WO2019049689A1 - Ink composition and image formation method - Google Patents

Abstract

Provided are an ink composition and an image formation method using said ink composition, said ink composition containing: a pigment indicated by formula (1); a polymer dispersant including a repeating unit having a hydrophilic group and a repeating unit having an aromatic group; polymer particles including a repeating unit having a hydrophilic group and a repeating unit having an cyclic aliphatic group; and water. Z indicates a 5-member heterocycle or 6-member heterocycle that may have a substituted group. Y1, Y2, R11, and R12 each independently indicate a hydrogen atom or a substituted group. G1 and G2 each independently indicate a hydrogen atom or a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclic group. W1 and W2 each independently indicate a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.

Description

Ink composition and image forming method

The present invention relates to an ink composition and an image forming method.

Azo pigments are widely used in various fields because they are excellent in color characteristics such as hue and coloring power. For example, an ink composition in which an azo pigment is dispersed in water is used for an inkjet ink or the like.
Patent documents 1 and 2 describe an ink composition containing an azo pigment of a specific structure and a vinyl polymer having an aromatic group. Patent Documents 1 and 2 also describe that the ink composition may further contain polymer particles having an aromatic group.
Patent Document 3 describes an ink composition containing an azo pigment having a specific structure and a vinyl polymer having a cyclic aliphatic group. Patent Document 3 also describes that the ink composition may further contain polymer particles having an aromatic group.
Patent Document 4 describes an ink composition containing a colorant, a resin dispersant having an aromatic group, and a polymer particle having a cyclic aliphatic group.

Japan JP 2011-74377 Japan JP 2012-25866 gazette Japan JP 2011-57732 Japan JP 2011-46908

Although the ink compositions described in Patent Documents 1 to 4 each show useful performance, in recent years, the light resistance of the printed matter obtained using the ink composition is still higher than conventional levels. It is desirable to satisfy light resistance.
The problem to be solved by the present invention is to provide an ink composition and an image forming method that can provide a print having excellent light resistance.

As a result of intensive studies by the present inventors, it was found that the specific azo pigment, the polymer dispersant containing the repeating unit having a hydrophilic group and the repeating unit having an aromatic group, and the repeating unit having a hydrophilic group and the cyclic fat. It has been found that an ink composition containing a polymer particle containing a repeating unit having a group group can provide a print having very excellent light resistance.

Although the factors by which the ink composition of the present invention can provide a print having excellent light resistance is not clear in detail, the present inventors estimate as follows.
With the aim of improving light resistance by forming a resin film on the surface of a print, the inventors of the present invention have studied pigments and polymer particles while adding film-forming polymer particles to the ink composition. We focused on the adsorption effect of The pigment represented by the general formula (1) in the present invention is characterized in that the adsorptivity to aromatic groups is high and the adsorptivity to non-aromatic groups is low. When the polymer particles have an aromatic group, the adhesion between the polymer particles and the pigment particles occurs partially when the ink composition is dried, so that the pigment is also present on the surface of the film, and the light resistance improvement effect as intended I thought it was hard to come out. Therefore, the main object is to suppress the fusion between the polymer particles and the pigment particles, and the pigment dispersant uses a polymer dispersant containing an aromatic group that adsorbs well to the pigment, and the polymer particles adsorb the pigment. It was decided to use a polymer containing a cyclic aliphatic group which is a difficult nonaromatic group. As a result, the improvement of light resistance was achieved as intended. Furthermore, it has also been found that there is an effect of improving the abrasion resistance or improving the gloss by stabilizing the pigment particles.

That is, the above-mentioned subject of the present invention is solved by the following means.

<1>
A pigment (P) represented by the following general formula (1), a polymer dispersant (D) containing a repeating unit having a hydrophilic group and a repeating unit having an aromatic group, a repeating unit having a hydrophilic group and a cyclic fat An ink composition comprising: polymer particles (B) comprising a repeating unit having a group group; and water.

In general formula (1),
Z represents a 5- or 6-membered heterocyclic ring which may have a substituent.
Y ₁ , Y ₂ , R ₁₁ and R ₁₂ each independently represent a hydrogen atom or a substituent.
G ₁ and G ₂ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted group It represents an aryl group or a substituted or unsubstituted heterocyclic group.
W ₁ and W ₂ each independently represent a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.
<2>
The ink composition as described in <1> whose cyclic aliphatic group contained in the said polymer particle (B) is a polycyclic aliphatic hydrocarbon group.
<3>
The repeating unit having a cyclic aliphatic group contained in the polymer particle (B) is a repeating unit represented by the following general formula (b-1), a repeating unit represented by the following general formula (b-2), and The ink composition according to <1> or <2>, which is at least one selected from the group consisting of repeating units represented by the following general formula (b-3).

R _1b to R _3b in the general formulas (b-1) to (b-3) each independently represent a hydrogen atom or a methyl group.
<4>
The ink composition according to any one of <1> to <3>, wherein the volume average particle size of the polymer particles (B) is 1.4 to 30 nm.
<5>
The ink composition according to any one of <1> to <4>, wherein the pigment (P) is represented by the following general formula (1-1).

In the general formula (1-1),
R _1a , Y ₁ , Y ₂ , R ₁₁ and R ₁₂ each independently represent a hydrogen atom or a substituent.
G ₁ and G ₂ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted group It represents an aryl group or a substituted or unsubstituted heterocyclic group.
W ₁ and W ₂ each independently represent a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.
<6>
The ratio W _B / W _P which is the ratio of the content W _P of the pigment (P) in the ink composition to the content W _B of the polymer particles (B) is 1 or more <1> to <5 The ink composition according to any one of the above.
However, W _P is the ratio of the mass of the pigment (P) to the total mass of the ink composition (wt%), W _B is the ratio of the mass of the polymer particles to the total weight (B) of the ink composition (Mass%).
<7>
The ink composition according to any one of <1> to <6>, which is for inkjet.
<8>
An image forming method comprising the step of applying the ink composition according to any one of <1> to <6> onto a recording medium by an inkjet method.

According to the present invention, it is possible to provide an ink composition and an image forming method which can provide a print having excellent light resistance.

In the present specification, a numerical range represented using “to” means a range including numerical values described before and after “to” as the lower limit value and the upper limit value.
In the present specification, “(meth) acrylate” represents at least one of acrylate and methacrylate, “(meth) acrylic” represents at least one of acrylic and methacrylic, and “(meth) acryloyl” represents at least one of acryloyl and methacryloyl. Represents a kind.

The ink composition of the present invention comprises a pigment (P) represented by the following general formula (1), a polymer dispersant (D) containing a repeating unit having a hydrophilic group and a repeating unit having an aromatic group, hydrophilic It is a polymer particle (B) containing the repeating unit which has a group, and the repeating unit which has a cycloaliphatic group, and an ink composition containing water.

In general formula (1),
Z represents a 5- or 6-membered heterocyclic ring which may have a substituent.
Y ₁ , Y ₂ , R ₁₁ and R ₁₂ each independently represent a hydrogen atom or a substituent.
G ₁ and G ₂ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted group It represents an aryl group or a substituted or unsubstituted heterocyclic group.
W ₁ and W ₂ each independently represent a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.

The components used in the present invention will be described below.

(Pigment (P))
The ink composition of the present invention contains the pigment (P) represented by the above general formula (1).
The pigment (P) is a pigment containing the compound represented by the above general formula (1) or a tautomer thereof, or a salt thereof.

The pigment (P) is easy to form intramolecular and intermolecular interaction (hydrogen bond and π-π stacking) due to its specific structure, excellent in light resistance, low in solubility in water or organic solvent, etc., and preferred form Can be used as an azo pigment. The pigment is used by being dispersed in the medium as particles such as molecular assemblies. The ink composition of the present invention contains water as a medium, but in water, it is preferable that the pigment (P) is covered and dispersed by the polymer dispersant (D).

In the general formula (1), W ₁ and W ₂ each independently represent a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Represent.

When W ₁ and W ₂ represent a substituted or unsubstituted alkyl group, examples of the alkyl group include linear, branched and cyclic substituted or unsubstituted alkyl groups, and a cycloalkyl group, a bicycloalkyl group and a tricyclo structure Etc. are also included. The alkyl group (for example, the alkoxy group and the alkyl group of the alkylthio group) in the substituent demonstrated below represents the alkyl group of such a concept. The linear or branched substituted or unsubstituted alkyl group is preferably a substituted or unsubstituted alkyl group having 1 to 30 carbon atoms, and examples thereof include a methyl group, an ethyl group, an n-propyl group and an i- group. A propyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, n-octyl group, eicosyl group, 2-chloroethyl group, 2-cyanoethyl group, 2-ethylhexyl group and the like can be mentioned. The substituted or unsubstituted cycloalkyl group is preferably a substituted or unsubstituted cycloalkyl group having a carbon number of 3 to 30, and examples thereof include a cyclohexyl group, a cyclopentyl group and a 4-n-dodecylcyclohexyl group. . The substituted or unsubstituted bicycloalkyl group is preferably a substituted or unsubstituted bicycloalkyl group having 5 to 30 carbon atoms, that is, a hydrogen atom selected from a substituted or unsubstituted bicycloalkane having 5 to 30 carbon atoms Examples thereof include monovalent groups which have been removed, such as bicyclo [1,2,2] heptan-2-yl group, bicyclo [2,2,2] octan-3-yl group and the like. The substituents which the alkyl group may have will be described in more detail later.

The alkoxy group in the case where W ₁ and W ₂ represent a substituted or unsubstituted alkoxy group is preferably an alkoxy group having 1 to 30 carbon atoms, more preferably an alkoxy group having 1 to 8 carbon atoms, and 1 carbon atom. To 4 are more preferable. As the alkoxy group, for example, methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group, i-butoxy group, s-butoxy group, t-butoxy group, t-butoxy group, n-octyloxy group, 2 And -methoxyethoxy group etc. are mentioned, and particularly preferred is a methoxy group. The alkoxy group may have a substituent. The substituents will be described later.

