, a synergist corresponding to various pigments may be added as a dispersion aid, if necessary. The content of the dispersion aid in the ink composition is preferably 1 to 50 parts by mass with respect to 100 parts by mass of the pigment.

  The dispersion medium used when the pigment is dispersed in the ink composition is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the polymerizable compound having a low molecular weight may be selected from the dispersion medium. Alternatively, a solvent may be used as the dispersion medium. However, the ink composition of the present invention is a radiation curable ink, and is preferably solvent-free without containing the above-mentioned solvent in order to cure the ink after it is applied to the recording medium. This is because if the solvent remains in the cured ink image, the solvent resistance is deteriorated or a VOC (Volatile Organic Compound) problem of the remaining solvent occurs. For this reason, it is preferable to use the polymerizable compound as the dispersion medium, and to select the polymerizable compound having the lowest viscosity among them in terms of dispersion suitability and handling property of the ink composition.

There is no restriction | limiting in particular as an average particle diameter of the said pigment, Although it can select suitably according to the objective, Since it is excellent in color developability so that it is fine, about 0.01-0.4 micrometer is preferable, and 0.02- 0.2 μm is more preferable. The maximum particle size of the pigment is preferably 3 μm, more preferably 1 μm. The particle size of the pigment can be adjusted by selecting the pigment, dispersant, dispersion medium, dispersion conditions, filtration conditions, etc., and controlling the particle size of the pigment prevents clogging of the head nozzle. In addition, ink storage stability, ink transparency and curing sensitivity can be maintained.
The particle size of the pigment in the ink composition can be measured by a known measurement method. Specifically, it can be measured by a centrifugal sedimentation light transmission method, an X-ray transmission method, a laser diffraction / scattering method, and a dynamic light scattering method.

  The content of the colorant in the ink composition is appropriately selected depending on the color and purpose of use, but is preferably 0.01 to 30% by mass with respect to the mass of the entire ink composition.

<Dispersant>
The ink composition of the present invention preferably contains a dispersant. In particular, when a pigment is used, a dispersant is preferably contained in order to stably disperse the pigment in the ink composition. As the dispersant, a polymer dispersant is preferable. In the present invention, the “polymer dispersant” means a dispersant having a weight average molecular weight of 1,000 or more.

Examples of the polymer dispersant include DISPERBYK-101, DISPERBYK-102, DISPERBYK-103, DISPERBYK-106, DISPERBYK-111, DISPERBYK-161, DISPERBYK-162, DISPERBYK-163, DISPERBYK-164, DISPERBYK-166, DISPERBYK-166, and DISPERBYK-166. , DISPERBYK-168, DISPERBYK-170, DISPERBYK-171, DISPERBYK-174, DISPERBYK-182 (manufactured by BYK Chemie); EFKA7462, EFKA7500, EFKA7570, EFKA7575, EFKA7580 (manufactured by Efka Additive); Disperse Aid 6, Disperse Aid 8, Disperse Aid 15, Disperse Aid 9100 (manufactured by Sannopco); Solsperse (SOLSPERSE) 3000 Various Solsperse dispersants (manufactured by Noveon) such as 5000, 9000, 12000, 13240, 13940, 17000, 22000, 24000, 26000, 28000, 32000, 36000, 39000, 41000, 71000; Adeka Pluronic L31, F38, L42, L44 , L61, L64, F68, L72, P95, F77, P84, F87, P94, L101, P103, F108, L121, -123 (manufactured by ADEKA Corporation), Ionette S-20 (manufactured by Sanyo Chemical Industries, Ltd.); Disparon KS-860, 873SN, 874 (polymer dispersing agent), # 2150 (aliphatic polycarboxylic acid), # 7004 (polyether ester type) (manufactured by Enomoto Kasei Co., Ltd.).
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 mass with respect to the mass of the entire ink composition.

<Surfactant>
A surfactant may be added to the ink composition of the present invention in order to impart 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 dialkyl sulfosuccinates, alkyl naphthalene sulfonates, 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. Moreover, you may use a fluorine-type surfactant (for example, organic fluoro compound etc.) and silicone type surfactant (for example, polysiloxane compound etc.) as said surfactant. The organic fluoro compound is preferably hydrophobic. Examples of the organic fluoro compound 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. The polysiloxane compound is preferably a modified polysiloxane compound in which an organic group is introduced into a part of the methyl group of dimethylpolysiloxane. Examples of modification include polyether modification, methylstyrene modification, alcohol modification, alkyl modification, aralkyl modification, fatty acid ester modification, epoxy modification, amine modification, amino modification, mercapto modification, etc. is not. These modification methods may be used in combination. Of these, polyether-modified polysiloxane compounds are preferred from the viewpoint of improving ejection stability in inkjet. Examples of polyether-modified polysiloxane compounds include, for example, SILWET L-7604, SILWET L-7607N, SILWET FZ-2104, SILWET FZ-2161 (manufactured by Nippon Unicar Co., Ltd.), BYK306, BYK307, BYK331, BYK333, BYK347. , BYK348 and the like (manufactured by BYK Chemie), KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, Examples thereof include KF-6020, X-22-6191, X-22-4515, KF-6011, KF-6012, KF-6015, and KF-6017 (manufactured by Shin-Etsu Chemical Co., Ltd.).
Of these, silicone surfactants are preferred.
The content of the surfactant in the ink composition of the present invention is appropriately selected depending on the purpose of use, but is preferably 0.0001 to 1% by mass with respect to the mass of the entire ink composition.

<Solvent>
In order to improve the adhesion to the recording medium, it is also effective to add a 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, ethylene glycol monomethyl ether, ethylene glycol dimethyl ether and triprolylene Examples include glycol ether solvents such as glycol monomethyl ether, cyclic ester solvents such as γ-butyrolactone, amide solvents such as 2-methylpyrrolidone and 2-pyrrolidone. It is.
In this case, it is effective to add the solvent within a range that does not cause the problem of solvent resistance and VOC, and the amount of the solvent is preferably 0.1 to 5% by mass with respect to the total mass of the ink composition. The mass% is more preferable.
As a dispersion medium for various components such as pigments in the ink composition, a solvent may be added, or a solvent-free polymerizable compound may be used as a dispersion medium. It is an active energy ray-curable ink composition, and it is preferable that the ink composition be solvent-free in order to be cured after the ink composition is applied onto a recording medium. This is because if the solvent remains in the cured ink image, the solvent resistance is deteriorated or a VOC (Volatile Organic Compound) problem of the remaining solvent occurs. From such a viewpoint, a polymerizable compound is used as the dispersion medium, and among these, it is preferable to select a polymerizable compound having the lowest viscosity from the viewpoint of improving the dispersion suitability and the handling property of the ink composition.

In the ink composition of the present invention, various additives can be used in combination according to the purpose. For example, an ultraviolet absorber can be used from the viewpoint of improving the weather resistance of the obtained image and preventing discoloration. In addition, an antioxidant can be added to improve the stability of the ink composition.
The ink composition of the present invention may contain various known additives in addition to the above-described components.
Specific additives other than the above include, for example, various organic and metal complex anti-fading agents, potassium thiocyanate, lithium nitrate, ammonium thiocyanate, dimethylamine hydrochloride for the purpose of controlling ejection properties. Examples thereof include conductive salts such as polymer compounds for the purpose of adjusting film properties.

