JP2009126993A - Method for manufacturing pigment dispersion and pigment dispersion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pigment dispersion excellent in dispersion stability of pigment particles over a long period of time (long-term dispersion stability), and to provide a method for manufacturing a pigment dispersion by which a pigment dispersion excellent in dispersion stability of pigment particles over a long period of time (long-term dispersion stability) can be manufactured. <P>SOLUTION: The method for manufacturing a pigment dispersion includes: a preliminary dispersion step of obtaining a dispersant dispersion liquid having a dispersant dispersed in a solvent by stirring a mixture containing the dispersant, a dispersion resin and the solvent; and a fine dispersion step of adding a pigment to the dispersant dispersion liquid and adding inorganic beads in a multi-stage process to carry out fine dispersion process. The fine dispersion process is preferably carried out in a multi-stage process of performing primary fine dispersion by using first inorganic beads having a predetermined particle diameter and then adding second inorganic beads having a particle diameter smaller than the first inorganic beads. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing a pigment dispersion and a pigment dispersion.

In general, pigments have a feature that they are superior in weather resistance and the like than dyes, and pigment dispersions containing organic pigments are widely used for paint applications and the like.
Conventionally, various dispersing agents have been used in organic pigment dispersions for the purpose of improving the dispersibility of pigment particles. However, even in a pigment dispersion containing a dispersant, the dispersibility of the pigment decreases with time, so that, for example, a coating film having a uniform color density or a coating film having a uniform film thickness is formed. There are problems such as uneven color and uneven density in the formed coating film.
For the purpose of solving the above problems, there is an attempt to treat organic pigment powder with a hydrophobic surface treatment agent (see, for example, Patent Document 1), but such a hydrophobic surface treatment agent is used. Even in this case, it was difficult to make the dispersibility of the pigment sufficiently excellent for a long period of time.

JP 2007-197545 A

  An object of the present invention is to provide a pigment dispersion excellent in long-term dispersion stability (long-term dispersion stability) of organic pigment (hereinafter simply referred to as pigment) particles, and to provide long-term dispersion stability of pigment particles. Another object of the present invention is to provide a method for producing a pigment dispersion capable of producing a pigment dispersion having excellent properties (long-term dispersion stability).

Such an object is achieved by the present invention described below.
The method for producing a pigment dispersion according to the present invention comprises a preliminary dispersion step of obtaining a dispersant dispersion in which the dispersant is dispersed in the solvent by stirring a mixture containing the dispersant, the dispersion resin, and the solvent. When,
And a fine dispersion step of adding a pigment to the dispersant dispersion and adding inorganic beads in multiple stages to carry out a fine dispersion treatment.
Thereby, the manufacturing method of the pigment dispersion which can manufacture the pigment dispersion excellent in the dispersion stability (long-term dispersion stability) over the long term of a pigment particle can be provided.

In the method for producing a pigment dispersion of the present invention, the fine dispersion treatment is performed by performing a primary fine dispersion treatment using the first inorganic beads having a predetermined particle size, and then having a particle size smaller than that of the first inorganic beads. It is preferable to add two inorganic beads and carry out in multiple stages.
Thereby, the long-term dispersion stability of the pigment particles in the pigment dispersion can be made particularly excellent.

In the method for producing a pigment dispersion of the present invention, the average particle size of the first inorganic beads is 0.5 to 2.0 mm, and the average particle size of the second inorganic beads is 0.03 to 0.30 mm. It is preferable that
Thereby, the long-term dispersion stability of the pigment particles in the pigment dispersion can be made particularly excellent. Further, the pigment dispersion can be produced efficiently, and the productivity of the pigment dispersion can be made particularly excellent.

In the method for producing a pigment dispersion of the present invention, it is preferable that the fine dispersion treatment is performed in two stages, that is, a treatment using the first inorganic beads and a treatment using the second inorganic beads.
Thereby, the long-term dispersion stability of the pigment particles in the pigment dispersion can be made particularly excellent. Further, the productivity of the pigment dispersion can be made particularly excellent.
In the method for producing a pigment dispersion of the present invention, it is preferable to use 1,3-butylene glycol diacetate and / or diethylene glycol dibutyl ether as the solvent.
Thereby, the long-term dispersion stability of the pigment particles in the pigment dispersion can be made particularly excellent. Further, the pigment dispersion can be produced efficiently, and the productivity of the pigment dispersion can be made particularly excellent.

In the method for producing a pigment dispersion of the present invention, the pigment is C.I. I. Pigment red 177, C.I. I. Pigment red 177 and derivatives thereof, C.I. I. Pigment red 254, and C.I. I. Pigment Red 254 and derivatives thereof are preferably selected.
Thereby, the long-term dispersion stability of the pigment particles in the pigment dispersion can be made particularly excellent.