When W ₁ and W ₂ each represent a substituted or unsubstituted amino group, the substituted or unsubstituted amino group is preferably an amino group, an alkylamino group, an arylamino group or a heterocyclic amino group, more preferably an amino group Group, an alkylamino group having 1 to 30 carbon atoms and anilino group having 6 to 30 carbon atoms, more preferably an amino group, an alkylamino group having 1 to 8 carbon atoms and an anilino group having 6 to 18 carbon atoms Particularly preferred are an amino group, an alkylamino group having 1 to 4 carbon atoms, and an anilino group having 6 to 12 carbon atoms. As a substituted or unsubstituted amino group, for example, amino group (-NH ₂ ), methylamino group (-NHCH ₃ ), dimethylamino group {-N (CH ₃ ) ₂ }, anilino group (-NH Ph), N And -methyl-anilino group {-N (CH ₃ ) Ph}, diphenylamino group {-N (Ph) ₂ } and the like can be mentioned, and an amino group is particularly preferable. Ph represents a phenyl group. The substituents which the amino group may have will be described in more detail later.

The aryl group in the case where W ₁ and W ₂ represent a substituted or unsubstituted aryl group is preferably an aryl group having 6 to 30 carbon atoms, and more preferably an aryl group having 6 to 18 carbon atoms, More preferred are 6 to 12 aryl groups. Examples of the substituted or unsubstituted aryl group include phenyl group, p-tolyl group, naphthyl group, m-chlorophenyl group, o-hexadecanoylaminophenyl group and the like. The substituent which the aryl group may have will be described in more detail later.

W ₁ and W ₂ each preferably independently represent a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group or a substituted or unsubstituted alkyl group, and a substituted or unsubstituted alkoxy group or a substituted or unsubstituted group More preferably, it represents a substituted amino group, more preferably an alkoxy group having 5 or less carbon atoms in total, an amino group (—NH ₂ group), or an alkylamino group having 5 or less carbon atoms in total. It is particularly preferable to represent the following alkoxy group or an alkylamino group having 3 or less carbon atoms in total, and most preferably a methoxy group.

In formula (1), R ₁₁ and R ₁₂ each independently represent a hydrogen atom or a substituent.
When R ₁₁ and R ₁₂ represent a substituent, examples of the substituent include a substituted or unsubstituted alkyl group (eg, a substituted or unsubstituted linear or branched alkyl group having 1 to 12 carbon atoms (eg, methyl Ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, 2-ethylhexyl, 2-methylsulfonylethyl, 3-phenoxypropyl, trifluoromethyl), substituted or not A substituted or unsubstituted aralkyl group having 7 to 18 carbon atoms, a substituted or unsubstituted linear or branched alkenyl group having 2 to 12 carbon atoms, a substituted or unsubstituted linear or branched alkynyl group having 2 to 12 carbon atoms A substituted or unsubstituted cycloalkyl group having 3 to 12 carbon atoms (eg, cyclopentyl), and a substituted or unsubstituted cycloalkenyl having 3 to 12 carbon atoms Group, a halogen atom (eg, chlorine atom, bromine atom), a substituted or unsubstituted aryl group (eg, phenyl, 4-t-butylphenyl, 2,4-di-t-amylphenyl), substituted or unsubstituted Heterocyclic group (for example, imidazolyl, pyrazolyl, triazolyl, 2-furyl, 2-thienyl, 2-pyrimidinyl, 2-benzothiazolyl), cyano group, hydroxyl group, nitro group, carboxy group, substituted or unsubstituted amino group, substituted Or unsubstituted alkyloxy group (eg, methoxy, ethoxy, 2-methoxyethoxy, 2-methylsulfonylethoxy), substituted or unsubstituted aryloxy group (eg, phenoxy, 2-methylphenoxy, 4-t-butylphenoxy) , 3-nitrophenoxy, 3-t-butyloxycarbonyl group Noxy, 3-methoxycarbonylphenyloxy), a substituted or unsubstituted acylamino group (eg, acetamide, benzamide, 4- (3-t-butyl-4-hydroxyphenoxy) butanamide), a substituted or unsubstituted alkylamino group (for example, For example, methylamino, butylamino, diethylamino, methylbutylamino), substituted or unsubstituted arylamino group (eg, phenylamino, 2-chloroanilino), substituted or unsubstituted ureido group (eg, phenylureido, methylureido) N, N-dibutyl ureide), substituted or unsubstituted sulfamoylamino group (eg, N, N-dipropylsulfamoylamino), substituted or unsubstituted alkylthio group (eg, methylthio, octylthio, 2-phenoxyethyl) Thio), substituted or unsubstituted arylthio group (eg, phenylthio, 2-butoxy-5-t-octylphenylthio, 2-carboxyphenylthio), substituted or unsubstituted alkyloxycarbonylamino group (eg, methoxycarbonylamino) ), A substituted or unsubstituted alkylsulfonylamino group and an arylsulfonylamino group (eg, methylsulfonylamino, phenylsulfonylamino, p-toluenesulfonylamino), a substituted or unsubstituted carbamoyl group (eg, N-ethylcarbamoyl, N , N-dibutylcarbamoyl), substituted or unsubstituted sulfamoyl group (eg, N-ethylsulfamoyl, N, N-dipropylsulfamoyl, N-phenylsulfamoyl), substituted sulfonyl group (eg, methyl) Sulfonyl, octylsulfonyl, phenylsulfonyl, p-toluenesulfonyl), substituted or unsubstituted alkyloxycarbonyl group (eg, methoxycarbonyl, butyloxycarbonyl), substituted or unsubstituted heterocyclic oxy group (eg, 1-phenyltetrazole) -5-oxy, 2-tetrahydropyranyloxy), substituted azo group (eg, phenylazo, 4-methoxyphenylazo, 4-pivaloylaminophenylazo, 2-hydroxy-4-propanoylphenylazo), substituted or substituted Unsubstituted acyloxy group (eg, acetoxy), substituted or unsubstituted carbamoyloxy group (eg, N-methylcarbamoyloxy, N-phenylcarbamoyloxy), substituted or unsubstituted silyloxy group (eg, trimethyl) Ryloxy, dibutylmethylsilyloxy), substituted or unsubstituted aryloxycarbonylamino group (eg, phenoxycarbonylamino), substituted imido group (eg, N-succinimide, N-phthalimido), substituted or unsubstituted heterocyclic thio group (Eg, 2-benzothiazolylthio, 2,4-di-phenoxy-1,3,5-triazole-6-thio, 2-pyridylthio), substituted or unsubstituted sulfinyl group (eg, 3-phenoxypropylsulfinyl) ), Substituted or unsubstituted phosphonyl group (eg, phenoxyphosphonyl, octyloxyphosphonyl, phenylphosphonyl), substituted or unsubstituted aryloxycarbonyl group (eg, phenoxycarbonyl), substituted or unsubstituted acyl group (eg, phenoxycarbonyl) For example, acetyl 3-phenylpropanoyl, benzoyl), ionic hydrophilic groups (eg, carboxyl group, sulfo group, phosphono group and quaternary ammonium group).

R ₁₁ and R ₁₂ each independently represent a substituted or unsubstituted acylamino group having 1 to 8 carbon atoms in total, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms in total, or 6 to 6 carbon atoms in total It is preferable to represent an aryl group of 18 or a substituted or unsubstituted heterocyclic group having 4 to 12 carbon atoms in total, a linear or branched alkyl group having 1 to 8 carbon atoms in total, or a substituted or unsubstituted alkyl group. It is more preferable to represent an aryl group having 6 to 18 carbon atoms, and a linear or branched alkyl group having 1 to 8 carbon atoms in total is preferable. Specifically, methyl, i-propyl or t-butyl is preferable, particularly i-propyl or t-butyl is preferable, and t-butyl is most preferable.

In the general formula (1), Z represents a 5- or 6-membered heterocyclic ring which may have a substituent, preferably a 3-membered 10-membered nitrogen-containing heterocyclic ring having 3 to 10 carbon atoms. Two substituents may combine with each other to form a fused ring. In addition, about a substituent, it mentions later.

The 5- or 6-membered heterocyclic ring represented by Z is a pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, pyrroline ring, furan ring, thiophene ring, pyrazole ring, imidazole ring, triazole ring, oxazole ring And thiazole ring, isothiazole ring, thiadiazole ring, isoxazole ring, pyrrolidine ring, piperidine ring, piperazine ring, imidazolidine ring, thiazoline ring and the like. As a condensed ring formed by bonding two substituents of a 5-membered heterocyclic ring or a 6-membered heterocyclic ring to each other, quinoline ring, isoquinoline ring, cinnoline ring, phthalazine ring, quinoxaline ring, indole ring, benzofuran ring, benzothiophene And rings, benzoimidazole ring, benzoxazole ring, benzothiazole ring, benzisothiazole ring, benzisoxazole ring and the like.

Z is preferably pyridine ring, pyrimidine ring, S-triazine ring, pyridazine ring, pyrazine ring, 1,2,4-thiadiazole ring, 1,3,4-thiadiazole ring, imidazole ring, more preferably pyridine Ring, pyrimidine ring, S-triazine ring, pyridazine ring, pyrazine ring, particularly pyrimidine ring and S-triazine ring from the viewpoints of hue, coloring power and image fastness, and further, at the 4- and 6-positions A pyrimidine ring linked to the nitrogen atom of (1) and an S-triazine ring having an alkoxy group having 1 to 4 carbon atoms at the 2 position are preferable from the viewpoint of hue and image fastness, and particularly 1 to 4 carbon atoms at the 2 position. An S-triazine ring having an alkoxy group is most preferable from the viewpoint of improving the light fastness of a good image.

In formula (1), G ₁ and G ₂ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group (preferably having a carbon number of 1 to 20), or a substituted or unsubstituted aralkyl group (preferably having a carbon number of 7) To 20), substituted or unsubstituted alkenyl group (preferably having a carbon number of 2 to 20), substituted or unsubstituted alkynyl group (preferably having a carbon number of 2 to 20), substituted or unsubstituted aryl group (preferably having a carbon number of 2 to 20), or a substituted or unsubstituted heterocyclic group (preferably having a carbon number of 1 to 20).
G ₁ and G _{2 each} represents a hydrogen atom, methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, t-butyl group, cyclopropyl group, A benzyl group, 2-phenethyl group, vinyl group, allyl group, ethynyl group, propargyl group, phenyl group, p-tolyl group, naphthyl group, pyridyl group, pyrimidinyl group or pyrazinyl group is preferable, and a hydrogen atom or methyl group is preferable. More preferably a group, a phenyl group, a pyridyl group, a pyrimidinyl group or a pyrazinyl group, a linear or branched alkyl group having 1 to 8 carbon atoms in total, a 2-pyridyl group, a 2,6-pyrimidinyl group, 2 It is more preferable to represent a 5, 5-pyrazinyl group or a phenyl group, and an alkyl group having 3 or less carbon atoms in total is more preferable. Furthermore, from the viewpoint of hue and image fastness, a hydrogen atom, a methyl group and a phenyl group are preferable, and among them, a methyl group is particularly preferred from the viewpoint of improving the hue and light fastness.

