JP2000327968A - Colored microcapsule-dispersed aqueous jet ink - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide excellent dispersion stability, no nozzle clogging,
Further, an aqueous pigment jet ink excellent in stable inkjet discharge characteristics is obtained. The pigment comprises a pigment coated with water, a water-soluble organic solvent, and a film-forming resin having an acid value at least partially neutralized with a base. Containing a base amount equivalent to 30 to 100 mol%,
A colored microcapsule-dispersed aqueous jet ink containing an anionic surfactant comprising a naphthalene sulfonate unsubstituted or substituted with an alkyl group or an alkoxyl group and / or a fluorine-based surfactant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a colored microcapsule-dispersed aqueous jet ink.

[0002]

2. Description of the Related Art Various aqueous pigment inks having excellent safety, light fastness and water fastness have been proposed as inks for ink jet recording in the past. For example, various resin-soluble water-based inks in which carbon black or an organic pigment is dispersed using a water-soluble resin as a binder and dispersant have been proposed. However, dispersion stability, nozzle clogging, and printing on a recording medium have been proposed. The subsequent fixability and water resistance were problems.

[0003] Aqueous resin-dispersed inks have the advantage over resin-dispersed aqueous inks in that clogging of the nozzles is relatively small and that the aqueous ink is excellent in fixability and water resistance after printing on a recording medium. Specifically, JP-A-58-45272 discloses an ink composition containing a urethane polymer latex containing a dye, and JP-A-62-95366 dissolves a polymer and an oil-based dye in a water-insoluble organic solvent. Furthermore, an ink containing a dye encapsulated in polymer particles by evaporating the solvent after mixing and emulsifying with an aqueous solution containing a surfactant has been proposed. Japanese Patent Application Laid-Open No. 62-254833 discloses an organic solvent used for encapsulation. Interfacial tension between water and water is 10
There has been proposed a method for producing an aqueous suspension of a coloring agent by reducing the content to less than dyne, and JP-A-1-170672 proposes a recording liquid containing a macroencapsulated dye. The dispersion stability of the obtained colored resin dispersion was not always sufficient.

As a resin-dispersed water-based ink, Japanese Patent Application Laid-Open
No. 0-140065 discloses an anionic microencapsulated pigment obtained by coating a pigment with an organic polymer compound having an anionic group and a water-soluble anionic surfactant and / or HLB (hydrophilic lipophilic balance) value. Aqueous recording liquids containing 14 or more nonionic surfactants have been proposed and have excellent pigment dispersion stability, but the piezo method or thermal jet method has not always been sufficient in ejection stability.

Japanese Patent Application Laid-Open No. 57-90 discloses a low surface tension aqueous pigment ink having improved stable ink ejection and wetting.
No. 070 discloses an aqueous jet printing ink containing a water-soluble wetting agent, a colorant, and water as main components, wherein a perfluoroalkyl sulfonate is added to the jet printing ink, and other fluorine-containing surfactants are used. Examples of the ink composition used include JP-A-4-21478, JP-A-5-2304409, and JP-A-6-200200.
However, when the colorant is a pigment, there are problems in pigment dispersion stability and fixability to a recording medium.

[0006]

An object of the present invention is to provide a colored microcapsule-dispersed aqueous jet ink which is excellent in dispersion stability, has no nozzle clogging, and is excellent in stable ink jet discharge characteristics. Is to do.

[0007]

The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that water, a water-soluble organic solvent, and an acid at least partially neutralized with a base. A pigment coated with a film-forming resin having a specific value, the acid value of the film-forming resin in a specific range, a base amount corresponding to the neutralization ratio in the specific range, and a specific chemical structure The problem described above has been solved by combining a surfactant. The water-soluble organic solvent contains a penetrant, an anti-drying agent, and the like.

That is, the present invention comprises a pigment coated with water, a water-soluble organic solvent, and a film-forming resin having an acid value at least partially neutralized with a base, The acid value is 100 or more and less than 180, and 30 to 100
Characterized in that it contains an anionic surfactant comprising a naphthalene sulfonate salt containing an unsubstituted or substituted alkyl group or alkoxyl group, and / or a fluorine-based surfactant. Colored microcapsule-dispersed aqueous jet ink.

