JPH11181344A - Aqueous ink and method for producing the same - Google Patents

Abstract

(57) [Problem] To provide a water-based ink which can form an image having high print density, excellent light fastness and water fastness, and does not clog fine head discharge nozzles. To provide a method for producing an aqueous ink which can be produced in a short time and at low cost. SOLUTION: The method for producing an aqueous ink according to claim 6, wherein a first step of preparing a photocurable composition containing a pigment, a polymerizable substance, and a photopolymerization initiator; The method is characterized by including a second step of emulsifying in water and a third step of curing the photocurable composition emulsified in water with light.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aqueous ink and a method for producing the same, and more particularly, to a pigment-dispersed aqueous ink suitably used for an ink jet recording system and a method for producing the same.

[0002]

2. Description of the Related Art The ink jet recording method has a simpler process than other recording methods, and can record at a relatively high speed even with a device having a simple structure.
There is an advantage that a high resolution image can be obtained. In the ink jet recording system, an ink is used in which various water-soluble dyes are dissolved in water or a mixture of water and an organic solvent.

However, since this ink uses a water-soluble dye, the recorded image may bleed or disappear when the image is exposed to rain, sweat, drinking water, or the like. Was. Further, when exposed to sunlight for a long period of time, the dye is decomposed, and the color tone of the image is changed or decolored, resulting in poor light fastness.

In order to solve these problems, an ink using a pigment such as carbon black or aniline black in place of the aqueous dye has been devised, and an example in which the ink contains a water-soluble polymer is disclosed in Japanese Patent Publication No. 1-154242. Gazette, JP 58
JP-A-63766, JP-A-2-276874, and the like. If such an aqueous pigment-dispersed ink is used, the image print density, light resistance,
Water resistance and the like are improved.

[0005]

However, in these conventional water-based pigment-dispersed inks, since the pigment basically has no functional group on the surface and has little solubility, it is difficult to disperse the pigment in water. It was extremely difficult.

Therefore, a method of stirring the liquid containing the pigment for a long time has been proposed. This method makes it possible to disperse the pigment in water to some extent. Costs are high. In the initial state, even if the pigment is sufficiently dispersed, the pigment aggregates and clogs the head nozzle, or the pigment precipitates during storage for a long period of time. However, problems such as inadequate results have also occurred.

On the other hand, a method of using a dispersant to reduce the interfacial tension of water to obtain a stable dispersion state with less aggregation while making the pigment finer has been actively performed. Of ink droplets ejected from the inkjet printer, the frequency response of the ink droplets becomes poor. In the worst case, there is a problem that the ink cannot be ejected because the viscosity becomes too high. Was.

On the other hand, a hydrophobic liquid in which the pigment is easily dispersed is selected, and after the pigment is dispersed in the hydrophobic liquid,
A so-called emulsion ink obtained by preparing an oil-in-water (O / W) emulsion using an emulsifier has also been devised. However, with this ink, it is difficult to form a stable emulsion, and there is a problem that the long-term storage stability required of the ink cannot be satisfied, and practical use has been difficult.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a high print density,
It is possible to form an image with excellent light resistance and water resistance,
Another object of the present invention is to provide a method for producing an aqueous ink that does not cause clogging of fine head discharge nozzles and an aqueous ink that can be produced in a relatively short time at low cost.

[0010]

In order to achieve this object, an aqueous ink according to claim 1 is obtained by photopolymerizing a photocurable composition containing a pigment, a polymerizable substance and a photopolymerization initiator. The obtained pigment dispersion particles are dispersed in water.

Further, the aqueous ink according to the second aspect is characterized in that the aqueous ink according to the first aspect is an ink jet ink. A third aspect of the present invention is the aqueous ink according to the first or second aspect, wherein the polymerizable substance is (meth) acrylic acid or a derivative thereof.

The aqueous ink according to a fourth aspect of the present invention is the aqueous ink according to the third aspect, wherein the polymerizable substance is a mixture of two or more kinds of (meth) acrylic acid or a derivative thereof. . The aqueous ink according to a fourth aspect is the aqueous ink according to the first, second, third or fourth aspect, wherein the pigment is an organic pigment.

Here, the polymerizable substance is an oil-soluble substance,
In general, the pigment is easily dispersed, and the composition of the polymerizable substance can be adjusted so that the pigment is easily dispersed.
Further, since the pigment-dispersed particles are dispersed in water in the presence of the emulsifier, the pigment-dispersed particles are less likely to aggregate with each other, and as a result, the pigment is very well dispersed in water.

