JP4549670B2 - Manufacturing method of water-based ink - Google Patents

Description

  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 a water-based ink for inkjet recording.

  The ink jet recording system has been widely used in recent years because it can be easily colored and can use plain paper as a recording member.

  Water-soluble dyes and polyhydric alcohols are used for inks used in ink jets in order to prevent ink from clogging the nozzles. However, this ink is inferior in water resistance and light resistance, especially when used as a heat jet ink, the dye is oxidized by the heat of the heater surface, the ink tends to scorch on the heater surface, and the discharge property is reduced. There is a drawback of doing.

  In order to eliminate this drawback, a pigment ink has been proposed. In order for the pigment ink to have stable ejection characteristics without causing clogging, it is necessary to disperse the pigment ink with a sufficiently small particle size so that the pigment does not settle in the dispersion.

  In general, the pigment is dispersed using a manufacturing method of the dispersion, and the mixing by the stirrer is usually performed at a low shear stress of about 10 Pa. However, such a low shear stress has a drawback in that poor dispersion occurs and ink characteristics deteriorate.

  In addition, a dispersion method using media by a disperser such as a bead mill, a sand mill, or a ball mill has been proposed. However, this dispersion method is not preferable in terms of function because it has a disadvantage that the amount of inorganic impurities generated by collision between the medium and the vessel or the medium is large and the discharge speed is reduced.

  In order to eliminate the above disadvantages, a method for producing a pigment ink using a high-pressure homogenizer, for example, a mixture containing at least a dispersant and a pigment is passed through a chamber having a plurality of orifices, and the treatment liquids collide with each other to make fine particles. A method for producing a pigment ink has been proposed (see, for example, Patent Document 1). This production method greatly improves the dispersion of the pigment. However, under the processing conditions in this method, since the processing pressure is low and the number of passes is small, the viscosity of the ink may change over time and stable printing may not be possible, and even more than the dispersion obtained by this method. A dispersion having good dispersion stability is desired.

Further, a method for producing a pigment ink in which a dispersion medium, a pigment, and a water-insoluble polymer are mixed and dispersed with a shear stress of 1.0 × 10 ⁵ Pa or more has been proposed (for example, see Patent Document 2). This production method greatly improves the dispersion of the pigment. However, with this method, the pigment ink is dispersed at a high processing pressure. However, the number of passes is small, and the viscosity of the ink changes over time, so that stable printing may not be possible. A dispersion having better dispersion stability than the body is desired.

  In addition, a method for producing a pigment ink has been proposed in which a mixture containing at least a dispersant and a pigment is dispersed by a liquid-wall collision type high-pressure homogenizer having a single shear line (see, for example, Patent Document 3). This production method greatly improves the dispersion of the pigment. However, with this method, the number of passes is large, but because the processing pressure is low, the viscosity of the ink may change over time, and stable printing may not be possible. The dispersion is further dispersed than the dispersion obtained by this method. A dispersion having good stability is desired.

  In addition, a method for producing a pigment ink is proposed in which a mixture containing at least a dispersant and a pigment is passed through a chamber having a plurality of orifices, and the treatment liquids collide with each other to form fine particles (see, for example, Patent Document 4). This production method greatly improves the dispersion of the pigment. However, in this method, the dispersion processing conditions at various processing pressures and various pass times are described, but this is not a condition that satisfies both the processing pressure and the pass times. The dispersion may change and may not be able to be printed stably, and a dispersion having better dispersion stability than the dispersion obtained by this method is desired.

Japanese Patent Publication No. 8-30158 JP 2002-249690 A JP-A-8-109344 JP-A-8-41395

  An object of the present invention is to provide a water-based ink having excellent dispersion stability, no clogging of the head, and excellent printing characteristics (glossiness).

The present invention relates to a water-based ink having a dispersion step in which a mixed solution of a dispersion medium, a pigment, and a water-insoluble polymer is subjected to a dispersion treatment of 9 × or more at a treatment pressure of 1.2 × 10 ⁸ Pa or more by a high-pressure homogenizer. Relates to the manufacturing method.

  The water-based ink obtained by the production method of the present invention is excellent in dispersion stability, has no clogging of the head, and has excellent printing characteristics (glossiness).

  The pigment may be either an inorganic pigment or an organic pigment. Moreover, this pigment and extender can also be used together as needed.