In formula (1), Y ₁ and Y ₂ each independently represent a hydrogen atom or a substituent.
When Y ₁ and Y ₂ represent a substituent, examples of the substituent include a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, an alkynyl group, an aryl group, a heterocyclic group, a cyano group, a hydroxyl group, a nitro group and an alkoxy Group, aryloxy group, silyloxy group, heterocyclic oxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, amino group, acylamino group, aminocarbonylamino group, alkoxycarbonylamino group, aryloxy Carbonylamino group, sulfamoylamino group, alkyl or arylsulfonylamino group, mercapto group, alkylthio group, arylthio group, heterocyclic thio group, sulfamoyl group, alkyl or arylsulfinyl group, alkyl or arylsulfonyl group Group, acyl group, aryloxycarbonyl group, alkoxycarbonyl group, carbamoyl group, aryl or heterocyclic azo group, imido group, phosphino group, phosphinyl group, phosphinyl oxy group, phosphinyl amino group, silyl group as an example It can be mentioned.
Particularly preferably as Y ₁ and Y ₂ , a hydrogen atom, an alkyl group (eg, methyl group), an aryl group (eg, phenyl group), a heterocyclic group (eg, 2-pyridyl group), an alkylthio group (eg, methylthio group) And more preferably a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a phenyl group or a methylthio group. Further, from the viewpoint of hue and image fastness, a hydrogen atom or a methyl group is preferable. Among them, a hydrogen atom is particularly preferable from the viewpoint of improving the hue and light fastness.

When G ₁ , G ₂ , Y ₁ , Y ₂ , W ₁ , W ₂ , R ₁₁ , R ₁₂ and Z further have a substituent in General Formula (1), the following substituents (Hereinafter sometimes referred to as "substituent J") can be mentioned.

(Substituent J)
As the substituent J, a halogen atom, alkyl group, aralkyl group, alkenyl group, alkynyl group, aryl group, heterocyclic group, cyano group, hydroxyl group, nitro group, alkoxy group, aryloxy group, silyloxy group, heterocyclic oxy Group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxycarbonyloxy group, amino group, acylamino group, aminocarbonylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfamoylamino group, alkyl or Arylsulfonylamino group, mercapto group, alkylthio group, arylthio group, heterocyclic thio group, sulfamoyl group, alkyl or arylsulfinyl group, alkyl or arylsulfonyl group, acyl group, aryloxy group Carbonyl group, an alkoxycarbonyl group, a carbamoyl group, an aryl or heterocyclic azo group, an imido group, a phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, a silyl group. In addition, among the above-mentioned substituents, those having a hydrogen atom may be further substituted with the above-mentioned substituent.
For a more detailed description of the substituent J, reference can be made to the descriptions of [0068] to [0106] in JP-A-2011-74377.

The pigment (P) is preferably a pigment represented by the following general formula (1-1).

In the general formula (1-1),
R _1a , Y ₁ , Y ₂ , R ₁₁ and R ₁₂ each independently represent a hydrogen atom or a substituent.
G ₁ and G ₂ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted group It represents an aryl group or a substituted or unsubstituted heterocyclic group.
W ₁ and W ₂ each independently represent a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.

Y ₁ , Y ₂ , R ₁₁ , R ₁₂ , G ₁ , G ₂ , W ₁ and W ₂ in the general formula (1-1) respectively represent Y ₁ , Y ₂ , R _{11 in the} general formula (1) , R ₁₂ , G ₁ , G ₂ , W ₁ and W ₂ , and the preferred range is also the same.
R _1a in General Formula (1-1) represents a hydrogen atom or a substituent.
Examples of the substituent when R _1a represents a substituent are the same as the examples of the substituent when Y ₁ and Y ₂ represent a substituent, preferably an alkoxy group, and more preferably 1 to 6 carbon atoms It is an alkoxy group of 4, most preferably a methoxy group.
As the substituent when R _1a further has a substituent, the above-mentioned substituent J can be mentioned.

As specific examples of the pigment (P), compounds described in [0124] to [0139] of JP-A-2011-74376 can be referred to.
The pigment (P) is preferably a pigment represented by the following formula (P1), formula (P2), or formula (P3), and is a pigment represented by the following formula (P1) or formula (P2) Is more preferable, and a pigment represented by the following formula (P1) is more preferable.

When crystal polymorphs exist in the pigment used in the present invention, any polymorph may be used, and a mixture of two or more polymorphs may be used. It is preferable to do. That is, it is preferable that the crystal polymorph is not mixed, and the content of the pigment having a single crystal form is 70% to 100%, preferably 80% to 100%, more preferably 90% to 100% of the whole pigment. %, More preferably 95% to 100%, particularly preferably 100%.

The pigment used in the present invention may contain a tautomer of the compound represented by the general formula (1).
General formula (1) is shown in the form of a limit structural formula among several kinds of tautomers which can be taken in chemical structure, but it may be a tautomer other than the described structure, It may be used as a mixture containing the tautomer of.
For example, as a compound represented by the general formula (1), an azo-hydrazone tautomer represented by the following general formula (1 ′) can be considered.

In the general formula (1 ′), R ₁₁ , R ₁₂ , W ₁ , W ₂ , Y ₁ , Y ₂ , G ₁ , G ₂ and Z are R ₁₁ , R ₁₂ , W ₁ , and the like in the general formula (1) It is synonymous with W ₂ , Y ₁ , Y ₂ , G ₁ , G ₂ and Z.

When the compound represented by the general formula (1) has an acid group, some or all of the acid groups may be in salt form, and the salt form compound and the free acid form compound are mixed It may be done. Examples of the salt form include salts of alkali metals such as Na, Li and K, salts of alkaline earth metals such as Mg, Ca and Ba, salts of ammonium which may be substituted with an alkyl group or hydroxyalkyl group, or organic Amine salts may be mentioned. Examples of organic amines include lower alkylamines, hydroxy-substituted lower alkylamines, carboxy-substituted lower alkylamines, and polyamines having 2 to 10 alkyleneimine units having 2 to 4 carbon atoms. In the case of these salt types, the type is not limited to one type and a plurality of types may be mixed.

When a plurality of acid groups are contained in one molecule of the compound represented by the general formula (1), the plurality of acid groups may be in salt form or free acid form and may be different from each other.

The pigment used in the present invention may be a hydrate containing water molecules in crystals.

The pigment used in the present invention is a pigment comprising the compound represented by the general formula (1) or a tautomer thereof, or a salt thereof, and the compound represented by the general formula (1) or the tautomer thereof Or, an assembly of molecules of those salts is in the form of fine particles. The content of the compound represented by the general formula (1) or a tautomer thereof in the pigment, or a salt thereof is preferably 80% by mass or more.
As a method of synthesizing the compound represented by the general formula (1) used in the present invention, and a method of producing a pigment (including post treatments such as solvent sol trimming), [0153] of JP 2011-74376 A The description of [0159] can be referred to.

The content of the pigment (P) in the ink composition of the present invention is preferably 0.1 to 50% by mass, and more preferably 0.5 to 30% by mass with respect to the total mass of the ink composition. Is more preferable, and 1 to 15% by mass is more preferable.

(Polymer dispersant (D))
The ink composition of the present invention contains a polymer dispersant (D) containing a repeating unit having a hydrophilic group and a repeating unit having an aromatic group.
The polymer dispersant (D) is preferably capable of dispersing the pigment (P).

[Repeating unit having a hydrophilic group]
The hydrophilic group in the repeating unit having a hydrophilic group of the polymer dispersant (D) is not particularly limited, and may be a dissociative group or a nonionic hydrophilic group, but the dissociative group Is preferred.
The dissociative group is preferably an anionic dissociative group, more preferably a carboxyl group, a phosphoric acid group or a sulfo group, and still more preferably a carboxyl group.
As the nonionic hydrophilic group, a hydroxyl group or an alkyleneoxy group is preferable.
The repeating unit having a hydrophilic group is preferably a repeating unit derived from a monomer having a hydrophilic group (hydrophilic monomer). In the present specification, the “repeating unit derived from a monomer” refers to a repeating unit (monomer unit) corresponding to the monomer, which the polymer formed by the polymerization reaction of the monomer has.
The monomer having a hydrophilic group is preferably a monomer having a dissociative group and an ethylenic unsaturated bond, or a monomer having a nonionic hydrophilic group and an ethylenic unsaturated bond.
As a monomer which has a dissociative group and an ethylenically unsaturated bond, an unsaturated carboxylic acid monomer, an unsaturated sulfonic acid monomer, an unsaturated phosphoric acid monomer etc. are mentioned, for example.

Specific examples of unsaturated carboxylic acid monomers include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, citraconic acid, 2-methacryloyloxymethyl succinic acid and the like. Specific examples of unsaturated sulfonic acid monomers include styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, 3-sulfopropyl (meth) acrylate, bis- (3-sulfopropyl) -itaconic acid ester, etc. Be Specific examples of unsaturated phosphoric acid monomers include vinyl phosphonic acid, vinyl phosphate, bis (methacryloxyethyl) phosphate, diphenyl-2-acryloyloxyethyl phosphate, diphenyl-2-methacryloyloxyethyl phosphate, and dibutyl -2- Acryloyloxyethyl phosphate etc. are mentioned.
Among the dissociative group-containing monomers, unsaturated carboxylic acid monomers are preferable from the viewpoint of dispersion stability and ejection stability, and at least one of acrylic acid and methacrylic acid is more preferable.

As a monomer having a nonionic hydrophilic group and an ethylenically unsaturated bond, for example, 2-methoxyethyl acrylate, 2- (2-methoxyethoxy) ethyl acrylate, 2- (2-methoxyethoxy) ethyl methacrylate, ethoxy Ethylene glycol containing an ethyleneoxy group such as triethylene glycol methacrylate, methoxypolyethylene glycol (molecular weight 200 to 1000) monomethacrylate, polyethylene glycol (molecular weight 200 to 1000) monomethacrylate, etc., polyethyleneoxy group, propyleneoxy group, or polypropyleneoxy group Unsaturated monomer or hydroxymethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydro Shibuchiru (meth) acrylate, hydroxypentyl (meth) acrylate, and ethylenically unsaturated monomers having a hydroxyl group such as hydroxymethyl (meth) acrylate.