Various polymer compounds can be added to the ink composition of the present invention for the purpose of adjusting film properties. High molecular compounds include acrylic polymers, polyvinyl butyral resins, polyurethane resins, polyamide resins, polyester resins, epoxy resins, phenol resins, polycarbonate resins, polyvinyl butyral resins, polyvinyl formal resins, shellacs, vinyl resins, acrylic resins. Rubber resins, waxes and other natural resins can be used. Two or more of these may be used in combination.
In addition to this, if necessary, for example, basic compounds, leveling additives, matting agents, waxes for adjusting film properties, adhesion to recording media such as polyolefin and polyethylene terephthalate (PET). In order to improve this, a tackifier (tackifier) that does not inhibit the polymerization can be contained.

The ink composition of the present invention preferably has a viscosity of 0.5 to 30 mPa · s at a temperature at the time of discharge in consideration of dischargeability from an inkjet nozzle, and preferably 0.5 to 20 mPa · s. It is more preferable that it is 1-15 mPa · s. It is preferable that the composition ratio is appropriately adjusted and determined so as to be within this range.
The viscosity of the ink composition at 25 ° C. (room temperature) is preferably 1 mPa · s or more and 200 mPa · s or less, more preferably 2 mPa · s or more and 50 mPa · s or less, and 2.5 mPa · s or less. More preferably, it is 30 mPa · s or less. By setting the viscosity at room temperature high, even when a porous recording medium is used, the ink composition can be prevented from penetrating into the recording medium, the uncured monomer can be reduced, and the odor can be reduced. Dot blurring at the time of droplet landing can be suppressed, and as a result, the image quality is improved. Further, when the viscosity of the ink composition at 25 ° C. is 200 mPa · s or less, delivery of the ink composition to an inkjet head or the like in the apparatus is easy.

  The surface tension of the ink composition of the present invention is preferably 20 to 40 mN / m, and more preferably 23 to 35 mN / m. When recording on various recording media such as polyolefin, PET, coated paper, and uncoated paper, 20 mN / m or more is preferable from the viewpoint of bleeding and penetration, and 35 mN / m or less is preferable from the viewpoint of wettability.

The ink composition of the present invention thus prepared is suitable for recording by printing the ink composition on a recording medium with an ink jet printer, and then curing the printed ink composition by irradiation with active rays. It can be carried out.
Since the printed matter obtained from the ink composition of the present invention is excellent in the strength of the image portion, in addition to the image formation by the ink composition, various other methods such as the formation of an ink receiving layer (image portion) of a lithographic printing plate can be used. Can be used for applications.

(Inkjet recording method, inkjet recording apparatus and printed matter)
In the ink jet recording method of the present invention, the ink composition of the present invention is ejected onto a recording medium (support, recording material, etc.) for ink jet recording, and the ink composition ejected onto the recording medium is irradiated with active energy rays. The inkjet ink composition is cured to form an image.

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 ) an active line on the ejected ink composition. It is preferable to include a step of curing the ink composition by irradiation.
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.
In addition, the inkjet recording method of the present invention is a multi-pass mode in which the above steps (a ¹ ) and (b ¹ ) are performed twice or more on the same part on the recording medium, that is, the same part is printed by overstrike. Preferably it is done. By using the ink composition of the present invention, an image superior in glossiness can be obtained when printing is performed in a multipass mode.
The printed matter of the present invention is a printed matter recorded with the ink composition of the present invention, and is preferably a printed matter recorded by the ink jet recording method of the present invention.

The ink composition of the present invention is suitable for package printing, and particularly suitable for package printing for food packaging. In that case, the inkjet recording method preferably includes the following steps in this order.
(Step a) A step of discharging an inkjet ink composition from an inkjet head and printing on a support for a package having a film thickness of 150 μm or less, and
(Step b) Step of irradiating the ejected inkjet ink composition with active rays

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

<Inkjet recording apparatus>
There is no restriction | limiting in particular as an inkjet recording device which can be 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 be used to discharge the ink composition onto the recording medium in steps (a ¹ ) and (a) of the inkjet recording method of the present invention. it can.

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 active energy ray 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, the ink composition of the present invention is preferably provided with a means for stabilizing the temperature of the ink composition in the ink jet recording apparatus because the ink composition to be ejected is preferably kept at a constant temperature. The parts to be kept at a constant temperature are all the piping systems and members from the ink tank (intermediate tank if there is an intermediate tank) to the nozzle ejection surface. That is, heat insulation and heating can be performed from the ink supply tank to the inkjet head portion.
The temperature control method is not particularly limited, but for example, it is preferable to provide a plurality of temperature sensors in each piping portion and perform heating control according to the flow rate of the ink composition 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.

  A radiation curable ink composition such as the ink composition of the present invention generally has a higher viscosity than a water-based ink composition usually used in an ink composition for ink jet recording, and therefore has a large viscosity fluctuation due to temperature fluctuations during ejection. Viscosity fluctuation of the ink composition has a great influence on the change of the droplet size and the change of the droplet discharge speed, and thus causes the image quality deterioration. Therefore, it is necessary to keep the temperature of the ink composition during ejection as constant as possible. Therefore, in the present invention, the temperature control range of the ink composition is preferably set to ± 5 ° C. of the set temperature, more preferably ± 2 ° C. of the set temperature, and further preferably set temperature ± 1 ° C. .

Next, the (b ¹ ) step and the (b) step will be described.
The ink composition discharged onto the recording medium is cured by irradiating with active energy rays (active rays). This is because the polymerization initiator contained in the ink composition of the present invention is decomposed by irradiation with active energy rays to generate polymerization initiation species such as radicals, and the polymerization reaction of the polymerizable compound is a function of the initiation species. This is because it is created and promoted. At this time, if the sensitizer is present together with the polymerization initiator in the ink composition, the sensitizer in the system absorbs the active energy ray to be in an excited state, and the polymerization initiator is decomposed by contact with the polymerization initiator. It can be accelerated 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 active energy rays. Although the peak wavelength of the active energy ray depends on the absorption characteristics of the sensitizer, for example, it is preferably 200 to 600 nm, more preferably 300 to 450 nm, still more preferably 320 to 420 nm, The active energy ray is particularly preferably ultraviolet light having a peak wavelength in the range of 340 to 400 nm.

In addition, the polymerization initiation system of the ink composition of the present invention has sufficient sensitivity even with a low output active energy ray. Therefore, it is appropriate to cure the exposed surface with an illuminance of 10 to 4,000 mW / cm ² , more preferably 20 to 2,500 mW / cm ² .

Mercury lamps, gas / solid lasers, etc. are mainly used as active energy ray sources, and mercury lamps and metal halide lamps are widely used as light sources for curing UV photocurable ink jet recording ink compositions. Are known. 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.
In addition, a light emitting diode (LED) and a laser diode (LD) can be used as an active energy ray 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 active energy rays centered between 300 nm and 370 nm. Other ultraviolet LEDs are also available and can emit radiation in different ultraviolet bands. A particularly preferable active energy ray source in the present invention is a UV-LED, and a UV-LED having a peak wavelength at 340 to 400 nm is particularly preferable.
The maximum illumination intensity on the LED recording medium is preferably 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 suitably irradiated with such active energy rays for 0.01 to 120 seconds, more preferably for 0.1 to 90 seconds.
The irradiation conditions of active energy rays and the 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 composition discharge device, and the head unit and the light source are scanned by a so-called shuttle method. The irradiation with the active energy ray is performed for a certain period of time after the ink composition has landed (preferably 0.01 to 0.5 seconds, more preferably 0.01 to 0.3 seconds, and still more preferably 0.01 to 0.15). Seconds). As described above, by controlling the time from the landing of the ink composition to the irradiation to an extremely short time, it is possible to prevent the ink composition that has landed on the recording medium from bleeding before being cured. In addition, since the ink composition can be exposed to a porous recording medium before it 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 composition 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 ink compositions in order of low lightness, it becomes easy for the irradiation rays to reach the lower ink composition, 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 active energy rays.

