JPH1046078A - Production of pigment ink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a pigment ink composed of a uniformly micronized pigment. SOLUTION: A micronization treatment of a pigment to a water dispersion is performed after a dye adsorption process to an interlayer compound by using a flowing tube type 3 or an annular type sand mill. Preferably, a precrushing treatment of the interlayer compound to the water dispersion is performed to obtain an average particles diameter of the interlayer compound of <=0.5μm before the dye adsorption process by using the same crushing apparatus. Further, in the precrushing treatment and the micronization treatment, specific gravity of the crushing media and average particle diameter are preferably optimized. By such treatments, final average particle diameter of the pigment is made to be <=0.3μm in the case where the interlayer compound is smectite and final average particle diameter of the pigment is made to be <=25μm in the case where the interlayer compound is hydrotalcite.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a pigment ink which can be used for image formation by a so-called ink jet recording system.

[0002]

2. Description of the Related Art In recent years, with the spread of personal computers and the like, it has been required to display image information and the like created by the personal computers on recording paper in the same manner as silver halide photographs. As a means for printing on recording paper, an ink jet recording method or the like is used in which a solution ink is ejected from a nozzle onto the recording paper by using a driving source such as an electric field, heat, pressure, or the like, and an image is formed with the ink to perform printing. ing.

In the above-mentioned ink jet recording system,
Generally, an aqueous ink is used as the ink, and a recording paper having a dye receiving layer formed on a support is used as the recording paper.

[0004] The coloring material of the water-based ink is suitable for printing and photographing by office automation equipment used indoors from the viewpoint of the convenience that the device is not easily clogged and the maintenance of the device is easy, or Due to the high quality of the image, water-soluble dyes are generally used. On the other hand, pigments excellent in image durability are generally used for posterior or signboards used outdoors or for industrial applications such as printing on cardboard paper. Hereinafter, an aqueous ink using a dye as a coloring material is referred to as a dye ink, and an aqueous ink using a pigment as a coloring material is referred to as a pigment ink.

As pigments used in pigment inks, organic pigments having a specific molecular structure represented by phthalocyanines and quinacridones tend to be used rather than inorganic pigments having a problem in safety.

[0006]

However, such organic pigments are expensive, and because of their limited types, there is a limit in the synthesis technology to reproduce full color. It is difficult to get. Furthermore, depending on the particle size, if the aggregate of the molecules constituting the pigment itself has a relatively high refractive index, light scattering on the pulp when printed on plain paper increases, resulting in multiple internal reflections. Is likely to be affected by the image, and the saturation of the image is expected to decrease. In addition, general organic molecules tend to lower their molecular extinction coefficient due to association, and therefore, the coloring power of an organic pigment is lower than that of a dye at the same addition amount. When the coloring power and the saturation decrease, the sharpness of the image deteriorates.

[0007] In order to put pigment ink into practical use,
In order to prevent clogging at the nozzle tip portion whose opening is becoming narrower with higher definition, it is also required to use a pigment having a small particle size and to ensure excellent dispersion stability over a long period of time.

[0008] For this reason, there has been proposed a manufacturing apparatus for reducing the particle size of a pigment to a colloid level as disclosed in US Pat. No. 4,533,254, and US Pat.
There has been proposed a resin-based dispersant for improving dispersion stability, as disclosed in US Pat.

However, even if these techniques are applied, the problems of cost and toning cannot be solved.

Therefore, the present applicant has proposed to use the intercalation compound as a pigment, taking advantage of the fact that the intercalation compound can fix and hold the dye by an intercalation reaction based on an ion exchange action. As a result, it is possible to obtain a pigment ink that can produce a color tone comparable to that of the dye ink, can be manufactured by a simple process, and can reduce the cost.

However, in order to make such a pigment ink usable for image formation by an ink jet recording method, the pigment must be removed so as not to induce clogging at the nozzle tip or to make the ejection property unstable. It is necessary to uniformly reduce the size.

Accordingly, it is an object of the present invention to provide a method for producing a pigment ink comprising a pigment which is uniformly finely divided.

[0013]

The method for producing a pigment ink according to the present invention achieves the above-mentioned object, and at least a part of interlayer ions in an interlayer compound has a polarity opposite to that of the interlayer ions. It has a dye adsorption step of substituting with a specific dye ion to obtain a pigment, and a fine pulverization step of performing a fine pulverization treatment on an aqueous dispersion of the pigment using a flow tube type or annular type sand mill as a pulverizing device. is there.

In order to obtain a sufficiently finely divided pigment,
It is necessary to use a pulverizer having a large shearing force and excellent pulverizing ability. Conventionally, as a grinding method,
A method of dry pulverization using a pulverizer such as a hammer mill, a ball mill, a jet stream mill, a tube mill, and a tower mill, and a method of wet pulverization using a ball mill, an attritor, a homogenizer, and the like are known. However, even if the pulverization is performed for a long time, a finely divided pigment that can be used for image formation by an ink jet method cannot be obtained. Therefore, in the present invention,
Wet pulverization is performed using a flow tube type or annular type sand mill as a pulverization apparatus. As a result, the pigment can be sufficiently refined in a short time, so that when the pigment ink thus obtained is used for image recording of an ink jet system, clogging of the nozzle can be prevented, and the ejection property is also improved. Stabilize.

The above-mentioned pulverizing treatment is preferably performed not only after the dye adsorption step but also before the dye adsorption step.
That is, before the dye adsorption step, a pre-pulverization step of performing a pre-pulverization treatment on an aqueous dispersion of an intercalation compound using a flow tube type or annular type sand mill as a pulverizer is provided. Then, the average particle size of the intercalation compound is set to 0.1.
The thickness is preferably 5 μm or less.

When the preliminary pulverization is not performed, or when the preliminary pulverization is insufficient and the average particle size of the intercalation compound is larger than 0.5 μm, the surface of the large massive intercalation compound is treated with an organic substance in the dye adsorption step. Since a certain paint is coated, not only the amount of the dye introduced into the interlayer compound becomes insufficient, but also in the subsequent pulverization step, sufficient pulverization cannot be performed. On the other hand, in the preliminary pulverization step, when the dye adsorbing step is performed after sufficiently pulverizing the intercalation compound, the dye can be efficiently introduced into the intercalation compound, so that a pigment having excellent coloring properties can be obtained. Also,
In the subsequent pulverization step, efficient pulverization can be performed, so that the average particle size of the pigment finally obtained can be sufficiently reduced.

The above-mentioned flow tube type or annular type sand mill is such that a grinding medium is filled in the inside thereof and grinding is performed by the shearing force of the grinding medium. Here, the specific gravity is 3.5 to
8.0, using a pulverizing medium having an average particle diameter of 0.8 to 1.6 mm, and a pulverizing medium having a specific gravity of 3.5 to 8.0 and an average particle diameter of 0.2 to 0.8 mm for the fine pulverization treatment. It is preferable to use media.

If the specific gravity of the grinding media is less than 3.5, the movement of the grinding media and the intercalation compound (or pigment) is assimilated, and the interlayer compound (or pigment) cannot be sufficiently sheared. On the other hand, when the specific gravity is larger than 8.0, the crushing media becomes difficult to move, so that the movement of the stirring blade is not transmitted to the crushing media,
On the contrary, a sufficient shearing action cannot be given to the interlayer compound (or pigment). Also, in the preliminary grinding treatment, if the average particle size of the grinding media is less than 0.8 mm, the kinetic energy per grinding media is insufficient, so that coarse aggregates cannot be broken, and conversely,
If it is larger than 1.6 mm, the efficiency of trapping between the pulverized media decreases, so that a sufficient shearing action cannot be given to the entire intercalation compound (or pigment). on the other hand,
In the fine pulverization treatment, the average particle size of the pulverization media is set to 0.1.
If it is less than 2 mm, the movement of the pulverized media and the intercalation compound (or pigment) is assimilated, so that the intercalation compound (or pigment) cannot be given a sufficient shearing action. It becomes difficult. Conversely, if the average particle size of the pulverized media is larger than 0.8 mm, the efficiency of trapping between the pulverized media decreases, so that a sufficient shearing action cannot be given to the entire intercalation compound (or pigment), and The average particle size cannot be reduced to a desired size.

In the case where a montmorillonite group mineral having a smectite structure is used as an interlayer compound and a pigment is obtained using at least one of a basic direct dye and a cationic dye as a dye ion, the pigment is pulverized to obtain an average pigment. The particle size is preferably set to 0.30 μm or less. However, when the montmorillonite group mineral is used as the intercalation compound in this way, since the viscosity in water is remarkably increased, it may be difficult to perform a preliminary pulverization treatment before the dye adsorption step.

When a pigment is obtained using a hydrotalcite group mineral as an interlayer compound and at least one of a direct dye and an acid dye as a dye ion, the average particle size of the pigment is reduced to 0 by fine pulverization. .25 μm or less. When the hydrotalcite group mineral is used as the interlayer compound as described above, it is preferable to perform the preliminary pulverization before the dye adsorption step as described above.