  Examples of the inorganic pigment include carbon black, metal oxide, metal sulfide, and metal chloride. Among these, carbon black is particularly preferable for black ink. Examples of carbon black include furnace black, thermal black, acetylene black, and channel black.

Examples of organic pigments 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.

The dispersion medium requires water and may be water alone, or water and an organic solvent may be used in combination.
Among organic solvents, alcohol solvents, ketone solvents, ether solvents, aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, and halogenated aliphatic hydrocarbon solvents are preferable.

  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 organic solvents, isopropanol, acetone and methyl ethyl ketone are preferred.

  Examples of water-insoluble polymers include water-insoluble vinyl polymers, polyester polymers, polyurethane polymers, and the like. Among these water-insoluble polymers, water-insoluble vinyl polymers are preferable. Examples of the water-insoluble vinyl polymer include a polymer of one or more monomers selected from the group consisting of styrene, (meth) acrylic acid, (meth) acrylic acid ester, and (meth) acrylic acid amide.

  The weight average molecular weight of the water-insoluble polymer is 3000 to 200,000, preferably 10,000 to 100,000, from the viewpoints of ejection properties, prevention of scorching of the printer head, durability of the ink after printing, and stability of the solution or dispersion. Is desirable.

  The water-insoluble polymer preferably has a salt-forming group and is further neutralized with a neutralizing agent from the viewpoint of dispersion stability.

  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, glyceric acid, and polyethylene glycol acid. Examples of the base include tertiary amines such as trimethylamine and triethylamine, ammonia, sodium hydroxide, potassium hydroxide and the like.

  The degree of neutralization of the water-insoluble polymer is not particularly limited, but it is usually preferable to adjust the aqueous dispersion of pigment-containing polymer particles to be neutral, for example, pH 4.5-10.

  The amount of the water-insoluble polymer is 5 to 400 parts by weight, preferably 10 to 150 parts by weight, with respect to 100 parts by weight of the pigment, from the viewpoint of printing density and ejection stability.

  Further, the amount of the dispersion medium is 100 to 2000 parts by weight, preferably 150 to 1000 parts by weight with respect to 100 parts by weight of the total amount of the pigment and the water-insoluble polymer, from the viewpoint of the viscosity of the mixture.

  In the present invention, first, a dispersion medium, a pigment, and a water-insoluble polymer are mixed. The degree of mixing of these components is not particularly limited, and these components may be simply mixed or may be mixed so as to have a uniform composition.

  In mixing, a normal mixing and stirring device such as a propeller type stirring device can be used. Among the mixing and stirring devices, a high-speed stirring and mixing device such as a disper is preferable.

  Next, the mixture of the dispersion medium, the pigment, and the water-insoluble polymer is subjected to a dispersion step. In this dispersion step, the pigment and the water-insoluble polymer are dispersed in the dispersion medium. In the dispersion step, a high pressure homogenizer is used. As a high-pressure homogenizer, a high-pressure homogenizer represented by a high-pressure homogenizer [manufactured by Izumi Food Machinery Co., Ltd., trade name], Minilab 8.3H type (manufactured by Rannie, trade name), a microfluidizer [Micro Product name], Nanomizer [product name made by Nanomizer Co., Ltd.], Optimizer [Product name made by Sugino Machine Co., Ltd.], Genus PY [Product name made by Hakusui Chemical Co., Ltd., trade name] ], A chamber-type high-pressure homogenizer such as DeBEE2000 (trade name, manufactured by Nippon BEE Co., Ltd.) and the like. Among these, a chamber-type high-pressure homogenizer is more preferable from the viewpoint of easy workability and high shear stress.

  Liquid-liquid collision type chambers and liquid-wall collision type chambers are known as dispersion chambers used in chamber-type high-pressure homogenizers.

  An example of a liquid-liquid collision type chamber is shown in FIG. As shown in FIG. 1, in the liquid-liquid collision type chamber, a plurality of liquid inflow lines 1, the same number of shear lines 2 as the inflow lines, and a single outflow line 3 are sequentially connected. The ends of the plurality of shear pipes close to the outflow pipe are connected at one place, and are dispersed by collision of the liquid flows at the connection places.