The ink composition of the present invention is preferably used as an ink set comprising a plurality of ink jet recording inks.
In the inkjet recording method of the present invention, the order of the respective colored ink compositions to be ejected is not particularly limited, but is preferably applied to the recording medium from a colored ink composition having high brightness, and yellow, cyan, magenta When black is used, it is preferably applied on the recording medium in the order of yellow → cyan → magenta → black. In addition, when white is used in addition to this, it is preferable to apply on the recording medium in the order of white → yellow → cyan → magenta → black. Furthermore, the present invention is not limited to this, and the ink set of the present invention including at least seven colors of yellow, light cyan, light magenta, cyan, magenta, black and white ink compositions can be preferably used. In this case, it is preferable to apply on the recording medium in the order of white → light cyan → light magenta → yellow → cyan → magenta → black.

FIG. 1 is a schematic diagram of an ink jet recording apparatus preferably used in the present invention. The support 6 stretched on the support take-up rolls 5 and 5 ', which is a support transport means, is transported in the direction of the arrow, and is provided with an ink jet head provided with a droplet ejection head for discharging the ink composition of each color. In the unit 7, ink compositions (K: black, Y: yellow, M: magenta, C: cyan, W: white) of each color are ejected.
As shown in FIG. 1, the LED light source unit 1 is surrounded by an inert gas blanket 2 and is connected to an inert gas generator 4 via an inert gas pipe 3. An inert gas generator 4 which is a means for making the atmosphere in the inert gas blanket 2 an oxygen-poor atmosphere supplies an inert gas into the inert gas blanket 2 via an inert gas pipe 3. In the initial state, the atmosphere in the inert gas blanket 2 is air, but when the inert gas generator 4 is operated, the air in the inert gas blanket 2 is replaced with the inert gas. As described above, N ₂ or the like can be used as the inert gas.

The ink jet recording apparatus that can be suitably used in the ink jet recording method of the present invention is a nozzle row in which nozzles that discharge curable ink that is cured by application of active energy are arranged at a predetermined pitch P in the first direction. It is preferable. The ink jet recording apparatus preferably has at least N (N ≧ 4) nozzle rows for ejecting four colors of ink of cyan, magenta, yellow and black, respectively. Further, it is preferable that each nozzle row includes an ink jet head in which nozzles are arranged so as to be shifted by P / N in the first direction.
The first direction is preferably the recording medium conveyance direction (sub-scanning direction).
The inkjet head has a nozzle row for each of N (N ≧ 4) inks that eject at least four inks of cyan, magenta, yellow, and black, respectively, and at least cyan, magenta, yellow, and black. It is preferable to have a nozzle row for each of N (N ≧ 5) colors that respectively eject four color inks and at least one light ink, and at least cyan, magenta, yellow, black, light cyan, and It is more preferable to have a nozzle row for each of N (N ≧ 6) colors that respectively eject light magenta ink.

Each nozzle row of the inkjet head is a nozzle row in which nozzles that discharge curable ink that is cured by application of active energy are arranged at a predetermined pitch P in the first direction.
The pitch P is not particularly limited and may be any desired pitch, but is preferably 50 dpi or more (about 508 μm or less) and 600 dpi or less (about 42 μm or more).
The nozzle rows of the inkjet head are preferably arranged such that the nozzles are shifted in the first direction, and the nozzles are shifted by P / N in the first direction.
The method of shifting the nozzle rows is not particularly limited as long as the nozzle rows are at least shifted, and each nozzle may be shifted stepwise, or even if the shift between adjacent nozzle rows is P / N. , May be an integer multiple of P / N, or may be an arbitrary deviation. For example, in the case of a four-color nozzle row, a shifting method as shown in FIG. In particular, when the nozzles are shifted by P / N, it is preferable to shift the adjacent nozzle rows so that the deviation of the adjacent nozzle rows is not P / N as much as possible. It is particularly preferable that the shift is any (2 × P / N) or more.
In the first direction, each nozzle row of the ink jet head in the first direction from the most upstream side of the relative movement of the recording medium with respect to the ink jet head, in the case of four colors, is a black ink nozzle row, a yellow ink nozzle row, a cyan ink nozzle row. The magenta ink nozzle rows are preferably arranged in a shifted order. In the case of four colors and a total of six colors of light cyan and light magenta, the nozzle row for black ink, the nozzle row for yellow ink, the nozzle row for light magenta ink, the nozzle row for cyan ink, the nozzle row for light cyan ink, and for magenta ink It is preferable that the nozzle rows are arranged in a shifted order.

Further, in each nozzle row of the inkjet head, it is preferable that an ink nozzle having the lowest curing sensitivity is disposed on the most upstream side of the relative movement of the recording medium with respect to the inkjet head in the first direction, and the curing sensitivity is low. It is more preferable that the recording medium is disposed from upstream to downstream relative to the nozzle inkjet head in order from the ink. In the above aspect, since the ink of the nozzles arranged on the upstream side of the relative movement of the recording medium is arranged in a layer closer to the recording surface of the recording medium so that an image is formed on the recording surface of the recording medium. An ink having a low curing sensitivity can be arranged in a layer closest to the recording surface, so that the state of the surface layer can be kept constant, and gloss unevenness can be reduced.
Of the four color inks, the ink with the lowest curing sensitivity is often a black ink, and the ink with the second lowest curing sensitivity is often a yellow ink.
In addition, the inkjet head has nozzle rows that discharge light cyan and light magenta inks as light ink, and each nozzle row of the inkjet head is arranged with the nozzles shifted by P / 6 in the first direction, In addition, a light cyan or light magenta nozzle may be disposed between the cyan nozzle and the magenta nozzle, between the magenta nozzle and the yellow nozzle, or between the yellow nozzle and the cyan nozzle. preferable.

The inkjet head may have a white ink nozzle row and / or a clear ink nozzle row. Since white ink and clear ink have little influence on gloss unevenness of the image, the white ink nozzle row and / or the clear ink nozzle row together with the other nozzle rows in the first direction. The nozzles may be arranged in a shifted manner or not.
Further, the white ink nozzle row and / or the clear ink nozzle row has N pieces of ink that discharge the respective inks of cyan, magenta, yellow, and black (preferably, light cyan and / or light magenta). It is preferable that one type is arranged on each side in the second direction of the nozzle row for each color. Specifically, for example, the arrangement shown in FIG.
In the inkjet recording method of the present invention, the clear ink may be used in the same manner as the colored ink, or may be used for forming an undercoat layer or an overcoat layer.

  The number of nozzles arranged at a predetermined pitch P of the nozzle row in the inkjet is not particularly limited as long as it is 2 or more, but is preferably 4 or more and 1,024 or less, and more preferably 8 or more and 512 or less. More preferred.

The ink jet head used in the ink jet recording method of the present invention is preferably an ink jet head having a non-liquid repellent treatment nozzle plate.
As the nozzle plate having the nozzle rows arranged at the pitch P, known ones can be used. For example, US Pat. No. 7,011,396, US Patent Application Publication No. 2009/02900000 Etc. can be preferably used. Such a nozzle plate is mounted on, for example, an on-demand inkjet head using a piezo drive system manufactured by FUJIFILM Dimatix. Specific examples thereof include S-class and Q-class Sapphire.

