JP6255953B2 - Method for producing kneaded product for aqueous pigment dispersion and method for producing aqueous pigment dispersion and ink composition using the same - Google Patents

Description

  The present invention relates to a method for producing a kneaded product for an aqueous pigment dispersion particularly suitable for inkjet recording, and an aqueous pigment dispersion and an ink composition using the same.

  Inkjet recording systems have a growing tendency from home use to office use, photography use, and outdoor use, and the weather resistance (light) resistance and storage stability of printed matter are emphasized. The dyes that have been at the center of ink-jet recording colorants have many problems in terms of light resistance, and accordingly, development of water-based inks for ink-jet recording using pigments having excellent light resistance has been promoted.

Since the pigment is insoluble in water, a technique for stably dispersing it in an aqueous medium is required. Generally, the dispersion of the pigment is reversible, and even if it can be dispersed, it is said that it is difficult to keep the dispersion state stable unless measures are taken to suppress reaggregation of the pigment. For this reason, most of them are called a group called an anchor having a strong affinity for the pigment surface, and a chain having an affinity for a dispersion medium (the dispersion medium here refers to a liquid medium used at the time of dispersion) or a binder resin. A resin having both groups is used as a dispersant, and a resin layer is formed on the surface of the pigment particles to stabilize the dispersion. (For example, see Non-Patent Document 1)
As a method capable of stabilizing the dispersion by forming a resin layer on the pigment particle surface, a dispersion method via a pretreatment step in which a pigment and a polymer dispersant are previously kneaded has been proposed (for example, patents). Reference 1). Dispersion can be further stabilized by forming a resin layer on the pigment particle surface more efficiently through a pretreatment step in which a pigment and a polymer dispersant are previously kneaded, and the production efficiency is improved. Can be made into fine particles.

On the other hand, the dispersant used also affects the dispersion stability. Conventionally, as a dispersant, a self-water-dispersible resin obtained by neutralizing a part of acid groups with a base (b), for example, a styrene- (meth) acrylic acid system in which a part of a (meth) acrylic acid group is neutralized A method including, for example, a method of diluting an aqueous medium in which a pigment is encapsulated with a copolymer (see, for example, Patent Document 2), a hydrophobic segment, and a hydrophilic segment including a hydrophobic unit and a hydrophilic unit. A method of using a block polymer compound characterized by having as a pigment dispersant is known (for example, see Patent Document 3).
However, even when the aqueous pigment dispersion obtained by using these dispersants is the method described in Patent Document 1, coarse particles may be generated.

Japanese Patent Laid-Open No. 2003-226832 JP 2007-238949 A JP 2008-195769 A

63-64 pages of organic pigment handbook (issued in color by the first edition issued in May 2006)

  An object of the present invention is to provide a kneaded product for an aqueous pigment dispersion in which coarse particles are reduced, an aqueous pigment dispersion, and an ink composition excellent in ejection stability using the same.

  The present inventors knead a mixture containing a pigment, a basic compound, and an anionic group-containing polymer used as a pigment dispersant in a closed kneading apparatus, and has a solid content of 50 to 80% by mass. In the method for producing a kneaded product for an aqueous pigment dispersion for producing a solid kneaded pigment kneaded product, the above-mentioned problems have been solved by using a resin having a specific block structure as a pigment dispersant.

  That is, the present invention is a mixture of a pigment, a basic compound, and an anionic group-containing polymer, kneaded with a closed kneading apparatus, and a solid-content pigment kneaded mixture at a normal temperature of 50 to 80% by mass. In the method for producing a kneaded product for an aqueous pigment dispersion, the method for producing a kneaded product for an aqueous pigment dispersion using the polymer represented by the general formula (1) as the anionic group-containing polymer is provided.

（１）

(1)

(In Formula (1), A ¹ represents an organolithium initiator residue, A ² represents a repeating unit of a styrene monomer and / or a vinylpyridine monomer residue, and A ³ represents (meth) acrylic acid and / or Or (repeat unit of (meth) acrylate monomer residue)

  The present invention also includes a step of obtaining a kneaded product for an aqueous pigment dispersion by the method for producing a kneaded product for an aqueous pigment dispersion described above, and the kneaded product for an aqueous pigment dispersion is dispersed in a water-soluble solvent to obtain an aqueous solution. A method for producing an aqueous pigment dispersion having a step of obtaining a pigment dispersion.

  The present invention also provides an ink composition production method for producing an ink composition by diluting an aqueous pigment dispersion obtained by the above-described method for producing an aqueous pigment dispersion with a water-soluble solvent.

  According to the present invention, an aqueous pigment dispersion kneaded product or an aqueous pigment dispersion with reduced coarse particles can be obtained, and an ink composition excellent in ejection stability can be obtained using the kneaded product.

(Pigment)
The pigment used in the present invention is not particularly limited, and organic pigments or inorganic pigments usually used in water-based inkjet inks can be used. Either untreated pigment or treated pigment can be applied. In the case of printing using plastic as a recording material, in addition to yellow ink, cyan ink, magenta ink, black ink, etc., white ink is also used for the purpose of improving visibility.

  These pigments used are not particularly limited, and those usually used as pigments for water-based inkjet recording inks can be used. Specifically, it can be dispersed in water or a water-soluble organic solvent, and a known inorganic pigment or organic pigment can be used. Examples of the inorganic pigment include carbon black produced by a known method such as iron oxide, a contact method, a furnace method, and a thermal method. Organic pigments include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments), polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazines). Pigments, thioindigo pigments, isoindolinone pigments, quinofullerone pigments, etc.), dye chelates (for example, basic dye chelates, acidic dye chelates, etc.), nitro pigments, nitroso pigments, aniline black, and the like.

  For example, as a pigment used for black ink, as carbon black, No. manufactured by Mitsubishi Chemical Corporation. 2300, no. 2200B, no. 900, no. 960, no. 980, no. 33, no. 40, No, 45, No. 45L, no. 52, HCF88, MA7, MA8, MA100, etc. are Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255, Raven 700, etc. manufactured by Columbia, Regal 400R, Regal 330R, Regal 660R, Mull 660R, Mull 660R Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc. are Color Black FW1, FW2, FW2V, FW18, FW200, S170, U , V, 1400U, Special Bla k 6, the 5, 4, 4A, NIPEX150, NIPEX160, NIPEX170, NIPEX180 and the like.

  Specific examples of pigments used for yellow ink include C.I. I. Pigment Yellow 1, 2, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 120, 128, 129, 138, 150, 151, 154, 155, 174, 180, 185 and the like.

Specific examples of pigments used in magenta ink include C.I. I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 122, 123, 146, 168, 176, 184, 185, 202, 209, etc. It is done.

  Specific examples of pigments used for cyan ink include C.I. I. Pigment blue 1, 2, 3, 15, 15: 3, 15: 4, 16, 22, 60, 63, 66, and the like.

  Specific examples of pigments used in white inks include silicas such as alkaline earth metal sulfates, carbonates, finely divided silicic acids, synthetic silicates, calcium silicates, alumina, alumina hydrates, Examples thereof include titanium oxide, zinc oxide, talc, and clay. The inorganic white pigment may be surface-treated by various surface treatment methods.

The pigment is blended in the mixture by 35% by mass or more, preferably 40% by mass or more. In general, in order to obtain an ink composition having a constant pigment concentration by diluting the aqueous pigment dispersion, it is necessary to increase the concentration in the aqueous pigment dispersion as much as possible because it is possible to produce more ink compositions. It will be advantageous. However, increasing the pigment concentration deteriorates the storage stability of the aqueous pigment dispersion. Therefore, from the viewpoint of securing the stability of the pigment dispersion stability and the kneaded product for the aqueous pigment dispersion, 60 mass % Or less, preferably 50 mass% or less.
Further, regarding the mass ratio of the pigment (Pigment) and the polymer (Resin) represented by the general formula (1) used as a dispersant described later, the resin is present in an amount necessary to stably coat the pigment surface. It is sufficient that the content of the resin exceeds that. When an excessive amount of resin is present, free resin that does not adsorb to the pigment increases when an aqueous pigment dispersion or an ink composition is prepared. In particular, the thermal jet printer has a high risk of causing this ejection failure problem.
Therefore, in the production of the aqueous pigment dispersion kneaded product of the present invention, it is preferable that the mass ratio of resin / pigment is 1/10 to 2/1, preferably 1/10 to 1/1. If the blending ratio of the pigment is too small relative to the resin, the above-mentioned problems are likely to occur. If the blending ratio of the pigment is too large, the pigment is not sufficiently covered with the resin, and the dispersion stability and long-term storage stability decrease. There is a fear.

(Polymer represented by general formula (1))
The anionic group-containing polymer used in the present invention is specifically a polymer represented by the general formula (1).