In the method for producing a pigment dispersion of the present invention, the pigment is C.I. I. Pigment green 58 or C.I. I. Pigment Green 58 and other pigment derivatives are preferable.
C. I. Although Pigment Green 58 has a feature of excellent lightness, it has been extremely difficult to stably disperse it in the pigment dispersion by the conventional method. On the other hand, in the present invention, it is extremely difficult to stably disperse C.I. I. Even when the pigment green 58 is included, the long-term dispersion stability in the pigment dispersion can be made particularly excellent. That is, the pigment is C.I. I. Pigment green 58 or C.I. I. By using Pigment Green 58 and other pigment derivatives, the effects of the present invention are more remarkably exhibited.

In the method for producing a pigment dispersion of the present invention, the pigment is C.I. I. Pigment blue 15: 6 or C.I. I. Pigment blue 15: 6 and C.I. I. It is preferably a pigment blue 15 derivative.
Thereby, the long-term dispersion stability of the pigment particles in the pigment dispersion can be made particularly excellent.

The pigment dispersion of the present invention is characterized by being produced using the method of the present invention.
Thereby, the pigment dispersion excellent in the dispersion stability (long-term dispersion stability) of pigment particles over a long period of time can be provided.
In the pigment dispersion of the present invention, the pigment content is 10 wt% or more, the viscosity at 25 ° C. is 12 mPa · s or less, and
The amount of change in viscosity at 25 ° C. after standing for 7 days in an environment of 40 ° C. is preferably 0.5 mPa · s or less.
Thereby, for example, the occurrence of uneven color and uneven density when a coating film is formed using a pigment dispersion can be reliably prevented over a long period of time.

  According to the present invention, it is possible to provide a pigment dispersion excellent in dispersion stability (long-term dispersion stability) of pigment particles over a long period of time, and to provide long-term dispersion stability (long-term dispersion stability) of pigment particles. A method for producing a pigment dispersion capable of producing an excellent pigment dispersion can be provided.

Hereinafter, preferred embodiments of the present invention will be described.
First, a preferred embodiment of the method for producing a pigment dispersion of the present invention will be described.
≪Method for producing pigment dispersion≫
The method for producing a pigment dispersion of the present invention comprises a preliminary dispersion step of obtaining a dispersant dispersion in which a dispersant is dispersed in a solvent by stirring a mixture containing a dispersant, a dispersion resin, and a solvent. A fine dispersion step of adding a pigment to the dispersant dispersion and adding inorganic beads in multiple stages to carry out a fine dispersion treatment.

<Preliminary dispersion process>
In the preliminary dispersion step, a dispersion containing a dispersant dispersed in a solvent is prepared by stirring a mixture containing the dispersant, the dispersion resin, and the solvent. Thereby, it can be set as the state which the association state of the dispersing agent was released.
As described above, in the present invention, prior to the treatment for finely dispersing the pigment, which will be described in detail later, a pigment dispersion in which pigment particles are uniformly and stably dispersed by preliminarily dispersing the mixture containing no pigment. Can be obtained.

[Dispersant]
The dispersant is a component that contributes to improving the dispersibility of the pigment particles in the pigment dispersion. Further, by using a dispersant, the dispersant adheres to the surface of pigment particles (relatively large pigment particles that are not finely dispersed) added to the dispersant dispersion in the fine dispersion step described later. (Adsorption) and the dispersibility of the pigment particles (pigment particles having a relatively large particle size that are not finely dispersed) in the dispersant dispersion can be made excellent. Thereby, the fine dispersion process in the fine dispersion step can be efficiently performed, the productivity of the pigment dispersion can be made particularly excellent, and the pigment particles (fine particles in the finally obtained pigment dispersion can be obtained. The long-term dispersion stability of the dispersed pigment fine particles) can be made excellent.

  Although it does not specifically limit as a dispersing agent, For example, a polymeric dispersing agent can be used. Examples of the polymer dispersant include basic polymer dispersants, neutral polymer dispersants, acidic polymer dispersants, and the like. Examples of such polymeric dispersants include, for example, dispersants made of acrylic and modified acrylic copolymers, urethane dispersants, polyaminoamide salts, polyether esters, phosphate esters, and aliphatic polycarboxylic acids. And the like, and the like.