  Next, an example of a liquid-wall collision type chamber is shown in FIG. In the liquid-wall collision type chamber shown in FIG. 2, a single liquid inflow line 1, a shear line 2 and an outflow line are sequentially connected to each other, and an angle formed by the shear line and the outflow line. Is usually 45 to 135 degrees, and the liquid flow in the shearing line 3 collides with the inner wall of the outflow line. Since the chamber structure is simple, the liquid-wall collision type chamber has an advantage that the processing liquid in the chamber is less clogged and the life of the chamber is extended. Another example of the liquid-wall collision type chamber is shown in FIG. In the liquid-wall collision type chamber shown in FIG. 3, a single inflow line 1, a plurality of shear lines 2, and a single outflow line are sequentially connected, Suitable for processing.

From the viewpoint of dispersion stability of the dispersion, the dispersion treatment pressure and the number of passes are 120 × 10 ⁶ Pa or more and the number of passes is 9 or more. The dispersion treatment pressure is more preferably 150 × 10 ⁶ Pa or more. Further, the upper limit is preferably 250 × 10 ⁶ Pa or less, more preferably 220 × 10 ⁶ Pa or less, from the viewpoint of durability of the dispersion. On the other hand, the upper limit of the number of passes is 50 passes or less from the viewpoint of the durability and productivity of the dispersion, preferably 40 passes or less, more preferably 20 passes or less.

  For example, as shown in FIG. 4, the dispersion liquid passing method in the dispersion treatment is a method in which the dispersion liquid is circulated using a single dispersion tank A and a high-pressure homogenizer (the number of passes is [high-pressure homogenizer]. The volume of the dispersion liquid that has passed through the liquid is divided by the volume of the dispersion liquid that has been subjected to the dispersion treatment), and the dispersion liquid in the dispersion tank A is obtained using a high-pressure homogenizer and a plurality of dispersion tanks A and B, as shown in FIG. After the high-pressure homogenizer treatment, it is put into another dispersion tank B and once the entire amount of the dispersion liquid in the dispersion tank A is treated, the same treatment is performed from the dispersion tank B to the dispersion tank A, and then from the dispersion tank A to the dispersion tank B. And a method of repeatedly performing the process of moving the dispersion (hereinafter referred to as a catch ball method). Among these methods, the catch ball method is preferable from the viewpoint of efficient processing.

  The temperature of the dispersion during the dispersion treatment is preferably 5 ° C. or more, more preferably 10 ° C. or more from the viewpoint of suppressing the thickening of the dispersion and obtaining a stable dispersion, and also suppressing aggregation and dispersion. From the viewpoint of obtaining a dispersion having good stability, it is preferably 50 ° C. or lower, more preferably 30 ° C. or lower. From these viewpoints, the temperature of the dispersion during the dispersion treatment is preferably 5 to 50 ° C, and more preferably 10 to 30 ° C.

  When a high-pressure homogenizer is used in the dispersion step, a plurality of high-pressure homogenizers having different flow path diameters may be used to first disperse one or more passes with a high-pressure homogenizer with a large flow path diameter and then with a high-pressure homogenizer with a small flow path diameter. it can. By using such a method, blockage of the flow path of the high-pressure homogenizer having a small flow path diameter can be prevented.

As described above, the dispersion liquid, the pigment, and the mixed liquid of the water-insoluble polymer are dispersed by a high-pressure homogenizer at a treatment pressure of 120 × 10 ⁶ Pa or more and a dispersion treatment of 9 or more passes, whereby the pigment and The polymer is refined and a dispersion of pigment-containing polymer particles having a desired average particle size can be obtained.

  The average particle size of the pigment-containing polymer particles is preferably 0.05 to 1 μm, more preferably 0.05 to 0.2 μm, from the viewpoint of dispersion stability and printing characteristics. The average particle diameter is a value measured by a laser particle analysis system [ELS-8000, manufactured by Otsuka Electronics Co., Ltd.].

  When the organic dispersion is contained in the aqueous dispersion of the pigment-containing polymer particles, the organic solvent can be removed to obtain an aqueous system by vacuum distillation or the like.

  Next, an aqueous ink is obtained by adding an appropriate amount of additives such as a wetting agent, a dispersing agent, an antifoaming agent, a chelating agent, and an antifungal agent to the aqueous dispersion of the pigment-containing polymer particles as necessary. Can do.

  If necessary, additives such as a wetting agent, a dispersing agent, an antifoaming agent, a chelating agent, and an antifungal agent can be added.