The anionic surfactant comprising an unsubstituted or substituted with an alkyl group or an alkoxyl group, a naphthalene sulfonate in the aqueous ink composition of the present invention has a good effect on the pigment of the colored microcapsules and the coating resin. The compound exhibits a wetting effect, and a compound having 2 to 6 carbon atoms in the alkyl group or the alkoxy group and having 1 to 2 substitutions with respect to the naphthalene skeleton exhibits a more excellent effect.

Specifically, there are the following compounds. Of course, it is not limited to this. Compound 1 Potassium propyl-naphthalenesulfonate Compound 2 Sodium butyl-naphthalenesulfonate Compound 3 Sodium dibutyl-naphthalenesulfonate Compound 4 Sodium hexyl-naphthalenesulfonate

Compound 5 Sodium propoxy-naphthalenesulfonate Compound 6 Potassium butoxy-naphthalenesulfonate Compound 7 Sodium dibutoxy-naphthalenesulfonate Compound 8 Sodium hexyloxy-naphthalenesulfonate

As the fluorine-based surfactant in the aqueous ink composition of the present invention, known and commonly used ones can be used, and more preferably, a compound having the following general formula (A) and / or (B) is used. In some cases, it has a good wetting effect on pigments and coating resins of colored microcapsules, but when combined with anionic surfactants consisting of unsubstituted or alkyl- or alkoxyl-substituted naphthalene sulfonates It shows stable ink ejection characteristics.
In any case, such as a mixture of the compounds of the general formula (A), a mixture of the compounds of the general formula (B), or a mixture of the compound of the general formula (A) and the compound of the general formula (B) Also exhibit stable ink ejection characteristics when combined with an anionic surfactant comprising naphthalene sulfonate unsubstituted or substituted with an alkyl group or an alkoxyl group.

Fluorinated surfactant: General formula (A)

Embedded image m = 1 to 6, n = 4 to 12, r = 1 to 20 Specifically, there are the following compounds.

Compound 9

Embedded image

Compound 10

Embedded image

Compound 11

Embedded image

Fluorinated surfactant: General formula (B)

Embedded image m = 3 to 20, n = 4 to 12 Specifically, there are the following compounds.

Compound 12

Embedded image

Compound 13

Embedded image

The combination of an anionic surfactant comprising the above-mentioned unsubstituted or substituted naphthalenesulfonate substituted with an alkyl group or an alkoxyl group in the aqueous ink composition of the present invention and a fluorine-based surfactant further enhances the present invention. Ink ejection stability can be obtained.

The content of the above surfactant in the ink is as follows:
Even when using each alone or in combination of both, 0.01
10 to 10% by mass, more preferably 0.1 to 5% by mass. In the present invention, the film-forming resin used for coating the pigment has an acid value of 100 or more and less than 180.
The acid value refers to the number of milligrams (mg) of potassium hydroxide (KOH) required to neutralize 1 g of the resin.
Expressed in KOH / g (hereinafter, units are abbreviated).

The molecular weight range of the film-forming resin is not particularly limited, but is preferably in the range of 10,000 to 100,000 in terms of weight average molecular weight. If the molecular weight of the film-forming resin is less than 10,000, a sufficient film cannot be formed in many cases.
This is unsuitable because nozzle clogging is likely to occur due to aggregation of microcapsule particles. In particular, in order to sufficiently coat the pigment with the film-forming resin, the molecular weight of the resin must be 1
It is preferably from 10,000 to 100,000. In addition, when the molecular weight is 100,000 or more, problems arise in solubility and the like.