In the present invention, since the pigment is wet-pulverized, an aqueous dispersion of the finely divided pigment is obtained after the completion of the pulverization step. Therefore, it can be used as it is as a pigment ink, but in practice,
A pigment ink is obtained by filtering with a filter, adjusting the pigment concentration, and adding a desired additive.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described.

First, the characteristics of the pigment contained in the pigment ink manufactured according to the present invention will be described.
In this pigment, at least a part of interlayer ions in the interlayer compound is replaced with a specific dye ion having a polarity opposite to that of the interlayer ions. That is, a pigment is used as the pigment by utilizing the fact that the intercalation compound can fix and hold the dye by an intercalation reaction based on an ion exchange action.

Here, the interlayer compound has a layered structure,
Any layered inorganic polymer having exchangeable ions capable of ion exchange with the water-soluble dye between the hydrophilic layers may be used.

The exchangeable ions of the layered inorganic polymer include:
When the water-soluble dye is a water-soluble cationic dye, it is an exchangeable cation such as sodium ion, and when the water-soluble dye is a water-soluble anion dye, it is an exchangeable anion such as carboxyl anion.

Examples of the layered inorganic polymer having exchangeable cations (hereinafter, referred to as cation exchangeable intercalation compound) include natural or synthetic layered silicates or their calcined products. A montmorillonite group mineral having a 3-octahedral smectite structure can be preferably used. This montmorillonite group mineral can be represented by the following chemical formula 1.

[0027]

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Specifically, montmorillonite, magnesia montmorillonite, iron montmorillonite, iron magnesia montmorillonite, beidellite, aluminian beidellite, nontronite, aluminian nontronite, Examples thereof include natural products and synthetic products such as saponite, aluminian saponite, hectorite, and sauconite. It should be noted that those obtained by substituting the OH group in the above formula 1 with fluorine can also be used.

In addition to the montmorillonite group minerals shown in Chemical formula 1, mica group minerals such as sodium silicic mica, sodium teniolite and lithium teniolite can also be used as the cation exchangeable intercalation compound. Further, as in the case of the synthetic clay mineral, examples of the cation-exchangeable interlayer compound having a layered structure and having exchangeable cations include acidic salts such as zirconium phosphate and layered hydrous titanium oxide. These have optical opacity or a unique color, and can be used when transparency, gloss, and whiteness are not simultaneously required.

As synthetic silicates having a strong affinity for cationic dyes, there are amorphous synthetic silicas and the like, which have a dye fixing ability in a high dielectric constant medium such as water, that is, an ion exchange ability of montmorillonite. Not enough compared to group minerals. However, it can be used when high ion exchange capacity is not required.

When a fine powder having a pure white color such as a synthetic silicate containing no impurities is used as the above-mentioned cation exchangeable intercalation compound, the fine powder crystal itself is optically transparent. It is possible to form a pigment that achieves high saturation comparable to salt-based photography.

The exchangeable cations present between the layers of the cation-exchangeable interlayer compound as described above are organic compounds that have the effect of increasing the interlayer distance (pillar effect) and the effect of partially hydrophobizing the layers. It may be substituted by a cation. Examples of such an organic cation include a quaternary ammonium ion, a phosphonium ion, an alkylphosphonium ion, and an arylphosphonium ion. When substituting with a quaternary ammonium ion, at least three of the four alkyl groups each have 4 or more carbon atoms,
It is preferably 8 or more, which is suitable. When the number of long-chain alkyls is small, the pillar effect is not sufficient, and it is difficult to secure an interlayer as a fixing seat (exchangeable inorganic cation).

On the other hand, the layered inorganic polymer having exchangeable anions (hereinafter referred to as anion-exchangeable intercalation compound) is a kind of 0: 1 type clay mineral and is a layered inorganic material composed of AlO ₆ octahedral sheet. Hydrotalcite group minerals can be preferably exemplified. A typical example of such hydrotalcite group minerals is a natural hydrotalcite as shown in Chemical formula 2.

[0034]

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In the present invention, in particular, Mg _0.7 Al
It is preferable to use a fired body of hydrotalcite represented by a composition formula of _0.3 O _1.16 .

Although the composition is slightly different from the composition of natural hydrotalcite shown in Chemical formula 2, synthetic hydrotalcite is also commercially available. Although the fine powder of this synthetic hydrotalcite does not contain impurities and presents a pure white color, the crystal itself is optically transparent, so that when the fine powder is used, it is as high as a silver salt-based photograph. It is possible to form a pigment that achieves saturation.

In addition to the above-mentioned hydrotalcite group minerals, examples of anion-exchangeable intercalation compounds include hydrated oxides such as titanium, zirconium, lanthanum, and bismuth, and hydroxide phosphates. Since it has opacity or a unique color, it can be used when transparency, gloss, and whiteness are not simultaneously required.

The exchangeable anions existing between the layers of the anion-exchangeable intercalation compound as described above are organic compounds that have the effect of increasing the interlayer distance (pillar effect) and the effect of partially hydrophobizing the layers. It may be substituted with an anion. Such organic anions include carboxylate anion, sulfonate anion, ester anion,
And phosphate ester anions. Such anions usually have an alkyl group or an alkenyl group, but when their carbon number is small, the pillar effect is not sufficient, and it becomes difficult to secure the interlayer as a fixing seat (exchangeable inorganic anion). If the amount is too large, it is difficult to substitute, so that the carbon number is preferably 5-20.

When a cation-exchangeable layered compound such as a montmorillonite group mineral is used as an interlayer compound capable of fixing and retaining a dye by an intercalation reaction based on an ion exchange action, an anion such as a hydrotalcite group mineral is used. In any case where the exchangeable layered compound is used, it is preferable that at least a part, ideally all, of the remaining interlayer ions replaced with the dye ions are replaced with the hydrophilic ions. In any case, the replacement amount of the dye ion is preferably 5% or more of the exchange capacity of the interlayer compound. If the replacement amount of the dye ion is less than this, the coloring power becomes insufficient, and the image formed using the pigment ink using this pigment becomes unclear. However, if unadsorbed dye ions remain, the dispersibility of the pigment in water is significantly deteriorated.
In order to obtain a submicron particle size, it is preferable to set the adsorption amount to less than 50% of the exchange capacity, depending on the type of the dye.

When the intercalation compound is made of a montmorillonite group mineral, the dye ion substituted for at least a part of the intercalation ion is preferably a basic dye, in particular, at least one of a cationic dye and a basic direct dye. .

Here, as the cationic dye, an azo dye having an amine salt or a quaternary ammonium group, a triphenylmethane dye, an azine dye, an oxazine dye, a thiazine dye, or the like can be used. These cationic dyes usually have an inorganic anion as a counter ion, and most of them exist as salts of strong acids. Therefore, since the aqueous solution generally shows acidity, it is preferable to neutralize with a basic salt in order to prevent corrosion of the metal member that comes into contact with the ink composition containing such a cationic dye. For example, it is preferable that the inorganic anion as a counter ion is treated with a soda salt of an organic anion such as a carboxylate ion or the like to substitute the organic anion. In this case, in order not to decrease the affinity of the intercalation compound for the cationic dye, it is preferable that the affinity with the intercalation compound is not reduced by salt formation with an organic anion.

Further, as the basic direct dye, trade names:
Pergasol F (manufactured by CibaGeigy), trade name: Cartasol K (manufactured by Sandoz), trade name: Levacell C (manufactured by Bayer), trade name: Fastusol C (manufactured by BASF), and the like.

The remaining interlayer ions which are not replaced by the dye ions as described above are preferably replaced by hydrogen ions. For this purpose, for example, a cation exchange layered compound such as a montmorillonite group mineral may be introduced into a liquid containing hydrochloric acid. When a basic dye such as a basic direct dye or a cationic dye as described above is adsorbed between layers of the montmorillonite group mineral together with hydrogen ions, light resistance can be improved. This is because a basic dye such as a basic direct dye or a cationic dye has a property that light resistance is improved in an acidic atmosphere. Therefore, among the interlayer ions of the montmorillonite group minerals,
Those that are not replaced by the above dyes due to steric hindrance,
It is desirable to be replaced by hydrogen ions as much as possible.

In addition, if the interlayer ions of the montmorillonite group mineral are sufficiently replaced with the above-mentioned dye and hydrogen ions so that other ions are not adsorbed between the layers, when this is used as an ink, water Dispersibility can be appropriately controlled.

On the other hand, when the intercalation compound is composed of a hydrotalcite group mineral, the dye ion to be substituted for at least a part of the intercalation ion is preferably an anionic dye, that is, at least one of a direct dye and an acid dye. is there.

