JP4156362B2 - Manufacturing method of water-based ink - Google Patents

Description

【００７７】
表１に示された結果から、実施例１〜３によれば、ニーダーの大きさや種類によらず、混合物１kgあたりの積算動力値が所定の範囲内にある場合には、各物性に優れた水系インクが得られることがわかる。また、実施例４及び５によれば、混合物１kgあたりの積算動力値を増加させても、各種物性に優れた水系インクが得られることがわかる。
【００７８】
一方、比較例１によれば、積算動力値が低い場合には、得られる水系インクにおける平均粒径、保存性及び濾過性が悪くなることがわかる。また、比較例２によれば、固形分濃度を低下させた場合には、混合物を用いて水系インクを調製することができるが、水系インク中の粒子の平均粒径が大きく、保存性及び濾過性に劣り、更には分散メディア由来の無機物の混入がある等の数多くの欠点が生じることがわかる。また、比較例３によれば、実施例１で用いられたのと同様の固形分濃度を有する混合物を用いて混合することができないことがわかる。
【００７９】
【発明の効果】
本発明の製造法によれば、混合物の組成及びニーダーの種類やその容量等による影響を受けずに、水系インクを容易に製造することができる。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a water-based ink. More specifically, the present invention relates to a method for producing a water-based ink that can be suitably used for an ink jet printer or the like.
[0002]
[Prior art]
In recent years, pigment inks have been used for inks used in inkjet printers in order to improve water resistance and light resistance. Since the pigment ink is inferior in gloss to the dye ink, it is preferable to make the particle diameter of the dispersed pigment as small as possible. From this, it is considered that the pigment particles are refined by applying a strong shearing force to the mixture having a high solid content concentration containing the pigment with a kneader.
[0003]
As the kneading machine, for example, as a method of managing the end point of the kneading when kneading a mixture with a high solid content using a kneader, (1) a method of analyzing the composition of water or the like by chemical analysis, (2) A method for examining variations in colorimetry by photoelectric colorimetry, (3) A method for examining the degree of dispersion from the spreadability of paints and inks using a particle gauge measuring instrument, and (4) A temperature at a target degree of kneading. A method of confirming in advance and setting the end point of kneading to a predetermined temperature, (5) A method of determining the degree of kneading by touching the kneaded material with five senses, for example, fingertips, and (6) A method is known in which the time required to reach the target kneading degree is examined in advance, and the time point at which the predetermined time is reached is used as the end point of kneading (see, for example, Non-Patent Document 1).
[0004]
However, in the methods (1) to (3), sampling for determination is required, and it takes time until the determination result. Therefore, the operation is complicated, and the methods (4) to (6) are performed. In the method of ▼, the degree of kneading may vary depending on the viscosity and viscoelasticity of the kneaded product, and the degree of kneading and the end point of kneading can be uniformly controlled depending on the type of kneading machine used and its capacity. Because it is difficult, there is a drawback that operator experience and know-how are required.
[0005]
In addition, in the production of inkjet inks, a method has been proposed in which when the pigment dispersion is dispersed by a sand mill, the integrated power value applied to the sand mill per kg of the pigment dispersion is 0.1 to 10 kWh (for example, Patent Document 1). See).
[0006]
However, since this method uses a sand mill, it has a drawback that it cannot be avoided that inorganic substances derived from the media are mixed into the product. In addition, this method generally cannot be processed unless the solids concentration of the pigment dispersion is about 30% by weight or less, and it may be difficult to reduce the particle size of the pigment. In addition, there is a drawback in terms of productivity, such as the need to separate the media after processing.
[0007]
[Patent Document 1]
Patent No. 2974617 [Non-Patent Document 1]
Kenji Hashimoto, “Kneading Technology”, Industrial Technology Center, published October 5, 1978, pp. 24-30 [0008]
[Problems to be solved by the invention]
An object of the present invention is to provide a method for producing a water-based ink that can easily produce a water-based ink without being affected by the composition of the kneaded product, the kind of kneader, its capacity, and the like.
