JP2019038890A - Colorant dispersion, method for producing colorant dispersion and ink for inkjet recording - Google Patents

Abstract

To provide a colorant dispersion which is suitably used for a low liquid absorbing recording medium, and is excellent in dispersion stability and printability even when a solvent having high permeability and a solvent having a high boiling point coexist, and to provide a method for producing the colorant dispersion and ink for inkjet recording.SOLUTION: A colorant dispersion contains colorant particles, a basic compound, a crosslinking agent and water, where the colorant particles are colorant particles in which an unneutralized resin having an alkyleneoxy group having 1 to 6 carbon atoms and a carboxyl group is adsorbed onto the surface of the colorant, and an amount of adsorption (unneutralized resin adsorption ratio) of the unneutralized resin to the colorant in the colorant particles is 30 mass% or more.SELECTED DRAWING: None

Description

  The present invention relates to a colorant dispersion that is excellent in dispersion stability and printability even when a solvent having a high permeability and a solvent having a high boiling point coexist, a method for producing the colorant dispersion, and an ink for inkjet recording.

  The ink jet recording method is a recording method in which characters and images are obtained by ejecting ink droplets directly from a very fine nozzle onto a recording medium and attaching them. This method is easy to achieve in full color and is inexpensive, and has a widespread use because it has many advantages such as the ability to use plain paper as a recording medium and non-contact with the substrate, especially in terms of safety and environmental impact. Water-based ink has become the mainstream because of its small amount.

  Under these circumstances, in recent years, there is a need for printing on a recording medium for commercial printing using a low liquid-absorbing coated paper or a film of a non-liquid-absorbing resin such as a polyvinyl chloride resin, a polypropylene resin, or a polyester resin. It is growing. Generally, the drying mechanism after the water-based ink has landed on the substrate is classified into penetration into the substrate and evaporation, and it is known that the contribution of penetration is very large. Therefore, low-water-absorbent coated paper or films of non-liquid-absorbing resins such as polyvinyl chloride resin, polypropylene resin, and polyester resin have a slow penetration of water-based ink. It was difficult to perform the printing used well. In addition, water-based inks need to be added with a water-soluble solvent having a high boiling point and high solubility in water for the purpose of preventing the drying of the nozzle. There was a problem that the printing speed was remarkably lowered due to poor properties.

  In order to solve these problems, a method of adding a water-soluble solvent having high permeability and high boiling point to the ink to improve the drying property of the ink can be considered. For example, Patent Document 1 discloses an aqueous ink containing a polysiloxane surfactant and an organic solvent having a specific boiling point and surface tension.

  Patent Document 2 discloses an aqueous ink in which a water-insoluble polymer containing a hydrophilic monomer having a specific structure and an organic solvent having a specific boiling point are combined.

  However, the techniques described in Patent Document 1 and Patent Document 2 are limited in the water-soluble solvent to be used, and have a problem in designing an ink that can satisfy various required characteristics in recent years. Further, depending on the colorant and solvent type used, the dispersion stability and printability were insufficient. That is, it is desired to provide a colorant dispersion, a method for producing a colorant dispersion, and an ink for inkjet recording, which are more excellent in dispersion stability and printability even when a solvent having a high permeability and a solvent having a high boiling point coexist. It was rare.

JP 2014-205768 A JP 2014-139298 A

  An object of the present invention is to provide a colorant dispersion that is suitably used for a low liquid-absorbing recording medium and has excellent dispersion stability and printability even when a solvent having a high permeability and a solvent having a high boiling point coexist. Is to provide. Moreover, it is providing the manufacturing method of this coloring agent dispersion, and the ink for inkjet recording.

The above object is achieved by the present invention described below.
That is, the present invention is a colorant dispersion containing colorant particles, a basic compound, a crosslinking agent and water, wherein the colorant particles have an alkyleneoxy group having 1 to 6 carbon atoms and a carboxyl group. The neutralized resin is adsorbed on the surface of the colorant, and the colorant particle is a colorant particle having an adsorption amount of the unneutralized resin to the colorant in the colorant particle (an unneutralized resin adsorption rate) of 30% by mass or more Agent dispersion.

  The present invention also relates to the colorant dispersion, wherein the weight-average molecular weight of the unneutralized resin having an alkyleneoxy group having 1 to 6 carbon atoms and a carboxyl group is 5,000 to 15,000.

  The present invention also relates to the above colorant dispersion, wherein the volume median diameter by dynamic light scattering is 20 to 100 nm.

  The present invention also relates to the colorant dispersion, wherein the acid value of the unneutralized resin having an alkyleneoxy group having 1 to 6 carbon atoms and a carboxyl group is 120 to 300 mgKOH / g.

  The present invention also relates to the above colorant dispersion, wherein the crosslinking agent contains at least one group selected from the group consisting of an aziridine group, a carbodiimide group and an epoxy group.

  Moreover, this invention relates to the said colorant dispersion whose unneutralized resin adsorption rate is 60 mass% or more.

  The present invention also relates to the colorant dispersion described above, which is used for a stationery colorant, a paint colorant, a printing ink colorant, an electrophotographic colorant, an ink jet recording ink colorant, or a textile colorant. .

  The present invention also includes a step of kneading and refining a mixture containing a colorant, an unoxygenated resin having an alkyleneoxy group having 1 to 6 carbon atoms, and a carboxyl group, a water-soluble inorganic salt, and a water-soluble organic solvent. Removing the water-soluble inorganic salt and the water-soluble organic solvent, adding a basic compound and water to neutralize the carboxyl group of the unneutralized resin, adding a crosslinking agent, The present invention relates to a method for producing a colorant dispersion, wherein the step of crosslinking the neutralized resin is sequentially performed.

  Furthermore, this invention relates to the ink for inkjet recording containing the said colorant dispersion.

  According to the present invention, a colorant dispersion having excellent dispersion stability and printability even when a solvent having a high permeability and a solvent having a high boiling point coexist, a method for producing a colorant dispersion, and an ink for inkjet recording Is provided.

  Hereinafter, preferred embodiments will be described to describe the colorant dispersion of the present invention, a method for producing the same, and an ink jet recording ink using the same. The colorant dispersion of the present invention is a colorant dispersion containing at least colorant particles, a basic compound, a crosslinking agent, and water, wherein the colorant particles are an alkyleneoxy group having 1 to 6 carbon atoms and a carboxyl. It is a colorant dispersion in which the unneutralized resin having a group is a colorant particle adsorbed on the colorant surface, and the unneutralized resin adsorption rate is 30% by mass or more.

  The colorant dispersion of the present invention has an effect of being more excellent in dispersion stability and printability even when a solvent having a high permeability and a solvent having a high boiling point coexist. The reason is not clear, but it is thought as follows. When the unneutralized resin adsorption rate is 30% by mass or more, the unneutralized resin is effectively adsorbed on the colorant, and further, the colorant can be coated more firmly by reacting with the crosslinking agent. . This makes it possible to provide a stable dispersion even when a highly permeable solvent and a solvent having a high boiling point coexist. In addition, since there are few unadsorbed dispersion resins in the dispersion, thickening due to the reaction between the unadsorbed dispersant and the cross-linking agent is suppressed, and the stability over time is excellent. And printability can be achieved.

