JP5301395B2 - Inkjet ink composition, inkjet recording method and printed matter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet ink composition having recording suitability (adhesion, bending resistance) for an unabsorbent base material such as a plastic, suppressing cockling, and being excellent in stability of the ink composition, delivering property (including delivery recovery after the stop of the delivery), and water resistance. <P>SOLUTION: This inkjet ink composition comprises (component A) an azo pigment represented by formula (1), (component B) at least one type of organic solvent represented by formula (2) or (3), and (component C) an organic solvent other than (component B). In the formulas, each symbol is specially defined. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a solvent-type inkjet ink composition, an inkjet recording method, and a printed matter.

The ink jet recording method is a recording method in which a liquid ink composition is ejected from a nozzle toward a recording medium using pressure, heat, an electric field or the like as a driving source. Such an ink jet recording method is rapidly spreading not only for office use but also for consumer use in recent years because of its low running cost and high image quality.
As an ink composition for inkjet recording, an aqueous dye ink obtained by dissolving a water-soluble dye in an aqueous medium is widely used for reasons such as excellent coloring power and less clogging at the head orifice.
On the other hand, in recent years, large-scale ink jet printers that can cope with A-0 size have been developed, and usage forms for outdoor applications such as outdoor posters are increasing. In addition, with the widespread use of digital cameras, applications that require long-term storage of printed materials are also increasing.

  Among pigment inks, aqueous pigment inks using water as a solvent have been widely used in recent years mainly for consumer inkjet printer applications from the viewpoint of safety and ease of handling. Among these, water-based pigment inks for ink jet recording include yellow pigments such as C.I. I. An azo pigment such as CI Pigment Yellow 74 is preferably used from the viewpoint of hue (see, for example, Patent Document 1). However, when water-based pigment ink is used, cockling (a phenomenon in which paper undulates) occurs when recording on plain paper. In addition, many recording media sold for water-based ink lack water resistance.

In contrast, when a solvent pigment ink using an organic solvent is used, recording can be performed without causing cockling even if plain paper, matte paper, etc. are used. A wide variety of recording media can be recorded. Furthermore, the solvent pigment ink using an organic solvent is superior in water resistance of the recorded matter as compared to the water-based ink.
In conventional solvent pigment inks, generally organic solvents such as aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons such as hexane and kerosene, ketones such as methyl ethyl ketone, esters such as ethyl acetate, or propylene glycol monomethyl Ether acetate etc. are used.

  Examples of solvent pigment inks include solvent-based pigment inks for jet printers using pigments and oleyl alcohol as a dispersion medium (see, for example, Patent Document 2), normal paraffins, isoparaffins or mixtures thereof as pigments and dispersion media. Ink-jet inks using a solvent as a solvent (see, for example, Patent Document 3) are disclosed, and carbonized as a main solvent for solvent pigment inks in aliphatic hydrocarbons or mixed solvents of aliphatic hydrocarbons and long-chain alcohols. The thing using what the molecular weight of hydrogen is large is disclosed.

JP 2000-239594 A JP 2000-38533 A JP 2001-329193 A

  However, when recording using the above-mentioned conventional solvent pigment ink using a commonly used organic solvent such as aliphatic hydrocarbons, ketones, esters, etc., it is possible to absorb a polyvinyl chloride substrate or the like as a recording medium. Use of a conductive substrate is not satisfactory in terms of image quality and dry handling of the image area. Conventional yellow pigments have poor dispersibility when dispersed and subsequent stability, making it difficult to obtain stable ink performance and ejection properties, and re-ejection properties (ejection recovery properties) after ejection, such as polyvinyl chloride. When recorded on a non-absorbable plastic substrate, the ink adhesion is poor.

  In the pigment inks of Patent Documents 2 to 3 using a solvent having a large hydrocarbon molecular weight as the main solvent of the solvent pigment ink, it is considered that the flash point is high and the danger is reduced, and cockling can be reduced to some extent. Insufficient adhesion of the ink makes ink rub easily.

  In general, when the boiling point or flash point of an organic solvent is low, the nozzle is easily clogged because drying is fast. In addition, the solvent should be selected so that it does not cost the printer specifications in terms of solubility and swelling in plastics (such as polystyrene resin and ABS resin) used in devices and parts such as ink storage containers and printers. Is desired. Therefore, even when an organic solvent is used as a solvent, solvent pigment ink using an organic solvent is useful as a recording material if the danger of ignition or handling such as installation of exhaust equipment is taken into consideration. is there.

  The problem to be solved by the present invention is based on the above circumstances, and has the ability to record on non-absorbent substrates such as plastics (adhesion and bending resistance) and suppress cockling. Another object of the present invention is to provide an ink-jet ink composition from which a printed matter excellent in stability, ejection property (including ejection recovery property after ejection stop) and water resistance of the ink composition can be obtained.

The above object of the present invention has been achieved by the following means.
<1> (Component A) An azo pigment represented by Formula (1), (Component B) at least one organic solvent represented by Formula (2) or Formula (3), and (Component C) (Component An ink-jet ink composition comprising an organic solvent other than B),

（式（１）中、Ｚは、５〜８員の含窒素ヘテロ環に由来する２価の基を表し、Ｙ₁、Ｙ₂、Ｒ₁₁及びＲ₁₂は、それぞれ独立に、水素原子又は１価の置換基を表し、Ｇ₁及びＧ₂は、それぞれ独立に、水素原子、アルキル基、アラルキル基、アルケニル基、アルキニル基、アリール基又はヘテロ環基を表し、Ｗ₁及びＷ₂は、それぞれ独立に、アルコキシ基、アミノ基、アルキル基又はアリール基を表す。）

(In the formula (1), Z represents a divalent group derived from a 5- to 8-membered nitrogen-containing heterocycle, and Y ₁ , Y ₂ , R ₁₁ and R ₁₂ are each independently a hydrogen atom or 1 Represents a valent substituent, G ₁ and G ₂ each independently represent a hydrogen atom, an alkyl group, an aralkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, and W ₁ and W ₂ each represent Independently represents an alkoxy group, an amino group, an alkyl group or an aryl group.)

（式（２）及び式（３）中、Ｒ₁、Ｒ₂及びＲ₄は、それぞれ独立に、−ＮＲ₆−又は酸素原子を表し、Ｒ₃、Ｒ₅は−Ｃ_mＨ_n−で表される炭化水素基を表し、分岐を有していてもよく、ｍは２〜８の整数を表し、ｎは（２ｍ−４）、（２ｍ−２）又は２ｍいずれかの整数を表し、Ｒ₆は炭素数１〜３のアルキル基、炭素数１〜３のヒドロキシアルキル基、ヒドロキシ基又は水素原子を表す。）

(In Formula (2) and Formula (3), R ₁ , R ₂ and R ₄ each independently represent —NR ₆ — or an oxygen atom, and R ₃ and R ₅ represent —C _m H _n —. Represents a hydrocarbon group which may be branched, m represents an integer of 2 to 8, n represents an integer of (2m-4), (2m-2) or 2m, R ₆ represents an alkyl group having 1 to 3 carbon atoms, a hydroxyalkyl group having 1 to 3 carbon atoms, a hydroxy group, or a hydrogen atom.

<2> The inkjet ink according to <1>, wherein W ₁ and W _{2 in} formula (1) are each independently an alkoxy group having 3 or less carbon atoms, an amino group, or an alkylamino group having 3 or less carbon atoms. Composition,
<3> The inkjet ink composition according to <1> or <2>, wherein G ₁ and G _{2 in} formula (1) are each independently an alkyl group having 3 or less carbon atoms,
<4> The inkjet ink composition according to any one of <1> to <3>, wherein Z in formula (1) is a divalent group derived from a 6-membered nitrogen-containing heterocycle,
<5> (Component B) is a carbonate compound, The inkjet ink composition as described in any one of <1>-<4>,
<6> The ink-jet ink composition according to any one of <1> to <5>, wherein (component B) is ethylene carbonate or propylene carbonate;
<7> (Component C) is a glycol ether, The inkjet ink composition according to any one of <1> to <6>,
<8> The inkjet ink composition according to any one of <1> to <7>, further comprising (Component D) a polymer dispersant and / or (Component E) a binder resin,
<9> A step of discharging the inkjet ink composition according to any one of <1> to <8> on a recording medium, and applying heat to the discharged inkjet ink composition, the inkjet ink A step of fixing the composition, and an inkjet recording method comprising:
<10> Printed matter recorded by the inkjet recording method according to <9>.

  According to the present invention, it has recording suitability (adhesion, bending resistance) to a non-absorbent substrate such as plastic, and cockling is suppressed, and the stability and ejection performance of the ink composition (after ejection is stopped). It is possible to provide an ink-jet ink composition from which a printed matter having excellent discharge resistance and water resistance can be obtained.

I. Inkjet ink composition The inkjet ink composition of the present invention comprises (component A) an azo pigment represented by formula (1), (component B) at least one organic compound represented by formula (2) or formula (3) It contains an organic solvent other than the solvent and (Component C) (Component B). The ink composition of the present invention is a “solvent ink jet ink composition” containing an organic solvent as an essential component.

（式（１）中、Ｚは、５〜８員の含窒素ヘテロ環に由来する２価の基を表し、Ｙ₁、Ｙ₂、Ｒ₁₁及びＲ₁₂は、それぞれ独立に、水素原子又は１価の置換基を表し、Ｇ₁及びＧ₂は、それぞれ独立に、水素原子、アルキル基、アラルキル基、アルケニル基、アルキニル基、アリール基又はヘテロ環基を表し、Ｗ₁及びＷ₂は、それぞれ独立に、アルコキシ基、アミノ基、アルキル基又はアリール基を表す。）

(In the formula (1), Z represents a divalent group derived from a 5- to 8-membered nitrogen-containing heterocycle, and Y ₁ , Y ₂ , R ₁₁ and R ₁₂ are each independently a hydrogen atom or 1 Represents a valent substituent, G ₁ and G ₂ each independently represent a hydrogen atom, an alkyl group, an aralkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, and W ₁ and W ₂ each represent Independently represents an alkoxy group, an amino group, an alkyl group or an aryl group.)

（式（２）及び式（３）中、Ｒ₁、Ｒ₂及びＲ₄は、それぞれ独立に、−ＮＲ₆−又は酸素原子を表し、Ｒ₃、Ｒ₅は−Ｃ_mＨ_n−で表される炭化水素基を表し、分岐を有していてもよく、ｍは２〜８の整数を表し、ｎは（２ｍ−４）、（２ｍ−２）又は２ｍいずれかの整数を表し、Ｒ₆は炭素数１〜３のアルキル基、炭素数１〜３のヒドロキシアルキル基、ヒドロキシ基又は水素原子を表す。）

(In Formula (2) and Formula (3), R ₁ , R ₂ and R ₄ each independently represent —NR ₆ — or an oxygen atom, and R ₃ and R ₅ represent —C _m H _n —. Represents a hydrocarbon group which may be branched, m represents an integer of 2 to 8, n represents an integer of (2m-4), (2m-2) or 2m, R ₆ represents an alkyl group having 1 to 3 carbon atoms, a hydroxyalkyl group having 1 to 3 carbon atoms, a hydroxy group, or a hydrogen atom.

Hereinafter, the inkjet ink composition of the present invention (hereinafter also simply referred to as “ink composition”) will be described in detail.
When the present inventors apply an azo pigment having a carbonyl group capable of forming an intramolecular hydrogen bond to a carbon atom adjacent to the carbon atom to which the azo group is bonded to the solvent-type inkjet ink composition, the ink composition The present invention has been completed by finding that it is excellent in ejection stability even after being stored for a long period of time or after being exposed to a high temperature, and as a result, the occurrence of density unevenness and stripe unevenness can be suppressed. Hereinafter, (Component A), (Component B), and (Component C) will be described in order.