[0009]
[Means for Solving the Problems]
The present invention relates to an integrated power of 0.1 kWh or more per kg of a mixture containing a pigment, a polymer having a salt-forming group (hereinafter simply referred to as “polymer”), a neutralizing agent for neutralizing the polymer, an organic solvent and water. The present invention relates to a method for producing a water-based ink in which the mixture is kneaded with the kneader that applies a value to the kneader.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
The “integrated power value per 1 kg of the mixture” referred to in the present specification means a value obtained by dividing the integrated power value detected by the integrated power meter attached to the kneader by the amount of mixture charged.
[0011]
In the present invention, first, a mixture is prepared by mixing a pigment, a polymer, a neutralizing agent for neutralizing the polymer, an organic solvent, and water. The temperature at which these components are mixed is not particularly limited, and is usually about 10 to 40 ° C.
[0012]
The pigment may be either an inorganic pigment or an organic pigment. If necessary, they can be used in combination with extender pigments.
[0013]
Examples of the inorganic pigment include carbon black, metal oxide, metal sulfide, and metal chloride. Among these, carbon black is preferable particularly for black aqueous ink. Examples of carbon black include furnace black, thermal lamp black, acetylene black, and channel black.
[0014]
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.
Examples of extender pigments include silica, calcium carbonate, and talc.
[0015]
The amount of the pigment is preferably 100 to 700 parts by weight, more preferably 200 to 600 parts by weight, and still more preferably 300 to 500 parts by weight with respect to 100 parts by weight of the resin solid content of the polymer from the viewpoint of printing density. .
[0016]
As the polymer, a water-insoluble polymer that can contain a pigment or a water-soluble polymer that can disperse the pigment can be used. Of these, water-insoluble polymers are preferred. When a water-insoluble polymer is used, an aqueous dispersion of pigment-containing polymer particles is obtained. When a water-soluble polymer is used, a pigment dispersion is obtained. Therefore, an aqueous dispersion of pigment-containing polymer particles or a pigment dispersion can be used as the aqueous dispersion of pigment.
[0017]
Examples of the polymer include a vinyl polymer having a salt forming group, a polyester polymer having a salt forming group, and a polyurethane polymer having a salt forming group. Among these polymers, vinyl polymers having a salt-forming group are preferable.
[0018]
Examples of the vinyl polymer having a salt-forming group include a polymer of one or more monomers selected from the group consisting of styrene, (meth) acrylic acid, and (meth) acrylic acid ester.
[0019]
The weight average molecular weight of the polymer is preferably 10,000 to 300,000 from the viewpoint of enhancing the durability of the ink after printing.
[0020]
Since the polymer has a salt-forming group, a neutralizing agent is used to neutralize the salt-forming group.
[0021]
As the neutralizing agent, an acid or a base can be used depending on the type of the salt-forming group. Examples of the acid include inorganic acids such as hydrochloric acid and sulfuric acid, and organic acids such as acetic acid, propionic acid, lactic acid, succinic acid, glycolic acid, gluconic acid, and glyceric acid. Examples of the base include tertiary amines such as trimethylamine and triethylamine, ammonia, sodium hydroxide, potassium hydroxide and the like.
[0022]
The amount of the neutralizing agent is not particularly limited, and is usually an amount such that the aqueous dispersion of the obtained pigment has a neutral to weak alkaline property, for example, a pH of 4.5 to 9.5, preferably 7 to 9.5. It is desirable to be. In addition, before mixing a pigment etc. and a neutralizing agent, you may neutralize the salt production | generation group of a polymer with the neutralizing agent beforehand.
[0023]
As the organic solvent, alcohol solvents, ketone solvents, ether solvents, aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents and halogenated aliphatic hydrocarbon solvents are preferable. Among them, a hydrophilic organic solvent is more preferable.