As a repeating unit having a hydrophilic group, either an embodiment containing only a repeating unit having a dissociative group, or an embodiment containing both a repeating unit having a dissociative group and a repeating unit having a nonionic hydrophilic group Is preferred.
In addition, it may be an embodiment in which two or more repeating units having a dissociative group are contained, or an embodiment in which a repeating unit having a dissociative group and a repeating unit having a nonionic hydrophilic group are used in combination.

[Repeating unit having an aromatic group]
The aromatic group in the repeating unit having an aromatic group in the polymer dispersant (D) is not particularly limited, but is preferably an aryl group, more preferably an aryl group having 6 to 30 carbon atoms, carbon More preferably, it is an aryl group of several 6 to 20.
The repeating unit having an aromatic group is preferably a repeating unit derived from a monomer having an aromatic group.
The monomer having an aromatic group is preferably a monomer having an aromatic group and an ethylenically unsaturated bond.

The content ratio (molar ratio) of the repeating unit having a hydrophilic group to the repeating unit having an aromatic group in the polymer dispersant (D) is (the repeating unit having an aromatic group / the repeating unit having a hydrophilic group) And 50/50 to 90/10, and more preferably 60/40 to 80/20.
The content of the repeating unit having a hydrophilic group in the polymer dispersant (D) is preferably 10 to 50 mol%, more preferably 20 to 40 mol%, with respect to all the repeating units of the polymer dispersant (D). It is more preferable that
The content of the repeating unit having an aromatic group in the polymer dispersant (D) is preferably 50 to 90 mol%, more preferably 60 to 80 mol%, with respect to all the repeating units of the polymer dispersant (D). It is more preferable that
The repeating unit having a hydrophilic group and the repeating unit having an aromatic group, which are contained in the polymer dispersant (D), may each be of one type or of two or more types.

The polymer dispersant (D) is preferably a polymer compound having a repeating unit represented by the following general formula (2-1) and a repeating unit represented by the following general formula (2-2).
The repeating unit represented by the following general formula (2-1) is a repeating unit having an aromatic group, and the repeating unit represented by the following general formula (2-2) is a repeating unit having a hydrophilic group is there.

In formula (2-1), R ₁ represents a hydrogen atom, or a methyl group or a substituted methyl group, R ₂ represents a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryloxyalkyl group, or a substituted or unsubstituted group Represents a substituted aryl group.
In general formula (2-2), R ₃ represents a hydrogen atom, or a methyl group or a substituted methyl group. M represents a hydrogen atom or a counter cation.

In the above general formula (2-1), R ₁ represents a hydrogen atom, or a methyl group or a substituted methyl group. R ₁ is preferably a hydrogen atom or a methyl group, more preferably a methyl group. The above-mentioned substituent J is mentioned as a substituent which a substituted methyl group has.

In the above general formula (2-1), R ₂ represents a substituted or unsubstituted aralkyl group, a substituted or unsubstituted aryloxyalkyl group, or a substituted or unsubstituted aryl group.
The substituted or unsubstituted aralkyl group is preferably a substituted or unsubstituted aralkyl group having 7 to 30 carbon atoms, more preferably a substituted or unsubstituted aralkyl group having 7 to 20 carbon atoms, and specifically a benzyl group or a benzyl group It is preferably a 2-phenethyl group.
The substituted or unsubstituted aryloxyalkyl group is preferably a substituted or unsubstituted aryloxyalkyl group having 7 to 30 carbon atoms, and more preferably a substituted or unsubstituted aryloxyalkyl group having 7 to 20 carbon atoms, Preferred is a 2-phenoxyethyl group.
The substituted or unsubstituted aryl group is preferably a substituted or unsubstituted aryl group having 6 to 30 carbon atoms, more preferably a substituted or unsubstituted aryl group having 6 to 20 carbon atoms, and specifically a phenyl group, It is preferably a p-tolyl group or a naphthyl group.
When the aralkyl group, the aryloxyalkyl group, and the aryl group have a substituent, examples of the substituent include the above-mentioned substituent J.

R ₂ is preferably a benzyl group or a 2-phenoxyethyl group, more preferably a benzyl group.

In general formula (2-2), R ₃ represents a hydrogen atom, or a methyl group or a substituted methyl group. R ₃ is preferably a hydrogen atom or a methyl group, more preferably a methyl group. The above-mentioned substituent J is mentioned as a substituent which a substituted methyl group has.

In the general formula (2-2), M represents a hydrogen atom or a counter cation. When M represents a counter cation, examples of the counter cation include alkali metal ions such as sodium ion, lithium ion and potassium ion, ammonium ion and organic cation. Examples of the organic cation include a lower alkyl ammonium cation, a hydroxy substituted lower alkyl ammonium cation, a carboxy substituted lower alkyl ammonium cation and an organic cation having 2 to 10 alkyleneimine units having 2 to 4 carbon atoms.
M in the general formula (2-2) may be all hydrogen atoms, all may be counter cations, or some may be hydrogen atoms and some may be counter cations . Moreover, 1 type of counter cations may be sufficient and 2 or more types may be mixed. The ratio of hydrogen atom to counter cation (hydrogen atom / counter cation molar ratio) is preferably 50/50 to 0/100, and more preferably 30/70 to 0/100.

The polymer compound having the repeating unit represented by the general formula (2-1) and the repeating unit represented by the general formula (2-2) further contains other repeating units in addition to these repeating units It may be As other repeating units, for example, methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, Examples include alkyl (meth) acrylates such as t-butyl (meth) acrylate, hexyl (meth) acrylate and ethylhexyl (meth) acrylate, repeating units derived from styrene or derivatives thereof, repeating units derived from (meth) acrylamide, etc. . When the polymer compound having the repeating unit represented by the general formula (2-1) and the repeating unit represented by the general formula (2-2) contains other repeating units, the content of the other repeating units The preferred is 0.1 to 20 mol%, based on the total repeating units of the above-mentioned polymer compound.

The polymer dispersant (D) can be synthesized by a known method (for example, the method described in JP-A-2011-74377, JP-A-2012-25866, etc.).

The polymer dispersant (D) is preferably a water soluble polymer. In the present invention, the water-soluble polymer is a polymer having a dissolved amount of 5 g or more when it is dissolved in 100 g of water at 25 ° C. after drying the polymer at 105 ° C. for 2 hours. The amount of dissolution is the amount of dissolution when 100% neutralization is carried out with sodium hydroxide or acetic acid, depending on the type of salt forming group of the water-soluble polymer.

The weight average molecular weight (Mw) of the polymer dispersant (D) is preferably 5,000 to 100,000, more preferably 7,000 to 70000, and still more preferably 7,000 to 50,000. When the weight average molecular weight of the polymer dispersant (D) is 5,000 or more, the image quality of the print is excellent. When the weight average molecular weight of the polymer dispersant (D) is 100,000 or less, it is possible to prevent a decrease in storage stability, which is preferable.
In the present specification, the weight average molecular weight of the polymer dispersant is a polystyrene conversion value measured by GPC (gel permeation chromatography) method. GPC uses HLC-8220 (manufactured by Tosoh Corp.), and TSK gel GMHXL, TSK gel G4000 HXL, and TSK gel G2000 HXL (manufactured by Tosoh Corp., 7.8 mm ID × 30.0 cm) as columns as columns. It measured using THF (tetrahydrofuran).

The content of the polymer dispersant (D) in the ink composition of the present invention is preferably 10 to 100 parts by mass, and more preferably 20 to 80 parts by mass with respect to 100 parts by mass of the pigment (P). And 20 to 60 parts by mass. When the content of the polymer dispersant (D) is 10 parts by mass or more with respect to 100 parts by mass of the pigment (P), the pigment can be efficiently dispersed, which is preferable. Moreover, when content of a polymer dispersing agent (D) is 100 mass parts or less with respect to 100 mass parts of pigments (P), since productivity is improved and it is economical, it is preferable.
The polymer dispersant (D) may be used alone or in combination of two or more.

(Polymer particles (B))
The ink composition of the present invention contains a polymer particle (B) containing a repeating unit having a hydrophilic group and a repeating unit having a cyclic aliphatic group.
The polymer particles (B) are present in the form of particles in the ink composition of the present invention, and are particles dispersed in water (latex) contained in the ink composition of the present invention.
The polymer particles (B) increase the strength of the image by forming a film at the time of ink drying after image formation, and improve the performance such as scratch resistance and light resistance of the print, and the polymer dispersant described above It is different from (D).
The polymer dispersant (D) is preferably adsorbed to the pigment (P) from the viewpoint of dispersion stability of the pigment to form particles, but the polymer particles (B) are particles of only the polymer from the viewpoint of film formation. The polymer particles (B) do not contain the pigment (P).
Hereinafter, the polymer constituting the polymer particles (B) is also referred to as polymer (B).

The main chain skeleton of the polymer (B) in the present invention is not particularly limited, but from the viewpoint of the dispersion stability of the polymer particles (B), vinyl polymers are preferred, and (meth) acrylic polymers preferable. Here, the (meth) acrylic polymer means a polymer containing at least one of a repeating unit derived from a methacrylic acid derivative and a repeating unit derived from an acrylic acid derivative.

The polymer particles (B) are preferably self-dispersible polymer particles. Self-dispersible polymer particles refer to particles of a water-insoluble polymer that can be dispersed in water due to the functional groups of the polymer itself (in particular the acidic groups or salts thereof).
Here, the dispersed state includes an emulsified state in which a water-insoluble polymer is dispersed in water in a liquid state (emulsion) and a dispersed state in which a water-insoluble polymer is dispersed in water in a solid state (suspension) It is
The self-dispersible polymer particles in the present invention are preferably self-dispersible polymer particles in which the water-insoluble polymer can be dispersed in a solid state from the viewpoint of the abrasion resistance of the printed matter. In the present invention, a water-insoluble polymer refers to a polymer whose dissolved amount is less than 5 g when it is dissolved in 100 g of water at 25 ° C. after drying the polymer at 105 ° C. for 2 hours. Is preferably 2 g or less, more preferably 1 g or less. The amount of dissolution is the amount of dissolution when 100% neutralization is carried out with sodium hydroxide or acetic acid, depending on the type of salt forming groups of the water-insoluble polymer.

[Repeating unit having a hydrophilic group]
The description about the repeating unit which has a hydrophilic group of polymer particle (B) is the same as that of the above-mentioned polymer dispersing agent (D), and its preferable range is also the same.