Here, the anionic dye has a chromophore having a monoazo group, a diazo group, an anthraquinone skeleton, a triphenylmethane skeleton, etc.
Those having an anionic water-soluble group such as three sulfonic acid groups or carboxyl groups can be used. These anionic dyes may be retained as they are in the interlayer compound.However, in order to improve the compatibility with alcohols used as auxiliary components of the ink composition and to prevent bleeding, their counter cations are used. May be substituted with an organic cation such as an onium ion. in this case,
In order not to reduce the affinity of the interlayer compound for the anionic dye, it is preferable that the dye is not highly hydrophobicized by salt formation with an organic cation.

The remaining interlayer ions which are not substituted by the dye ions as described above are preferably substituted by an anion of salicylic acid or an isomer thereof or an anion of a salicylic acid derivative having a pKa value of 5.0 or less. . For this purpose, for example, an anion-exchangeable layered compound such as a hydrotaalcite group mineral is swollen in water, and to this solution, salicylic acid or the like corresponding to the exchange capacity is added to reach equilibrium. Good. When an anionic dye such as a direct dye or an acid dye is adsorbed between the layers of the hydrotalcite group minerals together with an anion of salicylic acid or an anion of an isomer thereof or an anion of a salicylic acid derivative having a pKa value of 5.0 or less, the amount of dye adsorbed Is dramatically increased, and light resistance can be improved.

Further, if the interlayer ions of the hydrotalcite group mineral are sufficiently replaced with the above-described anionic dye and aromatic acid so that other ions are not adsorbed between the layers, the ink can be used as an ink. In addition, the dispersibility in water can be appropriately controlled.

In the present invention, when the pigment having the above constitution is used as the intercalation compound made of a montmorillonite group mineral, the average particle size becomes 0.3 μm or less, and the intercalation compound is made of a hydrotalcite group mineral. in case of,
Finely pulverized so that the average particle size becomes 0.25 μm.

For this purpose, in the present invention, at least a part of the interlayer ions in the interlayer compound is replaced with a specific dye ion having a polarity opposite to that of the interlayer ion to obtain a pigment, and then a flow tube type is obtained. Alternatively, an aqueous sand mill is used as a pulverizer, and a fine pulverization process is performed on the aqueous dispersion of the pigment.

Further, such a pulverization treatment is preferably performed as a preliminary pulverization treatment not only after the dye adsorption step but also before the dye adsorption step. Thus, the average particle size of the interlayer compound is preferably set to 0.5 μm or less.

When the preliminary pulverization is not performed, or when the preliminary pulverization is insufficient and the average particle size of the intercalation compound is larger than 0.5 μm, the surface of the large massive intercalation compound is treated with an organic substance in the dye adsorption step. Since a certain paint is coated, not only the amount of the dye introduced into the interlayer compound becomes insufficient, but also in the subsequent pulverization step, sufficient pulverization cannot be performed. On the other hand, in the preliminary pulverization step, when the dye adsorbing step is performed after sufficiently pulverizing the intercalation compound, the dye can be efficiently introduced into the intercalation compound, so that a pigment having excellent coloring properties can be obtained. Also,
In the subsequent pulverization step, efficient pulverization can be performed, so that the average particle size of the pigment finally obtained can be sufficiently reduced. However, when a montmorillonite group mineral is used as the interlayer compound, the viscosity in water is significantly increased, so that it may be difficult to perform a preliminary grinding treatment before the dye adsorption step.

Here, the flow tube type or annular type sand mill used for the fine pulverizing treatment and the preliminary pulverizing treatment is filled with a pulverizing medium inside and pulverized by the shearing force of the pulverizing medium. Flow tube type sand mills are, for example, filled with grinding media in a vertical or horizontal cylindrical tank equipped with a shaft having a stirring disk and pins inside, and the liquid in which the material to be ground is dispersed is continuously filled here. The material to be pulverized is pulverized by feeding the material, and specific examples thereof include a sand grinder, a grain mill, a dyno mill, and a pearl mill. Further, an annular type sand mill fills a narrow space formed by a rotor (some of which has a stirring pin) and a stator with a pulverizing medium, and rotates the rotor so that an object to be pulverized is removed. By continuously feeding the dispersed liquid, the material to be crushed is crushed, and specifically, a conical ball mill, a DCP type pearl mill,
A spike mill and the like.

In the present invention, it is desirable to rotate the crusher at a high speed so that the peripheral velocity of the outer periphery of the stirring disk or the peripheral velocity of the outer periphery of the rotor is 8 to 16 m / sec.

When such a pulverizing apparatus is actually used, a supply tank provided with a stirrer such as a dissolver and the above-mentioned flow tube type or annular type sand mill are installed on a circulation line to carry out circulation processing. The system may be a system capable of performing such a process, or a system capable of performing a continuous process by arranging two or more of the above-described flow tube type or annular type sand mills in series.

In the present invention, as long as the pulverizing apparatus used in the preliminary pulverizing step and the pulverizing apparatus used in the fine pulverizing step have the above-described configuration, even if both are of the same type, different types of It may be in the form.

Here, as the pulverizing medium to be filled in the pulverizing apparatus as described above, in the preliminary pulverizing treatment,
Specific gravity is 3.5 to 8.0, average particle size is 0.8 to 1.6 mm
When the pulverization treatment is performed, the specific gravity is 3.5 to
It is suitable to use those having a mean particle size of 8.0 to 0.2 to 0.8 mm.

If the specific gravity or the average particle size of the pulverizing media is out of the above range, it is impossible to apply a sufficient shearing force, and it is impossible to reduce the final average particle size of the pigment to a desired size. Would.

Examples of the material of the grinding media include various ceramics which are chemically stable and satisfy a specific gravity of 3.5 to 8.0. Specifically, zirconia, titania,
Examples include zircon, alumina, and zirconia reinforced alumina.

In the present invention, since the pigment is wet-pulverized, an aqueous dispersion of the finely divided pigment is obtained after the completion of the pulverization step. Therefore, it can be used as it is as a pigment ink, but in practice,
A pigment ink is obtained by filtering with a filter, adjusting the pigment concentration, and adding a desired additive.

As additives, dispersants, wetting agents, defoaming agents, penetrants, antioxidants, surface tension regulators, viscosity regulators, pH regulators, fungicides, etc. are added as required. Just do it.

Examples of the dispersant include various water-soluble polymer compounds such as polyvinyl alcohol, polyvinylpyrrolidone, methylcellulose, acrylic acid derivatives and polyethylene glycol, and various surfactants such as nonionic surfactants and anionic surfactants. One or more selected from agents may be appropriately selected and used.

When the intercalation compound is made of a montmorillonite group mineral, it is preferable to use, as a dispersant, pyrophosphoric acid or a salt thereof in an amount of 20 to 100% by weight based on the weight of the pigment. When the particles of the intercalation compound are made finer, the viscosity of the pigment ink increases due to swelling of the intercalation compound. However, when pyrophosphoric acid or a salt thereof is added, the viscosity can be reduced due to the dissolving effect. The amount of pyrophosphoric acid or a salt thereof was 20
If the amount is less than 100% by weight, a practical fusing effect cannot be obtained. If the amount exceeds 100% by weight, the solubility limit will be exceeded.

Further, when the intercalation compound is composed of a hydrotalcite group mineral, polyacrylic acid or a salt thereof may be used as a dispersing agent in an amount of 100% by weight or less based on the pigment.
It is preferable to use 1000% by weight. In an intercalation compound composed of hydrotalcite group minerals, if an ion having the same polarity as an adsorbed ion species such as a dye is excessively added, a repulsive force due to a surface charge is generated in the intercalation compound in a complex state, and the intercalation between these intercalation compound particles Aggregation is prevented. Therefore, it is considered that the dispersibility of the interlayer compound is stabilized by adding the above-described compound as a dispersant. If the amount of polyacrylic acid or a salt thereof is less than 100% by weight, a sufficient dispersing effect cannot be obtained.
If it exceeds 0% by weight, the image formed by the pigment ink tends to collapse in water, and the water resistance of the image is impaired.

As the wetting agent, both a heterocyclic ketone and glycerin or a glycerin derivative are preferably used. All of the heterocyclic ketones, glycerin and glycerin derivatives have moisturizing properties, but the heterocyclic ketone has solubility for the dye adsorbed between the interlayer compounds, and glycerin or the glycerin derivative has the solubility for the dye. There is no. For this reason, if only a heterocyclic ketone is used as a wetting agent, the dye will swell by absorbing the dye, and the formed image will be significantly blurred. Further, when only glycerin or a glycerin derivative is used as the wetting agent, the ejection property is deteriorated, the formed image is blurred, and finally, clogging is caused. Therefore, a heterocyclic ketone and glycerin or a glycerin derivative are both used in combination, and the amount of addition needs to be optimized.

The pigment ink may contain a water-soluble organic solvent. For example, alkyl alcohols having 1 to 4 carbon atoms, such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, and isobutyl alcohol. , Polyethylene glycol, polyalkyl alcohols such as polypropylene glycol, ethylene glycol, propylene glycol, butylene glycol, diethylene glycol, etc., alkylene glycols having 2 to 6 alkylene groups, glycerin,
And lower alkyl ethers of polyhydric alcohols such as ethylene glycol methyl ether and diethylene glycol methyl ether.