[0024]
Examples of the alcohol solvent include methanol, ethanol, isopropanol, n-butanol, tertiary butanol, isobutanol, diacetone alcohol and the like. Examples of the ketone solvent include acetone, methyl ethyl ketone, diethyl ketone, and methyl isobutyl ketone. Examples of the ether solvent include dibutyl ether, tetrahydrofuran, dioxane and the like. Examples of the aromatic hydrocarbon solvent include benzene and toluene. Examples of the aliphatic hydrocarbon solvent include heptane, hexane, cyclohexane and the like. Examples of the halogenated aliphatic hydrocarbon solvent include methylene chloride, 1,1,1-trichloroethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, and the like. Of these, acetone and methyl ethyl ketone are preferred.
[0025]
The amount of the organic solvent is preferably 20 parts by weight or more, more preferably 30 parts by weight or more, and still more preferably 50 parts by weight or more with respect to 100 parts by weight of the resin solid content of the polymer from the viewpoint of compatibility with the pigment. . Further, the amount of the organic solvent is preferably 500 parts by weight or less, more preferably 300 parts by weight or less with respect to 100 parts by weight of the resin solid content of the polymer, from the viewpoint of obtaining an effective shearing force when the mixture is kneaded. 200 parts by weight or less is more preferable. From these viewpoints, the amount of the organic solvent is preferably 20 to 500 parts by weight, more preferably 30 to 300 parts by weight, and still more preferably 50 to 200 parts by weight with respect to 100 parts by weight of the resin solid content of the polymer. .
[0026]
Examples of water include ion exchange water, distilled water, ultrapure water, and tap water. In these, ion-exchange water, distilled water, and ultrapure water are preferable.
[0027]
The amount of water is preferably 50 to 1000 parts by weight, more preferably 100 to 500 parts by weight with respect to 100 parts by weight of the organic solvent, from the viewpoint of easy compatibility with the pigment.
[0028]
The solid concentration in the mixture is preferably 50% by weight or more, more preferably 65% by weight from the viewpoint of obtaining an effective shearing force when the mixture is kneaded, and the viscosity of the resulting kneaded product becomes too high. From the viewpoint of avoiding the inability to perform uniform kneading and avoiding the kneaded material from collapsing into particles, it is preferably 80% by weight or less, more preferably 75% by weight or less. From these viewpoints, the solid content concentration in the mixture is preferably 50% by weight or more, more preferably 50 to 80% by weight, still more preferably 65 to 80% by weight, and particularly preferably 65 to 75% by weight.
[0029]
In addition, solid content in a mixture means the total amount of solid content of a pigment, a polymer, and a neutralizer.
[0030]
In the present invention, since the neutralizing agent, organic solvent and water are present in the mixture in addition to the pigment and polymer, the adsorptive power of the polymer to the pigment becomes strong at the time of kneading. It can be carried out.
[0031]
When kneading the mixture, as described in the Chemical Engineering Association edition "Chemical Engineering Handbook" revised 5th edition, Maruzen Co., Ltd., pages 917 to 919, as a kneader, there are a batch type and a continuous type, Examples of the former include a double-arm kneader, and examples of the latter include a self-cleaning kneader. Among these, a double-arm kneader is preferable from the viewpoints of product type switching, tank cleaning, and the like. The double-arm kneader includes a normal pressure type and a pressure type, and any of them can be used in the present invention.
[0032]
In addition, when a double-arm kneader is used, coarse particles may be contained in the obtained kneaded material. In this case, it is preferable that the kneaded material is further kneaded by a roll mill. As the roll mill, a two-roll mill or a three-roll mill can be used. During the kneading, water is preferably added in order to avoid aggregation due to drying of the kneaded product.