[Repeating unit having a cyclic aliphatic group]
The cyclic aliphatic group in the repeating unit having a cyclic aliphatic group of the polymer particle (B) is not particularly limited, and examples thereof include a monocyclic aliphatic hydrocarbon group and a polycyclic aliphatic hydrocarbon group, and preferably It is a polycyclic aliphatic hydrocarbon group. The polycyclic aliphatic hydrocarbon group represents a monovalent substituent having a structure in which two or more non-aromatic hydrocarbon rings are bonded to each other.
The cyclic aliphatic group includes, for example, cycloalkyl group such as cyclopentyl group and cyclohexyl group, cycloalkenyl group, bicyclohexyl group, norbornyl group, isobornyl group, dicyclopentanyl group, dicyclopentenyl group, adamantyl group, decahydro Naphthalenyl group, perhydrofluorenyl group, tricyclo [5.2.1.02,6] decanyl group, bicyclo [4.3.0] nonane and the like can be mentioned.

The cyclic aliphatic group may further have a substituent. As a substituent, for example, an alkyl group, an alkenyl group, an aryl group, an aralkyl group, an alkoxy group, a hydroxyl group, a primary amino group, a secondary amino group, a tertiary amino group, an alkyl or aryl carbonyl group, a cyano group, etc. Can be mentioned.
The cyclic aliphatic group may further form a condensed ring.
The cyclic aliphatic group preferably has 5 to 20 carbon atoms from the viewpoint of viscosity or solubility.

The repeating unit having a cyclic aliphatic group is preferably a repeating unit derived from a monomer having a cyclic aliphatic group.
The monomer having a cyclic aliphatic group is preferably a monomer having a cyclic aliphatic group and an ethylenically unsaturated bond, and a monomer having a cyclic aliphatic group and a (meth) acryloyl group (hereinafter referred to as “alicyclic” It is more preferable that it is (meth) acrylate.
Specific examples of the alicyclic (meth) acrylate are shown below, but are not limited thereto.
As monocyclic (meth) acrylate, cyclopropyl (meth) acrylate, cyclobutyl (meth) acrylate, cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, cyclooctyl (meth) acrylate, cyclononyl Examples thereof include cycloalkyl (meth) acrylate having a carbon number of 3 to 10 of the cycloalkyl group such as (meth) acrylate and cyclodecyl (meth) acrylate.
Examples of bicyclic (meth) acrylates include isobornyl (meth) acrylate and norbornyl (meth) acrylate.
Examples of tricyclic (meth) acrylates include adamantyl (meth) acrylate, dicyclopentanyl (meth) acrylate, and dicyclopentenyl oxyethyl (meth) acrylate.
These can be used alone or in combination of two or more.

Among these, at least one of bicyclic (meth) acrylate or polycyclic (meth) acrylate of three or more rings is preferable, and isobornyl (meth) acrylate, adamantyl (meth) acrylate, and dicyclopenta More preferably, it is at least one selected from nyl (meth) acrylates.
The repeating unit having a cyclic aliphatic group contained in the polymer particle (B) is a repeating unit derived from at least one selected from isobornyl (meth) acrylate, adamantyl (meth) acrylate, and dicyclopentanyl (meth) acrylate The abrasion resistance of the print obtained using the ink composition of the present invention is particularly good.

The content of the repeating unit having a cyclic aliphatic group contained in the polymer particle (B) is preferably 10 to 90 mol%, and more preferably 20 to 80 mol based on all repeating units contained in the polymer particle (B). %, More preferably 30 to 70% by mole.
By setting the content of the repeating unit having a cyclic aliphatic group to 10 mol% or more, the light resistance of the print can be improved. On the other hand, the stability of the polymer particle (B) is improved by setting the content of the repeating unit having a cyclic aliphatic group to 90 mol% or less.

The content of the repeating unit having a hydrophilic group in the polymer particle (B) is preferably 5 to 30 mol%, and is 5 to 20 mol%, with respect to all the repeating units of the polymer particle (B). Is more preferred.
The repeating unit having a hydrophilic group and the repeating unit having a cyclic aliphatic group, which are contained in the polymer particle (B), may each be of one type or of two or more types.

The polymer particle (B) can further contain other repeating units, as needed, in addition to the repeating units having a hydrophilic group and the repeating units having a cyclic aliphatic group. There is no restriction | limiting in particular as another repeating unit, The repeating unit derived from a well-known monomer is mentioned.
Specific examples of the monomer forming the other repeating unit include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, Alkyl (meth) acrylates such as isobutyl (meth) acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, ethylhexyl (meth) acrylate; and aromatic groups such as benzyl (meth) acrylate and phenoxyethyl (meth) acrylate Containing (meth) acrylates; styrenes such as styrene, α-methylstyrene, chlorostyrene and the like.

As monomers forming other repeating units, from the viewpoints of flexibility of polymer skeleton and easiness of control of glass transition temperature (Tg) and dispersion stability of self-dispersing polymer, carbon number is 1 to 8 It is preferably at least one kind of (meth) acrylate containing a chain alkyl group, more preferably a (meth) acrylate having a chain alkyl group having 1 to 4 carbon atoms, and particularly preferably methyl (meth) ) Acrylate or ethyl (meth) acrylate, most preferably methyl (meth) acrylate. Here, a chain alkyl group means an alkyl group having a linear or branched chain.

The other repeating units may be used alone or in combination of two or more. When the polymer particles (B) contain other repeating units, the content is preferably 10 to 80 mol%, more preferably 15 to all repeating units contained in the polymer particles (B). It is up to 75 mol%, particularly preferably 20 to 70 mol%.

The polymer (B) preferably has a repeating unit represented by the following general formula (3-1) and a repeating unit represented by the following general formula (3-2).
The repeating unit represented by the following general formula (3-1) is a repeating unit having a cyclic aliphatic group, and the repeating unit represented by the following general formula (3-2) is a repeating unit having a hydrophilic group It is.

In general formula (3-1), R ₄ represents a hydrogen atom, or a methyl group or a substituted methyl group, and RA represents a cyclic aliphatic group.
In general formula (3-2), R ₅ represents a hydrogen atom, or a methyl group or a substituted methyl group. M ₁ represents a hydrogen atom or a counter cation.

R ₄ in the general formula (3-1) has the same meaning as R ₁ in the general formula (2-1), and the preferred range is also the same.

In the above general formula (3-1), RA represents a cyclic aliphatic group, specific examples and preferred ranges are the same as those described above, and in particular, is an isobornyl group, an adamantyl group or a dicyclopentanyl group Is preferred. That is, the repeating unit having a cyclic aliphatic group contained in the polymer particle (B) is a repeating unit represented by the following general formula (b-1), a repeating unit represented by the following general formula (b-2), And at least one selected from the group consisting of repeating units represented by the following general formula (b-3).

R _1b to R _3b in the general formulas (b-1) to (b-3) represent a hydrogen atom or a methyl group.

R ₅ and M ₁ in the general formula (3-2) have the same meanings as R ₃ and M in the general formula (2-2), and specific examples and preferred ranges are also the same.

The polymer (B) is added to the repeating unit represented by the above general formula (3-1) and the repeating unit represented by the above general formula (3-2), and is further represented by the following general formula (3-3) It may have a repeating unit.

In formula (3-3), R ₆ represents a hydrogen atom, or a methyl group or a substituted methyl group, and R ₇ represents a substituted or unsubstituted alkyl group.

R ₆ in the general formula (3-3) has the same meaning as R ₁ in the general formula (2-1), and the preferred range is also the same.
R ₇ in the above general formula (3-3) represents a substituted or unsubstituted alkyl group, preferably a linear alkyl group having 1 to 8 carbon atoms, and a linear alkyl having 1 to 4 carbon atoms It is more preferable to represent a group, more preferably a methyl group or an ethyl group, and most preferably a methyl group.

The polymer (B) is a repeating unit represented by the above general formula (3-1), a repeating unit represented by the above general formula (3-2), and a repetition represented by the above general formula (3-3) It is preferred to contain a unit. In this case, the repeating unit represented by the general formula (3-1) is contained in an amount of 10 to 70 mol% based on all repeating units, and the repeating unit represented by the general formula (3-2) is all repeating units The repeating unit represented by the above general formula (3-3) is preferably contained in an amount of 5 to 30% by mole, and preferably 10 to 80% by mole with respect to all the repeating units. Containing 20 to 60 mol% of the repeating unit represented by the above with respect to all the repeating units, and containing 5 to 20 mol% of the repeating units represented by the above general formula (3-2) with respect to all the repeating units It is more preferable that the repeating unit represented by the general formula (3-3) is contained in an amount of 20 to 70% by mole based on all repeating units.
In addition, a polymer (B) is represented by the repeating unit represented by the said General formula (3-1), the repeating unit represented by the said General formula (3-2), and the said General formula (3-3). The total content of these content rates is 100 mol% when it consists only of repeating units, and when the content of other repeating units is further included in addition to these, the total content of all the repeating units is 100 mol%. Become.

The weight average molecular weight (Mw) of the polymer (B) is preferably 3,000 to 200,000, more preferably 10,000 to 200,000, and still more preferably 30,000 to 150,000. By setting the weight average molecular weight to 3000 or more, the amount of water soluble component can be effectively suppressed. In addition, the self-dispersion stability can be enhanced by setting the weight average molecular weight to at most 200,000.
The weight average molecular weight of the polymer (B) is measured by the same method as the weight average molecular weight of the polymer dispersant (D).

The glass transition temperature (Tg) of the polymer (B) is preferably 80 to 200 ° C., and more preferably 120 to 180 ° C. from the viewpoint of the abrasion resistance.

The glass transition temperature (Tg) of a polymer (B) applies the measurement Tg obtained by measurement. Specifically, the measured Tg means a value measured under a normal measurement condition using a differential scanning calorimeter (DSC) EXSTAR 6220 manufactured by SII Nano Technology Co., Ltd.

However, when measurement is difficult due to decomposition of the polymer, etc., the calculated Tg calculated by the following formula is applied.
The calculated Tg is calculated by the following equation (α1).
1 / Tg = Σ (Xi / Tgi) (α1)
Here, in the polymer to be calculated, n kinds of monomer components from i = 1 to n are copolymerized. Xi is the weight fraction of the ith monomer (ΣXi = 1), and Tgi is the glass transition temperature (absolute temperature) of the homopolymer of the ith monomer. Is the sum of i = 1 to n. The value of the homopolymer glass transition temperature (Tgi) of each monomer is the value of Polymer Handbook (3rd Edition) (J. Brandrup, E. H. Immergut (Wiley-Interscience, 1989)).