As described above, by applying the present invention and using a flow tube type or annular type sand mill as a pulverizing apparatus and performing wet pulverization using a pulverizing medium that satisfies the conditions described above, pigments can be shortened. It becomes possible to miniaturize in time.

The pigment ink containing a fine pigment obtained as described above can be effectively used in a wide range of technical fields, but is particularly suitable for application to ink-jet type image recording. When performing this image recording,
A pigment ink may be selectively ejected onto a recording material according to an image signal by using a normal ink jet recording apparatus provided with a bubble driving jet nozzle, a piezo element driving jet nozzle, and the like.

When the pigment ink obtained by the present invention is used for image recording of an ink jet system, clogging of nozzles can be prevented, ejection properties are stable, and an image formed due to excellent pigment coloring property is formed. Are high in print density and clear.

The pigment ink obtained by the present invention uses a dye in which dye ions are firmly fixed between layers of an interlayer compound by an intercalation reaction based on an ion exchange action. Since a dye-receiving layer is not required on the recording material side, an image excellent in storability, fixability, and durability can be formed with a color tone comparable to that of the dye ink, regardless of the recording material. Images formed using this pigment ink have saturation, resolution, and durability comparable to silver halide photographic images, and can be sufficiently used as identification photographs and printed materials for outdoor exhibitions. And its industrial value is very high.

The present invention relates to a method for producing a pigment ink. Needless to say, a finely divided pigment is taken out from the produced pigment ink (aqueous dispersion of the pigment) and used for purposes other than ink. It is also possible to use. For example, the pigment obtained by the present invention can be used as a coloring agent for plastics, a coloring agent for writing instruments such as crayon, a coloring paint, and the like.

[0072]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments to which the present invention is applied will be described below based on experimental results.

Experiment 1 In this experiment, a montmorillonite group mineral having a smectite structure (hereinafter, simply referred to as smectite) was used as an interlayer compound, and the interlayer ions were replaced with dye ions to obtain a pigment. A pigment ink was prepared by performing a fine pulverization process on an aqueous dispersion of the pigment using various pulverizers and pulverization conditions. Then, the difference in the characteristics of the pigment ink due to the difference in the crushing device used for the fine crushing treatment was examined.

[Preparation of Ink Sample] First, a preparation liquid having the following composition was prepared.

1000 parts by weight of ethanol 700 parts by weight of pure water 100 parts by weight of 1 mol / l hydrochloric acid Then, smectite (Laport) was added to this mixed solution.
e, 100 parts by weight of a product, Laponite RDS) were added thereto with stirring, and the mixture was further stirred for 30 minutes to replace interlayer ions in smectite with hydrogen ions. Then, a basic dye (Hodogaya Chemical) was used as a dye. Product name: CATHILON YELLOW 7GLH)
By adding 1000 parts by weight of a% ethanol solution, the interlayer ions of smectite were replaced with dye ions. This allows
An aqueous dispersion of a yellow pigment was obtained.

Thereafter, the aqueous dispersion containing the pigment thus obtained was subjected to dehydration by a filter press treatment, followed by vacuum drying and coarse pulverization to obtain a pigment powder.

Then, the pigment obtained as described above was charged into an aqueous solution having the following composition, and stirred for 60 minutes in a stirring tank provided with a dissolver type stirrer.

Pigment 100 parts by weight 10% aqueous solution of polyvinylpyrrolidone resin (manufactured by BASF, trade name: K-17) 200 parts by weight Pure water 900 parts by weight Polyether polyol 2 parts by weight This gives a preliminary dispersion of the pigment. Was.

<Ink Sample A> Thereafter, the above-mentioned preliminary dispersion liquid is finely pulverized to produce a pigment ink.
As shown in FIG. 1, a system in which a stirring tank 1 provided with a stirrer such as a dissolver and a flow-tube type sand mill 3 are incorporated in a circulation line to perform a circulation process was applied.

The stirring tank 1 in this system is used for obtaining the above-mentioned preliminary dispersion. And
The predispersed liquid stirred here is supplied to the flow tube type sand mill 3 via the pump 2.

On the other hand, the flow tube type sand mill 3 is prepared by filling a pulverizing medium into a horizontal cylindrical tank having a shaft having a stirring disk therein, and continuously feeding the preliminary dispersion liquid into the tank. A pulverization process is performed. The finely pulverized preliminary dispersion liquid is supplied to the stirring tank 1 described above.

As a result, the preliminary dispersion liquid circulates through the inside of the stirring tank 1 and the inside of the flow tube type sand mill 3, so that the stirring and the fine pulverization are repeatedly performed.

Here, as the flow tube type sand mill 3, a product name: LMZ-10 manufactured by Netche Co., Ltd. was used.
The inside was filled with titania beads having a specific gravity of 3.9 and an average particle size of 1.0 mm as a pulverizing medium so as to have a filling rate of 80%. Further, the peripheral speed of the outer periphery of the built-in stirring disk was set to 10 m / sec, and the circulation flow rate of the preliminary dispersion was set to 3
The pulverization treatment was performed under the condition of 00 liter / hour until the average residence time became 40 minutes.

The aqueous dispersion of the pigment thus obtained is stored in a receiving tank 6 as shown in FIG. 1, and 20 parts of diethylene glycol as a wetting agent is added to 100 parts by weight of the aqueous dispersion. 1 part by weight of polyoxyethylene alkyl ether is added as a part by weight and a surface tension modifier. Then, this aqueous dispersion was subjected to an absolute accuracy of 0.8μ.
The pigment ink (referred to as Ink Sample A) was completed by passing through a filter 7 of m at a flow rate of 1 liter / min. In addition, the completed ink sample
Stored in storage tank 8.

<Ink Sample B> Here, after preparing a preliminary dispersion of the pigment as described above, as shown in FIG. 2, the rear side of the stirring tank 1 in which a stirrer such as a dissolver is provided. In addition, by applying a system in which three flow tube type sand mills 3 are arranged in series to perform continuous processing,
A fine grinding treatment was performed.

The stirring tank 1 in this system is used for obtaining a pre-dispersion liquid. The pre-dispersion liquid stirred here is supplied via a pump 2 to a flow tube type sand mill 3 at the most upstream side. It has been made to be.

The structure of each flow tube type sand mill 3 is the same as that of the process for preparing the ink sample A, except that the finely pulverized preliminary dispersion liquid is not returned to the stirring tank 1 but is sequentially passed through the downstream flow tube. It is supplied to the mold sand mill 3.

Thus, the preliminary dispersion is continuously pulverized by the three flow tube type sand mills 3.

Here, as the flow tube type sand mill 3, a Dynomill KDL-15 manufactured by Willy A. Bakkofen Co., Ltd. was used, and the specific gravity was 6.0 and the average particle diameter was as a grinding media inside. Was filled with zirconia beads having a filling ratio of 80%. Further, the peripheral speed of the outer periphery of the built-in stirring disk is set to 1
0 m / sec, and the supply flow rate of the preliminary dispersion liquid was 24 liters /
The pulverization process was performed under the condition of time.

The aqueous dispersion of the pigment thus obtained is stored in a receiving tank 6 as shown in FIG. The agent was added, passed through the filter 7 and stored in the storage tank 8. The pigment ink thus obtained is referred to as an ink sample B.

<Ink Sample C> Here, after preparing the preliminary dispersion of the pigment as described above, as shown in FIG. 3, the rear side of the stirring tank 1 provided with a stirrer such as a dissolver or the like. And an annular sand mill 4 in series with 5
A fine grinding process was performed by applying a system that was provided on a stand and capable of performing continuous processing.

The stirring tank 1 in this system is used for obtaining a pre-dispersion liquid. The pre-dispersion liquid stirred here is supplied via a pump 2 to an annular type sand mill 4 at the most upstream side. It has been made.

The annular type sand mill 4 fills a narrow gap formed by a rotor and a stator with a pulverizing medium, and continuously feeds a liquid in which a substance to be pulverized is dispersed while the rotor is rotated. Thereby, the object to be crushed is crushed. The finely pulverized preliminary dispersion liquid is supplied to the subsequent annular sand mill 4 without returning to the stirring tank 1.

Thus, the preliminary dispersion is continuously pulverized by the five annular sand mills 4.

In this case, the annular type sand mill 4 manufactured by FRYMA, trade name: COBALL-M
Using an ILL type, zircon beads having a specific gravity of 3.9 and an average particle diameter of 1.0 mm were filled therein as pulverization media so as to have a filling rate of 90%. Further, the fine pulverization treatment was performed under the condition that the peripheral speed of the outer periphery of the built-in rotor was 14 m / sec and the supply flow rate of the preliminary dispersion was 10 liter / hour.

The aqueous dispersion of the pigment thus obtained is stored in the receiving tank 6 as shown in FIG. The agent was added, passed through the filter 7 and stored in the storage tank 8. The pigment ink thus obtained is referred to as an ink sample C.