  More specific examples of the dispersant include, for example, Dispersic 101, Dispersic 102, Dispersic 103, Dispersic P104, Dispersic P104S, Dispersic 220S, Dispersic 106, Dispersic 108, Dispersic 109, Disperse BIC 110, DISPERBIC 111, DISPERBIC 112, DISPERBIC 116, DISPERBIC 140, DISPERBIC 142, DISPERBIC 160, DISPERBIC 161, DISPERBIC 162, DISPERBIC 163, DISPERBIC 164, DISPERBIC 166, DISPERBIC 167 Dispersic 168, Dispersic 170, Dispersic 171, Dispersic 1 4, Dispersic 180, Dispersic 182, Dispersic 183, Dispersic 184, Dispersic 185, Dispersic 2000, Dispersic 2001, Dispersic 2050, Dispersic 2070, Dispersic 2095, Dispersic 2150, Dispersic LPN6919, Dispersic 9075, Dispersic 9077 (above, manufactured by BYK Chemie); EFKA 4008, EFKA 4009, EFKA 4010, EFKA 4015, EFKA 4020, EFKA 4046, EFKA 4047, EFKA 4050, EFKA 4055, EFKA 4055, EFKA 4055 , EFKA 4401, EFKA 4402, EF A 4403, EFKA 4406, EFKA 4408, EFKA 4300, EFKA 4330, EFKA 4340, EFKA 4015, EFKA 4800, EFKA 5010, EFKA 5065, EFKA 5066, EFKA 5070, EFKA 5070, EFKA 5070 Sol Sparse 3000, Sol Sparse 9000, Sol Sparse 13000, Sol Sparse 16000, Sol Sparse 17000, Sol Sparse 18000, Sol Sparse 20000, Sol Sparse 21000, Sol Sparse 24000, Sol Sparse 26000, Sol Sparse 27000, Sol Sparse 28000, Sol Sparse 32000, Sol Sparse 32500, Sol Sparse 32550, Sol Sparse 33500, Solsperse 35100, Solsperse 35200, Solsperse 36000, Solsperse 36600, Solsperse 38500, Solsperse 41000, Solsperse 41090, Solsperse 20000 (above, manufactured by Lubrizol); Manufactured by Ajinomoto Fine Techno Co., Ltd.); Disparon 1850, Disparon 1860, Disparon 2150, Disparon 7004, Disparon DA-100, Disparon DA-234, Disparon DA-325, Disparon DA-375, Disparon DA-705, Disparon DA-725, Disparon PW-36 (above, manufactured by Enomoto Kasei Co., Ltd.) And Florene DOPA-14, Florene DOPA-15B, Floren DOPA-17, Floren DOPA-22, Floren DOPA-44, Floren TG-710, Floren D-90 (manufactured by Kyoei Chemical Co., Ltd.), Anti-Terra-205 (Made by Big Chemie) etc. are mentioned, It can use combining 1 type (s) or 2 or more types selected from these.

  In particular, in the present invention, as the dispersant, a dispersant having a predetermined acid value (hereinafter also referred to as an acid value dispersant) and a dispersant having a predetermined amine value (hereinafter also referred to as an amine value dispersant) It is preferable to use together. As a result, the effect of the acid value dispersant that exhibits the viscosity reduction effect that lowers the viscosity of the pigment dispersion and the effect of the amine value dispersant that stabilizes the viscosity of the pigment dispersion are both compatible. The dispersion stability of the pigment can be made particularly excellent. In particular, in the present invention, prior to performing the fine dispersion treatment of the pigment, a dispersion containing the dispersant is dispersed in the solvent by stirring a mixture containing the dispersant, the dispersion resin, and the solvent. It has a preliminary dispersion step. In such a method, by using an acid value dispersant and an amine value dispersant in combination, the association of the dispersant (association of the acid value dispersant and the amine value dispersant) is reliably prevented, and the dispersion of the pigment is stabilized. The property can be made particularly excellent. On the other hand, when an acid value dispersant and an amine value dispersant are used in combination in a method that does not have a preliminary dispersion step, the excellent effects as described above cannot be obtained. This is considered to be due to the following reasons. That is, even if an acid value dispersant and an amine value dispersant are used in combination, if the preliminary dispersion step is omitted, the acid value dispersant and the amine value dispersant are brought into contact with the pigment particles in an associated state. This is considered to be because aggregation of pigment particles is induced.

  Specific examples of the acid value dispersant include Dispersic P104, Dispersic P104S, Dispersic 220S, Dispersic 110, Dispersic 111, Dispersic 170, Dispersic 171, Dispersic 174, Dispersic 2095 (above, BYC Chemie) EFKA 5010, EFKA 5065, EFKA 5066, EFKA 5070, EFKA 7500, EFKA 7554 (above, manufactured by Ciba Specialty); Solsperse 3000, Solsperse 16000, Solsperse 17000, Solsperse 18000, Solsperse 36000, Solsperse 36000, (Above, manufactured by Lubrizol).

