JP2010235895A - Inkjet ink, ink set and method for forming image using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet ink capable of suppressing the generation of curling of a medium to be recorded when the ink is imparted after realizing the good discharge stability of the ink, moreover having excellent dispersion stability of the ink and after-thermo droplet landing position accuracy and capable of preventing the generation of image deformation and to provide an ink set and method for forming image using the ink. <P>SOLUTION: In the inkjet ink containing at least (a) water-soluble organic solvent, (b) water, (c) pigment and (d) polymer dispersant, ≥70 mass% of the water-soluble organic solvent is composed of water-soluble solvent having a solubility parameter (SP value) of ≤27.5, and a free component in the polymer dispersant is ≤1.0 mass%. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an inkjet ink set, an ink set using the same, and an image forming method.

  The ink jet recording method performs recording by ejecting ink droplets from a large number of nozzles formed on an ink jet head, and the noise during the recording operation is low, the running cost is low, and various recording media are used. On the other hand, it is widely used because it can record high-quality images.

Various recording media such as plain paper, coated paper, glossy paper, OHP sheet, and back print film are commercially available for recording by the inkjet recording method described above, but the price is low for business use in general offices. Often use plain paper. As the required characteristics at this time, it is possible to reduce or suppress a curl (paper warp or curl) phenomenon that occurs when a large amount of ink is applied to the paper while satisfying the normally required characteristics.
It is also important that the occurrence of image unevenness resulting from image deformation is suppressed in the formed image. In the case of inkjet paper, the paper is fixed so that the ejected ink droplets are fixed in the form of paper. In this case, it is necessary to solve the image deformation caused by the movement of the droplets from their original positions before the droplets are dried.

  In the past, several methods have been proposed as a method for reducing or suppressing the occurrence of curling when using plain paper. For example, there is known a method for suppressing curling by using a water-based ink containing a low-polar solvent in an amount of 30% or more based on the total weight of the ink (see Patent Document 1). However, although the curl can be improved by this, the dispersion stability of the pigment particles is lowered, and the ejection stability may be deteriorated due to aggregation or thickening of the particles. On the other hand, in an inkjet ink containing a styrene- (meth) acrylic oxygen water-soluble resin, it has been proposed to improve the ejection stability of the ink in which the amount of the resin not adsorbed on the pigment is suppressed (Patent Document 2). reference).

  However, with the recent widespread use of inkjet technology, these improvements are inadequate at the moment when higher quality is required for inkjet inks, such as stabilization of quality over longer periods of continuous operation. In addition to suppressing the curl of the recording paper and improving the ejection stability, it is necessary to prevent deformation of the printed image in order to provide a higher quality image, and even when used for a long time, a high quality image can be obtained. In order to achieve this, it is also necessary to improve the landing position accuracy after the ink has elapsed.

JP 2007-145887 Japanese Patent Laid-Open No. 11-302586

  The present invention realizes good ejection stability of the ink and can suppress the curling of the recording medium when the ink is applied. Further, the dispersion stability of the ink and after the thermosetting (heat is applied by the ink jet method). An object of the present invention is to provide an ink jet ink that is excellent in landing position accuracy after being subjected to the action of energy and can prevent image deformation, an ink set using the ink, and an image forming method.

The above object has been achieved by the following means.
(1) An ink-jet ink containing at least (a) a water-soluble organic solvent, (b) water, (c) a pigment, and (d) a polymer dispersant, wherein (a) the water-soluble organic solvent 70% by mass or more consists of a water-soluble solvent having a solubility parameter (SP value) of 27.5 or less, and the amount of free component in the ink of the (d) polymer dispersant is 1.0% by mass or less. Ink jet ink.
(2) The (d) polymer dispersant has one or more acid groups forming a hydrophilic site and a repeating unit represented by any one of the following general formulas (1) to (4). The ink-jet ink as described in (1), which is characterized.

(In General Formula (1), R ₁ represents a hydrogen atom or a substituent. J represents —CO—, —COO—, —CONR ¹⁰ —, —OCO—, a methylene group, a phenylene group, or —C ₆ H _4. Represents a CO— group, R ¹⁰ represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, W represents a single bond or a divalent linking group, and A ₁ represents a heterocyclic group.)
(In General Formula (2), R _{2 to} R ₅ each independently represents a single bond, a hydrogen atom, or a substituent with W. Q ₁ is an atomic group necessary for forming a ring together with a carbon atom. _.R 1 representing a, J, and W have the same meanings as _R 1, J, and W in the general formula (1).)
(In General Formula (3), R _{6 to} R ₈ each independently represents a hydrogen atom or a substituent. X represents an anionic group that balances the cation charge on nitrogen. R ₁ , J, and W represent the general formula. (It represents the same meaning as R ₁ , J, and W in (1).)
(In the general formula (4), R ₉ represents a hydrogen atom or a substituent. Q ₂ represents an atomic group necessary for forming an unsaturated ring together with a carbon atom and a nitrogen atom. R ₁ , J , And W represent the same meaning as R ₁ , J, and W in the general formula (1).
(3) The (c) pigment is a fine particle having a difference (D ₉₀ -D ₁₀ ) between D ₉₀ and D ₁₀ defined below as a particle size distribution of 60 nm or less (1) or (2) Inkjet ink.
[D ₉₀ and D ₁₀ represent the particle sizes when the integral values of the distribution function dG = F (D) dD are 0.9 and 0.1, respectively, of the total number of pigment particles. In the above formula, G represents the number of pigment particles, and D represents the particle size. ]
(4) The inkjet ink according to any one of (1) to (3), wherein the content of the water-soluble organic solvent (a) is 5 to 30% by mass of the inkjet ink.
(5) The inkjet ink according to any one of (1) to (4), wherein the pigment (c) is a fine particle having an average particle diameter of 5 to 50 nm.
(6) The inkjet ink according to any one of (1) to (5), wherein the content of the pigment (c) is 2% by mass or more of the inkjet ink.
(7) The inkjet ink according to any one of (1) to (6), wherein the inkjet ink is a water-based ink.
(8) The ink-jet ink according to any one of (1) to (7), wherein the pigment is a build-up pigment fine particle.
(9) An ink set comprising the inkjet ink according to any one of (1) to (8) and a colorless medium containing an aggregation accelerator that promotes aggregation of the ink.
(10) A step of applying the inkjet ink according to any one of (1) to (8) to an image forming medium, a colorless medium containing an aggregation accelerator that promotes the aggregation so as to overlap the inkjet ink. An image forming method comprising the steps.
(11) A step of applying a colorless medium containing an aggregation accelerator that promotes aggregation of the inkjet ink according to any one of (1) to (8) to the image forming medium, an inkjet ink on the colorless aggregation acceleration medium The image forming method which has the process of providing.
(12) A pigment solution in which at least (a) 70% by mass or more has a solubility parameter (SP value) of 27.5 or less, (b) water (c) dissolved in a good solvent, And pigment fine particles formed by mixing with a precipitation solvent that is a poor solvent for the pigment (d) one or more acid groups forming a hydrophilic portion, and the following general formulas (1) to (4) And a repeating unit represented by any one of the following: a method for producing an inkjet ink containing a polymer dispersant,
(E) At least one of the pigment solution or the precipitation solvent contains the polymer dispersant (f) The pigment fine particles are (1) a supply pipe or the like is introduced into the stirred precipitation solvent The pigment solution is quickly added to the liquid, or the pigment solution and the solvent for precipitation are each sent in the same longitudinal direction to the long flow path, and both liquids are contacted while passing through the flow path. (2) After the pigment fine particles are taken out in the form of aggregates by acid treatment from the obtained pigment fine particle dispersion, (3) The step of contacting the aggregates with an organic solvent A method for producing an ink-jet ink, wherein the pigment fine particles are obtained through the process.

（一般式（１）において、Ｒ_１は水素原子または置換基を表す。Ｊは−ＣＯ−、−ＣＯＯ−、−ＣＯＮＲ^１０−、−ＯＣＯ−、メチレン基、フェニレン基、または−Ｃ_６Ｈ_４ＣＯ−基を表す。Ｒ^１０は水素原子、アルキル基、アリール基、またはアラルキル基を表す。Ｗは単結合または２価の連結基を表す。Ａ_１はヘテロ環基を表す。）
（一般式（２）において、Ｒ_２〜Ｒ_５は、それぞれ独立にＷとの単結合、水素原子、または置換基を表す。Ｑ_１は、炭素原子とともに環を形成するのに必要な原子群を表す。Ｒ_１、Ｊ、およびＷは一般式（１）におけるＲ_１、Ｊ、およびＷと同じ意味を表す。）
（一般式（３）において、Ｒ_６〜Ｒ_８は、それぞれ独立に水素原子または置換基を表す。Ｘは窒素上のカチオン電荷と釣り合うアニオン基を表す。Ｒ_１、Ｊ、およびＷは一般式（１）におけるＲ_１、Ｊ、およびＷと同じ意味を表す。）
（一般式（４）において、Ｒ_９は、水素原子または置換基を表す。Ｑ_２は、炭素原子および窒素原子とともに不飽和の環を形成するのに必要な原子群を表す。Ｒ_１、Ｊ、およびＷは一般式（１）におけるＲ_１、Ｊ、およびＷと同じ意味を表す。）

(In General Formula (1), R ₁ represents a hydrogen atom or a substituent. J represents —CO—, —COO—, —CONR ¹⁰ —, —OCO—, a methylene group, a phenylene group, or —C ₆ H _4. Represents a CO— group, R ¹⁰ represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, W represents a single bond or a divalent linking group, and A ₁ represents a heterocyclic group.)
(In General Formula (2), R _{2 to} R ₅ each independently represents a single bond, a hydrogen atom, or a substituent with W. Q ₁ is an atomic group necessary for forming a ring together with a carbon atom. _.R 1 representing a, J, and W have the same meanings as _R 1, J, and W in the general formula (1).)
(In General Formula (3), R _{6 to} R ₈ each independently represents a hydrogen atom or a substituent. X represents an anionic group that balances the cation charge on nitrogen. R ₁ , J, and W represent the general formula. (It represents the same meaning as R ₁ , J, and W in (1).)
(In the general formula (4), R ₉ represents a hydrogen atom or a substituent. Q ₂ represents an atomic group necessary for forming an unsaturated ring together with a carbon atom and a nitrogen atom. R ₁ , J , And W represent the same meaning as R ₁ , J, and W in the general formula (1).

  According to the ink-jet ink of the present invention, an ink set using the ink, and an image forming method, the curling of the recording medium when the ink is applied can be suppressed while achieving good ink ejection stability. In addition, it is excellent in landing position accuracy after thermo (after being subjected to the action of thermal energy by the ink dispersion stability and the ink jet method) and has an excellent effect of preventing the occurrence of image deformation.

  Hereinafter, the ink-jet ink of the present invention will be described in detail based on preferred embodiments thereof.

The ink of the present invention contains at least (a) a water-soluble organic solvent, (b) water, (c) a pigment, and (d) a polymer dispersant. Hereafter, each said component is demonstrated in detail.
<Water-soluble organic solvent>
The water-soluble organic solvent in the present invention is water-soluble, that is, has a property compatible with water. And in this invention, although the content rate of the water-soluble organic solvent whose SP value is 27.5 or less is 70 mass% or more with respect to all the water-soluble organic solvents, SP value in this invention is a solubility parameter (( SP value), which is a value represented by the square root of the molecular cohesive energy. The SP value is described in Polymer Handbook (Second Edition), Chapter IV, Solubility Parameter Values, and this value is used as the SP value in the present invention. Moreover, a unit is (MPa) ^1/2 and points out the value in 25 degreeC.
In addition, R.D. F. The value calculated by the method described in Fedors, Polymer Engineering Science, 14, p147 (1967) is used as the SP value in the present invention.

  The content of the water-soluble organic solvent having an SP value of 27.5 or less is preferably 80% by mass or more, and 90% by mass or more with respect to the total water-soluble organic solvent, from the viewpoint of curling suppression effect. Is more preferable. When the said content rate is less than 70 mass%, the curl suppression effect falls.

  The water-soluble organic solvent having an SP value of 27.5 or less in the present invention (hereinafter sometimes referred to as “first water-soluble organic solvent”) is not particularly limited as long as the SP value is 27.5 or less. From the viewpoint of curling suppression, the SP value is preferably 16 to 27.5, and more preferably 18 to 26.5.

Although the specific example of the water-soluble organic solvent whose SP value is 27.5 or less is shown below with SP value, this invention is not limited to these.
Heptaoxypropylene glycol (SP value 21.2, for example, PP-400 (trade name, manufactured by Sanyo Chemical Industries, Ltd.)),
Pentaoxyethylene pentaoxypropylene butyl ether (SP value 18.8, for example, 50HB-100 (trade name, manufactured by Sanyo Chemical Industries, Ltd.)),
Decaoxyethylene heptaoxypropylene butyl ether (SP value 18.8, for example, 50HB-260 (trade name, manufactured by Sanyo Chemical Industries, Ltd.)),
Dodecaoxyethylene dodecaoxypropylene butyl ether (SP value 18.8, for example, 50HB-400 (trade name, manufactured by Sanyo Chemical Industries, Ltd.)),
Decaoxyethylene triacontoxypropylene butyl ether (SP value 18.7, for example, PE-62 (trade name, manufactured by Sanyo Chemical Industries, Ltd.)),
Pentacosaoxyethylene triacontoxypropylene butyl ether (SP value 18.8, for example, PE-64 (trade name, manufactured by Sanyo Chemical Industries, Ltd.)).

Diethylene glycol monoethyl ether (DEGmEE) (SP value 22.4)
Diethylene glycol monobutyl ether (DEGmBE) (SP value 21.5)
Diethylene glycol diethyl ether (DEGdEE) (SP value 16.8)
Triethylene glycol monobutyl ether (TEGmBE) (SP value 21.1)
Propylene glycol monoethyl ether (PGmEE) (SP value 22.3)
Dipropylene glycol (DPG) (SP value 27.1)
Dipropylene glycol monomethyl ether (DPGmME) (SP value 21.3)
Tripropylene glycol (TPG) (SP value 24.7, for example, PP-200 (trade name, manufactured by Sanyo Chemical Industries, Ltd.))
1,2-hexanediol (SP value 27.4)
Trioxypropylene glyceryl ether (SP value 26.4, for example, GP-250 (trade name, manufactured by Sanyo Chemical Industries, Ltd.))
Dioxyethylene dioxypropylene butyl ether (SP value 20.1, for example, 50HB-55 (trade name, manufactured by Sanyo Chemical Industries, Ltd.))