The preferred film-forming resin of the present invention is a styrene resin or a (meth) acrylic resin, for example, at least one monomer selected from the group consisting of styrene, substituted styrene and (meth) acrylate. A self-water-dispersible resin obtained by at least partially neutralizing a copolymer with (meth) acrylic acid with a base is exemplified. (Meth) acrylic acid is a general term for acrylic acid and methacrylic acid, and in the present invention, either one may be essential, but more preferred film-forming resins are both acrylic acid and methacrylic acid. Having a structure derived from

That is, the self-water-dispersible resin as a preferable film-forming resin is styrene, substituted styrene, (meth)
A copolymer of acrylic acid and methacrylic acid, containing as a main component at least one monomer selected from the group consisting of acrylic acid esters, in which methacrylic acid is copolymerized more than acrylic acid; It is a neutralized self-water dispersible resin.

The self-water-dispersible resin as a more preferable film-forming resin is a copolymer of acrylic acid and methacrylic acid containing a styrene monomer as a main component. Most preferably, the monomer mass ratio of styrene / acrylic acid / methacrylic acid is in the range of 69 to 85% / 5 to 15% / 10 to 16%.

To make the resin having an acid value dispersible in an aqueous medium by neutralization, a base may be added. Examples of the base include hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide and lithium hydroxide, basic substances such as ammonia, triethylamine and morpholine, as well as triethanolamine, diethanolamine and N-methyldiethanolamine. Alcohol amines can be used.

However, if a higher acid value resin is neutralized with a stronger base, the solubility of the film-forming resin in the ink increases, and the strength and amount of the base (neutralization rate) are increased. ) Is preferably adjusted. In inkjet recording, there is very little adverse effect on nozzle clogging, dispersion stability during storage, and water resistance of printed matter.
Alcoholamines, which are weak bases, especially triethanolamine, are the best bases.

In the present invention, the neutralization ratio of the film-forming resin with respect to the acid groups is desirably 30 mol% to 100 mol%. When the neutralization ratio is equal to or less than 30 mol%, the particle size at the time of encapsulation becomes large, and the dispersion becomes unstable.
When the content is more than 100 mol%, fine particles are formed, but the resin is dissolved, and the quality of the ink itself deteriorates. More preferably, the degree of neutralization is equivalent to 40 mol% to 60 mol%. It is particularly preferable to use an unsubstituted or alkyl group or an alkoxyl group when the neutralization ratio of the film-forming resin with respect to the acid groups is from 40 to 60 mol% using an alcohol amine, particularly ethanolamine, as a base. By using an anionic surfactant composed of a naphthalene sulfonate substituted with a group and / or a fluorine-based surfactant, a remarkably excellent ink ejection stabilizing effect can be obtained.

The pigment used in the colored microcapsule-dispersed aqueous jet ink of the present invention is not particularly limited, and any known and commonly used pigment can be used.
For example, inorganic pigments such as carbon black, titanium black, titanium white, zinc sulfide and red iron oxide, azo pigments such as phthalocyanine pigments, monoazo and disazo pigments, and organic pigments such as phthalocyanine pigments and quinacridone pigments are used. When a color image is obtained, it is preferable to use a chromatic pigment as the ink.

The amount of the pigment to be used is not particularly limited as long as the effects of the present invention can be achieved, but it is preferable to adjust the amount of the pigment to usually 0.5 to 20% by mass in the ink finally obtained. Further, a water-soluble organic solvent known as an anti-drying agent or a penetrant can be used for the ink as needed.

The anti-drying agent has a property of preventing the ink from drying at the jet nozzle of the ink jet, and usually has a boiling point higher than that of water. As the water-soluble organic solvent, any of conventionally known and commonly used ones can be used. For example, polyhydric alcohols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, and glycerin can be used. There is.

In particular, glycerin is bonded to the film-forming resin on the surface of the microcapsule particles by strong hydrogen bonding to enhance the dispersion stability of the microcapsule particles, and at the same time, even if a small amount of the film-forming resin is dissolved in the ink. On the other hand, it is more preferable in terms of preventing drying at the nozzle end face by binding with a strong hydrogen bond.

The amount of the anti-drying agent is 1 to 1 with respect to the ink.
A range of 80% by weight is preferred.

The penetrant controls the penetration of the ink into the recording medium and the adjustment of 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.

In particular, 1 to 3 moles of a propylene oxide adduct of a lower alcohol having 2 to 4 carbon atoms may be used in combination with the above-mentioned anionic surfactant comprising a naphthalene sulfonate substituted with an unsubstituted or substituted alkyl or alkoxyl group. In combination with the surfactant, more excellent wettability and ink ejection stability can be obtained.

Specifically, there are the following compounds. Compound 14 Propanol oxide 1 mol adduct of propanol

Embedded image

Compound 15 2-mol adduct of propylene oxide with butanol

Embedded image

The amount of the penetrant added is 0.1
A range from 10 to 10% by mass is preferred.

As a specific method for obtaining the colored microcapsule-dispersed aqueous jet ink of the present invention, the following method is preferred when a pigment is coated using a film-forming resin having an acid value. According to this method, the resin and the component derived from the pigment dispersed in the aqueous medium consist of only colored microcapsules, and free pigment particles not covered with the film-forming resin or film-forming materials containing no pigment. It is possible to easily obtain an extremely small amount of ink containing no resin-containing particles or no dissolved film-forming resin at all. Further, the combination of the fluorine-based surfactant in the aqueous ink composition of the present invention and the above-mentioned unsubstituted or anionic surfactant comprising a naphthalene sulfonate substituted with an alkyl group or an alkoxyl group makes it possible to obtain a more excellent ink. Discharge stability is obtained. Furthermore, if a water-soluble organic solvent is added as a wetting agent, the ink ejection stability will be further improved.

The method for obtaining the colored microcapsule-dispersed aqueous jet ink of the present invention is described in, for example, the following (1) to (5).
In this order. (1) Kneading step: A pigment is dispersed in a film-forming resin having an acid value to obtain a solid colored compound.

In this step, the pigment is uniformly dissolved or dispersed in the resin in a solution or a heated and melted state by using a kneading device such as a roll, a kneader, or a bead mill, which is conventionally known, and the pigment is finally dissolved. By removing the mixture as a solid kneaded material (solid colored compound).

In particular, when it is necessary to finely disperse the pigment in the resin, as a means for dispersing the pigment, one of the dispersion methods known in the art, which can form a state where a relatively high shear force is applied, is used. It is preferable to perform dispersion under high shearing force using a means, specifically, two rolls.

(2) Suspension step: at least water, an organic solvent capable of dissolving the film-forming resin, a base, and the solid coloring compound are mixed, and a pigment suspension in which at least a part of the resin is dissolved by dispersion is dispersed. Obtain a liquid.

The organic solvent that dissolves the film-forming resin functions as a good solvent for the resin, and the organic solvent can be appropriately selected for the resin. For example, acetone, dimethyl ketone, Ketone solvents such as methyl ethyl ketone, alcohol solvents such as methanol, ethanol and isopropyl alcohol, chlorine solvents such as chloroform and methylene chloride, aromatic solvents such as benzene and toluene, ester solvents such as ethyl acetate and ethylene glycol As long as the resin can be dissolved, a glycol ether solvent such as monomethyl ether or ethylene glycol dimethyl ether can be used.

The dispersion medium used in this step is mainly water that functions as a poor solvent for the film-forming resin.
Since it is used as an aqueous ink for inkjet recording, it preferably has a purity higher than that of ion-exchanged water.

In this step, it is preferable that the mixture of water and the organic solvent is uniform. If not, a surfactant may be used or O / W may be mechanically performed, if necessary.
It is preferable to emulsify the mixture in a mold or use it in combination with a co-solvent to make it uniform. Surfactants, if used, should be kept to a minimum.

As the organic solvent for forming the dispersion medium and dissolving the resin used as required, only the organic solvent may be used. However, only the organic solvent and water and the base are used, and the pigment suspension having excellent dispersion stability is used. If it is difficult to obtain a turbid liquid, a hydrophilic organic solvent may be used in combination with the resin as a cosolvent to provide better emulsion stability. The organic solvent and the co-solvent that dissolve the resin may be used alone or in combination of two or more.

When the film-forming resin is a copolymer of (meth) acrylic acid and at least one monomer selected from the group consisting of styrene, substituted styrene and (meth) acrylic acid ester, for example, methyl ethyl ketone or the like is used. And at least one combination selected from alcohol solvents such as isopropyl alcohol as cosolvents.

The ratio of water to the organic solvent is not particularly limited as long as the effects of the present invention can be achieved, but is preferably such that the weight ratio of water / organic solvent is 10/1 to 1/1. By this step, the film-forming resin having an acid value, which is present on the surface of the solid colored compound, is gradually neutralized by a base at least partially or entirely with the acid value, and from the solid form of the compound, The mixture becomes a suspension.

As a stirring method for obtaining a suspension, any known and commonly used method can be employed. For example, in addition to a conventional uniaxial propeller-type stirring blade, a stirring blade having a shape suitable for the purpose or a stirring blade may be used. It can usually be easily suspended using a container.

When a suspension is obtained, fine mixing cannot be achieved by simple mixing and stirring in which a large shear force does not act.
When the pigment is relatively easily aggregated, a high shear force may be further applied to stabilize the fine particles. As a dispersing machine in this case, for example, a high-pressure homogenizer, a beadless dispersing machine known by trade names such as a microfluidizer and a nanomizer are preferably used because reaggregation of the pigment is small.

(3) Reprecipitation step: The film-forming resin component dissolved in the pigment suspension is deposited on the pigment surface to obtain microcapsules.

This step is a step of depositing the dissolved resin component and the dispersed resin component present in the suspension on the surface of the pigment in the pigment suspension obtained in the suspension step. The “re-precipitation” in this step does not mean that the pigment or the particles in a semi-capsule state in which the dissolved resin or the dispersed resin is adsorbed on the pigment surface is separated and settled from the liquid medium of the suspension. Therefore, what is obtained in this step is not a mere mixture in which the solid component and the liquid component are clearly separated, but the microcapsules in which the dissolved resin or the dispersed resin is coated on the pigment surface are stably used in the liquid medium of the suspension. An aqueous dispersion of dispersed colored resin particles (colored microcapsules).

The deposition of the resin on the surface of the microcapsules in the pigment suspension in the suspension step is performed, for example, at least partially on the pigment suspension in which the film-forming resin is dissolved and / or dispersed. It can be easily carried out by adding water or an aqueous medium functioning as a poor solvent to the resin and / or by removing the organic solvent from the pigment suspension.

However, a method in which water or an aqueous medium that functions as a poor solvent for the resin is further added to the pigment suspension is preferable because it causes less aggregates. In the reprecipitation, by dropping water or an aqueous medium while the suspension is gently stirred, it is possible to reliably deposit (reprecipitate) the resin on the pigment surface while preventing the generation of aggregates.

Thus, the above (1) kneading step (2)
The colored resin particles having a desired particle diameter are obtained by the resuspension step (3) reprecipitation step.
It is 0.01 to 1 μm.

(4) Desolvation step: Removal and / or concentration of the low-boiling organic solvent from the microcapsule dispersion obtained in the reprecipitation step The aqueous dispersion of colored resin particles obtained in the reprecipitation step is used as it is. However, the colored resin particles are often swollen due to the coexisting organic solvent, so that the storage stability can be further improved, or the safety against fire and pollution can be further improved. It is preferable to remove the solvent.

The dispersion thus obtained is usually provided with colored microcapsules in which a pigment is coated with a film-forming resin,
It consists essentially of a dispersion medium only. The content of the colored microcapsules in the dispersion is usually from 10 to 40% by mass based on the total amount of the microcapsules and the dispersion medium.

(5) Ink Step The aqueous dispersion of colored resin particles of submicron order, which contains no or almost no liquid medium other than water, obtained by the above step, is basically used for ink jet recording. Although it can be used as an aqueous ink, it is preferable to further adjust the ink in consideration of dispersion stability and ejection characteristics. In order to avoid nozzle clogging due to coarse particles, the coarse particles are usually removed by centrifugation or filter filtration after the solvent removal step (4), or after the ink preparation in the ink step (5). Filter with a filter having a particle size of.

The adjustment of the ink includes, for example, addition of the above-mentioned anti-drying agent and penetrant, concentration adjustment and viscosity adjustment, pH adjusting agent, surfactant other than the present invention, preservative, chelating agent, plasticizer, oxidizing agent and the like. Inhibitors, ultraviolet absorbers and the like can be added as needed.

In the case where the recording medium is other than impervious recording medium such as glass, metal, and film (penetrable recording medium), the film-forming resin is not affected so as not to affect the jetting stability. Other water-soluble resins and water-dispersible resins different from those described above can also be added.

The water-soluble organic solvent containing the anti-drying agent and the penetrant of the present invention, the surfactant, and other additives are added at the time of the addition in the most effective step among the above-mentioned steps. You just have to select The colored microcapsule-dispersed aqueous jet ink of the present invention enables extremely stable ink discharge in a printer of a known and common inkjet recording system such as a piezo system, a thermal system, or an on-demand system.

[0063]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention includes the following embodiments.

1. Water, a water-soluble organic solvent, and a pigment coated with a film-forming resin having an acid value at least partially neutralized with a base, wherein the acid value of the film-forming resin is 100 or more and less than 180, It contains an anionic surfactant comprising a naphthalene sulfonate which is unsubstituted or substituted with an alkyl group or an alkoxyl group, and / or contains a fluorine-based surfactant which contains a base amount equivalent to 30 to 100 mol%. A colored microcapsule-dispersed aqueous jet ink, characterized in that:

2. Water, a water-soluble organic solvent, and a pigment coated with a film-forming resin having an acid value at least partially neutralized with an alcoholamine, wherein the acid value of the film-forming resin is 100 or more and less than 180, 40-60 mol%
A colored microcapsule containing a considerable amount of an alcohol amine and containing an anionic surfactant and / or a fluorine-based surfactant made of unsubstituted or substituted with an alkyl group or an alkoxyl group, a naphthalene sulfonate. Dispersion type aqueous jet ink.

3. Anionic surfactant having 2 to 2 carbon atoms
A naphthalene sulfonate substituted by 1 to 2 with an alkyl group or an alkoxyl group of No. 6
3. The colored microcapsule-dispersed aqueous jet ink described in 2. and 2.

4. 4. The colored microcapsule-dispersed aqueous jet ink according to 1.2 or 3, wherein the fluorine-based surfactant is a compound having the following general formula (A) and / or (B).

Fluorinated surfactant: General formula (A)

Embedded image m = 1-6, n = 4-12, r = 1-20

Fluorinated surfactant: General formula (B)

Embedded image m = 3-20, n = 4-12 5. 5. The colored microcapsule-dispersed aqueous jet ink as described in 1, 2, 3, or 4, which contains, as a water-soluble organic solvent, a 1 to 3 mol adduct of propylene oxide of a lower alcohol having 2 to 4 carbon atoms.

The preferred embodiment of the present invention will be described below by taking as an example a case where the present invention is applied to an ink for ink jet recording.

(1) Acid value based on carboxyl group: 100
A pigment is dispersed in a film-forming styrene- (meth) acrylic acid copolymer resin having a weight-average molecular weight of 10,000 to 100,000 having a weight average molecular weight of less than 180 using a two-roll mill to obtain a solid colored compound.

(2) Methyl ethyl ketone is mainly used as water and a low boiling point organic solvent for dissolving the resin, and isopropyl alcohol is used in combination as a low boiling point water-soluble organic solvent functioning as a cosolvent for water and methyl ethyl ketone. As a base, 30 to 1 of the acid groups of the film-forming resin
Preparation of a solution containing water as a main liquid medium containing alcoholamine in an amount sufficient to make the film-forming resin self-water dispersible and glycerin as an anti-drying agent. Then, the chips of the solid coloring compound of (1) are mixed therein, and a pigment suspension is obtained by stirring. More preferably, the suspension is given a high shearing force, and is further dispersed into fine particles using a nanomizer (trademark), which is a dispersing machine capable of obtaining a more sufficient suspension state, without reaggregation. Do.

(3) While stirring the pigment suspension, an aqueous solution containing glycerin as an anti-drying agent is dropped, and the components derived from the pigment and the film-forming resin are substantially equal to or more than 0.01 in average particle diameter. An aqueous dispersion consisting of only colored resin particles (colored microcapsules) of less than 1 μm is obtained.

(4) Methyl ethyl ketone and isopropyl alcohol are distilled off from the obtained aqueous dispersion of colored resin particles to prepare an ink base.

(5) To the ink base, an anionic surfactant consisting of the unsubstituted or substituted naphthalene sulfonate substituted with an alkyl group or an alkoxyl group of the present invention and / or a fluorine-based surfactant are added and heated and reduced in pressure. And concentrate. The amount of the surfactant used is 0. 0 in the ink.
The range is from 01 to 10% by mass, desirably from 0.1 to 5% by mass.

(6) The obtained concentrated base is stirred with water, a water-soluble organic solvent and other chemicals to adjust the concentration and physical properties. Further, filtration is performed to obtain an aqueous ink for inkjet recording. For a water-soluble organic solvent containing a penetrant or an anti-drying agent, it is preferable to use, as one of the penetrants, a 1 to 3 mol adduct of propylene oxide of a lower alcohol having 2 to 4 carbon atoms. The amount is preferably in the range of 0.1 to 10% by mass of the ink. As the anti-drying agent, glycerin and the like are preferable, and the added amount is desirably in the range of 1 to 80% by mass based on the ink.

[0077]

Next, the present invention will be described more specifically with reference to examples and comparative examples. In addition, "part" in the following examples
Represents "parts by mass".

(Example 1) 4.3 parts of quinacridone pigment and styrene-acrylic acid-methacrylic acid resin (styrene / acrylic acid / methacrylic acid = 77/10/13; molecular weight: 50,000; acid value: 160) 3 parts of 8.6 parts of a two-roll kneaded product were mixed with 29.5 parts of water, 2.6 parts of glycerin, 0.9 parts of triethanolamine (48 mol% of resin acid value, equivalent to neutralization ratio), and methyl ethyl ketone. The mixture was stirred in a mixed solution of 9.6 parts and 4.3 parts of isopropyl alcohol, stirred at room temperature for 3 hours, and further subjected to a dispersion treatment at 98 MPa using a disperser Nanomizer (manufactured by Nanomizer) to obtain a pigment suspension. Was.

A mixture of 3.6 parts of glycerin and 40.9 parts of water was added dropwise to 55.5 parts of the obtained suspension at a rate of 5 ml / min while stirring, and magenta colored resin particles were dispersed in water. A liquid was obtained. Methyl ethyl ketone, isopropyl alcohol and part of water were distilled off from the obtained capsule liquid using a rotary evaporator to obtain a final aqueous dispersion of magenta colored resin particles (pigment concentration: 13% by mass).

To 32 parts of this aqueous dispersion, 0.2 parts of alkylnaphthalenesulfonate: compound 3 and 0.2 parts of a fluorine-based surfactant: compound 9 were added, and the mixture was concentrated at 70 ° C. and 30 hPa, and concentrated. (Pigment concentration: 15% by mass) was obtained.

Glycerin 2 was added to 27 parts of the obtained concentrated base.
0 parts, alkyl naphthalene sulfonate: 1.5 parts of compound 3, propylene oxide adduct of propanol:
After adding 5 parts of compound 14 and 46.5 parts of water and stirring,
Filtration was performed using a 0.5 μm filter to obtain an aqueous ink for inkjet recording.

The microcapsules in the obtained aqueous ink have an average particle size of 0.15 μm,
Was 8.0.

This ink showed stable dispersion without aggregation after storage at room temperature for one year, and there was no nozzle clogging. Printing using a thermal inkjet printer (NovaJet Pro) is stable, and the printed matter obtained shows a vivid magenta color without bleeding, and the recording paper immediately after printing is immersed in purified water for 24 hours. The print density did not change at all from the density immediately after printing.

(Example 2) A water-based ink for ink-jet recording was produced by using a mixture of compounds 12 and 13 in place of compound 9 of Example 1.

The microcapsules in the obtained aqueous ink have an average particle size of 0.15 μm,
Was 8.0.

This ink showed stable dispersion without aggregation after storage at room temperature for one year, and there was no nozzle clogging. Printing using a thermal inkjet printer (NovaJet Pro) is stable, and the obtained printed matter has no bleeding, shows a vivid magenta color, and the recording paper immediately after printing is immersed in purified water for 24 hours. The printing density after printing did not change at all from the printing density immediately after printing.

(Comparative Example 1) 20 parts of glycerin and 5 parts of ethanol were added to the final aqueous dispersion of magenta colored resin particles (pigment concentration: 13% by mass) of Example 1, and the pigment conversion of the colored microcapsules in the ink was determined. After adjusting and stirring with water in the same manner as in Example 1, filtration was performed using a 0.5 μm filter to obtain an aqueous ink for inkjet recording.

The microcapsules in the obtained aqueous ink had an average particle size of 0.15 μm and the pH was 8.4. This ink is susceptible to nozzle agglomeration after storage at room temperature for one year with slight aggregation.
Printing using a thermal inkjet printer (NovaJet Pro) was unstable and blurred in a short time.

Examples 1 and 2 are different from the comparative example in comparison with the comparative example.
The dispersion stability was good, there was no nozzle clogging, and the ejection stability of the ink was extremely good. The printing was also clear.

[0090]

The present invention comprises a pigment coated with water, a water-soluble organic solvent, and a film-forming resin having an acid value at least partially neutralized with a base. An anionic surfactant comprising an unsubstituted or substituted alkyl or alkoxyl group-containing naphthalene sulfonate having an acid value of 100 or more and less than 180, containing a base amount equivalent to 30 to 100 mol% thereof, and / or This is a microcapsule-dispersed aqueous jet ink containing a fluorine-based surfactant. The ink of the present invention has a remarkable technical effect that it has excellent dispersion stability, no nozzle clogging, and excellent ink ejection stability.

 ────────────────────────────────────────────────── ─── Continued on front page (72) Inventor Kyoko Nogawa 1-1-7 Kita, Satte-shi, Saitama F-term (reference) 2C056 FC02 2H086 BA52 BA53 BA55 BA59 BA60 4J039 AD03 AD09 BC54 BE01 BE22 CA06 CA11 GA24

Claims (5)

[Claims] 1. A pigment comprising water, a water-soluble organic solvent, and a pigment coated with a film-forming resin having an acid value at least partially neutralized with a base, wherein the acid value of the film-forming resin is 1
Anionic surfactants consisting of unsubstituted or substituted alkyl or alkoxyl naphthalenesulfonates and / or fluorine-based surfactants having a base amount of not less than 00 and less than 180 and equivalent to 30 to 100 mol% A colored microcapsule-dispersed aqueous jet ink comprising an activator. 2. A coating composition comprising water, a water-soluble organic solvent, and a pigment coated with a film-forming resin having an acid value at least partially neutralized with an alcoholamine, wherein the film-forming resin has an acid value of An anionic surfactant and / or a fluorine-based surfactant comprising naphthalene sulfonate which is not less than 100 and less than 180, contains 40 to 60 mol% equivalent of alcoholamine, and is unsubstituted or substituted with an alkyl group or an alkoxyl group. A colored microcapsule-dispersed aqueous jet ink characterized by containing. 3. An anionic surfactant having 2 to 6 carbon atoms.
3. A colored microcapsule-dispersed aqueous jet ink according to claim 1, which is a naphthalene sulfonate substituted with 1 to 2 alkyl groups or alkoxyl groups. 4. The colored microparticle according to claim 1, wherein the fluorinated surfactant is a compound having the following general formula (A) and / or (B). Capsule-dispersed aqueous jet ink. Fluorinated surfactant: General formula (A) m = 1-6, n = 4-12, r = 1-20 Fluorinated surfactant: General formula (B) m = 3-20, n = 4-12 5. The water-soluble organic solvent contains a 1 to 3 mole adduct of propylene oxide of a lower alcohol having 2 to 4 carbon atoms. Item 6. A colored microcapsule-dispersed aqueous jet ink according to Item 4.