  Specific examples of the amine value dispersant include Dispersic 102, Dispersic 160, Dispersic 161, Dispersic 162, Dispersic 163, Dispersic 164, Dispersic 166, Dispersic 167, Dispersic 168, Dispersic 2150, Dispersic LPN6919, Dispersic 9075, Dispersic 9077 (above, manufactured by BYK Chemie); EFKA 4015, EFKA 4020, EFKA 4046, EFKA 4047, EFKA 4050, EFKA 4055, EFKA 4060, EFKA 4060, EFKA 4060, EFKA 4060, , EFKA 4340, EFKA 4400, EFKA 4401, EFKA 4402, EFK A4403, EFKA 4800 (manufactured by Ciba Specialty Company); Azisper PB711 (manufactured by Ajinomoto Fine-Techno Company); Anti-Terra-205 (manufactured by Big Chemie Company) and the like.

  When the acid value dispersant and the amine value dispersant are used in combination, the acid value of the acid value dispersant (acid value when converted to solid content) is not particularly limited, but is preferably 5 to 370 KOHmg / g. It is more preferably 20 to 270 KOH mg / g, and further preferably 30 to 135 KOH mg / g. When the acid value of the acid value dispersant is within the above range, the dispersion stability of the pigment when used in combination with the amine value dispersant can be made particularly excellent. The acid value of the dispersant can be determined by a method based on DIN EN ISO 2114, for example.

Moreover, it is preferable that the acid value dispersant does not have a predetermined amine value, that is, the amine value is zero.
When the amine value dispersant and the acid value dispersant are used in combination, the amine value of the amine value dispersant (amine value in terms of solid content) is not particularly limited, but is preferably 5 to 200 KOHmg / g. It is more preferably 25 to 170 KOH mg / g, and further preferably 30 to 130 KOH mg / g. When the amine value of the amine value dispersant is a value within the above range, the dispersion stability of the pigment when used in combination with the acid value dispersant can be made particularly excellent. The amine value of the dispersant can be determined by a method based on DIN 16945, for example.

Moreover, it is preferable that the amine value dispersant does not have a predetermined acid value, that is, the acid value is zero.
When the acid value dispersant and the amine value dispersant are used in combination, the use ratio of the acid value dispersant and the amine value dispersant (the use ratio when converted to solid content) is 1: 1 to 1 by weight. It is preferably 1: 9, more preferably 1: 2 to 1: 5. Thereby, the dispersion stability of the pigment in the pigment dispersion can be made particularly excellent.

The effect of using the acid value dispersant and the amine value dispersant in combination as described above is that the pigment is C.I. I. In the case of pigment green 58 and other pigment derivatives (in the case of a mixture of CI pigment green 58 and other pigment derivatives), it becomes particularly remarkable.
The content of the dispersant in the dispersant dispersion prepared in this step (when using a plurality of types of dispersants in combination) is not particularly limited, but is 10 to 40 wt%. Is preferable, and it is more preferable that it is 12-32 wt%. When the content of the dispersant is a value within the above range, the effects as described above are more remarkably exhibited.

[Dispersion resin]
The dispersion resin has a function of improving the dispersibility of the pigment particles, and forms a part of the coating film during molding.
In particular, in the present invention, before the pigment particles (pigment particles having a relatively large particle size that are not finely dispersed) are added, the dispersion resin is mixed with the dispersant and the solvent to thereby add a fine particle to be described later. In the dispersion step, the dispersant and the dispersion resin are adhered to the surface of the pigment particles (pigment particles having a relatively large particle size that are not finely dispersed) added to the dispersant dispersion liquid, and the pigment particles (finely dispersed The pigment particles having a relatively large particle size) can be made excellent in dispersibility in the dispersant dispersion. Thereby, the fine dispersion process in the fine dispersion step can be efficiently performed, the productivity of the pigment dispersion can be made particularly excellent, and the pigment particles (fine particles in the finally obtained pigment dispersion can be obtained. The long-term dispersion stability of the dispersed pigment fine particles) can be made excellent.