According to a sixth aspect of the present invention, there is provided a method for preparing an aqueous ink, comprising: a first step of preparing a photocurable composition containing a pigment, a polymerizable substance, and a photopolymerization initiator; Is emulsified in water, and a third step of curing the photocurable composition emulsified in water with light.

According to the method for producing an aqueous ink, a photocurable composition is prepared in the first step. In the first step, since the pigment is lipophilic, it is uniformly dispersed in the lipophilic polymerizable substance, and a photocurable composition containing the pigment, the polymerizable substance, and the photopolymerization initiator is prepared. .

Next, in the second step, the emulsion in which the lipophilic photocurable composition is emulsified and dispersed in water in the form of, for example, droplets having an average value of about 0.3 μm is obtained. Then, by the third step, when this emulsion is exposed, the photocurable composition is polymerized and cured by light to form particles, and the pigment-dispersed particles composed of a polymer in which the pigment is uniformly dispersed are dispersed in water. An aqueous ink is obtained.

Unlike the emulsion state, the pigment-dispersed particles are extremely stable even after long-term storage without changing the particle size or decomposing. Furthermore, by the function of the emulsifier, the pigment-dispersed particles do not aggregate with each other,
Well dispersed. If necessary, additives, solvents, dispersants, thickeners, and the like may be added to the aqueous ink to adjust the viscosity and the surface tension.

According to this aqueous ink production method, since the pigment-dispersed particles are produced by photopolymerization with high sensitivity, it is possible to produce the aqueous ink in a shorter time and with lower power consumption than by thermal polymerization. is there.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIGS. 1A to 1D are explanatory views schematically showing each step in the method for producing an aqueous ink of the present invention.

FIG. 1A shows a first step of preparing a photocurable composition containing a pigment, a polymerizable substance and a photopolymerization initiator.

In the first step, first, a photocurable composition comprising a polymerizable substance 14 in which a predetermined amount of pigment is uniformly dispersed and mixed in a heating vessel 11 and a solid photopolymerization initiator 15 is provided. Composition 16 is charged. Here, the mixing ratio of the pigment is
The amount is preferably 1 to 10% by weight based on the polymerizable substance, and the mixing ratio of the photopolymerization initiator is 1 to 5% by weight based on the polymerizable substance.
Is preferred.

When the proportion of the pigment is less than 1% by weight, the color becomes too light to function as an ink. When the proportion is more than 10% by weight, the pigment becomes too large and hardly hardens. The more preferable range is appropriately determined based on the light absorption of the pigment and the like. Photopolymerization initiator 1
If the ratio of 5 is less than 1% by weight, the polymerization rate in the third step becomes too slow to be efficient, and if it exceeds 5% by weight, the polymerization reaction proceeds unevenly and proceeds. Pigment dispersed particles cannot be obtained.

Prior to the first step, the pigment must be uniformly dispersed and mixed in the polymerizable substance. For this purpose, for example, using a roll mill or the like (not shown), kneading the pigment several times or several tens times the preferable amount of the polymerizable substance, and preparing a small amount of a high-viscosity master batch containing excessive pigment, and then polymerizing the master batch. Add only sexual substances
A polymerizable substance in which a pigment is dispersed at a predetermined concentration may be obtained.

Further, a preferable amount of the pigment with respect to the polymerizable substance may be dispersed and mixed as it is. In this case, a mixing and dispersing apparatus such as a super mill, a sand grinder, a bead mill, an agitator mill, a Glen mill, a Dyno mill, a pearl mill, and an attritor can be used. In the above two methods, a pigment dispersant may be used.

A heater 12 is provided around the heating vessel 11, and the polymerizable substance 14 in which the pigment is dispersed and the photopolymerization initiator 15 are heated and mixed with each other. At this time, the inside of the heating vessel 11 is simultaneously stirred and mixed at high speed by the stirrer 13, so that the polymerizable substance 14 in which the pigment is dispersed and the photopolymerization initiator 15 are uniformly mixed, and the photocurable composition 16 is Prepared.

The pigment is not particularly limited, and may be determined according to the color required for the aqueous ink to be produced. However, a pigment having good dispersibility in a polymerizable substance is particularly preferable. Organic pigments having an affinity for oily substances are preferred.