（１）

(1)

In the general formula (1), A ¹ represents an organic lithium initiator residues. Specific examples of the organic lithium initiator include methyl lithium, ethyl lithium, propyl lithium, butyl lithium (n-butyl lithium, sec-butyl lithium, iso-butyl lithium, tert-butyl lithium, etc.), pentyl lithium, hexyl lithium, Alkyllithium such as methoxymethyllithium and ethoxymethyllithium; benzyllithium such as benzyllithium, α-methylstyryllithium, 1,1-diphenyl-3-methylpentyllithium, 1,1-diphenylhexyllithium; vinyllithium, allyl Alkenyl lithium such as lithium, propenyl lithium, butenyl lithium; alkynyl lithium such as ethynyl lithium, butynyl lithium, pentynyl lithium, hexynyl lithium;

Aralkyl lithium such as phenylethyl lithium; aryl lithium such as phenyl lithium and naphthyl lithium; heterocyclic lithium such as 2-thienyl lithium, 4-pyridyl lithium and 2-quinolyl lithium; tri (n-butyl) magnesium lithium and trimethyl magnesium Examples thereof include alkyl lithium magnesium complexes such as lithium.

In the general formula (1), A ² is a hydrophobic block intended for adsorption to the pigment, and represents a repeating unit of a styrene monomer and / or vinyl pyridine monomer residue, that is, a styrene monomer and / or vinyl. It is a polymer obtained by homopolymerization or copolymerization of a pyridine monomer.
Specific examples of the styrenic monomer include styrene, styrene derivatives (p-dimethylsilylstoxystyrene, p-tert-butyldimethylsiloxystyrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, α- Methyl styrene), vinyl naphthalene, vinyl anthracene, 1,1-diphenylethylene and the like.
Examples of the vinyl pyridine monomer include 2-vinyl pyridine and 4-vinyl pyridine. These monomers can be used alone or in admixture of two or more.

In the general formula (1), A ³ is a hydrophilic block for imparting dispersion stability, and represents a repeating unit of (meth) acrylic acid and / or (meth) acrylic acid ester monomer residue, that is, (meta ) A polymer having a hydrophilic group such as an anionic group obtained by homopolymerization or copolymerization of acrylic acid and / or (meth) acrylic acid ester monomer.
In the present invention, (meth) acrylic acid represents the generic name of acrylic acid and methacrylic acid, and (meth) acrylic acid ester monomer represents the generic name of acrylic acid ester monomer and methacrylic acid ester monomer.

  Specific examples of (meth) acrylic acid and (meth) acrylic acid ester monomers include (meth) acrylic acid, methyl (meth) acrylate, ethyl (meth) acrylate, iso-propyl (meth) acrylate, (meth ) Allyl acrylate, n-butyl (meth) acrylate, iso-butyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-amyl (meth) acrylate, Iso-amyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-lauryl (meth) acrylate, (meth) acrylic acid n-tridecyl, n-stearyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, (meth ) Acrylic acid cyclohexyl, (meth) acrylic acid 4-tert-butylcyclohexyl, (meth) acrylic acid isobornyl, (meth) acrylic acid tricyclodecanyl, (meth) acrylic acid dicyclopentadienyl, (meth) acrylic acid Adamantyl, glycidyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, (meth) Diethylaminoethyl acrylate, trifluoroethyl methacrylate, tetrafluoropropyl methacrylate, pentafluoropropyl methacrylate, octafluoropentyl methacrylate, pentadecafluorooctyl methacrylate, heptadecafluorodecyl methacrylate, , N- dimethyl (meth) acrylamide, acryloyl morpholine, (meth) acrylonitrile,

Polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, polyethylene glycol-polypropylene glycol (meth) acrylate, polyethylene glycol-polybutylene glycol (meth) acrylate, polypropylene glycol-polybutylene glycol (meth) acrylate, methoxypolyethylene glycol ( (Meth) acrylate, ethoxypolyethyleneglycol (meth) acrylate, butoxypolyethyleneglycol (meth) acrylate, octoxypolyethyleneglycol (meth) acrylate, lauroxypolyethyleneglycol (meth) acrylate, stearoxypolyethyleneglycol (meth) acrylate, phenoxypolyethyleneglycol (Meta) acryle DOO, methoxy polypropylene glycol (meth) acrylate, octoxypolyethylene glycol - polyalkylene oxide group-containing polypropylene glycol (meth) acrylate (meth) acrylic monomer, and the like. These monomers can be used alone or in admixture of two or more.

The A ³ is an ester of a polymer having no anionic group obtained by homopolymerizing or copolymerizing the (meth) acrylic acid, or by homopolymerizing or copolymerizing the (meth) acrylic acid ester monomer. It can also be obtained by hydrolyzing the bond to express a carboxyl group.

The polymer represented by the general formula (1) is preferably produced by living polymerization such as living radical polymerization and living anion polymerization. In particular, since it is advantageous to clarify the block in terms of the stability of the dispersion, it is preferably produced by living anionic polymerization.
Examples of the living anionic polymerization method include a polymerization method using a microreactor. Since the microreactor has a good mixing property between the polymerization initiator and the monomer, the reaction starts at the same time, the temperature is uniform and the polymerization rate can be made uniform, and therefore the molecular weight distribution of the produced polymer can be narrowed. At the same time, since the growth terminal is stable, it becomes easy to produce a block copolymer. Moreover, since the controllability of the reaction temperature is good, it is easy to suppress side reactions.

(Living anion polymerization using microreactor)
An example of a specific embodiment will be described with reference to FIG. 1, which is a schematic diagram of a microreactor. A T-shaped micromixer M1 having a flow path capable of mixing a plurality of liquids from the tube reactors P1 and P2 (7 and 8 in FIG. 1), respectively, with the first monomer and the polymerization initiator for initiating the polymerization is shown. 1), the first monomer is subjected to living anion polymerization in the T-shaped micromixer M1 to form a first polymer (step 1).

  Next, the obtained first polymer is moved to the T-shaped micromixer M2 (2 in FIG. 1), and the growth terminal of the obtained polymer is moved into the tube reactor P3 (FIG. 1) in the mixer M2. The reaction is controlled by trapping with 1,1-diphenylethylene, which is the reaction regulator introduced from the middle 9) (Step 2).

Next, the first polymer subjected to reaction control in the T-shaped micromixer M2 is moved to the T-shaped micromixer M3 (3 in FIG. 1), and the tube reactor P4 is moved in the mixer M3. The introduced second monomer and the first polymer subjected to the reaction control are continuously subjected to living anion polymerization (step 3).
Thereafter, the reaction is quenched with methanol to produce a block copolymer having no anionic group.

In the living anion polymerization method using a microreactor, when the monomer used has a functional group such as a hydroxyl group or an acid group, it is difficult to polymerize as it is in the living anion polymerization. Thereafter, it is preferable to remove the protecting group.
Thus, in the living anionic polymerization method using a microreactor, wherein A ³ after synthesizing a polymer without the (meth) anionic groups obtained by homopolymerization or copolymerization of acrylic acid ester monomer, an ester bond It is obtained by a method of hydrolyzing and expressing a carboxyl group.

The polymer represented by the general formula (1) of the present invention uses a styrene monomer and / or a vinylpyridine monomer as the first monomer, and reacts with an organolithium initiator as the initiator. obtaining a polymer comprising a hydrophobic block of a ^2. Next, 1,1-diphenylethylene is used as the reaction modifier to adjust the reactivity at the growth end, and then a (meth) acrylate monomer is reacted as the second monomer to obtain a polymer. Thereafter, by some or all of the ester bond the polymer has is hydrolyzed to express a carboxyl group, a hydrophilic block of the A ³ is obtained.

A method for expressing a carboxyl group by hydrolyzing part or all of the ester bond of the polymer will be described in detail.
The hydrolysis reaction of the ester bond proceeds under acidic conditions or basic conditions, but the conditions are slightly different depending on the group having an ester bond. For example, when the group having an ester bond is a primary alkoxycarbonyl group such as a methoxycarbonyl group or a secondary alkoxycarbonyl group such as an isopropoxycarbonyl group, it is converted to a carboxyl group by hydrolysis under basic conditions. it can. In this case, examples of the basic compound to be subjected to basic conditions include metal hydroxides such as sodium hydroxide and potassium hydroxide. This reaction proceeds quantitatively.

  When the group having an ester bond is a tertiary alkoxycarbonyl group such as a t-butoxycarbonyl group, it can be converted to a carboxyl group by hydrolysis under acidic conditions. In this case, examples of acidic compounds to be used under acidic conditions include mineral acids such as hydrochloric acid, sulfuric acid, and phosphoric acid; Breasted acids such as trifluoroacetic acid; Lewis acids such as trimethylsilyl triflate. This reaction proceeds quantitatively. The reaction conditions for hydrolysis under acidic conditions of the t-butoxycarbonyl group are disclosed in, for example, “The Chemical Society of Japan, 5th edition, Experimental Chemistry Course 16 Synthesis of Organic Compounds IV”.