Production Example 1
In a reaction vessel, 20 parts by weight of methyl ethyl ketone and 0.03 part by weight of a polymerization chain transfer agent (2-mercaptoethanol) were added, and as a monomer, styrene macromer [manufactured by Toagosei Co., Ltd., trade name: AS-6S, number average molecular weight: 6000, polymerizable functional group: methacryloyloxy group] 10 parts by weight, polyethylene glycol monomethacrylate [addition of 9 moles of ethylene oxide, manufactured by Shin-Nakamura Chemical Co., Ltd., trade name: NK ester M-90G], 10 parts by weight, polypropylene glycol mono 10 parts by weight of each of methacrylate (Aldrich Japan Co., Ltd., number average molecular weight: 375) 10 parts by weight, 12 parts by weight of methacrylic acid and 58 parts by weight of styrene monomer were mixed and thoroughly replaced with nitrogen gas. A mixed solution was obtained.

  On the other hand, the remaining 90% by weight of each monomer was charged into a dropping funnel and 0.27 parts by weight of a polymerization chain transfer agent (2-mercaptoethanol), 60 parts by weight of methyl ethyl ketone and 2,2′-azobis (2,4- Dimethylvaleronitrile) 1.2 parts by weight was added and mixed, and nitrogen gas substitution was sufficiently performed to obtain a mixed solution.

  Under a nitrogen atmosphere, the mixed solution in the reaction vessel was heated to 65 ° C. while stirring, and the mixed solution in the dropping funnel was gradually added dropwise over 3 hours. After 2 hours at 65 ° C from the end of the dropwise addition, a solution of 0.3 parts by weight of 2,2'-azobis (2,4-dimethylvaleronitrile) in 5 parts by weight of methyl ethyl ketone was added, and further at 65 ° C for 2 hours, 70 ° C. Then, 135 parts by weight of methyl ethyl ketone was added to adjust the concentration to obtain a polymer solution (hereinafter referred to as polymer A).

  A portion of the resulting polymer solution was isolated by drying at 105 ° C. under reduced pressure for 2 hours and removing the solvent. The weight average molecular weight of the obtained water-insoluble polymer having a salt-forming group was measured and found to be 74000.

[Cyan color material]
Example 1
4.8 parts by weight of Polymer A, 0.48 parts by weight of 5N aqueous sodium hydroxide solution, 1.5 parts by weight of methyl ethyl ketone, 7.6 parts by weight of ion-exchanged water, copper phthalocyanine pigment [manufactured by Dainippon Ink & Chemicals, Inc. , Trade name: TGR-SD] 2.5 parts by weight were added and mixed in a disper tank for 3 hours.

The obtained mixed liquid was subjected to dispersion under the following conditions using a chamber-type high-pressure homogenizer [manufactured by Microfluidics, trade name: Microfluidizer M-210C, Z-type chamber (liquid-wall collision type chamber)]. Obtained.
・ Processing pressure: 180 × 10 ⁶ Pa
・ Number of passes: 10 passes (catch ball method)
-Chamber orifice diameter: 87 μm

Example 2
Processing was performed in the same manner as in Example 1 except that the number of passes was 20 passes.
・ Processing pressure: 180 × 10 ⁶ Pa
・ Number of passes: 20 passes (catch ball method)
-Chamber orifice diameter: 87 μm

Example 3
Processing was performed in the same manner as in Example 1 except that the number of passes was 30.
・ Processing pressure: 180 × 10 ⁶ Pa
-Number of passes: 30 passes (catch ball method)
-Chamber orifice diameter: 87 μm

Comparative Example 1
Processing was performed in the same manner as in Example 1 except that the number of passes was processed in 3 passes.

  To each of the dispersions obtained in Examples 1 to 3 and Comparative Example 1, 35 parts by weight of ion exchange water was added and stirred, and then methyl ethyl ketone was removed at 60 ° C. under reduced pressure, and a part of the water was further removed. Thus, an aqueous dispersion of pigment-containing polymer particles having a solid content concentration of 25% by weight was obtained.

30 parts by weight of the pigment-containing polymer particle dispersion obtained, 10 parts by weight of glycerin, 7 parts by weight of propylene glycol monobutyl ether, Surfynol 465 (trade name, manufactured by Air Products Japan Ltd.), 0.3 parts by weight and ions 52.7 parts by weight of exchange water was mixed, and the resulting mixture was mixed with a 0.5 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd.) with a capacity of 25 mL without a needle. Filtration was performed with a syringe [manufactured by Terumo Corporation] to remove coarse particles to obtain a water-based ink.
The dispersion stability of the obtained water-based ink was examined. The results are shown in Table 1.