Hereinafter, each component used in the present invention will be described.
<Colorant particles>
In the colorant particle of the present invention, an unneutralized resin having an alkyleneoxy group having 1 to 6 carbon atoms and a carboxyl group is adsorbed on the surface of the colorant, and the unneutralized resin adsorption rate is 30% by mass or more. It is characterized by being. By using a non-neutralized resin having a higher hydrophobicity than the neutralized resin, the amount of adsorption to the colorant can be dramatically improved, and the colorant particles sufficiently coated with the colorant can be obtained. it can. Thereby, the dispersion stability is greatly improved. On the other hand, the neutralizing resin cannot sufficiently coat the colorant, and colorant particles having excellent dispersion stability cannot be obtained.

[Production of colorant particles]
Specifically, the colorant particles of the present invention are preferably obtained by sequentially performing the following step (1) and step (2).
Step (1): A step of kneading and refining a mixture containing a colorant, an unneutralized resin having a C 1-6 alkyleneoxy group and a carboxyl group, a water-soluble inorganic salt and a water-soluble organic solvent.
Step (2): A step of removing the water-soluble inorganic salt and the water-soluble organic solvent.

The method for refining the colorant in step (1) is not particularly limited, and any method can be applied, but a milling and kneading step by salt milling is suitable.
For example, a mixture containing at least a colorant, an unneutralized resin, a water-soluble inorganic salt, and a water-soluble organic solvent is used as a kneader, a two-roll mill, a three-roll mill, a ball mill, an attritor, a horizontal sand mill, a vertical sand mill, and / or Grinding and kneading can be performed using a kneader such as an annular type bead mill. In addition, the processing conditions and the like can be appropriately adjusted according to the type of the colorant, the required degree of refinement, and the like, and it is preferable to perform heating when mechanically kneading. Among these kneading and kneading methods, it is preferable to use a kneader in order to dramatically improve the amount of adsorption of the unneutralized resin to the colorant.

  The water-soluble inorganic salt works as a crushing aid, and crushes the colorant using the high hardness of the water-soluble inorganic salt. The water-soluble inorganic salt used in the milling and kneading method is not limited as long as it is an inorganic salt exhibiting water-solubility as its name does not depart from the gist of the present invention. Preferred examples include sodium chloride, barium chloride, potassium chloride, sodium sulfate and the like. It is preferable to use sodium chloride (salt) from the viewpoint of price.

The water-soluble organic solvent used in the milling and kneading method serves to wet the colorant and water-soluble inorganic salt, dissolves (mixes) in water, and does not substantially dissolve the water-soluble inorganic salt used. It needs to be a thing. Furthermore, it should have a moderate affinity with the unneutralized resin.
Examples of such a water-soluble organic solvent include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycol, and polypropylene glycol; butanediol, pentanediol, hexanediol, and the like Diols such as diols; glycol esters such as propylene glycol laurate; ethers of diethylene glycol monoethyl, diethylene glycol monobutyl, diethylene glycol monohexyl, cellosolve including propylene glycol ether, dipropylene glycol ether, and triethylene glycol ether Glycol ethers: methanol, ethanol, isopropyl alcohol Alcohols, such as alcohol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, butyl alcohol, pentyl alcohol, and alcohols similar thereto; or sulfolane; lactones such as γ-butyrolactone; N- Examples include lactams such as (2-hydroxyethyl) pyrrolidone; various other solvents known as water-soluble organic solvents such as glycerin and derivatives thereof. These water-soluble organic solvents can be used alone or in combination.
Among them, polyhydric alcohols having a high boiling point and low volatility and high surface tension are preferable, and glycols such as diethylene glycol and triethylene glycol are particularly preferable.

  The amount of the water-soluble organic solvent to be added is not particularly limited, but is preferably 5 to 1,000 parts by mass, more preferably 50 to 500 parts by mass with respect to 100 parts by mass of the colorant. The water-soluble inorganic salt is preferably used in an amount of 50 to 2,000 parts by mass, more preferably 300 to 1,000 parts by mass with respect to 100 parts by mass of the colorant, from the viewpoint of both processing efficiency and production efficiency. The unneutralized resin is preferably used in an amount of 5 to 100 parts by mass, more preferably 10 to 80 parts by mass with respect to 100 parts by mass of the colorant in terms of solid content, from the viewpoint of printing density and storage stability.

  In the step (2), for example, after the step (1) is performed, a mixture containing a colorant is taken out from the grinding kneader, and ion-exchanged water is added thereto to perform stirring to obtain a suspension. The amount of water to be added is not particularly limited as long as it is sufficient to obtain a suspension. You may heat as needed. For example, water having a weight of 10 to 10,000 times the weight of step (1) is added and mixed and stirred. Although the mixing stirring conditions at this time are not specifically limited, It is preferable to carry out at the temperature of 25-90 degreeC. Next, by removing the filtrate by an operation such as filtration, the water-soluble organic solvent and water-soluble inorganic salt used in the milling kneader can be removed, and the colorant is coated with an unneutralized resin. Colorant particles can be obtained. Strictly speaking, since the colorant particles contain ion-exchanged water, a step of further removing water may be performed. Although it will not be limited if it is the method of removing water, The method of performing a drying process can be mentioned as a suitable method. Examples of drying conditions include a method of drying for 12 to 48 hours at 80 to 120 ° C. under normal pressure, and a method of drying for 12 to 60 hours at 25 to 80 ° C. under reduced pressure. It can be illustrated. Although a drying process is not specifically limited, The method using a spray drying apparatus can also be illustrated. A pulverization process may be performed simultaneously with the drying process or after the drying process.

  The content of the colorant particles in the colorant dispersion is preferably 5 to 40% by mass, more preferably 10 to 30% by mass or less from the viewpoint of printing density and storage stability. The volume median diameter of the colorant particles is preferably 20 to 100 nm, more preferably 25 to 95 nm, and most preferably 30 to 90 nm from the viewpoint of preventing clogging of the nozzles of the printer and storage stability. The volume median diameter is measured using a laser diffraction / scattering method.

[Unneutralized resin adsorption amount]
The unneutralized resin adsorption rate to the surface of the colorant particles is 30% by mass or more from the viewpoint of dispersion stability when a solvent having a high permeability and a solvent having a high boiling point are added. When the unneutralized resin adsorption rate is less than 30% by mass, the adsorption and coating of the unneutralized resin on the surface of the colorant are insufficient, and the unneutralized resin adsorbed on the colorant and the below-mentioned crosslinking agent The reaction does not proceed effectively, and the dispersion stability of the colorant dispersion deteriorates. In addition, the cross-linking reaction with the non-adsorbed unneutralized resin proceeds, and the stability over time also deteriorates.
The unneutralized resin adsorption rate is preferably 45% by mass or more, and particularly preferably 60% by mass or more. In addition, the measuring method of unneutralized resin adsorption rate is described in detail in Examples.

<Colorant>
There are no particular restrictions on the colorant for obtaining the colorant particles, and pigments, hydrophobic dyes, water-soluble dyes (acidic dyes, reactive dyes, direct dyes, etc.) can be used, but water resistance and storage stability. From the viewpoint of scratch resistance, pigments and hydrophobic dyes are preferred. The pigment may be either an inorganic pigment or an organic pigment. If necessary, they can be used in combination with extender pigments (silica, calcium carbonate, talc, etc.). Examples of the inorganic pigment include carbon black, metal oxide, metal sulfide, and metal chloride. Of these, carbon black is preferred particularly for black aqueous inks. Examples of carbon black include furnace black, thermal lamp black, acetylene black, and channel black. Examples of the organic pigment include azo pigments, diazo pigments, phthalocyanine pigments, quinacridone pigments, isoindolinone pigments, dioxazine pigments, perylene pigments, perinone pigments, thioindigo pigments, anthoraquinone pigments, and quinophthalone pigments.

