JP2013040267A - Ink composition, and inkjet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink composition excellent in curability, and to provide an inkjet recording method using the same.SOLUTION: The ink composition contains (component A) a (meth)acrylamide compound represented by formula (1), (component B) a polymerization initiator, and (component C) a colorant. In the formula, Ar is an (m+n)-valent aromatic group; X is an ionic group; R is a group having a (meth)acrylamide group; and m and n are each independently an integer of ≥1.

Description

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

In recent years, paints and inks (hereinafter also referred to as “inks”) are becoming water-based due to increasing needs such as resource protection, environmental conservation, and work stability improvement. As a means for improving the fixability of a printed image obtained with an aqueous ink, for example, an ultraviolet curable aqueous ink has been known for a long time.
As a water-soluble polymerizable compound applicable to such an ultraviolet curable aqueous ink, a polymerizable compound containing a long-chain water-soluble group is known (see, for example, Patent Document 1).
Moreover, a certain acrylamide compound is disclosed as a crosslinkable monomer for forming a biocompatible material (for example, refer nonpatent literature 1).

JP 2007-314610 A

Journal of Polymer Science: Part A: Polymer Chemistry, Vol. 47, 2664-2676 (2009)

However, in the water-based ink described in Patent Document 1, in addition to a decrease in curing sensitivity due to an increase in molecular weight, there are cases where the blocking resistance of the resulting image is decreased due to poor curing.
The present invention has been made in view of the above, and an object of the present invention is to provide an ink composition having excellent curability and an ink jet recording method using the ink composition.

The above-described problems of the present invention have been solved by means described in <1> and <10> below. It is described below together with <2> to <9> and <11>, which are preferred embodiments.
<1> (Component A) An ink composition comprising a (meth) acrylamide compound represented by the following formula (1), (Component B) a polymerization initiator, and (Component C) a colorant. ,

（式（１）中、Ａｒは（ｍ＋ｎ）価の芳香族基を表し、Ｘはイオン性基を表し、Ｒは（メタ）アクリルアミド基を有する基を表し、ｍ及びｎは各々独立に、１以上の整数を表す。）

(In the formula (1), Ar represents an (m + n) -valent aromatic group, X represents an ionic group, R represents a group having a (meth) acrylamide group, and m and n are each independently 1 (It represents the integer above.)

<2> The ink composition according to <1>, wherein X is —COONa, —COOH, or —ONa.
<3> The ink composition according to <1> or <2> above, wherein X is -COONa or -COOH.
<4> (Component D) The ink composition according to any one of <1> to <3>, further containing water;
<5> The ink composition according to any one of the above <1> to <4>, which is for inkjet recording.
<6> The ink composition according to any one of <1> to <5>, wherein the molecular weight of component A is 180 to 800,
<7> The ink composition according to any one of <1> to <6>, wherein Component A is a compound represented by the following formula (2):

（式（２）中、Ｒ¹〜Ｒ⁴は各々独立に、水素原子又はアルキル基を表し、Ｙ¹及びＹ²は各々独立に、単結合又は二価の有機基を表し、Ｘはイオン性基を表し、ｎは１〜４の整数を表す。）

(In the formula (2), the R ¹ to R ⁴ each independently represent a hydrogen atom or an alkyl group, Y ¹ and Y ² each independently represent a single bond or a divalent organic group, X is an ionic Represents a group, and n represents an integer of 1 to 4.)

<8> (Component E) The ink composition according to any one of <1> to <7>, further including a polymerizable compound other than Component A,
<9> The ink composition according to <8>, wherein Component E comprises a monofunctional polymerizable compound,
<10> A discharge step of discharging the ink composition according to the above <4> onto a recording medium, a heating and drying step of evaporating at least water from the ink composition discharged by the heating means, and the discharged ink composition A curing step of curing the ink composition by irradiating active energy rays to the inkjet recording method,
<11> The inkjet recording method according to <10>, further including a treatment liquid application step of applying an acidic treatment liquid on the recording medium before the ejection step.

  According to the present invention, it was possible to provide an ink composition having excellent curability and an ink jet recording method using the ink composition.

Hereinafter, the present invention will be described in detail.
In the specification, the description of “A to B” representing a numerical range is synonymous with “A or more and B or less”. The “(component A) (meth) acrylamide compound represented by the following formula (1)” or the like is also simply referred to as “component A” or the like.

(Ink composition)
The ink composition of the present invention (hereinafter also simply referred to as “ink”) is (Component A) a (meth) acrylamide compound represented by the following formula (1) (hereinafter also referred to as “specific polymerizable compound”). (Component B) a polymerization initiator and (Component C) a colorant.

（式（１）中、Ａｒは（ｍ＋ｎ）価の芳香族基を表し、Ｘはイオン性基を表し、Ｒは（メタ）アクリルアミド基を有する基を表し、ｍ及びｎは各々独立に、１以上の整数を表す。）

(In the formula (1), Ar represents an (m + n) -valent aromatic group, X represents an ionic group, R represents a group having a (meth) acrylamide group, and m and n are each independently 1 (It represents the integer above.)

The ink composition of the present invention contains a specific polymerizable compound and a polymerization initiator. For example, when the ink composition is applied onto a recording medium and then irradiated with active energy rays, the ink composition has excellent curing sensitivity. The ink composition is cured and has excellent curability. Further, since the ink composition of the present invention is excellent in curability, it is further excellent in blocking resistance, solvent resistance, tape adhesion and the like.
Further, the ink composition of the present invention can be suitably used as an ink composition for ink jet recording.

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

（式（１）中、Ａｒは（ｍ＋ｎ）価の芳香族基を表し、Ｘはイオン性基を表し、Ｒは（メタ）アクリルアミド基を有する基を表し、ｍ及びｎは各々独立に、１以上の整数を表す。）

(In the formula (1), Ar represents an (m + n) -valent aromatic group, X represents an ionic group, R represents a group having a (meth) acrylamide group, and m and n are each independently 1 (It represents the integer above.)

Ar in Formula (1) represents an (m + n) -valent aromatic group, and from the viewpoint of curability, an (m + n) -valent hydrocarbon aromatic group having 6 to 10 carbon atoms and an aromatic group having 4 to 8 carbon atoms. It is preferably a group heterocyclic group, more preferably a hydrocarbon aromatic group having 6 to 10 carbon atoms, and further a group obtained by removing (m + n) hydrogen atoms from benzene or naphthalene. A group obtained by removing (m + n) hydrogen atoms from benzene is particularly preferable.
The aromatic ring of the (m + n) -valent aromatic group in Ar may have a substituent and is not particularly limited as long as the effect of the present invention is not significantly impaired. Preferred examples include an aryl group, a halogen atom, an alkoxy group, an aryloxy group, an acyl group, an acyloxy group, an alkoxycarbonyl group, and an aryloxycarbonyl group.
X in Formula (1) represents an ionic group, and from the viewpoint of curability, an ionic group having active hydrogen such as a carboxy group, a hydroxyl group, a phosphonic acid group, a phosphoric acid group, or a sulfonic acid group, or those Preferably, the salt is a carboxy group (—COOH), a carboxy group salt (—COOM, M represents a counter ion, the same applies to the following), or a hydroxyl group salt (—OM). Are more preferable, a carboxy group or a salt of a carboxy group is more preferable, and a salt of a carboxy group is particularly preferable. The counter ion M in forming the salt is preferably an alkali metal ion or an onium ion, more preferably an alkali metal ion, more preferably a sodium ion, a potassium ion, or lithium from the viewpoint of curability. It is more preferable that it is an ion, and it is especially preferable that it is a sodium ion.

R in the formula (1) is not particularly limited as long as it is a group having a (meth) acrylamide group. For example, even if it is a (meth) acrylamide group itself, two or more (meth) acrylamide groups are present It may be a group.
Note that “(meth) acryl” refers to either or both of “acryl” and “methacryl”.
The total carbon number of the group having the (meth) acrylamide group is preferably 3 to 60, more preferably 3 to 40, still more preferably 3 to 20, and more preferably 3 to 10. Is particularly preferred.
The (meth) acrylamide group has a (meth) acrylamide group bonded to one end of a (meth) acrylamide group or a combination of one or more groups selected from the group consisting of an alkylene group and an arylene group. It is preferably a group, more preferably a (meth) acrylamide group or a (meth) acrylamide alkyl group, and even more preferably a (meth) acrylamide group or a (meth) acrylamide methyl group.
M in Formula (1) represents an integer of 1 or more, preferably 1 to 5, more preferably 1 to 3, and particularly preferably 2.
N in Formula (1) represents an integer of 1 or more, preferably 1 to 5, more preferably 1 or 2, and particularly preferably 1.

  The (meth) acrylamide compound represented by the formula (1) is preferably a compound represented by the following formula (1-1) or formula (1-2) from the viewpoint of curability. It is more preferable that it is a compound represented by 1-1).

（式（１−１）及び式（１−２）中、Ｘはイオン性基を表し、Ｒ¹及びＲ²は各々独立に、（メタ）アクリルアミド基又は（メタ）アクリルアミドアルキル基を表し、Ｒ’は、アルキル基、アリール基、ハロゲン原子、アルコキシ基、アリーロキシ基、アシル基、アシルオキシ基、アルコキシカルボニル基又はアリーロキシカルボニル基を表し、ｐ１は１〜５の整数を表し、ｑ１は１〜５の整数を表し、ｒ１は０〜４を表し、ｐ１＋ｑ１＋ｒ１は６以下であり、ｐ２は１〜７の整数を表し、ｑ２は１〜７の整数を表し、ｒ１は０〜６を表し、ｐ２＋ｑ２＋ｒ２は８以下である。）

(In Formula (1-1) and Formula (1-2), X represents an ionic group, R ¹ and R ² each independently represents a (meth) acrylamide group or a (meth) acrylamide alkyl group, R 'Represents an alkyl group, an aryl group, a halogen atom, an alkoxy group, an aryloxy group, an acyl group, an acyloxy group, an alkoxycarbonyl group or an aryloxycarbonyl group, p1 represents an integer of 1 to 5, and q1 represents 1 to 5 R1 represents 0 to 4, p1 + q1 + r1 is 6 or less, p2 represents an integer of 1 to 7, q2 represents an integer of 1 to 7, r1 represents 0 to 6, and p2 + q2 + r2 represents 8 or less.)