POP (4) diglyceryl ether (SP value 26.1, for example, SC-P400 (trade name, manufactured by Sakamoto Pharmaceutical Co., Ltd.)),
POP (9) diglyceryl ether (SP value 22.7, for example, SC-P750 (trade name, manufactured by Sakamoto Pharmaceutical Co., Ltd.)),
POE (20) diglyceryl ether (SP value 22.4, for example, SC-E1000 (trade name, manufactured by Sakamoto Pharmaceutical Co., Ltd.)),
POE (40) diglyceryl ether (SP value 21.0, for example, SC-E2000 (trade name, manufactured by Sakamoto Pharmaceutical Co., Ltd.)).

  The water-soluble organic solvent having an SP value of 27.5 or less in the present invention is also preferably a compound represented by the following structural formula.

In the structural formula, l, m, and n each independently represent an integer of 1 or more and represent 1 + m + n = 3-15. When l + m + n is 3 or more, a sufficient curl suppressing effect can be obtained. Further, when it is 15 or less, the discharge property is improved. Among them, l + m + n is preferably 3 to 12, and more preferably 3 to 10.
In the above structural formula, AO represents at least one of an oxyethylene group (EO) and an oxypropylene group (PO), and among them, an oxypropylene group is preferable. In addition, each AO of (AO) l, (AO) m, and (AO) n may be the same or different.
Among the compounds represented by the above structural formula, compounds having the following abbreviations and structural formulas can be preferably used.

  A commercially available compound may be used as the compound. For example, POP (3) glyceryl ether is Newpol GP-250 (trade name, manufactured by Sanyo Chemical Co., Ltd.), and POP (6) glyceryl ether is Newpol GP-400 (trade name, Sanyo Chemical Co., Ltd.). Available).

  In the present invention, the water-soluble organic solvent having an SP value of 27.5 or less may be used alone or in combination of two or more.

  In the inkjet recording liquid of the present invention, in addition to the water-soluble organic solvent having an SP value of 27.5 or less, the water-soluble organic solvent having an SP value of more than 27.5 is less than 30% by mass with respect to the total water-soluble organic solvent. It may contain with the content rate of. By including a water-soluble organic solvent having an SP value of more than 27.5 (hereinafter sometimes referred to as “second water-soluble organic solvent”), the effect of preventing drying, the wetting effect or the penetration promoting effect can be more effectively achieved. Obtainable.

  Examples of the SP value exceeding 27.5 include glycerin (SP value: 33.5), diethylene glycol (SP value: 30.6), triethylene glycol (SP value: 27.8), and the like. Here, the drying prevention effect and the wetting effect mean an effect that can prevent clogging due to drying of the inkjet ink at the ink ejection port of the nozzle. As the drying inhibitor and wetting agent, a water-soluble organic solvent having a vapor pressure lower than that of water is preferable. Further, the penetration promoting effect means an effect of allowing the ink to penetrate into paper better, and a water-soluble organic solvent is preferably used.

  Examples of the second water-soluble organic solvent in the present invention include glycerin, 1,2,6-hexanetriol, trimethylolpropane, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, 2-butene-1,4-diol, 2-ethyl-1,3-hexanediol, 2-methyl-2,4-pentanediol, 1,2-octanediol, 1,2-pentanediol, 4-methyl- Alkanediols (polyhydric alcohols) such as 1,2-pentanediol; glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol, maltose, cellobiose, lactose, sucrose, trehalo Sugars such as maltotriose; sugar alcohols; hyaluronic acids; so-called solid wetting agents such as ureas; alkyl alcohols having 1 to 4 carbon atoms such as ethanol, methanol, butanol, propanol, isopropanol; ethylene glycol monomethyl ether; Ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, diethylene glycol monomethyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethylene glycol mono- n-butyl ether, ethylene glycol mono-t-butyl ether, 1-methyl-1-methoxybut Nord, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, propylene glycol mono-iso-propyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono -Glycol ethers such as n-propyl ether and dipropylene glycol mono-iso-propyl ether; 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, formamide, acetamide, dimethyl Examples include sulfoxide, sorbit, sorbitan, acetin, diacetin, triacetin, sulfolane, etc., and one or more of these can be used. The

  Among them, polyhydric alcohols are useful for the purpose of drying inhibitors and wetting agents. For example, glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 2, 3-butanediol, 1,4-butanediol, 3-methyl-1,3-butanediol, 1,5-pentanediol, tetraethylene glycol, 1,6-hexanediol, 2-methyl-2,4-pentane Examples include diol, polyethylene glycol, 1,2,4-butanetriol, 1,2,6-hexanetriol, and the like. These may be used individually by 1 type and may use 2 or more types together.

  For the purpose of the penetration enhancer, a polyol compound is preferable. Examples of the aliphatic diol include 2-ethyl-2-methyl-1,3-propanediol, 3,3-dimethyl-1,2-butanediol, 2,2-diethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2,4-dimethyl-2,4-pentanediol, 2,5-dimethyl-2,5 -Hexanediol, 5-hexene-1,2-diol, 2-ethyl-1,3-hexanediol and the like. Among these, preferred examples include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol.

The second water-soluble organic solvent used in the present invention may be used alone or in combination of two or more.
The content of the total water-soluble organic solvent in the ink jet recording liquid of the present invention is 30% by mass or less with respect to the total mass of the ink jet recording liquid from the viewpoints of ink storage stability and ejection properties, but 5-30. More preferably, it is 10 mass%, and it is still more preferable that it is 10-25 mass%.

  The ink-jet ink of the present invention is a water-based ink containing water, but the amount of water is not particularly limited. Especially, the preferable content of water is 10 to 99% by mass, more preferably 30 to 80% by mass, and still more preferably 50 to 70% by mass.

<Water-dispersible pigment>
The ink-jet ink of the present invention contains at least one pigment dispersed as a colorant. As the pigment, any pigment having a function of forming an image by coloring can be appropriately selected. However, in the present invention, the water-dispersible pigment is used from the viewpoint of being dispersed and contained so as to maintain uniformity. Is preferred. Moreover, in the range which does not impair the effect of this invention, in addition to a pigment, dye and other colored fine particles may be contained.

Specific examples of the water-dispersible pigment include pigments shown in the following (1) to (5).
(1) An encapsulated pigment, that is, a polymer emulsion in which a pigment is contained in polymer fine particles. More specifically, the pigment is coated with a hydrophilic water-insoluble resin and is made hydrophilic by a resin layer on the pigment surface. A pigment is dispersed in water.
(2) Self-dispersing pigments, that is, pigments having at least one hydrophilic group on the surface and exhibiting at least one of water dispersibility and water solubility in the absence of a dispersant, more specifically, mainly carbon black Etc. are hydrophilized by surface oxidation treatment so that the pigment alone is dispersed in water.
(3) A resin-dispersed pigment, that is, a pigment dispersed with a water-soluble polymer compound having a mass average molecular weight of 50,000 or less. (4) A surfactant-dispersed pigment, that is, a pigment dispersed with a surfactant.
(5) An organic pigment and a polymer dispersant, or a polymer compound as a dispersant is dissolved in an aprotic organic solvent in the presence of an alkali, and then this solution and water are mixed to prepare a pigment dispersion. Dispersed pigments produced by the method (dispersed pigments produced by this method are included in “build-up pigments” described later).
In the present invention, preferable examples of the pigment include (1) encapsulated pigment, (2) self-dispersing pigment, and (5) build-up pigment. Particularly preferable examples include (1) encapsulated pigment and ( 5) Build-up pigments can be mentioned.
Furthermore, when obtaining a dispersion of water-insoluble colorant particles having the above-mentioned (D ₉₀ -D ₁₀ ) ≦ 60 nm or a dispersion average particle diameter of 5 to 50 nm, it is preferable to use (5) a build-up pigment.
(5) When a build-up pigment is used, particles having a fine particle diameter and monodispersed are obtained, and further, the above-described coarse particles or coarse secondary aggregates (showing aggregates of primary particles). Is preferable in that a pigment dispersion can be obtained. Moreover, although a reason is not certain, said (5) is preferable also at the point which is excellent in light resistance compared with said (1)-(4).

  The encapsulated pigment will be described in detail. The encapsulated pigment resin is not limited, but is a polymer compound having self-dispersing ability or solubility ability in a mixed solvent of water and a water-soluble organic solvent and having an anionic group (acidic). Preferably there is. This resin usually has a number average molecular weight of about 1,000 to 100,000, and particularly preferably about 3,000 to 50,000. Further, it is preferable that this resin is dissolved in an organic solvent to form a solution. When the number average molecular weight of the resin is within this range, the function as a coating film in the pigment or as a coating film in the ink composition can be sufficiently exhibited. The resin is preferably used in the form of an alkali metal or organic amine salt.

Specific examples of encapsulated pigment resins include thermoplastic, thermosetting or modified acrylic, epoxy, polyurethane, polyether, polyamide, unsaturated polyester, phenol, silicone, and fluorine-based resins. Molecular compounds, polyvinyl chloride, vinyl acetate, polyvinyl alcohol, polyvinyl butyral, etc., polyesters such as alkyd resins, phthalic resins, melamine resins, melamine formaldehyde resins, aminoalkyd cocondensation resins, urea resins, urea resins, etc. Examples thereof include amino materials, or materials having an anionic group such as copolymers or mixtures thereof.
Among the above resins, anionic acrylic resins include, for example, acrylic monomers having an anionic group (hereinafter referred to as anionic group-containing acrylic monomers), and other monomers that can be copolymerized with these monomers as necessary. Is obtained by polymerization in a solvent. Examples of the anionic group-containing acrylic monomer include an acrylic monomer having one or more anionic groups selected from the group consisting of a carboxyl group, a sulfonic acid group, and a phosphonic group. Among these, an acrylic monomer having a carboxyl group Is particularly preferred.

Specific examples of the acrylic monomer having a carboxyl group include acrylic acid, methacrylic acid, crotonic acid, ethacrylic acid, propylacrylic acid, isopropylacrylic acid, itaconic acid, fumaric acid and the like. Among these, acrylic acid or methacrylic acid is preferable.
The encapsulated pigment can be produced by conventional physical and chemical methods using the above-described components. According to a preferred embodiment of the present invention, JP-A-9-151342, JP-A-10-140065, JP-A-11-209672, JP-A-11-172180, JP-A-10-25440, or JP-A-11-43636 It can be produced by the method disclosed in the issue.

In the present invention, the colorant is preferably a pigment (encapsulated pigment) dispersed by a phase inversion emulsification method (hereinafter also simply referred to as “phase inversion method”).
The phase inversion method refers to, for example, a self-dispersing (phase inversion emulsification) method in which a mixed melt of a resin having self-dispersing ability or solubility and a pigment is dispersed in water. Here, the mixed melt means a mixed state without dissolving, a mixed state with dissolved, or a state including both of these states. A more specific production method of the “phase inversion method” may be the same as that disclosed in JP-A-10-140065.

In the present invention, self-dispersing pigments can also be mentioned as preferred examples. The self-dispersing pigment refers to a large number of hydrophilic functional groups and / or salts thereof (hereinafter referred to as dispersibility-imparting groups) on the pigment surface directly or indirectly via an alkyl group, an alkyl ether group, an aryl group, or the like. A pigment that is bonded and dispersible in an aqueous medium without a dispersant. Here, “dispersed in an aqueous medium without a dispersant” refers to a state in which the pigment can be dispersed in an aqueous medium without using a dispersant for dispersing the pigment.
Inks containing a self-dispersing pigment as a colorant do not need to contain a dispersant as described above that is contained in order to disperse a normal pigment. It is easy to prepare ink that is excellent in ejection stability.
Examples of dispersibility-imparting groups to be bonded to the surface of the self-dispersion _{pigment, -COOH, -CO, -OH, -SO} 3 H, -PO 3 H 2 and can quaternary ammonium and exemplary salts thereof, these Is produced by bonding (grafting) an active species having a dispersibility-imparting group or a dispersibility-imparting group to the surface of the pigment by subjecting the pigment as a raw material to physical treatment or chemical treatment. Examples of the physical treatment include vacuum plasma treatment. Examples of the chemical treatment include a wet oxidation method in which the pigment surface is oxidized with an oxidizing agent in water, and a method in which a carboxyl group is bonded via a phenyl group by bonding p-aminobenzoic acid to the pigment surface. It can be illustrated.
In the present invention, preferred examples include self-dispersing pigments that are surface-treated by oxidation treatment with hypohalous acid and / or hypohalite or oxidation treatment with ozone. Commercially available products can also be used as the self-dispersing pigment, such as Microjet CW-1 (trade name; manufactured by Orient Chemical Co., Ltd.), CAB-O-JET200, CAB-O-JET300 (above trade names). ; Manufactured by Cabot Corporation).

In the present invention, examples of the dispersant used in the (1) encapsulated pigment or (3) resin-dispersed pigment include nonionic compounds, anionic compounds, cationic compounds, and amphoteric compounds.
Examples thereof include a copolymer of monomers having an α, β-ethylenically unsaturated group. Examples of monomers having an α, β-ethylenically unsaturated group include ethylene, propylene, butene, pentene, hexene, vinyl acetate, allyl acetate, acrylic acid, methacrylic acid, crotonic acid, crotonic acid ester, itaconic acid, itacone Acid monoester, maleic acid, maleic acid monoester, maleic acid diester, fumaric acid, fumaric acid monoester, vinyl sulfonic acid, styrene sulfonic acid, sulfonated vinyl naphthalene, vinyl alcohol, acrylamide, methacryloxyethyl phosphate, bismethacryloxy Styrene derivatives such as ethyl phosphate, methacryloxyethyl phenyl acid phosphate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, styrene, α-methylstyrene, vinyltoluene , Vinylcyclohexane, vinylnaphthalene, vinylnaphthalene derivatives, alkyl acrylates that may be substituted with aromatic groups, phenyl esters of acrylate, alkyl methacrylates that may be substituted with aromatic groups, phenyl esters of methacrylic acid, methacryl Acid cycloalkyl ester, crotonic acid alkyl ester, itaconic acid dialkyl ester, maleic acid dialkyl ester, vinyl alcohol, and derivatives of the above compounds.