Specifically, for example,
C. I. Pigment Red 1, 2, 3, 4, 5, 6, 7, 9, 10, 14, 17, 22, 23, 31, 32, 38, 41, 48: 1, 48: 2, 48: 3, 48: 4, 49, 49: 1, 49: 2, 52: 1, 52: 2, 53: 1, 57: 1, 60: 1, 63: 1, 66, 67, 81: 1, 81: 2, 81: 3, 83, 88, 90, 105, 112, 119, 122, 123, 144, 146, 147, 148, 149, 150, 155, 166, 168, 169, 170, 171, 172, 175, 176, 177, 178, 179, 184, 185, 187, 188, 190, 200, 202, 206, 207, 208, 209, 210, 216, 220, 224, 226, 242, 246, 254, 255, 264, 266, 269, 270 272,279,
C. I. Pigment Yellow 1, 2, 3, 4, 5, 6, 10, 11, 12, 13, 14, 15, 16, 17, 18, 20, 24, 31, 32, 34, 35, 35: 1, 36, 36: 1, 37, 37: 1, 40, 42, 43, 53, 55, 60, 61, 62, 63, 65, 73, 74, 77, 81, 83, 86, 93, 94, 95, 97, 98, 100, 101, 104, 106, 108, 109, 110, 113, 114, 115, 116, 117, 118, 119, 120, 123, 125, 126, 127, 128, 129, 137, 138, 139, 147, 148, 150, 151, 152, 153, 154, 155, 156, 161, 162, 164, 166, 167, 168, 169, 170, 171, 172, 173, 17 , 175,176,177,179,180,181,182,185,187,188,193,194,199,213,214, C. I. Pigment Orange 2, 5, 13, 16, 17: 1, 31, 34,
36, 38, 43, 46, 48, 49, 51, 52, 55, 59, 60, 61, 62, 64, 71, 73,
C. I. Pigment Green 7, 10, 36, 37, 58, 59, 62, 63,
C. I. Pigment Blue 1, 2, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 22, 60, 64, 66, 79, 79, 80
C. I. Pigment Violet 1, 19, 23, 27, 32, 37, 42C. I. Pigment Brown 25, 28
C. I. Pigment Black 1, 7 and the like.

Among these, the pigments that can be preferably used include the following.
C. I. Pigment Red 48: 1, 48: 2, 48: 3, 48: 4, 57: 1, 122,146, 147, 148, 150, 170, 176, 177, 184, 185, 242, 254, 255, 264, 266, 269,
C. I. Pigment Yellow 12, 13, 14, 17, 74, 83, 108, 109, 120, 150, 151, 154, 155, 180, 185, 213
C. I. Pigment Orange 36, 38, 43, 64
C. I. Pigment Green 7, 36, 37, 58, 62, 63,
C. I. Pigment Blue 15: 1, 15: 3, 15: 6, 16, 22, 60, 66,
C. I. Pigment Violet 19, 23, 32,
C. I. Pigment Brown 25,
C. I. Pigment Black 1, 7
With these pigments, sufficient color reproducibility and / or light resistance as ink for inkjet recording can be maintained. However, the present invention is not limited to these.

  The average primary particle diameter of the pigment to be refined may vary depending on the application, but is usually 5 to 1,000 nm. As the pigment used here, an untreated crude pigment is usually used, but a pigment that has undergone some processing step may be used. The pigment used may be a single type or a plurality of types.

<Non-neutralized resin having an alkyleneoxy group having 1 to 6 carbon atoms and a carboxyl group>
The non-neutralized resin having an alkyleneoxy group having 1 to 6 carbon atoms and a carboxyl group only needs to have an alkyleneoxy group having 1 to 6 carbon atoms and a carboxyl group. A copolymer of an alkyleneoxy group-containing monomer having 1 to 6 carbon atoms and a carboxyl group-containing monomer is preferable, and these (meth) acrylate copolymers are more preferable.

[Alkyleneoxy group-containing monomer having 1 to 6 carbon atoms]
The alkyleneoxy group-containing monomer having 1 to 6 carbon atoms that is preferably used in the present invention (hereinafter referred to as monomer A) is specifically represented by the following general formula (1). Those are preferred. These lower the viscosity of the ink when the solvent is volatilized, improve the printability on a low liquid-absorbing substrate, and improve the storage stability and ejection properties of the colorant dispersion and ink jet recording ink using the same. effective.

［一般式（１）中、Ｒ^１は水素原子又はメチル基を示し、Ｒ^２は炭素数１〜６のアルキレン基を示し、Ｒ^３は水素原子、炭素数１以上２０以下のアルキル基又は水素原子が炭素数１以上９以下のアルキル基で置換されていてもよいフェニル基を示し、ｍはアルキレンオキシ基の平均付加モル数を示し、１以上１００以下の数である。］ General formula (1)

[In General Formula (1), R ¹ represents a hydrogen atom or a methyl group, R ² represents an alkylene group having 1 to 6 carbon atoms, R ³ represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or hydrogen. An atom represents a phenyl group which may be substituted with an alkyl group having 1 to 9 carbon atoms, m represents an average added mole number of an alkyleneoxy group, and is a number of 1 to 100. ]

In the general formula (1), R ¹ is a hydrogen atom or a methyl group, and a methyl group is preferable from the viewpoint of improving the dispersion stability of the colorant dispersion and the storage stability of the ink for ink jet recording using the same. . R ² is an alkylene group having 1 to 6 carbon atoms, and the alkyleneoxy group of —R ² —O— contributes to an improvement in affinity with water and a water-soluble solvent in the ink of the unneutralized resin. In the colorant dispersion, the alkyleneoxy group spreads in the ink and acts as a steric hindrance group, contributing to stabilization of the colorant dispersion. From an industrial viewpoint, an ethyleneoxy group is particularly preferable. R ³ is a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or a phenyl group in which a hydrogen atom may be substituted with an alkyl group having 1 to 9 carbon atoms, and the dispersion stability of the colorant dispersion and From the viewpoint of improving the storage stability of an ink for inkjet recording using a hydrogen atom, an alkyl group having 1 to 20 carbon atoms is preferable, an alkyl group having 1 to 3 carbon atoms is more preferable, and a methyl group is still more preferable. .

  In the general formula (1), m is 1 or more and 100 or less. m is preferably 4 or more, more preferably 9 or more from the viewpoint of lowering the viscosity of the ink at the time of solvent volatilization, improving the printability on a highly hydrophobic substrate, and improving the storage stability and ejection properties of the pigment ink. preferable. Further, m is preferably 70 or less, and more preferably 40 or less. Further, m in the range of 9 to 40 is preferable because the colorant dispersion and the dispersion stability during production of the ink for ink jet recording using the same are improved.

  Preferable examples of the monomer represented by the general formula (1) include polyethylene glycol mono (meth) acrylate, methoxypolyethylene glycol mono (meth) acrylate, octoxypolyethylene glycol mono (meth) acrylate, and stearoxypolyethylene glycol mono One or more selected from (meth) acrylates may be mentioned, and methoxypolyethylene glycol monomethacrylate is most preferable from the above viewpoint. Specific examples of commercially available monomers of the general formula (1) include Blemmer PME100, PME400, and PME1000 (manufactured by NOF Corporation).