X in Formula (1-1) or Formula (1-2) has the same meaning as X in Formula (1), and the preferred embodiment is also the same.
R ¹ in formula (1-1) or R ² in formula (1-2) is preferably a (meth) acrylamide group or a (meth) acrylamide methyl group, and more preferably a (meth) acrylamide group. .
R ′ in Formula (1-1) or Formula (1-2) is preferably an alkyl group, a halogen atom, or an acyl group.
P1 in the formula (1-1) is preferably 1 or 2, and particularly preferably 1.
Q1 in Formula (1-1) is preferably 1 to 3, and particularly preferably 2.
R1 in the formula (1-1) is preferably 0 to 3, more preferably 0 to 2, still more preferably 0 or 1, and particularly preferably 0.
P2 in Formula (1-2) is preferably 1 or 2, and particularly preferably 1.
Q2 in the formula (1-2) is preferably 1 to 4, more preferably 1 to 3, further preferably 1 or 2, and particularly preferably 1.
R2 in Formula (1-2) is preferably 0 to 4, more preferably 0 to 2, still more preferably 0 or 1, and particularly preferably 0.

  The (meth) acrylamide compound represented by the formula (1) is more preferably a compound represented by the following formula (2) from the viewpoint of curability.

（式（２）中、Ｒ¹〜Ｒ⁴は各々独立に、水素原子又はアルキル基を表し、Ｙ¹及びＹ²は各々独立に、単結合又は二価の有機基を表し、Ｘはイオン性基を表し、ｎは１〜４の整数を表す。）

(In the formula (2), the R ¹ to R ⁴ each independently represent a hydrogen atom or an alkyl group, Y ¹ and Y ² each independently represent a single bond or a divalent organic group, X is an ionic Represents a group, and n represents an integer of 1 to 4.)

X in Formula (2) has the same meaning as X in Formula (1), and the preferred embodiment is also the same.
R ^{1 to} R ⁴ in the formula (2) are preferably each independently a hydrogen atom or a methyl group. Moreover, it is preferable that R < ¹ > and R < ² > in Formula (2) is a hydrogen atom.
Y ¹ and Y ² in Formula (2) are each independently preferably a single bond or an alkylene group, more preferably a single bond or an alkylene group having 1 to 8 carbon atoms, and a single bond or a methylene group. More preferably it is.
N in Formula (2) is preferably 1 or 2, and particularly preferably 1.

  Examples of the specific polymerizable compound that can be suitably used in the ink composition of the present invention are shown below. In the chemical formula below, Ph represents a phenyl group.

  These specific polymerizable compounds can be synthesized by known synthesis methods described in JP-A-11-92435, JP-A-4-351626, US Pat. No. 3,627,831, and the like.

  The content of component A in the ink composition of the present invention is preferably in the range of 1 to 50% by weight, more preferably in the range of 1 to 40% by weight, and in the range of 1 to 30% by weight in terms of solid content. % Is more preferable. The “solid content” in the ink composition of the present invention represents all remaining components excluding water and organic solvent.

(Component B) Polymerization Initiator The ink composition of the present invention contains (Component B) at least one polymerization initiator.
As the polymerization initiator, a known polymerization initiator can be used without particular limitation. As the polymerization initiator in the present invention, it is preferable to use a photopolymerization initiator.
Preferred photopolymerization initiators that can be used in the present invention include (a) aromatic ketones, (b) acylphosphine compounds, (c) aromatic onium salt compounds, (d) organic peroxides, (e) thios. Compound, (f) hexaarylbiimidazole compound, (g) ketoxime ester compound, (h) borate compound, (i) azinium compound, (j) metallocene compound, (k) active ester compound, (l) carbon halogen bond And (m) an alkylamine compound.
Specific examples of the polymerization initiator include, for example, polymerization initiators described on pages 65 to 148 of “Ultraviolet curing system” written by Kiyosuke Kato (published by General Technology Center Co., Ltd .: 1989). Can do.

  As the polymerization initiator in the present invention, either a water-insoluble initiator dispersed in water or a water-soluble initiator can be used, but a water-soluble polymerization initiator is preferable. The water solubility in the polymerization initiator means that it is dissolved in distilled water at 25 ° C. in an amount of 0.5% by weight or more. The water-soluble polymerization initiator is preferably dissolved in distilled water at 25 ° C. at 1% by weight or more, more preferably 3% by weight or more.

  In the present invention, it is preferable to use a polymerization initiator selected from the group consisting of α-hydroxyketones, α-aminoketones and acylphosphine oxides. Specifically, 1- [4- (2-hydroxyethyl) -phenyl] -2-hydroxy-2-methyl] -1-propan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2- A water-soluble polymerization initiator such as methyl-1-phenylpropan-1-one or a non-aqueous polymerization initiator of bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide can be preferably used.

In this invention, a polymerization initiator may be used individually by 1 type, and may use 2 or more types together.
The content of the polymerization initiator in the ink composition of the present invention is preferably in the range of 0.1 to 30% by weight in terms of solid content, more preferably in the range of 0.5 to 20% by weight, More preferably, it is in the range of 1.0 to 15 wt%.
Further, the content of the polymerization initiator in the ink composition of the present invention is preferably 0.01 to 35 parts by weight, and 0.1 to 30 parts by weight with respect to 100 parts by weight of the polymerizable compound. It is more preferable that the amount is 0.5 to 30 parts by weight. Here, the content of the polymerization initiator means the total content of the polymerization initiator in the ink composition, and the content of the polymerizable compound means the polymerizable compound (the specific polymerizable compound and the polymerizable compound in the ink composition). It means the total content of other polymerizable compounds contained as necessary.

(Component C) Colorant The ink composition of the present invention contains (Component C) a colorant.
There is no restriction | limiting in particular as a coloring agent which can be used for this invention, It can select from well-known color materials, such as a pigment, a water-soluble dye, a disperse dye, and can use it. Among these, as a coloring material, it is more preferable that a pigment is included.

<Pigment>
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 and surfaces Treated pigments (for example, pigments dispersed in water, liquid organic compounds or insoluble resins, and pigment surfaces treated with resins, pigment derivatives, etc.) are also included. Examples of the pigment include, for example, “The Pigment Dictionary” edited by Seijiro Ito (2000, published by Asakura Shoten), Isao Hashimoto “Organic Pigment Handbook” (2006, published by Color Office), Herbst, K.M. Hunger, “Industrial Organic Pigments” (published by Wiley-VHC in 1992), JP 2002-12607, JP 2002-188025, JP 2003-26978, JP 2003-342503, JP Examples described in Japanese Unexamined Patent Publication No. 2009-235370.

Examples of the organic pigment and the inorganic pigment include a yellow pigment, a red pigment, a magenta pigment, a blue pigment, a cyan pigment, a green pigment, an orange pigment, a purple pigment, a brown pigment, a black pigment, and a white pigment.
Examples of the yellow pigment include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 10, 65, 73, 74, 75, 97, 98, 111, 116, 130, 167, 205, monoazo pigments, 61, 62, 100, 168, 169, Monoazo lake pigments such as 183, 191, 206, 209, 212, 12, 13, 14, 16, 17, 55, 63, 77, 81, 83, 106, 124, 126, 127, 152, 155, 170, 172, Disazo pigments such as 174, 176, 214 and 219, anthraquinone pigments such as 24, 99, 108, 193 and 199, monoazopyrazolone pigments such as 60, condensed azo pigments such as 93, 95, 128 and 166, 109, 110, 139, 173, 185 and other isoindoline pigments, 120, 151, 154, 175, 180, 181, 194 and other benz Izoazolone pigments, azomethine metal complex pigments such as 117, 129, 150 and 153, quinophthalone pigments such as 138, and quinoxaline pigments such as 213 are preferred.

  Examples of the red or magenta pigment include C.I. I. Pigment Red 193 and other monoazo lake pigments, 38 and other disazo pigments, 2, 5, 8, 9, 10, 11, 12, 14, 15, 16, 17, 18, 22, 23, 31, 32, 112, 114, Naphthol AS pigments such as 146, 147, 150, 170, 184, 187, 188, 210, 213, 238, 245, 253, 256, 258, 266, 268, 269, etc. β-naphthol pigments such as 3, 4, 6, etc. , 49, 53, 68 etc. β-naphthol lake pigments, 237, 239, 247 etc. naphthol AS lake pigments, 41 etc. pyrazolone pigments, 48, 52, 57, 58, 63, 64: 1, 200 etc. BONA Lake pigments, xanthene lake pigments such as 81: 1, 169, 172, thioindigo pigments such as 88, 181, 279, 123, 149, 1 8, 179, 190, 224 etc. perylene pigment, 144, 166, 214, 220, 221, 242, 262 etc. condensed azo pigment, 168, 177, 182, 226, 263 etc. anthraquinone pigment, 83 etc. anthraquinone lake Pigments, benzimidazolone pigments such as 171, 175, 176, 185, 208, quinacridone pigments such as 122, 202 (including mixtures with CI Pigment Violet 19), 207, 209, 254, 255, 264, Diketopyrrolopyrrole pigments such as 270 and 272 are preferred, and azomethine metal complex pigments such as 257 and 271 are preferred.

Examples of the blue or cyan pigment include C.I. I. Naphthol AS pigments such as CI Pigment Blue 25 and 26, phthalocyanine pigments such as 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 17: 1, 75, and 79 Dye lake pigments such as 1:56, 61, 62, anthraquinone pigments such as 60, indigo pigments such as 63, and dioxazine pigments such as 80 are preferable.
Examples of the green pigment include C.I. I. Dye lake pigments such as CI Pigment Green 1 and 4, phthalocyanine pigments such as 7 and 36, and azomethine metal complex pigments such as 8 are preferable.
Examples of the orange pigment include C.I. I. Monoazo pigments such as CI Pigment Orange 1, β-naphthol pigments such as 2, 3, 5 and the like, naphthol AS pigments such as 4, 24, 38 and 74, pyrazolone pigments such as 13, 34, 36, 60, 62, 64 and 72 Benzimidazolone pigments such as 15 and 16; β-naphthol lake pigments such as 17 and 46; naphthalenesulfonic acid lake pigments such as 19; perinone pigments such as 43; quinacridone pigments such as 48 and 49; Anthraquinone pigments such as 61, isoindolinone pigments such as 61, isoindoline pigments such as 66, azomethine metal complex pigments such as 68, and diketopyrrolopyrrole pigments such as 71, 73 and 81 are preferred.