<Ink Sample D> The ink sample C was prepared in the same manner as the ink sample C except that the number of the annular type sand mills 4 provided on the subsequent stage of the stirring tank 1 provided with a stirrer such as a dissolver was one. The same system as used in the production process was applied to perform a fine pulverization process.

The stirring tank 1 and the annular type sand mill 4 in this system have the same configuration as that described in the step of preparing the ink sample C, but here, one preliminary dispersion liquid stirred in the stirring tank 1 is used. It was sent to the only annular type sand mill 4 and pulverized.

The model of the annular type sand mill 4
The specific gravity, average particle diameter,
The filling ratio, various pulverizing conditions, and the like were the same as those in the production process of the ink sample C.

The aqueous dispersion of the pigment thus obtained is pooled in the receiving tank 6 as shown in FIG. The agent was added, passed through the filter 7 and stored in the storage tank 8. The pigment ink thus obtained is referred to as an ink sample D.

<Ink Sample E> In this example, after preparing a preliminary dispersion of the pigment as described above, as shown in FIG. 4, a rear stage side of the stirring tank 1 provided with a stirrer such as a dissolver is provided. Was finely pulverized by the ball mill 10 disposed in the first mill.

The stirring tank 1 was used to obtain a preliminary dispersion, and the stirred preliminary dispersion was supplied to a pump 2.
Through the ball mill 10.

The ball mill 10 is filled with crushing media in a horizontal cylindrical tank, and by rotating the cylindrical tank, the crushing medium moves upward with the movement of the inner wall surface. Is used to obtain a shearing force by utilizing the downward dispersion, and a fine pulverizing treatment is performed by filling the preliminary dispersion liquid in the shearing force.

Here, as the ball mill 10,
The capacity of the cylindrical tank is 30 liters and the rotation speed is 60r
pm, and a steel ball having a specific gravity of 7.85 and an average particle diameter of 6 mm was filled therein as a pulverizing medium so as to have a filling ratio of 50%. Then, the ball mill 10 was filled with 30% of the effective volume of the preliminary dispersion liquid and pulverized for 48 hours.

The aqueous dispersion of the pigment thus obtained is stored in a receiving tank 6 as shown in FIG. 4, and a wetting agent and a surface tension adjusting agent are added in the same manner as in the process of preparing the ink sample A. It was added, passed through the filter 7 and stored in the storage tank 8. The pigment ink thus obtained is referred to as an ink sample E.

<Ink Sample F> Here, after preparing a preliminary dispersion of the pigment as described above, as shown in FIG. 5, the rear side of the stirring tank 1 in which a stirrer such as a dissolver is provided. In addition, by applying a system in which a large number of homogenizers 11 are arranged in series to perform continuous processing,
A fine grinding treatment was performed.

The stirring tank 1 in this system is used for obtaining a pre-dispersion liquid, and the pre-dispersion liquid stirred here is supplied via the pump 2 to the homogenizer 11 at the most upstream stage. Has been made.

The homogenizer 11 is a wet-type emulsifying device, and a fine pulverizing process is performed by continuously feeding the preliminary dispersion liquid. Then, the preliminary dispersion liquid that has been pulverized here is supplied to the homogenizer 11 in the subsequent stage without returning to the stirring tank 1. As a result, the preliminary dispersion liquid is continuously pulverized by the multiple homogenizers 11.

Here, as the homogenizer 11, a colloid mill (trade name, manufactured by GAULIN) was used.
The pulverization process was performed at a rotation speed of 10,000 rpm.

The aqueous dispersion of the pigment thus obtained is stored in a receiving tank 6 as shown in FIG. 5, and a wetting agent and a surface tension adjusting agent are prepared in the same manner as in the process of preparing the ink sample A. It was added, passed through the filter 7 and stored in the storage tank 8. The pigment ink thus obtained is referred to as an ink sample F.

[Evaluation of Characteristics] Here, the average particle size of the pigment contained in each of the ink samples obtained as described above, whether or not clogging occurs in the filtration step at the time of preparation, was determined using an ink jet printer. The stability when ejected and the density of the formed print were investigated.

The average particle size of the pigment was measured with a laser light scattering particle size distribution analyzer (trade name: DLS-700, manufactured by Otsuka Electronics Co., Ltd.).

The presence or absence of clogging in the filtration step was determined by passing a 20 liter ink sample through the filter 7 at a flow rate of 1 liter / minute during the preparation of each ink sample. When clogging does not occur, 、 indicates that clogging occurs (the difference between the pressure before passing through the filter and the pressure after passing through the filter is 3 kg /
cm ² or more) was evaluated as x.

The stability when ejected by an ink-jet printer was determined by using an ink-jet printer (made by Hewlett-Packard, model name: 1200).
C) is filled in the cartridge, and is used to discharge the ink onto the ink jet paper (manufactured by Kao Corporation), print a test pattern, and visually evaluate whether or not each ink sample is stably discharged. did. In addition, the case where stable ejection was performed and no dot defect was not observed was evaluated as O, and the case where ejection was unstable and dot defect and satellite were observed was evaluated as X.

Further, the print density was evaluated by measuring the reflection density with a Macbeth densitometer (TR924) for a high-density image portion obtained by solid printing using each ink sample. It is desirable that the reflection density be 1.2 or more from the viewpoint of the saturation of the print.

Table 1 shows the results of these evaluations for each ink sample.

[0117]

[Table 1]

As shown in Table 1, in ink samples A to D which were finely pulverized using a flow tube type or annular type sand mill, the average particle size of the pigment was 0.3 μm or less in all cases. Also, no clogging of the filter occurred and the ejection stability was excellent. In addition, the reflection density of the print density was 1.2 or more, and sufficient saturation was obtained.

On the other hand, ink samples E and F finely pulverized using a ball mill or a homogenizer were used.
In, the average particle size of the pigment exceeded 0.3 μm, the filter was clogged, and the ejection became unstable. Further, since the print density did not reach the reflection density of 1.2, the saturation was also insufficient.

From these results, it was found that the flow tube type or annular type sand mill is excellent in the fineness efficiency and can uniformly finely size the pigment in a short time.
Then, using such a pulverizer, the average particle diameter of the pigment obtained by adsorbing the dye between the layers of smectite is 0.3 μm.
When it is uniform, the pigment ink having excellent ejection stability can be obtained without causing clogging of nozzles when performing recording by the ink jet system. In addition, it was found that the image formed with the pigment ink had an extremely excellent color developability.

Experiment 2 In this experiment, a hydrotalcite group mineral as an intercalation compound (hereinafter simply referred to as hydrotalcite) was used.
When preparing a pigment ink from a pigment obtained by replacing the interlayer ion with a dye ion, the characteristics of the pigment ink depend on whether or not a preliminary pulverization treatment is performed on an aqueous dispersion of an interlayer compound before the dye adsorption step. Was examined to see if a difference occurred. Further, the difference in the characteristics of the pigment ink due to the difference in the crushing device used for the pre-crushing process and the fine crushing process performed after the dye adsorption step was also examined.

[Preparation of Ink Sample] First, a preparation liquid having the following composition was prepared.

Hydrotalcite 100 parts by weight Pure water 900 parts by weight Polyether polyol 2 parts by weight In addition, calcined hydrotalcite (Kyowa Chemical Industry Co., Ltd., trade name: KW2200) is swollen in water, The exchange capacity of this hydrotalcite (6.7
salicylic acid (pKa = 2.mmmol / g).
81) was added, and the mixture was allowed to stand for 2 days to reach equilibrium, and then the powder was recovered and dried.

Then, the above prepared liquid was stirred for 60 minutes in a stirring tank provided with a dissolver type stirrer. Thus, a preliminary dispersion of hydrotalcite was obtained.

<Ink Sample G> After that, the above-mentioned preliminary dispersion is subjected to preliminary pulverization, dye adsorption, and fine pulverization to produce a pigment ink. In this case, as shown in FIG. These series of processes were performed by applying a simple system.

In this system, a stirring tank 1 provided with a stirrer such as a dissolver and a flow tube type sand mill 3 are incorporated in a circulation line so that a circulation process can be performed. Since this system is the same as that shown in FIG. 1 used for producing the ink sample A, common members are denoted by common symbols, and redundant description will be omitted.

Thus, the preliminary dispersion liquid circulates inside the stirring tank 1 and inside the flow tube type sand mill 3, so that the stirring and the preliminary pulverization are repeatedly performed.

Here, the flow tube type sand mill 3 is
A LMZ-10 model (trade name, manufactured by Netche) was used, and inside thereof, titania beads having a specific gravity of 3.9 and an average particle diameter of 1.0 mm were filled as pulverization media so as to have a filling rate of 80%. Further, the peripheral speed of the outer periphery of the built-in stirring disk was set to 10 m / sec, and the circulation flow rate of the preliminary dispersion liquid was set to 300 m / sec.
Preliminary pulverization was performed under the condition of liter / hour until the average residence time became 10 minutes.