[Carboxyl group-containing monomer]
Specific examples of the carboxyl group-containing monomer (hereinafter referred to as “monomer B”) preferably used in the present invention include maleic acid, fumaric acid, itaconic acid, citraconic acid, or alkyl or their Alkenyl monoester, phthalic acid β- (meth) acryloxyethyl monoester, isophthalic acid β- (meth) acryloxyethyl monoester, terephthalic acid β- (meth) acryloxyethyl monoester, succinic acid β- (meth) Examples include acryloxyethyl monoester, acrylic acid, methacrylic acid, crotonic acid, and cinnamic acid. In order to further improve the storage stability, a carboxyl group-containing (meth) acrylate is preferable, and among these, it is more preferable to include acrylic acid or methacrylic acid. By having a carboxyl group, an unneutralized resin adsorbed on the colorant can obtain an effect of charge repulsion when neutralized and ionized with a basic compound or the like. Charge repulsion occurs and the dispersion stability of the colorant dispersion is improved.

[Other monomers]
The unneutralized resin may contain other monomers other than the alkyleneoxy group-containing monomer having 1 to 6 carbon atoms and the carboxyl group-containing monomer in the polymerization composition. Other monomers include alkyl-based ethylenically unsaturated monomers, hydroxyl group-containing ethylenically unsaturated monomers, nitrogen-containing ethylenically unsaturated monomers, aromatic ring group-containing ethylenically unsaturated monomers, etc. There is. A specific example will be described below.

(Alkyl ethylenically unsaturated monomer)
Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, decyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl ( Examples include meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, and behenyl (meth) acrylate.

(Hydroxyl-containing ethylenically unsaturated monomer)
Examples of the hydroxyl group-containing ethylenically unsaturated monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, glycerol mono (meth) acrylate, and 4-hydroxyvinyl. Examples include benzene.

(Nitrogen-containing ethylenically unsaturated monomer)
Nitrogen-containing ethylenically unsaturated monomers include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, methylethylaminoethyl (meth) acrylate, dimethylaminostyrene, diethylaminostyrene, (meth) acrylamide, N- Monoalkylol (meth) acrylamide such as methylol (meth) acrylamide, N-methoxymethyl- (meth) acrylamide, N 2, N-di (methylol) acrylamide, N-methylol-N-methoxymethyl (meth) acrylamide, N 2, N-di (methoxymethyl) acrylamide etc. are mentioned.

(Aromatic ring group-containing ethylenically unsaturated monomer)
Examples of the aromatic ring group-containing ethylenically unsaturated monomer include styrene, α-methylstyrene, 2-methylstyrene, chlorostyrene, benzyl (meth) acrylate, vinylnaphthalene, vinylcarbazole and the like.

  By including the aromatic ring group-containing ethylenically unsaturated monomer in the non-neutralized resin, the non-neutralized resin can obtain a high affinity for the pigment by π-electron interaction. It is possible to form a good adsorption state. From such a viewpoint, the unneutralized resin preferably contains an aromatic ring group-containing ethylenically unsaturated monomer, and particularly preferably contains benzyl (meth) acrylate.

  As the amount of each monomer in the unneutralized resin, the content of the structural unit derived from the monomer A in the unneutralized resin is 5 to 50 mass from the viewpoint of the printability of the resulting ink for inkjet recording. % Is preferable, 5 to 40% by mass is more preferable, and 5 to 30% by mass is most preferable. The content of the structural unit derived from the monomer B in the unneutralized resin is preferably 5 to 50% by mass, more preferably 5 to 40% by mass from the viewpoint of storage stability of the resulting colorant dispersion. 5-30 mass% is the most preferable. Moreover, it is preferable that 40 mass% or more of aromatic group containing ethylenically unsaturated monomers are included from a viewpoint of raising the adsorption rate to the coloring agent of unneutralized resin.

  The unneutralized resin of the present invention preferably has a weight average molecular weight in the range of 2,000 to 70,000, more preferably a weight average molecular weight in the range of 3,000 to 50,000, The weight average molecular weight is more preferably in the range of 5,000 to 20,000, and particularly preferably in the range of 5,000 to 15,000. If the weight average molecular weight of the unneutralized resin is less than 2,000, the interaction with the pigment is lowered, and a sufficient amount of adsorption to the colorant cannot be obtained, resulting in a decrease in dispersion stability. Moreover, when the weight average molecular weight of unneutralized resin is larger than 70,000, the viscosity of the colorant dispersion tends to increase.

  Further, the unneutralized resin of the present invention has an acid value, and the range thereof is preferably in the range of 50 to 400 mgKOH / g, more preferably in the range of 100 to 350 mgKOH / g, and 120 to A range of 300 mgKOH / g is more preferable, and a range of 120 to 200 mgKOH / g is particularly preferable. When the acid value of the unneutralized resin is lower than 50 mgKOH / g, the dispersion stability of the colorant dispersion is lowered, and the ejection stability of the ink for ink jet recording tends to deteriorate. On the other hand, when the acid value is higher than 400 mgKOH / g, the adsorptive power of the unneutralized resin to the pigment surface is lowered, and the storage stability of the colorant dispersion tends to be lowered. In addition, the weight average molecular weight and acid value of the unneutralized resin in this invention can be measured by the method shown in an Example.

Next, the manufacturing method of unneutralized resin is demonstrated.
The unneutralized resin is produced by copolymerizing the monomer mixture described above by a known polymerization method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, or an emulsion polymerization method. Among these polymerization methods, the solution polymerization method is preferable. The solvent used in the solution polymerization method is not particularly limited, but a polar organic solvent is preferable. When the polar organic solvent is miscible with water, it can be used by mixing with water. Examples of the polar organic solvent include aliphatic alcohols having 1 to 3 carbon atoms such as methanol, ethanol and propanol; ketones such as acetone and methyl ethyl ketone; esters such as ethyl acetate and the like. Among these, diethylene glycol, methanol, ethanol, 1-butanol, acetone, methyl ethyl ketone, or a mixed solvent of at least one of these with water is preferable. As will be described later, in the present invention, it is preferable to obtain the colorant particles by the milling and kneading method. It is preferable not to contain. In the polymerization, azo compounds such as 2,2′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), t-butyl peroxyoctate, dibenzoyl oxide, etc. Known radical polymerization initiators such as organic peroxides can be used. The amount of the radical polymerization initiator is preferably 0.001 to 5 mol, more preferably 0.01 to 2 mol, per mol of the monomer mixture. In the polymerization, a known polymerization chain transfer agent such as mercaptans such as octyl mercaptan and 2-mercaptoethanol and thiuram disulfide may be further added.

  Since the polymerization conditions for the unneutralized resin vary depending on the type of polymerization initiator, monomer, and solvent used, it cannot be determined unconditionally. Usually, the polymerization temperature is preferably 30 to 150 ° C., more preferably 50 to 130 ° C., and the polymerization time is preferably 1 to 20 hours. The polymerization atmosphere is preferably a nitrogen gas atmosphere or an inert gas atmosphere such as argon. After completion of the polymerization reaction, the produced non-neutralized resin can be isolated from the reaction solution by a known method such as reprecipitation or solvent distillation, if necessary. Further, the obtained unneutralized resin can be purified by repeating reprecipitation or removing unreacted monomers by membrane separation, chromatographic methods, extraction methods, and the like.