(Component A) Azo Pigment Represented by Formula (1) The azo pigment used in the present invention can be typically represented by formula (1). In addition to the structure represented by the formula (1), the azo pigment of (Component A) may be a tautomer thereof, or a salt or hydrate thereof.
The compound represented by the formula (1) is likely to have an intermolecular interaction due to its specific chemical structure, and can be an azo pigment having low solubility in water or an organic solvent. Here, the pigment is used by being finely dispersed as solid particles forming a molecular aggregate in a solvent, unlike a dye used by being dissolved in water or an organic solvent in a molecular dispersion state.

（式（１）中、Ｚは、５〜８員の含窒素ヘテロ環に由来する２価の基を表し、Ｙ₁、Ｙ₂、Ｒ₁₁及びＲ₁₂は、それぞれ独立に、水素原子又は１価の置換基を表し、Ｇ₁及びＧ₂は、それぞれ独立に、水素原子、アルキル基、アラルキル基、アルケニル基、アルキニル基、アリール基又はヘテロ環基を表し、Ｗ₁及びＷ₂は、それぞれ独立に、アルコキシ基、アミノ基、アルキル基又はアリール基を表す。）

(In the formula (1), Z represents a divalent group derived from a 5- to 8-membered nitrogen-containing heterocycle, and Y ₁ , Y ₂ , R ₁₁ and R ₁₂ are each independently a hydrogen atom or 1 Represents a valent substituent, G ₁ and G ₂ each independently represent a hydrogen atom, an alkyl group, an aralkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, and W ₁ and W ₂ each represent Independently represents an alkoxy group, an amino group, an alkyl group or an aryl group.)

  In the formula (1), Z represents a divalent group derived from a 5- to 8-membered nitrogen-containing heterocycle, which may be further condensed. Preferred examples of the nitrogen-containing heterocycle include, but are not limited to, a pyrrole ring, a pyrazole ring, a triazole ring, an imidazole ring, a thiazole ring, an isothiazole ring, an oxazole ring, an isoxazole ring, a thiadiazole ring, a thiophene ring, Examples include a furan ring, a pyridine ring, a pyrimidine ring, a triazine ring, a pyridazine ring, and a pyrazine ring. More preferably, it is a 6-membered nitrogen-containing heterocycle, and examples thereof include a pyridine ring, a pyrimidine ring, and an S-triazine ring. Z is particularly preferably a divalent group derived from a pyrimidine ring. The fact that Z is a divalent group derived from a 6-membered nitrogen-containing heterocycle is that the intramolecular and intermolecular interactions of the dye molecule are easy to improve in terms of hydrogen bonding and molecular planarity. preferable.

In Formula (1), Y ₁ and Y ₂ each independently represent a hydrogen atom or a monovalent substituent. Monovalent substituents include halogen atoms, alkyl groups (straight chain, branched, cyclic substituted or unsubstituted alkyl groups, including cycloalkyl groups, bicycloalkyl groups, and tricyclo structures with many ring structures. An alkyl group (for example, an alkoxy group, an alkylcarbonyl group, or an alkyl group in an alkylsulfonyl group) in the substituents described below also represents such an alkyl group, an aralkyl group, and an alkenyl group. Group, alkynyl group, aryl group, heterocyclic group, cyano group, hydroxy group, nitro group, alkoxy group, aryloxy group, silyloxy group, heterocyclic oxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group, aryloxy Carbonyloxy group, amino group, acylamino group, aminocarboni Amino 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, aryloxycarbonyl group, alkoxycarbonyl group, carbamoyl group, aryl or heterocyclic azo group, imide group, phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, silyl Groups.

Y ₁ and Y ₂ are preferably a hydrogen atom, an alkyl group (for example, a methyl group), an aryl group (for example, a phenyl group), a heterocyclic group (for example, a 2-pyridyl group), an alkylthio group (for example, a methylthio group). More preferably, they are a hydrogen atom, a methyl group, a phenyl group, and a methylthio group, and particularly preferably a hydrogen atom. Y ₁ and Y ₂ may be the same or different.

In the formula (1), R ₁₁ and R ₁₂ each independently represent a hydrogen atom or a monovalent substituent. When R ₁₁ and R ₁₂ represent a monovalent substituent, examples thereof include a linear or branched alkyl group having 1 to 12 carbon atoms (for example, methyl, ethyl, n-propyl, i-propyl, n -Butyl, i-butyl, sec-butyl, t-butyl, 2-ethylhexyl, 2-methylsulfonylethyl, 3-phenoxypropyl, trifluoromethyl), a linear or branched aralkyl group having 7 to 18 carbon atoms (for example, Benzyl), a linear or branched alkenyl group having 2 to 12 carbon atoms (for example, vinyl), a linear or branched alkynyl group having 2 to 12 carbon atoms (for example, ethynyl), a linear chain having 3 to 12 carbon atoms Or a branched chain cycloalkyl group (for example, cyclopentyl), a linear or branched cycloalkenyl group having 3 to 12 carbon atoms (for example, cyclopentenyl), a halogen atom (for example, a chlorine atom) , Bromine atom), aryl group (eg, phenyl, 4-t-butylphenyl, 2,4-di-t-amylphenyl), heterocyclic group (eg, imidazolyl, pyrazolyl, triazolyl, 2-furyl, 2-thienyl) 2-pyrimidinyl, 2-benzothiazolyl), cyano group, hydroxy group, nitro group, carboxy group, amino group, alkyloxy group (for example, methoxy, ethoxy, 2-methoxyethoxy, 2-methylsulfonylethoxy), aryloxy group (For example, phenoxy, 2-methylphenoxy, 4-t-butylphenoxy, 3-nitrophenoxy, 3-t-butyloxycarbonylphenoxy, 3-methoxycarbonylphenyloxy, acylamino groups (for example, acetamide, benzamide, 4- ( 3-t-butyl-4-hydroxy Enoxy) butanamide), alkylamino groups (eg methylamino, butylamino, diethylamino, methylbutylamino), arylamino groups (eg phenylamino, 2-chloroanilino), ureido groups (eg phenylureido, methylureido, N , N-dibutylureido), sulfamoylamino group (for example, N, N-dipropylsulfamoylamino), alkylthio group (for example, methylthio, octylthio, 2-phenoxyethylthio), arylthio group (for example, phenylthio, 2 -Butoxy-5-t-octylphenylthio, 2-carboxyphenylthio), alkyloxycarbonylamino groups (eg methoxycarbonylamino), alkylsulfonylamino groups and arylsulfonylamino groups (eg Acetylsulfonylamino, phenylsulfonylamino, p-toluenesulfonylamino), carbamoyl group (eg, N-ethylcarbamoyl, N, N-dibutylcarbamoyl), sulfamoyl group (eg, N-ethylsulfamoyl, N, N-dipro) Pyrsulfamoyl, N-phenylsulfamoyl), sulfonyl group (eg, methylsulfonyl, octylsulfonyl, phenylsulfonyl, p-toluenesulfonyl), alkyloxycarbonyl group (eg, methoxycarbonyl, butyloxycarbonyl), heterocyclic oxy Groups (for example, 1-phenyltetrazol-5-oxy, 2-tetrahydropyranyloxy), azo groups (for example, phenylazo, 4-methoxyphenylazo, 4-pivaloylaminophenylazo, 2-hydroxy 4-propanoylphenylazo), acyloxy group (for example, acetoxy), carbamoyloxy group (for example, N-methylcarbamoyloxy, N-phenylcarbamoyloxy), silyloxy group (for example, trimethylsilyloxy, dibutylmethylsilyloxy), aryl Oxycarbonylamino group (for example, phenoxycarbonylamino), imide group (for example, N-succinimide, N-phthalimide), heterocyclic thio group (for example, 2-benzothiazolylthio, 2,4-di-phenoxy-1, 3,5-triazole-6-thio, 2-pyridylthio), sulfinyl group (eg 3-phenoxypropylsulfinyl), phosphonyl group (eg phenoxyphosphonyl, octyloxyphosphonyl, phenylphosphonyl), aryl Examples include a xycarbonyl group (for example, phenoxycarbonyl), an acyl group (for example, acetyl, 3-phenylpropanoyl, benzoyl), and an ionic hydrophilic group (for example, a carboxy group, a sulfo group, a phosphono group, and a quaternary ammonium group). It is done.

In formula (1), preferred R ₁₁ and R ₁₂ are a substituted or unsubstituted acylamino group having 1 to 8 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted carbon number 6 Is an aryl group of ˜18 or a substituted or unsubstituted heterocyclic group having 4 to 12 carbon atoms, more preferably a linear alkyl group having 1 to 8 carbon atoms or a branched alkyl group, and further preferably a methyl group or isopropyl. Group or t-butyl group, and among them, t-butyl group is particularly preferable. R ₁₁ and R ₁₂ may be the same or different.

G ₁ and G ₂ in Formula (1) represent a hydrogen atom, an alkyl group, a cycloalkyl group, an aralkyl group, an alkenyl group, an alkynyl group, an aryl group, or a heterocyclic group, preferably a hydrogen atom, a methyl group, or an ethyl group Group, n-propyl group, isopropyl group, t-butyl group, cyclopropyl group, benzyl group, 2-phenethyl group, vinyl group, allyl group, ethynyl group, propargyl group, phenyl group, p-tolyl group, naphthyl group, A pyridyl group, a pyrimidinyl group, and a pyrazinyl group, more preferably a hydrogen atom, a methyl group, a phenyl group, a pyridyl group, a pyrimidinyl group, and a pyrazinyl group. Among them, a methyl group, a 2-pyridyl group, 2,6- A pyrimidinyl group or a 2,5-pyrazinyl group is particularly preferred.
Further, when G ₁ and G ₂ represents an alkyl group, preferably an alkyl group having 5 or less carbon atoms, more preferably an alkyl group having 3 or less carbon atoms, most preferably a methyl group. G ₁ and G ₂ may be the same or different.

In Formula (1), W ₁ and W ₂ each independently represent an alkoxy group, an amino group, an alkyl group, or an aryl group. Examples of the alkoxy group represented by W ₁ and W ₂ include substituted or unsubstituted alkoxy groups having 1 to 30 carbon atoms, such as a methoxy group, an ethoxy group, an isopropoxy group, a t-butoxy group, and an n-hexyloxy group. , N-octyloxy group, 2-methoxyethoxy group and the like are preferable.

Examples of the amino group represented by W ₁ and W ₂ include an amino group, an alkylamino group, a dialkylamino group, an arylamino group, a diarylamino group, and a heterocyclic amino group. 30 substituted or unsubstituted alkylamino groups, 1 to 30 carbon atoms substituted or unsubstituted dialkylamino groups, 6 to 30 carbon atoms substituted or unsubstituted anilino groups such as methylamino group, dimethylamino group, Anilino group, N-methyl-anilino group, diphenylamino group and the like can be mentioned.

Examples of the alkyl group represented by W ₁ and W ₂ include a linear, branched, and cyclic substituted or unsubstituted alkyl group. The alkyl group has a cycloalkyl group, a bicycloalkyl group, and more ring structures. A tricyclo structure and the like are also included.
Specifically, the alkyl group is preferably an alkyl group having 1 to 30 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, a t-butyl group, an n-octyl group, an eicosyl group, Examples include 2-chloroethyl group, 2-cyanoethyl group, 2-ethylhexyl group and the like. Preferred examples of the cycloalkyl group include substituted or unsubstituted cycloalkyl groups having 3 to 30 carbon atoms such as a cyclohexyl group, a cyclopentyl group, and a 4-n-dodecylcyclohexyl group. The bicycloalkyl group is preferably a substituted or unsubstituted bicycloalkyl group having 5 to 30 carbon atoms, that is, a monovalent group obtained by removing one hydrogen atom from a bicycloalkane having 5 to 30 carbon atoms, for example, bicyclo [ 1.2.2] heptan-2-yl group, bicyclo [2.2.2] octane-3-yl group and the like.