  Furthermore, as a method for converting a t-butoxycarbonyl group into a carboxyl group, a method using a cation exchange resin in place of the above-mentioned acid may be mentioned. As said cation exchange resin, resin which has acid groups, such as a carboxyl group (-COOH) and a sulfo group (-SO3H), is mentioned in the side chain of a polymer chain, for example. Among these, a strongly acidic cation exchange resin having a sulfo group in the side chain of the polymer chain is preferable because the reaction can proceed rapidly. Examples of commercially available cation exchange resins that can be used in the present invention include strongly acidic cation exchange resin “Amberlite” manufactured by Organo Corporation. Since the amount of the cation exchange resin used can be effectively hydrolyzed, the range of 0.01 to 10 parts by mass is preferable with respect to 100 parts by mass of the polymer represented by the general formula (1). A range of ˜5 parts by mass is more preferred.

  Further, when the group having an ester bond is a phenylalkoxycarbonyl group such as a benzyloxycarbonyl group, it can be converted to a carboxyl group by performing a hydrogenation reduction reaction. In this case, as the reaction conditions, the phenylalkoxycarbonyl group can be quantitatively converted into a carboxyl group by performing a reaction using hydrogen gas as a reducing agent at room temperature in the presence of a palladium catalyst such as palladium acetate.

As described above, since the reaction conditions for conversion to a carboxyl group differ depending on the type of group having an ester bond, for example, when t-butyl (meth) acrylate is used as a raw material for A ³ , for example, n-butyl ( A polymer obtained by copolymerization using a (meth) acrylate has a t-butoxycarbonyl group and an n-butoxycarbonyl group. Here, since the n-butoxycarbonyl group does not hydrolyze under acidic conditions in which the t-butoxycarbonyl group is hydrolyzed, only the t-butoxycarbonyl group can be selectively hydrolyzed and converted to a carboxyl group. Become. Therefore, it is possible to the acid value of the adjustment of the raw material monomer of the A ³ (meth) hydrophilic block by appropriately selecting the acrylic acid ester monomer (A ^3).

In the polymer, it is advantageous in terms of stability of the obtained aqueous pigment dispersion that the hydrophobic block (A ² ) and the hydrophilic block (A ³ ) are clearly separated. The molar ratio A ² : A ³ between the hydrophobic block (A ² ) and the hydrophilic block (A ³ ) is preferably in the range of 100: 5 to 100: 500. If the ratio of A ³ is less than 5 per 100 of A ^2, it tends to be inferior in ejection stability at the time of dispersion stability and inkjet discharge of the pigment. On the other hand if the ratio of A ³ coming exceed 500 per 100 of A ^2, too high hydrophilicity of the polymer, the recording medium is apt to penetrate into the the case of paper or the like, reduction coloring property To do. In particular, the ratio is preferably A ² : A ³ = 100: 5 to 100: 450.

The weight average molecular weight of the polymer is preferably 1500 to 10,000, more preferably 1500 to 8000, and most preferably in the range of 1500 to 4500. When the weight average molecular weight is less than 1500, steric hindrance due to molecular chains may be reduced, and the stability of the aqueous pigment dispersion that may be obtained may be lowered. When the weight average molecular weight exceeds 10,000, the permeability to the pigment aggregate tends to be weak and the disintegration property of the pigment aggregate tends to be low, and it becomes difficult to disperse the pigment easily, resulting in a large dispersed particle size. There is a risk that the color developability is lowered.
The weight average molecular weight is a value in terms of polystyrene measured by GPC (gel permeation chromatography).

The acid value of the polymer is preferably 40 to 400 mgKOH / g, more preferably 40 to 300 mgKOH / g. When the acid value is less than 40 mgKOH / g, the dispersion stability of the pigment and the ejection stability during inkjet ejection are not sufficient. On the other hand, when the acid value exceeds 400 mgKOH / g, the hydrophilicity of the polymer increases, and the color developability decreases because it easily penetrates into the recording medium.
In addition, the acid value of the polymer in the invention was an acid value obtained by the following acid value measurement method of the polymer.

[Measurement method of acid value]
It measured based on JIS test method K0070-1992. This was determined by dissolving 0.1 g of a sample in a mixed solvent of methanol and toluene, and titrating with 0.1 M potassium hydroxide alcohol solution using phenolphthalein as an indicator.

(Basic compound)
By mixing the polymer and the basic compound, the affinity between the aqueous pigment dispersion kneaded product and water is improved, and the aqueous pigment dispersion kneaded product can be quickly submerged in water during the production of the aqueous pigment dispersion. Dispersion improves production efficiency. Further, the dispersion state of the resin-coated pigment particles in the aqueous pigment dispersion becomes more stable, and the dispersion stability and long-term storage stability are also improved.
In addition, when a basic compound is blended during kneading, the resin is likely to be in a dissolved state or a swollen state due to the interaction between the basic compound and the polymer, and the pigment can be kneaded in a state where the resin is sufficiently covered with the resin. Therefore, the pigment is finely pulverized during the kneading, and the coarse particles are likely to be reduced. The step of removing the coarse particles in the subsequent step can be omitted, and the yield can be improved.

As the basic compound, any of an inorganic basic compound and an organic basic compound can be used. In terms of easy adjustment of alkali strength, inorganic basic compounds are more preferable. Examples of the organic basic compound include amines. For example, common amines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine and triethylamine can be exemplified. In the case of amine, since it is generally liquid, it can be used as it is.
Examples of inorganic basic compounds include alkali metal hydroxides such as potassium and sodium, ammonium hydroxide; alkaline metal carbonates such as potassium and sodium, alkaline earth metal carbonates such as calcium and barium; It can be illustrated.
Among them, a strong alkali is preferable because it is effective for enhancing the dispersibility of the resin by neutralization of the polymer. Specifically, alkali metal hydroxides such as potassium hydroxide and sodium hydroxide are preferable. preferable.
The inorganic basic compound is usually used in the form of an aqueous solution having a concentration of about 20 to 50% by mass from the viewpoint of improving the mixing property.

The blending amount of the basic compound is set so that the neutralization rate of the polymer is 20% or more, preferably 40% or more, so that the dispersion rate in the water-soluble solvent is improved, the dispersion stability, and the long-term storage. It is preferable from the viewpoint of stability. Although the upper limit is not particularly limited, it is substantially 200% or less, preferably 120% or less in order to have dispersion stability during long-term storage and not to gel.
Furthermore, before kneading, the basic compound is preferably mixed together with other blending components to be blended into the mixture to prepare a mixture.
For example, the mixture is prepared by mixing the polymer, water and a basic compound in advance to prepare an aqueous resin solution, adding this to other compounding ingredients such as pigments, etc., and mixing in multiple stages. However, it is preferable to prepare a mixture for kneading by batch mixing the basic compound and other compounding components from the viewpoint of efficient adsorption of the resin to the surface of the pigment.
Here, the neutralization rate is a value calculated by the following formula.

(Water-soluble organic solvent)
In producing the kneaded product for an aqueous pigment dispersion of the present invention, it is preferable to knead in the presence of a certain amount of solvent. If the solvent is not present, it cannot be sufficiently kneaded or the surface of the pigment does not get wet, so that the resin coating may be insufficient. Therefore, when a water-soluble organic solvent is blended in the kneaded product for an aqueous pigment dispersion, the polymer is dissolved, partially dissolved, or swollen with the water-soluble organic solvent, thereby forming a uniform resin coating on the surface of the pigment particles. Can be formed. As a result, the dispersion stability can be further improved in the aqueous pigment dispersion and the ink composition.
In addition, when an aqueous solution of a basic compound is used, or when the basic compound is in a liquid state like an amine, these serve as the above-mentioned solvent, so there is no need to add a water-soluble organic solvent. is there.

As the water-soluble organic solvent, known ones can be used without particular limitation.
For example, glycols such as ethylene glycol, diethylene glycol, triethylene glycol tetraethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol;
Diols such as butanediol, pentanediol, hexanediol, and diols of the same family;
Glycol esters such as propylene glycol laurate;
Glycol ethers such as cellosolve including diethylene glycol monoethyl, diethylene glycol monobutyl, diethylene glycol 11111 monohexyl ether, propylene glycol ether, dipropylene glycol ether, and triethylene glycol ether;
Alcohols such as methanol, ethanol, isopropyl alcohol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, butyl alcohol, pentyl alcohol, and alcohols homologous thereto;
Alternatively, sulfolane; lactones such as γ-butyrolactone; lactams such as N- (2-hydroxyethyl) pyrrolidone; various other solvents known as water-soluble organic solvents such as glycerin and derivatives thereof can be used. .
These water-soluble organic solvents can be used alone or in combination.
The selection of the water-soluble organic solvent is determined depending on the resin to be used, but a solvent having a certain degree of solubility is preferable, and the addition amount is adjusted by the solubility of the resin.