A copolymer obtained by copolymerizing a single monomer or a plurality of monomers having the α, β-ethylenically unsaturated group is used as a polymer dispersant. Specifically, acrylic acid alkyl ester-acrylic acid copolymer, methacrylic acid alkyl ester-methacrylic acid copolymer, styrene-alkyl acrylic acid ester-acrylic acid copolymer, styrene-methacrylic acid phenyl ester-methacrylic acid, Styrene-methacrylic acid cyclohexyl ester-methacrylic acid copolymer, styrene-styrenesulfonic acid copolymer, styrene-maleic acid copolymer, styrene-methacrylic acid copolymer, styrene-acrylic acid copolymer, vinylnaphthalene-maleic Examples include acid copolymers, vinyl naphthalene-methacrylic acid copolymers, vinyl naphthalene-acrylic acid copolymers, polystyrene, polyester, and polyvinyl alcohol.
The polymer dispersant preferably has a weight average molecular weight of 2,000 to 60,000.
In addition, the addition ratio of the polymer dispersant to the pigment is preferably in the range of 10% or more and 100% or less, more preferably 20% or more and 70% or less, and still more preferably from the viewpoint of pigment dispersion stability. Is 40% or more and 50% or less.

Subsequently, the build-up pigment fine particles will be described in detail.
The build-up pigment fine particles can be produced in a solid or dispersed form by the following steps (1) to (3) and, if necessary, a step including (4) and (5).

The build-up pigment fine particles in the present invention are preferably
(1) a step of preparing a solution in which a water-insoluble colorant (organic pigment) and a dispersant are dissolved in an aprotic water-soluble organic solvent in the presence of an alkali;
(2) A step of mixing the solution and an aqueous medium to obtain a dispersion in which the water-insoluble colorant particles and the dispersing agent are dispersed in a medium containing water;
(3) a step of forming a soft aggregate obtained by agglomerating particles of the water-insoluble colorant so as to be redispersible, and separating the soft aggregate from the dispersion;
(4) A step of filtering and washing the soft aggregate with an ester solvent or a ketone solvent,
(5) The soft agglomerates can be produced by a process of releasing the aggregation and redispersing in the redispersion medium. In addition, it is preferable to dissolve the pigment derivative in either the liquid (1) or the aqueous medium. In the pigment derivative, the ratio of the amount added to the pigment is preferably 50% or less, more preferably 5% or more and 30% or less, and still more preferably 7% or more and 15% in terms of mass ratio, from the viewpoint of pigment particle stability. % Or less.

  As the aprotic solvent used in the present invention, any solvent capable of dissolving the organic pigment and the polymer compound in the presence of an alkali can be used. Further, those having a solubility in water of 5% by mass or more are preferably used, and those that are freely mixed in water are preferred.

Specifically, dimethyl sulfoxide, dimethyl imidazolidinone, sulfolane, N-methylpyrrolidone, dimethylformamide, acetonitrile, acetone, dioxane, tetramethylurea, hexamethylphosphoramide, hexamethylphosphorotriamide, pyridine, propionitrile , Butanone, cyclohexanone, tetrahydrofuran, tetrahydropyran, ethylene glycol diacetate, γ-butyrolactone, etc. are mentioned as preferred solvents, among which dimethylsulfoxide, N-methylpyrrolidone, dimethylformamide, dimethylimidazolidinone, sulfolane, acetone or acetonitrile, tetrahydrofuran Is preferred. Moreover, these can be used individually by 1 type or in combination of 2 or more types.
The proportion of the aprotic solvent used is not particularly limited, but in order to make the pigment in a better dissolved state, the ease of forming the desired fine particle diameter, and the color density of the aqueous dispersion better. It is preferable to use in the range of 2 to 500 parts by mass, and further 5 to 100 parts by mass with respect to 1 part by mass of the pigment.

  As the alkali contained in the aprotic solvent, an inorganic base such as sodium hydroxide, calcium hydroxide or barium hydroxide, or an organic base such as trialkylamine, diazabicycloundecene (DBU) or metal alkoxide is used. Among them, it is preferable to use an inorganic base. The amount of alkali to be contained is not particularly limited, but in the case of an inorganic base, it is preferably 1.0 to 30 molar equivalents, more preferably 2.0 to 25 molar equivalents, and 3 to 20 relative to the pigment. A molar equivalent is particularly preferred. In the case of an organic base, it is preferably 1.0 to 100 molar equivalents, more preferably 5.0 to 100 molar equivalents, and particularly preferably 20 to 100 molar equivalents with respect to the pigment.

  In the present invention, the aqueous solvent is water alone or a mixed solvent of water-soluble organic solvents. At this time, the addition of the organic solvent is not sufficient only with water to uniformly dissolve the pigment and the dispersant, and when only water is insufficient to obtain the viscosity necessary to flow through the flow path. It is preferable to use for such as. For example, in the case of alkali, the organic solvent is preferably an amide solvent or a sulfur-containing solvent, more preferably a sulfur-containing solvent, and particularly preferably dimethyl sulfoxide (DMSO). In the case of acidity, a carboxylic acid solvent, a sulfur solvent, or a sulfonic acid solvent is preferable, a sulfonic acid solvent is more preferable, and methanesulfonic acid is particularly preferable. In addition, you may dissolve an inorganic compound salt, the dispersing agent mentioned later, etc. in an aqueous solvent as needed.

  At this time, the embodiment in which the solution in which the water-insoluble colorant is uniformly dissolved and the aqueous solvent are mixed is not particularly limited. For example, an embodiment in which a water-based solvent is stirred and a solution of a water-insoluble coloring material is added thereto, and the solution and the water-based solvent are respectively sent to a long flow path in the same longitudinal direction and pass through the flow path. An embodiment in which both liquids are brought into contact with each other during the process to deposit organic pigment fine particles is exemplified. The former (embodiment for stirring and mixing) is particularly preferably an embodiment by adding in a liquid in which a supply pipe or the like is introduced into an aqueous solvent and a solution of a water-insoluble colorant is added therefrom. More specifically, addition in liquid can be performed using the apparatus described in paragraphs 0036 to 0047 of the pamphlet of International Publication No. WO2006 / 121018. As for the latter (embodiment in which both are mixed using a flow path), for example, paragraphs 0049 to 52 of Japanese Patent Application Laid-Open No. 2005-307154 and FIGS. 1 to 4 and paragraphs 0044 to 0050 of Japanese Patent Application No. 2006-78637. Can be used.

There are no particular restrictions on the conditions for precipitation of the water-insoluble colorant particles, and a range from normal pressure to subcritical and supercritical conditions can be selected. The temperature at normal pressure is preferably −30 to 100 ° C., more preferably −10 to 60 ° C., and particularly preferably 0 to 30 ° C. The mixing ratio of the water-insoluble colorant solution and the aqueous solvent is preferably 1/50 to 1/1 by volume, more preferably 1/20 to 2/3, and particularly preferably 1/10 to 1/2. The particle concentration in the mixed solution when the particles are precipitated is not particularly limited, but the water-insoluble colorant particles are preferably in the range of 10 to 40,000 mg, more preferably in the range of 20 to 30000 mg with respect to 1000 ml of the solvent. And particularly preferably in the range of 50 to 25000 mg.
It is also preferable to heat the mixed solution. The crystallinity of the pigment is improved (strong crystals are formed), the ink prepared using such a pigment dispersion has improved stability, and the weather resistance of the recorded image is significantly improved. The heating temperature is preferably 50 to 120 ° C, more preferably 60 to 90 ° C. The heat treatment time is preferably 10 minutes to 3 days, more preferably 1 hour to 1 day, and preferably 1 to 6 hours. If the heating temperature is too high or the heating time is too long, the particles may become coarse, which is not preferable. During this time, the liquid may be left standing or stirred.

In the preparation of the build-up pigment, the dispersant is soluble in an aprotic organic solvent in the presence of an alkali, and when a water-insoluble colorant, a solution in which the dispersant is dissolved, and an aqueous solvent are mixed, What can obtain a dispersion effect by forming pigment content particles in an aqueous solvent can be used suitably.
Preferably, a surfactant or a polymer compound, the hydrophilic part of which is composed of one or more of a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a hydroxyl group and an alkylene oxide. Used.
More preferably, those which can be stably dissolved together with an organic pigment in an aprotic organic solvent in the presence of an alkali. An aqueous dispersion of an organic pigment containing an alkali when the hydrophilic part of the dispersant is composed of only one selected from those other than the above, such as primary, secondary and tertiary amino groups and quaternary ammonium groups Although sufficient in the body, the degree of dispersion stabilization may be relatively low.
In addition, in the conventional pigment dispersion method, it is necessary to devise a method such as selecting a dispersant that can efficiently come into contact with the pigment surface in a dispersed state in the medium. However, in the present invention, both the dispersant and the pigment are dissolved. In the state of the medium, the desired action between them can be easily obtained, so there is no limitation of the dispersant based on the contact efficiency with the pigment surface as in the conventional pigment dispersion method, and a wide range of dispersion Agents can be used.

  Specific examples of the surfactant include alkylbenzene sulfonate, alkyl naphthalene sulfonate, higher fatty acid salt, sulfonate of higher fatty acid ester, sulfate ester of higher alcohol ether, sulfonate of higher alcohol ether, higher sulfonate. Anionic surfactants such as alkyl carboxylates and alkyl phosphates of alkyl sulfonamides, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, ethylene oxide adducts of acetylene glycol , Nonionic surfactants such as ethylene oxide adducts of glycerin and polyoxyethylene sorbitan fatty acid esters, and other amphoteric boundaries such as alkylbetaines and amide betaines Active agents, silicone surface active agents, including such fluorine-based surfactant, can be appropriately selected from surfactants and derivatives thereof are known.

  Specific examples of the polymer dispersant include polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl methyl ether, polyethylene oxide, polyethylene glycol, polypropylene glycol, and polyacrylamide.

  Other polymer compounds used as dispersants include styrene, styrene derivatives, vinyl naphthalene, vinyl naphthalene derivatives, aliphatic alcohol esters of α, β-ethylenically unsaturated carboxylic acids, acrylic acid, acrylic acid derivatives, methacrylic acid. Acid, methacrylic acid derivative, maleic acid, maleic acid derivative, alkenyl sulfonic acid, vinylamine, allylamine, itaconic acid, itaconic acid derivative, fumaric acid, fumaric acid derivative, vinyl acetate, vinylphosphonic acid, vinylpyrrolidone, acrylamide, N-vinyl At least two or more monomers selected from acetamide, N-vinylformamide, and derivatives thereof (of which at least one is any one of a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a hydroxyl group, and an alkylene oxide) Functional group A block copolymer composed of monomers), a random copolymer, a graft copolymer, a modified product thereof, a salt thereof, and the like.

  More specifically, the polymer compound in the present invention is preferably composed of a hydrophilic group site and a hydrophobic site, and a copolymer obtained by copolymerizing a hydrophilic monomer component and a hydrophobic monomer component is used. Is preferred. When using a polymer compound which is a polymer composed only of a hydrophobic monomer component, it may be difficult to impart good dispersion stability to the water-insoluble colorant. The hydrophilicity is a property that has a high affinity for water and is easily dissolved in water, and the hydrophobic property is a property that has a low affinity for water and is difficult to dissolve in water.

  For example, as a hydrophobic monomer component, a monomer component having a hydrophobic unit such as an isobutyl group, a t-butyl group, a phenyl group, a biphenyl group, or a naphthyl group as a structural unit can be mentioned. From the viewpoint of imparting high dispersion stability to the water-insoluble colorant, a block segment having a hydrophobic monomer such as styrene or t-butyl methacrylate as a repeating unit is preferable, but the hydrophobic monomer component is not limited thereto.

  Examples of the hydrophilic monomer component include monomer components containing a hydrophilic unit such as a structure having a functional group such as a carboxylic acid group, a sulfonic acid group, a phosphoric acid group, a hydroxyl group, and an alkylene oxide as a unit structure. . Among these, from the viewpoint of improving dispersion stability due to the charge repulsion effect between water-insoluble colorant particles, it is preferable to have a carboxylic acid group, a sulfonic acid group, and a phosphoric acid group as a unit structure, and the long-term stability of the dispersion, and From the viewpoint of improving image fixability when used as an ink, it is particularly preferable to have a carboxylic acid group as a unit structure. Specific examples include acrylic acid and methacrylic acid, or carboxylates such as inorganic salts and organic salts thereof, polyethylene glycol macromonomer, vinyl alcohol, 2-hydroxyethyl methacrylate, and the like. It is not limited to this.

  The copolymer may be a block copolymer or a copolymer having any form such as a random copolymer or a graft copolymer, but particularly when a block copolymer or a graft copolymer is used. The water-insoluble colorant is preferred because it easily imparts good dispersibility.

  As the dispersant, a polymer compound having at least one acid group that forms a hydrophilic portion and at least a repeating unit represented by any one of the following general formulas (1) to (4) is particularly preferable. The acid group is preferably selected from the group consisting of a carboxylic acid group, a sulfonic acid group, a hydroxyl group, and a phosphoric acid group.

In the general formula (1), R ₁ represents a hydrogen atom or a substituent. J represents —CO—, —COO—, —CONR ¹⁰ —, —OCO—, a methylene group, a phenylene group, or a —C ₆ H ₄ CO— group. R ¹⁰ represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group. W represents a single bond or a divalent linking group. A ₁ represents a heterocyclic group.
In General formula (2), R < ₂ > -R < ₅ > represents a single bond, a hydrogen atom, or a substituent each independently. Q ₁ represents an atomic group necessary for forming a ring together with the carbon atom. R _1, J, and W have the same meanings as _R 1, J, and W in the general formula (1).
In General formula (3), R < ₆ > -R < ₈ > represents a hydrogen atom or a substituent each independently. X represents an anionic group that balances the cationic charge on the nitrogen. R _1, J, and W have the same meanings as _R 1, J, and W in the general formula (1).
In the general formula (4), _{R 9} is a hydrogen atom or a substituent. Q ₂ represents an atomic group necessary for forming an unsaturated ring together with a carbon atom and a nitrogen atom. R _1, J, and W have the same meanings as _R 1, J, and W in the general formula (1).