The aryl group represented by W ₁ and W ₂ is preferably a substituted or unsubstituted aryl group having 6 to 30 carbon atoms such as a phenyl group, a p-tolyl group, a naphthyl group, an m-chlorophenyl group, o -Hexadecanoylaminophenyl group etc. are mentioned.

Among them, preferred W ₁ and W ₂ are an alkoxy group, an amino group, an alkylamino group, a dialkylamino group or an alkyl group, more preferably an alkoxy group, an amino group, an alkylamino group, or a dialkylamino group, and even more preferred. Is an alkoxy group having 5 or less carbon atoms, an amino group (—NH ₂ group), an alkylamino group having 5 or less carbon atoms, or a dialkylamino group having 10 or less carbon atoms, particularly preferably an alkoxy group having 3 or less carbon atoms, It is an alkylamino group having 3 or less carbon atoms or a dialkylamino group having 6 or less carbon atoms, and among them, a methoxy group is most preferable.
When W ₁ and W ₂ are an alkoxy group having 5 or less carbon atoms, an amino group, or an alkylamino group having 5 or less carbon atoms, the dye molecule can easily form a strong interaction between molecules and between molecules, and is more stable. It is preferable from the viewpoint of good hue and high fastness (light resistance, gas, heat, water, chemicals). W ₁ and W ₂ may be the same or different.

In the present invention, when Z, Y ₁ , Y ₂ , R ₁₁ , R ₁₂ , G ₁ , G ₂ , W ₁ and W ₂ are groups that can further have a substituent, The following substituents can be mentioned.

  Examples of the substituent include a halogen atom, alkyl group, aralkyl group, alkenyl group, alkynyl group, aryl group, heterocyclic group, cyano group, hydroxy group, nitro group, alkoxy group, aryloxy group, silyloxy group, and heterocyclic ring. 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, aryl Alkoxycarbonyl 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, and a silyl group.

  The azo pigment in the present invention includes in its scope the tautomer of the azo pigment represented by the formula (1). Formula (1) is shown in the form of an extreme structural formula among several tautomers that can be taken in terms of chemical structure, but may be a tautomer other than the described structure, You may use as a mixture containing the tautomer. For example, for the azo pigment represented by the formula (1), an azo-hydrazone tautomer represented by the formula (1 ′) can be considered. The present invention includes in its scope a compound represented by the following formula (1 ') which is a tautomer of the azo pigment represented by the formula (1).

In 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 , W in formula (1). ₂ , Y ₁ , Y ₂ , G ₁ , G ₂ and Z have the same meanings.

  In addition, about the preferable combination of a substituent of the compound represented by said Formula (1), the compound whose at least 1 of various substituents is the said preferable group is preferable, and more various substituents are the said preferable group. Are more preferred, and compounds in which all substituents are the preferred groups are most preferred.

A particularly preferred combination as the azo pigment represented by the formula (1) of the present invention includes the following (A) to (E).
(A) W ₁ and W ₂ are each independently an alkoxy group (for example, methoxy group, ethoxy group, isopropoxy group, t-butoxy group), amino group (for example, —NH ₂ group, methylamino group, dimethyl group). Amino group, anilino group), alkyl group (for example, methyl group, ethyl group, n-propyl group, isopropyl group, t-butyl group, cyclopropyl group) or aryl group (for example, phenyl group, p-tolyl group, naphthyl) Group), preferably an alkoxy group, an amino group or an alkyl group, more preferably an alkoxy group or an amino group, still more preferably an alkoxy group having 5 or less carbon atoms, an amino group (—NH ₂ group). , an alkyl amino group having 5 or less carbon atoms, particularly preferably having 3 or less of the alkoxy group having a carbon, an amino group (-NH ₂ group), of 3 or less carbon atoms An alkylamino group, especially a methoxy group (-OCH ₃ group) is the most preferred among them.

(B) R ₁₁ and R ₁₂ are each independently a hydrogen atom or a substituent (for example, a substituted or unsubstituted acylamino group having 1 to 8 carbon atoms, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, A substituted or unsubstituted aryl group having 6 to 18 carbon atoms or a substituted or unsubstituted heterocyclic group having 4 to 12 carbon atoms) is preferable, and a linear alkyl group or branched alkyl group having 1 to 8 carbon atoms is more preferable, A methyl group, an isopropyl group or a tert-butyl group is more preferable. Of these, a tert-butyl group is most preferred.

  (C) Z represents a divalent group derived from a 5- to 8-membered nitrogen-containing heterocyclic group, and they may be further condensed. As the nitrogen-containing heterocycle in Z, a 5- or 6-membered substituted or unsubstituted nitrogen-containing heterocycle such as a pyrrole ring, pyrazole ring, triazole ring, imidazole ring, thiazole ring, isothiazole ring, oxazole ring, isoxazole Ring, thiadiazole ring, thiophene ring, furan ring, pyridine ring, pyrimidine ring, triazine ring and pyridazine ring are preferable, a 6-membered nitrogen-containing heterocyclic group having 3 to 10 carbon atoms is more preferable, pyridine ring, pyrimidine ring, S- A triazine ring, a pyridazine ring and a pyrazine ring are more preferable, and a pyrimidine ring and an S-triazine ring are particularly preferable. Of these, the pyrimidine ring is most preferable.

(D) G ₁ and G ₂ each independently represent a hydrogen atom, an alkyl group, a cycloalkyl group, an aralkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, among which a hydrogen atom, a methyl group, Ethyl group, n-propyl group, isopropyl group, t-butyl group, cyclopropyl group, benzyl group, 2-phenethyl group, vinyl group, allyl group, ethynyl group, propargyl group, phenyl group, p-tolyl group, naphthyl group , A pyridyl group, a pyrimidinyl group and a pyrazinyl group are preferable, and a hydrogen atom, a methyl group, a phenyl group, a pyridyl group, a pyrimidinyl group and a pyrazinyl group are more preferable. Among these, a methyl group, 2-pyridyl group, 2,6-pyrimidinyl group, and 2,5-pyrazinyl group are more preferable. The alkyl group represented by G ₁ or G ₂ is more preferably an alkyl group having 5 or less carbon atoms, more preferably an alkyl group having 3 or less carbon atoms, and most preferably a methyl group.

(E) Y ₁ and Y ₂ each independently represent a hydrogen atom, an alkyl group (for example, a methyl group), an aryl group (for example, a phenyl group), a heterocyclic group (for example, a 2-pyridyl group), or an alkylthio group (for example, , A methylthio group), and more preferably a hydrogen atom, a methyl group, a phenyl group, or a methylthio group. Among these, a hydrogen atom is the most preferable.

  Of the azo pigments represented by the above formula (1) in the present invention, an azo pigment represented by the formula (1-2) is preferable.

G ₁ , G ₂ , R ₁₁ , R ₁₂ , W ₁ , W ₂ , Y ₁ and Y ₂ in the above formula (1-2) are the same as G ₁ , G ₂ , R ₁₁ , R ₁₂ , W ₁ , W ₂ , Y ₁ and Y ₂ have the same meanings. Moreover, the dotted bond in Formula (1-2) represents a place where a hydrogen bond is possible.
X ₁₁ and X ₁₂ each independently represent a hetero atom in a divalent group (Het.) Derived from the nitrogen-containing heterocyclic compound represented by Z in the formula (1).

In the present invention, a large number of tautomers can be considered in the azo pigment represented by the above formula (1).
In the present invention, the azo pigment represented by the formula (1) preferably has a substituent that forms an intramolecular hydrogen bond or an intramolecular cross-hydrogen bond. The azo pigment represented by the formula (1) in the present invention preferably has at least one or more substituents that form an intramolecular cross-hydrogen bond, and at least three or more substituents that form an intramolecular hydrogen bond. It is more preferable that it has a substituent that forms at least three intramolecular hydrogen bonds, and at least two of the hydrogen bonds have a substituent that forms an intramolecular cross-hydrogen bond. Particularly preferred.

Among the azo pigments represented by the formula (1), as described above, examples of the particularly preferable azo pigments include azo pigments represented by the above formula (1-2). As a preferable factor for this structure, as shown in formula (1-2), a nitrogen atom, a hydrogen atom, and a heteroatom (a hydrazone group that is an azo group or a tautomer thereof) constituting a heterocycle contained in an azo pigment structure And the nitrogen atom of the carbonyl group or the nitrogen atom of the amino group) easily form at least one intramolecular hydrogen bond (intramolecular hydrogen bond).
As preferred factors for these structures, as shown in the above formula (1-2), a nitrogen atom, a hydrogen atom of an amino group, and a hetero atom (for example, an azo group or its group) A tautomer hydrazone group nitrogen atom, carbonyl group oxygen atom or amino group nitrogen atom) can easily form at least four intramolecular hydrogen bonds, and at least two intramolecular It is easy to form cross hydrogen bonds. As a result, the planarity of the molecule is improved, the intramolecular / intermolecular interaction is further improved, and for example, the crystallinity of the azo pigment represented by the formula (1-2) is increased (higher-order structure is easily formed). ), The required performance as a pigment, which is the most preferred example, since the light fastness, thermal stability, wet heat stability, water resistance, gas resistance and / or solvent resistance are greatly improved.
Moreover, in the azo pigment in this invention, the compound represented by Formula (1) may contain isotopes (for example, ² H, ³ H, ¹³ C, ¹⁵ N).

  Hereinafter, as specific examples of the azo pigment represented by the formula (1), Pig. -1 to Pig. Although -46 is shown, the azo pigment used in the present invention is not limited to the following examples. In addition, the structures of the following specific examples are shown in the form of an ultimate structural formula among several tautomers that can be taken in terms of chemical structure. Needless to say, it may be.

  In the present invention, as (Component A), Pig. -1 or Pig. -18 can be preferably used.

  The azo pigment represented by the formula (1) in the present invention may be one having a chemical structural formula represented by the formula (1) or a tautomer thereof, and the crystal form is not particularly limited. For example, the pigment may be any crystal form called polymorph (crystal polymorph).

Crystal polymorphs refer to crystals that have the same chemical composition but differ in the arrangement of building blocks (molecules or ions) in the crystal. In crystal polymorphs, the crystal structure determines the chemical and physical properties, and each crystal polymorph can be distinguished by its rheology, hue and other color characteristics. Different crystal polymorphs can also be confirmed by X-Ray Diffraction (powder X-ray diffraction measurement result) or X-Ray Analysis (X-ray crystal structure analysis result).
When a crystalline polymorph exists in the azo pigment represented by the formula (1) in the present invention, the crystalline form may be any polymorph, or a mixture of two or more polymorphs. The main component is preferably a single crystal type. That is, it is preferable that the polymorph is less mixed, and the content of the azo pigment having a single crystal type is 70% to 100%, preferably 80% to 100%, more preferably 90% to the entire azo pigment. 100%, more preferably 95% to 100, particularly preferably 100%.

By using an azo pigment having a single crystal form as a main component, the regularity of the dye molecule arrangement is improved, the intramolecular / intermolecular interaction is strengthened, and a higher-order three-dimensional network is easily formed. . As a result, it is preferable in terms of performance required for pigments such as improvement of hue, light fastness, heat fastness, humidity fastness, oxidizing gas fastness and solvent resistance.
The mixing ratio of crystal polymorphs in azo pigments is based on solid physicochemical measurements such as single crystal X-ray crystal structure analysis, powder X-ray diffraction (XRD), crystal micrograph (TEM), IR (KBr method), etc. I can confirm.

  In the present invention, when the azo pigment represented by the formula (1) has an acid group, a part or all of the acid group may be a salt type, and a salt type pigment and a free acid type A pigment may be mixed. Examples of the salt type include salts of alkali metals such as Na, Li and K, ammonium salts which may be substituted with alkyl groups or hydroxyalkyl groups, and organic amine salts. Examples of organic amines include lower alkyl amines, hydroxy-substituted lower alkyl amines, carboxy-substituted lower alkyl amines, 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.