Examples of the brown pigment include C.I. I. BONA lake pigments such as CI Pigment Brown 5, condensed azo pigments such as 23, 41 and 42, and benzimidazolone pigments such as 25 and 32 are preferred.
Examples of the purple pigment include C.I. I. Pigment violet 1, 2, 3, 27 etc. dyed lake pigments, 13, 17, 25, 50 etc. naphthol AS pigments, 5: 1 etc. anthraquinone lake pigments, 19 etc. quinacridone pigments, 23, 37 etc. dioxazine pigments A perylene pigment such as No. 29, benzimidazolone pigment such as No. 32, and a thioindigo pigment such as No. 38 are preferred.
Examples of the black pigment include C.I. I. Indazine pigments such as CI pigment black 1, carbon black as 7, graphite as 10, magnetite as 11, anthraquinone pigment as 20 and perylene pigment as 31 and 32 are preferable.
Examples of the white pigment include C.I. I. Pigment White 4 Zinc oxide, 6 Titanium oxide, 7 Zinc sulfide, 12 Zirconium oxide (zirconium white), 18 Calcium carbonate, 19 Aluminum oxide / silicon oxide (Kaolin clay), 21 Or the barium sulfate which is 22, the aluminum hydroxide (alumina white) which is 23, the silicon oxide which is 27, and the calcium silicate which is 28 are preferable.
The inorganic particles used in the white pigment may be simple substances, or may be oxides such as silicon, aluminum, zirconium, and titanium, organometallic compounds, and composite particles with organic compounds.
Among these, the titanium oxide 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.

  Pigment particles, dispersants, and media so that the volume average particle diameter of the pigment particles is preferably 0.005 to 0.5 μm, more preferably 0.01 to 0.45 μm, and still more preferably 0.015 to 0.4 μm. Selection, dispersion conditions, and filtration conditions are preferably set. In the present invention, the average particle size and particle size distribution of the particles are determined by dynamic light scattering using a commercially available particle size measuring device such as Nanotrack particle size distribution measuring device UPA-EX150 (manufactured by Nikkiso Co., Ltd.). It is obtained by measuring the volume average particle diameter by the method.

<Water-soluble dye>
Examples of water-soluble dyes that can be used in the present invention include acid dyes and direct dyes. Acid dyes and direct dyes have a structure having an acid group as a solubilizing group. Examples of acidic groups include sulfonic acid groups and salts thereof, carboxylic acid groups and salts thereof, phosphoric acid groups and salts thereof. The number of acidic groups may be one or more, and a plurality of types may be combined. The chemical structure of the chromophore contained in the water-soluble dye includes azo, phthalocyanine, triphenylmethane, xanthene, pyrazolone, nitro, stilbene, quinoline, methine, thiazole, quinoneimine, and indigoid. Type, rhodamine type, anthraquinone type, anthraquinone type and the like.

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

The colorant that can be used in the present invention may be used alone or in combination of two or more.
The content of the colorant in the ink composition of the present invention is appropriately selected depending on the physical properties of the colorant (specific gravity, coloring power, color, etc.), and how many colors of the ink composition are combined to produce a printed matter. However, it is preferably 0.1 to 30% by weight and more preferably 0.5 to 20% by weight with respect to the weight of the entire ink composition.

<Pigment dispersant>
When a pigment is used as the colorant, a pigment dispersant may be used as necessary when preparing the pigment particles.
Examples of the pigment dispersant that can be used in the present invention include higher fatty acid salts, alkyl sulfates, alkyl ester sulfates, alkyl sulfonates, sulfosuccinates, naphthalene sulfonates, alkyl phosphates, and polyoxyalkylenes. Activators such as alkyl ether phosphate, polyoxyalkylene alkyl phenyl ether, polyoxyethylene polyoxypropylene glycol, glycerin ester, sorbitan ester, polyoxyethylene fatty acid amide, amine oxide, or styrene, styrene derivative, vinyl naphthalene derivative, Block copolymer consisting of two or more monomers selected from the group consisting of acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid, and fumaric acid derivatives Body, may be mentioned random copolymers and salts thereof.

A self-dispersing pigment can also be used in the ink composition of the present invention. The self-dispersing pigment referred to in the present invention refers to a pigment that can be dispersed without a pigment dispersant, and particularly preferably pigment particles having a polar group on the surface.
The pigment particles having a polar group on the surface in the present invention are a pigment that is directly modified with a polar group on the surface of the pigment particle, or an organic substance having an organic pigment mother nucleus, or the polar group is bonded directly or through a joint. (Hereinafter also referred to as “pigment derivative”).
Examples of the polar group include a sulfonic acid group, a carboxylic acid group, a phosphoric acid group, a boric acid group, and a hydroxyl group, and a sulfonic acid group and a carboxylic acid group are preferable, and a sulfonic acid group is more preferable.
In order to obtain such pigment particles having a polar group on the surface, known methods can be used as appropriate.
The polar group on the pigment surface may be free or in a salt state, or may have a counter salt. Examples of the counter salt include inorganic salts (lithium, sodium, potassium, magnesium, calcium, aluminum, nickel, ammonium) and organic salts (triethylammonium, diethylammonium, pyridinium, triethanolammonium, etc.), preferably 1 A counter salt having a valence.

As a method for dispersing the pigment, for example, various dispersing machines such as a ball mill, a sand mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, and a paint shaker can be used. It is also preferable to use a centrifugal separator or a filter for the purpose of removing the coarse particles of the pigment dispersion.
The preferred addition amount of the dispersant in the ink composition is such that the weight ratio (D / P) is P where the weight of the pigment in the ink composition is P and the weight of the polymer dispersant in the ink composition is D. 0.01 ≦ D / P ≦ 2.0 is preferable, 0.03 ≦ D / P ≦ 1.5 is more preferable, and 0.05 ≦ D / P ≦ 0.6 is satisfied. Is more preferable.
Further, at the time of dispersion, in addition to the dispersant, a dispersion aid generally called synergist (for example, SOLPERSE series 5000, 12000, 22000, commercially available from Lubrizol, EFKA6745, commercially available from BASF Japan), etc. It is also preferred to improve the dispersibility and wettability of the pigment by adding various surfactants and antifoaming agents.

In the present invention, when the pigment is dispersed, the pigment and the dispersant are mixed and then added to the polar organic solvent and dispersed, or the polar organic solvent and the dispersant are mixed and then the pigment is added. And dispersing. For the dispersion, for example, dispersion devices such as a ball mill, a bead mill, a sand mill, a salt mill, an attritor, a roll mill, an agitator, a Henschel mixer, a colloid mill, an ultrasonic homogenizer, a pearl mill, a wet jet mill, and a paint shaker can be used. Among these, a bead mill dispersing device is preferable because of its excellent dispersibility.
The beads used for the bead mill dispersion are preferably those having a volume average diameter of 0.01 to 3.0 mm, more preferably 0.05 to 1.5 mm, and still more preferably 0.1 to 1.0 mm. By using it, a pigment dispersion excellent in stability can be obtained.
In the present invention, the colorants may be used alone or in combination of two or more.

(Component D) Water The ink composition of the present invention preferably contains (Component D) water. The ink composition of the present invention is preferably a water-based ink composition.
As water in this invention, it is preferable to use water which does not contain ionic impurities, such as ion-exchange water and distilled water.
Further, the water content in the ink composition of the present invention is appropriately selected according to the purpose, but is preferably 10 to 95% by weight, and more preferably 30 to 90% by weight.

(Component E) Polymerizable compound other than Component A In the ink composition of the present invention, a polymerizable compound other than Component A (hereinafter also referred to as “other polymerizable compound”) within a range not impairing the effects of the present invention. ) May be included.
The other polymerizable compound is a polymerizable compound having an ethylenically unsaturated bond capable of radical polymerization, and having at least one ethylenically unsaturated bond capable of radical polymerization in the molecule, the specific polymerization Any compound may be used as long as it is a compound other than a chemical compound, and includes compounds having chemical forms such as monomers, oligomers, and polymers.
Moreover, only 1 type may be used for another polymeric compound, and 2 or more types may be used together by arbitrary ratios in order to improve the target characteristic.

Examples of the polymerizable compound having an ethylenically unsaturated bond include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, and salts or derivatives thereof, ethylenically unsaturated groups And radically polymerizable compounds such as unsaturated acrylonitrile, styrene, various unsaturated polyesters, unsaturated polyethers, unsaturated polyamides, and unsaturated urethanes.
Specifically, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, butoxyethyl acrylate, carbitol acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, benzyl acrylate, bis (4-acryloxypolyethoxyphenyl) propane, neopentyl glycol Diacrylate, 1,6-hexanediol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol diacrylate, polypropylene glycol diacrylate, pentaerythritol triacrylate, pentaerythritol Tetraacrylate, dipentaery Litol tetraacrylate, trimethylolpropane triacrylate, tetramethylolmethane tetraacrylate, oligoester acrylate, N, N-dimethylaminoacrylamide, N, N-dimethylaminoethylacrylamide, N, N-dimethylaminopropylacrylamide, and these A quaternized compound of N-methylolacrylamide, hydroxyethylacrylamide, hydroxypropylacrylamide, 4-acryloylmorpholine, N- [1,1-dimethyl-2- (sodiooxysulfonyl) ethyl] acrylamide, diacetoneacrylamide, Acrylic acid derivatives such as epoxy acrylate, methyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate , Allyl methacrylate, glycidyl methacrylate, benzyl methacrylate, dimethylaminomethyl methacrylate, 1,6-hexanediol dimethacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, trimethylolethane Trimethacrylate, trimethylolpropane trimethacrylate, 2,2-bis (4-methacryloxypolyethoxyphenyl) propane, N, N-dimethylamino (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylamide, N, Methacrylic acid derivatives such as N-dimethylaminopropyl (meth) acrylamide, other, allyl glycidyl ether , Derivatives of allyl compounds such as diallyl phthalate and triallyl trimellitate.
Among these, from the viewpoint of ejection stability of the ink composition, a polymerizable compound having a water-soluble ethylenically unsaturated bond is preferable. In addition, water solubility here is synonymous with the water solubility in the said specific polymerizable compound.