  It is more preferable that the nozzle plate has at least part of the surface facing the recording medium that has been subjected to non-liquid repellent treatment (ink affinity treatment). As the non-liquid repellent treatment method, a known method can be used and is not limited. For example, (1) a method of thermally oxidizing the surface of a nozzle plate made of silicon to form a silicon oxide film, and (2) silicon or Examples thereof include a method of oxidatively forming an oxide film other than silicon, a method of forming by sputtering, and (3) a method of forming a metal film. For details of these methods, reference can be made to US Patent Application Publication No. 2010/0141709.

  FIG. 4 is an external perspective view of another ink jet recording apparatus that can be suitably used in the ink jet recording method of the present invention. The ink jet recording apparatus 10 is a wide format printer that forms a color image on a recording medium 12 using ultraviolet curable ink (UV curable ink). A wide format printer is an apparatus suitable for recording a wide drawing range, such as a large poster or a commercial wall advertisement. Here, the one corresponding to A3 Nobi or higher is called “wide format”.

  The ink jet recording apparatus 10 includes an apparatus main body 20 and support legs 22 that support the apparatus main body 20. The apparatus main body 20 includes a drop-on-demand type ink jet head 24 that ejects ink toward a recording medium (medium) 12, a platen 26 that supports the recording medium 12, a guide mechanism 28 as a head moving unit, and a carriage 30. (An example of scanning means) is provided.

  The guide mechanism 28 is above the platen 26 and is perpendicular to the conveyance direction (X direction, first direction) of the recording medium 12 and parallel to the medium support surface of the platen 26 (Y direction, second direction). ) To extend along. The carriage 30 is supported so as to reciprocate in the Y direction along the guide mechanism 28. An ink jet head 24 is mounted on the carriage 30, and temporary curing light sources 32 </ b> A and 32 </ b> B that irradiate ink on the recording medium 12 with ultraviolet rays and main curing light sources 34 </ b> A and 34 </ b> B are mounted.

The temporary curing light sources 32A and 32B emit ultraviolet rays for temporarily curing (semi-curing) the ink so that adjacent droplets do not coalesce after the ink droplets ejected from the inkjet head 24 land on the recording medium 12. A light source for irradiation. The main curing light sources 34 </ b> A and 34 </ b> B are light sources that irradiate with ultraviolet rays for performing additional exposure after temporary curing and finally completely curing (main curing) the ink.
The term “semi-cured” in the present invention refers to a state from when the ink composition starts to fully cured.
Further, “completely cured” in the present invention refers to a state in which the inside and the surface of the ink composition are completely cured. Specifically, it is possible to determine whether or not the ink composition has been transferred to the permeation medium by pressing the permeation medium such as plain paper. That is, the case where no transfer is performed is called a completely cured state.

  The inkjet head 24, the temporary curing light sources 32 </ b> A and 32 </ b> B, and the main curing light sources 34 </ b> A and 34 </ b> B disposed on the carriage 30 move integrally with the carriage 30 along the guide mechanism 28.

  As will be described later, the recording medium 12 is not limited to any material such as paper, non-woven fabric, vinyl chloride, synthetic chemical fiber, polyethylene resin, polyester resin, and tarpaulin, and may be a permeable medium or a non-permeable medium. Instead, various media can be used. The recording medium 12 is fed in a roll paper state (see FIG. 5) from the back side of the apparatus, and after printing is wound up by a winding roller (not shown in FIG. 4, reference numeral 44 in FIG. 5) on the front side of the apparatus. (Example of moving means). Ink droplets are ejected from the inkjet head 24 to the recording medium 12 conveyed on the platen 26, and the temporary curing light sources 32A and 32B and the main curing light sources 34A and 34B are applied to the ink droplets attached on the recording medium 12. Ultraviolet rays are irradiated.

  In FIG. 4, a mounting portion 38 for the ink cartridge 36 is provided on the left front surface of the apparatus main body 20. The ink cartridge 36 is a replaceable ink supply source (ink tank) that stores ultraviolet curable ink. The ink cartridge 36 is provided corresponding to each color ink used in the inkjet recording apparatus 10 of this example. Each color-specific ink cartridge 36 is connected to the inkjet head 24 by an ink supply path (not shown) formed independently. When the remaining amount of ink for each color is low, the ink cartridge 36 is replaced.

  Although not shown, a maintenance unit for the inkjet head 24 is provided on the right side of the apparatus main body 20 toward the front. The maintenance unit is provided with a cap for keeping the ink-jet head 24 moisturized during non-printing and a wiping member (blade, web, etc.) for cleaning the nozzle surface (ink ejection surface) of the ink-jet head 24. . The cap for capping the nozzle surface of the inkjet head 24 is provided with an ink receiver for receiving ink droplets discharged from the nozzle for maintenance.

[Description of recording medium transport path]
FIG. 5 is an explanatory diagram schematically showing a recording medium conveyance path in the inkjet recording apparatus 10. As shown in FIG. 5, the platen 26 is formed in an inverted bowl shape, and the upper surface thereof serves as a support surface of the recording medium 12 (referred to as “medium support surface”). A pair of nip rollers 40 that are recording medium conveying means for intermittently conveying the recording medium 12 are disposed on the upstream side in the recording medium conveying direction (X direction) in the vicinity of the platen 26. The nip roller 40 moves the recording medium 12 on the platen 26 in the X direction.

  The recording medium 12 sent out from a supply-side roll (referred to as a “feed-out supply roll”) 42 that constitutes a roll-to-roll type medium conveying means is fed to the entrance of the printing unit (upstream of the platen 26 in the recording medium conveying direction). Are intermittently conveyed in the X direction by a pair of nip rollers 40 provided on the side). The recording medium 12 that has reached the printing unit immediately below the ink jet head 24 is printed by the ink jet head 24 and is taken up by the take-up roller 44 after printing. A guide 46 for the recording medium 12 is provided on the downstream side of the printing unit in the recording medium conveyance direction.

  A temperature adjusting unit 50 for adjusting the temperature of the recording medium 12 during printing is provided on the back surface (the surface opposite to the surface supporting the recording medium 12) of the platen 26 at a position facing the inkjet head 24 in the printing unit. Is provided. When the recording medium 12 at the time of printing is adjusted to a predetermined temperature, the physical properties such as the viscosity of the ink droplets that have landed on the recording medium 12 and the surface tension become the desired values, and the desired dot diameter is set. Can be obtained. In addition, as needed, the pre temperature control part 52 may be provided in the upstream of the temperature control part 50, and the after temperature control part 54 may be provided in the downstream of the temperature control part 50.

[Description of inkjet head]
FIG. 6 is a plan perspective view showing an example of an arrangement form of the inkjet head 24 arranged on the carriage 30, the temporary curing light sources 32A and 32B, and the main curing light sources 34A and 34B.

  The inkjet head 24 includes nozzle rows 61CL, 61W, 61LM, 61K for ejecting ink for each color of CL (clear), W (white), LM, K, C, M, Y, LC. 61C, 61M, 61Y, 61LC, 61CL, 61W. In FIG. 6, the nozzle rows are indicated by dotted lines and are shown in a simplified manner, and the displacement of each nozzle row and the individual illustration of the nozzles are omitted. In the following description, the nozzle rows 61CL, 61W, 61LM, 61K, 61C, 61M, 61Y, 61LC, 61CL, and 61W may be collectively referred to as the nozzle row with reference numeral 61.

  The types of ink colors (number of colors) and color combinations are not limited to those shown in FIG. For example, a form in which the LC and LM nozzle arrays are omitted, a form in which the CL and W nozzle arrays are omitted, and a form in which a nozzle array for ejecting special color ink is added are possible. Further, there is no particular limitation on the arrangement order of the nozzle rows for each color in the Y direction.