  Further, in the structure of the azo pigment used in the present invention, when a plurality of acid groups are contained in one molecule, the plurality of acid groups are each independently a salt type or an acid type and are different from each other. May be.

  In the present invention, the azo pigment represented by the formula (1) may be a hydrate containing water molecules in the crystal, and the number of water molecules contained in the crystal is not particularly limited.

Next, an example of a method for producing the azo pigment represented by the above formula (1) will be described.
The azo pigment represented by the formula (1) is obtained by, for example, diazoniumizing a heterocyclic amine represented by the formula (A) under acidic conditions, and performing a coupling reaction with the compound represented by the formula (B). It can manufacture by performing the post-processing by.

In the formulas (A) and (B), W has the same meaning as W ₁ and W ₂ in the formula (1), G has the same meaning as G ₁ and G ₂ in the formula (1), R ₁₁ , R ₁₂ and Z has the same meaning as R ₁₁ , R ₁₂ and Z in formula (1).

  The heterocyclic amine represented by the above formula (A) is generally a known and commonly used method, for example, Helv. Chim. Acta, 41, 1958, 1052 to 1056 and Helv. Chim. Acta, 42, 1959, 349 to 352 and the like, and the like. Moreover, the compound represented by the said Formula (B) can be manufactured by the method as described in the international publication 06/082669 pamphlet and Unexamined-Japanese-Patent No. 2006-57076, and the method according to it.

The diazoniumation reaction of the heterocyclic amine represented by the above formula (A) can be carried out, for example, in an acidic solvent such as sulfuric acid, phosphoric acid, acetic acid, hydrochloric acid, methanesulfonic acid, sodium nitrite, nitrosyl sulfuric acid, isoamyl nitrite and the like. The reaction can be carried out by reacting the reagent at a temperature of 15 ° C. or lower for about 10 minutes to 6 hours.
In the coupling reaction, the diazonium salt obtained by the above method and the compound represented by the above formula (B) are preferably reacted at 40 ° C. or lower, more preferably at 25 ° C. or lower for 10 minutes to 12 hours. Can be done.

  Crystals may be precipitated in the case of reaction in this way, but in general, water or an alcohol solvent is added to the reaction solution to precipitate crystals, and the crystals are collected by filtration. Can do. In addition, an alcohol solvent, water or the like can be added to the reaction solution to precipitate crystals, and the precipitated crystals can be collected by filtration. The crystal collected by filtration can be washed and dried as necessary to obtain an azo pigment represented by the formula (1).

The azo pigment represented by the above formula (1) is obtained as a crude azo pigment (crude) by the above production method, but when used as a pigment in the inkjet ink composition of the present invention, the crude azo pigment (crude) It is preferable to carry out post-processing on the surface.
Examples of post-treatment methods include solvent salt milling, salt milling, dry milling, solvent milling, pigment particle control step by grinding treatment such as acid pasting, solvent heating treatment, resin, surfactant and dispersant. The surface treatment process by etc. is mentioned.

The azo pigment represented by the formula (1) is preferably subjected to solvent heat treatment and / or solvent salt milling as a post-treatment.
Examples of the solvent used in the solvent heat treatment include water, aromatic hydrocarbon solvents such as toluene and xylene, halogenated hydrocarbon solvents such as chlorobenzene and o-dichlorobenzene, and alcohols such as isopropanol and isobutanol. Examples thereof include solvents, polar aprotic organic solvents such as N, N-dimethylformamide, N, N-dimethylacetamide, and N-methyl-2-pyrrolidone, glacial acetic acid, pyridine, and mixtures thereof. An inorganic or organic acid or base may be further added to the solvents mentioned above. The temperature of the solvent heat treatment varies depending on the desired primary particle size of the pigment, but is preferably 40 to 150 ° C, more preferably 60 to 100 ° C. The treatment time is preferably 30 minutes to 24 hours.

  As solvent salt milling, for example, a crude azo pigment, an inorganic salt, and an organic solvent that does not dissolve the crude azo pigment are charged into a kneader and kneaded and ground therein. As said inorganic salt, water-soluble inorganic salt can be used conveniently, For example, it is preferable to use inorganic salts, such as sodium chloride, potassium chloride, sodium sulfate. Moreover, it is more preferable to use an inorganic salt having an average particle size of 0.5 to 50 μm. The amount of the inorganic salt used is preferably 3 to 20 times by weight, more preferably 5 to 15 times by weight with respect to the crude azo pigment. As the organic solvent, a water-soluble organic solvent can be suitably used, but a high boiling point solvent is preferable from the viewpoint of safety because the solvent easily evaporates due to a temperature rise during kneading.

  Examples of such organic solvents include diethylene glycol, glycerin, ethylene glycol, propylene glycol, liquid polyethylene glycol, liquid polypropylene glycol, 2- (methoxymethoxy) ethanol, 2-butoxyethanol, 2- (isopentyloxy) ethanol. 2- (hexyloxy) ethanol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol, triethylene glycol monomethyl ether, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, Dipropylene glycol, dipropylene glycol monomethyl ether, dipropylene glycol monomethyl ether, dipro Glycol or mixtures thereof. The amount of the water-soluble organic solvent used is preferably 0.1 to 5 times by weight with respect to the crude azo pigment. The kneading temperature is preferably 20 to 130 ° C, particularly preferably 40 to 110 ° C. As a kneader, for example, a kneader or a mix muller can be used.

  In the present invention, the average particle diameter of the azo pigment particles represented by the formula (1) is preferably 0.005 to 0.5 μm, more preferably 0.01 to 0.45 μm, still more preferably 0.015 to 0. It is preferable to set the pigment, the dispersant, the medium, the dispersion conditions, and the filtration conditions so that the thickness is 4 μm.

  The ink composition of the present invention only needs to contain at least one of the azo pigment represented by the formula (1) and tautomers thereof, and salts and hydrates thereof. May be used in combination. Further, the content of the azo pigment represented by the formula (1) and its tautomers and salts and hydrates thereof is preferably 0.1 to 10% by weight with respect to the total amount of the ink composition, 1-7 weight% is more preferable, and 2-5 weight% is further more preferable. When the content of the azo pigment represented by the formula (1) is within this range, a desired yellow hue can be obtained and the ejection stability is excellent.

In addition to the azo pigment represented by the formula (1), the following pigment can be used in combination with the ink composition of the present invention. Examples of pigments that can be used in combination include C.I. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 14C, 16, 17, 24, 34, 35, 37, 42, 53, 55, 65, 73, 74, 75, 81, 83, 93, 95, 97, 98, 100, 101, 104, 108, 109, 110, 114, 117, 120, 128, 129, 138, 150, 151, 153, 154, 155, 180.
Thus, when using together the azo pigment represented by Formula (1) and other pigments, the content of the azo pigment represented by Formula (1) is preferably 20% by weight or more based on the total pigment, 30 weight% or more is more preferable.

(Component B) At least one organic solvent represented by formula (2) or formula (3) The ink composition of the present invention comprises at least one organic solvent represented by formula (2) or formula (3). Containing.

（式（２）及び式（３）中、Ｒ₁、Ｒ₂及びＲ₄は、それぞれ独立に、−ＮＲ₆−又は酸素原子を表し、Ｒ₃、Ｒ₅は−Ｃ_mＨ_n−で表される炭化水素基を表し、分岐を有していてもよく、ｍは２〜８の整数を表し、ｎは（２ｍ−４）、（２ｍ−２）又は２ｍいずれかの整数を表し、Ｒ₆は炭素数１〜３のアルキル基、炭素数１〜３のヒドロキシアルキル基、ヒドロキシ基又は水素原子を表す。）

(In Formula (2) and Formula (3), R ₁ , R ₂ and R ₄ each independently represent —NR ₆ — or an oxygen atom, and R ₃ and R ₅ represent —C _m H _n —. Represents a hydrocarbon group which may be branched, m represents an integer of 2 to 8, n represents an integer of (2m-4), (2m-2) or 2m, R ₆ represents an alkyl group having 1 to 3 carbon atoms, a hydroxyalkyl group having 1 to 3 carbon atoms, a hydroxy group, or a hydrogen atom.

In Formula (2), R ₁ and R ₂ each independently represent —NR ₆ — or an oxygen atom, and R ₆ represents an alkyl group having 1 to 3 carbon atoms, a hydroxyalkyl group having 1 to 3 carbon atoms, or a hydroxy group. Or represents a hydrogen atom. R ₆ is preferably an alkyl group having 1 to 3 carbon atoms, a hydroxyalkyl group having 1 to 3 carbon atoms, or a hydrogen atom, and more preferably an alkyl group having 1 to 3 carbon atoms or a hydrogen atom. At least one of R ₁ and R ₂ is preferably an oxygen atom, and both are oxygen atoms, that is, the organic solvent represented by the formula (2) is more preferably a carbonate compound.
In formula (2), R ₃ represents a hydrocarbon group represented by —C _m H _n —, which may have a branch, m represents an integer of 2 to 8, and n represents (2m−4 ), An integer of (2m-2) or 2m. M in R ³ is preferably an integer of 2 to 6, more preferably an integer of 2 to 4, and further preferably 2 or 3. N in R ³ is preferably (2m−2) or 2m, and more preferably 2m.
Specific examples of R ₃ are preferably an ethylene group, a 1-methylethylene group, and a propylene group. Of these, an ethylene group or a 1-methylethylene group is particularly preferable.

In formula (3), R ₄ represents —NR ₆ — or an oxygen atom, and more preferably —NR ₆ —. R ₆ is preferably an alkyl group having 1 to 3 carbon atoms, a hydroxyalkyl group having 1 to 3 carbon atoms, or a hydrogen atom, and more preferably an alkyl group having 1 to 3 carbon atoms or a hydrogen atom.
In formula (3), R ₅ is -C _m H _n - represents a hydrocarbon group represented by may be branched, m represents an integer of 2 to 8, n is (2m-4 ), An integer of (2m-2) or 2m. M in R ₅ is preferably an integer of 2 to 6, more preferably an integer of 2 to 4, and further preferably 2 or 3. N in R ₅ is preferably (2m−2) or 2m, and more preferably 2m.

In the present invention, the organic solvent represented by the formula (2) can be used more preferably than the organic solvent represented by the formula (3).
The ink composition of the present invention preferably contains at least an organic solvent represented by the formula (2), and more preferably contains at least a carbonate compound represented by the formula (2).

  The inkjet ink composition of the present invention contains at least one cyclic urea compound or oxazolidinone compound (for example, 3-methyl-2-oxazolidinone, 3-ethyl-2-oxazolidinone, 3-propyl-2-oxazolidinone, etc.) as an organic solvent. ), Preferably a cyclic carbonate compound, more preferably a cyclic carbonate compound, and particularly preferably ethylene carbonate or propylene carbonate. By using these organic solvents as a main component, an ink composition containing a solvent having a lower molecular weight and a higher boiling point than cyclic lactones and glycols can be produced.

  The organic solvent used in the ink composition is desired to have a high boiling point in the environment, but a low molecular weight compound having excellent permeability is desirable in consideration of fixing properties. On the other hand, by reducing the amount of water and using a high-boiling solvent as a main component, it is possible to increase the affinity for a recording medium that is more hydrophobic as compared with an ink containing water as a main component. The paper medium includes various recording media from paper made suitable for ink mainly composed of oil such as offset ink to medium dedicated to water-based ink for ink jet recording. When water-based ink is printed on paper used for offset printing, the ink is repelled and unevenness occurs. On the other hand, when the solvent has a high molecular weight and a high boiling point, the penetration into paper becomes slow, resulting in poor fixability.