The self-dispersing polymer in the present invention preferably has a degree of neutralization of 40 to 60%, more preferably 45 to 55%, and still more preferably 47 to 53% from the viewpoint of stably producing a self-dispersing polymer. Is particularly preferred.
In the present invention, the degree of neutralization refers to the mol% of the added alkali when the dissociative group contained in the self-dispersing polymer chain is 100 mol% in the production of the self-dispersing polymer.

The polymer particles (B) are preferably prepared as a dispersion dispersed in water. The dispersion liquid of the polymer particles (B) can be prepared by a known method such as phase inversion emulsification method or emulsion polymerization method (for example, the method described in JP-A-2011-46908 etc.).

The volume average particle size (also simply referred to as “average particle size”) of the polymer particles (B) is preferably 0.1 to 34 nm, more preferably 0.1 to 30 nm, and 1.4 to 4 30 nm is more preferable, and 1.4 to 23 nm is particularly preferable. In particular, the volume average particle size of the polymer particles (B) is preferably 1.4 nm or more because the temporal stability of the ink composition is good, and the volume average particle size of the polymer particles (B) is 30 nm or less It is preferable because the gloss of a printed matter obtained using the ink composition is excellent because fusion of the polymer particles (B) occurs densely.
The particle size distribution of the polymer particles (B) is not particularly limited, and may be either a broad particle size distribution or a monodispersed particle size distribution. In addition, two or more types of polymer particles (B) may be mixed and used.
The average particle size and particle size distribution of the polymer particles (B) can be measured by a dynamic light scattering method using an ultrafine particle size distribution analyzer Nanotrac UPA-EX150 (manufactured by Nikkiso Co., Ltd.).

The content of the polymer particles (B) in the ink composition of the present invention is preferably 1 to 30% by mass, more preferably 2 to 20% by mass, based on the total mass of the ink composition, and 2 It is more preferable that the content be 10% by mass.
The polymer particles (B) may be used alone or in combination of two or more.

From the viewpoint of abrasion resistance and gloss, the content W of the ratio of the content of W _P, the content of W _B of the polymer particles (B) of the pigment in the ink composition of the present invention (P) (Pigment (P) is preferably a polymer particle with respect to _P (B) ratio of content of _{W B} of) _W B / _{W P} is 1 or more, more preferably 1.5 to 5, 1.5 to 3 It is further preferred that When W _B / W _P is 1 or more, the gloss is considered to be improved because the film forming property of the polymer particles (B) is improved.
Where W _P is the ratio (% by mass) of the mass of the pigment (P) to the total mass of the ink composition, and W _B is the ratio (% by mass) of the mass of the polymer particles (B) to the total mass of the ink composition It is.
In addition, from the viewpoint of the ink ejection property, W _P + W _B which is the sum of the content ratio W _P of the pigment (P) in the ink composition and the content ratio W _B of the polymer particles (B) is 12% by mass or less The content is preferably 2 to 12% by mass, and more preferably 4 to 10% by mass.

(water)
The ink composition of the present invention contains water.
The water may be tap water or well water, and is not particularly limited. For example, pure water or ultrapure water such as ion exchanged water, ultrafiltered water, reverse osmosis water, distilled water or the like is preferable. Furthermore, it is also preferable to use water sterilized by ultraviolet treatment, hydrogen peroxide solution treatment or the like for the purpose of preventing the generation of mold and bacteria.
The content of water in the ink composition is preferably 20 to 98% by mass, and more preferably 30 to 90% by mass, with respect to the total mass of the ink composition.

(Water-soluble organic solvent)
The ink composition of the present invention contains water as a medium, and preferably further contains a water-soluble organic solvent.
The water-soluble organic solvent is preferably 10 g / 100 g-H ₂ O or more as water solubility at 25 ° C., more preferably 20 g / 100 g-H ₂ O or more, and mixed with water at an arbitrary ratio Are particularly preferred. Examples of the water-soluble organic solvent include alcohol solvents, amide solvents and nitrile solvents, and glycerin, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, 1,3-propanediol, 1,4-butanediol, Preferably, it is at least one selected from 1,2-hexanediol and diglycerol.
The water-soluble organic solvent may be used alone or in combination of two or more.

The content of the water-soluble organic solvent in the ink composition of the present invention is preferably 0.1 to 50% by mass, and more preferably 1 to 40% by mass, based on the total mass of the ink composition. Preferably, it is 5 to 30% by mass.

(Other ingredients)
The ink composition of the present invention may contain other components in addition to the pigment (P), the polymer dispersant (D), the polymer particles (B), water, and the water-soluble organic solvent. Other components include organic solvents other than water-soluble organic solvents (also referred to as "other organic solvents"), preservatives, surfactants, anti-drying agents (wetting agents), anti-fading agents, emulsion stabilizers, permeation promotion Agents, UV absorbers, pH adjusters, surface tension adjusters, antifoamers, viscosity adjusters, dispersants, dispersion stabilizers, rust inhibitors, chelating agents, and other known additives (Japanese Patent Laid-Open No. 2003-306623) Described in the above.

(Other organic solvents)
As other organic solvents, alcohol solvents, ketone solvents and ether solvents are preferably mentioned, and those having a solubility in water of 50% by mass or less and 10% by mass or more at 20 ° C. are preferable.
Examples of alcohol solvents include ethanol, isopropanol, n-butanol, tertiary butanol, isobutanol, diacetone alcohol and the like. Examples of ketone solvents include acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone and the like. Examples of ether solvents include dibutyl ether, tetrahydrofuran, dioxane and the like. Of these solvents, isopropanol, acetone and methyl ethyl ketone are preferred, in particular methyl ethyl ketone. These solvents may be used alone or in combination of two or more.

When another organic solvent is used, the content of the other organic solvent is preferably 0.1 to 10% by mass with respect to the total mass of the ink composition.

(Preservative)
Preservatives refer to those having a function of preventing the development and growth of microorganisms, particularly bacteria and fungi (molds).
Examples of preservatives include inorganic preservatives (eg, silver ion-containing substances) or salts containing heavy metal ions. As organic preservatives, quaternary ammonium salts (tetrabutyl ammonium chloride, cetyl pyridinium chloride, benzyl trimethyl ammonium chloride, etc.), phenol derivatives (phenol, cresol, butyl phenol, xylenol, bisphenol etc.), phenoxy ether derivatives (Phenoxyethanol etc.), Heterocyclic compounds (benzotriazole, proxel (PROXEL), 1,2-benzoisothiazolin-3-one etc.), Acid amides, Carbamic acids, Carbamates, Amidines, guanidines, Pyridines (sodium pyridine) Thion-1-oxides etc.), diazines, triazines, pyrroles, imidazoles, oxazoles, oxazines, thiazoles, thiadiazines, thioureas, thiosemical Zoids, dithiocarbamates, sulfides, sulfoxides, sulfones, sulfamides, antibiotics (penicillin, tetracycline etc.), sodium dehydroacetate, sodium benzoate, ethyl p-hydroxybenzoic acid ester, and salts thereof Various ones can be used.
In addition, as preservatives, use those described in the Microbicidal and Antifungal Micro Handbook (Technological Journal Publishing Co., Ltd .: 1986) and the Microbial and Antifungal Agent Encyclopedia (edited by the editorial board of the Japanese Society of Antibacterial and Antifungal Agents) Can.
The content of the preservative can be used in a wide range, but is preferably 0.01 to 20% by mass, and more preferably 0.1 to 10% by mass, with respect to the pigment (P). % By mass is more preferred.

[Method of producing ink composition]
The method for producing the ink composition of the present invention is not particularly limited, and the ink composition can be produced by a known method. However, a pigment dispersion in which the pigment (P) is dispersed in water with a polymer dispersant (D) Separately, a dispersion of polymer particles (B) is produced, and a method of producing an ink composition by mixing the dispersion of pigment and the dispersion of polymer particles (B) with other components as needed. preferable.

(Method of producing pigment dispersion)
The method for producing the pigment dispersion is not particularly limited, and can be produced by a known method.
Step (A): obtaining a composition containing pigment (P), polymer dispersant (D), water-soluble organic solvent, and water, and
Step (B): It is preferable to include the step of dispersing the pigment (P) in the composition obtained in step (A) using a disperser to obtain a pigment dispersion.
Each process will be described below.

<Step (A)>
In the step (A), the respective components are preferably mixed by a known mixing method. The mixing method is not particularly limited.
Further, the mixing temperature and the mixing time in the step (A) are not particularly limited, and may be appropriately selected according to the progress of desired mixing.
In the step (A), the components may be mixed in any order.
In the step (A), if necessary, other components such as organic solvents other than the above-mentioned water-soluble organic solvent, preservatives and the like may be added.

<Step (B)>
Step (B) is a step of dispersing the pigment (P) in the composition obtained in step (A) using a disperser to obtain a pigment dispersion.
In the step (B), the composition obtained in the step (A) is stirred by a disperser or the like to disperse the pigment in the composition to obtain a pigment dispersion.
In addition, although a composition obtained at a process (A) is used at a process (B), a process (A) and a process (B) may be performed simultaneously. As an example in case a process (A) and a process (B) are performed simultaneously, the pigment (P) used by the disperser in process (A), a polymer dispersing agent (D), a water-soluble organic solvent, water, and If necessary, other components may be added to obtain the composition of step (A) and simultaneously disperse by a disperser.

In the step (B), the pigment (P) is preferably dispersed such that the volume average particle size of the pigment (P) falls within a desired range, and the pigment (P) is dispersed such that the volume average particle size is 100 nm or less. Is more preferred.

The method of dispersing the pigment in step (B) can be carried out using a known dispersing machine, and is not particularly limited. In the step (B), for example, a mill system (eg, colloid mill, ball mill, sand mill, bead mill, attritor, roll mill, jet mill, paint shaker, agitator mill, etc.), ultrasonic system (ultrasonic homogenizer), high pressure emulsification Dispersion method (high pressure homogenizer; as a commercially available apparatus, Gorlin homogenizer, Microfluidizer, DeBEE 2000, etc.), high-speed stirring type disperser, etc. can be used.
Among these, a mill system is preferable, a medium dispersion system, that is, a disperser using a dispersion medium (colloid mill, ball mill, sand mill, bead mill, etc.) is more preferable, and a bead mill is more preferable.