Examples of the polymerizable compound having a water-soluble ethylenically unsaturated bond are preferably at least one selected from acrylic acid and methacrylic acid, and ester derivatives, amide derivatives and salts thereof, and monoesters of acrylic acid and Methacrylic acid monoester (hereinafter, also referred to as “monoacrylate”), ester of acrylic acid and polyol compound, and ester of methacrylic acid and polyol compound (hereinafter “polyfunctional acrylate monomer” or “polyfunctional acrylate oligomer”) Also acrylamide, methacrylamide and derivatives thereof.
From the viewpoint of imparting water solubility, the polymerizable compound having a water-soluble ethylenically unsaturated bond used in the present invention has a poly (ethyleneoxy) chain, a poly (propyleneoxy) chain, an ionic group (for example, a carboxyl group, a sulfo group). Group) and at least one hydroxyl group.
When the polymerizable compound having a water-soluble ethylenically unsaturated bond has a poly (ethyleneoxy) chain and a poly (propyleneoxy) chain, the number of units of ethyleneoxy units and propyleneoxy units is 1 to A range of 10 is preferable, and a range of 1 to 5 is more preferable. When the number of units is 10 or less, the hardness of the film when cured and the adhesion to the recording medium are improved.

The other polymerizable compound is preferably a monofunctional or bifunctional polymerizable compound and more preferably a monofunctional polymerizable compound from the viewpoints of curability and blocking resistance.
The monofunctional polymerizable compound is preferably an acrylamide compound or a methacrylamide compound, more preferably an acrylamide compound, and particularly preferably 2-hydroxyethylacrylamide.

The content of the other polymerizable compound in the ink composition of the present invention is preferably in the range of 0.1 to 50% by weight, and in the range of 0.5 to 40% by weight in terms of solid content. More preferably, it is still more preferably in the range of 1.0 to 30% by weight.
The content of the other polymerizable compound relative to the specific polymerizable compound is preferably in the range of 0 to 80% by weight, more preferably in the range of 0 to 70% by weight in terms of solid content. More preferably, it is in the range of 0 to 60% by weight.

<Other additives>
In the ink composition of the present invention, in addition to the specific polymerizable compound, the polymerization initiator, and the colorant that are essential components, and water, other polymerizable compounds, and the pigment dispersant that are optional components, As long as the effects of the present invention are not impaired, known additives can be used in combination. Hereinafter, additives that can be used in the ink composition will be described.

(Water-soluble organic solvent)
The ink composition of the present invention is preferably a water-based ink composition containing water, and it is preferable to further use a water-soluble organic solvent in accordance with the purpose.
Here, the water-soluble organic solvent means an organic solvent having a solubility in water at 25 ° C. of 10% by weight or more.
Examples of water-soluble organic solvents that can be used in the present invention include the following.
Alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexanol, benzyl alcohol, etc.),
Polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol, 2- Methylpropanediol, etc.)
Polyhydric alcohol ethers (for example, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, tripropylene Oligoalkylene glycol monoalkyl ether, such as glycol monomethyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, or the like such as dipropylene glycol dimethyl ether. Alkylene glycol dialkyl ether, ethylene glycol monomethyl ether acetate, ethylene glycol monophenyl ether, propylene glycol monophenyl ether, etc.),
-Amines (eg, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentane Methyldiethylenetriamine, tetramethylpropylenediamine, etc.),
Amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.),
Heterocycles (eg, ethylene carbonate, propylene carbonate, 3-methyl-2-oxazolidinone, 3-ethyl-2-oxazolidinone, 3-propyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone, 2 -Pyrrolidone, 1-methyl-2-pyrrolidone, γ-butyrolactone, etc.),
・ Sulphoxides (for example, dimethyl sulfoxide),
-Sulfones (for example, sulfolane),
・ Others (urea, acetonitrile, acetone, etc.)

Preferred examples of the water-soluble organic solvent include heterocyclic rings and polyhydric alcohol ethers, and it is preferable to use these in combination.
Specific examples of preferred organic solvents include ethylene carbonate, propylene carbonate, 3-methyl-2-oxazolidinone, 3-ethyl-2-oxazolidinone, 3-propyl-2-oxazolidinone, 1,3-dimethyl-2-imidazolidinone. , 2-pyrrolidone, 1-methyl-2-pyrrolidone, γ-butyrolactone and the like. However, the present invention is not limited to these.
As the heterocyclic ring, 2-pyrrolidone, γ-butyrolactone and the like are preferable, and 2-pyrrolidone is particularly preferable. A solvent having a particularly high boiling point can be preferably used, and the boiling point at normal pressure is preferably 120 ° C. or higher, more preferably 150 ° C. or higher.
Among the polyhydric alcohol ethers, so-called glycol ethers are preferable. Specific examples of glycol ethers include oligoalkylene glycol monoalkyl ethers, oligoalkylene glycol dialkyl ethers, tripropylene glycol monomethyl ether, dipropylene glycol monomethyl ether, and dipropylene glycol dimethyl ether are more preferred. Propylene glycol monomethyl ether is particularly preferred.
The water-soluble organic solvent may be used alone or in combination of two or more.
The addition amount of the water-soluble organic solvent in the ink composition is preferably 0.1 to 60% by weight, more preferably 0.5 to 40% by weight, based on the total weight of the ink composition. .

[Surfactant]
A surfactant can be added to the ink composition of the present invention.
As surfactants preferably used, anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalenesulfonates, fatty acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, acetylene glycols, Nonionic surfactants such as polyoxyethylene / polyoxypropylene block copolymers, and cationic surfactants such as alkylamine salts and quaternary ammonium salts. In particular, an anionic surfactant and a nonionic surfactant can be preferably used.
In the present invention, a polymer surfactant can also be used, and the following water-soluble resins are mentioned as preferred polymer surfactants. As the water-soluble resin, styrene-acrylic acid-acrylic acid alkyl ester copolymer, styrene-acrylic acid copolymer, styrene-maleic acid-acrylic acid alkyl ester copolymer, styrene-maleic acid copolymer are preferably used. Polymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-methacrylic acid copolymer, styrene-maleic acid half ester copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer Etc.
In the case where the ink composition of the present invention contains a surfactant, the content of the surfactant in the ink composition of the present invention is not particularly limited, but is 0.01 to about the total weight of the ink composition. It is preferably 10% by weight, more preferably 0.05 to 5% by weight, and still more preferably 0.1 to 3% by weight.

〔latex〕
Latex can be added to the ink composition of the present invention.
Examples of the latex that can be used in the present invention include styrene-butadiene copolymer, polystyrene, acrylonitrile-butadiene copolymer, acrylate copolymer, polyurethane, silicon-acrylic copolymer, and acrylic-modified fluororesin. Of latex. The latex may be a polymer particle dispersed using an emulsifier, or a so-called soap-free latex dispersed without using an emulsifier. A surfactant is often used as an emulsifier, but a polymer having a water-soluble group such as a sulfonic acid group or a carboxylic acid group (for example, a polymer in which a solubilizing group is graft-bonded, a single group having a solubilizing group) It is also preferable to use a polymer obtained from a monomer and a monomer having an insoluble part.
When the ink composition of the present invention contains a latex, the content of the latex in the ink composition of the present invention is not particularly limited, but is 0.1 to 20% by weight with respect to the total weight of the ink composition. Preferably, 0.1 to 20 weight% is more preferable, and 0.1 to 15 weight% is still more preferable.

[Aqueous polymer]
An aqueous polymer can be added to the ink composition of the present invention.
Preferred examples of the aqueous polymer include natural polymers. Specific examples thereof include proteins such as glue, gelatin, casein or albumin, natural rubbers such as gum arabic or tragacanth, glucosides such as saponin, alginic acid. And alginic acid derivatives such as propylene glycol alginate, triethanolamine alginate or ammonium alginate, and cellulose derivatives such as methylcellulose, carboxymethylcellulose, hydroxyethylcellulose or ethylhydroxylcellulose.

  Other preferable examples of the aqueous polymer include synthetic polymers such as polyvinyl alcohols, polyvinylpyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymer, potassium acrylate-acrylonitrile copolymer, Acrylic resin such as vinyl acetate-acrylic acid ester copolymer or acrylic acid-acrylic acid ester copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid ester Styrene acrylic resin such as copolymer, styrene-α-methylstyrene-acrylic acid copolymer, or styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymer, styrene-maleic acid copolymer, styrene -Maleic anhydride copolymer, vinyl naphth Talen-acrylic acid copolymer, vinylnaphthalene-maleic acid copolymer, and vinyl acetate-ethylene copolymer, vinyl acetate-fatty acid vinylethylene copolymer, vinyl acetate-maleic acid ester copolymer, vinyl acetate- Examples thereof include vinyl acetate copolymers such as crotonic acid copolymers and vinyl acetate-acrylic acid copolymers, and salts thereof. Of these, nonionic aqueous polymers are preferred, and particularly preferred examples include polyvinylpyrrolidones.

The weight average molecular weight of the aqueous polymer that can be used in the present invention is preferably 1,000 or more and 200,000 or less. Furthermore, 3,000 or more and 20,000 or less are more preferable.
The amount of the aqueous polymer added is preferably 10% by weight or more and 1,000% by weight or less, and more preferably 50% by weight or more and 200% by weight or less with respect to the dissolved pigment.