Examples of pigments for black ink include carbon blacks such as furnace black, lamp black, acetylene black and channel black, and organic pigments such as aniline black and cyanine black.

Examples of yellow color pigments include C.I. I. Pigment Yellow 1, C.I.
I. Pigment Yellow 2, C.I. I. Pi
gment Yellow 3, C.I. I. Pigmen
t Yellow 13, C.I. I. Pigment Y
yellow 16, C.I. I. Pigment Yellow
ow 83, etc., and for magenta color,
C. I. Pigment Red 5, C.I. I. Pigm
ent Red 7, C.I. I. PigmentRed
12, C.I. I. Pigment Red 48, C.I.
I. Pigment Red 112, C.I. I. Pig
Ment Red 122 and the like. For cyan color, C.I. I. Pigment Blue 1,
C. I. Pigment Blue 2, C.I. I. Pi
gment Blue 3, C.I. I. Pigment
Blue 16, C.I. I. Pigment Blue
22, C.I. I. Vat Blue 4, C.I. I. Vat
Blue 6 and the like.

These pigments may be used alone,
More than one species may be used in combination. When two or more kinds are used in combination, two or more kinds of the same color may be used in combination,
Two or more different colors may be used in combination.

As the polymerizable substance, unsaturated compounds,
For example, a compound having an ethylenically unsaturated group, a compound having an epoxy group and the like can be mentioned, and a compound having an ethylenically unsaturated group having a relatively high photopolymerization rate is preferable.

Examples of the compound having an ethylenically unsaturated group include acrylic acid and salts thereof, acrylates, acrylamides, methacrylic acid and salts thereof, methacrylates, methacrylamides, maleic anhydride, and maleic anhydride. Examples thereof include acid esters, itaconic esters, styrenes, vinyl ethers, vinyl esters, N-vinyl heterocycles, allyl ethers, allyl esters, and derivatives thereof. More preferably, acrylic acid, methacrylic acid, acrylic acid esters, methacrylic acid esters, derivatives thereof, and the like are included.

Specific examples of the acrylates include:
For example, butyl acrylate, cyclohexyl acrylate, ethylhexyl acrylate, benzyl acrylate, furfuryl acrylate, ethoxyethyl acrylate, tricyclodecanyloxy acrylate, noniphenyloxyethyl acrylate, hexanediol acrylate, 1,3-dioxolan acrylate, hexanediol diacrylate , Butanediol diacrylate, neopentyl glycol diacrylate, polyethylene glycol diacrylate, tricyclodecane dimethylol diacrylate, tripropylene glycol diacrylate, bisphenol A diacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, dipentaerythritol Caprolak Hexaacrylate of emissions adduct,
Examples include trimethylolpropane triacrylate, triacrylate of a propylene oxide adduct of trimethylolpropane, diacrylate of polyoxyethylenated bisphenol A, polyester acrylate, polyurethane acrylate, and derivatives thereof.

Specific examples of methacrylates include, for example, butyl methacrylate, cyclohexyl methacrylate, ethylhexyl methacrylate, benzyl methacrylate, furfuryl methacrylate, ethoxyethyl methacrylate, tricyclodecanyloxy methacrylate, noniphenyloxyethyl methacrylate, hexanediol Methacrylate, 1,3-dioxolane methacrylate, hexanediol dimethacrylate, butanediol dimethacrylate, neopentyl glycol dimethacrylate, polyethylene glycol dimethacrylate, tricyclodecane dimethylol dimethacrylate, tripropylene glycol dimethacrylate, bisphenol A dimethacrylate, penta Erythritol trimeta Relate, dipentaerythritol hexamethacrylate, dipentaerythritol caprolactone adduct hexamethacrylate, trimethylolpropane trimethacrylate, trimethylolpropane propylene oxide adduct trimethacrylate, polyoxyethylenated bisphenol A dimethacrylate, polyester methacrylate, Examples thereof include polyurethane methacrylate and derivatives thereof.

Among these, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, hexaacrylate of caprolactone adduct of dipentaerythritol, and hexaacrylate, trimethylolpropanetriacrylate having three or more unsaturated acryloyl groups in the molecule. It is particularly preferable to use at least one of acrylate and triacrylate of a propylene oxide adduct of trimethylolpropane. These polymerizable substances may be used alone or in combination of two or more.
It is preferable to use more than one kind in view of the fact that the polymerization reaction can be further promoted.