<Step (C)>
In the method for producing a pigment dispersion, as the step (C), a step of heating the pigment dispersion obtained in the step (B) after the step (B) (hereinafter, also simply referred to as a “heat treatment step”). It is preferable to further include By having the heat treatment step, the relationship between the pigment (P) and the polymer dispersant (D) in the pigment dispersion becomes more stable.
As heating temperature in a heat treatment process, 40 ° C or more and 95 ° C or less are preferred, 50 ° C or more and 95 ° C or less are more preferable, and 60 ° C or more and 95 ° C or less are still more preferable.
Moreover, as heating time in a heat treatment process, 5 minutes or more are preferable, 5 minutes or more and 24 hours or less are more preferable, and 30 minutes or more and 12 hours or less are still more preferable.
In the heat treatment step, heat treatment may be performed while stirring.

The method for producing a pigment dispersion may include other steps in addition to the above steps (A) to (C). As another process, a pH adjustment process, a disinfection process, a solvent removal process, a deionization process, a centrifugation process, a filtration process etc. are mentioned, for example.

(Method of producing dispersion of polymer particles (B))
The dispersion liquid of the polymer particles (B) can be prepared by the known method (for example, the method described in JP-A-2011-46908 etc.) as described above.

[Ink jet ink]
The ink composition of the present invention is preferably for inkjet. That is, the ink composition of the present invention is preferably an inkjet ink.

[Image formation method]
The image forming method of the present invention has a step of applying the ink composition of the present invention onto a recording medium by an ink jet method. As the inkjet method, a known inkjet method can be used, and as the recording medium, a known recording medium can be used.

Hereinafter, the present invention will be more specifically described by way of examples. The materials, amounts used, proportions, treatment contents, treatment procedures and the like shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Accordingly, the scope of the present invention is not limited to the specific examples shown below. In addition, unless there is particular notice, "part" and "%" are mass references.

(Synthesis of Polymer Dispersant (D1))
To 276.8 g of 1,2-hexanediol, 9.0 g of Perbutyl O (manufactured by NOF Corporation) was added and stirred to prepare an initiator solution (I). Separately from this, 438.0 g of benzyl methacrylate, 92.0 g of methacrylic acid, and 23.5 g of 2-ethylhexyl 3-mercaptopropionate were added to 207.6 g of 1,2-hexanediol and stirred to prepare a monomer solution (M) did.
359.5 g of 1,2-hexanediol was charged into a 3 L three-necked flask, and the temperature was raised to an internal temperature of 85 ° C. under a nitrogen stream, and dropwise addition of the initiator solution (I) and the monomer solution (M) was started simultaneously. The initiator solution (I) was dropped over 5 hours, and the monomer solution (M) was dropped over 4 hours. After completion of the addition of the initiator solution (I), the mixture is stirred at 85 ° C. for 2 hours and then cooled to 70 ° C., to which 96.0 g of 50% aqueous potassium hydroxide solution, 65.2 g of water, 1, 2 40.7 g of hexanediol was added and stirred at 70 ° C. for 2 hours. 1367 g of water was added thereto, and the mixture was further stirred for 2 hours to obtain a 1,2-hexanediol solution of a polymer dispersant (D1). The solid content of the 1,2-hexanediol solution of the polymer dispersant (D1) was 19.8% by mass, and the weight average molecular weight of the polymer dispersant (D1) was 8,500.

The polymer dispersant (D1) is a polymer compound of the following structure. The ratio of repeating units is a molar ratio.

(Synthesis of Polymer Dispersant (D2))
Polymer dispersion in the same manner as polymer dispersant (D1) except that in the synthesis of polymer dispersant (D1), the compositions of monomer solution (M) and initiator solution (I) were changed as described in Table 1. The triethylene glycol solution of an agent (D2) was obtained. The solid content of the triethylene glycol solution of the polymer dispersant (D2) was 19.4% by mass, and the weight average molecular weight of the polymer dispersant (D2) was 9,000.

The polymer dispersant (D2) is a polymer compound of the following structure. The ratio of repeating units is a molar ratio.

“Perbutyl-O” is a polymerization initiator manufactured by NOF Corporation, and “V-601” is a polymerization initiator manufactured by Wako Pure Chemical Industries, Ltd.

Example 1
<Step (A)>
The components shown below were mixed to obtain a composition (1) containing a pigment, a polymer dispersant, 1,2-hexanediol, and water. As a 1,2-hexanediol solution of the following polymer dispersant (D1), the one obtained in the synthesis of the above-mentioned polymer dispersant (D1) was used. The content of 1,2-hexanediol in the composition (1) was 16.7% by mass.
(Composition of composition (1))
Pigment represented by formula (P1) 18.2 g
Polymer solution (D1) in 1,2-hexanediol solution 46.0 g
Ultra pure water 65.8g

<Step (B)>
The composition (1) is put into a pulverization container in the disperser together with zirconia beads having a diameter of 0.1 mm using Sand Grinder Mill (manufactured by Imex Co., Ltd.) as a disperser, and the mixture is stirred for 5 hours. The pigment was dispersed. After completion of the dispersion, it was confirmed that the volume average particle diameter of the dispersion became 90 nm or less, the beads were separated using a filter cloth, and the dispersion was washed with ion exchanged water. Furthermore, pigment dispersion liquid (1) was obtained by diluting with ultrapure water so that the pigment concentration would be 10% by mass.

<Step (C)>
The pigment dispersion (1) obtained in step (B) was heated at 90 ° C. for 12 hours.

Centrifugation process
After step (C), coarse particles in pigment dispersion (1) were sedimented using a centrifuge. The precipitated coarse particles are removed through a filter with a pore size of 0.3 μm, and sufficiently washed with ultrapure water using an ultrafiltration membrane with a molecular weight cut off of 50000, and the obtained dispersion liquid at 70 ° C. for 1 hour Heated. Thereafter, the resultant was cooled to 25 ° C., coarse particles were removed again through a filter with a pore diameter of 1.0 μm, and a pigment dispersion (1S) having a pigment concentration of 10% by mass was obtained.

Preparation of Dispersion of Polymer Particles (B1)
In a 2-liter three-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet, 560.0 g of methyl ethyl ketone was charged, and the temperature was raised to 87 ° C. 220.4 g of methyl methacrylate, 301.6 g of isobornyl methacrylate, 58.0 g of methacrylic acid, 108 g of methyl ethyl ketone, and “V-601” (Wako Pure Chemical Industries, Ltd. while maintaining the reflux state in the reaction vessel (hereinafter, reflux until the reaction is completed) A mixed solution consisting of 2.32 g of Medicinal Products Co., Ltd. was dropped at a constant speed so that the dropping was completed in 2 hours. After completion of the dropwise addition, after stirring for 1 hour, a solution consisting of (1) 1.16 g of "V-601" and 6.4 g of methyl ethyl ketone was added, and stirring was performed for 2 hours. Subsequently, the step (1) was repeated four times, and a solution consisting of 1.16 g of “V-601” and 6.4 g of methyl ethyl ketone was further added, and stirring was continued for 3 hours. After completion of the polymerization reaction, the temperature of the solution was lowered to 65 ° C., and 163.0 g of isopropanol was added and allowed to cool. The weight average molecular weight (Mw) of the obtained copolymer was 63,000, and the acid value was 65.1 (mg KOH / g).

Next, 317.3 g (solid content concentration 41.0%) of the obtained polymerization solution was weighed, and 46.4 g of isopropanol, 1.65 g of a 20% aqueous solution of maleic anhydride (water-soluble acidic compound, relative to copolymer) 40.77 g of 2 mol / L NaOH aqueous solution was added as maleic acid (equivalent to 0.3%), and the temperature in the reaction vessel was raised to 70 ° C. Next, 380 g of distilled water was dropped at a rate of 10 ml / min to disperse in water (dispersion step).
After that, 287.0 g in total of isopropanol, methyl ethyl ketone and distilled water are distilled off (vacuum removal step) while maintaining the reaction vessel temperature at 70 ° C. for 1.5 hours under a reduced pressure (solvent removal step), Proxel GXL (S) A.) (440 ppm as benzisothiazolin-3-one with respect to polymer solids) was added. Thereafter, filtration was carried out with a 1 μm filter, and the filtrate was recovered to obtain a dispersion liquid of polymer particles (B1) which is a self-dispersing polymer particle having a solid content concentration of 26.5% by mass. The obtained polymer particles (B1) were diluted with ion-exchanged water, and the physical properties of a 25.0 mass% solution were measured. As a result, pH 7.8, electric conductivity 461 mS / m, viscosity 14.8 mPa · s, volume average particle The diameter was 2.8 nm.
Thus, a dispersion of polymer particles (B1) was obtained.

<Measurement of glass transition temperature (Tg)>
It was 160 degreeC when the glass transition temperature (Tg (B1)) of the obtained polymer particle (B1) was measured by the following method.
The polymer solution after polymerization was dried under reduced pressure at 50 ° C. for 4 hours, in particular in an amount of 0.5 g of solid content, to obtain a polymer solid content. The Tg of the obtained polymer solid content was measured by a differential scanning calorimeter (DSC) EXSTAR 6220 manufactured by SII Nano Technology Inc. The measurement conditions were as follows: a sample amount of 5 mg was sealed in an aluminum pan, and the peak top value of DSC of measurement data at the second temperature rise in a nitrogen atmosphere under the following temperature profile was used as Tg.
The glass transition temperatures (Tg (B2) to Tg (B6)) of the polymer particles (B2) to (B6) were also measured in the same manner.
First cooling 30 ° C → -50 ° C (50 ° C / min cooling)
1st temperature rise -50 ° C → 220 ° C (20 ° C / min)
Second cooling 120 ° C → -50 ° C (cooling at 50 ° C / min)
Second temperature rise -50 ° C → 220 ° C (20 ° C / min)

<Measurement of Volume Average Particle Size (Mv)>
The dispersion liquid of the obtained polymer particles (B1) is appropriately diluted to a concentration suitable for measurement (loading index is in the range of 0.1 to 10), and the ultrafine particle size distribution analyzer Nanotrack UPA-EX150 (Nikkiso Co., Ltd.) Volume average particle size was measured under the same measurement conditions by a dynamic light scattering method. That is, the measurement was carried out under the conditions of particle permeability: transmission, particle refractive index: 1.51, particle shape: non-spherical, density: 1.2 g / cm ³ , solvent: water, cell temperature: 18 to 25 ° C.