[Sensitizer]
The ink composition of the present invention may contain a sensitizer.
In the present invention, known sensitizers can be used in combination.
The solubility in the sensitizer is preferably 0.5% by weight or more, more preferably 1% by weight or more, more preferably 3% by weight or more in distilled water at room temperature (25 ° C.). Those are particularly preferred. As the sensitizer, a polymerization initiator in which a water-insoluble polymerization initiator is dispersed can also be used.
Examples of sensitizers include N- [2-hydroxy-3- (3,4-dimethyl-9-oxo-9H-thioxanthen-2-yloxy) propyl] -N, N, N-trimethylaluminum chloride, Benzophenone, thioxanthone, anthraquinone derivatives and 3-acylcoumarin derivatives, terphenyl, styryl ketone and 3- (aroylmethylene) thiazoline, camphorquinone, eosin, rhodamine and erythrosine, and modified products and dispersions obtained by solubilizing them Can be mentioned. Further, sensitizing dyes described in JP2010-24276A and sensitizing dyes described in JP-A-6-107718 can be suitably used.
When the ink composition of the present invention contains a sensitizer, the latex content in the ink composition of the present invention is not particularly limited, but is 0.05 to 30% by weight in terms of solid content of the ink composition. Is preferable, 0.1 to 20% by weight is more preferable, and 0.2 to 10% by weight is further preferable.

In addition to the above-described components, the ink composition of the present invention may be used for the purpose of improving ejection stability, print head and ink cartridge compatibility, storage stability, image storage stability, and other various performances as necessary. According to various known additives, for example, viscosity modifiers, surface tension modifiers, specific resistance modifiers, film forming agents, ultraviolet absorbers, antioxidants, anti-fading agents, antifouling agents, rust preventives, solids A wetting agent, silica fine particles and the like can be appropriately selected and used.
For example, liquid paraffin, dioctyl phthalate, tricresyl phosphate, oil droplets such as silicone oil, ultraviolet absorbers described in JP-A-57-74193, 57-87988 and 62-261476, Anti-fading agents described in JP-A-57-74192, JP-A-57-87989, JP-A-60-72785, JP-A-61-146591, JP-A-1-95091 and JP-A-3-13376 , JP-A-59-42993, JP-A-59-52689, JP-A-62-280069, JP-A-61-228771, JP-A-4-219266, and the like. Examples thereof include pH adjusters such as acid, citric acid, sodium hydroxide, potassium hydroxide and potassium carbonate.

<Method for Preparing Ink Composition>
The method for preparing the ink composition of the present invention is not particularly limited, and each component is mixed with a container drive medium mill such as a ball mill, a centrifugal mill or a planetary ball mill, a high-speed rotating mill such as a sand mill, or a medium agitation such as a stirring tank mill. It can be prepared by stirring, mixing and dispersing with a simple disperser such as a mill or a disper. About the addition order of each component, it is arbitrary. For example, it can be uniformly mixed with a simple stirrer such as a three-one motor, a magnetic stirrer, a disper, or a homogenizer at or after the addition. You may mix using mixers, such as a line mixer. Further, in order to make the dispersed particles finer, they may be mixed using a dispersing machine such as a bead mill or a high-pressure jet mill. Depending on the type of pigment or polymer dispersant, a resin may be added during premixing before pigment dispersion.

  The ink composition of the present invention preferably has a surface tension at 25 ° C. of 20 to 40 mN / m. The surface tension is measured under the condition of 25 ° C. using an Automatic Surface Tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.). Moreover, 1-40 mPa * s is preferable and, as for a viscosity, 3-30 mPa * s is more preferable. The viscosity of the ink composition is measured using a VISCOMETER TV-22 (manufactured by TOKI SANGYO CO. LTD) at 25 ° C.

<< Image Forming Method and Inkjet Recording Method >>
The image forming method of the present invention includes an ink application step of applying the ink composition of the present invention onto a recording medium, and an ink composition provided with water and a water-soluble organic solvent used together as necessary by a heating means. It includes a heat drying step for evaporating and an irradiation step for irradiating the ink composition with active energy rays. By performing these steps, an image of the ink composition fixed on the recording medium is formed. The application in the application process is preferably performed by an inkjet method.
Further, the ink jet recording method of the present invention includes a discharge step of discharging the ink composition of the present invention onto a recording medium, an ink composition in which water and a water-soluble organic solvent used together as necessary are discharged by a heating means. A heating and drying step of evaporating, and an irradiation step of irradiating the discharged ink composition with active energy rays to cure the ink composition.

<Ink application process and ejection process>
Hereinafter, the ink application process in the image forming method of the present invention and the ejection process in the ink jet recording method of the present invention will be described.
The ink application process in the present invention is not particularly limited as long as it is a process of applying the ink composition onto a recording medium.
The ink jet recording method of the present invention preferably includes a discharge step of discharging the ink composition of the present invention onto a recording medium.
The ink jet recording apparatus used in the image forming method of the present invention and the ink jet recording method of the present invention is not particularly limited, and a known ink jet recording apparatus capable of achieving a desired resolution can be arbitrarily selected and used. it can. That is, any known inkjet recording apparatus including a commercially available product can discharge the ink composition onto the recording medium in the image forming method of the present invention.
Examples of the ink jet recording apparatus that can be used in the present invention include an apparatus including an ink supply system, a temperature sensor, and a heating unit.
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, a piezo-type or a thermal-type inkjet head. The piezo-type or thermal-type ink jet head is preferably 1 to 100 pl, more preferably 8 to 30 pl, multi-size dots, preferably 320 × 320 to 4,000 × 4,000 dpi, more preferably 400 × 400 to 1. , 600 × 1,600 dpi, more preferably 720 × 720 dpi. In the present invention, dpi represents the number of dots per 2.54 cm.

In the ink composition of the present invention, it is desirable that the ejected ink composition is kept at a constant temperature. Therefore, the ink jet recording apparatus is preferably provided with means for stabilizing the ink composition 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 thermal energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

Using the above-described ink jet recording apparatus, the ink composition is ejected by heating the ink composition to preferably 25 to 80 ° C., more preferably 25 to 50 ° C., so that the viscosity of the ink composition is preferably 3 to 15 mPa. It is preferable to carry out after lowering to s, more preferably 3 to 13 mPa · s. In particular, it is preferable to use an ink composition having a viscosity of 50 mPa · s or less at 25 ° C. as the ink composition of the present invention, since it can be discharged satisfactorily. By using this method, high ejection stability can be realized.
The temperature of the ink composition at the time of ejection is preferably constant, and the control range of the temperature of the ink composition is more preferably ± 5 ° C. of the set temperature, further preferably ± 2 ° C. of the set temperature, particularly preferably set. A temperature of ± 1 ° C. is appropriate.

  In the present invention, the recording medium is not particularly limited, and a known recording medium can be used as a support or a recording material. Examples of the recording medium include paper, paper laminated with plastic (eg, polyethylene, polypropylene, polystyrene, etc.), metal plate (eg, aluminum, zinc, copper, etc.), plastic film (eg, polyvinyl chloride resin, two Cellulose acetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, polyethylene terephthalate, polyethylene, polystyrene, polypropylene, polycarbonate, polyvinyl acetal, etc.), paper or plastic on which the above metals are laminated or deposited A film etc. are mentioned. Among them, since the ink composition of the present invention is excellent in adhesion, it can be suitably used for a non-absorbent recording medium as a recording medium, and a plastic substrate such as polyvinyl chloride, polyethylene terephthalate, polyethylene is preferable, A polyvinyl chloride resin base material is more preferable, and a polyvinyl chloride resin sheet or film is still more preferable.

  On the other hand, when processing a support or a recording material with a processing liquid described later, a general printing paper mainly composed of cellulose, such as so-called high-quality paper, coated paper, and art paper, is used for general offset printing. be able to. General printing paper mainly composed of cellulose is relatively slow in ink absorption and drying in image recording by a general ink jet method using water-based ink, and color material movement is likely to occur after droplet ejection, and image quality is likely to deteriorate. However, according to the inkjet recording method of the present invention, it is possible to record a high quality image excellent in color density and hue by suppressing the movement of the colorant.

  As the recording medium, commercially available media can be used. For example, “OK Prince Quality” manufactured by Oji Paper Co., Ltd., “Shiorai” manufactured by Nippon Paper Industries Co., Ltd., and Nippon Paper Industries Co., Ltd. High quality paper (A) such as “New NPI fine quality” manufactured by Co., Ltd., High quality coated paper such as “Silver Diamond” manufactured by Nippon Paper Industries, Ltd., “OK Everlight Coat” manufactured by Oji Paper Co., Ltd. and Japan Light coated paper (A3), such as fine coated paper such as “Aurora S” manufactured by Paper Manufacturing Co., Ltd., “OK Coat L” manufactured by Oji Paper Co., Ltd. and “Aurora L” manufactured by Nippon Paper Industries Co., Ltd. Coated paper (A2, B2) such as “OK Top Coat +” manufactured by Oji Paper Co., Ltd. and “Aurora Coat” manufactured by Nippon Paper Industries Co., Ltd. “OK Kanto +” manufactured by Oji Paper Co., Ltd. and Mitsubishi Paper Industries Art paper (A1) such as “Tokuhishi Art” manufactured by Co., Ltd., and the like. It is also possible to use various photographic papers for ink jet recording.

Among the above, from the viewpoint of obtaining a high-quality image having a large color density and hue better than the conventional one, the water absorption coefficient Ka is preferably 0.05 mL / m ² ···. ms ^1/2 is a recording medium ~0.5mL / m ² · ms ^1/2, more preferably recording of ^{0.1mL / m 2 · ms 1/2 ~0.4mL} / m 2 · ms 1/2 a medium, more preferably a recording medium ^{0.2mL / m 2 · ms 1/2 ~0.3mL} / m 2 · ms 1/2.
The water absorption coefficient Ka is synonymous with that described in JAPAN TAPPI paper pulp test method No. 51: 2000 (issued by Japan Paper Pulp Technology Association). Specifically, the absorption coefficient Ka is an automatic scanning absorption meter. It is calculated from the difference in the amount of water transferred between the contact time of 100 ms and the contact time of 900 ms using KM500Win (manufactured by Kumagai Riki Co., Ltd.).