  By forming a head module for each color nozzle row 61 and arranging them, it is possible to form an inkjet head 24 capable of color drawing. For example, the head modules 24CL, 24W, 24LM, 24K, 24C, 24M, 24Y, and 24LC having nozzle arrays 61CL, 61W, 61LM, 61K, 61C, 61M, 61Y, and 61LC, respectively, are arranged in the Y direction of the carriage 30. It is also possible to arrange them at regular intervals.

  Each of the color-specific head modules 24CL, 24W, 24LM, 24K, 24C, 24M, 24Y, and 24LC may be interpreted as an “inkjet head”. Alternatively, a configuration in which an ink flow path is formed separately for each color inside one inkjet head 24 and a nozzle array that discharges a plurality of colors of ink with one head is also possible.

  Each nozzle row 61 has a plurality of nozzles arranged in a line (linearly) along the X direction at regular intervals. In the inkjet head 24 of this example, the arrangement pitch (nozzle pitch) of the nozzles constituting each nozzle row 61 is 254 μm (100 dpi), the number of nozzles constituting one nozzle row 61 is 256 nozzles, and the total length of the nozzle row 61 Lw (corresponding to “nozzle row length”, sometimes referred to as “nozzle row width”) is approximately 65 mm (254 μm × 255 = 64.8 mm).

  The nozzle arrays 61LM, 61K, 61C, 61M, 61Y, and 61LC are arranged such that each nozzle is shifted in the X direction (not shown), and the K ink having the lowest curing sensitivity is ejected from the upstream side in the media conveyance direction. Are arranged in the order of the nozzle row 61 </ b> K that performs, and the nozzle row 61 </ b> Y that discharges Y ink having the second lowest curing sensitivity. Further, LM ink and LC ink nozzles (not shown) are arranged between the Y ink, C ink, and M ink nozzles that are dark inks. Note that dark ink with lower curing sensitivity may be arranged on the upstream side in the media conveyance direction.

  Further, the discharge frequency is 15 kHz, and three types of discharge droplet amounts of 10 pl, 20 pl, and 30 pl can be distinguished by changing the drive waveform. That is, it is possible to form three sizes of dots, small dots, medium dots, and large dots.

  As an ink ejection method of the inkjet head 24, a method (piezo jet method) in which ink droplets are ejected by deformation of a piezoelectric element (piezo actuator) is employed. In addition to a configuration using an electrostatic actuator (electrostatic actuator method) as a discharge energy generating element, a heating element (heating element) such as a heater is used to heat ink to generate bubbles and to eject ink droplets with that pressure. It is also possible to adopt a form (thermal jet system).

[About the layout of ultraviolet irradiation equipment]
As shown in FIG. 6, provisional curing light sources 32 </ b> A and 32 </ b> B are disposed on the left and right sides of the scanning direction (Y direction) of the inkjet head 24. Further, main curing light sources 34 </ b> A and 34 </ b> B are arranged on the downstream side in the recording medium conveyance direction (X direction) of the inkjet head 24.
The ink droplets ejected from the nozzles of the inkjet head 24 and landed on the recording medium 12 are immediately irradiated with ultraviolet rays for temporary curing by the temporary curing light source 32A (or 32B) passing thereover. Ink droplets on the recording medium 12 that have passed through the printing area of the inkjet head 24 as the recording medium 12 is intermittently conveyed are irradiated with ultraviolet rays for main curing by the main curing light sources 34A and 34B.
The temporary curing light sources 32A and 32B and the main curing light sources 34A and 34B may be constantly turned on during the printing operation of the inkjet recording apparatus 10, or may be appropriately turned on and off as necessary.

[Configuration example of temporary curing light source]
As shown in FIG. 6, each of the temporary curing light sources 32A and 32B has a structure in which a plurality of UV-LED elements 33 are arranged. The two temporary curing light sources 32A and 32B have a common configuration. In this example, as the temporary curing light sources 32A and 32B, the LED element array in which six UV-LED elements 33 are arranged in a line along the X direction is illustrated, but the number of LED elements and the array form thereof are shown in this example. It is not limited. For example, a configuration in which a plurality of LED elements are arranged in a matrix in the X / Y direction is also possible.
The six UV-LED elements 33 are arranged so that UV irradiation can be performed at once on a region having the same width as the nozzle row width Lw of the inkjet head 24.

[Configuration example of the main curing light source]
As shown in FIG. 6, each of the main curing light sources 34A and 34B has a structure in which a plurality of UV-LED elements 35 are arranged. The two main curing light sources 34A and 34B have a common configuration. In the example of FIG. 6, as the main curing light sources 34A and 34B, an LED element array (6 × 2) in which six UV-LED elements 35 in the Y direction and two in the X direction are arranged in a matrix is illustrated. Yes.

  The arrangement of the UV-LED elements 35 in the X direction is related to the swath width described later, and has a width corresponding to 1 / n (n is a positive integer) of the nozzle row width Lw in one scan of the carriage 30. It is determined so that UV irradiation can be performed at once. In the example of FIG. 6, the UV-LED elements 35 are arranged so that a region having a width of 1/2 (n = 2) of the nozzle row width Lw can be irradiated at once.

  The number of LED elements of the main curing light source and the arrangement form thereof are not limited to the example of FIG. Further, the light sources of the temporary curing light sources 32A and 32B and the main curing light sources 34A and 34B are not limited to the UV-LED elements 33 and 35, and a UV lamp or the like can also be used.

[About drawing mode]
The inkjet recording apparatus 10 configured as described above is applied with multi-pass drawing control, and the print resolution can be changed by changing the number of print passes. For example, three types of drawing modes, a high production mode, a standard mode, and a high image quality mode, are prepared, and the printing resolution is different in each mode. The drawing mode can be selected according to the printing purpose and application.

In the high production mode, printing is executed with a resolution of 600 dpi (main scanning direction) × 400 dpi (sub-scanning direction). In the high production mode, a resolution of 600 dpi is realized by two passes (two scans) in the main scanning direction. First, dots are formed with a resolution of 300 dpi in the first scan (the forward path of the carriage 30). In the second scan (return pass), dots are formed such that the middle of the dots formed in the first scan (forward pass) is interpolated at 300 dpi, and a resolution of 600 dpi is obtained in the main scan direction.
On the other hand, in the sub-scanning direction, the nozzle pitch is 100 dpi, and dots are formed at a resolution of 100 dpi in the sub-scanning direction by one main scanning (one pass). Therefore, a resolution of 400 dpi is realized by performing interpolation printing by four-pass printing (four scans).
In this specification, the product of the number of passes in the main scanning direction and the number of passes in the sub-scanning direction is referred to as the number of passes in the drawing mode. Therefore, the number of passes in the high production mode is main scanning 2-pass printing × sub-scanning 4-pass printing = 8 passes.

In the standard mode, printing is performed with a resolution of 600 dpi × 800 dpi. This resolution can be obtained by 2-pass printing in the main scanning direction and 8-pass printing in the sub-scanning direction. That is, the number of passes in the standard mode is main scanning 2-pass printing × sub-scanning 8-pass printing = 16 passes.
In the high image quality mode, printing is performed with a resolution of 1,200 × 1,200 dpi, and this resolution is obtained with four passes in the main scanning direction and 12 passes in the sub-scanning direction. That is, the number of passes in the high image quality mode is main scanning 4 pass printing × sub scanning 12 pass printing = 48 passes.