[0033]
When the mixture is charged into the kneader, each raw material constituting the mixture may be separately charged into the kneader, the mixture may be charged all at once into the kneader, or the polymer, organic solvent, water In addition, the neutralizing agent may be mixed in advance with a dispa blade or the like, and the obtained mixture and the pigment may be charged into a kneader. However, it was obtained after mixing the polymer, neutralizing agent, organic solvent and water in a kneader or mixing these raw materials in a separate container from the standpoint of polymer neutralization and pigment compatibility. It is preferable to charge the mixture into a kneader and then charge the pigment.
[0034]
When kneading using a double-arm kneader, an integrated power value of 0.1 kWh or more per kg of the mixture is applied to the double-arm kneader.
[0035]
The degree of kneading the mixture varies depending on the type and amount of the mixture, the type and capacity of the kneader, and it is difficult to determine the degree of kneading and determine the end point of kneading.
[0036]
On the other hand, as described above, when the degree of kneading is defined by an integrated power value of 0.1 kWh or more per 1 kg of the mixture, even if the kind of kneader and its capacity change, It was found that the degree of kneading can be properly managed and the end point of the kneading can be determined appropriately.
[0037]
The integrated power value per kg of the mixture is set to 0.1 kWh or more, preferably 0.5 kWh or more from the viewpoint of reducing the residual amount of coarse particles by blending the pigment and polymer. The upper limit value of the integrated power value per kg of the mixture is not particularly limited, but if it is too large, not only the effect of kneading beyond that is recognized, but also the kneading time becomes longer and the production efficiency decreases. Tend to. Therefore, from this viewpoint, the integrated power value per kg of the mixture is preferably 6.0 kWh or less. From the above viewpoint, the integrated power value per kg of the mixture is 0.1 kWh or more, preferably 0.1 to 6.0 kWh, more preferably 0.5 to 6.0 kWh.
[0038]
The kneading temperature of the mixture is preferably 50 ° C. or less, more preferably 5 to 50 ° C., still more preferably 10 to 35 ° C., and particularly preferably 10 to 25 ° C. from the viewpoint of obtaining a shear stress suitable for kneading. The kneading temperature can be controlled by, for example, the temperature of the cooling medium flowing through the jacket of the kneader and its flow rate.
[0039]
After completion of the kneading, the obtained kneaded product can be used as it is, or the kneaded product may be diluted with water and / or an organic solvent.
[0040]
When the obtained kneaded material is used in water-based ink, it is preferable to dilute with water to produce an aqueous dispersion of the pigment in order to remove the organic solvent in the post-dilution step.
[0041]
The solid content concentration of the kneaded product after dilution may be a level that can be processed in the next dispersion step, but is usually about 10 to 40% by weight.
[0042]
As an apparatus used when diluting a kneaded material with water and / or an organic solvent, a disper, a butterfly mixer, etc. are mentioned, for example.
[0043]
In addition, although the solid content contained in the obtained dilution is disperse | distributed uniformly in water and / or an organic solvent, the dispersion apparatus can be used in that case.
[0044]
Examples of the dispersing device include a high-pressure homogenizer, a ball mill, a bead mill, and a high-speed stirring type disperser. Among these, a high-pressure homogenizer is preferable because it contains less inorganic impurities.
[0045]
Examples of the high-pressure homogenizer include those having a chamber in which the flow path of the processing liquid is fixed and those having a homogeneous valve capable of adjusting the width of the flow path of the processing liquid.
[0046]
Examples of the high-pressure homogenizer having a chamber in which the flow path of the treatment liquid is fixed include, for example, a microfluidizer (trade name, manufactured by Microfluidics Co., Ltd.), a nanomizer (trade name, manufactured by Nanomizer Co., Ltd.) Machine name, product name] and the like. Moreover, as a high-pressure homogenizer having a homogeneous valve, a high-pressure homogenizer (manufactured by Runny, trade name), a high-pressure homogenizer [manufactured by Mimaru Machinery Co., Ltd., trade name], a high-pressure homogenizer [manufactured by Izumi Food Machinery Co., Ltd., Product name] and the like.