  Among the recording media, so-called coated paper used for general offset printing is preferable. The coated paper is obtained by applying a coating material to the surface of high-quality paper, neutral paper, or the like that is mainly surface-treated with cellulose as a main component and is not surface-treated. The coated paper tends to cause quality problems such as image gloss and scratch resistance in image formation by ordinary aqueous inkjet, but in the inkjet recording method of the present invention, gloss unevenness is suppressed and gloss and resistance are reduced. An image having good rubbing properties can be obtained. In particular, it is preferable to use a coated paper having a base paper and a coat layer containing kaolin and / or calcium bicarbonate. More specifically, art paper, coated paper, lightweight coated paper, or finely coated paper is more preferable.

<Heat drying process>
In the image forming method of the present invention or the ink jet recording method of the present invention, water and a water-soluble organic solvent used together as necessary are evaporated from the ink composition applied or discharged onto the recording medium by a heating means. Including a heat drying step.
The heat drying step is performed between the applying step and the irradiation step in the image forming method of the present invention, and between the discharge step and the irradiation step in the ink jet recording method of the present invention.
A process of applying heat to the applied or ejected ink composition of the present invention to fix it will be described.
The heating means is not limited as long as it can dry water and a water-soluble organic solvent used in combination as required, but a heat drum, hot air, an infrared lamp, a heat oven, a heat plate heating or the like is used. Can do.
The heating temperature is not particularly limited as long as water present in the ink composition and the water-soluble organic solvent used in combination as needed can be evaporated to form a film, but if it is 40 ° C. or higher, the heating temperature is not limited. Since an effect is acquired, it is preferable, 40 to 150 degreeC is more preferable, and 40 to 80 degreeC is still more preferable.
The drying / heating time is not particularly limited as long as water present in the ink composition and the water-soluble organic solvent used in combination as needed can be evaporated and a film of the resin agent can be formed. It can be appropriately set in consideration of the composition and printing speed of the composition.

<Irradiation process>
Hereinafter, the irradiation step in the image forming method of the present invention and the irradiation step in the inkjet recording method of the present invention will be described.
The irradiation step in the image forming method of the present invention is not particularly limited as long as it is a step of irradiating the ink composition applied on the recording medium with active energy rays.
The ink jet recording method of the present invention preferably includes an irradiation step of irradiating the ejected ink composition with an active energy ray to cure the ink composition.
Examples of active energy rays that can be used in the irradiation step include ultraviolet rays (hereinafter also referred to as UV light), visible light glands, electron beams, and the like, and UV light is preferably used.
The peak wavelength of UV light depends on the absorption characteristics of the sensitizing dye used as necessary, but is preferably 200 to 405 nm, more preferably 250 to 405 nm, and 250 to 390 nm, for example. More preferably.
The output of the UV light is preferably at 2,000 mJ / cm ² or less, more preferably ^{10mJ / cm 2 ~2,000mJ / cm 2} , is 20mJ / cm ² ~1,000mJ / cm ² it is more preferable, and particularly preferably ^{50mJ / cm 2 ~800mJ / cm 2} .
Furthermore, UV light, the illumination intensity on the exposed surface, preferably ^{10mW / cm 2 ~2,000mW / cm 2} , more preferably it is suitable to be irradiated with ^{20mW / cm 2 ~1,000mW / cm 2} .
As the UV light source, mercury lamps, gas / solid lasers, and the like are mainly used, and mercury lamps and metal halide lamps are widely known. In addition, replacement with GaN-based semiconductor ultraviolet light-emitting devices is very useful from an industrial and environmental viewpoint. Yes, it is expected as a UV light source.
The ink composition of the present invention is suitably irradiated with such UV light, preferably for 0.01 seconds to 120 seconds, more preferably for 0.1 seconds to 90 seconds.
Irradiation conditions and basic irradiation methods are disclosed in JP-A-60-132767. Specifically, a light source is provided on both sides of the head unit including the ink ejection device, and the head unit and the light source are scanned by a so-called shuttle method, or another light source that is not driven and driven is used. Is preferred. Irradiation with active energy rays takes a certain time (preferably 0.01 seconds to 60 seconds, more preferably 0.01 seconds to 30 seconds, still more preferably 0.01 seconds to 15 seconds) after ink landing and thermal fixing. Will be done.

<Ink set>
The ink set of the present invention may include at least one kind of the ink composition of the present invention and at least one kind of treatment liquid containing an aggregating agent capable of forming an aggregate upon contact with the ink composition. .
By forming an image using the ink composition and a treatment liquid containing an aggregating agent, an image having good image quality, high curing sensitivity, and excellent blocking resistance is formed.
Moreover, it is preferable that the image forming method of the present invention further includes a treatment liquid application step of applying an acidic treatment liquid on the recording medium before the application step.
The ink jet recording method of the present invention preferably further includes a treatment liquid application step of applying an acidic treatment liquid onto the recording medium before the ejection step.

[Treatment solution]
The ink set of the present invention includes at least one flocculant capable of forming an aggregate upon contact with the ink composition, and includes other components as necessary.
When the treatment liquid contains an aggregating agent, the curability is good, and an image excellent in blocking resistance can be formed with good image quality.

[Flocculant]
The treatment liquid in the present invention comprises an aggregating agent that aggregates the components in the ink composition.
The flocculant in the present invention is capable of aggregating (fixing) the ink composition by contacting with the ink composition on the recording medium, and functions as a fixing agent. For example, when the treatment liquid is applied to a recording medium (preferably coated paper) and the flocculant is present on the recording medium, the ink composition further drops and comes into contact with the flocculant. The components in the ink composition are aggregated, and the components in the ink composition can be fixed on the recording medium.
Examples of the component for fixing the components in the ink composition include acidic compounds, polyvalent metal salts, and cationic polymers. These can be used alone or in combination of two or more.

-Acidic compounds-
Examples of acidic compounds include sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, polyacrylic acid, acetic acid, glycolic acid, malonic acid, malic acid, maleic acid, ascorbic acid, succinic acid, glutaric acid, fumaric acid, citric acid, and tartaric acid. , Lactic acid, sulfonic acid, orthophosphoric acid, metaphosphoric acid, pyrrolidone carboxylic acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, and derivatives of these compounds, In addition, preferable examples thereof include salts thereof.
Among these, acidic compounds with high water solubility are preferable. Further, from the viewpoint of fixing the whole ink by reacting with the ink composition, an acidic compound having a valence of 3 or less is preferable, and an acidic compound having a valence of 2 or more is particularly preferable.
An acidic compound may be used individually by 1 type, and may use 2 or more types together.
When the treatment liquid contains an acidic compound, the pH (25 ° C.) of the treatment liquid is preferably 0.1 to 6.8, more preferably 0.5 to 6.0, 0.8 More preferably, it is -5.0.

The content of the acidic compound is preferably 40% by weight or less, more preferably 15 to 40% by weight, and still more preferably 15 to 35% by weight with respect to the total weight of the treatment liquid. It is particularly preferably 20 to 30% by weight. By setting the content of the acidic compound to 15 to 40% by weight, the components in the ink composition can be more efficiently fixed.
The amount of the acidic compound applied to the recording medium is not particularly limited as long as it is an amount sufficient to aggregate the ink composition, but 0.5 g / m ² to 4 from the viewpoint that the ink composition can be easily fixed. is preferably .0g / m ^2, more preferably ^{0.9g / m 2 ~3.75g / m 2} .

-Multivalent metal salt-
The polyvalent metal salt in the present invention is a compound containing a divalent or higher metal such as an alkaline earth metal and a zinc group metal, and acetates, oxidations of metal ions such as Ca ²⁺ , Cu ²⁺ and Al ^3+. And the like.
In the present invention, the aggregation reaction of the ink composition when the ink composition is ejected onto a recording medium (preferably coated paper) to which the treatment liquid containing the polyvalent metal salt is applied is dispersed in the ink composition. This can be achieved by reducing the dispersion stability of the particles, for example, colorants typified by pigments and resin particles, and increasing the viscosity of the entire ink composition. For example, when particles such as pigments and resin particles in the ink composition have weakly acidic functional groups such as carboxyl groups, the particles are dispersed and stabilized by the action of the weakly acidic functional groups. Can be reduced by interacting with the polyvalent metal salt to lower the dispersion stability. Therefore, the polyvalent metal salt as the immobilizing agent contained in the treatment liquid needs to have a valence of 2 or more, that is, multivalent from the viewpoint of the aggregation reaction. A polyvalent metal salt composed of a polyvalent metal ion having a valence higher than that is preferable.
From the above viewpoint, the polyvalent metal salt that can be used in the treatment liquid in the present invention is any one or more of the following salts of polyvalent metal ions and anions, polyaluminum hydroxide, and polyaluminum chloride. Preferably there is.
Examples of the polyvalent metal ion include Ca ²⁺ , Cu ²⁺ , Ni ²⁺ , Mg ²⁺ , Sr ²⁺ , Zn ²⁺ , Ba ²⁺ , Al ³⁺ , Fe ³⁺ , Cr ³⁺ , Co ³⁺ , Fe ²⁺ , La ³⁺ , Nd ³⁺ , Y ³⁺ , Zr ^{4+ and the} like can be mentioned. In order to contain these polyvalent metal ions in the treatment liquid, the polyvalent metal salt may be used.

The salt is a metal salt composed of the above polyvalent metal ions and an anion that binds to these ions, but is preferably soluble in a solvent. Here, the said solvent is a medium which comprises a process liquid with a polyvalent metal salt, for example, water and an organic solvent are mentioned.
Preferred anions for forming a salt with the polyvalent metal ion include, for example, Cl ⁻ , NO ₃ ⁻ , I ⁻ , Br ⁻ , ClO ₃ ⁻ , CH ₃ COO ⁻ , SO ₄ ^{2− and the} like. .
A polyvalent metal ion and an anion can form a salt of a polyvalent metal ion and an anion, respectively, using a single species or a plurality of species.
Examples of other polyvalent metal salts include polyaluminum hydroxide and polyaluminum chloride.
In the present invention, it is preferable to use a salt of a polyvalent metal ion and an anion from the viewpoints of reactivity, colorability, and ease of handling, and examples of the polyvalent metal ion include Ca ²⁺ , Mg ^At least one selected from the group consisting of ²⁺ , Sr ²⁺ , Al ³⁺ and Y ³⁺ is preferred, and Ca ²⁺ is more preferred.
As the anion, NO ₃ ⁻ is particularly preferable from the viewpoint of solubility and the like.