Among them, polyhydric alcohols having a high boiling point, low volatility, and high surface tension at room temperature are preferred, particularly diethylene glycol, since they also serve as wetting agents and drying inhibitors in aqueous pigment dispersions and ink compositions. And glycols such as triethylene glycol are preferred. In general, glycols are often contained in ink compositions, and there is no problem even if they remain in the final product.
In particular, since the kneading is performed in the presence of a basic compound in the production method of the present invention, a water-soluble organic solvent having a particularly high resin dissolving power is not necessary.

In addition, although a water-soluble organic solvent changes also with resin to be used, it is normally 10-50 mass% in a mixture of preparation, Preferably 20-40 mass% is mix | blended. The addition amount is about 1/2 to 5 times the resin amount, and preferably about 1 to 4 times the resin amount. If the amount of the water-soluble organic solvent is less than ½ of the resin amount, the resin cannot be dissolved, partially dissolved, or swollen, and the dispersion stability of the pigment may be lowered. On the other hand, if it exceeds 5 times, the viscosity of the mixture for kneading is lowered and sufficient kneading cannot be performed, so that the dispersibility of the pigment is lowered, and there is a risk of causing image quality deterioration such as ejection failure in the ink composition. In addition, as mentioned above, when what is derived from a basic compound etc. and plays the role of a solvent is mix | blended, it is preferable to determine the compounding quantity of a water-soluble organic solvent in consideration of this.
In addition, the water-soluble organic solvent is preferably added to the pigment in a mass ratio of 1/5 or more, preferably 1/3 to 1 times. As a result, the kneading step proceeds while the resin is always in a semi-dissolved or swollen state, and the resin coating is favorably performed on the pigment surface. If it is less than 1/5, the surface of the pigment cannot be sufficiently wet at the initial stage of kneading, or the resin cannot be dissolved, partially dissolved, or swollen, and the effect may not be sufficiently obtained. .

(Kneading method)
In the production method of the present invention, the polymer represented by the general formula (1) is used as a pigment dispersant, kneaded with a pigment and a basic compound in a closed kneading apparatus, and the solid content is 50 to 80 mass. %, It is a so-called kneading method for producing a pigment kneaded material which is kneaded at room temperature.

The kneading method is a method described in Patent Document 1 and is a method in which mixing of impurities is very small because kneading is performed with a closed kneader.
In this method, the pigment is not directly dispersed in the water-soluble solvent, but first, the pigment is kneaded with the resin or the like and then dispersed in the water-soluble solvent. Therefore, since the pigment is finely pulverized during the kneading, coarse particles can be reduced.
At this time, since the basic compound is added as described above, the kneading viscosity of the kneaded product increases due to the interaction between the basic compound and the polymer, and the kneading proceeds with a high shearing force, resulting in a significant decrease in coarse particles. To do. Therefore, the step of removing the coarse particles can be omitted, and the production efficiency can be improved and the yield can be improved.

  A constant amount of water-soluble organic solvent is always present in the mixture from the start to the end of kneading, so that the water-soluble organic solvent that wets the surface of the pigment at the initial stage of kneading is preferably dissolved, swollen, or It is assumed that the pigment is replaced with the partially dissolved anionic group-containing polymer, and the coating of the pigment with the anionic group-containing polymer proceeds smoothly, and a pigment sufficiently coated with the anionic group-containing polymer can be obtained. . Further, even after the completion of the kneading, almost the same amount of the solvent remains as at the start of the kneading, so that the dissolution and dispersion of the mixture after the kneading can proceed in a very short time.

The closed kneader used in the kneading method is preferably a kneader equipped with a stirring tank and a uniaxial or multiaxial stirring blade. The number of stirring blades is not particularly limited, but two or more stirring blades are preferable in order to obtain a high kneading action.
When a kneader having such a configuration is used, a kneaded product for an aqueous pigment dispersion can be produced and then diluted and dispersed directly with a water-soluble solvent in the same stirring tank to produce an aqueous pigment dispersion. it can. The fact that the mass does not change substantially means that the weight of the kneaded material during or after kneading is preferably maintained in the range of 90% by mass or more with respect to the amount of the mixture before kneading. And

  Examples of the closed-type kneader including a sealable stirring tank and a single-shaft or multi-shaft stirring blade used in the kneading method include a Henschel mixer, a pressure kneader, a Banbury mixer, and a planetary mixer. . In the present invention, the kneader is preferably a planetary mixer. The planetary mixer has a structure in which the kneaded material in the stirring tank is stirred and kneaded using biaxial stirring blades that rotate and revolve with each other, and the dead space where the stirring blades do not reach in the stirring tank Less is. Moreover, although the shape of a blade | wing is thick and can apply high load, on the other hand, it can also be used like the normal stirrer which rotates a stirring blade in a stirring tank. For this reason, there is a wide range of materials to be kneaded from the high load region to the low load region, and one or both of water and a water-soluble organic solvent are added to the kneaded material after completion of the kneading for dilution. All of the stirring and dispersion can be performed in the same mixer without removing the kneaded product from the planetary mixer.

In the kneading method, the viscosity varies in a wide range depending on the kneading state of the kneaded product because the kneading is performed in a state where the solid content ratio composed of the pigment and the anionic group-containing polymer is high. It is possible to deal with a wide range up to the viscosity.
Specifically, the higher the solid content ratio in the mixture, the higher the viscosity of the kneaded product during kneading, and the greater the shear (shearing force) applied to the kneaded product by the kneader during kneading. The pulverization of the pigment in the product and the coating of the pigment with the anionic group-containing polymer can proceed simultaneously. From such a viewpoint, the solid content ratio is preferably 40% by mass or more, and more preferably 50% by mass or more.
From the viewpoint of keeping the viscosity high and constant, the kneading method described below uses a closed kneader, and the mass of the mixture during kneading is preferably 90% by mass or more with respect to the charged amount before kneading. Knead so as to be maintained in the range of.

  By increasing the amount of the pigment added to the mixture as much as possible, the pigment concentration of the non-volatile content of the kneaded product can be increased. From this point of view, the charging amount is preferably 35% by mass or more, more preferably 40% by mass or more, based on the total amount of the mixture. In addition, by increasing the amount charged, the amount of the anionic group-containing polymer charged can be relatively reduced, and the excess anionic group-containing polymer that does not contribute to the coating of the pigment can be reduced. Moreover, it is preferable that the content ratio of the said pigment and the said polymer is 10 / 0.5-10 / 20 by mass ratio, More preferably, it is 10 / 0.5-10 / 10.

  The water-soluble organic solvent is preferably used in a mass ratio of 1/5 or more, and most preferably 1/3 or more of the pigment. By using the water-soluble organic solvent in a mass ratio of 1/3 or more of the pigment, the kneading can always proceed in the presence of a certain amount of solvent from the start to the end of the kneading step. As a result, the anionic group-containing polymer is always kept in a dissolved state, and depending on the anionic group-containing polymer, the kneading process can be advanced while maintaining a semi-dissolved or swollen state. Is estimated to be performed well.

  As the water-soluble organic solvent preferably used in the kneading method, it is preferable to use a medium that does not volatilize easily, and high boiling point, low volatility, high surface tension polyhydric alcohols are preferable, especially diethylene glycol, triethylene glycol. Glycols such as are preferred.

To obtain a colorant with a stronger coating state, add a water-soluble organic solvent to the kneaded product, mix and stir to liquefy it, lower the viscosity, and disperse the pigment coated with the resin in the water-soluble organic solvent It is preferable to perform a mixing step. In the mixing step, it may be liquefied at once by adding the water-soluble organic solvent all at once, but after adding the total addition amount in portions and stirring the post-addition, the entire mixture becomes uniform. In order to realize uniform liquefaction, it is preferable to perform the subsequent stirring later. Alternatively, when the water-soluble organic solvent is added in a divided manner as described above, a small amount of the water-soluble organic solvent may be continuously added over the entire mixing process. Especially when the volume of the mixture when adding, mixing and stirring the water-soluble organic solvent is large and it takes a period for the stirred water-soluble organic solvent to be mixed uniformly, the water-soluble organic solvent is added in portions. Or continuously added in small portions.
By the addition of the water-soluble organic solvent, the solid content ratio of the mixture is lowered to become a highly viscous liquid.

(Method for producing aqueous pigment dispersion)
The kneaded product for an aqueous pigment dispersion is usually a kneaded product that is kneaded at room temperature. Usually, this aqueous pigment dispersion kneaded product is dispersed in a water-soluble solvent and / or water to produce an aqueous pigment dispersion.