[Magenta color material]
Example 4
To 1.5 parts by weight of Polymer A, 0.17 part by weight of 5N sodium hydroxide aqueous solution and 1.0 part by weight of ion-exchanged water were added and mixed for 30 minutes with a disperser blade. Made by Moriyama Co., Ltd.].

  Next, 3.0 parts by weight 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.

  The kneader was covered and sealed, and 1 ° C. cooling water was passed through the jacket and kneaded at 25 ° C. for 2 hours to obtain a kneaded product. The integrated power value per kg of the kneaded material was 0.8 kWh.

  The resulting kneaded product was kneaded with a three-roll mill while adding 2.2 parts by weight of ion-exchanged water to 5.6 parts by weight, and then diluted by adding 7.2 parts by weight of ion-exchanged water.

A dispersion was obtained by using a chamber-type high-pressure homogenizer (trade name: Microfluidizer M-210C, Z-type chamber) manufactured by a chamber type high-pressure homogenizer.
・ Processing pressure: 200 × 10 ⁶ Pa
・ Number of passes: 10 passes (catch ball method)
-Chamber orifice diameter: 87 μm

Example 5
In Example 4, the same process as in Example 4 was performed except that the number of passes was 20 passes.
・ Processing pressure: 200 × 10 ⁶ Pa
・ Number of passes: 20 passes (catch ball method)
-Chamber orifice diameter: 87 μm

Comparative Example 2
In Example 4, the process was performed in the same manner as in Example 4 except that the number of passes was 5 passes.
・ Processing pressure: 200 × 10 ⁶ Pa
-Number of passes: 5 passes (catch ball method)
-Chamber orifice diameter: 87 μm

  After adding 15 parts by weight of ion-exchanged water to each of the aqueous dispersions obtained in Examples 4 and 5 and Comparative Example 2 and stirring, methyl ethyl ketone was removed at 60 ° C. under reduced pressure, and a part of the water was removed. As a result, an aqueous dispersion of pigment-containing polymer particles having a solid content concentration of 20% by weight was obtained.

30 parts by weight of the pigment-containing polymer particle dispersion obtained, 10 parts by weight of glycerin, 7 parts by weight of propylene glycol monobutyl ether, Surfynol 465 (trade name, manufactured by Air Products Japan Ltd.), 0.3 parts by weight and ions 52.7 parts by weight of exchange water was mixed, and the resulting mixture was mixed with a 0.5 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd.) with a capacity of 25 mL without a needle. Filtration was performed with a syringe [manufactured by Terumo Corporation] to remove coarse particles to obtain a water-based ink.
The dispersion stability of the obtained water-based ink was examined. The results are shown in Table 1.

(Yellow color material)
Example 6
Polymer A (160 parts by weight), 5N sodium hydroxide aqueous solution (0.48 parts by weight), methyl ethyl ketone (11 parts by weight), ion-exchanged water (407 parts by weight) and pigment yellow pigment (Dainippon Seika Co., Ltd., trade name: First Yellow 031) 144 parts by weight was added and mixed for 1.5 hours in a disper tank.

The obtained mixed solution was treated with a chamber type high-pressure homogenizer (trade name: Microfluidizer M-210C, Z-type chamber) manufactured by Microfluidics, Inc. in a Z-type chamber with a large orifice diameter (φ550 μm) in advance. × 10 ⁶ Pa, number of passes: A preliminary high-pressure dispersion treated by 2 passes (catch ball method) was further obtained by this dispersion under the following conditions.
・ Processing pressure: 150 × 10 ⁶ Pa
・ Number of passes: 10 passes (catch ball method)
-Chamber orifice diameter: 87 μm

Example 7
Processing was performed in the same manner as in Example 6 except that the number of passes was 20 passes.
・ Processing pressure: 150 × 10 ⁶ Pa
・ Number of passes: 20 passes (catch ball method)
-Chamber orifice diameter: 87 μm

Comparative Example 3
Processing was performed in the same manner as in Example 6 except that the number of passes was 7 passes.
・ Processing pressure: 150 × 10 ⁶ Pa
-Number of passes: 7 passes (catch ball method)
-Chamber orifice diameter: 87 μm

Comparative Example 4
The treatment was performed in the same manner as in Example 6 except that the number of passes was 10 and the dispersion pressure was 100 × 10 ⁶ Pa.
・ Processing pressure: 100 × 10 ⁶ Pa
・ Number of passes: 10 passes (catch ball method)
-Chamber orifice diameter: 87 μm

  To each of the dispersions obtained in Examples 6 to 7 and Comparative Examples 3 to 4, 240 parts by weight of ion-exchanged water was added and stirred, and then methyl ethyl ketone was removed at 60 ° C. under reduced pressure. By removing, a dispersion of pigment-containing polymer particles having a solid content concentration of 20% by weight was obtained.