The said polyvalent metal salt can be used individually by 1 type or in mixture of 2 or more types.
Content of the said polyvalent metal salt is 15 weight% or more with respect to the total weight of the said process liquid. By setting the content of the polyvalent metal salt to 15% by weight or more, the components in the ink composition can be more effectively fixed.
The content of the polyvalent metal salt is preferably 15% by weight to 35% by weight and more preferably 20% by weight to 30% by weight with respect to the total weight of the treatment liquid.
The amount of the polyvalent metal salt applied to the recording medium is not particularly limited as long as it is an amount sufficient to aggregate the ink composition, but 0.5 g / m ² from the viewpoint that the ink composition can be easily fixed. it is preferably to 4.0 g / m ^2, more preferably ^{0.9g / m 2 ~3.75g / m 2} .

-Cationic polymer-
The cationic polymer is at least one selected from the group consisting of poly (vinyl pyridine) salt, polyalkylaminoethyl acrylate, polyalkylaminoethyl methacrylate, poly (vinyl imidazole), polyethyleneimine, polybiguanide, and polyguanide. The cationic polymer.
A cationic polymer may be used individually by 1 type, and may use 2 or more types together.
Among the cationic polymers, polyguanides (preferably poly (hexamethyleneguanidine) acetate, polymonoguanide, polymeric biguanide), polyethyleneimine, and poly (vinylpyridine), which are advantageous from the viewpoint of aggregation rate, are preferable.
The weight average molecular weight of the cationic polymer is preferably smaller in terms of the viscosity of the treatment liquid. When the treatment liquid is applied to the recording medium by an inkjet method, a range of 500 to 500,000 is preferable, a range of 700 to 200,000 is more preferable, and a range of 1,000 to 100,000 is more preferable. When the weight average molecular weight is 500 or more, it is advantageous from the viewpoint of aggregation speed, and when it is 500,000 or less, it is advantageous from the viewpoint of ejection reliability. However, this is not the case when the treatment liquid is applied to the recording medium by a method other than inkjet.
When the treatment liquid contains a cationic polymer, the pH (25 ° C.) of the treatment liquid is preferably 1.0 to 10.0, more preferably 2.0 to 9.0, and 3. More preferably, it is 0-7.0.
The content of the cationic polymer is preferably 1% by weight to 35% by weight and more preferably 5% by weight to 25% by weight with respect to the total weight of the treatment liquid.
The amount of the cationic polymer applied to the coated paper is not particularly limited as long as it is an amount sufficient to stabilize the ink composition. it is preferably ^{2 ~4.0g} / m ^2, more preferably ^{0.9g / m 2 ~3.75g / m 2} .

[Processing liquid application process]
The image forming method of the present invention preferably further includes a treatment liquid application step of applying an acidic treatment liquid onto the recording medium before the application step.
Moreover, it is preferable that the inkjet recording method of this invention further includes the process liquid provision process of apply | coating an acidic process liquid on a recording medium before the said discharge process.
In the treatment liquid application step, a treatment liquid containing a flocculant contained in the ink set is applied on the recording medium. For applying the treatment liquid to the recording medium, a known liquid application method can be used without particular limitation, and any method such as spray application, application by an application roller, application by an inkjet method, immersion, etc. can be selected. .
Specifically, for example, a size press method represented by a horizontal size press method, a roll coater method, a calendar size press method, etc .; a knife coater method represented by an air knife coater method; a transfer roll such as a gate roll coater method Roll coater method represented by coater method, direct roll coater method, reverse roll coater method, squeeze roll coater method, etc .; bill blade coater method, short duel coater method; blade coater method represented by two stream coater method; rod Examples include a bar coater method typified by a bar coater method, a cast coater method, a gravure coater method, a curtain coater method, a die coater method, a brush coater method, and a transfer method.
Moreover, the method of apply | coating by controlling a coating amount by using the coating device provided with the liquid quantity limiting member like the coating device of Unexamined-Japanese-Patent No. 10-230201 may be used.

The area to which the treatment liquid is applied may be the entire area application to the entire recording medium, or the partial application to be partially applied to the area where image formation such as ink jet recording is performed in the ink application process. In the present invention, the application amount of the treatment liquid is uniformly adjusted, and fine lines and fine image portions are uniformly recorded, and from the viewpoint of suppressing density unevenness such as image unevenness, coating is performed by application using an application roller or the like. It is preferable to apply the entire surface to the entire paper.
Examples of the method of applying the treatment liquid while controlling the application amount of the treatment liquid within the above range include a method using an anilox roller. An anilox roller is a roller with a ceramic-sprayed roller surface processed with a laser to give it a pyramid shape, a diagonal line, a turtle shell shape, or the like. The treatment liquid enters the dent portion formed on the roller surface, is transferred when it comes into contact with the paper surface, and is applied in an application amount controlled by the dent of the anilox roller.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to these examples.
In the following description, “parts” means “parts by weight” unless otherwise specified.
The pigment dispersions and ink composition materials used in the examples and comparative examples are shown below.

<Synthesis of Polymer Dispersant D-1>
To a three-necked flask equipped with a stirrer and a condenser, 44 g of methyl ethyl ketone was added and heated to 70 ° C. under a nitrogen atmosphere. Here, 25 parts of methyl ethyl ketone was added with 0.43 part of dimethyl 2,2′-azobisisobutyrate and benzyl methacrylate. A solution in which 30 parts, 5 parts of methacrylic acid and 15 parts of methyl methacrylate were dissolved was dropped over 3 hours. After completion of the dropwise addition, the reaction was further continued for 1 hour, and then a solution in which 0.21 part of dimethyl 2,2′-azobisisobutyrate was dissolved in 1 part of methyl ethyl ketone was added, heated to 78 ° C. and heated for 4 hours. The obtained reaction solution was reprecipitated twice in a large excess amount of hexane, and the deposited resin was dried to obtain 43 parts of a polymer dispersant D-1.
The composition of the obtained resin was confirmed by ¹ H-NMR, and the weight average molecular weight (M _w ) determined by GPC was 45,000. Furthermore, when the acid value was calculated | required by the method as described in a JIS specification (JISK0070: 1992), it was 65.5 mgKOH / g.

<Preparation of dispersion of resin-coated pigment>
(Resin-coated cyan pigment dispersion (C))
Pigment Blue 15: 3 (phthalocyanine blue A220, manufactured by Dainichi Seika Kogyo Co., Ltd.), 5 parts of the polymer dispersant D-1, 42 parts of methyl ethyl ketone, and 5.5 parts of 1 mol / L NaOH aqueous solution. And 87.2 parts of ion-exchanged water were mixed and dispersed by a bead mill for 2 to 6 hours using 0.1 mmφ zirconia beads.
Methyl ethyl ketone was removed from the obtained dispersion under reduced pressure at 55 ° C., and a part of water was further removed to obtain a resin-coated cyan pigment dispersion (C) having a pigment concentration of 10.2% by weight.

(Resin-coated magenta pigment dispersion (M))
In the preparation of the resin-coated cyan pigment dispersion, the resin coating was carried out in the same manner as above except that Chromathal Jet Magenta DMQ (Pigment Red 122, manufactured by BASF Japan) was used instead of phthalocyanine blue A220 used as the pigment. A magenta pigment dispersion (M) was obtained.

(Resin-coated yellow pigment dispersion (Y))
Resin-coated yellow was prepared in the same manner as described above except that Irgalite Yellow GS (Pigment Yellow 74, manufactured by BASF Japan Ltd.) was used instead of phthalocyanine blue A220 used as a pigment in the preparation of the resin-coated cyan pigment dispersion. A pigment dispersion (Y) was obtained.

(Resin-coated black pigment dispersion (K))
In the preparation of the resin-coated cyan pigment dispersion, a resin was obtained in the same manner as above except that the pigment dispersion CAB-O-JETTM 200 (carbon black, manufactured by CABOT) was used instead of the phthalocyanine blue A220 used as the pigment. A coated black pigment dispersion (K) was obtained.

<Printing on polyvinyl chloride sheet>
(Preparation of ink composition)
Using the obtained dispersions (C dispersion, M dispersion, Y dispersion, K dispersion), ink compositions of Examples 1 to 6 having the compositions shown in Table 1 below and Comparative Examples 1 and 2 Were stirred at 2,500 rpm for 10 minutes using a mixer (Silverson L4R) to prepare each. The obtained ink composition was packed in a plastic disposable syringe, and filtered through a polyvinylidene fluoride (PVDF) pore size 5 μm filter (Millex-SV, Millipore, diameter 25 mm) to obtain a finished ink composition. .
Further, the viscosity of the ink composition was measured using a VISCOMETER TV-22 (manufactured by TOKI SANGYOCO. LTD) under the condition of 25 ° C. It was.
The obtained ink was used as a K hand coater manufactured by RK PRINT COAT INSTRUMENTS No. Using 2 bars, a polyvinyl chloride sheet (AVERY 400 GLOSS WHITE PERMANENT, manufactured by Avery Dennison Co., Ltd.) was applied to a thickness of 12 μm. Further, the moisture was dried at 60 ° C. for 3 minutes.
Using the obtained coating film, the following fixability was evaluated. The evaluation results are shown in Table 1.

<Curability evaluation>
The obtained coating film was exposed with a Deep UV lamp (US-7, SP-7) under the condition of an energy of 1,500 mJ / cm ² . The degree of fixation on the film surface was evaluated by palpation. When the stickiness remained, the exposure was repeated until the stickiness disappeared, and the curability was evaluated by the exposure amount until the stickiness disappeared.
A: No stickiness after 2 exposures B: No stickiness after 2 to 3 exposures C: No stickiness after 4-5 exposures D: No stickiness after 6 or more exposures

<Solvent resistance evaluation>
Each of the obtained ink compositions and the printed material prepared by evaluation of curability were used, and solvent resistance was evaluated as an index for judging curability by a method different from the above.
The coating film obtained by the above-described evaluation of curability was further exposed with a Deep UV lamp (US-7, SP-7) under the condition of energy of 6,000 mJ / cm ² . The surface of the printed material exposed under an energy condition of 6,000 mJ / cm ² was rubbed with a cotton swab impregnated with isopropyl alcohol and evaluated according to the following criteria. The evaluation results are shown in Table 1.
A: No change was observed in the image even after rubbing 9 times or more.
B: Image density decreased after 5 to 9 rubbing.
C: Image density decreased after 2-4 rubbing.
D: Image density was significantly reduced by just rubbing once.