(Component C) Organic solvent other than (Component B) The inkjet ink composition of the present invention contains at least one organic solvent other than (Component B). Examples of organic solvents other than (Component B) include solvents such as alcohol compounds, ketone compounds, ester compounds, amine compounds, glycol compounds, glycol ether compounds, aromatic compounds, and hydrocarbon compounds. A solvent etc. can be mentioned.

As the organic solvent preferable as (Component C), the volatilization suppression of the solvent-type ink in the equipment such as the nozzle part and the tube, the prevention of solidification, and the excellent re-solubility when solidified, the suppression of cockling of plain paper. In this respect, glycol ethers are preferable, and monoalkyl ether or dialkyl ether of either polyoxyethylene glycol or polyoxypropylene glycol is more preferable. Specifically, an organic solvent represented by the following formula (α), formula (β) or formula (γ) is preferable.
As the organic solvent, polyoxyethylene glycol dialkyl ether represented by the formula (α) is preferable.
R ²¹ — (OC ₂ H ₄ ) _n —OR ²² (α)

In the formula (α), R ²¹ and R ²² each independently represents an alkyl group having 1 to 3 carbon atoms. n represents an integer of 2 to 4, and is preferably 2 or 3.

The alkyl group having 1 to 3 carbon atoms represented by R ²¹ and R ²² may be linear or branched, and examples thereof include a methyl group, an ethyl group, and a propyl group.

  Specific examples of the polyoxyethylene glycol dialkyl ether represented by the formula (α) include diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, tetraethylene glycol diethyl ether, and diethylene glycol. Examples include ethyl methyl ether, triethylene glycol ethyl methyl ether, tetraethylene glycol ethyl methyl ether, diethylene glycol-di-n-propyl ether, and diethylene glycol-di-iso-propyl ether. Among these, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, and diethylene glycol ethyl methyl ether are preferable.

In addition, as a preferable organic solvent, polyoxyethylene glycol monoalkyl ether and polyoxypropylene glycol monoalkyl ether are mentioned because they are excellent in re-solubility when the solvent-type ink in a device such as a nozzle part or a tube is solidified. It is done. Specifically, polyoxyethylene glycol monoalkyl ether represented by the formula (β) and / or polyoxypropylene glycol monoalkyl ether represented by the formula (γ) are preferable.
R ³¹ — (OC ₂ H ₄ ) _n —OH (β)
R ⁴¹ — (OC ₃ H ₆ ) _n —OH (γ)

In the above formula (β), R ³¹ represents an alkyl group having 1 to 6 carbon atoms, and n represents an integer of 3 to 6. Among the alkyl groups having 1 to 6 carbon atoms represented by R ³¹ , an alkyl group having 1 to 4 carbon atoms is preferable, and for example, a methyl group, an ethyl group, a propyl group, and a butyl group are preferable. Examples of the polyoxyethylene glycol monoalkyl ether represented by the formula (β) include triethylene glycol monomethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monobutyl ether, and pentaethylene glycol monomethyl. Examples include ether and hexaethylene glycol monomethyl ether.

Further, in the above formula (gamma), R ⁴¹ represents an alkyl group having 1 to 4 carbon atoms, n is an integer of 2-3. Among the alkyl groups having 1 to 4 carbon atoms represented by R ⁴¹ , for example, a methyl group, an ethyl group, a propyl group, and a butyl group are preferable.
Examples of the polyoxypropylene glycol monoalkyl ether represented by the formula (γ) include polypropylene glycol monoalkyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, and dipropylene. Examples include glycol monobutyl ether and tripropylene glycol monomethyl ether.

In addition to the above, (poly) alkylene glycol monoalkyl ether monoalkyl ester compounds may be mentioned. Specifically, diethylene glycol monomethyl ether monomethyl ester, diethylene glycol monoethyl ether monomethyl ester, diethylene glycol monomethyl ether monoethyl ester, diethylene glycol monomethyl ether monobutyl ester, diethylene glycol monobutyl ether monomethyl ester, diethylene glycol monobutyl ether monoethyl ester, dipropylene glycol monomethyl ether Monomethyl ester, dipropylene glycol monoethyl ether monomethyl ester, dipropylene glycol monobutyl ether monomethyl ester, dipropylene glycol monoethyl ether monoethyl ester, dipropylene glycol monoethyl ether monobutyl ester, trie Ren glycol monomethyl ether monomethyl ester, triethylene glycol monoethyl ether monomethyl ester, triethylene glycol monobutyl ether monomethyl ester, tetraethylene glycol monomethyl ether monomethyl ester, tetraethylene glycol monoethyl ether monomethyl ester, tetraethylene glycol monobutyl ether monomethyl ester, etc. Illustrated.
Among these, di- or tripropylene glycol-based compounds are preferable in terms of higher safety compared to di- or triethylene glycol-based compounds, and are particularly suitable as an ink solvent.

The polyoxyethylene glycol dialkyl ether has a boiling point of preferably 150 ° C. or higher, more preferably 180 ° C. or higher under atmospheric pressure. Although there is no restriction | limiting in particular in an upper limit, It is preferable that it is 240 degrees C or less on the function for inkjet recording. Further, the density at 20 ° C. is preferably 0.9 g / cm ³ or more, and the leveling property and drying property when used as an ink are superior to the (alkyl) monoalkyl ether monoalkyl ester compound of (poly) alkylene glycol. More suitable as a solvent.

The polyoxyethylene glycol monoalkyl ether preferably has a boiling point of 200 to 305 ° C., more preferably 240 to 305 ° C. under atmospheric pressure, from the viewpoint of imparting volatilization inhibitory properties to the ink.
The polyoxypropylene glycol monoalkyl ether preferably has a boiling point of 170 to 245 ° C., more preferably 180 to 240 ° C. under atmospheric pressure, from the viewpoint of imparting volatilization inhibition to the ink.

  As specific examples of the polyoxyalkylene glycol dialkyl ether used as (Component C) for use in the ink composition of the present invention, diethylene glycol diethyl ether and triethylene glycol diethyl ether are included, and the polyoxyalkylene glycol monoalkyl ether Preferred examples of these include dipropylene glycol monomethyl ether and triethylene glycol monomethyl ether.

  In addition to the above, triethyl citrate can also be used as a preferred organic solvent in terms of imparting volatilization inhibitory properties to the ink.

From the viewpoint of setting the flash point of the solvent ink composition to 70 ° C. or higher, it is desirable to use an organic solvent having a flash point of 70 ° C. or higher. By designing for dangerous goods No.4, No.3 petroleum or higher, the risk of ignition etc. is reduced and it can be handled relatively easily. When the flash point of solvent-based ink is set to 70 ° C or higher, it is classified as dangerous goods type 4 or type 3 or higher or higher listed in the Fire Service Act Act, and it is easy to handle during manufacturing, storage, transportation, etc. . In addition, in the case of trouble such as leakage, the risk of ignition etc. is also suppressed. If the flash point of the organic solvent is less than 70 ° C., it is difficult to make the flash point of the whole ink 70 ° C. or higher even if another solvent having a high flash point is added, but if the flash point of the main solvent is 70 ° C. or higher, Even when another solvent having a flash point lower than 70 ° C. is added thereto, the flash point of the entire ink can be easily designed to be 70 ° C. or higher by adjusting the amount of addition.
The main solvent having a flash point of 70 ° C. or higher has a boiling point of 150 ° C. or higher and a vapor pressure at 20 ° C. of 5 mmHg or lower, and is excellent in the working environment.

~ Hydrocarbon solvents ~
In the present invention, a hydrocarbon solvent can be used in addition to or separately from the above organic solvent. For pigment dispersants and resins that have an affinity for organic solvents, the addition of hydrocarbon solvents slightly reduces the solvent solubility, improves the adsorptive power to the pigment, and increases the fluidity of the ink. Storage stability can be improved. When a hydrocarbon solvent having such an effect is used, the amount is preferably determined so that the flash point of the ink does not become less than 70 ° C., and usually 1 to 30% by weight based on the total organic solvent. Is preferable, and it is more preferable to set it as 3 to 20 weight%.

  Hydrocarbon solvents are compounds made up of only carbon and hydrogen atoms, usually distillates from natural or synthetic hydrocarbon mixtures consisting of a single component or mixture, depending on the molecular structure of the alkane, Alkenes, alkynes, cycloalkanes, aromatic hydrocarbons and the like are included. Examples of such hydrocarbon solvents include paraffins such as normal paraffin and isoparaffin, naphthenes, paraffin / naphthene mixed systems, and the like. The property of the hydrocarbon solvent may be fluid or solid. Among these, an isoparaffin solvent, a normal paraffin solvent, a liquid paraffin solvent, a paraffin / naphthene solvent, and the like are preferable, and these are easily available as commercial products.

  Specifically, Isopar G, H, L, M, Noper 12, 13, and 15, isoparaffinic solvents manufactured by ExxonMobil, Exonol D110 and D130, paraffin / naphthene mixed solvents, manufactured by Idemitsu Kosan Co., Ltd. IP solvent 1620, 2028, which is an isoparaffin solvent, and normal paraffin SL, L, M, H, O type solvent L, M, H, isoparaffin solvent, which are normal paraffin solvents manufactured by Nippon Oil Corporation ISOZOL 300, 400, AF-4, AF-7, AF-5, AF-6, naphthenic solvents, Tclean N16, N20, N22, parasolvent solvents, dry solvent, dry solvent high soft, clensol, mineral spirits A, A Solvent, Hyalom 2S, Maruzen Petrochemical Co., Ltd. Marcazole R, an isoparaffin solvent manufactured by Idemitsu Kosan Co., Ltd., Idemitsu Supersol LA25, LA30, LA35, LA41, FP20, FP25, FP30, FP38, CA25, Diana Fresia P02, P05, S02 Shellsols 71 and 72, which are isoparaffinic solvents manufactured by Shell Chemicals Japan, Inc., Shellsol D100, which is a paraffin / naphthene mixed solvent, and Moresco White P, a liquid paraffinic solvent manufactured by Matsumura Oil Research Co., Ltd. -40, P-55, P-60, P-70, P-80, P-100, P-120, P-150, P-200, P-230, P-260, P-300, P-350P And Moresco Biores. A hydrocarbon type solvent can be used individually by 1 type or in mixture of 2 or more types.

  Among these hydrocarbon solvents, by adding a low molecular weight to the ink composition, the fluidity can be increased, and conversely, by adding a high molecular weight to the ink composition, the flash point can be increased. Can be increased and safety can be improved. Hydrocarbon solvents prevent the flash point from becoming too low to maintain safety, and prevent ink clogging due to improved drying performance, solubility of pigment dispersants and resins, and viewpoints of dispersibility Therefore, it is preferable that the molecular weight is high enough not to impair the fluidity of the ink composition and the flash point is 70 ° C. or higher for safety.

  As the organic solvent in the present invention, polyoxyethylene glycol dialkyl ether, polyoxyethylene glycol monoalkyl ether, polyoxypropylene glycol monoalkyl ether, water, alcohol compounds, ketone compounds, ester compounds, amine compounds Further, a mixed solvent may be used in combination with other general solvents such as glycol compounds, glycol ether compounds, and aromatic compounds. In this case, the amounts of water, alcohol compounds, etc. used in combination may be appropriately selected according to each solvent after thoroughly understanding each physical property and safety.

  As content of the organic solvent ((Component B) and (Component C)) in the inkjet ink composition of this invention, 50 weight% or more is preferable and 70 weight% or more is more preferable. When the ratio of the organic solvent is within the above range, the dispersion stability of the pigment becomes better, and the permeability to the polyvinyl chloride base material, the leveling property, and the drying property of the image area are excellent.

In the ink composition of the present invention, when the total amount of (Component A) is 100 parts by weight, the total amount of (Component B) is preferably 100 to 1,000 parts by weight, and 300 to 800 parts by weight is used. More preferably.
Furthermore, when the total amount of (Component A) is 100 parts by weight, the total amount of (Component C) is preferably 500 to 2,000 parts by weight, and 1,000 to 1,500 parts by weight. Is more preferable.
When the total amount of (Component A) is 100 parts by weight, the total amount of (Component B) and (Component C) is preferably 1,000 to 3,000 parts by weight, preferably 1,500 to 2,000. It is more preferable to use parts by weight.