The above-mentioned photopolymerization initiator initiates or promotes the polymerization reaction of the above-mentioned polymerizable substance by receiving light energy, and includes, for example, aromatic carbonyl compounds, acetophenones, organic peroxides, diphenylhalonium salts, Organic halides, 2,4,6-substituted-S-triazines, 2,
4,5-triarylimidazole dimer, azo compound, dye borate complex, metal arene complex, titanocene compound and the like. These photopolymerization initiators may be used alone or in combination of two or more.

FIGS. 1B and 1C show a second step of emulsifying the photocurable composition in water. As shown in FIG. 1B, a stirrer 23 is provided inside the emulsification container 21, and a drain valve 27 is provided on a side surface of the emulsification container 21. As such an emulsifying container 21, a device called a homogenizer can be specifically used.

In the second step, first, the emulsifying vessel 21
, A liquid photocurable composition 16 and an aqueous solution 24 of an emulsifier are charged. Since the photocurable composition 16 is lipophilic, the photocurable composition 16 and the aqueous solution 24 of the emulsifier are
Separate into layers. However, it goes without saying that the upper and lower positional relationship between the layer of the photocurable composition 16 and the aqueous solution 24 of the emulsifier is determined by the relative specific gravity.

Next, as shown in FIG. 1 (c), by rotating the stirrer 23, the photo-curable composition 16 is applied with a special force to form droplets, and the droplets are formed by the action of the emulsifier in water. The droplet 25 of the photocurable composition is stabilized. That is, so-called oil-in-water droplets (O
/ W) emulsion 26 is obtained.

The diameter of the droplet 25 in the emulsion 26 is preferably 0.5 μm or less. For this purpose, conditions such as the concentration of the emulsifier and the number of rotations of the stirring are adjusted. Examples of the emulsifier to be used include commercially available nonionic and anionic polymers.

Examples of the nonionic water-soluble polymer include polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, polymethyl vinyl ether, hydroxymethyl cellulose, hydroxyethyl cellulose and the like. Examples of the anionic water-soluble polymer include, for example, sodium dodecylbenzenesulfonate, sodium alkylmethyltaurate, sodium dioctylsulfosuccinate, polystyrenesulfinic acid, polystyrenesulfonate, a copolymer of styrenesulfonic acid, and polyvinyl sulfate. , Polyvinyl sulfonate, maleic anhydride / styrene copolymer, maleic anhydride / isobutylene copolymer, and the like.
These emulsifiers may be used alone or in combination of two or more.

FIG. 1 (d) shows a third step of curing the photocurable composition emulsified in water with light.

As shown in FIG. 1D, the emulsifying vessel 2
1 is connected to the storage tank 31 via the drain valve 27 and the liquid feed pipe 34. At least a part of the liquid feed pipe 34 is made of glass, acrylic, or the like that transmits ultraviolet light and visible light.
An exposure device 32 is provided at least around a portion that transmits light. An exposure light source for exposing the emulsion 26 is provided inside the exposure device 32.

It is necessary that the emission wavelength of the exposure light source conforms to the photocuring wavelength characteristics of the photocurable composition used. The photocuring wavelength of the photocurable composition is determined by the characteristics of the photopolymerization initiator, and is usually 340 to 380n.
m in the ultraviolet range. Therefore, the exposure light source that efficiently emits light having a wavelength in this region, specifically, a fluorescent lamp or the like is preferable.

However, in the present invention, a wavelength of 380 to 7 is added by adding a wavelength sensitizing dye to the photocurable composition.
It can be adjusted so as to have high sensitivity in the visible light region of 60 nm. When such a photocurable composition is used, the exposure light source may be a visible light source. In this case, specifically, an incandescent lamp, a halogen lamp, or the like can be used.

In the third step, first, the drain valve 2
7 is opened, and the emulsion 26 is sent to the inside of the liquid sending pipe 34. Then, the emulsion 2 is exposed by the exposure device 32.
6 is exposed. At this time, since the aqueous solution 24 in the emulsion 26 is almost transparent, it transmits light and the droplet 25
Is exposed.

As a result, light is incident on the photocurable composition which is the oil droplet 25, and the photopolymerization initiator 15 in the photocurable composition is
Absorbs light, and the photopolymerization reaction of the polymerizable substance 14 proceeds,
The entire photocurable composition cures. Since the pigment is contained in the photocurable composition, pigment dispersion particles 35 in which the pigment is dispersed inside the polymer are obtained by the polymerization reaction,
A dispersion liquid 36 in which the pigment dispersion particles 35 are dispersed in the water 24 containing an emulsifier is produced.