The general formula (1) will be described in detail. In the general formula (1), R ₁ represents a hydrogen atom or a substituent.
As the substituent, any one selected from the substituent group Z shown below can be used. That is, an alkyl group (preferably an alkyl group having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 10 carbon atoms, such as methyl, ethyl, Iso-propyl, tert-butyl, n -Octyl, n-decyl, n-hexadecyl), a cycloalkyl group (preferably a cycloalkyl group having 3 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and particularly preferably 3 to 10 carbon atoms. Propyl, cyclopentyl, cyclohexyl, etc.), an alkenyl group (preferably an alkenyl group having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, and particularly preferably 2 to 10 carbon atoms such as vinyl and allyl. , 2-butenyl, 3-pentenyl, etc.), alkynyl groups (preferably having 2 to 30 carbon atoms, An alkynyl group having 2 to 20 carbon atoms, particularly preferably 2 to 10 carbon atoms, preferably propargyl, 3-pentynyl and the like, and an aryl group (preferably having 6 to 30 carbon atoms, more preferably carbon atoms). An aryl group having 6 to 20 carbon atoms, particularly preferably 6 to 12 carbon atoms, such as phenyl, p-methylphenyl, naphthyl, anthranyl, etc., an amino group (preferably having 0 to 30 carbon atoms, more preferably Is an amino group having 0 to 20 carbon atoms, particularly preferably 0 to 10 carbon atoms, and examples thereof include amino, methylamino, dimethylamino, diethylamino, dibenzylamino, diphenylamino, ditolylamino, and the like. Preferably 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 carbon atom. 10 alkoxy groups such as methoxy, ethoxy, butoxy, 2-ethylhexyloxy, etc.), aryloxy groups (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably An aryloxy group having 6 to 12 carbon atoms, such as phenyloxy, 1-naphthyloxy, 2-naphthyloxy, and the like, and a heterocyclic oxy group (preferably having 1 to 30 carbon atoms, more preferably having carbon atoms). 1-20, particularly preferably a heterocyclic oxy group having 1-12 carbon atoms, such as pyridyloxy, pyrazyloxy, pyrimidyloxy, quinolyloxy and the like.

  An acyl group (preferably an acyl group having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, and examples thereof include acetyl, benzoyl, formyl, pivaloyl, etc.), alkoxy A carbonyl group (preferably an alkoxycarbonyl group having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonyl and ethoxycarbonyl), aryloxy A carbonyl group (preferably an aryloxycarbonyl group having 7 to 30 carbon atoms, more preferably 7 to 20 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonyl), an acyloxy group ( Preferably 2-30 carbons, more preferably 2-20 carbons, especially preferred. Or an acyloxy group having 2 to 10 carbon atoms such as acetoxy and benzoyloxy), an acylamino group (preferably having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, and particularly preferably carbon number). 2-10 acylamino groups such as acetylamino and benzoylamino).

  An alkoxycarbonylamino group (preferably an alkoxycarbonylamino group having 2 to 30 carbon atoms, more preferably 2 to 20 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as methoxycarbonylamino), aryl Oxycarbonylamino group (preferably an aryloxycarbonylamino group having 7 to 30 carbon atoms, more preferably 7 to 20 carbon atoms, particularly preferably 7 to 12 carbon atoms, and examples thereof include phenyloxycarbonylamino group). A sulfonylamino group (preferably having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methanesulfonylamino and benzenesulfonylamino), a sulfamoyl group (Preferably 0 to 30 carbon atoms, more preferably 0 to 20 carbon atoms, particularly preferably a sulfamoyl group having 0 to 12 carbon atoms, for example sulfamoyl, methylsulfamoyl, dimethylsulfamoyl, and the like phenylsulfamoyl.),

  A carbamoyl group (preferably a carbamoyl group having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and particularly preferably 1 to 12 carbon atoms, and examples thereof include carbamoyl, methylcarbamoyl, diethylcarbamoyl, phenylcarbamoyl and the like. ), An alkylthio group (preferably an alkylthio group having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as methylthio and ethylthio), an arylthio group ( Preferably it is a C6-C30, More preferably, it is a C6-C20, Most preferably, it is a C6-C12 arylthio group, for example, phenylthio etc.), a heterocyclic thio group (preferably C1-C1). To 30, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms. A heterocyclic thio group, e.g. pyridylthio, 2-benzoxazolyl thio, and 2-benzthiazolylthio the like.),

  A sulfonyl group (preferably a sulfonyl group having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as mesyl and tosyl), a sulfinyl group (preferably A sulfinyl group having 1 to 30 carbon atoms, more preferably 1 to 20 carbon atoms, and particularly preferably 1 to 12 carbon atoms, such as methanesulfinyl, benzenesulfinyl, and the like, and a ureido group (preferably 1 carbon atom). -30, more preferably a ureido group having 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms, such as ureido, methylureido, phenylureido, etc.), phosphoric acid amide group (preferably having carbon number) 1 to 30, more preferably a phosphoric acid amide group having 1 to 20 carbon atoms, particularly preferably 1 to 12 carbon atoms. Diethyl phosphate amide, phenyl phosphate amide, etc.), hydroxy group, mercapto group, halogen atom (for example, fluorine atom, chlorine atom, bromine atom, iodine atom, more preferably fluorine atom) ,

  A cyano group, a sulfo group, a carboxyl group, an oxo group, a nitro group, a hydroxamic acid group, a sulfino group, a hydrazino group, an imino group, and a heterocyclic group (preferably having a carbon number of 1 to 30, more preferably a heterocyclic group having 1 to 12 carbon atoms) Examples of heteroatoms include nitrogen atoms, oxygen atoms, sulfur atoms, specifically imidazolyl, pyridyl, quinolyl, furyl, thienyl, piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, carbazolyl Group, azepinyl group, phenoxazine group, phenothiazine group, acridine group, acridone group, barbituric acid group, thiobarbituric acid group, etc.), silyl group (preferably having 3 to 40 carbon atoms, more preferably carbon A silyl group having 3 to 30, particularly preferably 3 to 24 carbon atoms. For example, trimethylsilyl, triphenylsilyl, etc.), a silyloxy group (preferably a silyloxy group having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, and particularly preferably 3 to 24 carbon atoms. And oxy, triphenylsilyloxy, etc.). These substituents may be further substituted with any one or more substituents selected from the above substituent group Z.

R ₁ is preferably a hydrogen atom, an alkyl group or an aryl group, and its preferred range is the same as the preferred range of the alkyl group and aryl group described for the substituent Z.

J represents —CO—, —COO—, —CONR ¹⁰ —, —OCO—, a methylene group, a phenylene group, or a —C ₆ H ₄ CO— group. Of these, J is preferably —CO—, —CONR ¹⁰ —, a phenylene group, or a —C ₆ H ₄ CO— group. R ¹⁰ represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, preferably a hydrogen atom, an alkyl group, or an aryl group, and a preferred range thereof is synonymous with a preferred range of the alkyl group or aryl group described for the substituent Z. is there.

  W represents a single bond or a divalent linking group. As the divalent linking group, for example, a linear, branched or cyclic alkylene group (preferably an alkylene group having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, still more preferably 1 to 4 carbon atoms). , For example, methylene, ethylene, propylene, butylene, pentylene, hexylene, octylene, decylene, etc.), an aralkylene group (preferably an aralkylene group having 7 to 30 carbon atoms, more preferably 7 to 13 carbon atoms, Examples thereof include benzylidene and cinnamylidene), and arylene groups (preferably an arylene group having 6 to 30 carbon atoms, more preferably 6 to 15 carbon atoms. Examples thereof include phenylene, cumenylene, mesitylene, tolylene, and xylylene. Etc.). These may further have a substituent. It is also preferable to have an ether bond in the molecule. W is preferably a single bond, an alkylene group, or an arylene group, and more preferably a single bond or an alkylene group. More preferably, it is a single bond.

A ₁ represents a heterocyclic group. The preferable range is synonymous with the preferable range of the heterocyclic group demonstrated by the substituent Z.

  The general formula (2) will be described in detail.

In the general formula (2), Q ₁ represents an atomic group necessary for forming a ring together with the carbon atom. The atomic group is a ring composed of carbon, nitrogen, oxygen, silicon, phosphorus or sulfur, preferably carbon, nitrogen, oxygen or sulfur, more preferably carbon, nitrogen or oxygen, and more Carbon or nitrogen is preferred. Q ₁ constituted by these atomic groups may be saturated or unsaturated, and may have a substituent when it can be substituted. The substituent is synonymous with the group described for Z.

R _{2 to} R ₅ represent a single bond with W, a hydrogen atom, or a substituent, and examples of the substituent are the same as those described in the substituent group Z. At least one of R _{2 to} R ₅ is a single bond.

When R _{2 to} R ₅ are other than a single bond bonded to W, preferably a hydrogen atom, alkyl group, aryl group, amino group, alkoxy group, aryloxy group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, acyloxy Group, acylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfonylamino group, carbamoyl group, sulfonyl group, hydroxy group, halogen atom, cyano group, carboxyl group, nitro group, heterocyclic group, more preferably , Hydrogen atom, alkyl group, aryl group, amino group, alkoxy group, aryloxy group, acyl group, acylamino group, sulfonylamino group, carbamoyl group, sulfonyl group, hydroxy group, halogen atom, cyano group, more preferably , Hydrogen atom, alkyl Group, a halogen atom, an acyl group, hydroxy group, a halogen atom, a cyano group. When R _{2 to} R ₅ represent a substituent, they may be bonded to each other to form a saturated or unsaturated ring. At least one of R _{2 to} R ₅ is a single bond.

R _1, J, and W have the same meanings as _R 1, J, and W in the general formula (1), the preferable ranges thereof are also the same.

  The general formula (3) will be described in detail.

R _{6 to} R ₈ each independently represents a hydrogen atom or a substituent. The substituent represents a substituted or unsubstituted alkyl group or aryl group, preferably an alkyl group. When R _{6 to} R ₇ represent a substituent, they may be bonded to each other to form a saturated or unsaturated ring.

X is an anion group that balances the cation charge on the nitrogen, preferably F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SbF ₆ ⁻ , carboxylate anion (eg acetate anion, benzoic acid). Anion), sulfonate anion (for example, methanesulfonate anion, p-toluenesulfonate anion), phosphate anion, and more preferably F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ^−. , PF ₆ ⁻ and SbF ₆ ^— , and more preferably Cl ⁻ , Br ⁻ , BF ₄ ⁻ , PF ₆ ⁻ and SbF ₆ ^— .

R _1, J, and W have the same meanings as _R 1, J, and W in the general formula (1), the preferable ranges thereof are also the same.

  The general formula (4) will be described in detail.

R ₉ represents a hydrogen atom or a substituent, and examples of the substituent are the same as those described in the substituent group Z.

R ₉ is preferably a hydrogen atom, an alkyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group, an acylamino group, a sulfonylamino group, a halogen atom, a cyano group, or a carboxyl group, more preferably a hydrogen atom or an alkyl group. , An aryl group, and an amino group, and more preferably a hydrogen atom, an alkyl group, and a halogen atom.

Q ₂ represents an atomic group necessary for forming an unsaturated ring together with a carbon atom and a nitrogen atom. The atomic group is a ring composed of carbon, nitrogen, oxygen, silicon, phosphorus or sulfur, preferably carbon, nitrogen, oxygen or sulfur, more preferably carbon, nitrogen or oxygen, and more Carbon or nitrogen is preferred. Q ₁ constituted by these atomic groups may be saturated or unsaturated, and may have a substituent when it can be substituted. The substituent is synonymous with the group described for Z.

R _1, J, and W have the same meanings as _R 1, J, and W in the general formula (1), the preferable ranges thereof are also the same.

  X represents the same meaning as X in formula (3), and its preferred range is also synonymous.

  Next, preferable combinations of the general formulas (1) to (4) will be described.

Regarding preferred combinations of general formula (1), general formula (1) is preferably (a) J is —CO—, —CONR ¹⁰ —, a phenylene group, —C ₆ H ₄ CO— group, R ¹⁰ is a hydrogen atom, an alkyl group, or an aryl group, W is a single bond, an alkylene group, or an arylene group, R ₁ is a hydrogen atom, an alkyl group, or an aryl group, and A ₁ is imidazolyl, pyridyl, In quinolyl, furyl, thienyl, piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, carbazolyl group, azepinyl group, phenoxazine group, phenothiazine group, acridine group, acridone group, barbituric acid group, thiobarbituric acid group is there.

More preferably, (b) J is —CONR ¹⁰ —, a phenylene group, R ¹⁰ is a hydrogen atom or an alkyl group, W is a single bond or an arylene group, and R ₁ is a hydrogen atom or an alkyl group. A ₁ is imidazolyl, pyridyl, quinolyl, phenoxazine group, phenothiazine group, acridine group, acridone group, barbituric acid group, thiobarbituric acid group.

More preferably, (c) J is —CONR ¹⁰ —, a phenylene group, R ¹⁰ is a hydrogen atom, W is a single bond, R ₁ is a hydrogen atom or an alkyl group, and A ₁ is imidazolyl. , Pyridyl, quinolyl, phenoxazine group, phenothiazine group, acridine group, acridone group, thiobarbituric acid group.

Particularly preferred is (d) J is —CONR ¹⁰ —, R ¹⁰ is a hydrogen atom, W is a single bond, R ₁ is a hydrogen atom, A ₁ is an imidazolyl, phenoxazine group, A phenothiazine group, an acridine group, an acridone group, and a thiobarbituric acid group.

Regarding the preferred combination of the general formula (2), the general formula (2) is preferably (a) J is —CO—, —CONR ¹⁰ —, a phenylene group, —C ₆ H ₄ CO— group, R ¹⁰ is a hydrogen atom, an alkyl group, or an aryl group, W is a single bond, an alkylene group, or an arylene group, R ₁ is a hydrogen atom, an alkyl group, or an aryl group, and Q ₁ is preferably carbon. , Nitrogen, oxygen, or sulfur, and R _{2 to} R ₅ are preferably a hydrogen atom, an alkyl group, an aryl group, an amino group, an alkoxy group, an aryloxy group other than a single bond that binds to W. Group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, acyloxy group, acylamino group, alkoxycarbonylamino group, aryloxycarbonyl group Amino group, a sulfonylamino group, a carbamoyl group, a sulfonyl group, a hydroxy group, a halogen atom, a cyano group, a carboxyl group, a nitro group, a heterocyclic group,

More preferably, (b) J is —CONR ¹⁰ —, a phenylene group, R ¹⁰ is a hydrogen atom or an alkyl group, W is a single bond or an arylene group, and R ₁ is a hydrogen atom or an alkyl group. Yes, Q ₁ is a ring composed of carbon, nitrogen or oxygen, and R _{2 to} R ₅ are hydrogen atoms, alkyl groups, aryl groups, amino groups, alkoxy groups, aryl groups other than a single bond bonded to W Oxy group, acyl group, acylamino group, sulfonylamino group, carbamoyl group, sulfonyl group, hydroxy group, halogen atom, cyano group,

More preferably, (c) J is —CONR ¹⁰ —, a phenylene group, R ¹⁰ is a hydrogen atom, W is a single bond, R ₁ is a hydrogen atom or an alkyl group, and Q ₁ is carbon. Or it is a ring comprised by nitrogen, More preferably, they are a hydrogen atom, an alkyl group, an acyl group, a hydroxy group, a halogen atom, and a cyano group. At least one of R _{2 to} R ₅ is a single bond,

Particularly preferred is (d) J is —CONR ¹⁰ —, R ¹⁰ is a hydrogen atom, W is a single bond, R ₁ is a hydrogen atom, and Q ₁ is composed of carbon or nitrogen. And more preferably a hydrogen atom, an alkyl group, a hydroxy group, a halogen atom, or a cyano group. At least one of R _{2 to} R ₅ is a single bond.