The average particle size of the hydrotalcite in the aqueous dispersion of hydrotalcite thus obtained was 0.39 μm.

Then, as a dye, C.I. I. An operation of adding 6 parts by weight of a 7.5% aqueous solution of Direct Yellow 132 (manufactured by Zeneca Corporation, trade name: IG) with stirring and replacing interlayer ions of hydrotalcite with dye ions for 30 minutes was performed. Thus, an aqueous dispersion of a yellow pigment was obtained.

Thereafter, in order to carry out a fine pulverizing treatment on the aqueous dispersion of the pigment, the pigment was circulated again inside the stirring tank 1 and inside the flow tube type sand mill 3. In addition, this fine pulverization treatment was performed under the same pulverization conditions as in the preliminary pulverization until the average residence time became 40 minutes.

The aqueous dispersion of the pigment thus obtained is stored in a receiving tank 6 as shown in FIG. 6, and 20 parts by weight of diethylene glycol as a wetting agent is added to 100 parts by weight of the aqueous dispersion. 1 part by weight of polyoxyethylene alkyl ether is added as a part by weight and a surface tension modifier. Then, this aqueous dispersion was subjected to an absolute accuracy of 0.8μ.
The pigment ink (referred to as ink sample G) was completed by passing it through the filter 7 at a flow rate of 1 liter / min. In addition, the completed ink sample
Stored in storage tank 8.

<Ink Sample H> Here, the preliminary dispersion of the hydrotalcite obtained as described above is subjected to a preliminary pulverization treatment, a dye adsorption treatment, and a fine pulverization treatment to prepare a pigment ink. At this time, a system as shown in FIG. 7 was applied.

In this system, a flow tube type sand mill 3 for pre-grinding treatment is provided downstream of the stirring tank 1 in which a stirrer such as a dissolver is provided. Further, at the subsequent stage, three flow tube type sand mills 3 for fine pulverization processing are arranged in series to enable continuous processing.

The stirring tank 1 in this system was used to obtain a preliminary dispersion, and the preliminary dispersion thus stirred was passed through a pump 2 to a flow tube type sand mill 3 for preliminary grinding. Are supplied.

The structure of the flow tube type sand mill 3 for the pre-pulverization treatment is the same as that used in the step of preparing the ink sample G, except that the pre-pulverized water dispersion of hydrotalcite is mixed in the stirring tank 1. , And is supplied to the subsequent dye adsorption tank 9 in the subsequent stage.

[0137] Here, as the flow tube type sand mill 3, Dynomill KDL-15 manufactured by Willy A. Bakkofen Co., Ltd. was used. Was filled with zirconia beads having a filling ratio of 80%. Further, the peripheral speed of the outer periphery of the built-in stirring disk is set to 1
0 m / sec, and the supply flow rate of the preliminary dispersion liquid was 24 liters /
Preliminary crushing treatment was performed under the condition of time.

The aqueous dispersion of hydrotalcite thus obtained is stored in the dye adsorption tank 9. At this time, when the average particle size of the hydrotalcite in this aqueous dispersion was measured, it was 0.41 μm.

In the dye adsorption tank 9, an operation of replacing the interlayer ions of hydrotalcite with dye ions was performed in the same manner as in the process of preparing the ink sample G. Thus, an aqueous dispersion of a yellow pigment was obtained.

Thereafter, in order to carry out a fine pulverizing treatment on the aqueous dispersion of the pigment, the aqueous dispersion of the pigment was supplied to a flow tube type sand mill 3 provided at the foremost side in the flow tube type sand mill 3 for the fine pulverizing treatment. .

The structure of each of the flow tube type sand mills 3 for the fine pulverization is the same as that used in the preliminary pulverization.
The aqueous dispersion of the pigment is successively placed in the flow tube type sand mill 3
, A fine pulverization process is continuously performed.

The aqueous dispersion of the pigment thus obtained is stored in the receiving tank 6 as shown in FIG. 7, and the wetting agent and the surface tension adjusting agent are prepared in the same manner as in the process of preparing the ink sample G. The agent was added, passed through the filter 7 and stored in the storage tank 8. The pigment ink thus obtained is referred to as an ink sample H.

<Ink Sample I> In this case, the preliminary dispersion of the hydrotalcite obtained as described above is subjected to a preliminary pulverization treatment, a dye adsorption treatment, and a fine pulverization treatment to prepare a pigment ink. At this time, a system as shown in FIG. 8 was applied.

In this system, two annular sand mills 4 for pre-grinding treatment are arranged in series at the subsequent stage of the stirring tank 1 equipped with a stirrer such as a dissolver, and the dye adsorption treatment is provided at the subsequent stage. A tank 9 and further subsequent stages, four annular sand mills 4 for fine pulverization are arranged in series so that continuous processing can be performed.

The stirring tank 1 in this system is used to obtain a preliminary dispersion, and the pre-dispersion liquid stirred here is passed through a pump 2 to a pre-pulverization side of an annular type sand mill 4 for preliminary pulverization. It is made to supply toward the thing of.

The configuration of the annular type sand mill 4 for the preliminary pulverization is the same as that used for producing the ink sample C. The preliminary dispersion liquid is sequentially sent out from the former-stage annular sand mill 4 to the latter-stage annular sand mill, and is continuously subjected to preliminary pulverization.

Here, the annular type sand mill 4 manufactured by FRYMA, trade name: COBALL-MILL
Using a mold, the specific gravity is 3.
9. Filling ratio of zircon beads having an average particle size of 1.0 mm is 9
It was filled so as to be 0%. Preliminary pulverization was performed under the conditions that the peripheral speed of the outer periphery of the built-in rotor was 14 m / sec and the supply flow rate of the preliminary dispersion was 10 liters / hour.

The aqueous dispersion of hydrotalcite thus obtained is stored in the dye adsorption tank 9. At this time, when the average particle size of the hydrotalcite in this aqueous dispersion was measured, it was 0.35 μm.

In the dye adsorption tank 9, an operation of replacing the interlayer ions of hydrotalcite with dye ions was performed in the same manner as in the process of preparing the ink sample G. Thus, an aqueous dispersion of a yellow pigment was obtained.

Thereafter, in order to carry out a fine pulverizing treatment on the aqueous dispersion of the pigment, the aqueous dispersion of the pigment was supplied to an annular-type sand mill 4 for the pulverizing treatment, which was provided at the most upstream side.

The structure of each of the annular type sand mills 4 for the fine pulverization is the same as that used in the preliminary pulverization, and the aqueous dispersion of the pigment is sequentially supplied to the subsequent annular type sand mill 4. Thereby, a fine pulverization process is continuously performed.

The aqueous dispersion of the pigment thus obtained is stored in the receiving tank 6 as shown in FIG. 8, and the wetting agent and the surface tension adjusting agent are prepared in the same manner as in the process of preparing the ink sample G. The agent was added, passed through the filter 7 and stored in the storage tank 8. The pigment ink thus obtained is referred to as an ink sample I.

<Ink Sample J> In this example, the preliminary dispersion of the hydrotalcite obtained as described above is subjected to a preliminary pulverization treatment, a dye adsorption treatment, and a fine pulverization treatment to prepare a pigment ink. At this time, a system as shown in FIG. 9 was applied.

In this system, a ball mill 10 for pre-grinding treatment is provided at the subsequent stage of the stirring tank 1 (not shown) in which the pre-dispersion liquid of hydrotalcite has been stirred. Further, a ball mill 10 for fine pulverizing processing is provided at a subsequent stage so that a series of processing can be performed.

The stirring tank 1 in this system is used for obtaining a pre-dispersion liquid. The pre-dispersion liquid stirred here is supplied to a ball mill 10 for pre-pulverization treatment via a pump 2.

The configuration of the ball mill 10 for the preliminary pulverizing treatment is the same as that used for producing the ink sample E. Here, a ball mill having a cylindrical tank capacity of 30 liters and a rotation speed of 60 rpm is used as the ball mill 10, and a specific gravity of 7.8 is used as a pulverizing medium therein.
5. Filling rate of steel ball with average particle size of 6mm 50%
It was filled so that Then, 30% of the effective volume of the preliminary dispersion was filled in the ball mill 10, and a preliminary pulverization treatment was performed for 48 hours.

The aqueous dispersion of hydrotalcite thus obtained is stored in the dye adsorption tank 9. At this time, when the average particle size of the hydrotalcite in this aqueous dispersion was measured, it was 0.49 μm.

In the dye adsorption tank 9, an operation of replacing the interlayer ions of hydrotalcite with dye ions was performed in the same manner as in the process of preparing the ink sample G. Thus, an aqueous dispersion of a yellow pigment was obtained.

Thereafter, the aqueous dispersion of the pigment was supplied to a ball mill 10 for the fine pulverization in order to perform the fine pulverization of the aqueous dispersion of the pigment.

The configuration of the ball mill 10 for the fine pulverization is the same as that used for the preliminary pulverization. The aqueous dispersion of the pigment is subjected to the fine pulverization by the ball mill 10.