The manufactured dispersion liquid 39 is sent to the storage tank 31 and stored in the storage tank 31 having the stirrer 33. This dispersion liquid 36 can be used as it is as an aqueous ink. However, various solvents, thickeners, dispersants, etc. are mixed to suit the ink jet device to be used, and the viscosity and surface The energy may be adjusted. In some cases, the coarse particles may be separated by a centrifugal separator to adjust the particle diameter of the pigment-dispersed particles, and then used as an aqueous ink. This water-based ink is suitably used for ink-jet recording, and can also be used for various uses such as fiber dyeing.

[0048]

EXAMPLES Example 1 A polymerizable substance was prepared by blending pentaerythritol triacrylate and dipentaerythritol hexaacrylate in a weight ratio of 1: 3, followed by mixing with a stirrer.

A phthalocyanine cyan pigment was added to the polymerizable substance, mixed with a stirrer, and kneaded with a three-roll mill for 10 passes to disperse an amount of pigment equivalent to 30% by weight based on the polymerizable substance. A mill base was prepared.

Next, the above-mentioned polymerizable substance was added to the mill base, and the pigment was adjusted to be dispersed in 3% by weight with respect to the polymerizable substance. In a laboratory in which the indoor lighting was darkened to a minimum, an acetophenone-based photopolymerization initiator Irgacure 184 (product name), which is an acetophenone-based photopolymerization initiator, was added to the pigmented polymerizable substance, and the whole was heated to 80 ° C. Stirred for 10 minutes. The composition of the photocurable composition for cyan ink thus prepared is shown. Polymerizable substance 100 parts by weight Pigment 3 parts by weight Photopolymerization initiator 3 parts by weight

Next, a 1: 1 aqueous solution of a 5% polystyrenesulfonic acid partial sodium salt aqueous solution and an 5% styrene / maleic anhydride copolymer aqueous solution as an emulsifier was prepared.
500 g of the photocurable composition and 400 g of the aqueous solution of the emulsifier were supplied to a homogenizer, and the stirrer of the four blades was rotated at a speed of 6000 rpm. As a result, an O / W emulsion in which the photocurable composition was dispersed in the form of droplets in an aqueous phase as a continuous phase was prepared.

Next, the homogenizer and the stainless steel container were connected using a transparent vinyl tube, and after opening the drain cock below the homogenizer, the emulsion was sent. At the time of this liquid sending, exposure was performed from two directions adjacent to the transparent vinyl tube with a fluorescent lamp having a total length of 40 cm and 20 W to cure the liquid droplets. Since the flow rate of the emulsion was approximately 10 m / min, the time during which a particular droplet of the emulsion was exposed was estimated to be 2.2 seconds, and in such a short time the droplet was fully cured.

After obtaining a dispersion in which the pigment-dispersed particles in which the droplets have been photocured are dispersed in the aqueous phase, the dispersion stored in the stainless steel container is subjected to centrifugal separation.
Perform processing at 2000 rpm for 15 minutes.
The above coarse particles were removed.

The particle size distribution of this dispersion was measured with a laser diffraction type particle size distribution meter, and the average particle size was 0.42 μm.
And the standard deviation was 0.14 μm. Using the dispersion, additives and the like were added as described below to obtain a cyan aqueous ink. Dispersion 30 parts by weight Glycerin 2 parts by weight Diethylene glycol 10 parts by weight N-methylpyrrolidone 5 parts by weight Isopropyl alcohol 3 parts by weight Deionized water 50 parts by weight

Example 2 A mill base for an aqueous magenta ink was prepared in the same manner as in Example 1 except that a quinacridone-based magenta pigment was used instead of the phthalocyanine-based cyan pigment. The same photopolymerization initiator as in Example 1 was used, but the composition ratio is different, so that it is shown below. Polymerizable substance 100 parts by weight Pigment 4 parts by weight Photopolymerization initiator 2.5 parts by weight

Using this photocurable composition, an emulsion was prepared in the same manner as in Example 1, followed by exposure to obtain a dispersion in which pigment-dispersed particles containing a magenta pigment were dispersed. Was. The particle size distribution of this dispersion was measured with a laser diffraction type particle size distribution analyzer, and was found to have an average particle size of 0.36 μm and a standard deviation of 0.12 μm.
Using this dispersion, additives and the like were added in the same manner as in Example 1 to obtain a magenta aqueous ink.