(Water-soluble solvent and / or water)
The water-soluble solvent and / or water used in the present invention may be water alone or a mixed solvent composed of water and a water-soluble solvent. Examples of the water-soluble solvent include ketones such as acetone, methyl ethyl ketone, methyl butyl ketone, and methyl isobutyl ketone; methanol, ethanol, 2-propanol, 2-methyl-1-propanol, 1-butanol, 2-methoxyethanol, Alcohols such as tetrahydrofuran; 1,4-dioxane; 1,2-dimethoxyethane; and the like; amides such as dimethylformamide and N-methylpyrrolidone; And a compound selected from the group consisting of alcohols having 1 to 5 carbon atoms.
In addition, a water-soluble organic solvent that can be dissolved in water can also be used. For example, glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycol, and polypropylene glycol; diols such as butanediol, pentanediol, hexanediol, and diols similar to these; propylene laurate Glycol esters such as glycol; glycol ethers such as diethylene glycol monoethyl, diethylene glycol monobutyl, diethylene glycol monohexyl ether, propylene glycol ether, dipropylene glycol ether, and cellosolve containing triethylene glycol ether; methanol, ethanol, isopropyl alcohol , 1-propanol, 2-p Alcohols such as panol, 1-butanol, 2-butanol, butyl alcohol, pentyl alcohol, and alcohols homologous thereto; or lactones such as sulfolane; γ-butyrolactone; N- (2-hydroxyethyl) pyrrolidone, etc. Other various solvents known as water-soluble organic solvents such as lactams; glycerin and derivatives thereof can be mentioned. These water-soluble organic solvents can be used alone or in combination.
Among them, polyhydric alcohols such as glycols and diols having high boiling point and low volatility and high surface tension are preferable, and glycols such as diethylene glycol and triethylene glycol are particularly preferable.

As the disperser, known ones can be used. For example, when using a medium, a paint shaker, a ball mill, an attritor, a basket mill, a sand mill, a sand grinder, a dyno mill, a disperse mat, an SC mill, a spike mill, an agitator mill Etc. Examples of those that do not use media include ultrasonic homogenizers, nanomizers, resolvers, dispersers, and high-speed impeller dispersers. Among these, dispersers that use media are preferable because of their high dispersibility. The concentration may be adjusted with a water-soluble solvent as necessary after dispersion.
In addition, various known additives such as an alkali agent can be further blended when adjusting the aqueous pigment dispersion as required, and the addition of an alkali agent is preferable because the dispersion stability is improved.
Depending on the type of the disperser used, before performing dispersion (main dispersion) with the disperser, a water-soluble solvent is added to the aqueous pigment dispersion kneaded material as necessary, mixed, diluted, and It is preferable to adjust to a viscosity suitable for processing with a disperser (hereinafter, the viscosity-adjusted product may be referred to as a viscosity-adjusted product).
For example, when a sand mill is used, it is preferable to perform dispersion by driving the sand mill after diluting to a solid content concentration of 10 to 40 mass% and adjusting the viscosity to several tens to several hundred centipoise.

  In the present invention, for example, after kneading with a kneader equipped with the above stirring tank and stirring blade to obtain a kneaded product, a water-soluble solvent and / or water is added to the kneaded product in the stirring tank and mixed. By doing so, the viscosity can be adjusted. Therefore, the production from the kneaded product to the viscosity adjustment can be continuously performed with one apparatus, and the production efficiency can be improved. In addition, when diluting the kneaded product for aqueous pigment dispersion for viscosity adjustment, it is preferable to perform a dilution operation before dropping the kneaded product temperature in order to increase the dispersion efficiency and production efficiency. It is preferable to add warm pure water of 60 ° C. or more little by little while continuing to stir the kneaded product prepared using the kneading apparatus.

  In addition, after adjusting to a predetermined viscosity in the stirring tank, it is further taken out from the stirring tank and mixed with a water-soluble solvent to adjust the viscosity to obtain a viscosity-adjusted product, which is further diluted with a water-soluble solvent and / or water. It can also be dispersed to form an aqueous pigment dispersion.

(Water-based ink for inkjet recording)
The ink composition is obtained by further diluting the aqueous pigment dispersion obtained as described above with water, adding a binder resin, and adding a wetting agent (drying inhibitor), a penetrating agent, or other additives as necessary. In addition, an ink can be prepared. The concentration of the pigment contained in the ink composition is preferably about 2 to 10% by mass.
During ink adjustment, coarse particles cause nozzle clogging and other image characteristics, and therefore, after ink preparation, coarse particles are preferably removed by centrifugation or filtration.

(Wetting agent)
The wetting agent is added for the purpose of preventing the ink from drying. The content of the wetting agent in the ink for the purpose of preventing drying is preferably 3 to 50% by mass.
The wetting agent used in the present invention is not particularly limited, but a wetting agent that is miscible with water and can prevent clogging of the head of an inkjet printer is preferable. For example, glycerin, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol having a molecular weight of 2000 or less, propylene glycol, dipropylene glycol, tripropylene glycol, 1,3-propylene glycol, isopropylene glycol, isobutylene glycol, 1,4-butane Examples include diol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, mesoerythritol, pentaerythritol, and the like. Among them, the inclusion of propylene glycol and 1,3-butyl glycol has safety and excellent effects in ink drying properties and ejection performance.

(Penetration agent)
The penetrant is added for the purpose of improving the permeability to a recording medium and adjusting the dot diameter on the recording medium.
Examples of the penetrant include lower alcohols such as ethanol and isopropyl alcohol, ethylene oxide adducts of alkyl alcohols such as ethylene glycol hexyl ether and diethylene glycol butyl ether, and propylene oxide adducts of alkyl alcohols such as propylene glycol propyl ether.
The penetrant content in the ink is preferably 0.01 to 10% by mass.

(Surfactant)
The surfactant is added to adjust ink properties such as surface tension. The surfactant that can be added for this purpose is not particularly limited, and examples include various anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. Of these, anionic surfactants and nonionic surfactants are preferred.

  Examples of the anionic surfactant include alkylbenzene sulfonate, alkylphenyl sulfonate, alkylnaphthalene sulfonate, higher fatty acid salt, sulfate of higher fatty acid ester, sulfonate of higher fatty acid ester, higher alcohol ether. Sulfate salts and sulfonates of the above, higher alkyl sulfosuccinates, polyoxyethylene alkyl ether carboxylates, polyoxyethylene alkyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, etc. Specific examples include dodecylbenzene sulfonate, isopropyl naphthalene sulfonate, monobutylphenylphenol monosulfonate, monobutylbiphenyl sulfonate, dibutylphenylphenol disulfate. , And the like salts.

  Nonionic surfactants include, for example, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester , Polyoxyethylene glycerin fatty acid ester, polyglycerin fatty acid ester, sucrose fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene fatty acid amide, fatty acid alkylolamide, alkyl alkanolamide, acetylene glycol, oxyethylene adduct of acetylene glycol, Polyethylene glycol polypropylene glycol block copolymer, etc. Among them, polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid Preference is given to alkylolamide, acetylene glycol, oxyethylene adducts of acetylene glycol and polyethylene glycol polypropylene glycol block copolymers.

  Other surfactants include silicone surfactants such as polysiloxane oxyethylene adducts; fluorine surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and oxyethylene perfluoroalkyl ethers. Biosurfactants such as spicrispolic acid, rhamnolipid, lysolecithin and the like can also be used.

  These surfactants can be used alone or in combination of two or more. In consideration of the dissolution stability of the surfactant, the HLB is preferably in the range of 7-20. When the surfactant is added, the addition amount is preferably in the range of 0.001 to 2% by mass, more preferably 0.001 to 1.5% by mass, based on the total mass of the ink. More preferably, it is in the range of 01 to 1% by mass. When the addition amount of the surfactant is less than 0.001% by mass, the effect of adding the surfactant tends to be not obtained, and when it exceeds 2% by mass, problems such as blurring of the image are likely to occur. .

  Moreover, antiseptic | preservative, a viscosity modifier, a pH adjuster, a chelating agent, a plasticizer, antioxidant, an ultraviolet absorber etc. can be added as needed.

  The amount of the pigment in the ink for ink jet recording is preferably 10 to 30% by mass in order to secure a sufficient image density and to ensure the dispersion stability of the pigment in the ink.

(recoding media)
There is no particular limitation on the ink recording medium for ink jet recording, and an absorbent recording medium such as copy paper (PPC paper) generally used in copying machines, a recording medium having an ink absorbing layer, and ink absorption. Non-water-absorbing recording media that do not have the property, and poorly-absorbing recording media that have low ink water absorption. The ink for ink-jet recording of the present invention also has a characteristic that color developability is good particularly when recording is performed on a recording medium having an absorption layer, a non-water-absorbing recording medium, or a recording medium that is difficult to absorb.

  Examples of the absorbent recording medium include plain paper, fabric, cardboard, wood, and the like. Further, examples of the recording medium having an absorption layer include inkjet dedicated paper, and specific examples thereof include, for example, Pictrico Pro Photo Paper from Pictorico Co., Ltd.