Regarding the preferred combination of general formula (3), general formula (3) is preferably (a) J is -CO-, -CONR ^10- , a phenylene group, -C ₆ H ₄ CO- group, R ¹⁰ is a hydrogen atom, an alkyl group, or an aryl group, W is a single bond, an alkylene group, or an arylene group, R ₁ is a hydrogen atom, an alkyl group, or an aryl group, and R _{6 to} R ₈ are A hydrogen atom, an alkyl group or an aryl group, and X is F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SbF ₆ ⁻ , sulfonate anion (for example, methanesulfonate anion, -toluene) Sulfonate anion),

More preferably, (b) J is —CONR ¹⁰ —, a phenylene group, R ¹⁰ is a hydrogen atom or an alkyl group, W is a single bond or an arylene group, and R ₁ is a hydrogen atom or an alkyl group. R _{6 to} R ₈ are an alkyl group or an aryl group, X is F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SbF ₆ ^— ,

More preferably, (c) J is —CONR ¹⁰ —, a phenylene group, R ¹⁰ is a hydrogen atom, W is a single bond, R ₁ is a hydrogen atom or an alkyl group, and R _{6 to} R ₈ is an alkyl group, X is Cl ⁻ , Br ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SbF ₆ ^— ,

Particularly preferred is (d) J is —CONR ¹⁰ —, R ¹⁰ is a hydrogen atom, W is a single bond, R ₁ is a hydrogen atom, and R _{6 to} R ₈ are alkyl groups. And X is Cl ⁻ , Br ⁻ , BF ₄ ⁻ , PF ₆ ⁻ or SbF ₆ ⁻ .

Regarding the preferred combination of the general formula (4), the general formula (4) is preferably (a) J is —CO—, —CONR ¹⁰ —, a phenylene group, —C ₆ H ₄ CO— group, R ¹⁰ is a hydrogen atom, an alkyl group, or an aryl group; W is a single bond, an alkylene group, or an arylene group; R ₁ is a hydrogen atom, an alkyl group, or an aryl group; and R ₉ is preferably a hydrogen atom Atoms, alkyl groups, aryl groups, amino groups, alkoxy groups, aryloxy groups, acylamino groups, sulfonylamino groups, halogen atoms, cyano groups, carboxyl groups, and Q ₂ is preferably carbon, nitrogen, oxygen, or a group of atoms selected from sulfur, a case of forming an unsaturated ring together with a carbon atom and a nitrogen atom, X ^{is, F -, Cl -, Br} -, I -, B _{^{4 -, PF 6 -, SbF}} 6 -, a sulfonate anion (such as methanesulfonic acid anion, p- toluenesulfonate anion),

More preferably, (b) J is —CONR ¹⁰ —, a phenylene group, R ¹⁰ is a hydrogen atom or an alkyl group, W is a single bond or an arylene group, and R ₁ is a hydrogen atom or an alkyl group. R ₉ is a hydrogen atom, an alkyl group, an aryl group, an amino group, or a halogen atom, and Q ₂ forms an unsaturated ring together with a group of atoms selected from carbon, nitrogen, or oxygen, and the carbon atom and the nitrogen atom X is F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SbF ₆ ⁻ ,

More preferably, (c) J is —CONR ¹⁰ —, a phenylene group, R ¹⁰ is a hydrogen atom, W is a single bond, R ₁ is a hydrogen atom or an alkyl group, and R ₉ is A hydrogen atom, an alkyl group, or a halogen atom, and Q ₂ is a case where an unsaturated ring is formed together with a group of atoms selected from carbon or nitrogen, and a carbon atom and a nitrogen atom, and X is Cl ⁻ , Br ⁻ , BF _{^{4 -, PF 6 -, SbF}} 6 - and is,

Particularly preferred is (d) J is —CONR ¹⁰ —, R ¹⁰ is a hydrogen atom, W is a single bond, R ₁ is a hydrogen atom, and Q ₂ is selected from carbon or nitrogen. In the case where an unsaturated ring is formed together with a carbon atom and a nitrogen atom, an imidazole ring is formed, and X is Cl ⁻ , Br ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SbF ₆ ^— .

  In the polymer compound having one or more kinds of acid groups forming a hydrophilic part and at least a repeating unit represented by any one of the general formulas (1) to (4) in the present invention, the polymer compound represented by the general formula (1) The polymer compound having a repeating unit is preferably a polymer compound represented by the general formula (5), and the compound represented by the general formula (2) is preferably a compound represented by the general formula (6). Those of 3) are preferably those of general formula (7), and those of general formula (4) are preferably those of general formula (8).

In the general formulas (5) to (8), R ₁₁ and R ₁₇ are hydrogen or an alkyl group. R _{12 to} R ₁₆ represent a hydrogen atom or a substituent. l, m, and n represent the mass composition ratio of the polymer, and can be arbitrarily selected within a range where l + m + n = 1. R _1, J, W and _{A 1} represents _R 1, J, the same meaning as W and _{A 1} in the general formula _{(1), R 2} in R 2 to R ₅ and _{Q 1} are the general formula (2) to R ₅ and represents the same meaning as _{Q 1,} R 6 ~R ₈ and X have the same meanings as _R 6 to R ₈ and X in the general formula (3), _{R 9} and _{Q 2} is formula (4 ) Represent the same meaning as R ₉ and Q _2, and the preferred range is also synonymous.

  Next, although the specific example of the high molecular compound which has a repeating unit represented by the said acid group and general formula (1)-(4) is shown, this invention is not limited to these.

  In addition to the repeating units represented by the general formulas (1) to (4), an α-olefinic aromatic having 8 to 20 carbon atoms such as styrene, 4-methylstyrene, 4-ethylstyrene, vinylnaphthalene, and vinylnaphthalene derivatives. C3-20 vinyl esters such as hydrocarbons, vinyl acetate, vinyl propionate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate Methyl acrylate, ethyl acrylate, butyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, methyl crotonate, ethyl crotonate, etc., olefin carboxylic acid esters having 4 to 20 carbon atoms, 4-vinyl Pyridine, 4-vinylaniline, etc. C8-20 vinyl-based aromatic amines, acrylamide, methacrylamide, benzylmethacrylamide and other C3-C20 vinyl amide compounds, 4-vinylphenol and other C8-20 olefinphenols, In addition to monomers such as butadiene, isoprene and other diene compounds having 4 to 20 carbon atoms, a polymer compound obtained as a result of combination with a monomer appropriately selected from polyfunctional monomers, macromonomers, other monomers and derivatives thereof Are also preferably used in the present invention.

  The general formula in the polymer compound (specific polymer compound) having at least one acid group forming the hydrophilic part and at least a repeating unit represented by any one of the following general formulas (1) to (4) Although the polymerization ratio in the polymer compound of the repeating unit having a group represented by (1) to (4) is not particularly limited, it is preferably 0.05 to 0.8.

The above-mentioned specific polymer compound is preferably one whose hydrophilic part is dissociated under alkaline conditions of pH 8 to 14, and the polymer compound is a simple solution as a salt dissociated in advance under alkaline conditions or a salt thereof. It may be used separately. Moreover, in this invention, in order to make said specific high molecular compound act effectively as a dispersing agent, embodiment used as the solution dissociated under alkaline conditions or its salt is preferable. Among them, it is practical and preferable in terms of stability that the group represented by the general formula (IV) is that -SO ^2- and a cation (metal cation) form a salt. From such a viewpoint, in the general formula (IV), M is preferably an alkali metal atom or an alkaline earth metal atom, and more preferably a sodium atom. Thus, whether or not the above-mentioned polymer compound or surfactant is used as a salt depends on the function and stability as a dispersant, the properties and uses required of the dispersion, the physical properties of the water-insoluble colorant, and the affinity with this. It may be determined appropriately according to the above.

In the ink of the present invention, the content of the polymer compound having at least one acid group forming a hydrophilic portion and at least a repeating unit represented by any one of the general formulas (1) to (4) is particularly limited. Although it is not, it is preferable that it is 0.1-15 mass% with respect to the total amount of ink, and it is more preferable that it is 1-5 mass%. The molecular weight of the specific polymer compound is not particularly limited, but the mass average molecular weight is preferably 1,000 to 100,000, more preferably 5,000 to 70,000, and 15,000. More preferred is ˜50,000. If it is less than 1,000, the molecular weight is small and the stability is insufficient. Even if it exceeds 100,000, the entanglement between the polymer chains becomes too large, and it becomes difficult to exhibit the function as a dispersant, so that a good dispersion state may not be maintained.
In the present invention, the term “molecular weight” means a weight average molecular weight, and the weight average molecular weight is an average molecular weight in terms of polystyrene measured by gel permeation chromatography (carrier: tetrahydrofuran) unless otherwise specified.

  The content of the polymer compound or surfactant in the dispersion is not particularly limited, and may be contained independently of other components or may be contained together with other components. That is, in the present invention, the “dispersion containing the pigment and the specific polymer compound” means that even if the polymer compound is contained in the fine particles of the pigment in the dispersion, Apart from the fine particles, the above-mentioned polymer compound may coexist. Therefore, the concept of inclusion is such that a part of the polymer compound or the like is adsorbed on the fine particles and is in a dissociation equilibrium state.

  As another preferred embodiment different from the above in the present invention, the above “one or more acid groups forming a hydrophilic portion” and “at least a repeating unit represented by any one of the general formulas (1) to (4)” It is good also as an ink containing surfactant which has.

  Moreover, as a high molecular compound used as other dispersing agents, natural high molecular compounds such as albumin, gelatin, rosin, shellac, starch, gum arabic, and sodium alginate, and modified products thereof can be preferably used. Moreover, these dispersing agents can be used individually by 1 type or in combination of 2 or more types.

  In the ink of the present invention, when considering the improvement of weather resistance, the above-described dispersant can be preferably used, but the weather resistance is improved and the low viscosity is maintained even when the concentration of the dispersion is increased. In view of the above, it is particularly preferable to use a polymer dispersant or a polymer compound that is soluble or dispersible in a specific organic solvent used in the cleaning treatment described later. In the present invention, the “dispersion” refers to a composition in which predetermined fine particles are dispersed, and the form thereof is not particularly limited, and is a liquid composition (dispersion), a paste-like composition, and a solid composition. Used to mean including things.

  In order to further improve the uniform dispersibility and storage stability of the pigment, the amount of the dispersant added to the solution in which the pigment used as a raw material in the build-up method is dissolved is 0.1% with respect to 100 parts by mass of the pigment. The range is preferably 1 to 1000 parts by mass, more preferably 1 to 500 parts by mass, and particularly preferably 10 to 100 parts by mass. If this amount is too small, the dispersion stability of the organic pigment fine particles may not be improved. The amount of the dispersant contained in the dispersion of the present invention is not particularly limited, but is practically 10 to 1000 parts by mass with respect to 100 parts by mass of the pigment.

In the dispersion obtained by the steps (1) and (2) in the build-up method, as specifically described below, the mixed solution in which the pigment particles as the water-insoluble colorant are precipitated is preferably acid-treated, It is preferable that an acid is added to the formation of the aggregate to be treated to form an aggregate of particles.
The treatment using an acid preferably includes a step of aggregating the particles with an acid, separating the particles from a solvent (dispersion medium), and performing concentration, desolvation, and desalting (deoxidation). By making the system acidic, the electrostatic repulsion force by the acidic hydrophilic portion can be reduced, and the particles can be aggregated.

As the acid used here, it is usual to agglomerate fine particles that are difficult to precipitate into a slurry, paste, powder, granule, cake (lumb), sheet, short fiber, flake, etc. Any material can be used as long as it can be efficiently separated from the solvent by a separation method.
More preferably, an acid that forms a water-soluble salt with an alkali should be used, and the acid itself is preferably highly soluble in water. Further, in order to efficiently perform desalting, the amount of acid to be added is preferably as small as possible within the range where the particles aggregate.
Specific examples include hydrochloric acid, sulfuric acid, nitric acid, acetic acid, phosphoric acid, trifluoroacetic acid, dichloroacetic acid, methanesulfonic acid and the like, with hydrochloric acid, acetic acid and sulfuric acid being particularly preferred. An aqueous dispersion of pigment particles that can be easily separated by an acid can be easily separated by a centrifugal separator, a filtration apparatus, a slurry solid-liquid separation apparatus, or the like. At this time, the degree of desalting and solvent removal can be adjusted by adding dilution water or increasing the number of decantations and washings.

  The agglomerates obtained here can be used as a paste or slurry having a high water content, but if necessary, drying such as spray drying, centrifugal drying, filtration drying or freeze drying may be used. Depending on the method, it can also be used as a fine powder.

In the aqueous dispersion, the water-insoluble colorant preferably has a crystal structure. In order to form this crystal structure, it is preferable that the soft aggregate of the particles is brought into contact with an organic solvent.
As this organic solvent, an ester solvent, a ketone solvent, an alcohol solvent, an aromatic solvent, and an aliphatic solvent are preferable, an ester solvent and a ketone solvent are more preferable, and an ester solvent is particularly preferable.

  Examples of the ester solvent include ethyl acetate, ethyl lactate, 2- (1-methoxy) propyl acetate and the like. Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone. Examples of the alcohol solvent include methanol, ethanol, n-butanol and the like. Examples of the aromatic solvent include benzene, toluene, xylene and the like. Examples of the aliphatic solvent include n-hexane and cyclohexane. Ethyl acetate, acetone, and ethyl lactate are preferable, and acetone and ethyl lactate are particularly preferable.

  Although the usage-amount of the said organic solvent is not specifically limited, For example, it is preferable to use 0.01-10000 mass parts with respect to 100 mass parts of pigments. The amount of the organic solvent contained in the aqueous dispersion forming the ink jet ink of the present invention is not particularly limited, but is practically 0.0001 to 1% by mass.