[0047]
The pressure when dispersing with a high-pressure homogenizer is preferably 50 MPa or more, more preferably 80 MPa or more, because polymer particles having a desired particle diameter can be easily obtained in a short time.
[0048]
When producing a water-based ink using the pigment aqueous dispersion thus obtained, it is preferable to remove the organic solvent from the aqueous dispersion. The method for removing the organic solvent from the pigment aqueous dispersion is preferably a vacuum distillation method, more preferably a thin film vacuum distillation method.
[0049]
If necessary, coarse particles may be removed from the pigment aqueous dispersion by centrifugation, filter filtration, or the like.
[0050]
If necessary, an aqueous ink can be obtained by adding additives such as a wetting agent, a dispersing agent, an antifoaming agent, an antifungal agent, and a chelating agent to the aqueous dispersion.
[0051]
From the viewpoint of printing density and ejection stability, the solid content in the water dispersion in the water-based ink is the polymer particles in the water dispersion of the pigment-containing polymer particles contained in the water-based ink or the pigment dispersion. It is desirable to adjust the pigment particle content to 1 to 30% by weight, preferably 2 to 15% by weight.
[0052]
【Example】
Example 1
As polymer solution, 34 parts by weight of styrene monomer, 16 parts by weight of methacrylic acid, styrene macromer [manufactured by Toa Gosei Co., Ltd., trade name: AN-6 (styrene-acrylonitrile copolymerized macromer, styrene content: 70% by weight, weight average molecular weight : 6000, synthetic functional group: methacryloyloxy group)] 15 parts by weight and octyl polyethylene glycol polypropylene glycol methacrylate [manufactured by NOF Corporation, trade name: BLEMMER 50POEP-800B] 25 parts by weight, n-butyl methacrylate [Mitsubishi Product made by Gas Chemical Co., Ltd., trade name: GE-310 (N-BMA) n-butyl methacrylate] 9.8 parts by weight and butyl acrylate [manufactured by Toagosei Co., Ltd.] 0.2 parts by weight of copolymer [initiator : 2,2'-azobis (2,4-dimethylvaleronitrile, polymerization solvent: methyl ethyl ketone, polymerization temperature: 67 ° C, polymerization time: 10 hours (dropping 3 hours, aging 7 hours) , Weight average molecular weight: 120,000] methyl ethyl ketone solution (non-evaporable component concentration: 50% by weight) was used.
[0053]
To 1.5 kg of the polymer solution, 0.17 kg of 5N aqueous sodium hydroxide solution and 1.0 kg of ion-exchanged water are added, mixed for 30 minutes with a disper blade, and charged into a 10-liter pressure kneader (manufactured by Moriyama Co., Ltd.). It is.
[0054]
Next, 3.0 kg of quinacridone pigment [Dainippon Ink Chemical Co., Ltd., trade name: Fastgen Super Magenta RG] was added thereto. The solid content concentration at that time was 67% by weight.
[0055]
The kneader was covered and sealed, and 1 ° C. cooling water was poured into the jacket and kneaded at 25 ° C. for 2 hours to obtain a kneaded product. The integrated power value per 1 kg of the mixture was 0.8 kWh.
[0056]
The resulting kneaded product (5.6 kg) was kneaded with a three-roll mill while adding ion-exchanged water (2.2 kg), then diluted with ion-exchanged water (7.2 kg) and diluted with a microfluidizer (manufactured by Microfluidics) at 200 MPa. Dispersed for 5 passes under pressure.
[0057]
After adding 3.8 kg of ion-exchanged water to the resulting dispersion treatment and stirring, the organic solvent and some water were removed at 60 ° C. under reduced pressure, and a filter with an average pore size of 5 μm (manufactured by Nippon Pole Co., Ltd.) Then, coarse particles were removed, and an aqueous dispersion of pigment-containing polymer particles having a solid content concentration of 20% by weight was obtained.