The aqueous dispersion of the pigment thus obtained is stored in the receiving tank 6 as shown in FIG. The agent was added, passed through the filter 7 and stored in the storage tank 8. The pigment ink thus obtained is referred to as an ink sample J.

<Ink Sample K> In this example, the preliminary dispersion of hydrotalcite obtained as described above was subjected to a dye adsorption treatment and a fine pulverization treatment without performing a preliminary pulverization treatment to obtain a pigment ink. Was prepared. A system as shown in FIG. 10 was applied to this series of processing.

This system is the same as that applied in Comparative Example 3 except that the ball mill for preliminary grinding is omitted, and the system is not shown in the subsequent stage of the stirring tank 1 for stirring the preliminary dispersion of hydrotalcite. On the side, a dye adsorption treatment tank 9 is arranged, and a ball mill 10 for fine pulverization treatment is arranged on the subsequent stage.

In the dye adsorption tank 9, an operation of replacing the interlayer ions of hydrotalcite with dye ions was performed in the same manner as in the preparation process of the ink sample G. Thus, an aqueous dispersion of a yellow pigment was obtained.

Thereafter, the aqueous dispersion of the pigment was supplied to a ball mill 10 for the fine pulverization in order to perform the pulverization of the aqueous dispersion of the pigment. The configuration of the ball mill 10 for the fine pulverization is the same as that used in the preliminary pulverization and the fine pulverization in Comparative Example 3.

The aqueous dispersion of the pigment thus finely pulverized is stored in the receiving tank 6 as shown in FIG. The surface tension modifier was added, passed through the filter 7 and stored in the storage tank 8.
The pigment ink thus obtained was used as an ink sample K
And

<Ink Sample L> In this case, too, the preliminary dispersion liquid of hydrotalcite was subjected to a dye adsorption treatment and a fine pulverization treatment without performing a preliminary pulverization treatment, thereby producing a pigment ink. A system as shown in FIG. 11 was applied to this series of processing.

In this system, a dye adsorption treatment tank 9 and a fine-pulverization apparatus are not provided on the subsequent stage of the stirring tank 1 (not shown) in which the preliminary dispersion of hydrotalcite is stirred. A homogenizer 11 for pulverizing treatment is provided.

In the dye adsorption tank 9, an operation of replacing the interlayer ions of hydrotalcite with dye ions was performed in the same manner as in the preparation process of the ink sample G. Thus, an aqueous dispersion of a yellow pigment was obtained.

Thereafter, the aqueous dispersion of the pigment was supplied to a homogenizer 11 for the fine pulverization in order to perform the fine pulverization of the aqueous dispersion of the pigment. The configuration of the homogenizer 11 for the fine pulverization is the same as that used in the fine pulverization of Comparative Example 2.

The aqueous dispersion of the pigment thus finely pulverized is stored in the receiving tank 6 as shown in FIG. The surface tension modifier was added, passed through the filter 7 and stored in the storage tank 8.
The pigment ink thus obtained was used as an ink sample L
And

[Evaluation of Characteristics] Here, for each of the ink samples obtained as described above, the average particle size of the pigment contained, whether or not clogging occurs in the filtration step during preparation, was determined using an ink jet printer. The stability when ejected and the density of the formed print were investigated.

These evaluation methods are the same as the evaluation method in Experiment 1. Table 2 shows the results of these evaluations for each ink sample.

[0174]

[Table 2]

As shown in Table 2, in the ink samples G to I which had been subjected to preliminary pulverization and fine pulverization using a flow tube type or annular type sand mill, the final average particle size of the pigment Is 0.25 μm or less, and no clogging of the filter occurs.
The ejection stability was also excellent. In addition, the print density was almost satisfactory, and sufficient saturation was obtained.

On the other hand, even if the preliminary pulverization treatment is performed before the dye adsorption treatment, in the ink sample J using a ball mill as the pulverization apparatus, the final average particle size of the pigment exceeds 0.25 μm. As a result, the filter was clogged and the discharge became unstable. In addition, since the print density was insufficient, the saturation was also insufficient.

Further, in the ink samples K and L which were not subjected to the preliminary pulverization before the dye adsorption, the final average particle diameter of the pigment was further increased, so that the filter was clogged and the ink was ejected. The stability also deteriorated.
Further, since the printing density was further insufficient, the saturation was also insufficient.

From these results, it is necessary to carry out a preliminary pulverization treatment before the dye adsorption treatment, and a flow tube type or an annular type sand mill is used for the preliminary pulverization treatment and the fine pulverization treatment. Turned out necessary.

That is, by preliminarily pulverizing before the dye adsorption treatment and making the hydrotalcite finer to 0.5 μm or less, the dye can be efficiently introduced into the hydrotalcite, so that the A pigment excellent in the quality can be obtained. In the subsequent fine pulverization step, efficient pulverization can be performed, so that the average particle size of the pigment finally obtained can be sufficiently reduced. The pigment obtained by adsorbing the dye between the layers of the hydrotalcite has an average particle diameter of 0.1.
When the thickness is 25 μm or less, a pigment ink exhibiting excellent ejection stability can be obtained without causing nozzle clogging when performing recording by an ink jet method. Further, the image formed by this pigment ink has extremely excellent color developability.

Experiment 3 In this experiment, in preparing a pigment ink from a pigment obtained by substituting the interlayer ions of hydrotalcite with dye ions, a preliminary pulverization treatment before the dye adsorption treatment and a post-dye adsorption treatment were performed. It was examined whether or not the characteristics of the produced pigment ink were different due to the difference in the pulverization media used in the fine pulverization performed.

[Preparation of Ink Sample] First, a preliminary dispersion of hydrotalcite was obtained in the same manner as in Experiment 2.

<Ink Sample M> In this example, the obtained preliminary dispersion of hydrotalcite was subjected to preliminary pulverization treatment, dye adsorption treatment, and fine pulverization treatment to prepare a pigment ink. The system as shown was applied. This system is as described in the process of producing the ink sample H.

In order to perform a series of processes as described above, first, the preliminary dispersion is preliminarily pulverized for the preliminary dispersion of hydrotalcite stirred in the stirring tank 1. It was supplied to a flow tube type sand mill 3 for processing. Here, as the flow tube type sand mill 3, a product name: Dynomill KDL-15 manufactured by Willy A. Bakkofen Co., Ltd., and a specific gravity of 6.0 and an average particle diameter of 1.25 mm are used as grinding media therein. Of zirconia beads (manufactured by Toray Industries, Inc.) to a filling rate of 80%. Further, the pre-pulverization treatment was performed under the condition that the peripheral speed of the outer periphery of the built-in stirring disk was 10 m / sec and the supply flow rate of the pre-dispersion liquid was 24 liter / hour.

The aqueous dispersion of hydrotalcite thus obtained is stored in the dye adsorption tank 9. And
In the dye adsorption tank 9, an operation of replacing interlayer ions of hydrotalcite with dye ions was performed. This allows
An aqueous dispersion of a yellow pigment was obtained.

Thereafter, in order to carry out a fine pulverizing treatment on the aqueous dispersion of the pigment, the aqueous dispersion of the pigment was supplied to a flow tube type sand mill 3 provided at the foremost stage in the flow tube type sand mill 3 for the fine pulverizing treatment. . Then, the aqueous dispersion of the pigment is successively supplied to the downstream-side flow tube type sand mill 3 so that the pigment is continuously pulverized.

The structure of each of the flow tube type sand mills 3 for fine pulverization is the same as that used in the preliminary pulverization, but the inside thereof has a specific gravity of 6.0 and an average particle size of 0. .
5 mm zirconia beads (manufactured by Toray Industries, Inc.) were filled as pulverization media so that the filling rate was 80%.

The aqueous dispersion of the pigment thus obtained is stored in a receiving tank 6 as shown in FIG. 7, and a wetting agent and a surface tension adjusting agent are added thereto.
And stored in the storage tank 8. The pigment ink thus obtained is referred to as an ink sample M.

<Ink Sample N> Here, the specific gravity and the average particle size of the pulverization media used for the preliminary pulverization processing and the fine pulverization processing were different from those of the ink sample M manufacturing process.

That is, the pulverization medium to be filled in the flow tube type sand mill 3 for the pre-pulverization treatment was changed to titania beads (manufactured by Toyama Ceramic Co., Ltd.) having a specific gravity of 3.9 and an average particle diameter of 1.4 mm. Except for changing the pulverizing media to be filled in the flow tube type sand mill 3 for processing to titania beads having a specific gravity of 3.9 and an average particle diameter of 0.8 mm (manufactured by Toyama Ceramic Co., Ltd.), all processes for preparing the ink sample M In the same manner as described above, a pigment ink was produced. This is designated as ink sample N.

<Ink Sample O> Also in this case, the specific gravity and the average particle diameter of the pulverization media used for the preliminary pulverization processing and the fine pulverization processing were different from those of the ink sample M manufacturing process.