  The method of bringing the obtained aggregate into contact with the organic solvent is not particularly limited, but a method capable of separating the aggregate and the organic solvent after contacting is preferable. In addition, a method in which the organic solvent can be separated in a liquid state at the time of separation is preferable, and for example, filter filtration is preferable.

  Although the reason is not clear, the crystallite size can be increased without increasing the particle size of the water-insoluble colorant particles contained in the dispersion by performing the contact treatment with the organic solvent. That is, the crystallinity of the water-insoluble colorant particles can be increased while maintaining the primary particle size at the time of particle precipitation. Furthermore, in the redispersion treatment described later, it is possible to redisperse in water or the like while maintaining the primary particle size at the time of precipitation of particles, and high dispersion stability is also maintained. Further, by performing the above treatment, a low viscosity can be maintained even when the concentration of the aggregate redispersion is increased. Further, when used as an ink jet recording liquid, it has good ejection properties. These effects are presumed to have occurred because the dispersion was brought into contact with the organic solvent and then separated to release and remove the excess dispersant contained in the dispersion.

  At this time, since the dispersant near the surface of the water-insoluble colorant particles in the dispersion is strongly fixed to the water-insoluble colorant particles, the particle diameter of the water-insoluble colorant particles does not increase, which will be described later. Even after the redispersion treatment, high dispersion stability is maintained while maintaining the primary particle size during the precipitation of particles.

In the dispersion, it is preferable to redisperse the aggregate. Examples of the redispersion treatment include alkali treatment. That is, it is preferable to neutralize particles aggregated using an acid with an alkali and re-disperse them in water or the like with a primary particle size at the time of precipitation. Since desalting and solvent removal have already been performed, a concentrated base with few impurities can be obtained.
The alkali used here acts as a neutralizing agent for the dispersant having an acidic hydrophilic portion and increases the solubility in water. Any alkali can be used. Specifically, various organic amines such as aminomethylpropanol, dimethylaminopropanol, dimethylethanolamine, diethyltriamine, monoethanolamine, diethanolamine, triethanolamine, butyldiethanolamine, morpholine, sodium hydroxide, lithium hydroxide, potassium hydroxide And alkali metal hydroxides such as ammonia. These 1 type (s) or 2 or more types can be used in combination.

  The amount of the alkali used is not particularly limited as long as the aggregated particles can be stably redispersed in water, but when used for applications such as printing ink and ink jet printer ink, corrosion of various members. Therefore, it is preferable to use an amount that makes the pH 6 to 12, more preferably 7 to 11.

  In addition, a method different from the alkali treatment may be used depending on the dispersant used at the time of particle precipitation. For example, the redispersion treatment using the low molecular dispersant or polymer dispersion described above can be mentioned. In this case, a conventionally known dispersion treatment means may be used. For example, a disperser such as a sand mill, a bead mill, a ball mill, or a dissolver, or an ultrasonic treatment may be used. These redispersion treatments may be used in combination with the alkali treatment described above. Further, when re-dispersing the aggregated particles, a water-soluble organic solvent can be added as a re-dispersing medium to facilitate re-dispersion.

  When adding water, the said alkali, and a water-soluble organic solvent to the aggregated particle | grains, a stirring, mixing, and dispersion | distribution apparatus can be used as needed. In particular, when using a paste or slurry of an organic pigment having a high water content, it is not necessary to add water. Furthermore, heating, cooling, distillation or the like can be performed for the purpose of increasing the efficiency of redispersion and for removing unnecessary water-soluble organic solvents or excess alkali.

  The ink in the present invention can be prepared by using the dispersion and mixing, for example, each component such as a polymer compound, a surfactant, and an aqueous solvent, and dissolving or dispersing uniformly. Further, when an excessive amount of a polymer compound or additive is contained in the prepared ink, the ink can be re-prepared by appropriately removing them by a method such as centrifugation or dialysis.

<Pigment>
Examples of the pigment particles include organic pigments and inorganic pigments, and there is no particular limitation, and the pigment particles can be appropriately selected according to the purpose. Examples of organic pigments include azo pigments, polycyclic pigments, dye chelates, nitro pigments, nitroso pigments, and aniline black. Among these, azo pigments and polycyclic pigments are more preferable.

Examples of the azo pigments include azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments. Examples of the polycyclic pigment include phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinofullerone pigments.
Examples of the dye chelates include basic dye chelates and acidic dye chelates.

  Examples of the organic pigment include yellow ink pigments, 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 and the like. I. Pigment Yellow 74 is preferable. As a pigment of magenta ink, C.I. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31 32, 37, 38, 39, 40, 48 (Ca), 48 (Mn), 48: 2, 48: 3, 48: 4, 49, 49: 1, 50, 51, 52, 52: 2, 53 : 1, 53, 55, 57 (Ca), 57: 1, 60, 60: 1, 63: 1, 63: 2, 64, 64: 1, 81, 83, 87, 88, 89, 90, 101 ( Bengala), 104, 105, 106, 108 (Cadmium Red), 112, 114, 122 (Quinacridone Magenta), 123, 146, 149, 163, 166, 168, 170, 172, 177, 178, 179, 184, 185 , 190, 193, 202, 209, 19,269, etc., and C. I. Pigment violet 19, especially C.I. I. Pigment Red 122 is preferable. As a pigment of cyan ink, C.I. I. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15:34, 16, 17: 1, 22, 25, 56, 60, C.I. I. Bat blue 4, 60, 63 and the like. I. Pigment Blue 15: 3 is preferred.

  Examples of the inorganic pigment include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, and carbon black. Among these, carbon black is particularly preferable. In addition, as said carbon black, what was manufactured by well-known methods, such as a contact method, a furnace method, and a thermal method, is mentioned, for example.

As a black type, as specific examples of carbon black, Raven 7000, Raven 5750, Raven 5250, Raven 5000 ULTRA II, Rave
n 3500, Raven2000, Raven1500, Raven1250, Raven1200, Raven1190, ULTRAII, Raven1170, Raven1255, Raven1080, Raven1060, Raven700 (above, Colombian Carbon Co., Ltd.), Reg400400R, Regul400R, Regul Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400 (above, manufactured by Cabot Corporation), Color Black FW1, Color Black FW2, Color Black FW2V Color Black 18, Color Black FW200, Color Black S150, Color Black S160, Color Black S170, Printex35, Printex U, Printex V, Printex140U, Printex140V, Special Black 6, Special Black 5, Special Black 4A, Special Black4 (or, Degussa No.) 25, no. 33, no. 40, no. 45, no. 47, no. 52, no. 900, no. 2200B, no. 2300, MCF-88, MA600, MA7, MA8, MA100 (manufactured by Mitsubishi Chemical Corporation). However, it is not limited to these.

  One kind of pigment may be used alone, or a plurality of kinds of pigments may be selected from the above groups or between groups and used in combination.

  The pigment dispersed and contained in the inkjet ink of the present invention can be produced by a usual method. In the present invention, when an organic pigment is used as the pigment, it is preferably obtained by a build-up method in which a solution in which the organic pigment is dissolved and an aqueous medium are brought into contact with each other to precipitate the organic pigment. According to this method, since the surface of the pigment particle is covered and stabilized simultaneously with the formation of the particle, it is possible to form a finer particle having a narrow particle size distribution. That is, if a dispersant is present when the dissolved organic pigment is precipitated, it is considered that fine organic pigment particles can exist stably by the quick adsorption of the dispersant to the surface of the precipitated pigment.

[Dispersion average particle diameter by dynamic light scattering method (volume)]
In the present invention, the average particle diameter of the pigment refers to the volume average particle diameter (Mv), and unless otherwise specified, a Microtorac particle size distribution measuring apparatus (Version 10.1.2-211BH (trade name), manufactured by Nikkiso Co., Ltd.) And measured by a dynamic light scattering method at an appropriate concentration specified by the apparatus. That is, the dispersion state of the pigment is evaluated by a dynamic scattering method, and thereby the average particle diameter can be calculated. The principle is as follows.
The pigment particles having a particle diameter in the range of about 1 nm to 5 μm change their position and orientation from moment to moment by Brownian motion such as translation and rotation in the liquid. Therefore, when these pigment particles are irradiated with laser light and the scattered light emitted is detected, fluctuations in the scattered light intensity depending on the Brownian motion are observed. By observing the fluctuation of the scattered light intensity over time, the speed (diffusion coefficient) of the Brownian motion of the particles can be obtained, and further the size of the particles can be known.

(Measurement of average particle diameter by transmission electron microscope (TEM) observation)
Furthermore, the average particle size evaluation by observation with a transmission electron microscope (TEM) was performed by adding a diluted dispersion to Cu200 mesh with a carbon film attached and then drying, and then expanding to 100,000 times with TEM (JEOL 1200EX). From the obtained images, the major axis of 600 independent particles that did not overlap was measured, and the average value was calculated as the average particle size (hereinafter, the average particle size calculated by TEM observation is described as the TEM average particle size).

  The volume average particle diameter Mv of the pigment in the inkjet ink of the present invention is preferably 50 nm or less, more preferably 30 nm or less, and further preferably 20 nm or less. When Mv exceeds 50 nm, the landing position accuracy after a long period of time and the image deformation preventing effect are reduced. In addition, it is often difficult to produce a very small size fine particle stably, and it is preferably 5 nm or more.

<Monodispersibility of dispersion average particle diameter of pigment particles>
In the present invention, the dispersion average particle diameter of the pigment particles dispersed in the ink is preferably monodispersed. Since the dispersion average particle size of the pigment particles is monodispersed, the influence of light scattering of the particles having a large particle size can be reduced, and for example, it is formed when an aggregate is formed by printing, recording, etc. using ink. This is advantageous for controlling the packing form of aggregates. As an index for evaluating the dispersibility of the pigment contained in the ink, for example, in the number average particle size obtained by the dynamic light scattering method, the particle size distribution function of the particles is dG = F (D) dD (G is the number of particles, D Represents the primary particle size)
The difference (D ₉₀ -D ₁₀ ) between the particle size (D ₉₀ ) of the particles occupying 90% by number of the total number of particles and the particle size (D ₁₀ ) of the particles occupying 10% by number is used. it can.
In the present invention, the above difference between the _{D 90} and _{D 10} of at 60nm or less, more preferably 1～45Nm, particularly preferably 1 to 30 nm. In the present invention, unless otherwise specified, the above D ₉₀ and D ₁₀ use a Microtorac particle size distribution measuring device (Version 10.1.2-212BH (trade name), manufactured by Nikkiso Co., Ltd.) The value measured by the dynamic light scattering method at the concentration.

  By making the monodispersity of the pigment fine particles within the above range, the ink characteristics may be outstanding as compared with those outside the above range, and in particular, by making the monodispersity below the above upper limit value, the effect on ejection reliability and image stability is remarkable. It becomes. Moreover, it is not practical to make it below the lower limit because it is difficult to produce stably.

  In the present invention, the method for adjusting the average particle diameter and monodispersity of the pigment is not particularly limited. The injection rate during injection into the medium), the temperature, the addition ratio of the dispersant, the pH adjustment of the aqueous medium, and the like.

  Although there is no restriction | limiting in particular as content of the pigment in the inkjet ink of this invention, 2 mass% or more is preferable, 2-8 mass% is more preferable, and 3-6 mass% is further more preferable. If the density is low, it is difficult to obtain the required density when printing on paper. If the density is too high, it is difficult to keep the ink stable.

<Surfactant>
The ink jet recording liquid of the present invention can contain at least one surfactant. The surface tension of the ink jet recording liquid can be adjusted by adding a surfactant. As the surfactant, any of nonionic, cationic, anionic, and betaine surfactants may be used. The addition amount of the surfactant is preferably an amount for adjusting the surface tension of the ink of the present invention to 20 to 60 mN / m, more preferably 20 to 45 mN / m, and still more preferably, in order to eject droplets well by inkjet. The amount can be adjusted to 25 to 40 mN / m.
As the surfactant in the present invention, a compound having a structure having both a hydrophilic part and a hydrophobic part in the molecule can be used effectively. Anionic surfactants, cationic surfactants, amphoteric surfactants can be used. Any of the nonionic surfactants can be used. Furthermore, the above-mentioned polymer substance (polymer dispersing agent) can also be used as a surfactant.

Specific examples of anionic surfactants include, for example, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, sodium alkyldiphenyl ether disulfonate, sodium alkylnaphthalenesulfonate, sodium dialkylsulfosuccinate, sodium stearate, potassium oleate, sodium dioctyl Sulfosuccinate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, sodium dialkylsulfosuccinate, sodium stearate, sodium oleate, t-octylphenoxyethoxypolyethoxyethyl Examples include sodium sulfate, etc., and select one or more of these Rukoto can.
Specific examples of the nonionic surfactant include, for example, polyoxyethylene lauryl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene oleyl phenyl ether, polyoxyethylene nonyl phenyl ether, oxyethylene / oxypropylene block copolymer, t- Examples include octylphenoxyethyl polyethoxyethanol, nonylphenoxyethyl polyethoxyethanol, and the like, and one or more of these can be selected.
Examples of the cationic surfactant include tetraalkylammonium salts, alkylamine salts, benzalkonium salts, alkylpyridium salts, imidazolium salts, and the like. Specific examples thereof include dihydroxyethyl stearylamine and 2-heptadecenyl. -Hydroxyethyl imidazoline, lauryl dimethyl benzyl ammonium chloride, cetyl pyridinium chloride, stearamide methyl pyridium chloride and the like.
The amount of the surfactant added to the ink jet recording liquid in the invention is not particularly limited, but is preferably 1% by mass or more, more preferably 1 to 10% by mass, and still more preferably 1 to 3%. % By mass.
<Other ingredients>
The ink jet recording liquid of the present invention may contain other additives. Other additives include, for example, resin fine particles, polymer latex, ultraviolet absorbers, antifading agents, antifungal agents, pH adjusters, rust inhibitors, antioxidants, emulsion stabilizers, antiseptics, antifoaming agents, Well-known additives, such as a viscosity modifier, a dispersion stabilizer, a chelating agent, are mentioned.

Examples of the resin fine particles include acrylic resins, vinyl acetate resins, styrene-butadiene resins, vinyl chloride resins, acrylic-styrene resins, butadiene resins, styrene resins, crosslinked acrylic resins, and crosslinked styrene resins. , Benzoguanamine resin, phenol resin, silicone resin, epoxy resin, urethane resin, paraffin resin, fluorine resin, or polymer latex containing these.
Preferable examples include acrylic resins, acrylic-styrene resins, styrene resins, cross-linked acrylic resins, fine particles of cross-linked styrene resins, or polymer latex containing these.