[0058]
Next, 27.5 parts by weight of an aqueous dispersion of the obtained pigment-containing polymer particles, 15.5 parts by weight of glycerin, 5 parts by weight of propylene glycol monobutyl ether, 3.5 parts by weight of triethylene glycol monobutyl ether, Surfynol 104 [Air Products Japan Co., Ltd. Product, trade name] 0.3 parts by weight and 48.2 parts by weight of ion-exchanged water were mixed to obtain a water-based ink.
[0059]
Examples 2 to 5 and Comparative Example 1
A water-based ink was produced in the same manner as in Example 1, except that the kneading conditions in Example 1 were changed as shown in Table 1.
[0060]
In addition, the kneader described in Table 1 means the following.
Kneader A: Pressurized kneader with a capacity of 10L [S10-10, manufactured by Moriyama Co., Ltd.]
Kneader B: Atmospheric pressure kneader with a capacity of 50L [Mriyama Co., Ltd., G50-25MWB-S]
Kneader C: Atmospheric pressure kneader with a capacity of 300L [TK300-100M, manufactured by Toshin Co., Ltd.]
[0061]
Comparative Example 2
To 0.179 kg of polymer solution, 0.020 kg of 5 N sodium hydroxide aqueous solution, 0.353 kg of methyl ethyl ketone and 0.591 kg of ion exchange water were added and mixed, and then quinacridone pigment [Dainippon Ink Chemical Co., Ltd., trade name: Fast Gen Super Magenta RG] 0.357 kg was added and mixed with a Disper blade for 30 minutes. The solid content at that time was 30% by weight. The mixed solution was charged into a 1.4-L sand mill (manufactured by Shinmaru Enterprises, trade name: Dino Mill) (dispersion medium: zirconia beads, filling rate: 80 vol%, disk peripheral speed: 10.5 m / sec).
[0062]
Next, this sand mill was sealed, and 1 ° C. cooling water was passed through the jacket and mixed at 25 ° C. for 3.6 hours to obtain a dispersion. The integrated power value per kg of the mixture for obtaining this dispersion was 0.8 kWh.
[0063]
To 1.500 kg of the obtained dispersion, 0.300 kg of ion-exchanged water was added for dilution, and a 5-pass dispersion treatment was performed with a microfluidizer (manufactured by Microfluidics) at a pressure of 200 MPa.
[0064]
After adding 0.450 kg of ion-exchanged water to the resulting dispersion treatment and stirring, the organic solvent and some water were removed at 60 ° C. under reduced pressure, and a filter with an average pore size of 5 μm [manufactured by Nippon Pole Co., Ltd.] Then, coarse particles were removed, and an aqueous dispersion of pigment-containing polymer particles having a solid content concentration of 20% by weight was obtained.
[0065]
Next, 27.5 parts by weight of an aqueous dispersion of the obtained pigment-containing polymer particles, 15.5 parts by weight of glycerin, 5 parts by weight of propylene glycol monobutyl ether, 3.5 parts by weight of triethylene glycol monobutyl ether, Surfynol 104 [Air Products Japan Co., Ltd. Product, trade name] 0.3 parts by weight and 48.2 parts by weight of ion-exchanged water were mixed to obtain a water-based ink.
[0066]
Comparative Example 3
In Comparative Example 2, the amount of the polymer solution was 0.397 kg, the amount of 5N aqueous sodium hydroxide solution was 0.044 kg, the amount of ion-exchanged water was 0.264 kg, quinacridone pigment [manufactured by Dainippon Ink & Chemicals, Inc. , Product name: Fastgen Super Magenta RG] was changed to 0.793 kg and mixed with a disper blade for 30 minutes in the same manner as in Comparative Example 2 except that methyl ethyl ketone was not used. It was not possible to mix in good condition.