  Examples of non-water-absorbing recording media that do not have ink absorbency include those used for food packaging materials and the like, and known plastic films can be used. Specific examples include polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyolefin films such as polyethylene and polypropylene, polyamide films such as nylon, polystyrene films, polyvinyl alcohol films, polyvinyl chloride films, polycarbonate films, polyacrylonitrile films, Examples include biodegradable films such as polylactic acid films. In particular, a polyester film, a polyolefin film, and a polyamide film are preferable, and polyethylene terephthalate, polypropylene, and nylon are more preferable. Moreover, the above-mentioned film coated with polyvinylidene chloride or the like for imparting a barrier property may be used, and if necessary, a film in which a deposited layer of a metal oxide such as aluminum or a metal oxide such as silica or alumina is used in combination. May be.

The plastic film may be an unstretched film, but is preferably stretched uniaxially or biaxially. Further, the surface of the film may be untreated, but those subjected to various treatments for improving adhesive properties such as corona discharge treatment, ozone treatment, low temperature plasma treatment, flame treatment, glow discharge treatment and the like are preferable.
The film thickness of the plastic film is appropriately changed according to the use. For example, in the case of a flexible packaging application, the film thickness is 10 μm to 100 μm as having flexibility, durability, and curl resistance. Preferably there is. More preferably, it is 10 micrometers-30 micrometers. Specific examples thereof include Pyrene from Toyobo Co., Ltd.

  Art paper such as printing paper, coated paper, lightweight coated paper, finely coated paper, and the like can be used as a recording medium having low ink water absorption and poor absorbability. These hardly absorbent recording media are those in which a coating layer is provided by applying a coating material on the surface of high-quality paper, neutral paper, etc. that are generally not surface-treated mainly composed of cellulose. Oji Paper Co., Ltd. “OK Everlight Coat” manufactured by Nippon Paper Industries Co., Ltd., “Aurora S” manufactured by Nippon Paper Industries Co., Ltd., “OK Coat L” manufactured by Oji Paper Co., Ltd., and “Aurora L” manufactured by Nippon Paper Industries Co., Ltd. , Etc. Lightweight coated paper (A3), Oji Paper Co., Ltd. “OK Top Coat +” and Nippon Paper Industries Co., Ltd. “Aurora Coat” coated paper (A2, B2), Oji Paper Co., Ltd. Art paper (A1) such as “OK Kanfuji +” manufactured by Mitsubishi and “Tokuhishi Art” manufactured by Mitsubishi Paper Industries Co., Ltd., and the like.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by a following example, unless the summary is exceeded. In the following examples, “parts” and “%” are based on mass unless otherwise specified.

(Synthesis Example 1 Synthesis Example of Polymer Represented by General Formula (1))
N-Butyllithium as a polymerization initiator and styrene as a first monomer are introduced into the T-shaped micromixer M1 in FIG. 1 from the tube reactors P1 and P2 in FIG. 1 to form a polymer by living anion polymerization. It was.
Next, the obtained polymer is moved to the T-shaped micromixer M2 in FIG. 1 through the tube reactor R1 in FIG. 1, and the growth regulator of the polymer is introduced into the reaction regulator (3) introduced from the tube reactor P3 in FIG. 1,1, -diphenylethylene).
Next, tert-butyl methacrylate is introduced as a second monomer from the tube reactor P4 shown in FIG. 1 into the T-shaped micromixer M3, and the polymer moved through the tube reactor R2 in FIG. Living anionic polymerization reaction was performed. Thereafter, the reaction was quenched with methanol to produce a block copolymer (PA-1).

  At this time, the reaction temperature was set to 24 ° C. by burying the entire microreactor in a thermostat. The monomer and reaction modifier to be introduced into the microreactor are dissolved in tetrahydrofuran (THF), and n-butyllithium is prepared by diluting a commercially available 2.6M hexane solution with hexane. The molar ratio of the polymer (PA-1) was adjusted as follows.

Mol ratio polymerization initiator of block copolymer (PA-1) / first monomer / reaction modifier / second monomer = 1.0 / 13.5 / 1.0 / 7.5

The resulting block copolymer (PA-1) was treated with a cation exchange resin to hydrolyze the t-butoxycarbonyl group of the tert-butyl methacrylate residue and convert it to a carboxyl group. The reaction solution was distilled off under reduced pressure, and the resulting solid was pulverized to obtain a polymer (P-1) powder.
The weight average molecular weight of the polymer (P-1) was 2742, and the acid value was 145 mgKOH / g.

(Synthesis Examples 2 to 12)
Polymers (P-2) to (P-12) were produced in the same manner as in Synthesis Example 1 by adjusting the monomer type and amount introduced, and are summarized in Tables 1 and 2.

In the table,
BuLi represents normal butyl lithium;
St represents styrene,
DPE represents 1,1-diphenylethylene,
tBMA represents methacrylic acid tert-butyl ester;
nBMA represents methacrylic acid n-butyl ester.

(Synthesis Example 13 Synthesis Example of Comparative Polymer)
(Method for adjusting random polymer)
100 parts of methyl ethyl ketone was charged into a reaction vessel having a stirring device, a dropping device, and a reflux device, and the inside of the reaction vessel was purged with nitrogen while stirring. After maintaining the inside of the reaction vessel in a nitrogen atmosphere and heating to reflux of methyl ethyl ketone, 74 parts of styrene, 11 parts of acrylic acid, 15 parts of methacrylic acid and a polymerization initiator (“Wako Pure Chemical Industries /“ V -75 ") 8 parts of the mixture was added dropwise over 2 hours. The temperature of the reaction system was kept at 80 ° C. during the dropping.
After completion of the dropwise addition, the reaction was continued for another 25 hours at the same temperature. In the middle of the reaction, a polymerization initiator was appropriately added while confirming the consumption status of the raw materials. After completion of the reaction, methyl ethyl ketone was distilled off under reduced pressure, and the resulting solid was pulverized to obtain a polymer (P-13) powder.
The weight average molecular weight of the polymer (P-13) was 9000, and the acid value was 185 mgKOH / g.

(Synthesis Example 14 Synthesis Example of Comparative Polymer)
(Method for preparing block polymer in which A ² and A ³ are directly linked)
In 500 mL eggplant type Schlene containing a stir bar, 200 g of propylene glycol monomethyl ether acetate (hereinafter abbreviated as PGMEA) as a solvent, 16.9 g of styrene, 2-cyanopropan-2-yl N-methyl- as a RAFT agent After adding 16 mmol of N- (pyridin-4-yl) carbamodithioate, nitrogen was bubbled into the solution in the flask at 200 mL / min for 1 minute while bubbling in the liquid. Next, the flask was placed on an 80 ° C. hot water bath, and the temperature inside the flask was raised to 80 ° C. Ten minutes after reaching 80 ° C., a solution consisting of 20 g of PGMEA and 4 mmol of a polymerization initiator 2,2′-azobisisobutyronitrile (AIBN) was fed into the flask all at once, followed by stirring for 5 hours while maintaining the temperature. The reaction solution was cooled to room temperature to stop the reaction. Next, 5.61 g of styrene and 8.1 g of acrylic acid were blown into the flask, and again placed on a 80 ° C. hot water bath, and the temperature inside the flask was raised to 80 ° C. Ten minutes after reaching 80 ° C., a solution consisting of 20 g of PGMEA and polymerization initiator AIBN 4 mmo was fed into the flask at once, and then stirred for 5 hours while maintaining the temperature. Next, a solution consisting of 20 g of PGMEA and 8 mmol of AIBN was supplied all at once into the flask, stirred for 2 hours while maintaining the temperature, and the reaction solution was cooled to room temperature to stop the reaction. The amount of residual monomer in the reaction solution at this time was quantified to determine the polymerization rate. When the molecular weight was measured by GPC, the number average molecular weight (Mn) = 2300, the weight average molecular weight (Mw) = 2875, and the dispersity (Mw / Mn) = 1.25. Moreover, it was 160 when the acid value was measured (P-14).

<Example 1>
50 parts of phthalocyanine pigment Fast Gen Blue Pigment (manufactured by DIC: CI Pigment 15: 3) and 15 parts of resin (P-1) are used in a planetary mixer PLM-V-50 (Aiko Co., Ltd.) having a capacity of 0.8 L. The jacket temperature was heated to 80 ° C. and mixed at a rotational speed of 80 rpm. Thereafter, 22 parts of diethylene glycol and 6 parts of a 34% potassium hydroxide aqueous solution were added and kneaded for 1 hour.
Subsequently, 150 parts of ion-exchanged water was gradually added to the kneaded material in the container while stirring was continued, and then a mixed solution of 29 parts of diethylene glycol and 62 parts of ion-exchanged water was added and mixed.
The aqueous pigment dispersion had a solid content concentration of 20.2% and a pigment concentration of 15.0%.