  30 parts by weight of the pigment-containing polymer particle dispersion obtained, 10 parts by weight of glycerin, 7 parts by weight of propylene glycol monobutyl ether, Surfynol 465 (trade name, manufactured by Air Products Japan Ltd.), 0.3 parts by weight and ions 52.7 parts by weight of exchange water was mixed, and the resulting mixture was mixed with a 0.5 μm filter (acetylcellulose membrane, outer diameter: 2.5 cm, manufactured by Fuji Photo Film Co., Ltd.) with a capacity of 25 mL without a needle. Filtration was performed with a syringe [manufactured by Terumo Corporation] to remove coarse particles to obtain a water-based ink.

  Next, the water-based inks obtained in each Example and each Comparative Example were stored in a thermostatic bath at a temperature of 70 ° C., and the viscosities after 1 day and 30 days from storage were measured for E-type viscometer (rotor: 8 ° 34 ′ × R24, 20 ° C.). [Viscosity retention] of the water-based ink was determined based on the following formula and evaluated according to the following evaluation criteria. The results are shown in Table 1.

[Viscosity retention]
= [(Viscosity after 30 days storage) ÷ (viscosity after 1 day storage)] × 100

〔Evaluation criteria〕
○: Viscosity retention is 90% or more and 110% or less ×: Viscosity retention exceeds 110% or less than 90%

  Further, using the water-based ink obtained in Example 4, Example 5 and Comparative Example 2, solid printing was performed on commercially available MC glossy paper with an ink jet printer [Seiko Epson Corporation, model number: EM900C], 25 The glossiness was measured with a gloss meter [manufactured by Nippon Denshoku Co., Ltd., trade name: HANDYGLOSSSMETER, product number: PG-1] after being allowed to stand at 0 ° C. for 1 hour, and evaluated based on the following criteria. The results are shown in Table 1.

〔Evaluation criteria〕
○: 28 or more Δ: 25 or more and less than 28 ×: Less than 25

  From the results shown in Table 1, the inkjet recording water-based inks obtained in Examples 4 and 5 both have high gloss prints when using dedicated paper, and also have good dispersion stability. It turns out that it is excellent.

  The water-based ink obtained by the production method of the present invention can be suitably used for, for example, a water-based ink for inkjet recording.

It is a schematic explanatory drawing which shows one embodiment of the liquid-liquid collision type | mold chamber which can be used for this invention. It is a schematic explanatory drawing which shows one embodiment of the liquid-wall collision type | mold chamber with a single shear line which can be used for this invention. It is a schematic explanatory drawing which shows one embodiment of the liquid-wall collision type | mold chamber which has a some shear pipe line which can be used for this invention. In this invention, it is a schematic explanatory drawing of the method of circulating and processing a dispersion liquid with a high voltage | pressure homogenizer. In this invention, it is a schematic explanatory drawing of the method of circulating and processing a dispersion liquid with a high pressure homogenizer by a catch ball system using a some dispersion | distribution tank.

Explanation of symbols

1 Inflow line 2 Shear line 3 Outflow line

Claims (3)

A water-based ink having a dispersion step in which a mixed liquid in which a dispersion medium, a pigment, and a water-insoluble polymer are mixed is subjected to a dispersion treatment of 10 to 50 passes using a plurality of dispersion tanks at a treatment pressure of 120 × 10 ⁶ Pa or more by a high-pressure homogenizer. a manufacturing method, pass method of the dispersion in the dispersion process, the total amount of the mixed solution was treated by a high pressure homogenizer, after putting into one dispersion tank, is treated with a high pressure homogenizer the processing liquid again is a method of repeating Rukoto put to the other dispersion tank, process. High-pressure homogenizer, liquid - preparation of water-based ink of claim 1 Symbol mounting having a wall collision chamber type. Processing the preparation of water-based ink of pressure according to claim 1, wherein Ru der below 250 × 10 ⁶ Pa.

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