  According to the inkjet recording apparatus 10 configured as described above, the heads of the respective color inks are shifted in the recording medium conveyance direction within the nozzle pitch, and the lower sensitivity ink heads are arranged on the upstream side in the recording medium conveyance direction. By arranging and recording the ink with higher sensitivity in the lower layer, it is possible to keep the state of the surface layer constant and reduce gloss unevenness.

  In the above-described embodiment, an example in which an image is formed using UV curable ink is described. However, the present invention can be applied to a case where curable ink that is cured by applying active energy is used. For example, an ink that is cured by X-ray, molecular beam, ion beam, or the like can be used.

<Recording medium>
The recording medium to which the ink composition of the present invention can be applied is not particularly limited, and various non-absorbing resin materials used for ordinary non-coated paper and coated paper, so-called soft packaging, or films thereof. A resin film molded into a shape can be used.
As various plastic films, for example, PET (polyethylene terephthalate) film, OPS (biaxially stretched polystyrene) film, OPP (biaxially stretched polypropylene) film, ONy (biaxially stretched nylon) film, PVC (polyvinyl chloride) film, Examples include PE (polyethylene) film, TAC (cellulose triacetate) film, and the like.
In addition, examples of plastics that can be used as a recording medium material include polycarbonate, acrylic resin, ABS (acrylonitrile-butadiene-styrene copolymer), polyacetal, PVA (polyvinyl alcohol), and rubbers. Metals and glasses can also be used as a recording medium.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, “part” and “%” are based on mass.

<Synthesis of Compound A>
To a 1 L three-necked flask equipped with a stir bar, 121 g (1 molar equivalent) of tris (hydroxymethyl) aminomethane (manufactured by Tokyo Chemical Industry Co., Ltd.), 84 ml of 50% aqueous potassium hydroxide solution and 423 ml of toluene were added and stirred. The reaction system was maintained at 20 to 25 ° C. in a water bath, and 397.5 g (7.5 molar equivalents) of acrylonitrile was added dropwise over 2 hours. After dropping, the mixture was stirred for 1.5 hours, and then 540 ml of toluene was added to the reaction system, the reaction mixture was transferred to a separatory funnel, and the aqueous layer was removed. The remaining organic layer was dried over magnesium sulfate, filtered through celite, and the solvent was distilled off under reduced pressure to obtain an intermediate (B): acrylonitrile adduct. Since the analysis results of the obtained substance by ¹ H-NMR and MS showed a good agreement with the known substance, it was used for the next reduction reaction without further purification.

24 g of the intermediate (B) obtained previously, 48 g of Ni catalyst (Raney nickel 2400, manufactured by WR Grace & Co.), 600 ml of 25% aqueous ammonia: methanol = 1: 1 solution were suspended in a 1 L autoclave. The reaction vessel was sealed. 10 MPa of hydrogen was introduced into the reaction vessel, and the reaction was carried out at a reaction temperature of 25 ° C. for 16 hours.
The disappearance of the raw materials was confirmed by ¹ H-NMR, the reaction mixture was filtered through Celite, and the Celite was washed several times with methanol. The filtrate was evaporated under reduced pressure to obtain intermediate (C): amine. The obtained material was used for the next reduction reaction without further purification.

To a 2 L three-necked flask equipped with a stirrer was added 30 g of the intermediate (C) obtained earlier, 120 g (14 molar equivalents) of NaHCO ₃ , 1 L of dichloromethane, and 50 ml of water, and 92. 8 g (10 molar equivalents) was added dropwise over 3 hours, and then stirred at room temperature (25 ° C.) for 3 hours. After confirming disappearance of the raw materials by ¹ H-NMR, the solvent of the reaction mixture was distilled off under reduced pressure, the reaction mixture was dried over magnesium sulfate, filtered through celite, and the solvent was distilled off under reduced pressure. Finally, it was purified by column chromatography (ethyl acetate / methanol = 4: 1) to obtain Compound A (yield 40%) as a yellow liquid at room temperature (25 ° C.). The obtained yellow liquid was identified by ¹ H-NMR, ¹³ C-NMR, IR, and MS under the following measurement conditions.
¹ H-NMR Solvent: deuterated chloroform, internal standard: TMS (tetramethylsilane)
¹³ C-NMR Solvent: deuterated chloroform, internal standard: TMS
It was coated on an IR copper foil, the reflection spectrum was measured, and converted to absorbance.
MS solvent: methanol / water = 9/1, 10 mM CH ₃ COONH ₄
The structure of Compound A is shown below.

(Preparation of each mill base)
<Preparation of yellow mill base>
Yellow pigment: NOVOPERM YELLOW H2G (manufactured by Clariant): 30 parts by mass ): 30 parts by mass · BYK168 (dispersant, manufactured by BYK Chemie): 40 parts by mass The above components were stirred to obtain a yellow mill base. The pigment mill base was prepared by placing in a disperser motor mill M50 (manufactured by Eiger) and dispersing for 8 hours at a peripheral speed of 9 m / s using zirconia beads having a diameter of 0.65 mm.

<Preparation of magenta mill base>
-Magenta pigment: CINQUASIA MAGENTA RT-355D (manufactured by Ciba Japan): 30 parts by mass-SR9003: 30 parts by mass-BYK168: 40 parts by mass The above ingredients were stirred under the same dispersion conditions as in the preparation of the yellow mill base, A magenta mill base was obtained.

<Preparation of cyan mill base>
-Cyan pigment: IRGALITE BLUE GLVO (manufactured by Ciba Japan): 30 parts by mass-SR9003: 30 parts by mass-BYK168: 40 parts by mass Got.

<Preparation of black mill base>
Black pigment: SPECIAL BLACK 250 (manufactured by Ciba Japan): 30 parts by mass SR9003: 30 parts by mass BYK168: 40 parts by mass The above ingredients are stirred under the same dispersion conditions as in the preparation of yellow mill base, Got.

(Examples 1 to 29 and Comparative Examples 1 to 7)
<Method for producing ink composition>
Each ink component described in Table 1 was stirred for 15 minutes at 2500 rpm using a mixer (Silverson L4R) to obtain a cyan ink composition 1. In the same manner, ink compositions of Examples 2 to 29 and Comparative Examples 1 to 7 having the compositions described in Tables 1 to 4 were obtained.

<Inkjet recording method>
-Device configuration-
As shown in FIG. 2, an apparatus including an inkjet head in which nozzle rows of the respective colors are arranged to be shifted was used. The details of each part are as follows.
Each of the yellow, magenta, cyan, and black color heads is a piezo-type inkjet head Q-class Sapphire QS-256 / 10 (manufactured by FUJIFILM DIMATIX, 256 nozzles (100 npi (nozzle per inch), minimum droplet amount 10 pL, 30 kHz) was used.
The light source is a temporary curing light source as shown in FIG. 6 (however, the nozzle arrangement of each color in the inkjet head is as shown in FIG. 2). , comprising two light sources arranged a wavelength 385 nm), using what is intensity 780mW / cm ^2, light-emitting diodes as the curing light source (UV-LED, Nichia Corp. NC4U134, wavelength 385 nm) Were used, which had two light sources with an illuminance of 1,500 mW / cm ² .
The ink supply system consists of an ink pack, supply piping, deaeration filter SEPAREL EF-G2 (manufactured by DIC Corporation), an ink supply tank immediately before the inkjet head, a deaeration filter, and a piezo-type inkjet head. Then, the pressure was reduced to 0.5 atm.