  When preparing an ink jet ink by adding resin fine particles or polymer latex, it is preferable to add the resin fine particles or polymer latex at the same time as the pigment or the like when preparing the pigment dispersion from the viewpoint of improving fixability.

  The weight average molecular weight of the resin fine particles is preferably 10,000 or more and 200,000 or less, more preferably 100,000 or more and 200,000 or less. The average particle size of the resin fine particles is preferably in the range of 10 nm to 1 μm, more preferably in the range of 10 to 200 nm, still more preferably in the range of 20 to 100 nm, and particularly preferably in the range of 20 to 50 nm. The addition amount of the resin fine particles is preferably 0.5 to 20% by mass, more preferably 3 to 20% by mass, and further preferably 5 to 15% by mass with respect to the ink jet ink. The glass transition temperature (Tg) of the resin fine particles is preferably 30 ° C. or higher, more preferably 40 ° C. or higher, and further preferably 50 ° C. or higher.

  Further, the particle size distribution of the polymer particles of the polymer latex is not particularly limited, and any of those having a wide particle size distribution or monodispersed particle size distribution may be used. Further, two or more kinds of polymer fine particles having a monodispersed particle size distribution may be mixed and used.

  Examples of the UV absorber include benzophenone UV absorbers, benzotriazole UV absorbers, salicylate UV absorbers, cyanoacrylate UV absorbers, nickel complex salt UV absorbers, and the like.

  As the antifading agent, various organic and metal complex antifading agents can be used. Organic anti-fading agents include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, heterocycles, etc. Complex, zinc complex and the like.

  Antifungal agents include sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, p-hydroxybenzoic acid ethyl ester, 1,2-benzisothiazolin-3-one, sodium sorbate, sodium pentachlorophenol, etc. Can be mentioned. These are preferably used in the ink in an amount of 0.02 to 1.00% by mass.

  The pH adjusting agent is not particularly limited as long as it can adjust the pH to a desired value without adversely affecting the prepared inkjet recording liquid, and can be appropriately selected according to the purpose. Amines (eg, diethanolamine, triethanolamine, 2-amino-2-ethyl-1,3-propanediol), alkali metal hydroxides (eg, lithium hydroxide, sodium hydroxide, potassium hydroxide), ammonium Examples thereof include hydroxides (for example, ammonium hydroxide and quaternary ammonium hydroxides), phosphonium hydroxides, alkali metal carbonates, and the like.

  Examples of the rust inhibitor include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

  Examples of the antioxidant include phenol antioxidants (including hindered phenol antioxidants), amine antioxidants, sulfur antioxidants, phosphorus antioxidants, and the like.

  Examples of the chelating agent include sodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, sodium uramil diacetate and the like.

  The ink-jet ink of the present invention contains a polymer dispersant. Furthermore, in the inkjet ink of the present invention, the free component of the polymer dispersant is 1.0% by mass or less, more preferably 0.5% by mass or less, and further preferably 0.3% by mass or less. In the present invention, the “free component of the polymer dispersant” refers to a polymer dispersant that is not adsorbed to the pigment in the ink. Further, the “polymer dispersant” in the present invention has an action of quickly adsorbing on the surface of the deposited pigment to form fine pigment particles and preventing these particles from aggregating again.

  In the present invention, the amount of the free component of the polymer dispersant is determined according to the procedure described in the following examples unless otherwise specified.

(Physical properties of ink jet recording liquid)
The surface tension (20 ° C.) of the inkjet ink of the present invention is preferably 20 mN / m or more and 60 mN / m or less. More preferably, it is 20 mN or more and 45 mN / m or less, More preferably, it is 25 mN / m or more and 40 mN / m or less.
The surface tension is a value measured by a Wilhelmy method at a liquid temperature of 20 ° C. and 60% RH using a surface tension meter (manufactured by Kyowa Interface Science Co., Ltd., surface tension meter CBVP-Z, etc.). The surface tension can be adjusted to a desired range by containing, for example, a surfactant.

  In addition, the viscosity at 20 ° C. of the inkjet recording liquid of the present invention is preferably 5 mPa · s or more and 20 mPa · s or less, more preferably 5.5 mPa · s or more and less than 18 mPa · s, and more preferably Preferably, it is 6 mPa · s or more and less than 16 mPa · s. Furthermore, the viscosity at 40 ° C. of the inkjet recording liquid of the present invention is preferably 3 mPa · s or more and 15 mPa · s or less, more preferably 3.5 mPa · s or more and less than 12 mPa · s, and further preferably 4 mPa · s or more. The viscosity, which is less than 10 mPa · s, can be adjusted to a desired range by changing, for example, the molecular weight or content of the water-soluble organic solvent. In this invention, it can adjust to a desired range more easily by including the said 1st water-soluble organic solvent. The viscosity is measured at 20 ° C. or 40 ° C. using a TV-22 viscometer (manufactured by Toki Sangyo Co., Ltd.).

<Inkjet recording method>
As a preferred ink jet recording method for the present invention, a known image receiving material such as plain paper, resin-coated paper, for example, JP-A-8-169172, JP-A-8-27693, JP-A-2-276670, JP-A-7-276789, JP-A-9-323475, JP-A-62-238783, JP-A-10-153989, JP-A-10-217473, JP-A-10-235995 10-337947, 10-217597, 10-337947, etc. Form images on inkjet paper, film, electrophotographic co-paper, fabric, glass, metal, ceramics, etc. The method of doing is mentioned. In addition, the description of paragraph numbers 0093 to 0105 in JP-A No. 2003-306623 can be applied as an ink jet recording method preferable for the present invention.

  In forming an image, a polymer latex compound may be used in combination for the purpose of giving glossiness or water resistance or improving weather resistance. The timing of applying the latex compound to the image receiving material may be before, after, or simultaneously with the application of the colorant, and therefore the addition location may be in the image receiving paper. It may be in ink or may be used as a liquid material of polymer latex alone. Specifically, JP 2002-166638 (Japanese Patent Application 2000-363090), JP 2002-121440 (Japanese Patent Application 2000-315231), JP 2002-154201 (Japanese Patent Application 2000-354380), JP 2002-144696 ( The methods described in Japanese Patent Application No. 2000-343944) and Japanese Patent Application Laid-Open No. 2002-080759 (Japanese Patent Application No. 2000-268952) can be preferably used.

As an example of a preferable image forming method using the inkjet recording liquid of the present invention, an inkjet recording method including the following steps can be exemplified.
1st process: The process of providing the liquid composition which improves printability to a recording medium.
Second step: a step of applying an inkjet recording liquid to the recording medium to which the liquid composition has been applied.
Other steps: Other steps are not particularly limited and may be appropriately selected depending on the purpose.
For example, a drying removal process, a heat fixing process, etc. are mentioned. The drying removal step is not particularly limited except that the ink solvent in the ink jet recording liquid applied to the recording medium is removed by drying, and can be appropriately selected according to the purpose. The heat fixing step is not particularly limited except that the latex particles contained in the ink used in the ink jet recording method are melt-fixed, and can be appropriately selected depending on the purpose.

As another example of a preferable image forming method in the present invention,
1st process: The process of providing the liquid composition which improves printability to an intermediate transfer body.
Second step: a step of applying an ink jet recording liquid to the intermediate transfer body to which the liquid composition has been applied.
Third step: a step of transferring an ink image formed on the intermediate transfer member to a recording medium.
Other steps: Other steps are not particularly limited and may be appropriately selected depending on the purpose. For example, a drying removal process, a heat fixing process, etc. are mentioned.

(Liquid composition for improving printability)
As an ink jet recording method using the ink jet recording liquid of the present invention, an ink jet recording method including a step of applying a liquid composition for improving printability to a recording medium can be given as a preferred example.
As a preferred example of the liquid composition that improves the printability, a liquid composition that generates aggregates by changing the pH of the inkjet recording liquid can be exemplified. The pH of the liquid composition is preferably 1 to 6, more preferably 2 to 5, and still more preferably 3 to 5.

Examples of the aggregating component for aggregating the pigment include polyvalent metal salts, organic acids, polyallylamine and derivatives thereof.
Examples of the polyvalent metal salt include alkaline earth metals belonging to Group 2 of the periodic table (eg, magnesium, calcium), transition metals belonging to Group 3 of the periodic table (eg, lanthanum), and Group 13 of the periodic table. Mention may be made of salts of cations (for example, aluminum) and lanthanides (for example, neodymium). As these metal salts, carboxylate (formic acid, acetic acid, benzoate, etc.), nitrate, chloride, and thiocyanate are suitable. Among them, preferred are calcium salts or magnesium salts of carboxylic acids (formic acid, acetic acid, benzoates, etc.), calcium salts or magnesium salts of nitric acid, calcium chloride, magnesium chloride, and calcium salts or magnesium salts of thiocyanic acid.

  Examples of the organic acid include polyacrylic acid, acetic acid, glycolic acid, malonic acid, malic acid, maleic acid, ascorbic acid, succinic acid, glutaric acid, fumaric acid, citric acid, tartaric acid, lactic acid, sulfonic acid, and orthophosphoric acid. , Pyrrolidone carboxylic acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, derivatives of these compounds, or salts thereof are preferably selected. be able to.

The aggregating components can be used alone or in combination of two or more.
As content in the aqueous liquid composition of the aggregation component which aggregates a pigment, 1-10 mass% is preferable, More preferably, it is 1.5-7 mass%, More preferably, it is the range of 2-6 mass%. is there.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, this invention is not limited to these. In Examples, “part” or “%” is based on mass unless otherwise specified.

Example 1
-Preparation of inkjet recording liquid-
[Preparation of pigment dispersion]
First, pigment dispersion A was prepared by the following method (build-up method).
As a dispersant, 4.5 parts of the solid (dried product) of the exemplified polymer compound (2) was dissolved in 80 parts of dimethyl sulfoxide. I. 10 parts of Pigment Red 122 (quinacridone pigment) was suspended in a flask at 25 ° C. in an air atmosphere. Next, a 25% tetramethylammonium hydroxide methanol solution (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise little by little to dissolve the quinacridone pigment to obtain a deep blue-violet pigment solution. After this pigment solution was stirred for 2 hours, it was cooled and heated with impeller-type stirring blades (700 rpm) so that the amount of ion-exchanged water was 400 parts with respect to 10 parts of pigment. : 0 ° C.) using two system dispensers (manufactured by Musashi Engineering Co., Ltd., needle inner diameter: 0.58 mm, discharge pressure: 4.0 kgf / cm ² ). It was.
The average volume particle diameter of this pigment dispersion was determined by the following dynamic light scattering method, and found to be 49.4 nm (TEM average particle diameter: 34.8 nm), and the degree of monodispersity [volume The ratio of average particle diameter Mv / number average particle diameter Mn] was 1.48. Particle size distribution _(D 90 _{-D 10)} was 56 nm.

  Next, hydrochloric acid was added dropwise to the pigment dispersion to adjust the pH to 3.5, and pigment particles were aggregated from the pigment dispersion. Thereafter, the agglomerate was filtered under reduced pressure using a membrane filter having an average pore size of 0.2 μm, and washed twice with ion-exchanged water to obtain a paste of a dispersion of pigment particles that has been desalted and desolvated.

  Next, 100 parts of acetone was added to the paste, followed by stirring and ultrasonic treatment. Then, it filtered under reduced pressure using the membrane filter with an average hole diameter of 0.2 micrometer. The filtered paste was washed with ion-exchanged water and filtered under reduced pressure again using a membrane filter having an average pore size of 0.2 μm to obtain a dispersion paste containing pigment particles.

  Next, a small amount of ion-exchanged water was added to the obtained dispersion paste, and further a 1N sodium hydroxide aqueous solution (manufactured by Wako Pure Chemical Industries, Ltd.) was added, followed by addition of ion-exchanged water and stirring for 1 hour. . Thereafter, ion-exchanged water was added so that the pigment content was 10% by mass. Further, 1N aqueous sodium hydroxide solution was added to adjust the pH to 9.2, and then pigment dispersion A was obtained.

[Preparation of self-dispersing polymer particles]
360.0 g of methyl ethyl ketone was charged into a 2-liter three-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube, and the temperature was raised to 75 ° C. While maintaining the temperature in the reaction vessel at 75 ° C., 180.0 g of phenoxyethyl acrylate, 162.0 g of methyl methacrylate, 18.0 g of acrylic acid, 72 g of methyl ethyl ketone, and V-601 (trade name) (manufactured by Wako Pure Chemical Industries, Ltd.) A mixed solution consisting of 1.44 g was added dropwise at a constant speed so that the addition was completed in 2 hours. After completion of the dropwise addition, a solution consisting of 0.72 g of “V-601” and 36.0 g of methyl ethyl ketone was added, stirred for 2 hours at 75 ° C., and then a solution consisting of 0.72 g of “V-601” and 36.0 g of isopropanol was added. After stirring at 75 ° C. for 2 hours, the temperature was raised to 85 ° C., and stirring was further continued for 2 hours. The mass average molecular weight (Mw) of the obtained copolymer was 64000 (calculated in terms of polystyrene by gel permeation chromatography (GPC), the columns used were TSKgel SuperHZM-H, TSKgel SuperHZ4000, TSKgel SuperHZ200 (manufactured by Tosoh Corporation)), The acid value was 38.9 (mgKOH / g).
Next, 668.3 g of the polymerization solution was weighed, 388.3 g of isopropanol and 145.7 ml of 1 mol / L NaOH aqueous solution were added, and the temperature in the reaction vessel was raised to 80 ° C. Next, 720.1 g of distilled water was added dropwise at a rate of 20 ml / min to disperse in water. Thereafter, the temperature in the reaction vessel was maintained at 80 ° C. for 2 hours, 85 ° C. for 2 hours, and 90 ° C. for 2 hours under atmospheric pressure, and then the reaction vessel was depressurized, and isopropanol, methyl ethyl ketone, and distilled water totaled 913. 7 g was distilled off to obtain an aqueous dispersion (emulsion) of self-dispersing polymer fine particles (P-1) having a solid content concentration of 28.0%. In addition, the number of each structural unit of the compound example (P-1) shown below represents mass ratio. Hereinafter, the same applies to each structural formula.