<Example 2>
50 parts of phthalocyanine pigment Fast Gen Blue Pigment (manufactured by DIC: CI Pigment 15: 3) and 15 parts of resin (P-2) planetary mixer PLM-V-50 (Aiko Co., Ltd.) The jacket temperature was heated to 80 ° C. and mixed at a rotational speed of 80 rpm. Thereafter, 22 parts of diethylene glycol and 8 parts of 34% potassium hydroxide aqueous solution were added and kneaded for 1 hour.
Subsequently, 150 parts of ion-exchanged water was gradually added to the kneaded material in the container while stirring was continued, and then a mixed solution of 29 parts of diethylene glycol and 60 parts of ion-exchanged water was added and mixed.
The aqueous pigment dispersion had a solid content concentration of 20.3% and a pigment concentration of 15.0%.

< Comparative Example 3>
50 parts of phthalocyanine pigment Fast Gen Blue Pigment (manufactured by DIC: CI Pigment 15: 3), 15 parts of resin (P-3) is a planetary mixer PLM-V-50 (Aiko Co., Ltd.) having a capacity of 0.8 L The jacket temperature was heated to 80 ° C. and mixed at a rotational speed of 80 rpm. Thereafter, 22 parts of diethylene glycol and 6 parts of a 34% potassium hydroxide aqueous solution were added and kneaded for 1 hour.
Subsequently, 150 parts of ion-exchanged water was gradually added to the kneaded material in the container while stirring was continued, and then a mixed solution of 29 parts of diethylene glycol and 62 parts of ion-exchanged water was added and mixed.
This aqueous pigment dispersion had a solid content concentration of 20.1% and a pigment concentration of 15.0%.

< Comparative example 4>
50 parts of phthalocyanine pigment Fast Gen Blue Pigment (manufactured by DIC: CI Pigment 15: 3), 15 parts of resin (P-4) is a planetary mixer PLM-V-50 (Aiko Co., Ltd.) having a capacity of 0.8 L The jacket temperature was heated to 80 ° C. and mixed at a rotational speed of 80 rpm. Thereafter, 22 parts of diethylene glycol and 6 parts of a 34% potassium hydroxide aqueous solution were added and kneaded for 1 hour.
Subsequently, 150 parts of ion-exchanged water was gradually added to the kneaded material in the container while stirring was continued, and then a mixed solution of 29 parts of diethylene glycol and 62 parts of ion-exchanged water was added and mixed.
The aqueous pigment dispersion had a solid content concentration of 20.2% and a pigment concentration of 15.0%.

<Example 5>
50 parts of phthalocyanine pigment Fast Gen Blue Pigment (manufactured by DIC: CI Pigment 15: 3), 10 parts of resin (P-1) is a planetary mixer PLM-V-50 (Aiko Co., Ltd.) having a capacity of 0.8 L The jacket temperature was heated to 80 ° C. and mixed at a rotational speed of 80 rpm. Then, 22 parts of diethylene glycol and 4 parts of 34% potassium hydroxide aqueous solution were added and kneaded for 1 hour.
Subsequently, 150 parts of ion-exchanged water was gradually added to the kneaded material in the container while stirring was continued, and then a mixed solution of 29 parts of diethylene glycol and 69 parts of ion-exchanged water was added and mixed.
This aqueous pigment dispersion had a solid content concentration of 18.4% and a pigment concentration of 15.0%.

<Example 6>
50 parts of phthalocyanine pigment Fast Gen Blue Pigment (manufactured by DIC: CI Pigment 15: 3) and 20 parts of resin (P-1) are planetary mixers PLM-V-50 (Aiko Co., Ltd.) having a capacity of 0.8 L. The jacket temperature was heated to 80 ° C. and mixed at a rotational speed of 80 rpm. Then, 22 parts of diethylene glycol and 9 parts of 34% potassium hydroxide aqueous solution were added and kneaded for 1 hour.
Subsequently, 150 parts of ion-exchanged water was gradually added to the kneaded material in the container while stirring was continued, and then a mixed solution of 29 parts of diethylene glycol and 55 parts of ion-exchanged water was added and mixed.
This aqueous pigment dispersion had a solid content concentration of 21.9% and a pigment concentration of 15.0%.

<Example 7>
50 parts of phthalocyanine pigment Fast Gen Blue Pigment (manufactured by DIC: CI Pigment 15: 3) and 15 parts of resin (P-5) are planetary mixers PLM-V-50 (Aiko Co., Ltd.) having a capacity of 0.8 L. The jacket temperature was heated to 80 ° C. and mixed at a rotational speed of 80 rpm. Then, 22 parts of diethylene glycol and 5 parts of 34% potassium hydroxide aqueous solution were added and kneaded for 1 hour.
Subsequently, 150 parts of ion-exchanged water was gradually added to the kneaded product in the container while stirring was continued, and then a mixed solution of 29 parts of diethylene glycol and 64 parts of ion-exchanged water was added and mixed.
The aqueous pigment dispersion had a solid content concentration of 20.0% and a pigment concentration of 15.0%.

<Example 8>
50 parts of phthalocyanine pigment Fast Gen Blue Pigment (manufactured by DIC: CI Pigment 15: 3) and 15 parts of resin (P-6) are planetary mixers PLM-V-50 (Aiko Co., Ltd.) having a capacity of 0.8 L. The jacket temperature was heated to 80 ° C. and mixed at a rotational speed of 80 rpm. Thereafter, 22 parts of diethylene glycol and 6 parts of a 34% potassium hydroxide aqueous solution were added and kneaded for 1 hour.
Subsequently, 150 parts of ion-exchanged water was gradually added to the kneaded material in the container while stirring was continued, and then a mixed solution of 29 parts of diethylene glycol and 62 parts of ion-exchanged water was added and mixed.
The aqueous pigment dispersion had a solid content concentration of 20.2% and a pigment concentration of 15.0%.

<Example 9>
50 parts of phthalocyanine pigment Fast Gen Blue Pigment (manufactured by DIC: CI Pigment 15: 3) and 15 parts of resin (P-7) are planetary mixers PLM-V-50 (Aiko Co., Ltd.) having a capacity of 0.8 L. The jacket temperature was heated to 80 ° C. and mixed at a rotational speed of 80 rpm. Thereafter, 22 parts of diethylene glycol and 6 parts of a 34% potassium hydroxide aqueous solution were added and kneaded for 1 hour.
Subsequently, 150 parts of ion-exchanged water was gradually added to the kneaded material in the container while stirring was continued, and then a mixed solution of 29 parts of diethylene glycol and 63 parts of ion-exchanged water was added and mixed.
This aqueous pigment dispersion had a solid content concentration of 20.1% and a pigment concentration of 15.0%.

<Example 10>
50 parts of phthalocyanine pigment Fast Gen Blue Pigment (manufactured by DIC: CI Pigment 15: 3) and 15 parts of resin (P-8) are planetary mixers PLM-V-50 (Aiko Co., Ltd.) having a capacity of 0.8 L The jacket temperature was heated to 80 ° C. and mixed at a rotational speed of 80 rpm. Then, 22 parts of diethylene glycol and 5 parts of 34% potassium hydroxide aqueous solution were added and kneaded for 1 hour.
Subsequently, 150 parts of ion-exchanged water was gradually added to the kneaded material in the container while stirring was continued, and then a mixed solution of 29 parts of diethylene glycol and 63 parts of ion-exchanged water was added and mixed.
This aqueous pigment dispersion had a solid content concentration of 20.1% and a pigment concentration of 15.0%.

<Example 11>
50 parts of phthalocyanine pigment Fast Gen Blue Pigment (manufactured by DIC: CI Pigment 15: 3) and 15 parts of resin (P-9) are planetary mixers PLM-V-50 (Aiko Co., Ltd.) having a capacity of 0.8 L The jacket temperature was heated to 80 ° C. and mixed at a rotational speed of 80 rpm. Then, 22 parts of diethylene glycol and 9 parts of 34% potassium hydroxide aqueous solution were added and kneaded for 1 hour.
Subsequently, 150 parts of ion-exchanged water was gradually added to the kneaded material in the container while stirring was continued, and then a mixed solution of 29 parts of diethylene glycol and 60 parts of ion-exchanged water was added and mixed.
The aqueous pigment dispersion had a solid content concentration of 20.4% and a pigment concentration of 15.0%.

<Example 12>
50 parts of phthalocyanine pigment Fast Gen Blue Pigment (manufactured by DIC: CI Pigment 15: 3) and 15 parts of resin (P-10) are planetary mixers PLM-V-50 (Aiko Co., Ltd.) having a capacity of 0.8 L. The jacket temperature was heated to 80 ° C. and mixed at a rotational speed of 80 rpm. Thereafter, 22 parts of diethylene glycol and 13 parts of 34% potassium hydroxide aqueous solution were added and kneaded for 1 hour.
Subsequently, 150 parts of ion-exchanged water was gradually added to the kneaded material in the container while stirring was continued, and a mixed solution of 29 parts of diethylene glycol and 56 parts of ion-exchanged water was added and mixed.
The aqueous pigment dispersion had a solid content concentration of 20.8% and a pigment concentration of 15.0%.