Example 3 A mill base for yellow ink was prepared in the same manner as in Example 1 except that an azobarium lake pigment was used instead of the phthalocyanine cyan pigment. The same photopolymerization initiator as in Example 1 was used, but the composition ratio is different, so that it is shown below. This is the composition of the photocurable composition for yellow ink prepared in this manner. Polymerizable substance 100 parts by weight Pigment 4 parts by weight Photopolymerization initiator 3 parts by weight

Using this photocurable composition, an emulsion was prepared in the same manner as in Example 1, and further exposed to light to obtain a dispersion in which pigment-dispersed particles containing a yellow pigment were dispersed. Was. After the same centrifugation treatment was performed, additives and the like were added in the same manner as in Example 1 to obtain a yellow aqueous ink.

The particle size distribution of this dispersion was measured with a laser diffraction type particle size distribution analyzer, and the average particle size was 0.49 μm.
And the standard deviation was 0.15 μm. The cyan water-based ink, magenta water-based ink, and yellow water-based ink manufactured as described above were supplied to our inkjet printers, which are prototypes, and printed on commercially available water-based inkjet paper, which clogged the nozzles. Thus, it was possible to record images favorably.

[0060]

According to the water-based ink of the first aspect, the water-based ink contains pigment-dispersed particles composed of polymer particles in which fine pigments are uniformly dispersed while being an aqueous ink. Therefore, an image recorded using this aqueous ink has a high print density, and is excellent in light resistance and water resistance. Further, since the pigment-dispersed particles are uniformly dispersed in water by the action of an emulsifier, and the pigment-dispersed particles of each other are extremely unlikely to aggregate, for example, even when used in an ink jet recording apparatus, the nozzle may be an aggregate of pigments. Ink-jet recording is performed favorably without clogging.

According to the water-based ink of the second aspect, the water-based ink of the first aspect has the above-mentioned characteristics, and is therefore most suitable as an ink for inkjet. According to the aqueous ink of the third aspect, since (meth) acrylic acid or a derivative thereof is used as the polymerizable substance, the photopolymerization reaction proceeds favorably, and the aqueous ink is more excellent in light resistance and water resistance. Becomes

According to the fourth aspect of the present invention, since a mixture of two or more kinds of (meth) acrylic acid or a derivative thereof is used as the polymerizable substance, the polymerization reaction is accelerated and the production is completed in a short time. And a cheaper aqueous ink. According to the aqueous ink of the fourth aspect, since an organic pigment is used as the pigment,
An aqueous ink containing pigment-dispersed particles in which the pigment is more favorably dispersed is obtained.

Further, according to the aqueous ink manufacturing method of the sixth aspect, the aqueous ink having the above characteristics can be obtained by a simple method in a short time. Therefore, it becomes possible to produce an aqueous recording ink having excellent characteristics in a short time and at low cost.

[Brief description of the drawings]

FIGS. 1A to 1D are explanatory views schematically showing each step in a method for producing a water-based ink of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Heating container 12 Heater 13, 23, 33 Stirrer 14 Polymerizable substance 15 Photopolymerization initiator 16 Photocurable composition 21 Emulsion container 24 Emulsifier aqueous solution 25 Droplet 26 Emulsion 27 Drain valve 31 Storage tank 32 Exposure device 34 Sending Liquid tube 35 Pigment dispersed particles 36 Dispersion

Claims (6)

[Claims] An aqueous ink, wherein pigment-dispersed particles obtained by photopolymerizing a photocurable composition containing a pigment, a polymerizable substance, and a photopolymerization initiator are dispersed in water. 2. The aqueous ink according to claim 1, wherein the aqueous ink is an inkjet ink. 3. The aqueous ink according to claim 1, wherein the polymerizable substance is (meth) acrylic acid or a derivative thereof. 4. The aqueous ink according to claim 3, wherein the polymerizable substance is a mixture of two or more of (meth) acrylic acid or a derivative thereof. 5. The pigment according to claim 1, wherein the pigment is an organic pigment.
The aqueous ink according to 3 or 4. 6. A first step of preparing a photocurable composition containing a pigment, a polymerizable substance, and a photopolymerization initiator, a second step of emulsifying the photocurable composition in water, And a third step of curing the photo-curable composition emulsified in water with light.