That is, the pulverization medium to be filled in the flow tube type sand mill 3 for the preliminary pulverization processing was changed to zircon beads (manufactured by SEPR) having a specific gravity of 3.8 and an average particle diameter of 1.4 mm. The grinding media to be filled into the flow tube type sand mill 3 for use is a specific gravity of 3.8 and an average particle size of 0.7 mm.
Except for the zircon beads (SEPR)
A pigment ink was produced in the same manner as in the production process of the ink sample M. This is designated as ink sample O.

<Ink Sample P> Also in this case, the specific gravity and the average particle diameter of the pulverizing media used in the preliminary pulverization processing and the fine pulverization processing were different from those in the manufacturing process of the ink sample M.

That is, the grinding media to be filled in the flow tube type sand mill 3 for the preliminary grinding treatment was changed to soda glass beads (manufactured by Toshiba Barotini) having a specific gravity of 2.5 and an average particle size of 3.0 mm. Except for changing the pulverization medium to be filled in the flow tube type sand mill 3 for pulverization processing to soda glass beads (manufactured by Toshiba Barotini) having a specific gravity of 2.5 and an average particle diameter of 1.5 mm, all of the ink samples M A pigment ink was produced in the same manner as in the production process. This is designated as ink sample P.

<Ink Sample Q> Also in this case, the specific gravity and the average particle diameter of the pulverizing media used in the preliminary pulverization processing and the fine pulverization processing were made different from those in the ink sample M manufacturing process.

That is, the crushing medium to be charged into the flow tube type sand mill 3 for the preliminary crushing treatment was changed to zirconia beads (manufactured by Toray Industries, Inc.) having a specific gravity of 6.0 and an average particle diameter of 2.0 mm, and the fine crushing treatment was performed. Of the ink sample M except that the crushing media to be filled in the flow tube type sand mill 3 for use was changed to zirconia beads having a specific gravity of 6.0 and an average particle size of 2.0 mm (manufactured by Toray Industries, Inc.). Thus, a pigment ink was prepared. This is designated as ink sample Q.

<Ink Sample R> Also in this case, the specific gravity and the average particle size of the pulverization media used in the preliminary pulverization processing and the fine pulverization processing were different from those of the ink sample M manufacturing process.

That is, the grinding media to be filled in the flow tube type sand mill 3 for the preliminary grinding treatment was changed to a crystalline glass bead (manufactured by OHARA) having a specific gravity of 3.2 and an average particle diameter of 1.3 mm. The pulverization medium to be filled in the flow tube type sand mill 3 for pulverization treatment has a specific gravity of 3.2 and an average particle size of 1.0 m.
A pigment ink was produced in the same manner as in the production process of the ink sample M, except that the crystalline glass bead m (manufactured by OHARA) was changed to m. This is designated as ink sample R.

[Evaluation of Characteristics] Here, for each of the ink samples obtained as described above, the average particle size of the pigment contained, whether or not clogging occurs in the filtration step during preparation, was determined using an ink jet printer. The stability when ejected and the density of the formed print were investigated.

These evaluation methods are the same as the evaluation method in Experiment 1. Table 3 shows the results of these evaluations for each ink sample.

[0200]

[Table 3]

As shown in Table 3, the ink sample M
-O, the final average particle size of the pigment was 0.25 µm or less, and no clogging of the filter occurred, and the ejection stability was excellent. In addition, the print density was almost satisfactory, and sufficient saturation was obtained. On the other hand, in the ink samples P to R,
The average particle size of the final pigment exceeds 0.25 μm,
Either clogging of the filter, unstable ejection, or insufficient print density occurred.

The ink samples M to O satisfy the specific gravity of the pulverization medium used in the preliminary pulverization process of 3.5 to 8.0 and the average particle diameter of 0.8 to 1.6 mm, and are used in the pulverization process. The media has a specific gravity of 3.5 to 8.0 and an average particle size of 0.2.
Since the ink samples P to R did not satisfy the above-described range, the pre-crushing process and the fine pulverizing process used a pulverizing medium satisfying the above-described conditions. It turned out to be necessary.

That is, by making hydrotalcite sufficiently fine in the pre-pulverization treatment before the dye adsorption treatment, the dye can be efficiently introduced into the hydrotalcite, so that a pigment having excellent coloring properties can be obtained. Will be obtained. Also, in the subsequent fine pulverization step, efficient pulverization can be performed. Then, if the average particle diameter of the pigment obtained by adsorbing the dye between the layers of hydrotalcite is made uniform by 0.25 μm or less by a fine pulverization treatment after the dye adsorption treatment, when performing the recording by the ink jet method, the nozzle It is possible to obtain a pigment ink exhibiting excellent ejection stability without causing clogging. Further, the image formed by this pigment ink has extremely excellent color developability.

As described above, from Experiments 1 to 3, in order to produce a pigment ink composed of a uniformly finely divided pigment, the pigment was adsorbed using a flow tube type or annular type sand mill after the step of adsorbing the dye to the interlayer compound. It was found that it was necessary to carry out a fine pulverization treatment on the aqueous dispersion of.
Prior to the dye adsorption step, a preliminary pulverization treatment is performed on the aqueous dispersion of the intercalation compound using a flow tube type or an annular type sand mill so that the average particle size of the intercalation compound is 0.5 μm or less. Was found to be preferable. Furthermore, it was found that it is preferable to optimize the specific gravity and the average particle size of the pulverizing media in the pre-pulverizing treatment and the fine pulverizing treatment.

When the intercalation compound is smectite, the final pigment has an average particle size of 0.3 μm or less, and when the intercalation compound is hydrotalcite. In the case where the final pigment has an average particle diameter of 0.25 μm or less, a pigment ink showing excellent ejection stability without causing clogging of nozzles when performing ink jet recording. It was also found that the image formed with this pigment ink had extremely excellent color developability.

[0206]

As is clear from the above description, when the present invention is applied, it is possible to manufacture a pigment ink comprising a pigment which is uniformly finely divided.

Therefore, for example, when the ink jet recording is performed using this pigment ink, excellent ejection stability is exhibited without causing nozzle clogging. Further, the image formed by this pigment ink has extremely excellent color developability.

[Brief description of the drawings]

FIG. 1 is a schematic diagram for explaining a system used for producing an ink sample A.

FIG. 2 is a schematic diagram for explaining a system used for producing an ink sample B.

FIG. 3 is a schematic diagram for explaining a system used for producing an ink sample C;

FIG. 4 is a schematic diagram for explaining a system used for producing an ink sample E;

FIG. 5 is a schematic diagram for explaining a system used for producing an ink sample F.

FIG. 6 is a schematic diagram for explaining a system used for producing an ink sample G;

FIG. 7 is a schematic diagram for explaining a system used for producing an ink sample H;

FIG. 8 is a schematic diagram for explaining a system used for producing an ink sample I.

FIG. 9 is a schematic diagram for explaining a system used for producing an ink sample J.

FIG. 10 is a schematic diagram for explaining a system used for producing an ink sample K.

FIG. 11 is a schematic diagram for explaining a system used for producing an ink sample L.

[Explanation of symbols]

1 stirring tank, 3 flow tube type sand mill, 4 annular type sand mill, 7 filter, 9 dye adsorption tank, 10 ball mill, 11 homogenizer

Claims (6)

[Claims] 1. A dye adsorption step of replacing at least a part of interlayer ions in an interlayer compound with a specific dye ion having a polarity opposite to that of the interlayer ions to obtain a pigment, and a flow tube type or annular type sand mill. A finely pulverizing step of performing finely pulverizing treatment on the aqueous dispersion of the pigment using the above as a pulverizing device. 2. A flow tube type or annular type sand mill is used as a pulverizer before the dye adsorption step,
The method for producing a pigment ink according to claim 1, further comprising a pre-pulverization step of performing a pre-pulverization process on the aqueous dispersion of the intercalation compound. 3. The method for producing a pigment ink according to claim 2, wherein the average particle size of the intercalation compound is reduced to 0.5 μm or less by the preliminary pulverization treatment. 4. The pre-grinding treatment has a specific gravity of 3.5 to 3.5.
8.0, the pulverization medium having an average particle diameter of 0.8 to 1.6 mm is filled in the pulverizer, and the fine pulverization treatment has a specific gravity of 3.5 to 8.0 and an average particle diameter of 0.8 to 1.6 mm. 0.2-0.
3. The method for producing a pigment ink according to claim 2, wherein the method is performed in a state in which a grinding medium of 8 mm is filled in the grinding device. 5. A montmorillonite group mineral having a smectite structure is used as the intercalation compound, and a pigment is obtained by using at least one of a basic direct dye and a cationic dye as the dye ion. Average particle size of 0.30 μm
2. The method for producing a pigment ink according to claim 1, wherein: 6. A pigment is obtained by using a hydrotalcite group mineral as the intercalation compound, and using at least one of a direct dye and an acidic dye as the dye ion, and obtaining an average particle size of the pigment by the fine pulverization treatment. 0.25 μm
2. The method for producing a pigment ink according to claim 1, wherein: