JP2001192582A - Coloring particle and ink-jet ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain coloring particles, with a narrow nanometer size distribution, high stability and reproducibility, and to obtain, using such particles, a coloring liquid, easy to disperse into a wide range of solvents from nonpolar to polar, free of dye elution from particles and excellent in coloring, transparency, and dispersion stability. SOLUTION: The liquid is prepared by bringing a dye and an organic compound having ionic groups into reaction with a hydrosol of nanometer-size particles containing a metal oxide and a metal hydroxide, and is stabilized when the particle surface is coated with an organic compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to colored fine particles having good dispersibility and an ink jet ink containing the same.

[0002]

2. Description of the Related Art Dye inks are excellent in terms of transparency, definition and coloring, and are therefore used as inks requiring high definition. However, dye inks have waterfastness and lightfastness issues. In order to solve these problems, inks using organic pigments or carbon black instead of dyes have been manufactured.

[0003] However, in the ink using an organic pigment or carbon black, a method of mechanically pulverizing and dispersing the organic pigment or carbon black with the help of a dispersant is employed. , Very fine, and if not stably dispersed in a medium, not only good transparency, definition and color development cannot be obtained, but also secondary aggregation, problems such as storage stability, and the like. This may cause nozzle clogging.

On the other hand, if the particle size of an organic pigment or carbon black is mechanically reduced to a very small value, the surface energy becomes extremely large, so that not only a large amount of energy is required but also secondary aggregation is prevented. Various measures are required to keep the dispersion stable.

In order to solve such a problem, a method of using colored fine particles in which a dye is microencapsulated is used instead of a conventional method of mechanically pulverizing and dispersing an organic pigment or carbon black with the aid of a dispersant. (JP 6
JP-A-2-95366), a method of using colored emulsion polymerized particles for ink (JP-A-6-313141), W / O
A method of obtaining lake pigment fine particles using an emulsion (Japanese Patent Publication No. 7-47696), a method of adsorbing a dye to porous ceramic fine particles and forming a colorant (Japanese Unexamined Patent Publication No. 9-71)
No. 732) has been studied.

[0006]

However, colored fine particles and colored emulsion polymerized particles in which the dye is microencapsulated have a large particle size, and therefore have problems in transparency, definition, and color development, and furthermore, the concentration of the contained coloring material. , There is a problem that the coloring power is not sufficient.

In the case of lake pigment fine particles prepared using a W / O emulsion, it is difficult to obtain ultrafine particles of several tens of nanometers with good reproducibility because the emulsion is used. Also has the problem of becoming wider. When the particle size distribution of the obtained particles is wide, the saturation is lowered. There is also a problem that the process is complicated.

[0008] When a dye is adsorbed on a porous ceramic fine particle to form a colorant, since a particle aggregate produced by a sol-gel method or the like is used after being pulverized, the colorant having a very small particle size and a narrow particle size distribution is used. It is difficult to get. Further, there is a problem that the process is complicated for adsorbing the dye after preparing the porous ceramic fine particles.

In the case where ink is obtained by dispersing porous particles having adsorbed dye in a liquid medium, the dye is merely physically adsorbed, and therefore, the pH of the liquid medium is changed, or a surfactant is added. Thus, the adsorbed dye may be desorbed again.

Further, when used as an ink, a surfactant may be added, but the surfactant merely physically adsorbs to the porous particles, and the surface active agent is changed due to a change in pH of the liquid medium. The agent may be detached. Desorption of the surfactant impairs its function as an ink.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems. The inventors of the present invention act a dye and an organic compound having an ionic group on a hydrosol of fine particles containing a metal oxide and a metal hydroxide having a particle size of nanometer size,
The present inventors have found that colored fine particles having a narrow particle size distribution of nanometer size, in which the surface of the fine particles is coated with an organic compound, can be obtained stably and with good reproducibility. Further, such colored fine particles can be easily dispersed in a wide range of solvents from non-polar solvents to polar solvents, there is no elution of dye from the particles, and good coloring, transparency, and good dispersion stability are obtained. The inventors have found that a liquid can be obtained, and have completed the present invention.

According to the present invention, colored fine particles having excellent storage stability, transparency, definition, coloring and coloring power can be obtained.
Demonstrates excellent performance as a colorant for inkjet inks.

[0013] The present invention relates to colored fine particles in which the surface of fine particles containing a dye and a metal oxide is coated with an organic compound having an ionic group.

[0014] In a preferred embodiment, the metal oxide is a metal oxide hydrosol.

[0015] In a preferred embodiment, the surface of the fine particles and the ionic group are electrically interacting with each other.

[0016] In another preferred embodiment, the organic compound having an ionic group is an ionic surfactant.

[0017] In a preferred embodiment, the electric interaction is an ionic bond.

[0018] In another preferred embodiment, the surface of the fine particles is coated with an organic compound having the ionic group in a state where the ionic group faces the particle surface,
Further, the periphery thereof is coated with a surfactant having a hydrophobic portion facing inward.

In a preferred embodiment, the CV value representing the particle size distribution of the colored fine particles is 50% or less.

In a more preferred embodiment, the CV value representing the particle size distribution of the colored fine particles is 40% or less.

In a further preferred embodiment, the CV value representing the particle size distribution of the colored fine particles is 30% or less.

In another embodiment, the metal oxide is titanium oxide, aluminum oxide, zirconium oxide,
It is selected from the group consisting of iron oxide, tin oxide, zinc oxide, cerium oxide, and mixtures of two or more thereof.

In another embodiment, the dye is included in the metal oxide, or the dye is adsorbed on the surface of the metal oxide particles.

In still another embodiment, the colored fine particles have an average particle size of 1 nm to 500 nm.

In a more preferred embodiment, the colored fine particles have an average particle size of 3 nm to 250 nm.

In another embodiment, the metal oxide is made from a metal chloride, metal hydroxide, metal nitrate, metal sulfate, or metal acetate.

The present invention also relates to an ink-jet ink containing any of the above-mentioned colored fine particles and a liquid medium.

In a preferred embodiment, the liquid medium is a liquid medium containing water or a hydrophilic organic solvent as a main component.

[0029] In another embodiment, the liquid medium is:
It is a liquid medium mainly composed of a hydrophobic organic solvent.

Further, the present invention provides (a) a step of preparing an aqueous solution of at least one metal compound selected from the group consisting of metal chlorides, metal hydroxides, metal nitrates, metal sulfates, and metal acetates. (B) adjusting the pH of an aqueous solution of the metal compound to form a hydrosol of fine particles containing a metal oxide and a metal hydroxide; (c) an organic compound having an ionic group in the obtained hydrosol To electrically interact the organic compound having an ionic group with the surface of the fine particles, and then transfer the fine particles to an organic solvent layer to form an organosol;
And (d) a step of adding a dye to the organosol to adsorb the dye on the surface of the fine particles, and a method for producing colored fine particles whose surface is coated with an organic compound having an ionic group.

Further, the present invention provides (a) a step of preparing an aqueous solution of at least one metal compound selected from the group consisting of metal chlorides, metal hydroxides, metal nitrates, metal sulfates, and metal acetates. (B) adjusting the pH of the aqueous solution of the metal compound, adding a dye, and preparing fine particles of a hydrosol containing the metal oxide and the metal hydroxide to which the dye has been adsorbed; An organic compound having an ionic group is added to the hydrosol, and the organic compound having an ionic group and the surface of the fine particles are electrically interacted with each other, and then the fine particles are transferred to an organic solvent layer to form an organosol. Process;
And a method for producing colored fine particles whose surface is coated with an organic compound having an ionic group.

The present invention relates to (a) a mixed aqueous solution of a dye and at least one metal compound selected from the group consisting of metal chlorides, metal hydroxides, metal nitrates, metal sulfates, and metal acetates. (B) adjusting the pH of the mixed aqueous solution to prepare a hydrosol of fine particles containing a metal oxide and a metal hydroxide to which a dye is adsorbed; and (c) preparing a hydrosol of the obtained hydrosol. Adding an organic compound having an ionic group to electrically interact the organic compound having an ionic group with the surface of the fine particles, and then transferring the fine particles to an organic solvent layer to form an organosol;
And a method for producing colored fine particles whose surface is coated with an organic compound having an ionic group.

In a preferred embodiment, any one of the above methods further includes a step of treating the obtained colored fine particles with water containing a surfactant or a hydrophilic organic solvent.

The present invention relates to a method for producing an ink-jet ink, wherein in any one of the above-described steps of colored particles, (e) the obtained colored fine particles further comprise water or a hydrophilic organic solvent as a main component. Transferring to a liquid medium or a liquid medium containing a hydrophobic organic solvent as a main component.

[0035]

BEST MODE FOR CARRYING OUT THE INVENTION In the colored fine particles of the present invention, the surfaces of fine particles containing a dye and a metal oxide are coated with an organic compound having an ionic group.

The colored fine particles of the present invention have an average particle diameter of ln.
m to 500 nm, preferably 3 nm to 250 nm
, More preferably in the range of 5 nm to 100 nm. If the average particle size is smaller than 1 nm, problems occur in the colorability and light resistance. If it is larger than 500 nm, problems such as nozzle clogging of the inkjet head are likely to occur when applied to inkjet ink.

Further, the particle size distribution of the colored fine particles of the present invention is expressed by the formula: (standard deviation of average particle diameter / average particle diameter) × 10
The value calculated with 0 (hereinafter referred to as CV value) is preferably 50% or less, more preferably 40% or less, and even more preferably 30% or less. When the CV value is 50% or less, the saturation is further improved.

The size of the colored fine particles can be measured using a laser Doppler type particle size distribution analyzer, a transmission electron microscope, or the like.

The dye used in the present invention is not particularly limited, and any of water-soluble and oil-soluble dyes can be used.

When a water-soluble dye is used, it is preferable to select the dye according to the charge of the fine particles containing a metal oxide and a metal hydroxide. That is, when the fine particles have a positive charge, an acid dye is preferable. When the fine particles have a negative charge, a basic dye is preferred.

The water-soluble dye used in the present invention includes:
Although not particularly limited, for example, C.I. I. Acid Black 2, 7, 24, 26, 31,
52, 63, 112, 118; I. Acid Blue 9, 22, 40, 59, 93,
102, 104, 113, 117, 120, 167, 2
29, 234; I. Acid Red 1, 6, 32, 35, 37, 5
1, 52, 80, 85, 87, 92, 94, 115, 1
80, 256, 317, 315; I. Acid Yellow 11, 17, 23, 25, 2
9, 42, 61, 71; I. Acid Orange 7, 19; I. Basic Black 2; C.I. I. Basic Blue 1, 3, 5, 7, 9, 24,
25, 26, 28, 29; I. Basic Red 1, 2, 9, 12, 13, 1
4, 37; I. Basic Yellow 2, C.I. I. Basic violet 7, 14, 27; I. Food Black 1, 2 and methyl red. These are used alone or in combination of two or more.

As oil-soluble dyes, C.I. I. Solvent Yellow 19, C.I. I. Solvent Red 8, 24, 43, 48, 73 C.I. I. Solvent Blue 2, 11, C.I. I. Solvent Black 3, C.I. I. Solvent Orange 3, 40, 45 C.I. I. Solvent Green 3, 7 C.I. I. Solvent Violet 3 or the like is used.
These are used alone or in combination of two or more.

Other usable dyes include C.I. I. Natural green 3, C.I. I. Natural Red 25, C.I. I. Disperse Yellow 3,5, C.I. I. Disperse Red 4, C.I. I. Disperse Blue 3, C.I. I. Disperse Orange 13 and the like.
These may be used alone or in combination of two or more.

In the present invention, the dye is a metal oxide 10
It is preferably added in an amount of 1 to 80 parts by weight, more preferably 3 to 60 parts by weight, and even more preferably 5 to 50 parts by weight with respect to 0 parts by weight.
If the amount is less than 1 part by weight, sufficient coloring cannot be obtained. If the amount is more than 80 parts by weight, the dye not contained in the fine particles is released.

The metal oxide used in the present invention includes:
Examples include titanium oxide, aluminum oxide, zirconium oxide, iron oxide, tin oxide, zinc oxide, and cerium oxide. Metal oxides can be obtained by mechanical grinding, evaporative condensation,
Nanometer-sized fine particles are obtained by a method appropriately selected and used by those skilled in the art, such as a gas phase reaction method, a precipitation method, and a solvent evaporation method.

As metal oxides, aqueous dispersions of metal oxides and metal oxide hydrosols are also used. The metal oxide hydrosol is prepared, for example, by hydrolyzing an aqueous solution of a metal salt. In addition, the aqueous solution here means
It means a solution using water or a mixture of water and a hydrophilic organic solvent as a solvent.

The metal salts include metal chlorides, metal hydroxides, metal nitrates, metal sulfates, and metal acetates. Specifically, for example, titanium, aluminum,
Zirconium, iron, tin, zinc, or cerium chloride, nitrate, sulfate, or acetate can be used.

When the colored fine particles are prepared by adjusting the pH as described later, the composition becomes a mixture of a metal oxide and a metal hydroxide.

The colored fine particles of the present invention are prepared by incorporating a dye into a metal oxide using a method such as encapsulating the dye in the metal oxide or adsorbing the dye on the surface of the metal oxide particles. And by coating the surface of the fine particles with an organic compound having an ionic group.

First, a metal oxide can be appropriately selected and used by those skilled in the art, for example, a mechanical grinding method,
Metal oxides obtained by evaporating and condensing into fine particles of nanometer size by methods such as vapor condensation method, gas phase reaction method, precipitation method and solvent evaporation method and dispersing them in water to form a dispersion, or hydrolyzing an aqueous metal salt solution Product hydrosol. The colored fine particles of the present invention can be obtained by compounding a dye with the metal oxide dispersion or the metal oxide hydrosol and coating with an organic compound having an ionic group. Coating with an organic compound having an ionic group is achieved by an electrical interaction between the surface of the fine particles and the ionic group. Here, the electrical interaction may be an electrostatic interaction and / or an ionic bond.

For example, a case where the fine particles of the present invention are produced using aluminum chloride which is a metal chloride will be described qualitatively. When pH is adjusted by adding a base to an aluminum chloride aqueous solution, nanometer-order fine particles composed of aluminum oxide and hydroxide are precipitated. Here, for example, when an organic compound having a sulfonic acid group is added to the system, an exchange reaction occurs between the chlorine ion remaining on the surface of the produced particles and the organic compound having a sulfonic acid group. If the exchange reaction product precipitates, the equilibrium shifts in a direction to promote the exchange reaction. As a result, fine particles in which an organic compound having a sulfonic acid group is ion-bonded are obtained as a precipitate.

The colored particles obtained in such a process can be easily redispersed in a liquid medium because the surface of the particles is covered with an organic substance and stabilized, and even in a liquid medium, the particle diameter is on the order of nanometers and narrow. A stable colored liquid is obtained which maintains the particle size distribution and does not elute the dye due to changes in the external environment.

The colored fine particles coated with an organic compound having an ionic group may be further coated with a surfactant. In this case, colored fine particles coated with the surfactant can be obtained with the hydrophobic portion of the surfactant facing inward. By such a treatment, the dispersibility in a liquid medium mainly composed of water can be further improved.

The colored fine particles further coated with a surfactant are also the colored fine particles coated with an organic compound having an ionic group as referred to in the present invention.

The organic compound having an ionic group used in the present invention can be represented by the following formula.

R--X wherein R is a linear, branched or cyclic C6-C2
0 saturated or unsaturated aliphatic hydrocarbon group, C6-C20
Aromatic hydrocarbon group, linear, branched or cyclic C6
An aromatic hydrocarbon group having a saturated or unsaturated hydrocarbon substituent of -C20, a phenol group having a branched or cyclic C6-C20 saturated or unsaturated hydrocarbon substituent,
Examples include a heterocyclic group, a sugar chain, a polyoxyethylene chain, and a polysiloxane chain.

Examples of X include a carboxyl group, a sulfonic acid group, a sulfate group, a phosphoric acid group, and salts thereof, a phosphonium base, an ammonium base, a pyridinium base, an imidazolinium base and the like.

Such organic compounds are not particularly restricted but include, for example, alkyl carboxylate such as sodium laurate, alkyl or alkyl phenol sulfate such as sodium lauryl sulfate, alkyl such as sodium lauryl benzene sulfonate and the like. Alkylbenzene sulfonates, alkyl phosphate esters such as sodium lauryl phosphate, and quaternary salts such as lauryl dimethyl ammonium chloride.
Quaternary ammonium salts and sodium salts of polyoxyethylene succinate monoester.

The coating with an organic compound having an ionic group can be carried out by adding, for example, an organic compound having an ionic group concentration of 5 to 20% to 100 parts by weight of a dispersion of a metal oxide and a metal hydroxide in which a dye is complexed. Is added by 10 to 30 parts by weight to obtain the colored fine particles of the present invention.

Next, the colored fine particles of the present invention are recovered,
For example, with a vacuum dryer or the like, 40 to 100 ° C., for example, 7
Dry at 0 ° C.

Colored fine particles coated with an organic compound having an ionic group in a state where the ionic group is directed toward the particle surface, and further coated with a surfactant having a hydrophobic portion directed inward around the organic compound. Is obtained by treating colored fine particles coated with the organic compound having an ionic group with water or a hydrophilic organic solvent to which a surfactant is added. The colored fine particles thus obtained are preferably used for aqueous or hydrophilic ink.

The surfactant to be added is not particularly limited, and ionic surfactants, nonionic surfactants and the like are used. As the ionic surfactant, for example,
Alkyl carboxylate such as sodium laurate, alkyl or alkyl phenol sulfate such as sodium lauryl sulfate, alkyl or alkyl benzene sulfonate such as sodium dodecyl sulfonate, sodium dodecyl benzene sulfonate, alkyl such as sodium lauryl phosphate Phosphate ester salt, lauryl dimethyl ammonium chloride,
Quaternary ammonium salts such as hexadecyltrimethylammonium chloride, alkylbetaines such as betaine lauryldimethylacetate and 2-undecyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, and other alkylpyridinium salts and alkylamino acid salts And the like.

Examples of the nonionic surfactant include, for example,
Glycerin monostearate, sorbitan stearate, sucrose stearate, polyoxyethylene oleyl ether, polyoxyethylene nonylphenyl ether, dodecyl polyoxyethylene ether and the like can be mentioned.

In the coating with a surfactant, the colored fine particles, the surface of which is coated with an organic compound having an ionic group,
For example, it is carried out by treating with water or a hydrophilic organic solvent containing a surfactant at a concentration of 5 to 20%.

Hereinafter, a method for producing colored fine particles whose surface is coated with an organic compound having an ionic group will be described.
First, the first method includes the following steps: (a) at least one metal selected from the group consisting of metal chlorides, metal hydroxides, metal nitrates, metal sulfates, and metal acetates (B) adjusting the pH of the aqueous solution of the metal compound to prepare a hydrosol of fine particles containing a metal oxide and a metal hydroxide; Adding an organic compound having an ionic group to electrically interact the organic compound having an ionic group with the surface of the fine particles, and then transferring the fine particles to an organic solvent layer to form an organosol;
And (d) a step of adding a dye to the organosol to adsorb the dye on the surface of the fine particles.

The second method comprises the following steps: (a) at least one selected from the group consisting of metal chlorides, metal hydroxides, metal nitrates, metal sulfates, and metal acetates. (B) adjusting the pH of the aqueous solution of the metal compound, adding a dye, and forming fine particles of a hydrosol containing the metal oxide and the metal hydroxide to which the dye is adsorbed; And (c) adding an organic compound having an ionic group to the obtained hydrosol so that the organic compound having an ionic group and the surface of the fine particles are electrically interacted with each other. Step of transferring to a layer to form an organosol.

The third method comprises the following steps: (a) at least one selected from the group consisting of metal chlorides, metal hydroxides, metal nitrates, metal sulfates, and metal acetates. Preparing a mixed aqueous solution of a metal compound and a dye; (b) adjusting the pH of the mixed aqueous solution to prepare a hydrosol of fine particles containing a metal oxide and a metal hydroxide to which the dye has been adsorbed; and (C) adding an organic compound having an ionic group to the obtained hydrosol, thereby electrically interacting the organic compound having an ionic group with the surface of the fine particles; and then transferring the fine particles to the organic solvent layer. And making it into an organosol.

Further, it is coated with an organic compound having an ionic group in a state where the ionic group is directed to the particle surface side, and the periphery thereof is further coated with a surfactant having a hydrophobic portion directed inward. The colored fine particles can be obtained by further treating the colored fine particles obtained by any of the above methods with water or a hydrophilic organic solvent containing a surfactant.

Whether the obtained colored fine particles are coated with the organic compound having an ionic group can be determined as follows. For example, after dispersing the obtained colored fine particles in an amphipathic solvent such as alcohol, the particles are collected by centrifugation or the like, and the organic components in the remaining liquid are analyzed using an analysis means such as gas chromatography or liquid chromatography. .
If this organic compound has an ionic bond, almost no organic compound having an ionic group is found in the solvent.However, when the organic compound having an ionic group is present on the particle surface by mere physical adsorption, it is eluted into the solvent. So you can clearly check.

Further, there are a method of measuring zeta potential and a method of measuring by solid-state NMR.

The ink-jet ink of the present invention comprises colored fine particles and a liquid medium, and is obtained by dispersing colored fine particles in a liquid medium.

In the ink-jet ink of the present invention, the colored fine particles are preferably contained in an amount of about 0.5 to 80% by weight, more preferably about 2 to 60% by weight based on the total weight of the ink.

The liquid medium used in the ink-jet ink of the present invention is preferably a mixed solvent of water and a hydrophilic organic solvent. As the water, it is preferable to use deionized water instead of general water containing various ions.

Examples of the hydrophilic organic solvent used by mixing with water include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol,
C1-C4 alkyl alcohols such as ert-butyl alcohol and isobutyl alcohol; amides such as dimethylformamide and dimethylacetamide; ketone or keto alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane Polyalkylene glycols such as polyethylene glycol and polypropylene glycol; ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol;
Alkylene glycols in which the alkylene group contains 2 to 6 carbon atoms, such as diethylene glycol; glycerin;
Ethylene glycol methyl (or ethyl) ether,
Lower alkyl ethers of polyhydric alcohols such as diethylene glycol methyl (or ethyl) ether and triethylene glycol monomethyl (or ethyl) ether; N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidine and the like. Can be.

Particularly preferred are those containing a polyhydric alcohol having an effect of preventing ink from drying as a hydrophilic organic solvent. Of these, polyhydric alcohols such as diethylene glycol and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether are preferred.

The content of the hydrophilic organic solvent in the ink-jet ink of the present invention is preferably 9 to 80% by weight, more preferably 20 to 50% by weight based on the total weight of the ink.

The content of water is determined in a wide range depending on the kind and composition of the above-mentioned hydrophilic organic solvent or required physical properties of the ink, but is preferably about 10 to 90% by weight of the total weight of the ink. 10-70% by weight is more preferred, and about 20-70% by weight is even more preferred.

The ink-jet ink of the present invention may contain a dispersant, a surfactant, a viscosity adjuster, a surface tension adjuster, and the like, which are used by those skilled in the art as needed, in addition to the above components.

In the ink-jet ink of the present invention, as described above, the colored fine particles obtained by each of the above methods may be once isolated and then dispersed in a target solvent. Instead, an ink-jet ink can be directly produced. For example, after the last step of the first, second, or third colored fine particle production step, a liquid medium (water or a hydrophilic organic solvent mainly composed of water or a hydrophilic organic solvent) used for an inkjet ink is used. (A liquid medium containing as a main component) the inkjet ink of the present invention.

Further, it is coated with an organic compound having an ionic group in a state where the ionic group is directed to the particle surface side,
Furthermore, the inkjet ink containing the colored fine particles, the periphery of which is coated with a surfactant having a hydrophobic portion facing inward, can be used without further isolation of the colored fine particles obtained by any of the methods described above. After treatment with water or a hydrophilic organic solvent containing an activator, a liquid medium (a liquid medium containing water or a hydrophilic organic solvent as a main component or a liquid medium containing a hydrophobic organic solvent as a main component) used for inkjet ink is added. It is obtained by shifting.

The substrate on which the ink-jet ink of the present invention is used includes general paper, coated paper, synthetic paper, various plastic films and the like, and is not particularly limited.

[0082]

Hereinafter, the present invention will be described with reference to examples.
The present invention is not limited to the embodiments.

Example 1 Preparation of Colored Fine Particles 5% -T
LiCl ₄ solution 100ml of 10% _-Na 2 CO ₃ solution about 12ml was added to the pH of the solution was prepared titanium oxide hydrosol by controlling the 1.2-1.3.
Approximately 30 ml of a 2% aqueous solution of sodium dodecylbenzenesulfonate (SDS) was added to the aqueous titanium oxide hydrosol dispersion to prepare a titanium oxide organosol in which a surfactant was densely adsorbed on the surface of the hydrosol. Then _TiO 2-SDS organosol separated from the aqueous phase was collected and dried at 70 ° C. in a vacuum dryer _TiO 2-SDS
Particles were obtained.

To 10 ml of a 10% toluene dispersion of the TiO ₂ -SDS particles was added methyl red (MR) as a dye.
50 mg was added, and MR was adsorbed on the TiO ₂ -SDS surface. After standing for 30 minutes, methanol was added to the toluene dispersion to reprecipitate the TiO ₂ -SDS / MR adsorbent, thereby obtaining colored fine particles of the present invention.

The particles of the present invention were easily dispersed in a wide range of solvents from non-polar solvents such as toluene, ethylene glycol diethyl ether and tetrahydrofuran to highly polar solvents. The toluene dispersion was transparent, and there was no precipitation or turbidity even after standing for one month. When the particle size distribution in the toluene dispersion was measured with a laser Doppler type particle size distribution meter, the average particle size was 74.1 nm, and the CV value was 12.28%.
Met.

Example 2 Preparation of Colored Fine Particles 5% -T
LiCl ₄ solution 100ml of 10% _-Na 2 CO ₃ solution about 12ml addition, by controlling the pH of the solution to 1.2 to 1.3 to prepare a titanium oxide hydrosol. In addition, C.I. I. Basic Blue 26 50mg
In addition, after adsorbing to an oxide hydrosol, about 30 ml of a 2% aqueous solution of sodium dodecylbenzenesulfonate (SDS) was added to prepare a TiO ₂ -SDS organosol / dye adsorbent. The TiO ₂ -SDS organosol / dye adsorbent separated from the aqueous phase is collected and placed in a vacuum dryer at 70 ° C.
To obtain colored fine particles of the present invention.

The particles of the present invention were easily dispersed in a wide range of solvents from non-polar solvents such as toluene, ethylene glycol diethyl ether and tetrahydrofuran to highly polar solvents. The toluene dispersion was transparent, and there was no precipitation or turbidity even after standing for one month. When the particle size distribution in the toluene dispersion was measured by a laser Doppler type particle size distribution analyzer, the average particle size was 10.2 nm, and the CV value was 12.08%.
Met. The content of the dye was 4% by weight.

Example 3 Preparation of Colored Fine Particles 10% A
lCl ₃ · 6H ₂ O aqueous solution 100ml to 10% -Na ₂
About 4 ml of a CO ₃ aqueous solution was added, and the pH of the solution was adjusted to 3.0 to 3.0.
An alumina hydrosol was prepared by controlling to 4.0. In addition, C.I. I. Basic Red 1 50m
g, and adsorbed on the oxide hydrosol, and about 30 ml of a 2% aqueous solution of sodium dodecylbenzenesulfonate (SDS) was added to prepare an Al ₂ O ₃ -SDS organosol / dye adsorbent. Al ₂ O ₃ —S separated from the aqueous phase
The DS organosol / dye adsorbent was recovered and dried at 70 ° C. in a vacuum dryer to obtain the colored fine particles of the present invention.

The particles of the present invention were easily dispersed in a wide range of solvents from non-polar solvents such as toluene, ethylene glycol diethyl ether and tetrahydrofuran to highly polar solvents. The toluene dispersion was transparent, and there was no precipitation or turbidity even after standing for one month. When the particle size distribution in the toluene dispersion was measured by a laser Doppler type particle size distribution analyzer, the average particle size was 12.5 nm and the CV value was 47.59%.
Met. The content of the dye was 6% by weight.

Example 4 Preparation of Colored Fine Particles 2% -A
l (OH) ₃ /10% KOH solution in 100 ml 1N-
About 80 ml of an aqueous HCl solution was added to adjust the pH of the solution to 8.0 to 8.0.
An alumina hydrosol was prepared by controlling to 9.0. In addition, C.I. I. Acid Blue 40 50m
g added after adsorption to an oxide hydrosol, 2% - was prepared adding _Al 2 _O 3 -HTAC organosol / dye adsorbent hexadecyl trimethyl ammonium (HTAC) aqueous solution of about 100ml to chloride. Al ₂ separated from aqueous phase
The O ₃ -HTAC organosol / dye adsorbent was recovered and dried in a vacuum dryer at 70 ° C. to obtain colored fine particles of the present invention.

The particles of the present invention were easily dispersed in a wide range of solvents from non-polar solvents such as toluene, ethylene glycol diethyl ether and tetrahydrofuran to highly polar solvents. The toluene dispersion was transparent, and there was no precipitation or turbidity even after standing for one month. When the particle size distribution in the toluene dispersion was measured by a laser Doppler type particle size distribution analyzer, the average particle size was 8.3 nm, and the CV value was 46.41%. The content of the dye was 7% by weight.

This toluene dispersion of colored particles was used as the ink of the present invention. This ink was filled in the ink tank of a modified inkjet printer (PM-750C manufactured by Seiko Epson Corporation) and an ejection test was performed. As a result, it was found that this ink was ejected normally and could be used as an ink for an inkjet printer. did. The print density is
The density was comparable to the original ink of the printer. It was also found that this ink had little bleeding on paper and was excellent in water resistance.

(Example 5: Preparation of aqueous ink for ink jet recording) 0.75 g of the colored fine particles prepared in Example 2
To tetraethylene glycol monobutyl ether 2.0
g of glycerin.
5 g and a mixed solution of 2.2 g of diethylene glycol were added to obtain an inkjet ink of the present invention.

When the particle size distribution in the ink was measured by a laser Doppler type particle size distribution meter, the average particle size was 25 nm.
Met.

When this ink was filled into an ink tank of an ink jet printer (PM-750C manufactured by Seiko Epson Corporation) and a discharge test was carried out, it was found that this ink was discharged normally and could be used as an ink for an ink jet printer. found. The print density was a density comparable to the original ink of the printer. Also,
It was also found that this ink had little bleeding on paper and was excellent in water resistance.

Example 6: Aqueous ink for inkjet recording
Preparation of ink) 5% -TiCl₄10 in 100 ml of aqueous solution
% -Na₂CO₃Add about 12 ml of aqueous solution and adjust the pH of the solution.
Is controlled to 1.2 to 1.3 to obtain titanium oxide
Idrosol was prepared. In addition, C.I. I. Basic
50 mg of Roux-26 was added and absorbed in the oxide hydrosol.
And then add about 30 ml of 2% SDS aqueous solution₂−
An SDS organosol / dye adsorbent was prepared. This water soluble
TiO from liquid₂-Extract SDS organosol / dye adsorbent
And then washed with water and concentrated to TiO 2 ₂-SD
A toluene solution of the S organosol / dye adsorbent was obtained.

This was added to 10 ml of a 0.5% SDS aqueous solution and subjected to a dispersion treatment using an ultrasonic homogenizer. The dispersion was stirred overnight at room temperature to obtain a highly transparent colored liquid. This was added to a mixed solution of 10 g of deionized water, 2.5 g of glycerin, and 2.2 g of diethylene glycol to obtain an inkjet ink of the present invention. When the particle size distribution in the ink was measured with a laser Doppler type particle size distribution meter, the average particle size was 71 nm. An ink ejection test was performed in the same manner as in Example 5. The print density was a density comparable to the original ink of the printer. In addition, the ink did not bleed on paper, and was excellent in water resistance.

(Examples 7 to 9: Preparation of Colored Fine Particles and Inkjet Ink) The amount of Na ₂ CO ₃ aqueous solution added to the AlCl ₃ .6H ₂ O aqueous solution was changed to adjust the pH of the solution to 2.5, Three types (pH) were controlled in the same manner as in Example 3, except that the timing of addition of the dye and the aqueous solution of SDS was adjusted for each Example.
The colored fine particles of Examples 7, 8 and 9) were prepared in the order of decreasing order.

Using the obtained colored fine particles of Examples 7 to 9 and Example 3, aqueous inks for ink jet recording were produced. 0.75 g of each colored fine particle was dispersed in 2.0 g of tetraethylene glycol monobutyl ether, which is a nonionic surfactant, and this was added to a mixed solution of 15 g of deionized water, 2.5 g of glycerin, and 2.2 g of diethylene glycol, and the dispersion was added. An ink for inkjet of the invention was obtained.

When the particle size distribution in the ink was measured by a laser Doppler type particle size distribution meter, the average particle size of the colored fine particles of Example 3 was 14.4 nm, and the CV value was 49.59%. The average particle diameter of the colored fine particles of Example 7 was 18.3.
At 4 nm, the CV value was 56.39%. The average particle diameter of the colored fine particles of Example 8 is 14.2 nm, and the CV value is 34.
It was 54%. The average particle diameter of the colored fine particles of Example 9 was 13.2 nm, and the CV value was 21.17%.

An ink-jet printer (PM-750C manufactured by Seiko Epson Corporation) was used for the obtained ink of each example.
And the ejection test was performed. This ink was ejected normally and proved to be usable as an ink for an ink jet printer. The print density is
The density was comparable to the original ink of the printer. Further, it was also found that the present ink has little bleeding on paper and is excellent in water resistance.

Further, using the samples printed on the recording paper and the OHP sheet using these inks, the saturation was visually evaluated. As a result, it was found that all the print samples of each ink had practically sufficient saturation. Among them, the chroma of the print sample using the colored fine particles of Example 9 was the highest. The print sample using the colored fine particles of Example 8 had the second highest saturation. The saturation of Example 3 and Example 7 was the same level on the recording paper, but the saturation of Example 3 was high on the OHP sheet. Such a difference in saturation is determined by the particle size distribution (CV value).
It is thought to be due to

Further, when the sample printed on the OHP sheet was projected with a projector and evaluated, the samples of Examples 9, 8 and 3 were particularly high in density and clear.

[0104]

Industrial Applicability According to the present invention, it is possible to easily disperse in a non-polar solvent and a polar solvent, and to prepare a nano-sized dispersion capable of preparing a dispersion having excellent storage stability, transparency, coloring properties and coloring power. Is obtained, and exhibits excellent performance as a coloring material of an inkjet ink.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 11/00 B41J 3/04 101Y

Claims (22)

[Claims] 1. Colored fine particles in which the surface of fine particles containing a dye and a metal oxide is coated with an organic compound having an ionic group. 2. The colored fine particles according to claim 1, wherein the metal oxide is a metal oxide hydrosol. 3. The colored particle according to claim 1, wherein the surface of the fine particle and the ionic group interact electrically. 4. The colored fine particles according to claim 1, wherein the organic compound having an ionic group is an ionic surfactant. 5. The colored fine particles according to claim 1, wherein the electric interaction is an ionic bond. 6. An interface in which the surface of the fine particles is coated with an organic compound having the ionic group in a state where the ionic group is directed to the particle surface side, and furthermore, an interface around which the hydrophobic portion is directed inward. The colored fine particles according to any one of claims 1 to 5, which are coated with an activator. 7. The colored fine particles according to claim 1, wherein a CV value representing a particle size distribution of the colored fine particles is 50% or less. 8. The colored fine particles according to claim 1, wherein a CV value representing a particle size distribution of the colored fine particles is 40% or less. 9. The colored fine particles according to claim 1, wherein a CV value representing a particle size distribution of the colored fine particles is 30% or less. 10. The method of claim 1, wherein the metal oxide is selected from the group consisting of titanium oxide, aluminum oxide, zirconium oxide, iron oxide, tin oxide, zinc oxide, cerium oxide, and mixtures of two or more thereof. 1 to 9
The colored fine particles according to any one of the above items. 11. The colored fine particles according to claim 1, wherein the dye is included in the metal oxide, or the dye is adsorbed on the surface of the metal oxide particle. 12. The colored fine particles have an average particle size of 1 nm.
The colored fine particles according to any one of claims 1 to 11, which have a thickness of from 500 to 500 nm. 13. The colored fine particles having an average particle size of 3 nm.
The colored fine particles according to any one of claims 1 to 11, wherein the colored fine particles have a thickness of from 250 nm to 250 nm. 14. The colored fine particles according to claim 1, wherein the metal oxide is produced from a metal chloride, a metal hydroxide, a metal nitrate, a metal sulfate, or a metal acetate. . 15. An ink-jet ink containing the colored fine particles according to claim 1 and a liquid medium. 16. The ink-jet ink according to claim 15, wherein the liquid medium is a liquid medium containing water or a hydrophilic organic solvent as a main component. 17. The ink-jet ink according to claim 15, wherein the liquid medium is a liquid medium containing a hydrophobic organic solvent as a main component. (A) preparing an aqueous solution of at least one metal compound selected from the group consisting of metal chlorides, metal hydroxides, metal nitrates, metal sulfates, and metal acetates; (b) Adjusting the pH of the aqueous solution of the metal compound to form a hydrosol of fine particles containing a metal oxide and a metal hydroxide; and (c) adding an organic compound having an ionic group to the obtained hydrosol. Electrically interacting an organic compound having an ionic group with the surface of the fine particles, and then transferring the fine particles to an organic solvent layer to form an organosol;
And (d) a step of adding a dye to the organosol to adsorb the dye on the surface of the fine particles, the method comprising the steps of: 19. (a) preparing an aqueous solution of at least one metal compound selected from the group consisting of metal chlorides, metal hydroxides, metal nitrates, metal sulfates, and metal acetates; Adjusting the pH of the aqueous solution of the metal compound, adding a dye, and preparing fine particles of a hydrosol containing a metal oxide and a metal hydroxide to which the dye is adsorbed; and (c) adding ions to the obtained hydrosol. Adding an organic compound having an ionic group to electrically interact the organic compound having an ionic group and the surface of the fine particles, and then transferring the fine particles to an organic solvent layer to form an organosol;
A method for producing colored fine particles, the surface of which is coated with an organic compound having an ionic group. 20. (a) A step of preparing a mixed aqueous solution of at least one metal compound selected from the group consisting of metal chlorides, metal hydroxides, metal nitrates, metal sulfates, and metal acetates, and a dye. (B) adjusting the pH of the mixed aqueous solution to prepare a fine particle hydrosol containing a metal oxide and a metal hydroxide to which a dye has been adsorbed; and (c) adding an ionic group to the obtained hydrosol. Adding an organic compound having the ionic group to electrically interact the organic compound having an ionic group with the surface of the fine particles, and then transferring the fine particles to an organic solvent layer to form an organosol;
A method for producing colored fine particles, the surface of which is coated with an organic compound having an ionic group. 21. The method for producing colored fine particles according to claim 18, further comprising a step of treating the obtained colored fine particles with water containing a surfactant or a hydrophilic organic solvent. 22. A method for producing an ink-jet ink, wherein each of the steps described in any one of claims 18 to 21 further comprises (e) adding the obtained colored fine particles to water or a hydrophilic organic solvent. Transferring to a liquid medium containing a main component or a liquid medium containing a hydrophobic organic solvent as a main component;
A method for producing an ink jet ink.