  Using the magenta pigment dispersion A obtained above, the first water-soluble organic solvent, the surfactant, and water, each component was mixed so that the final ink composition was the following ink composition. This was passed through a 5 μm membrane filter to prepare ink 101 (inkjet recording liquid, pH = 8.8 (25 ° C.)).

After the magenta ink 101 was diluted 50 times with ultrapure water, the average volume particle size Mv determined by the dynamic light scattering method by the following method was 50.0 nm (TEM average particle size: 35.5 nm). The monodispersity index (volume ratio of volume average particle diameter Mv / number average particle diameter Mn), which is an index of monodispersity, was 1.50. It is the value which produced and measured the liquid which does not contain the particle dispersion P-2). No change was observed in the particle size after storage for 2 weeks, no sediment was observed, and no discoloration was observed.
<Composition of ink 101>
Magenta pigment (Pigment Red 122): 4%
Polymer dispersant (Exemplary polymer compound (2)): 1.4%
Self-dispersing polymer particle P-2: 5%
POP (3) glyceryl ether: 25%
(Water-soluble organic solvent, GP-250, manufactured by Sanyo Chemical Industries, Ltd.)
Orphin E1010 (manufactured by Nissin Chemical, surfactant): 1%
Ion exchange water: 64.0%

<Examples 2-7, Comparative Examples 1-5>
Ink samples 102 to 113 were prepared in the same manner as in Example 1, except that the type and amount of the water-soluble organic solvent and the type of the polymer dispersant were changed as shown in Table 1.

<Evaluation>
[Measurement of free component amount of polymer dispersant]
The inkjet ink sample prepared above was centrifuged at 80,000 rpm for 1 hour in a high-speed ultracentrifugation apparatus (trade name: Optima XL100K, manufactured by Beckman) to precipitate the pigment and collect the supernatant. The amount of the polymer dispersant in the collected supernatant was quantified by ¹³ C-NMR using a nuclear magnetic resonance analyzer (NMR) (trade name: Inova 400, manufactured by Varian Technology). A calibration curve was prepared at a concentration of 3 points using a dispersant preparation.

[Measurement of particle size and particle size distribution of the pigment _(D 90 _{-D 10)]}
The particle size and particle size distribution of the pigment were measured using a Microtroc particle size distribution analyzer (Version 10.1.2-211BH (trade name), manufactured by Nikkiso Co., Ltd.).

[Curl property]
The ink-jet recording liquid prepared above was evaluated for curl properties as follows.
<Inkjet recording apparatus>
As an ink-jet recording device, it is remodeled so that the liquid can be supplied from the outside for the Dymatics Material Printer DMP-2831 [trade name] (cartridge is for 10 pl discharge (DMC-11610 [trade name]) manufactured by Fujifilm Daimatics Co., Ltd.) Used).

<Recording medium>
As a recording medium, the following colorless ink composition (liquid composition for improving printability) was applied at 5 g / m to Tokishi Art Double Sided N (84.9 g / m ² product) (Mitsubishi Paper Co., Ltd.). ² was applied with an application bar and dried at 60 ° C. and 15 m / s for 1 minute.
The colorless ink composition was prepared by mixing the following materials.
(Colorless ink composition)
・ Citric acid: 15g
・ Orphine E1010 (manufactured by Nissin Chemical Industry Co., Ltd.) ・ ・ ・ 1g
・ Ion-exchanged water ... 84g

<Curl evaluation>
The recording medium after solid printing with an ink coating amount of 5 g / m ² was cut into 5 × 50 mm so that the curl direction was 50 mm to prepare a sample. Thereafter, the sample was allowed to stand under conditions of a temperature of 25 ° C. and a humidity of 50%, the curvature C of the sample was measured as follows, and the speed at which curling was eliminated by drying was evaluated. Table 1 shows the results of evaluation of curling properties according to the following evaluation criteria.

~ Measurement method of curvature ~
The curvature C of the sample after coating the inkjet recording liquid was measured in an environment of 25 ° C. and a relative humidity of 50%. Note that the curl value is expressed as in the following formula 1, assuming that the curl is an arc of a circle having a radius R.
C = 1 / R (m) (Formula 1)

~Evaluation criteria~
A: The curvature C of the sample 10 minutes after application did not exceed 20.
B: The curvature C of the sample one day after application did not exceed 20.
C: The curvature C of the sample 7 days after application did not exceed 20.
D: Level of curvature C of sample exceeding 20 even after 7 days from application, unacceptable level

[Evaluation of dispersion stability]
50 ml of inkjet ink is put in a sealed sample container so as not to evaporate, and left in a thermostatic bath at 60 ° C. for 2 weeks. A Microtorac particle size distribution measuring device (Version 10.1.2-211BH (trade name), Nikkiso The change rate of the volume average particle diameter (Mv) measured by the dynamic light scattering method was determined using the product, the dispersion stability was evaluated, and the results are shown in Table 1.
<Evaluation criteria>
A: Change rate of particle size is less than 10% B: Change rate of particle size is 10% or more and 30% or less C: Change rate of particle size exceeds 30% and is unacceptable for practical use

[Evaluation of post-thermo landing position accuracy]
As an inkjet recording apparatus, a print head (head: 1,200 dpi / 20 inch width full line head, ejection droplet amount: 0, 2.0, 3.5, 4.0 pL four-value recording, drive frequency: 30 kHz (recording medium conveyance An image recording apparatus having a speed of 635 mm / sec)) was prepared so that liquid could be supplied from the outside. The ink set obtained above was loaded into this apparatus, and the colorless ink composition and the ink-jet ink sample prepared as described above were supplied from the separate discharge nozzles in this order to high-quality paper (trade name: Shirai, 76. 5 m / m ² product, manufactured by Nippon Paper Industries Co., Ltd.), and a dot line of magenta was drawn. Ink jet ink was used after 2 weeks of standing at 60 ° C. after preparation. After drying, the image was fixed by fixing and heating at 100 ° C. for 10 seconds. Then, the sensory evaluation of the linearity of the magenta dot line was visually performed according to the following evaluation criteria. The results are shown in Table 1. In addition, when the degree of bending of a typical one that was determined to have significant line bending (determination “E”) was measured, a maximum deviation of 7 μm occurred from the position where the line originally landed.

<Evaluation criteria>
A: Line bending does not occur.
B: Line bending is slightly seen.
C: Line bending was observed, but it was within an allowable range for practical use.
D: Line bending is large and practically unacceptable.
E: Line bending was remarkable.

<Dispersant type>
The number in parentheses is the number of the exemplified polymer compound PVPK25: Polyvinylpyrrolidone K-25 (manufactured by IPS Japan Ltd.)
Polymer dispersant D:
Monomers were mixed in the following composition ratio, and polymer dispersant D was prepared by solution polymerization.
Methacrylic acid / styrene = 35/65 (mass ratio) (average molecular weight 18,000, acid value 200)

  From the results in Table 1, it can be seen that according to the present invention, the occurrence of curling is prevented and suppressed, and even after a long period of time, the dispersion stability and the landing position accuracy after thermostat are excellent.

(Examples 8 to 12)
-Preparation of water-based inks 201-205-
The same water-based ink 201 as the water-based ink 101 was used.
By changing the amount of the polymer composition solution and the amount of 25% tetramethylammonium hydroxide methanol solution (manufactured by Wako Pure Chemical Industries, Ltd.) with respect to the water-based ink 201, the water-based inks 202 to 205 are changed to the following Table 2. to give an average particle diameter Mv and the particle size distribution magenta aqueous ink 202-205 of different _(D 90 _{-D 10)} of pigment, as shown in. The average particle size and particle size distribution were measured in the same manner as in Example 1.

An ink set was prepared by combining the water-based inks 201 to 205 prepared as described above and the colorless ink. An inkjet ink was prepared in the same manner as in Example 1 except that the average particle diameter of the pigment particles was changed as shown in Table 2.
[Image deformability]
Using the ink jet recording apparatus and the recording medium used in the above [Curlability] evaluation, the image deformability of the ink was evaluated as follows.
A sample printed in a solid size of 5 cm × 5 cm (in which the amount of ink applied was 10 g / m ² ) was dried and fixed and heated at 90 ° C. for 10 seconds. The acceptability of image unevenness was determined according to the following evaluation criteria, and image deformability was evaluated. The results are shown in Table 2.
In the case where the occurrence of unevenness (evaluation D) is frequently observed, it typically occurs on almost the entire surface of the recording paper, which means that the practically required level is not satisfied.

<Evaluation criteria>
A: There was almost no unevenness in the image area even after drying and fixing.
B: Unevenness was not visually observed after drying, but unevenness was observed after fixing.
C: Unevenness was not visually observed before drying, but unevenness was observed after drying.
D: Unevenness was noticeable even before drying and before fixing, which was unacceptable for practical use.

  From the results in Table 2, it can be seen that the landing position accuracy and image deformation can be improved more effectively by reducing the average particle size and particle size distribution of the pigment particles.

Claims (12)

  (A) an ink-jet ink containing at least a water-soluble organic solvent, (b) water, (c) a pigment, and (d) a polymer dispersant, wherein 70% by mass of the water-soluble organic solvent (a) The above is composed of a water-soluble solvent having a solubility parameter (SP value) of 27.5 or less, and the amount of free component in the ink of (d) the polymer dispersant is 1.0% by mass or less. For ink. The (d) polymer dispersant has one or more acid groups forming a hydrophilic portion and a repeating unit represented by any one of the following general formulas (1) to (4). The inkjet ink according to claim 1.

(In General Formula (1), R ₁ represents a hydrogen atom or a substituent. J represents —CO—, —COO—, —CONR ¹⁰ —, —OCO—, a methylene group, a phenylene group, or —C ₆ H _4. Represents a CO— group, R ¹⁰ represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, W represents a single bond or a divalent linking group, and A ₁ represents a heterocyclic group.)
(In General Formula (2), R _{2 to} R ₅ each independently represents a single bond, a hydrogen atom, or a substituent with W. Q ₁ is an atomic group necessary for forming a ring together with a carbon atom. _.R 1 representing a, J, and W have the same meanings as _R 1, J, and W in the general formula (1).)
(In General Formula (3), R _{6 to} R ₈ each independently represents a hydrogen atom or a substituent. X represents an anionic group that balances the cation charge on nitrogen. R ₁ , J, and W represent the general formula. (It represents the same meaning as R ₁ , J, and W in (1).)
(In the general formula (4), R ₉ represents a hydrogen atom or a substituent. Q ₂ represents an atomic group necessary for forming an unsaturated ring together with a carbon atom and a nitrogen atom. R ₁ , J , And W represent the same meaning as R ₁ , J, and W in the general formula (1). Wherein (c) a pigment, the difference _(D 90 _{-D 10)} is according to claim 1 or 2 inkjet ink, wherein the following fine 60nm between _{D 90} and _{D 10,} defined below as the particle diameter distribution.
[D ₉₀ and D ₁₀ represent the particle sizes when the integral values of the distribution function dG = F (D) dD are 0.9 and 0.1, respectively, of the total number of pigment particles. In the above formula, G represents the number of pigment particles, and D represents the particle size. ]   The inkjet ink according to any one of claims 1 to 3, wherein the content of the water-soluble organic solvent (a) is 5 to 30% by mass of the inkjet ink.   The inkjet ink according to claim 1, wherein the pigment (c) is a fine particle having an average particle diameter of 5 to 50 nm.   6. The inkjet ink according to claim 1, wherein the content of the pigment (c) is 2% by mass or more of the inkjet ink.   The inkjet ink according to claim 1, wherein the inkjet ink is a water-based ink. The ink-jet ink according to claim 1, wherein the pigment is a build-up pigment fine particle.   An ink set comprising the inkjet ink according to claim 1 and a colorless medium containing an aggregation accelerator that promotes aggregation of the ink.   An image forming method comprising: applying the inkjet ink according to any one of claims 1 to 8 to an image forming medium; and applying a colorless medium containing an aggregation accelerator that promotes the aggregation so as to overlap the inkjet ink. Method.   A step of applying a colorless medium containing an aggregation accelerator that promotes aggregation of the inkjet ink according to claim 1 to an image forming medium, and a step of applying inkjet ink on the colorless aggregation promoting medium. An image forming method. At least (a) 70% by mass or more of a water-soluble organic solvent having a solubility parameter (SP value) of 27.5 or less, (b) water (c) a pigment solution dissolved in a good solvent, compatible with the good solvent, and Pigment fine particles formed by mixing a precipitation solvent that is a poor solvent for the pigment (d) one or more acid groups forming a hydrophilic portion, and any of the following general formulas (1) to (4) A method for producing an ink-jet ink containing a polymer dispersant characterized by having a repeating unit represented by:
(E) At least one of the pigment solution or the precipitation solvent contains the polymer dispersant (f) The pigment fine particles are (1) a supply pipe or the like is introduced into the stirred precipitation solvent The pigment solution is quickly added to the liquid, or the pigment solution and the solvent for precipitation are each sent in the same longitudinal direction to the long flow path, and both liquids are contacted while passing through the flow path. (2) After the pigment fine particles are taken out in the form of aggregates by acid treatment from the obtained pigment fine particle dispersion, (3) The step of contacting the aggregates with an organic solvent A method for producing an ink-jet ink, wherein the pigment fine particles are obtained through the process.

(In General Formula (1), R ₁ represents a hydrogen atom or a substituent. J represents —CO—, —COO—, —CONR ¹⁰ —, —OCO—, a methylene group, a phenylene group, or —C ₆ H _4. Represents a CO— group, R ¹⁰ represents a hydrogen atom, an alkyl group, an aryl group, or an aralkyl group, W represents a single bond or a divalent linking group, and A ₁ represents a heterocyclic group.)
(In General Formula (2), R _{2 to} R ₅ each independently represents a single bond, a hydrogen atom, or a substituent with W. Q ₁ is an atomic group necessary for forming a ring together with a carbon atom. _.R 1 representing a, J, and W have the same meanings as _R 1, J, and W in the general formula (1).)
(In General Formula (3), R _{6 to} R ₈ each independently represents a hydrogen atom or a substituent. X represents an anionic group that balances the cation charge on nitrogen. R ₁ , J, and W represent the general formula. (It represents the same meaning as R ₁ , J, and W in (1).)
(In the general formula (4), R ₉ represents a hydrogen atom or a substituent. Q ₂ represents an atomic group necessary for forming an unsaturated ring together with a carbon atom and a nitrogen atom. R ₁ , J , And W represent the same meaning as R ₁ , J, and W in the general formula (1).