  The unneutralized resin having an alkyleneoxy group having 1 to 6 carbon atoms and a carboxyl group of the present invention may be used alone or in combination with another unneutralized resin. The unneutralized resin used in combination preferably has a carboxyl group, and examples thereof include acrylic resins, styrene acrylic resins, maleic resins, styrene maleic resins, α-olefin maleic resins, urethane resins, and ester resins. Especially, it is preferable to use alpha olefin maleic acid resin together. By using a highly hydrophobic α-olefin maleic resin together, the amount of resin adsorbed to the colorant is improved, and the dispersion stability of the colorant dispersion and the ink for inkjet recording is improved.

<Basic compound>
The colorant dispersion of the present invention can stabilize the dispersion of the colorant particles by ionizing the carboxyl group of the unneutralized resin. For this reason, it is preferable that the colorant dispersion and the ink for ink jet recording using the same are adjusted to be neutral or alkaline. However, if the alkalinity is too strong, it may cause corrosion of various members used in the ink jet recording apparatus. Therefore, the pH range is preferably 7 to 10. Examples of the pH adjuster used at this time include the following. For example, inorganic alkaline agents such as ammonia water, various organic amines such as dimethylaminoethanol, diethanolamine, and triethanolamine, alkali metal hydroxides such as sodium hydroxide, lithium hydroxide, and potassium hydroxide, organic acids and mineral acids Etc. can be used. By ionizing the non-neutralized resin of the colorant particles described later, the colorant particles are neutralized and dispersed or dissolved in the aqueous liquid medium.

The degree of neutralization of the unneutralized resin is preferably 10 to 100 mol%, more preferably 30 to 100 mol%, and more preferably 50 to 100 mol% from the viewpoint of storage stability of the colorant dispersion. It is particularly preferred that Here, the neutralization degree can be obtained by the following equation.
{[Weight of basic compound (g) / equivalent of basic compound] / [acid value of unneutralized resin (KOH mg / g) × weight of unneutralized resin (g) / (56 × 1000)]} × 100

<Crosslinking agent>
In the present invention, a compound having a reactive functional group capable of reacting with two or more carboxyl groups in the molecule is preferably used in order to appropriately crosslink the unneutralized resin. The reactive functional group is preferably at least one selected from the group consisting of an isocyanate group, an aziridine group, a carbodiimide group, an oxetane group, an oxazoline group and an epoxy group, more preferably an aziridine group, a carbodiimide group and an epoxy group. At least one selected from the group, particularly preferably an epoxy group.
The weight average molecular weight (Mw) of the crosslinking agent is preferably from 100 to 2,000, more preferably from 120 to 1,500, particularly preferably from 150 to 1,000, from the viewpoints of easy reaction and storage stability. . The number of reactive functional groups contained in the crosslinking agent is preferably 2 to 6 from the viewpoint of controlling the molecular weight of the unneutralized resin after crosslinking to improve storage stability.

Specific examples of the crosslinking agent used in the present invention include the following.
Compound having two or more isocyanate groups in the molecule: for example, organic polyisocyanate or isocyanate group-terminated prepolymer.
Examples of organic polyisocyanates include aliphatic diisocyanates such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate; aromatic diisocyanates such as tolylene-2,4-diisocyanate and phenylene diisocyanate; alicyclic diisocyanates; aromatic Triisocyanate; and modified products such as urethane modified products thereof. The isocyanate group-terminated prepolymer can be obtained by reacting an organic polyisocyanate or a modified product thereof with a low molecular weight polyol or the like.

  Compounds having two or more aziridine groups in the molecule: for example, N, N′-diphenylmethane-4,4′-bis (1-aziridinecarboxite), N, N′-toluene-2,4-bis (1 -Aziridinecarboxite), bisisophthaloyl-1- (2-methylaziridine), tri-1-aziridinylphosphine oxide, N, N'-hexamethylene-1,6-bis (1-aziridinecarboxite) 2,2′-bishydroxymethylbutanol-tris [3- (1-aziridinyl) propionate], trimethylolpropane tri-β-aziridinylpropionate, tetramethylolmethane tri-β-aziridinylpropionate , Tris-2,4,6- (1-aziridinyl) -1,3,5-triazine, 4,4′-bis (ethyleneiminocarbo Nylamino) diphenylmethane and the like.

  Compound having two or more carbodiimide groups in the molecule: for example, high molecular weight polycarbodiimide produced by decarboxylation condensation reaction of a diisocyanate compound in the presence of a carbodiimidization catalyst. Examples of such high molecular weight polycarbodiimides include Nisshinbo's Carbodilite series.

  Compounds having two or more oxetane groups in the molecule: for example, 4,4 ′-(3-ethyloxetane-3-ylmethyloxymethyl) biphenyl (OXBP), 3-ethyl-3-hydroxymethyloxetane (EHO) 1,4-bis [{(3-ethyl-3-oxetanyl) methoxy} methyl] benzene (XDO), di [1-ethyl (3-oxetanyl)] methyl ether (DOX), di [1-ethyl (3 -Oxetanyl)] methyl ether (DOE), 1,6-bis [(3-ethyl-3-oxetanyl) methoxy] hexane (HDB), 9,9-bis [2-methyl-4- {2- (3- Oxetanyl)} butoxyphenyl] fluorene, 9,9-bis [4- [2- {2- (3-oxetanyl)} butoxy] ethoxyphenyl] fluorene, and the like.

  Compound having two or more oxazoline groups in the molecule: For example, a compound in which two or more, preferably 2-3 oxazoline groups are bonded to an aliphatic group or an aromatic group, more specifically 2, 2′- Bisoxazoline compounds such as bis (2-oxazoline), 1,3-phenylenebisoxazoline, 1,3-benzobisoxazoline, and compounds having a terminal oxazoline group obtained by reacting the compound with a polybasic carboxylic acid.

  Compounds having two or more epoxy groups in the molecule: for example, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin triglycidyl ether, glycerol polyglycidyl ether, polyglycerol polyglycidyl ether, tri Polyglycidyl ethers such as methylolpropane polyglycidyl ether, sorbitol polyglycidyl ether, pentaerythritol polyglycidyl ether, resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether, hydrogenated bisphenol A type diglycidyl ether.

  Among these, compounds having two or more epoxy groups in the molecule are preferable, and ethylene glycol diglycidyl ether and trimethylolpropane polyglycidyl ether are particularly preferable.

  The crosslinking agent is preferably moderately water-soluble from the viewpoint of efficiently reacting with the carboxyl group of the unneutralized resin in water. For example, when the crosslinking agent is dissolved in 100 g of water at 25 ° C., the amount of the crosslinking agent dissolved Is preferably 0.1 to 50 g, more preferably 0.2 to 40 g, and still more preferably 0.5 to 30 g.

  The addition amount of the crosslinking agent is preferably an amount for reacting 10 to 100 mol% of the carboxyl group of the unneutralized resin. Among these, it is more preferable to add an amount of 30 to 100 mol%, and it is preferable to add an amount of 30 to 90 mol%.