-Image formation-
Image formation was performed using the apparatus configured as described above. In discharging the ink composition, the viscosity at the time of discharging was optimized by adjusting the discharging temperature. We also optimized the discharge waveform. As a result, it was confirmed that any ink composition can be discharged satisfactorily.
The drawing conditions were as follows.
Inkjet head scan speed: 1 m / s
Base material: UV gloss coat 157 (157 g / cm ² , UVGC760, gloss paper, manufactured by Sakurai Co., Ltd., thickness 150 μm)
Drawing mode: 1,200 dpi × 1,200 dpi, 12 passes Image: 300% halftone gray in 4 colors (yellow, magenta, cyan, black) Relative relationship between head positions of each color: Nozzle arrangement (In this embodiment, this mode is also referred to as “nozzle shifting”).

<Odor evaluation>
4GC image data of C (cyan) = 100, M (magenta) = 100, Y (yellow) = 100, K (black) = 100 is created in Photoshop (manufactured by Adobe Systems), and this image is actually used. It output with the size of 10 cm x 10 cm with a printer. The printing conditions were 600 × 500 dpi, 10-pass, bidirectional printing mode, and output to the coated paper (UV gloss coat 157, manufactured by Sakurai Co., Ltd.). The printed material was cut into A4 size, placed in a plastic bag with a chuck and allowed to stand for 10 minutes, and then the odor when the chuck was opened was evaluated in five stages. The average of 10 people was used for evaluation. The average value is rounded off.
5: I do not feel the odor of the printed matter.
4: Feels a slight odor of the printed matter, but hardly notices it.
3: Although the odor of the printed matter is slightly felt, it is not an unpleasant level.
2: Feel the odor of the printed matter.
1: The odor of the printed matter is strongly felt.

<Migration evaluation>
4GC image data of C = 100, M = 100, Y = 100, K = 100 was created in Photoshop, and this image was output in a size of 10 cm × 10 cm with an actual printer. Printing conditions were output to PET (Viewful TP85) in 600 × 500 dpi, 10-pass, bidirectional printing mode. The printed matter was immersed in a 1/1 solution (volume) of water / methanol for 30 minutes and measured by liquid chromatography (developing solvent: water / methanol = 1/1, differential refractive index (RI) detector). At that time, a standard of 10 ppm (paraoxybenzoic acid ester) was added for measurement.
5: Level where there is no problem when the total peak area detected is 5% or less with respect to the peak area of the internal standard 4: Level where there is no problem when the total peak area detected is 10% or less with respect to the peak area of the internal standard 3: Level that causes no problem when the total peak area to be detected is 15% or less of the peak area of the internal standard 2: Level that causes a slight problem in practical use when the total peak area to be detected is 20% or less of the peak area of the internal standard 1: Level that causes a practical problem when the total peak area detected is 20% or more of the peak area of the internal standard

<Evaluation of image stickiness>
4GC image data of C = 100, M = 100, Y = 100, K = 100 was created in Photoshop, and this image was output in a size of 10 cm × 10 cm with an actual printer. The printing conditions were 600 × 500 dpi, 10-pass, bidirectional printing mode, and output to the coated paper (UV gloss coat 157, manufactured by Sakurai Co., Ltd.). The printed matter was palpated and the stickiness was evaluated.
5: Feels no stickiness on the printed surface 4: Feels slightly sticky on the printed surface, but does not cause any practical problem 3: Feels slightly sticky on the printed surface, but does not cause any practical problem 2: On the printed surface Slightly sticky and practically problematic level 1: Feeling sticky on the printed surface and practically problematic level

<Bending resistance evaluation>
4GC image data of C = 100, M = 100, Y = 100, K = 100 was created in Photoshop, and this image was output in a size of 10 cm × 10 cm with an actual printer. Printing conditions were 600 × 500 dpi, 10-pass, bidirectional printing mode, and output to a polypropylene sheet. The printed matter was grasped with the thumbs of both hands separated by 1 cm, and evaluation was performed by the number of times that the image started to break by gripping once per second.
5: The image was not peeled even after 10 times.
4: The image peeled off 8 to 9 times.
3: The image peeled off 5 to 7 times.
2: The image peeled off 2 to 4 times.
The image peeled off at 1: 1 times.

  The evaluation results in Examples 1 to 29 and Comparative Examples 1 to 7 are summarized in Tables 1 to 4.

  In Tables 1 to 4, the numerical value in the column of “monofunctional ratio (relative to the ink composition)” represents the total content of the monofunctional polymerizable compound with respect to the total mass of the ink composition, and “polyfunctional ratio ( “With respect to the polymerizable compound” ”represents the total content of the polyfunctional polymerizable compound (component A and component C) with respect to the total mass of the polymerizable compound contained in the ink composition, and“ polyfunctional ratio (ink composition). The numerical value in the column “with respect to the product” represents the total content of the polyfunctional polymerizable compound (component A and component C) with respect to the total mass of the ink composition, and the numerical value in the column “preferred polyfunctional ratio” Dodecanediol diacrylate, 3-methyl-1,5-pentanediol diacrylate, trimethylolpropane triacrylate, and ethylene oxide-modified tri with respect to the total mass of the polymerizable compound contained in the ink composition It represents the total content of Chi triacrylate.

  In Example 29, a four-color ink composition of yellow, magenta, cyan and black was used as an ink set to form a full-color image by the same method as described above, and evaluation was performed.

The abbreviations described in Tables 1 to 4 other than those described above are as shown below.
<Polymerizable compound (monomer)>
PEA: 2-phenoxyethyl acrylate, SR339 manufactured by Sartomer Japan
CTFA: cyclic trimethylolpropane formal acrylate (SR531, manufactured by Sartomer Japan, Inc.)
-IBOA: Isobonyl acrylate (IBXA, manufactured by Osaka Organic Chemical Industry Co., Ltd.)
3-methylpentanediol diacrylate: 3-methyl-1,5-pentanediol diacrylate, SR341 manufactured by Sartomer Japan, Inc.
DDDA: 1,12-dodecanediol diacrylate, CD262 manufactured by Sartomer Japan K.K.
TMPTA: trimethylolpropane triacrylate, SR351S manufactured by Sartomer Japan
EOTMPTA: ethoxylated (3) trimethylolpropane triacrylate (a compound obtained by triacrylated trimethylolpropane ethylene oxide 3 mol adduct), SR454 D NS manufactured by Sartomer Japan K.K.
DPGDA: Dipropylene glycol diacrylate, SR508 manufactured by Sartomer Japan, Inc.
HDDA: 1,6-hexanediol diacrylate, SR238 manufactured by Sartomer Japan, Inc.
SR-833: Tricyclodecane dimethanol diacrylate, manufactured by Sartomer Japan, Ltd. SR9003 manufactured by Sartomer Japan
Tetramethylol methane tetraacrylate: pentaerythritol tetraacrylate, A-TMMT manufactured by Shin-Nakamura Chemical Co., Ltd.
・ Dimethylaminopropylacrylamide: 3-dimethylaminopropylacrylamide, manufactured by Kojin Co., Ltd. ・ Hydroxyethylacrylamide: 2-hydroxyethylacrylamide, manufactured by Sigma-Aldrich Japan Co., Ltd. ・ Compound A: Compound synthesized above