<Example 13>
50 parts of phthalocyanine pigment Fast Gen Blue Pigment (manufactured by DIC: CI Pigment 15: 3) and 15 parts of resin (P-11) are mixed with a planetary mixer PLM-V-50 (Aiko Co., Ltd.) having a capacity of 0.8 L. The jacket temperature was heated to 80 ° C. and mixed at a rotational speed of 80 rpm. Thereafter, 22 parts of diethylene glycol and 6 parts of a 34% potassium hydroxide aqueous solution were added and kneaded for 1 hour.
Subsequently, 150 parts of ion-exchanged water was gradually added to the kneaded material in the container while stirring was continued, and then a mixed solution of 29 parts of diethylene glycol and 62 parts of ion-exchanged water was added and mixed.
This aqueous pigment dispersion had a solid content concentration of 20.1% and a pigment concentration of 15.0%.

<Example 14>
50 parts of phthalocyanine pigment Fast Gen Blue Pigment (manufactured by DIC: CI Pigment 15: 3) and 15 parts of resin (P-12) are planetary mixers PLM-V-50 (Aiko Co., Ltd.) having a capacity of 0.8 L. The jacket temperature was heated to 80 ° C. and mixed at a rotational speed of 80 rpm. Thereafter, 22 parts of diethylene glycol and 6 parts of a 34% potassium hydroxide aqueous solution were added and kneaded for 1 hour.
Subsequently, 150 parts of ion-exchanged water was gradually added to the kneaded material in the container while stirring was continued, and then a mixed solution of 29 parts of diethylene glycol and 62 parts of ion-exchanged water was added and mixed.
The aqueous pigment dispersion had a solid content concentration of 20.2% and a pigment concentration of 15.0%.

<Comparative Example 1>
50 parts of phthalocyanine pigment Fast Gen Blue Pigment (manufactured by DIC: CI Pigment 15: 3) and 15 parts of resin (P-13) are planetary mixers PLM-V-50 (Aiko Co., Ltd.) having a capacity of 0.8 L. The jacket temperature was heated to 80 ° C. and mixed at a rotational speed of 80 rpm. Thereafter, 22 parts of diethylene glycol and 8 parts of 34% potassium hydroxide aqueous solution were added and kneaded for 1 hour.
Subsequently, 150 parts of ion-exchanged water was gradually added to the kneaded material in the container while stirring was continued, and then a mixed solution of 29 parts of diethylene glycol and 60 parts of ion-exchanged water was added and mixed.
The aqueous pigment dispersion had a solid content concentration of 20.3% and a pigment concentration of 15.0%.

<Comparative example 2>
50 parts of phthalocyanine pigment Fast Gen Blue Pigment (manufactured by DIC: CI Pigment 15: 3) and 15 parts of resin (P-14) are planetary mixers PLM-V-50 (Aiko Co., Ltd.) having a capacity of 0.8 L. The jacket temperature was heated to 80 ° C. and mixed at a rotational speed of 80 rpm. Thereafter, 22 parts of diethylene glycol and 7 parts of a 34% aqueous potassium hydroxide solution were added and kneaded for 1 hour.
Subsequently, 150 parts of ion exchange water was gradually added to the kneaded material in the container while stirring was continued, and then a mixed solution of 29 parts of diethylene glycol and 61 parts of ion exchange water was added and mixed.
The aqueous pigment dispersion had a solid content concentration of 20.2% and a pigment concentration of 15.0%.

  The following items were measured and evaluated for the aqueous pigment dispersions prepared in the examples and comparative examples. The results are shown in Tables 3 and 4.

<Volume average particle diameter>
The aqueous pigment dispersions prepared in Examples and Comparative Examples were diluted 5000 times and measured with Microtrac UPA-150 (Leeds & Northrop). The measured value was an average value measured three times.

<Number of coarse particles>
The aqueous pigment dispersions prepared in Examples and Comparative Examples were diluted 2000 times and measured with Accusizer 780APS (manufactured by International Business). The number of coarse particles was converted to the number of particles per ml of the aqueous pigment dispersion before dilution. The unit of (× 10 ⁹ particles / ml) is used for the number of particles in the table.

<Dischargeability / Color development>
In order to measure the ejection characteristics of the inkjet and the print density of the printed matter, the following aqueous inkjet recording inks for evaluation were prepared using the aqueous pigment dispersions prepared in Examples and Comparative Examples. The aqueous pigment dispersion was adjusted according to the pigment concentration of the aqueous pigment dispersion in each Example and Comparative Example in the following formulation of 100 parts in total so that the final pigment concentration was 1.2% by mass. .
Aqueous pigment dispersion Approx. 3 parts Triethylene glycol monobutyl ether 8 parts 2-pyrrolidone 8 parts Chrycerine 3 parts Surfinol 440 (manufactured by Air Products Japan) 0.5 part Pure water Remaining

Each ink jet recording ink thus prepared was tested using an ink jet printer (EM-930C manufactured by EPSON). A nozzle check pattern was printed after filling the cartridge with ink. In addition, after printing 100% of the print density in the range of 340 cm ^{2 on} one A4 sheet in single color mode, print the nozzle check test pattern again, compare the state of the nozzles before and after the test, and check if the nozzle missing increases. It was checked whether it was discharged or not.
Furthermore, the density of the printing surface with a printing density of 100% was measured with “SpectroScan” (manufactured by X-Rite) to evaluate the color development.

  In the table, PB. 15: 3 represents the phthalocyanine pigment Fast Gen Blue Pigment (manufactured by DIC: CI Pigment 15: 3).

As a result, in Examples 1 to 14 using the polymer represented by the general formula (1), a pigment dispersion and an ink having a small number of coarse particles and excellent color developability and dischargeability were obtained. Comparative Example 1 is an example using a random copolymer, but the number of coarse particles was large and the dischargeability was poor.

It is a schematic diagram of the microreactor used by this invention.

1: T-shaped micromixer M1
2: T-shaped micromixer M2
3: T-shaped micromixer M3
4: Tube reactor R1
5: Tube reactor R2
6: Tube reactor R3
7: Tube reactor P1 for pre-cooling
8: Tube reactor P2 for pre-cooling
9: Tube reactor P3 for pre-cooling
10: Tube reactor P4 for pre-cooling

Claims (10)

A water-based pigment for producing a pigment kneaded mixture at room temperature in which a mixture containing a pigment, a basic compound, and an anionic group-containing polymer is kneaded with a closed kneader and the solid content is 50 to 80% by mass In the method for producing a kneaded product for a dispersion, a polymer represented by the general formula (1) having a weight average molecular weight of 1500 to 4500 is used as the anionic group-containing polymer. Manufacturing method of kneaded material.

(1)
(In Formula (1), A ¹ represents an organolithium initiator residue, A ² represents a repeating unit of a styrene monomer and / or a vinylpyridine monomer residue, and A ³ represents (meth) acrylic acid and / or Or (repeat unit of (meth) acrylate monomer residue) Wherein the anionic group-containing polymer, and hydrolyzing the part in A ³ to produce an anionic group in the general formula (1), the production method of an aqueous pigment dispersion for kneaded product of claim 1. In the anionic group-containing polymer, the molar ratio of ^{A 2} and ^{A 3} in the general formula (1) ^{is, A 2: A 3 = 100} : 5~100: according to claim 1 or 2 in the range of 500 A method for producing a kneaded product for an aqueous pigment dispersion. The method for producing a kneaded product for an aqueous pigment dispersion according to any one of claims 1 to 3, wherein the pigment is contained in an amount of 35% by mass to 60% by mass with respect to the total amount of the mixture. The method for producing a kneaded product for an aqueous pigment dispersion according to any one of claims 1 to 4, wherein the acid value of the anionic group-containing polymer is in the range of 40 to 400 mgKOH / g. The method for producing a kneaded product for an aqueous pigment dispersion according to any one of claims 1 to 5, wherein the anionic group-containing polymer is polymerized by living polymerization using a microreactor. The method for producing a kneaded product for an aqueous pigment dispersion according to any one of claims 1 to 6, wherein kneading is performed using a kneader having a stirring tank and a stirring blade. The method for producing a kneaded product for an aqueous pigment dispersion according to claim 7, wherein the kneader is a planetary mixer. A step of obtaining an aqueous pigment dispersion kneaded material by the method for producing an aqueous pigment dispersion kneaded material according to any one of claims 1 to 8, and dispersing the aqueous pigment dispersion kneaded material in a water-soluble solvent. A method of producing an aqueous pigment dispersion. A method for producing an ink composition, wherein the aqueous pigment dispersion obtained by the method for producing an aqueous pigment dispersion according to claim 9 is diluted with a water-soluble solvent to produce an ink composition.

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