  The ink composition of the present invention comprises the above (Component A), (Component B), and (Component C) as essential components. If necessary, the following (Component D) polymer dispersant and / or (Component E) A binder resin can be contained, and (Component D) and (Component E) are preferably contained.

(Component D) Polymer Dispersant The inkjet ink composition of the present invention preferably contains at least one polymer dispersant. By using a polymer dispersant, the dispersion stability of the azo pigment of (Component A) can be improved. As the polymer dispersant, a polymer pigment dispersant generally used in a solvent ink composition can be arbitrarily used. The “polymer” in the present invention means a resin having a weight average molecular weight of 3,000 or more.

  The polymer pigment dispersant preferably contains a hydrophobic group in the molecule, and more preferably is insoluble in water. The polymer pigment dispersant containing a hydrophobic group can further improve the water resistance of a recorded matter (printed matter). Examples of preferred polymer pigment dispersants include polyester pigment dispersants having a polyester chain in the molecule. By including a flexible polyester chain, the adsorptivity to the pigment is increased and the dispersibility is improved. Specifically, for example, a compound obtained by reacting a polyalkyleneimine and a polyester compound described in JP-A-54-37082, JP-A-61-174939, or the like, or described in JP-A-9-169821 A compound in which the side chain amino group of polyallylamine is modified with polyester, a graft polymer having a polyester type macromonomer described in JP-A-9-171253 as a copolymerization component, and described in JP-A-60-166318 Preferred examples include polyester polyol-added polyurethane.

  As the polymer dispersant, for example, as the polyester dispersant, for example, “SOLSPERSE” (for example, Solsperse 17000, 24000GR, 28000, 32000, 38500) manufactured by Lubrizol, “DISPERBYK” (for example, manufactured by BYK Chemie) (for example, DISPERBYK-161, 162, 167, 168), "EFKA" (for example, EFKA 4047, 4050) manufactured by Efka Additives, "Azisper" manufactured by Ajinomoto Fine Techno Co., Ltd. (for example, Addisper PB711, PN411, PA111, PB821, PB822) and the like are listed on the market.

  As the polymer dispersant, in addition to the above-mentioned commercially available products, a cationic monomer containing a basic group, an anionic monomer having an acidic group, a monomer having a hydrophobic group, and a monomer having a nonionic monomer or a hydrophilic group as necessary Those synthesized by copolymerizing with other monomers such as can be used. For details of other monomers such as a cationic monomer, an anionic monomer, a monomer having a hydrophobic group and a nonionic monomer or a monomer having a hydrophilic group, the monomers described in paragraphs 0034 to 0036 of JP-A-2004-250502 are used. Can be mentioned.

  The content of the polymer dispersant in the inkjet ink composition of the present invention is 10 to 100 with respect to the pigment represented by the formula (1), although it depends on the type of pigment and solvent, dispersion conditions, and the like. A ratio by weight is preferable, and a ratio of 20 to 80% by weight is more preferable. When the content of the polymer dispersant is in the above ratio, the dispersed particle size can be reduced, and the dispersibility can be further stabilized.

(Component E) Binder Resin The inkjet ink composition of the present invention preferably contains at least one binder resin. By containing the binder resin, it is possible to further improve the scratch resistance of the image.
As the binder resin, an anionic resin is preferable, and a (meth) acrylic resin is more preferable. The anionic resin preferably has an acid value of 5 to 150 mgKOH / g, more preferably 20 to 100 mgKOH / g, and still more preferably 30 to 80 mgKOH / g. When the acid value is 5 mgKOH / g or more, the affinity with the pigment or the medium surface is good, and when it is 150 mgKOH / g or less, the effect of improving the scratch resistance can be effectively obtained while suppressing the ink viscosity. .

  The anionic resin preferably has a weight average molecular weight of 5,000 to 100,000, more preferably 8,000 to 60,000, and still more preferably 10,000 to 30,000. When the molecular weight is 5,000 or more, the effect of steric repulsion is easily obtained when the anionic resin is adsorbed to the pigment particles in the ink composition, the effect of improving the storage stability is enhanced, and the strength of the image area is increased. When the viscosity is 100,000 or less, the ink viscosity can be suppressed and the fluidity of the ink composition can be maintained. In addition, a weight average molecular weight is calculated | required as a polystyrene conversion molecular weight by gel permeation chromatography.

The anionic resin is preferably a resin having an acryloyl group or a methacryloyl group, and a resin having a polyether structure including at least one of a polyoxyethylene structure or a polyoxypropylene structure. A resin having an acryloyl group or a methacryloyl group is a (meth) acrylic resin, and is a copolymer of methyl methacrylate or a copolymer of methyl methacrylate and butyl methacrylate in terms of excellent adhesion of the pigment dispersion to the polyvinyl chloride substrate. Polymers are preferred.
Further, the polyether structure has good affinity with the organic solvent, has excellent pigment dispersion stability, and can improve the fixability of recorded matter. Examples of such an anionic resin include a macromonomer having a polyether structure, an anionic monomer, and other monomers such as a cationic monomer, a nonionic monomer, a hydrophobic monomer, and a hydrophilic monomer as necessary. Those synthesized by polymerization can be used. As the macromonomer having a polyether structure, a macromonomer in which methoxypolyethylene glycol or methoxypolypropylene glycol is bonded to an acryloyl group or methacryloyl group directly or via an alkyl group is preferably used. As the monomer, those similar to those exemplified as the monomer for synthesizing the polymer dispersant are preferably used. The anionic resin is preferably a (meth) acrylic resin obtained by copolymerizing these monomers.

  As the macromonomer having the polyether structure, as a commercial product, PE-200, PE-350, AE-200, AE-350, AP-400, AP-550, AP-800, manufactured by NOF Corporation, 70PEP-350B, 10PEP-550B, AEP, 50POEP-800B, 50AOEP-800B, PLE, ALE, PSE, ASE, PNE, ANE, PNP, ANP, PNEP-600, PME-200, PME-400, PME-1000, AME-400, PP-500, PP-800, PP-1000, AMP-10G, AMP-20G, AMP-60G, AM-90G, manufactured by Shin-Nakamura Chemical Co., Ltd., manufactured by Osaka Organic Chemical Industries, Ltd. Biscote # 355HP, Biscote # 310, Biscote # 310HP, Biscote # 31 HG, Biscote # 312, Biscote # 700, Light acrylate EHDG-A, Light acrylate EC-A, Light acrylate MTG-A, Light acrylate 130A, Light acrylate P-200A, Light acrylate NP-4EA manufactured by Kyoeisha Chemical Co., Ltd. , Light acrylate NP-8EA, light ester MC, light ester 130MA, light ester 041MA, NK ester M-20G, NK ester M-40G, NK ester M-90G manufactured by Shin-Nakamura Chemical Co., Ltd., ADEKA Corporation Examples include Adeka Soap NE-10, Adeka Soap NE-20, and Adeka Soap NE-40.

  The content of the binder resin in the inkjet ink composition is preferably 10 to 200% by weight and more preferably 15 to 150% by weight with respect to the total amount of the pigment including the pigment represented by the formula (1). Preferably, 20 to 100% by weight is more preferable. When the content of the binder resin is 10% by weight or more, the ratio to the pigment is good and good fixability is obtained, and when it is 200% by weight or less, the ink viscosity is suppressed.

  The ink solid content of the binder resin and pigment in the ink-jet ink composition of the present invention is preferably 1 to 20% by weight, more preferably 2 to 15% by weight.

(Other ingredients)
In addition to the above-mentioned optional components (component D) and (component E), the inkjet ink composition of the present invention includes a surfactant, a surface conditioner, a leveling agent, an antifoaming agent, and an antioxidant as necessary. Well-known additives such as pH adjusters, charge imparting agents, bactericides, antiseptics, deodorants, charge control agents, wetting agents, anti-skinning agents, perfumes, and pigment derivatives may be added as optional components.

(Method for preparing ink composition)
The method for preparing the solvent-type inkjet ink composition according to the present invention is not particularly limited, and each component is a container drive medium mill such as a ball mill, a centrifugal mill or a planetary ball mill, a high-speed rotating mill such as a sand mill, or a stirring tank type. It can be prepared by stirring, mixing and dispersing with a simple dispersing machine such as a medium stirring mill such as a mill or a disper. About the addition order of each component, it is arbitrary. Preferably, the azo pigment represented by the above formula (1), the polymer dispersant and the organic solvent are premixed and then subjected to dispersion treatment, and the resulting dispersion is mixed with a resin (for example, an anionic resin) and the organic solvent. To do. In this case, at the time of addition or after addition, the mixture is uniformly mixed with a simple stirrer such as a three-one motor, a magnetic stirrer, a disper, or a homogenizer. You may mix using mixers, such as a line mixer. Further, in order to make the dispersed particles finer, they may be mixed using a dispersing machine such as a bead mill or a high-pressure jet mill. Depending on the type of pigment or polymer dispersant, an anionic resin may be added during premixing before pigment dispersion.

The inkjet ink composition of the present invention preferably has a surface tension at 25 ° C. of 20 to 40 mN / m. The surface tension is measured under the condition of 25 ° C. using an Automatic Surface Tensiometer CBVP-Z (manufactured by Kyowa Interface Science Co., Ltd.). Moreover, 1-20 mPa * s is preferable and, as for a viscosity, 3-15 mPa * s is more preferable. The viscosity is measured using a VISCOMETER TV-22 (manufactured by TOKI SANGYO CO. LTD) under conditions of 25 ° C. of the ink composition.
It is preferable that the composition ratio of the ink composition of the present invention is appropriately adjusted so that the viscosity is in the above range. By setting the viscosity at room temperature high, it is possible to avoid permeation of the ink composition into the recording medium even when a porous recording medium is used. Furthermore, it is preferable because bleeding of the ink composition upon landing of the ink composition droplet can be suppressed, and as a result, the image quality is improved.

Further, the dispersion average particle diameter of the pigment particles in the ink composition is preferably ₅₀ to 150 nm, more preferably 60 to 100 nm in terms of volume-based average particle diameter D50. When D ₅₀ is 50 nm or more, it is appropriate from the viewpoint of light resistance of the recorded material, and when it is 150 nm or less, the discharge property is good and a fine recorded material with higher resolution can be obtained. These can be easily adjusted by selecting the organic solvent and appropriately adjusting the type and amount of other components.

  Further, the surface tension at 25 ° C. of the ink composition of the present invention is preferably 20 to 35 mN / m, and more preferably 23 to 33 mN / m. When recording on various recording media such as polyolefin, PET, coated paper, and non-coated paper, 20 mN / m or more is preferable from the viewpoint of bleeding and penetration, and 35 mN / m or less is preferable in terms of wettability.

II. Inkjet recording method The inkjet recording method of the present invention includes a step of ejecting the inkjet ink composition, and a step of fixing the inkjet ink composition by applying heat to the ejected inkjet ink composition. And By performing these steps, an image of the ink composition fixed on the recording medium is formed.

  There is no restriction | limiting in particular as an inkjet recording device used for the inkjet recording method of this invention, The well-known inkjet recording device which can achieve the target resolution can be selected arbitrarily and can be used. That is, any known ink jet recording apparatus including a commercially available product can discharge the ink composition onto the recording medium in the ink jet recording method of the present invention.

Examples of the ink jet recording apparatus that can be used in the present invention include an apparatus including an ink supply system, a temperature sensor, and a heating unit.
The ink supply system includes, for example, an original tank containing the ink composition of the present invention, a supply pipe, an ink supply tank immediately before the inkjet head, a filter, and a piezo-type inkjet head. The piezo-type inkjet head preferably has a multi-size dot of 1 to 100 pl, more preferably 8 to 30 pl, preferably 320 × 320 to 4,000 × 4,000 dpi, more preferably 400 × 400 to 1,600 ×. It can be driven so that it can discharge at a resolution of 1,600 dpi, more preferably 720 × 720 dpi. In the present invention, dpi represents the number of dots per 2.54 cm.