<Ejection recovery evaluation>
As an inkjet recording apparatus, a commercially available inkjet printer (SP-300V manufactured by Roland DG) was prepared. Each obtained ink composition was loaded into the above-mentioned ink jet printer, and ejected from a head for 10 minutes in a standard printing mode onto a vinyl chloride sheet (Avery 400 GLOSS WHITE PERMANENT, manufactured by Avery Dennison) to record a solid image and fine lines. did. After stopping the discharge for 10 minutes, it was discharged again for 10 minutes in the standard printing mode, and a solid image and an image (5 cm × 5 cm) obtained by recording fine lines were observed. The observed images were visually evaluated according to the following evaluation criteria.
A: The occurrence of missing dots due to the occurrence of missing or the like was not recognized, and a good image was obtained.
B: Although the occurrence of missing dots due to the occurrence of omission was slightly observed, it was of a level that would not cause any practical problems.
C: The image lacked practical use due to the occurrence of missing dots due to the occurrence of omission.
D: Unable to discharge.

<Printing on printing paper>
(Preparation of ink composition)
Using the obtained dispersions (C dispersion, M dispersion, Y dispersion, K dispersion), ink compositions of Examples 7 to 10 and Comparative Examples 3 and 4 having the compositions shown in Table 2 below. Was prepared by stirring, mixing, and filtering in the same manner as in Examples 1-6.

<Preparation of treatment solution>
Treatment liquid 1 was prepared by mixing the following materials. It was 1.0 when the pH (25 degreeC) of the processing liquid 1 was measured with pH meter WM-50EG by Toa DKK Corporation.
-Treatment solution composition-
Malonic acid: 25.0% by weight
Tripropylene glycol monomethyl ether: 5.0% by weight
(Water-soluble organic solvent)
-Ion exchange water: 70.0% by weight

<Inkjet recording>
As a recording medium, Tokuhishi Art (basis weight 105 g / m ² , manufactured by Mitsubishi Paper Industries Co., Ltd.) was prepared, an image was formed as follows, and the following evaluation was performed on the formed image.
As the ink composition, the ink composition obtained above was used, and a line image and a solid image were formed by single pass recording together with the treatment liquid.
At this time, a line image was formed by ejecting 1,200 dpi 1-dot wide lines, 2-dot wide lines, and 4-dot wide lines in the main scanning direction by a single pass.
The solid image was formed by discharging the ink composition over the entire surface of the sample obtained by cutting the recording medium into A5 size. The conditions for recording are as follows.

(1) Treatment liquid application process The entire surface of the recording medium is processed with a roll coater whose application amount is controlled by an anilox roller (number of lines: 100 to 300 / inch) so that the application amount is 1.4 g / m ^2. The liquid was applied.

(2) Processing Step Next, a drying treatment and a permeation treatment were performed on the recording medium coated with the treatment liquid under the following conditions.
・ Wind speed: 10m / s
-Temperature: Heated by a contact type flat heater from the opposite side of the recording surface of the recording medium so that the surface temperature of the recording surface of the recording medium was 55 ° C.

(3) Ink application step Thereafter, the ink composition was ejected by an inkjet method on the application surface of the recording medium coated with the treatment liquid under the following conditions to form a line image and a solid image, respectively.
・ Head: 1,200 dpi / 20 inch wide piezo full line head for 4 colors ・ Discharged droplet volume: 2.0 pL
・ Drive frequency: 30kHz

(4) Ink drying step Next, the recording medium provided with the ink composition was dried under the following conditions.
・ Drying method: blow drying ・ wind speed: 15m / s
-Temperature: Heated by a contact type flat heater from the opposite side (back side) of the recording surface of the recording medium so that the surface temperature of the recording surface of the recording medium was 60 ° C.

(5) Active energy ray irradiation step Next, using a metal halide lamp (output: 120 W / cm ² ), the recording image is irradiated with ultraviolet rays as active energy rays under the condition of 1,200 mJ / cm ² energy. Thus, an image-formed evaluation sample was obtained.

<Evaluation>
The evaluation sample obtained above was subjected to an ink drawing quality test, a curability test, an image blocking resistance test, and a tape adhesion test as follows. The results are shown in Table 2.

<Curability evaluation>
Unprinted of Tokubishi Both Side Art N (manufactured by Mitsubishi Paper Mills Co., Ltd.) paperweight winding (weight 470 g, size 15 mm × 30 mm × 120 mm) (the area evaluation sample is in contact with Tokubishi Art unprinted is 150 mm ²⁾ The stamp screen of the evaluation sample on which the solid image was formed was rubbed twice (corresponding to a load of 260 kg / m ² ). The marking screen after rubbing was visually observed and evaluated according to the following evaluation criteria.
-Evaluation criteria-
A: Image peeling was not visible on the printed surface.
B: Slight peeling of the image was recognized on the printing surface.
C: Image peeling was visually recognized on the print surface, and it was a level causing a problem in practical use.

<Blocking resistance evaluation>
As an index for judging curability by a method different from the above, the blocking resistance was evaluated by the following method.
Immediately after printing, the evaluation sample on which the solid image was formed was cut into a 2 cm square, and on the printing screen, an unrecorded recording medium (the same recording medium used for recording (hereinafter, unused in this evaluation) sample called.)) under a load 350 kg / m ² to overlap the, 60 ° C., under ambient conditions of RH 30%, and left for 24 hours. The unused sample was peeled off from the evaluation sample, the degree of ink transfer to the white background of the unused sample was visually observed, and evaluated according to the following evaluation criteria.
-Evaluation criteria-
A: There was no transfer of ink.
B: Ink transfer was hardly noticeable.
C: Ink transfer was observed to some extent, and it was at a level causing a practical problem.
D: Ink transfer was remarkable.

<Tape adhesion evaluation>
As an index for judging curability by a method different from the above, the tape adhesion was evaluated by the following method.
An adhesive tape (trade name: Cellotape (registered trademark), manufactured by Nichiban Co., Ltd.) was applied to an evaluation sample so that the tape was attached to the entire surface, and then immediately peeled off. The color transfer to the peeled tape and the paper surface of the tape peeling part were observed, and the tape adhesion was evaluated according to the following evaluation criteria.
-Evaluation criteria-
A: Color transfer was slightly observed on the adhesive tape, but there was no image peeling from the paper surface.
B: Although color transfer was recognized in the adhesive tape, there was no image peeling from the paper surface.
C: Color transfer was observed on the adhesive tape, and image peeling partially occurred from the paper surface.
D: The color transferred to the entire surface of the adhesive tape, and image peeling from the paper surface occurred.

<Drawing quality (image uniformity) test>
In the ink jet recording, the solid image obtained was subjected to the heat fixing process described above.
The solid image after heat fixing was visually observed, and the uniformity of the image was evaluated according to the following criteria. The evaluation results are shown in Table 2 below.
-Evaluation criteria-
A: Uniformity with no color unevenness or white stripes was observed.
B: When looked closely, rare white spots were rarely observed, but were almost uniform as a whole.
C: Slightly fine white spots are observed, but the difference in shading is very slight.
D: Striped white spots were scattered and a partial shading difference was observed, but it was within a practically acceptable range.
E: Large striped shading occurred and exceeded the practically acceptable range.

  Details of the abbreviations used in Tables 1 and 2 are as follows.

2PD: 2-pyrrolidone (manufactured by Sigma-Aldrich Japan Co., Ltd.)
TEG: Triethylene glycol (manufactured by Sigma-Aldrich Japan)
P-Gxl: Proxel GXL (Abyssia)
G-100: Glide 100 (manufactured by Tego Chemical Service)
I-2959: Irgacure 2959 (manufactured by BASF Japan Ltd.)
HEAA: 2-hydroxyethylacrylamide (manufactured by Sigma Aldrich Japan Co., Ltd.)
EBAA: N, N′-ethylenebis (acrylamide) (manufactured by Sigma Aldrich Japan Co., Ltd.)
E-1010: Olfine E1010 (Nisshin Chemical Industry Co., Ltd.)

Claims (11)

(Component A) a (meth) acrylamide compound represented by the following formula (1),
(Component B) a polymerization initiator, and
An ink composition comprising (Component C) a colorant.

(In the formula (1), Ar represents an (m + n) -valent aromatic group, X represents an ionic group, R represents a group having a (meth) acrylamide group, and m and n are each independently 1 (It represents the integer above.)   The ink composition according to claim 1, wherein X is —COONa, —COOH, or —ONa.   The ink composition according to claim 1 or 2, wherein X is -COONa or -COOH.   The ink composition according to claim 1, further comprising (Component D) water.   The ink composition according to any one of claims 1 to 4, which is for inkjet recording.   The ink composition according to any one of claims 1 to 5, wherein the molecular weight of Component A is 180 to 800. The ink composition according to any one of claims 1 to 6, wherein Component A is a compound represented by the following formula (2).

(In the formula (2), the R ¹ to R ⁴ each independently represent a hydrogen atom or an alkyl group, Y ¹ and Y ² each independently represent a single bond or a divalent organic group, X is an ionic Represents a group, and n represents an integer of 1 to 4.)   (Component E) The ink composition according to any one of claims 1 to 7, further comprising a polymerizable compound other than Component A.   The ink composition according to claim 8, wherein Component E comprises a monofunctional polymerizable compound. A discharge step of discharging the ink composition according to claim 4 onto a recording medium;
A heating and drying step of evaporating at least water from the ink composition ejected by the heating means; and
An ink jet recording method comprising: an irradiation step of irradiating the discharged ink composition with active energy rays to cure the ink composition.   The inkjet recording method according to claim 10, further comprising a treatment liquid application step of applying an acidic treatment liquid on the recording medium before the ejection step.