<Colorant dispersion>
The colorant dispersion of the present invention contains at least colorant particles, a basic compound, a crosslinking agent and water. As a method for producing these colorant dispersions, it is preferable to sequentially perform the following step (3) and step (4) from the viewpoint of storage stability of the colorant dispersion.
Step (3): Colorant particles, a basic compound and water are added to neutralize the carboxyl group of the unneutralized resin Step (4): a crosslinking agent is added to crosslink with the unneutralized resin In the step of neutralizing the carboxyl group of the process unneutralized resin and the step of adding a crosslinking agent to crosslink the unneutralized resin, the temperature and time can be appropriately selected and determined. The time for the neutralization step is preferably 0. The temperature of the neutralization step is preferably 40 to 95 ° C. for 5 to 10 hours, more preferably 1 to 5 hours. The time for the crosslinking step is preferably 0. 5 to 10 hours, more preferably 1 to 5 hours, the temperature of the crosslinking step is preferably 40 to 95 ° C

  From the viewpoint of storage stability, the content of water in the colorant dispersion is preferably 30 to 85% by mass, and more preferably 30 to 80% by mass. As water, it is preferable to use ion-exchanged water (deionized water) instead of general water containing various ions. Hereinafter, unless otherwise specified, water refers to ion-exchanged water.

<Ink for inkjet recording>
Next, the case where the ink for inkjet recording is formed using the colorant dispersion of the present invention will be described. The ink for ink jet recording contains a water-soluble solvent used by mixing with water in order to impart printability. As these solvents, glycol ethers and diols are good, and (poly) alkylene glycol monoalkyl ethers and alkanediols having 3 to 6 carbon atoms are particularly effective. These solvents penetrate very rapidly into the substrate, and penetrate quickly into low-absorbent substrates such as coated paper, art paper, vinyl chloride sheets, and films. Therefore, drying at the time of printing is fast and accurate printing can be realized. Moreover, since the boiling point is high, the function as a wetting agent is sufficient.

Specific examples of glycol ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monopentyl ether, diethylene glycol monohexyl ether, triethylene Glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monobutyl ether, propylene glycol monopropyl ether, propylene Glycol monobutyl ether, dipropylene glycol monomethyl ether, tripropylene glycol monomethyl ether, and the like.
Specific examples of diols include 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,2-pentanediol, 1,5-pentanediol, Examples include 1,2-hexanediol, 1,6-hexanediol, and 2-methyl-2,4-pentanediol.

  Of these, the most effective are diethylene glycol monobutyl ether, diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1,2-hexanediol. 2-methyl-2,4-pentanediol. These solvents may be used alone or in combination.

  Further, depending on the type of substrate to be printed, water-soluble nitrogen-containing complex such as 2-pyrrolidone, N-methylpyrrolidone, N-ethylpyrrolidone, N-methyloxazolidinone, N-ethyloxazolidinone and the like is used for the purpose of improving its solubility Ring compounds can also be added.

  In general, the content of the water-soluble organic solvent in the ink for ink jet recording is preferably 3 to 60% by mass, more preferably 3 to 50% by mass, based on the total weight of the ink. Further, the water content is preferably 10 to 90% by mass, more preferably 30 to 80% by mass, based on the total weight of the ink.

  Furthermore, the ink for inkjet recording using the colorant dispersion of the present invention preferably contains an aqueous emulsion. By containing an aqueous emulsion, the viscosity of the coated film can be improved without significantly increasing the viscosity. Thereby, water resistance, solvent resistance, scratch resistance and the like are improved. Even if a water-soluble resin is added, the resistance can be expected to improve to some extent, but the viscosity tends to increase. In the case of inkjet ink, there is a certain range in the viscosity at which ink can be ejected from the nozzles, and if the viscosity is too high, it may not be possible to eject ink, so it is important to suppress an increase in viscosity.

  The content of the aqueous emulsion as described above in the ink is a solid content in the range of 2% by mass to 30% by mass of the total weight of the ink, and more preferably 3% by mass to 20% by mass. It is a range. In addition, the ink for ink jet recording using the colorant dispersion of the present invention, in addition to the above-described components, may be a surfactant, an antifoaming agent, an antiseptic, in order to obtain an ink having desired physical properties as required. An additive such as an agent can be appropriately added. Examples of the amount of these additives added are preferably 0.05% by mass or more and 10% by mass or less, and more preferably 0.2% by mass or more and 5% by mass or less with respect to the total weight of the ink.

  The ink for ink jet recording thus produced can be suitably used for various ink jet printers. Applicable ink jet methods are not particularly limited, but examples include well-known on-demand types such as a charge control type, a continuous injection type such as a spray type, a piezo type, a thermal type, and an electrostatic suction type. Can do.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. In the following description, “parts” and “%” represent “parts by mass” and “% by mass”.

(Weight average molecular weight (Mw))
The weight average molecular weight (Mw) is a polystyrene measured using TSKgel column (manufactured by Tosoh Corporation) and GPC equipped with RI detector (manufactured by Tosoh Corporation, HLC-8320GPC) using THF as a developing solvent. It is a weight average molecular weight (Mw) in terms of conversion.

(Acid value)
About 1 g of a sample is accurately weighed in an Erlenmeyer flask and dissolved by adding 50 ml of a distilled water / dioxane (weight ratio: distilled water / dioxane = 1/9) mixture. With respect to the sample solution, a 0.1 mol / L potassium hydroxide / ethanol solution (titer a) was used by using a potentiometric measuring apparatus (manufactured by Kyoto Electronics Industry Co., Ltd., apparatus name “potentiometric automatic titrator AT-710M”). The amount of potassium hydroxide / ethanol solution (b (mL)) required until the end of titration was measured. The acid value (mgKOH / g) was determined by the following equation as the value of the resin in the dry state.
Acid value (mgKOH / g) = {(5.611 × a × F) / S} / (Nonvolatile content concentration / 100)
Where S: Amount of sample collected (g)
a: Consumption of 0.1 mol / L potassium hydroxide / ethanol solution (ml)
F: Potency of 0.1 mol / L potassium hydroxide / ethanol solution <Production of non-neutralized resin>
(Unneutralized resin P-1)
A reaction vessel equipped with a gas introduction tube, a thermometer, a condenser, and a stirrer was charged with 100 parts of diethylene glycol and replaced with nitrogen gas. The inside of the reaction vessel is heated to 110 ° C., monomer A-1 (in general formula (1), R ¹ = methyl group, R ² = ethylene group, R ³ = methyl group, m = 2 A mixture of 20 parts, 20 parts of acrylic acid, 60.0 parts of benzyl methacrylate, and 5.0 parts of perbutyl O (NOF Corporation) was dropped over 3 hours to carry out a polymerization reaction. After completion of dropping, the reaction was further carried out at 110 ° C. for 1 hour, 0.5 part of perbutyl O was added, and the reaction was further continued at 110 ° C. for 1 hour. Thereafter, it was confirmed that the conversion rate exceeded 98% by measuring the nonvolatile content, diethylene glycol was added, the nonvolatile content was adjusted to 30%, the reaction was terminated by cooling to room temperature, and the unneutralized resin solution P- 1 was obtained. The weight average molecular weight (Mw) of the unneutralized resin solution P-1 was about 13,000, and the acid value was 156 mgKOH / g.

(Unneutralized resins P-2 to P-14)
Except having changed into the raw material and preparation amount which were described in Table 1, it synthesize | combined like (P-1), and the unneutralized resin solution P-2 to P-14 was obtained. The molecular weight was adjusted appropriately by changing the amount of perbutyl O added. Each weight average molecular weight (Mw), non-volatile content, and acid value are as described in Table 1.

The abbreviations in Table 1 are shown below.
Monomer A-1: Monomer monomer A-2 in general formula (1) where R ¹ = methyl group, R ² = ethylene group, R ³ = methyl group, m = 2: General formula ( In 1), monomer monomer A-3 in which R ¹ = methyl group, R ² = ethylene group, R ³ = methyl group, m = 9: in general formula (1), R ¹ = methyl group, Monomer monomer A-4 where R ² = ethylene group, R ³ = methyl group, m = 23: In the general formula (1), R ¹ = hydrogen atom, R ² = propylene group, R ³ = methyl Group, monomer with m = 2

<Manufacture of colorant particles>
(Colorant particle B-1)
As a coloring agent, C.I. I. Pigment Red 122 (“FASTOGENSuperMagentaRG T” manufactured by DIC) (hereinafter referred to as PR122) 35.0 parts, sodium chloride 175.0 parts, P-1 as an unneutralized resin 12.25 parts as a solid content, water-soluble As a solvent, 6.4 parts of diethylene glycol was charged into a stainless steel gallon kneader (manufactured by Inoue Seisakusho) and kneaded at 80 ° C. for 3 hours. The mixture is added to 1,000 parts of water, stirred at a high speed mixer for about 1 hour while being heated to about 40 ° C. to form a slurry, filtered and washed repeatedly to remove sodium chloride and water-soluble organic solvent, and then reduce the pressure. The resultant was dried at 40 ° C. to obtain colorant particles B-1.

(Colorant particles B-2 to B-13, 15, 16)
Colorants B-2 to B-13, 15, and 16 were obtained in the same manner as the colorant particles B-1, except that the colorant to be used and the unneutralized resin were changed according to Table 2.

(Colorant particle B-14)
PR122 ("FASTOGENSuperMagentaRGT" manufactured by DIC) as a colorant, 175.0 parts sodium chloride, P-3 as an unneutralized resin, 6.125 parts in terms of solid content, Ceramer 1608 (manufactured by Baker Petrolite) : Non-acrylic resin, α-olefin-maleic anhydride copolymer and maleic anhydride monoester copolymer, acid value: 154 mg KOH / g, non-volatile content 100%) 6.125 parts in terms of solid content, As a water-soluble solvent and 6.4 parts of diethylene glycol were charged into a stainless steel gallon kneader (manufactured by Inoue Seisakusho) and kneaded at 80 ° C. for 3 hours. The mixture is added to 1,000 parts of water, stirred at a high speed mixer for about 1 hour while being heated to about 40 ° C. to form a slurry, filtered and washed repeatedly to remove sodium chloride and water-soluble organic solvent, and then reduce the pressure. The resultant was dried at 40 ° C. to obtain colorant particles B-14.

(Colorant particle B-17)
PR122 ("FASTOGENSuperMagentaRG T" manufactured by DIC) as a colorant, 175.0 parts of sodium chloride, P-3 as an unneutralized resin, 12.25 parts in terms of solid content, potassium hydroxide as a basic compound A stainless steel gallon kneader (manufactured by Inoue Seisakusho Co., Ltd.) was added in an amount of 19.11 parts so that the degree of neutralization was 100% from the acid value of the unneutralized resin used, and 6.4 parts of diethylene glycol as a water-soluble solvent. And kneaded at 80 ° C. for 3 hours. When this mixture was added to 1,000 parts of water and stirred with a high speed mixer for about 1 hour while being heated to about 40 ° C., it became a colorant dispersion and could not be obtained as colorant particles.

(Colorant particle B-18)
PR122 ("FASTOGENSuperMagentaRG T" manufactured by DIC) as a colorant, 175 parts in terms of solid content as P-3 as an unneutralized resin, and 10% aqueous solution of potassium hydroxide as a basic compound 273 parts from the acid value of the resin so that the neutralization degree is 100%, 200 parts of diethylene glycol as a water-soluble solvent are charged into a planetary mixer (manufactured by Inoue Seisakusho Co., Ltd.), the jacket temperature is heated to 80 ° C., and the speed is low. (Rotational speed: 10 rpm, revolution speed: 29.4 rpm). Thereafter, the speed was changed to a high speed (rotational speed: 20 rpm, revolution speed: 58.8 rpm), kneading was performed for 3 hours, the mixture was taken out and dried at 100 ° C. under reduced pressure to obtain colorant particles B-18.

<Evaluation of colorant particles>
(Measurement of unneutralized resin adsorption)
20 parts of the obtained colorant particles and a 10% aqueous solution of potassium hydroxide as a basic compound are added so that the neutralization degree becomes 100% from the acid value of the unneutralized resin used in the synthesis example of the colorant particles. Further, ion-exchanged water was added so that the nonvolatile content was 22%, and the mixture was stirred with a disper for 1 hour while being heated in an oil bath at 70 ° C. Thereafter, the mixture was cooled to room temperature, and then centrifuged at 100,000 rpm for 6 hours in an ultracentrifuge to precipitate the colorant particles. Thereafter, the supernatant was confirmed to be transparent, the supernatant was collected, the non-volatile content of the supernatant was measured, and the amount of unneutralized resin that had not been adsorbed (in the state ion-bonded with potassium ions) was calculated.
At this time, the unneutralized resin adsorbed on the colorant and coated with the colorant settles together with the colorant particles, and the unneutralized resin not adsorbed on the colorant is dissolved in the supernatant liquid. The resin adsorption amount was calculated according to the following formula. In addition, B-18 was measured in the same manner as the above procedure except that the basic compound was not added.
Unneutralized resin adsorption rate (%)
= (Initial unneutralized resin amount-supernatant unneutralized resin amount) × 100 / initial unneutralized resin amount

* Initial unneutralized resin amount: Colorant particle usage x Unneutralized resin to pigment ratio * Supernatant unneutralized resin amount: (Non-volatile content of supernatant x (total weight of test colorant dispersion-for test) Solid content of colorant dispersion)

Abbreviations in Table 2 are shown below.
PY180: C.I. I. Pigment Yellow 180, manufactured by Clariant Japan, "NOVOPERM Yellow P-HG"
Ceramer 1608: Non-acrylic resin, α-olefin-maleic anhydride copolymer and maleic anhydride monoester copolymer, acid value: 154 mg KOH / g, non-volatile content: 100% (manufactured by Baker Petrolite)

<Manufacture of colorant dispersion>
[Example 1]
(Colorant dispersion C-1)
20 parts of B-1 as colorant particles, 10% aqueous solution of potassium hydroxide as a basic compound, 10.92 parts, so that the degree of neutralization is 100% from the acid value of the unneutralized resin used, antiseptic PROXEL GXL (S) (manufactured by Lonza) as an agent was added to 0.03 part, and ion-exchanged water was further added so that the non-volatile content was 22%. . Next, ultrasonic irradiation was performed for 10 minutes under ice cooling using an ultrasonic irradiation machine (trade name “UP400S”, manufactured by Hielscher). The amplitude of the ultrasonic irradiator was 70%.
Subsequently, Denacol EX321 (epoxy crosslinking agent, manufactured by Nagase ChemteX, non-volatile content: 100%, epoxy equivalent: 140 g / eq) as a crosslinking agent was used in a colorant particle having a carboxylic acid / crosslinking agent molar ratio of 0.1. 0.82 part was added so that it might become 3 eq, and also it stirred for about 1 hour, and it adjusted with ion-exchange water again so that a non volatile matter might be 22%, and obtained the colorant dispersion C-1.

[Examples 2 to 18, Comparative Examples 1 to 4]
(Colorant dispersion C-2 to C-22)
Colorant dispersions C-2 to C-20 and C-22 were obtained in the same manner as in Example 1 except that the colorant particles to be used, the crosslinking agent type, and the amount of the crosslinking agent were changed according to Table 3. C-21 was obtained in the same manner as in Example 1 except that no basic compound was added.

<Evaluation of colorant dispersion>
The following evaluation was performed about the obtained colorant dispersion. The results are shown in Table 3.

(Volume median diameter D50)
The obtained colorant dispersion was diluted with water 500 times, and about 5 ml of the diluted solution was measured by a dynamic light scattering measurement method (measurement apparatus manufactured by Nikkiso Co., Ltd.). At this time, the peak of the obtained volume particle size distribution data (histogram) was defined as (D50).

(Initial viscosity and storage stability over time)
The initial viscosity of the colorant dispersion was measured using an E-type viscometer (“ELD viscometer” manufactured by Toki Sangyo Co., Ltd.) at 25 ° C. under the condition of a rotation speed of 20 rpm. Furthermore, after the colorant dispersion was stored in a thermostat at 70 ° C. for 1 week and accelerated over time, the viscosity was measured in the same manner, the rate of change in viscosity before and after aging was calculated, and evaluated according to the following criteria.
○: Viscosity change rate is less than ± 10% (good)
Δ: Viscosity change rate is ± 10% or more and less than ± 20% (no problem in practical use)
×: Viscosity change rate is ± 20% or more (defect)

The abbreviations in Table 3 are shown below.
Denacol EX321: manufactured by Nagase ChemteX, epoxy crosslinking agent, non-volatile content: 100%, epoxy equivalent: 140 g / eq
Chemitite D22E: manufactured by Nippon Shokubai Co., Ltd., aziridine crosslinking agent, nonvolatile content 30%, aziridine equivalent 168 g / eq
Carbodilite V02: Nisshinbo, carbodiimide cross-linking agent, non-volatile content 40%, carbodiimide equivalent 590 g / eq

<Manufacture of ink for ink jet recording>
[Examples 19 to 36, Comparative Examples 5 to 8]
(Inkjet recording inks J-1 to J-22)
33.3 parts of the colorant dispersion obtained in Examples and Comparative Examples, 16.65 parts of propylene glycol, 16.65 parts of 1,2-hexanediol, 33.3 parts of ion-exchanged water, leveling agent As a result, 0.1 part of Surfinol DF110D (manufactured by Air Products Japan) was mixed to prepare inkjet recording inks J-1 to J-22.

<Evaluation of ink for inkjet recording>
The following evaluation was performed about the obtained colorant dispersion. The results are shown in Table 4.

(Change rate of volume median diameter)
The obtained ink for inkjet recording was diluted 100 times with water, and about 5 ml of the diluted solution was measured by a dynamic light scattering measurement method (measurement apparatus manufactured by Nikkiso Co., Ltd.). At this time, the peak of the obtained volume particle size distribution data (histogram) was defined as (D50). The particle size change rate was calculated by comparison with the D50 value of the colorant dispersion, and evaluated according to the following criteria. The smaller the particle size change in the ink making process, the higher the evaluation.
A: Particle size change rate is less than ± 5% (very good)
○: Particle size change rate is ± 5% or more and less than ± 15% (good)
Δ: Change rate of particle size is ± 10% or more and less than ± 25% (no problem in practical use)
×: Particle size change rate is ± 25% or more (defect)

(Initial viscosity and storage stability over time)
Measurement and evaluation were performed in the same manner as the colorant dispersion.

(Print evaluation)
The obtained ink for ink-jet recording was packed in a cartridge of an ink-jet printer ("PM-750C" manufactured by Epson Corporation) and printed on coated paper (Oji Paper's OK Top Coat +, US basis weight 104.7 g / m < ² >). The printed sample was observed with a magnifying glass to evaluate dot connection and color unevenness, and evaluated according to the following criteria.
○: No dot connection or color unevenness (very good)
Δ: Slightly connected dots and uneven color (no problem in practical use)
X: Connection of dots and color unevenness are on the entire surface (defect)

From the results of Tables 3 and 4, it was shown that when the unneutralized resin adsorption amount is 30% by mass or more, a colorant dispersion and ink jet recording ink excellent in storage stability with time and printability are obtained. This is because the adsorption and coating of the unneutralized resin on the surface of the colorant is sufficient, the reaction between the unneutralized resin adsorbed on the colorant and the crosslinking agent proceeds effectively, and the colorant is strongly resin-coated. This is considered to be because stability was maintained even when a highly permeable solvent or a solvent having a high boiling point was added. In particular, when the unneutralized resin adsorption amount was 60% by mass or more, the rate of change in the volume median diameter of the ink for inkjet recording was very good.
Examples 10 to 13 and 28 to 31 indicate that the amount of resin adsorbed to the colorant is particularly improved when the weight average molecular weight of the unneutralized resin is 5,000 to 15,000.
From Examples 1 to 3 and 19 to 21, when m in the general formula (1) contained in the non-neutralized resin is 9 or more and 40 or less, the affinity of the non-neutralized resin to the water-soluble organic solvent is moderate. It is considered that the resin adsorption amount is improved. In addition, in the colorant dispersion and the ink for ink jet recording, these are considered to be highly effective as a steric hindrance group and improved in stability because the alkyleneoxy group has a large spread in the ink.
Further, it was shown that when the acid value of the non-neutralized resin is 120 to 300 mgKOH / g, the storage stability with time of the ink for inkjet recording is more excellent. This is presumably because the adsorbing power to the colorant was improved due to the appropriate acid value.

Claims (9)

A colorant dispersion comprising colorant particles, a basic compound, a crosslinking agent and water,
The colorant particles adsorb an unneutralized resin having an alkyleneoxy group having 1 to 6 carbon atoms and a carboxyl group on the surface of the colorant, and adsorb the unneutralized resin to the colorant in the colorant particles. A colorant dispersion which is colorant particles whose amount (unneutralized resin adsorption rate) is 30% by mass or more. The colorant dispersion according to claim 1, wherein the weight-average molecular weight of the non-neutralized resin having an alkyleneoxy group having 1 to 6 carbon atoms and a carboxyl group is 5,000 to 15,000. The colorant dispersion according to claim 1 or 2, wherein a volume median diameter by a dynamic light scattering method is 20 to 100 nm. The colorant dispersion according to any one of claims 1 to 3, wherein the acid value of the non-neutralized resin having an alkyleneoxy group having 1 to 6 carbon atoms and a carboxyl group is 120 to 300 mgKOH / g. The colorant dispersion according to any one of claims 1 to 4, wherein the crosslinking agent comprises at least one group selected from the group consisting of an aziridine group, a carbodiimide group, and an epoxy group. The colorant dispersion according to any one of claims 1 to 5, wherein the unneutralized resin adsorption rate is 60% by mass or more. The colorant for stationery, the colorant for paint, the colorant for printing ink, the colorant for electrophotography, the colorant for ink for inkjet recording, or the colorant for textile printing agent, according to any one of claims 1 to 6. Colorant dispersion. A step of kneading and refining a mixture containing a colorant, an unneutralized resin having an alkyleneoxy group having 1 to 6 carbon atoms, and a carboxyl group, a water-soluble inorganic salt and a water-soluble organic solvent; A step of removing the salt and the water-soluble organic solvent, a step of adding a basic compound and water to neutralize the carboxyl group of the unneutralized resin, a cross-linking agent to add the cross-linking agent and the non-neutralized resin A method for producing a colorant dispersion, wherein the crosslinking step is sequentially performed. An ink for inkjet recording, comprising the colorant dispersion according to claim 1.