In the ink composition of the present invention, it is desirable that the ejected ink composition is kept at a constant temperature. Therefore, the ink jet recording apparatus is preferably provided with means for stabilizing the ink composition temperature. The parts to be kept at a constant temperature are all the piping systems and members from the ink tank (intermediate tank if there is an intermediate tank) to the nozzle ejection surface. That is, heat insulation and heating can be performed from the ink supply tank to the inkjet head portion.
The temperature control method is not particularly limited, but for example, it is preferable to provide a plurality of temperature sensors in each piping portion and perform heating control according to the flow rate of the ink composition and the environmental temperature. The temperature sensor can be provided near the ink supply tank and the nozzle of the inkjet head. Moreover, it is preferable that the head unit to be heated is thermally shielded or insulated so that the apparatus main body is not affected by the temperature from the outside air. In order to shorten the printer start-up time required for heating or to reduce the loss of thermal energy, it is preferable to insulate from other parts and reduce the heat capacity of the entire heating unit.

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

  Viscosity fluctuation of the ink composition has a great influence on the change of the droplet size and the change of the droplet discharge speed, and thus causes the image quality deterioration. Therefore, it is necessary to keep the temperature of the ink composition during ejection as constant as possible. Therefore, in the present invention, the temperature control range of the ink composition is preferably set to ± 5 ° C. of the set temperature, more preferably ± 2 ° C. of the set temperature, and further preferably set temperature ± 1 ° C. .

Next, a process for fixing the solvent-type ink jet recording ink composition by applying heat to the discharged solvent-type ink jet recording ink composition will be described.
The ink composition discharged on the recording medium is fixed by evaporating the solvent by the heating means. When the binder resin is included in the ink composition, the ink composition is fixed on the surface of the recording medium by softening the binder resin.

  The heating means is not limited as long as the solvent can be dried, and a heat drum, hot air, an infrared lamp, a heat oven, a heat plate heating, or the like can be used.

In the ink jet recording method of the present invention, an ink set containing the ink composition of the present invention can be suitably used. For example, the ink composition (yellow color) of the present invention may be combined with a cyan ink composition, a magenta ink composition, or a black color composition and used as an ink set.
In order to obtain a full-color image using the ink composition of the present invention, the ink set is a combination of four dark ink compositions consisting of yellow (ink composition of the present invention), cyan, magenta, and black. It is preferably an ink set, and a dark ink composition group of five colors consisting of yellow (ink composition of the present invention), cyan, magenta, black and white, and a light cyan and light magenta ink composition group, More preferably, the ink sets are combined.
The “dark ink composition” in the present invention means an ink composition in which the pigment content exceeds 1% by weight of the entire ink composition.

  In order to obtain a color image by the ink jet recording method of the present invention, it is preferable to use an ink composition (ink set) of each color and superimpose in order from the color with the lowest brightness. Specifically, when using an ink set composed of yellow, cyan, magenta, and black ink compositions, it is preferably applied onto the recording medium in the order of yellow → cyan → magenta → black. Further, when an ink set including at least a total of seven colors of light cyan and light magenta ink composition groups and cyan, magenta, black, white, and yellow dark ink composition groups is used, In this case, it is preferable to apply the recording material in the order of white → light cyan → light magenta → yellow → cyan → magenta → black.

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

III. Printed matter The printed matter of the present invention is recorded by the inkjet recording method of the present invention. Since the printed matter of the present invention is a printed matter recorded by the inkjet recording method of the present invention, the printed matter is excellent in color reproduction, gloss, substrate adhesion, and image surface strength.

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

[Synthesis Example 1]
-Synthesis of Exemplified Compound (Pig.-1)-
A synthesis scheme of the exemplary compound (Pig.-1) is shown below.

(1) Synthesis of intermediate (a) 29.7 g (0.3 mol) of methyl cyanoacetate, 42.4 g (0.4 mol) of trimethyl orthoformate, 20.4 g (0.2 mol) of acetic anhydride, p- Toluenesulfonic acid 0.5g was added and it heated at 110 degreeC (external temperature), and it stirred for 20 hours, distilling the low boiling-point component which arises from a reaction system. The reaction solution was concentrated under reduced pressure, and then purified on a silica gel column to obtain 14.1 g of the intermediate (a) (yellow powder, yield 30%). The NMR measurement result of the obtained intermediate (a) is as follows.
¹ H-NMR (300 MHz, CDCl ₃ ) 7.96 (s, 1H), 4.15 (s, 3H), 3.81 (s, 3H)

(2) Synthesis of Intermediate (b) 150 mL of isopropanol was added to 7.4 mL (141 mmol) of methyl hydrazine and cooled to 15 ° C. (internal temperature), and 7.0 g (49. 6 mmol) was gradually added, and the mixture was heated to 50 ° C. and stirred for 1 hour and 40 minutes. After concentrating this reaction liquid under reduced pressure, silica gel column purification was performed to obtain 10.5 g of the intermediate (b) (white powder, yield 50%). The NMR measurement result of the obtained intermediate (b) is as follows.
¹ H-NMR (300 MHz, CDCl ₃ ) δ = 7.60 (s, 1H), 4.95 (brs, 2H), 3.80 (s, 3H), 3.60 (s, 3H).

(3) Synthesis of Intermediate (c) 100 mL of methanol was added to 130 mL of hydrazine monohydrate and cooled to 10 ° C. (internal temperature), and 50.0 g (336 mmol) of 4,6-dichloropyrimidine was added to this mixture. After gradually adding (internal temperature 20 ° C. or lower), the mixture was heated to 50 ° C. and stirred for 4 hours 30 minutes. Crystals precipitated from the reaction solution were collected by filtration, washed with isopropanol, and dried to obtain 43.1 g of the intermediate (c) (white powder, yield 92%). The NMR measurement result of the obtained intermediate (c) is as follows.
¹ H-NMR (300 MHz, d ₆ -DMSO) δ = 7.82 (s, 1H), 7.55 (s, 2H), 5.96 (s, 1H), 4.12 (s, 4H).

(4) Synthesis of Intermediate (d) 900 mL of water was added to 35.0 g (0.25 mol) of Intermediate (c) and 68.8 g (0.55 mol) of pivaloyl acetonitrile, and the mixture was stirred at room temperature. 1M aqueous hydrochloric acid was added dropwise to the suspension so that the pH was 3, and the mixture was heated to 50 ° C. and stirred for 8 hours. To this reaction solution, 8M aqueous potassium hydroxide solution is added dropwise to adjust the pH to 8. Further, 1M aqueous hydrochloric acid is added dropwise to adjust the pH to 6, and the precipitated crystals are collected by filtration, washed with isopropanol, dried, and dried. 83.0 g (white powder, 94% yield) of (d) was obtained. The NMR measurement result of the obtained intermediate (d) is as follows.
¹ H-NMR (300 MHz, d ₆ -DMSO) δ = 8.73 (s, 1H), 7.97 (s, 1H), 6.88 (s, 4H), 5.35 (s, 2H), 1.22 (s, 18H).

(5) Synthesis of Exemplary Compound (Pig.-1) Acetic acid (18.5 mL) was added to concentrated sulfuric acid (4.1 mL), and the mixture was stirred with ice-cooling, and 40% nitrosylsulfuric acid (3.85 g, 12.1 mmol) was added dropwise. Intermediate (b) 1.71 g (11.0 mmol) was gradually added to the mixture (internal temperature of 0 ° C. or lower), and the mixture was stirred at 0 ° C. for 2 hours. 150 mg of urea was added to this reaction solution, and the mixture was further stirred at 0 ° C. for 15 minutes to prepare diazo solution A.
50 mL of methanol was added to the intermediate (d) and dissolved by heating, and then the diazo solution A was slowly added dropwise to an ice-cooled mixture (internal temperature of 10 ° C. or lower). After the reaction solution was stirred at room temperature for 2 hours, the precipitated crystals were collected by filtration and washed with methanol to obtain crude crystals of the exemplified compound (Pig.-1). Further, water was added to the crude crystals and stirred, and then the suspension was adjusted to pH 7 with an aqueous sodium hydroxide solution, and further 20 mL of dimethylacetamide was added and stirred at 80 ° C. for 2 hours. The precipitated crystals were collected by filtration and suspended and washed with methanol. The obtained crystals were collected by filtration and dried to obtain 2.0 g (yellow powder, yield 79%) of the exemplified compound (Pig.-1).
In addition, the exemplary compound (Pig.-18), the exemplary compound (Pig.-21), and the exemplary compound (Pig.-33) were synthesized in the same manner as in the above synthesis scheme.

-Preparation of yellow pigment dispersion-
The components in the following composition were mixed and stirred with a dissolver until uniform, and the obtained preliminary dispersion was further used with a vertical bead mill (ready mill manufactured by IMEX Co., Ltd.) using 0.1 mmφ zirconia beads. It was dispersed for 3 to 6 hours to prepare yellow pigment dispersions YP-1 to YP-3.

<Composition of yellow pigment dispersion YP-1>
Exemplified compound (Pig.-1; azo pigment represented by formula (1)) 20.0 parts Solsperse 32000 (made by Lubrizol, polyester compound) 12.0 parts Diethylene glycol diethyl ether 68.0 parts

<Composition of yellow pigment dispersion YP-2>
Exemplified compound (Pig.-18; azo pigment represented by formula (1)) 20.0 parts Solsperse 32000 (made by Lubrizol, polyester compound) 12.0 parts Diethylene glycol diethyl ether 68.0 parts

<Composition of Yellow Pigment Dispersion YP-3>
-Pigment: Yellow HG AF (CI pigment yellow, 180 manufactured by Clariant) 20.0 parts-Solsperse 32000 (polyester compound manufactured by Lubrizol) 12.0 parts-Diethylene glycol diethyl ether 68.0 parts

-Measurement of particle size of yellow dispersion-
About the obtained yellow pigment dispersion YP-1, the volume standard average particle diameter D ₅₀ was measured using a light scattering diffraction type particle size distribution measuring apparatus LA910 (manufactured by Horiba, Ltd.).

-Preparation of ink composition-
Next, using the obtained yellow pigment dispersions YP-1 to YP-3, various components having the following compositions were mixed to prepare ink compositions YI-1 to YI-8.
<Composition of Ink Composition YI-1>
・ Yellow pigment dispersion YP-1 25.0 parts ・ Diethylene glycol diethyl ether (flash point 71 ° C., boiling point 189 ° C.) 34.0 parts ・ Propylene carbonate (flash point 132 ° C., boiling point 242 ° C.) 36.0 parts ・ Elvacite 2013 (resin) (manufactured by DuPont Co., Ltd., methyl methacrylate / butyl methacrylate copolymer) 5.0 parts

<Composition of ink composition YI-2>
・ Yellow pigment dispersion YP-2 25.0 parts ・ Diethylene glycol diethyl ether (flash point 71 ° C., boiling point 189 ° C.) 34.0 parts ・ Propylene carbonate (flash point 132 ° C., boiling point 242 ° C.) 36.0 parts ・ Elvacite 2013 (resin) (manufactured by DuPont Co., Ltd., methyl methacrylate / butyl methacrylate copolymer) 5.0 parts

<Composition of Ink Composition YI-3>
・ Yellow Pigment Dispersion YP-3 25.0 parts ・ Diethylene glycol diethyl ether (flash point 71 ° C., boiling point 189 ° C.) 34.0 parts ・ Propylene carbonate (flash point 132 ° C., boiling point 242 ° C.) 36.0 parts ・ Elvacite 2013 (resin) (manufactured by DuPont Co., Ltd., methyl methacrylate / butyl methacrylate copolymer) 5.0 parts

<Composition of ink composition YI-4>
・ Yellow pigment dispersion YP-1 25.0 parts ・ Diethylene glycol diethyl ether (flash point 71 ° C., boiling point 189 ° C.) 34.0 parts ・ Propylene carbonate (flash point 132 ° C., boiling point 242 ° C.) 18.0 parts ・ Ethylene Carbonate (flash point 150 ° C., boiling point 260.7 ° C.) 18.0 parts. Elvacite 2013 (resin) (manufactured by DuPont, methyl methacrylate / butyl methacrylate copolymer) 5.0 parts

<Composition of Ink Composition YI-5>
・ Yellow pigment dispersion YP-1 25.0 parts ・ Diethylene glycol diethyl ether (flash point 71 ° C., boiling point 189 ° C.) 34.0 parts ・ Propylene carbonate (flash point 132 ° C., boiling point 242 ° C.) 18.0 parts ・ N , N-dimethylimidazolidinone (flash point 121 ° C., boiling point 246 ° C.) 18.0 parts Elvacite 2013 (resin) (manufactured by DuPont, methyl methacrylate / butyl methacrylate copolymer) 5.0 parts

<Composition of Ink Composition YI-6>
-25.0 parts of the yellow pigment dispersion YP-1-Dipropylene glycol monomethyl ether (flash point 74 ° C, boiling point 190 ° C)
18.0 parts triethylene glycol diethyl ether (flash point 111 ° C., boiling point 216 ° C.)
30.5 parts triethylene glycol monomethyl ether (flash point 138 ° C, boiling point 249 ° C)
6.5 parts propylene carbonate (flash point 132 ° C., boiling point 242 ° C.) 15.0 parts Elvacite 2013 (resin) (made by DuPont, methyl methacrylate / butyl methacrylate copolymer) 5.0 parts

<Composition of Ink Composition YI-7>
-25.0 parts of the yellow pigment dispersion YP-1-Dipropylene glycol monomethyl ether (flash point 74 ° C, boiling point 190 ° C)
18.0 parts triethylene glycol diethyl ether (flash point 111 ° C., boiling point 216 ° C.)
30.5 parts triethylene glycol monomethyl ether (flash point 138 ° C, boiling point 249 ° C)
6.5 parts γ-valerolactone (lactone solvent) (flash point 81 ° C., boiling point 205-208 ° C.)
15.0 parts Elvacite 2013 (resin) (made by DuPont Co., Ltd., methyl methacrylate / butyl methacrylate copolymer) 5.0 parts

<Composition of Ink Composition YI-8>
-25.0 parts of the yellow pigment dispersion YP-1-Dipropylene glycol monomethyl ether (flash point 74 ° C, boiling point 190 ° C)
18.0 parts triethylene glycol diethyl ether (flash point 111 ° C., boiling point 216 ° C.)
30.5 parts triethylene glycol monomethyl ether (flash point 138 ° C, boiling point 249 ° C)
21.5 parts Elvacite 2013 (resin) (manufactured by DuPont Co., Ltd., methyl methacrylate / butyl methacrylate copolymer) 5.0 parts

-Evaluation-
The obtained ink compositions YI-1 to YI-8 were subjected to the following measurements and evaluations. The results of measurement and evaluation are shown in Table 1.

(1. Ink stability)
The obtained ink composition was put in a PET container, sealed, and stored in a thermostatic bath at 60 ° C. for 30 days, and the viscosity and average particle diameter after storage were measured. Further, the viscosity and average particle diameter of the ink composition before storage were also measured by the same method. The viscosity was measured with an R100 viscometer (manufactured by Toki Sangyo Co., Ltd.) at 25 ° C. and a cone rotation speed of 20 rpm. For the average particle size, a volume-based average particle size D ₅₀ was measured using a light scattering diffraction type particle size distribution measuring device LA910 (manufactured by Horiba, Ltd.). The ink stability was evaluated according to the following evaluation criteria using each measured value as an index. The evaluation results are shown in Table 1.
<Evaluation criteria>
A: Both the viscosity and the average particle size were within ± 6% of the values before storage.
B: The value of either the viscosity or the average particle diameter exceeded ± 6% of the value before storage.

(2. Discharge recovery)
The obtained ink composition was put in a PET container, sealed, and stored in a constant temperature bath at 60 ° C. for 30 days. “Image and photo finishing Pro” manufactured by Fuji Film Co., Ltd. was used as the recording medium, a 600 dpi, 256-nozzle prototype print head and an ink jet apparatus equipped with heat plate heating as the heating and fixing means were prepared. An ink composition obtained by storing in a constant temperature bath at 60 ° C. for 30 days is loaded into an ink jet apparatus, discharged from the head for 30 minutes, and then pressurized as a maintenance operation for 10 seconds at a pressure of 15 KPa, and then a clean wiper FF-390c. After wiping (made by Kuraray Co., Ltd.), the discharge was continued for another 30 minutes. After 30 minutes, drawing was performed on the recording medium (painting photo finish Pro), and immediately after that, 50 ° C. immediately below the drawing part. And dried on a heat plate heated for 2 minutes, and an image (5 cm × 5 cm) obtained by solid recording and fine line recording was observed. And the observed image was evaluated visually according to the following evaluation criteria.
<Evaluation criteria>
A: The occurrence of missing dots due to the occurrence of white spots or the like was not recognized, and a good image was obtained.
B: Image defects such as missing dots due to the occurrence of white spots were slightly observed, but were practically not hindered.
C: Many image failures such as missing dots due to white spots were observed.

(3. Adhesion to vinyl chloride resin sheet)
Similar to the evaluation of “2. Discharge recovery performance”, an inkjet apparatus having a prototype print head of 600 dpi and 256 nozzles was prepared as an inkjet recording apparatus, and the obtained ink composition was loaded into the inkjet apparatus. Recording was performed on a vinyl chloride film (Buccal 900: manufactured by Lintec Corporation). A rubbing test was performed on the recording surface (recorded image) using a rubbing tester (Model AB301, manufactured by Tester Sangyo Co., Ltd.) with a test piece (gold width 3) under a load of 200 g and 50 reciprocations. The presence or absence of ink peeling was evaluated visually according to the following evaluation criteria. The evaluation results are shown in Table 1.
<Evaluation criteria>
A: No ink peeling was observed.
B: Slight peeling of the ink was observed, but was practically no hindrance.
C: Peeling of ink was conspicuous and impeded practically.

(4. Water resistance of plain paper)
Similar to the evaluation of “2. Ejection recovery performance”, an inkjet apparatus provided with a prototype print head of 600 dpi and 256 nozzles was prepared as an inkjet recording apparatus, and the obtained ink composition YI-1 was loaded into the inkjet apparatus. The thin lines were recorded on “Picture Painting Photo Pro” manufactured by FUJIFILM Corporation, and then immersed in ion-exchanged water at 40 ° C. for 24 hours. After immersion, the presence or absence of fine line bleeding was visually observed and evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1.
<Evaluation criteria>
A: No bleeding was observed.
B: Slight bleeding was observed, but was practically no hindrance.
C: Bleeding was observed.

(5. Cock ring)
Similar to the evaluation of “2. Ejection recovery performance”, an inkjet apparatus having a prototype print head of 600 dpi and 256 nozzles is prepared as an inkjet recording apparatus, and the obtained ink composition is loaded. A solid recording was made on “Image Painting Pro” produced by Film Co., Ltd. After drying, the presence or absence of cockling (waving) in the solid image portion was visually observed. The observed images were evaluated according to the following evaluation criteria. The evaluation results are shown in Table 1.
<Evaluation criteria>
A: The occurrence of cockling (waving) was not observed.
B: The occurrence of cockling (waving) was slightly observed, but was practically no hindrance.
C: Occurrence of cockling (waving) was conspicuous and impeded practically.

(6. Bending test)
A bending test was performed as a method for evaluating the damage to the drawing substrate by the organic solvent.
In accordance with the inkjet image recording method, a solid image having an average film thickness of 4 μm was drawn using a vinyl chloride resin sheet (thickness 150 μm) as a recording medium. In the bending test, the recording material on which the image was formed was bent 30 times at 25 ° C. and evaluated by the presence or absence of cracks in the image area.
<Evaluation criteria>
A: Cracks do not occur on the sample surface.
B: Cracks occur on the sample surface after bending 20 times.
C: Cracks occur on the sample surface after bending 10 times.

In Examples, a pigment dispersion having a small particle size and high dispersion stability was obtained, and an ink composition prepared using the pigment dispersion was excellent in stability and was able to maintain good ejection recovery properties. In addition, recording on a polyvinyl chloride resin can be performed, and the adhesion of the image at this time is good, and there is no damage to the substrate. When plain paper was used, the water resistance of the image was good and the occurrence of cockling was suppressed.
On the other hand, in Comparative Example 1, the dispersibility and stability when the pigment dispersion was used were poor, and the ink stability and ejection recovery when the ink composition was used were poor. In Comparative Example 2, stability and discharge recovery properties deteriorate, damage to the polyvinyl chloride resin is large, and there is a problem in printed matter strength. On the other hand, in Comparative Example 3, stability and ejection recovery properties deteriorate, adhesion to vinyl chloride is poor, recording on polyvinyl chloride resin is difficult, and when plain paper is used, the water resistance of the image, cockling Was inferior.

Claims (10)

(Component A) an azo pigment represented by the formula (1),
(Component B) at least one organic solvent represented by formula (2) or formula (3), and
An ink-jet ink composition comprising an organic solvent other than (Component C) (Component B).

(In the formula (1), Z represents a divalent group derived from a 5- to 8-membered nitrogen-containing heterocycle, and Y ₁ , Y ₂ , R ₁₁ and R ₁₂ are each independently a hydrogen atom or 1 Represents a valent substituent, G ₁ and G ₂ each independently represent a hydrogen atom, an alkyl group, an aralkyl group, an alkenyl group, an alkynyl group, an aryl group or a heterocyclic group, and W ₁ and W ₂ each represent Independently represents an alkoxy group, an amino group, an alkyl group or an aryl group.)

(In Formula (2) and Formula (3), R ₁ , R ₂ , and R ₄ each independently represent —NR ₆ — or an oxygen atom, and R ₃ , R ₅ are —C _m H _n —. Represents a hydrocarbon group represented, may have a branch, m represents an integer of 2 to 8, n represents an integer of (2m-4), (2m-2) or 2m, R ₆ represents an alkyl group having 1 to 3 carbon atoms, a hydroxyalkyl group having 1 to 3 carbon atoms, a hydroxy group, or a hydrogen atom. The inkjet ink composition according to claim _1, wherein W ₁ and W _{2 in} formula (1) are each independently an alkoxy group having 3 or less carbon atoms, an amino group, or an alkylamino group having 3 or less carbon atoms. The inkjet ink composition according to claim 1 or 2, wherein G ₁ and G _{2 in} formula (1) are each independently an alkyl group having 3 or less carbon atoms.   The inkjet ink composition according to any one of claims 1 to 3, wherein Z in the formula (1) is a divalent group derived from a 6-membered nitrogen-containing heterocycle.   The inkjet ink composition according to any one of claims 1 to 4, wherein (Component B) is a carbonate compound.   The inkjet ink composition according to any one of claims 1 to 5, wherein (Component B) is ethylene carbonate or propylene carbonate.   The inkjet ink composition according to any one of claims 1 to 6, wherein (Component C) is a glycol ether.   The ink-jet ink composition according to any one of claims 1 to 7, further comprising (Component D) a polymer dispersant and / or (Component E) a binder resin. A step of discharging the ink-jet ink composition according to any one of claims 1 to 8 onto a recording medium; and
A step of applying heat to the ejected ink-jet ink composition to fix the ink-jet ink composition. A printed matter recorded by the ink jet recording method according to claim 9.