Preparation of Ink Composition
The following components were mixed and stirred sufficiently, and passed through a filter with a pore size of 0.8 μm to prepare an ink composition (1).
(Composition of Ink Composition (1))
Pigment dispersion (1S) 30.0 g
Dispersion of polymer particles (B1) 3.8 g
Ultra pure water 38.5 g
2-Pyrrolidinone 3.1 g
15.0 g of glycerol
1,2-hexanediol 4.0 g
Ethylene glycol 5.1 g
Surfynol 465 0.5 g

Surfynol 465 is a surfactant manufactured by Nisshin Chemical Industry Co., Ltd.

(Examples 2 to 20, Comparative Examples 1 to 3, 5 and 6)
The type of pigment used and the content in the ink composition, the type of the polymer dispersant, and the type of polymer particles and the content and the volume average particle size in the ink composition are changed as shown in Table 2 below. Ink compositions (2) to (20), (R1) to (R3), (R5) and (R6) were prepared in the same manner as in Example 1. W _P is the content of the pigment in the ink composition, is expressed as a ratio (mass%) of the mass of the pigment to the total mass of the ink composition, and W _B is the content of the polymer particles in the ink composition It is represented by the ratio (mass%) of the mass of polymer particles (B) to the total mass of the ink composition. The content of each component in the ink composition was changed by adjusting the amount of the pigment dispersion to be used and the amount of the dispersion of the polymer particles.

(Comparative Examples 4 and 7)
In Comparative Example 4, an ink composition (R4) was prepared according to Example 8 of JP-A-2011-74377.
In Comparative Example 7, an ink composition (R7) was prepared according to Example 4 of JP-A-2011-57732.

Each component used is shown below.

(Pigment)

A dispersion was prepared in the same manner as in Example 1 using PY74: Irgalite Yellow GS (manufactured by BASF Japan Ltd.).

(Polymer particles)

The ratio of repeating units in the above (B1) to (B6) is a molar ratio.
(C1) · · · Hydran HW-350 (urethane resin), manufactured by DIC Corporation (C2) · · · Joncryl 537J (styrene-acrylic resin), manufactured by Johnson Polymer Corporation The above (C1) and (C2) are It is not a polymer particle containing a repeating unit having a hydrophilic group and a repeating unit having a cyclic aliphatic group.

The above (B6) was synthesized according to the description of [0334] of JP-A-2011-74377.

(Polymer dispersant)
(D1) and (D2) are as described above.

The ratio of repeating units in the above (D3) and (D4) is a molar ratio.
The above (D3) was synthesized according to the description of [Synthesis example 104] of JP-A-2011-74377.
The above (D4) was synthesized according to the description of [Synthesis example 2] of JP-A-2011-57732.

<Image recording and evaluation>
The following evaluation was performed using the ink composition of each Example and a comparative example as ink for inkjets. The results are shown in Table 3.
In Table 3, the light fastness, gloss, and scratch resistance were determined by loading each ink jet ink into an ink cartridge, and using an ink jet printer (Seiko Epson Co., Ltd .; PX-720A) with a stepwise yellow single color density. It evaluated using the printing matter which printed the image. As a recording medium, Fuji Photo Film Co., Ltd. picture painting photofinishing Pro was used.

-Stability over time-
The ink compositions (1) to (20) of Examples 1 to 20 and the ink compositions (R1) to (R7) of Comparative Examples 1 to 7 were allowed to stand at 70 ° C. for 14 days. The volume average particle size of pigment particles in the ink composition before standing at 70 ° C. for 14 days (also referred to as “before heating”) and after standing for 14 days at 70 ° C. (also referred to as “after heating”) The diameter and viscosity of the ink composition were measured. The particle size change rate and the viscosity change rate were calculated based on the following equation.
Particle size change rate (%) = (volume average particle size after heating / volume average particle size before heating) × 100
Viscosity change rate (%) = (viscosity after heating / viscosity before heating) x 100
Evaluation criteria were as follows.
A: Both the particle size change rate and the viscosity change rate fall within the range of 90 to 110% B: Either one of the particle size change rate or the viscosity change rate is less than 90% or more than 110% C: particle size Both change rate and viscosity change rate is less than 90% or more than 110%. The volume average particle size is TV-22 manufactured by Toki Sangyo Co., Ltd. using Nanotrac 150 (UPA-EX150) manufactured by Nikkiso Co., Ltd. The measurement was performed.

-Light resistance-
The OD (Optical Density) of the obtained image was measured with a reflection densitometer (GRETAG MACBETH Spectrolino), and a xenon weather meter (manufactured by Suga Test Instruments Co., Ltd.) for the image area with an OD of 0.5 ± 0.1 before irradiation. It irradiates under irradiance 50W / m ² (wavelength 300-400nm), # 320 filter conditions for 14 days using, and dye remaining rate [(post-irradiation density / pre-irradiation density) x 100%] is determined to obtain light resistance Was evaluated.
A: Dye residual ratio 90% or more B: Dye residual ratio less than 90% 80% or higher C: Dye residual ratio less than 80% 70% or higher D: Dye residual ratio less than 70%

-Glossy-
Among the obtained images, the 60 ° glossiness of the image area at a printing density of 100% was measured and evaluated using a gloss meter (IG-331 manufactured by Horiba, Ltd.). The printing density was measured with a reflection densitometer (GRETAG MACBETH Spectrolino).
A: 90 or more B: 70 or more and less than 90 C: 50 or more and less than 70 D: less than 50

-Scratch resistance-
Of the obtained images, the image area at a printing density of 100% was reciprocated 25 times by applying a 2N force with white cotton using a Gakushin-type friction tester (No. 428 manufactured by Yasuda Seiki Co., Ltd.) And after rubbing 50 times, the color transferred to the white cotton was visually evaluated. The printing density was measured with a reflection densitometer (GRETAG MACBETH Spectrolino).
A: No color transfer to white cotton is observed even after rubbing 50 times.
B: After 25 rubs, no color transfer to white cotton is observed, but after 50 rubs, slight transfer to white cotton is observed.
C: After 25 rubs, white cotton shows slight color transfer.
D: After 25 rubs, clear color transfer is observed on white cotton.

From the results shown in Table 3, it can be seen that the printed matter obtained from the ink composition of the example is excellent in light resistance.
By comparing Example 8, 13 to 17 etc. with Example 18, repeating units having a bicyclic or more polycyclic aliphatic hydrocarbon group (isobornyl (meth) acrylate, adamantyl (meth The use of a polymer particle containing a repeating unit derived from at least one selected from acrylate and dicyclopentanyl (meth) acrylate) shows excellent scratch resistance.
By comparing Example 1 with Examples 2 to 7, etc., it can be seen that the scratch resistance and the gloss are excellent when W _B / W _P is 1 or more.
By comparing Examples 2 and 19 etc. with Example 20, it is understood that the gloss is excellent by using the pigment represented by General Formula (1-1).
By comparing Examples 13 and 15, it can be seen that when the volume average particle size of the polymer particles is 1.4 nm or more, the temporal stability of the ink composition is excellent.
Further, by comparing Example 10 with Examples 2, 8 and 9, it is understood that the gloss is excellent when the volume average particle size of the polymer particles is 30 nm or less.
Furthermore, by comparing the difference between the results of Example and Comparative Example 1 with the difference between the results of Comparative Examples 5 and 6, a specific polymer dispersion can be obtained for the pigment represented by the specific formula (1) of the present invention. It can be seen that the light resistance is improved only when the agent and specific polymer particles are combined.

According to the present invention, it is possible to provide an ink composition and an image forming method which can provide a print having excellent light resistance.

Although the invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on Japanese Patent Application (Japanese Patent Application No. 2017-173362) filed on September 8, 2017, the contents of which are incorporated herein by reference.

Claims (8)

1. A pigment (P) represented by the following general formula (1), a polymer dispersant (D) containing a repeating unit having a hydrophilic group and a repeating unit having an aromatic group, a repeating unit having a hydrophilic group and a cyclic fat An ink composition comprising: polymer particles (B) comprising a repeating unit having a group group; and water.
   

   

   
   In general formula (1),
   Z represents a 5- or 6-membered heterocyclic ring which may have a substituent.
   Y ₁ , Y ₂ , R ₁₁ and R ₁₂ each independently represent a hydrogen atom or a substituent.
   G ₁ and G ₂ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted group It represents an aryl group or a substituted or unsubstituted heterocyclic group.
   W ₁ and W ₂ each independently represent a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.
2. The ink composition according to claim 1, wherein the cyclic aliphatic group contained in the polymer particle (B) is a polycyclic aliphatic hydrocarbon group.
3. The repeating unit having a cyclic aliphatic group contained in the polymer particle (B) is a repeating unit represented by the following general formula (b-1), a repeating unit represented by the following general formula (b-2), and The ink composition according to claim 1 or 2, which is at least one selected from the group consisting of repeating units represented by the following general formula (b-3).
   

   

   
   R _1b to R _3b in the general formulas (b-1) to (b-3) each independently represent a hydrogen atom or a methyl group.
4. The ink composition according to any one of claims 1 to 3, wherein the volume average particle diameter of the polymer particles (B) is 1.4 to 30 nm.
5. The ink composition according to any one of claims 1 to 4, wherein the pigment (P) is represented by the following general formula (1-1).
   

   

   
   In the general formula (1-1),
   R _1a , Y ₁ , Y ₂ , R ₁₁ and R ₁₂ each independently represent a hydrogen atom or a substituent.
   G ₁ and G ₂ each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aralkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted group It represents an aryl group or a substituted or unsubstituted heterocyclic group.
   W ₁ and W ₂ each independently represent a substituted or unsubstituted alkoxy group, a substituted or unsubstituted amino group, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.
6. 6. The method according to claim 1, wherein W _B / W _P, which is a ratio of the content W _P of the pigment (P) in the ink composition to the content W _B of the polymer particles (B), is 1 or more. The ink composition according to any one of the items.
   Where W _P is the ratio (mass%) of the mass of the pigment (P) to the total mass of the ink composition, and W _B is the ratio of the mass of the polymer particles (B) to the total mass of the ink composition (Mass%).
7. The ink composition according to any one of claims 1 to 6, which is for inkjet.
8. An image forming method comprising the step of applying the ink composition according to any one of claims 1 to 6 onto a recording medium by an inkjet method.