[0067]
Next, the physical properties of the water-based inks obtained in each Example and each Comparative Example were evaluated based on the following methods. The results are shown in the table.
[0068]
(1) Average particle diameter The average particle diameter was measured using a laser particle analysis system ELS-8000 manufactured by Otsuka Electronics Co., Ltd.
[0069]
(2) Storage stability Store in a constant temperature bath at 70 ° C, and measure the viscosities after 1 day and 30 days from storage with an E-type viscometer (rotor: 8 ° 34 'x R24, 20 ° C). formula:
Viscosity retention was determined on the basis of [viscosity retention] = [viscosity after 30 days of storage] / [viscosity after 1 day of storage] × 100, and evaluated according to the following evaluation criteria.
[0070]
〔Evaluation criteria〕
○: Viscosity retention is 90% or more and less than 110% ×: Viscosity retention is 110% or more and less than 90%
(3) Productivity Since the productivity decreases as the kneading time becomes longer, the evaluation was made based on the following evaluation criteria.
[0072]
〔Evaluation criteria〕
○: Kneading time is 10 hours or less ×: Kneading time exceeds 10 hours
(4) Filterability
Filtered with a 25 mL needleless syringe (made by Terumo Corporation) equipped with a 0.8 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, made by Fuji Photo Film Co., Ltd.), one of the filters is clogged. The amount of liquid flow until measurement was measured and evaluated based on the following evaluation criteria.
[0074]
〔Evaluation criteria〕
○: The flow rate is 100 mL or more △: The flow rate is 20 mL or more and less than 100 mL ×: The flow rate is less than 20 mL [0075]
(5) Mineral contamination The inorganic (zirconium) content in the obtained water-based ink was measured by ICP (inductively coupled plasma) emission analysis (lower detection limit: 1 mg / kg).
[0076]
[Table 1]

[0077]
From the results shown in Table 1, according to Examples 1 to 3, each of the physical properties was excellent when the integrated power value per 1 kg of the mixture was within a predetermined range regardless of the size and type of the kneader. It can be seen that water-based ink can be obtained. In addition, according to Examples 4 and 5, it can be seen that water-based inks excellent in various physical properties can be obtained even when the integrated power value per 1 kg of the mixture is increased.
[0078]
On the other hand, according to Comparative Example 1, it can be seen that when the integrated power value is low, the average particle size, storage stability and filterability of the obtained water-based ink are deteriorated. In addition, according to Comparative Example 2, when the solid content concentration is lowered, a water-based ink can be prepared using a mixture, but the average particle size of the particles in the water-based ink is large, and the storage stability and filtration are reduced. It can be seen that there are a number of drawbacks, such as inferior properties and the presence of inorganic substances derived from dispersion media. Moreover, according to the comparative example 3, it turns out that it cannot mix using the mixture which has the same solid content concentration as used in Example 1.
[0079]
【The invention's effect】
According to the production method of the present invention, water-based ink can be easily produced without being affected by the composition of the mixture, the kind of kneader, its capacity, and the like.

Claims (4)

A double-arm kneader having an integrated power value of 0.1 kWh or more per 1 kg of a mixture containing a pigment, a polymer having a salt-forming group, a neutralizing agent for neutralizing the polymer having a salt-forming group, an organic solvent and water. The water-based ink is produced by kneading the mixture with the kneader and further kneading with a roll mill. The aqueous ink according to claim 1, wherein the kneaded product obtained by kneading the mixture is diluted with water and / or an organic solvent, and then the solid content derived from the kneaded product is dispersed in the obtained diluted product. Manufacturing method. The method for producing an aqueous ink according to claim 1 or 2, wherein the temperature of the mixture during kneading is adjusted to 50 ° C or lower. The method for producing a water-based ink according to any one of claims 1 to 3, wherein the solid content concentration of the mixture is 50 to 80% by weight.