<Photopolymerization initiator>
-ESACURE KIP150: The following compound, manufactured by Lamberti-SPEEDCURE BCIM: 2,2'-bis (2-chlorophenyl) -4,4 ', 5,5'-tetraphenyl-1,2'-biimidazole, manufactured by Lambson , Molecular weight 660
SPEEDCURE 7005: 1,3-di ({α-2- (phenylcarbonyl) benzoyl poly [oxy (1-methylethylene)]} oxy) -2,2-bis ({α-2- (phenylcarbonyl) benzoyl Poly [oxy (1-methylethylene)]} oxymethyl) propane and {α-2- (phenylcarbonyl) benzoylpoly (oxyethylene) -poly [oxy (1-methylethylene)]-poly (oxyethylene)} 2 -Mixture with (phenylcarbonyl) benzoate, manufactured by Lambson, molecular weight 1,196
SPEEDCURE 7010: 1,3-di ({α- [1-chloro-9-oxo-9H-thioxanthen-4-yl] oxy} acetylpoly [oxy (1-methylethylene)]) oxy) -2, 2-bis ({α- [1-chloro-9-oxo-9H-thioxanthen-4-yl] oxy} acetylpoly [oxy (1-methylethylene)]) oxymethylpropane, Lambson, molecular weight 1, 899
SPEEDCURE 7040: 1,3-di ({α-4- (dimethylamino) benzoyl poly [oxy (1-methylethylene)]} oxy) -2,2-bis ({α-4- (dimethylamino) benzoyl Poly [oxy (1-methylethylene)]} oxymethyl) propane and {α-4- (dimethylamino) benzoyl poly (oxyethylene) -poly [oxy (1-methylethylene)]-poly (oxyethylene)} 4 -Mixture with (dimethylamino) benzoate, manufactured by Lambson, molecular weight 1,066
IRGACURE 184: 1-hydroxycyclohexyl phenyl ketone, molecular weight 204, manufactured by BASF Japan Ltd. DAROCUR TPO: 2,4,6-trimethylbenzoyldiphenylphosphine oxide, molecular weight 348.4, manufactured by BASF Japan Ltd. IRGACURE 819: Bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide, molecular weight: 418.46, manufactured by BASF Japan Ltd. ITX: isopropylthioxanthone, molecular weight 212, SPEDDCURE ITX manufactured by Lambson

<Polymerization inhibitor>
FIRSTCURE ST-1: Tris (N-nitroso-N-phenylhydroxyamine) aluminum salt, manufactured by Chem First
MEHQ: Hydroquinone monomethyl ether, manufactured by Tokyo Chemical Industry Co., Ltd. TEMPO: 2,2,6,6-tetramethylpiperidinyl 1-oxyl, manufactured by Tokyo Chemical Industry Co., Ltd. OH-TEMPO: 4-hydroxy- 2,2,6,6-tetramethylpiperidine 1-oxyl, 4-HYDROXY TEMPO manufactured by Evonik

<Oligomer>
CN964 A85: urethane acrylate oligomer, average functional group number 2, manufactured by Sartomer Japan KK, weight average molecular weight 1,600-1,800

（式中、ｎは２以上の整数を表し、Ｒは末端基を表す。）

(In the formula, n represents an integer of 2 or more, and R represents a terminal group.)

(Examples 30 to 33)
Each of the inkjet ink compositions of Examples 17 to 20 was used, and the ink pack storage stability was evaluated by the following evaluation method. The ink pack was prepared by filling 50 cc of the ink composition into an aluminum-deposited multilayer structure container (pack) whose innermost layer was polyolefin so that no gas was enclosed. The evaluation results are shown in Table 5.

<Ink pack storage stability evaluation>
Viscosity and pigment particle size immediately after preparation of the ink composition were defined as initial physical properties (reference), and physical properties of the ink composition after 4 weeks at 60 ° C. after preparation of the ink pack were defined as physical properties after aging.
The ink pack storage stability was judged by the following evaluation, where the ink physical property change rate = {(physical properties after time) / (initial physical properties)} × 100.
The viscosity was measured at 25 ° C. using an E-type viscometer. The ink composition after 4 weeks at 60 ° C. was measured by cooling to 25 ° C. The pigment particle diameter was measured using FPAR-1000 (manufactured by Otsuka Electronics Co., Ltd.) using methyl ethyl ketone as a diluent solvent and diluting to an appropriate concentration.
5: Both the viscosity and the pigment particle size have a change rate of 3% or less. 4: Both the viscosity and the pigment particle size have a change rate of 5% or less. 3: Both the viscosity and the pigment particle size have a change rate. Within 10% for both 2: Viscosity and pigment particle size both change within 15% 1: Either or both of the viscosity and pigment particle size change exceeds 15%

  1: LED light source unit, 2: inert gas blanket, 3: inert gas piping, 4: inert gas generator, 5, 5 ′: support winding roll, 6: support, 7: inkjet head unit, 10: inkjet recording apparatus, 12: recording medium, 20: apparatus main body, 22: support leg, 24: inkjet head, 26: platen, 28: guide mechanism, 30: carriage, 32A, 32B: temporary curing light source, 33, 35 : UV-LED element, 34A, 34B: main curing light source, 36: ink cartridge, 38: mounting portion, 40: nip roller, 42: feeding / feeding roll, 44: take-up roller, 46: guide, 50: temperature control portion, 52: pre-temperature control unit, 54: after-temperature control unit, 61: nozzle row, 110: inkjet head, 112: head, 114: Zur

Claims (10)

(Component A) Compound represented by Formula (1),
(Component B) a photopolymerization initiator having a molecular weight of 400 to 2,000, and
(Component C) containing a polyfunctional polymerizable compound other than Component A,
An inkjet ink composition, wherein the total content of component A and component C is 80% by mass or more based on the total mass of the polymerizable compound in the ink composition.

(In the formula (1), R ¹ each independently represent a hydrogen atom or a methyl group, L ¹ each independently represents a linear or branched alkylene group having 2 to 4 carbon atoms, also, L ¹ in not take an oxygen atom and a nitrogen atom bonded to both ends of the L ¹ is bonded to the same carbon atom of L ¹ structure, L ² each independently represents a divalent linking group, k is Each independently represents 2 or 3, x, y, and z each independently represent an integer of 0-6, and x + y + z satisfies 0-18.)   Component C is at least one compound selected from the group consisting of dodecanediol diacrylate, 3-methyl-1,5-pentanediol diacrylate, trimethylolpropane triacrylate, and ethylene oxide-modified trimethylolpropane triacrylate The inkjet ink composition according to claim 1, comprising:   The total content of component C in the ink composition is the total content of dodecanediol diacrylate, 3-methyl-1,5-pentanediol diacrylate, trimethylolpropane triacrylate, and ethylene oxide-modified trimethylolpropane triacrylate. The inkjet ink composition according to claim 2, wherein the amount is 80% by mass or more.   The inkjet ink composition according to any one of claims 1 to 3, wherein the content of component A is 1 to 20 mass% with respect to the total mass of the ink composition.   The inkjet ink composition according to any one of claims 1 to 4, wherein the total content of Component A and Component C is 50% by mass or more based on the total mass of the ink composition.   The inkjet ink composition according to claim 1, wherein the total content of component A and component C is 70% by mass or more based on the total mass of the ink composition.   The monofunctional polymerizable compound is not contained, or the content of the monofunctional polymerizable compound is 10% by mass or less based on the total mass of the ink composition. Inkjet ink composition.   The inkjet ink composition according to any one of claims 1 to 7, wherein Component B is an α-hydroxyketone compound.   The inkjet ink composition according to any one of claims 1 to 8, which is an inkjet ink composition for printing food packages. (A ¹⁾ on a recording medium, a step of discharging the ink composition according to any one of claims 1 to 9 and,
(B ¹ ) A step of irradiating the discharged ink composition with actinic radiation to cure the ink composition.

Images