Examples of the dispersion resin include alginic acids, polyvinyl alcohol, hydroxypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, methyl cellulose, styrene-acrylic acid resin, styrene-acrylic acid-acrylic acid ester resin, styrene-maleic acid resin, styrene-maleic acid. Acid half ester resin, methacrylic acid-methacrylic ester resin, acrylic acid-acrylic ester resin, isobutylene-maleic resin, rosin modified maleic resin, polyvinylpyrrolidone, gum arabic starch, polyallylamine, polyvinylamine, polyethyleneimine etc. 1 type selected from these, or 2 or more types can be used in combination.
Although the content rate of the dispersion resin in the dispersing agent dispersion liquid prepared at this process is not specifically limited, It is preferable that it is 6-30 wt%, and it is more preferable that it is 8-26 wt%. When the content of the dispersion resin is a value within the above range, the effects as described above are more remarkably exhibited.

[solvent]
The solvent functions as a solvent for dissolving the dispersion resin in the dispersion medium dispersion, and functions as a dispersion medium for dispersing the pigment in the final pigment dispersion.
In the present invention, an aqueous solvent is preferably used as the solvent.
Examples of the water-soluble organic solvent include C1-C4 alkyl alcohols such as ethanol, methanol, butanol, propanol, and isopropanol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and ethylene glycol monomethyl ether. Acetate, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, diethylene glycol mono-n-butyl ether , Triethylene glycol mono-n-butyl ether Ethylene glycol mono-t-butyl ether, diethylene glycol mono-t-butyl ether, 1-methyl-1-methoxybutanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl Ether, propylene glycol mono-iso-propyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-iso-propyl ether, propylene glycol mono-n- Glycol ethers such as butyl ether and dipropylene glycol mono-n-butyl ether, form Bromide, acetamide, dimethyl sulfoxide, sorbitol, sorbitan, acetin, diacetin, triacetin, sulfolane, and the like, may be used alone or in combination of two or more selected from these.

In the present invention, a high-boiling water-soluble organic solvent having a boiling point of 180 ° C. or higher can be used for the purpose of preventing unintended viscosity changes due to evaporation of the solvent during storage of the pigment dispersion.
Specific examples of the water-soluble organic solvent having a boiling point of 180 ° C. or higher include ethylene glycol, propylene glycol, diethylene glycol, pentamethylene glycol, trimethylene glycol, 2-butene-1,4-diol, 2-ethyl-1,3- Hexanediol, 2-methyl-2,4-pentanediol, tripropylene glycol monomethyl ether, dipropylene glycol monoethyl glycol, dipropylene glycol monoethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol, triethylene glycol monomethyl ether, Tetraethylene glycol, triethylene glycol, diethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl Ether, tripropylene glycol, polyethylene glycol having a molecular weight of 2000 or less, 1,3-propylene glycol, isopropylene glycol, isobutylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1, Examples include 6-hexanediol, glycerin, mesoerythritol, pentaerythritol, 1,3-butylene glycol diacetate and diethylene glycol dibutyl ether, and one or two or more selected from these can be used in combination. Among these high-boiling organic solvents, 1,3-butylene glycol diacetate and / or diethylene glycol dibutyl ether is preferably used as the solvent. Thereby, the long-term dispersion stability of the pigment particles in the pigment dispersion can be made particularly excellent. Even when the pigment content in the finally obtained pigment dispersion is increased, the long-term dispersion stability of the pigment can be sufficiently improved. Further, the pigment dispersion can be produced efficiently, and the productivity of the pigment dispersion can be made particularly excellent. The above effects are particularly prominent when 1,3-butylene glycol diacetate is used among 1,3-butylene glycol diacetate and diethylene glycol dibutyl ether.

Although the content rate of the solvent in the dispersing agent dispersion liquid prepared at this process is not specifically limited, It is preferable that it is 40-80 wt%, and it is more preferable that it is 53-75 wt%. When the content of the solvent is within the above range, the effects as described above are more remarkably exhibited.
The amount of the solvent used is not particularly limited, but it is usually preferred that the final pigment dispersion is such that the solvent content relative to 100 parts by weight of pigment is 100 to 500 parts by weight. It is more preferable that the amount is ˜300 parts by weight, and it is even more preferable that the amount is 100 to 200 parts by weight. If the amount of the solvent used is too small, it may be difficult to uniformly disperse the pigment fine particles in the fine dispersion step described later. On the other hand, when the amount of the solvent used is too large, it becomes difficult to sufficiently improve the strength of the film formed using the pigment dispersion finally obtained.

In this step, a dispersant dispersion is obtained by stirring the mixture of the above components using various stirrers.
Examples of the stirrer that can be used in this step include a uniaxial or biaxial mixer such as a disper mill.
Although the stirring process time using a stirrer is not specifically limited, It is preferable that it is 1 to 30 minutes, and it is more preferable that it is 3 to 20 minutes. Thereby, while making the productivity of the pigment dispersion sufficiently excellent, the association state of the dispersant can be solved more effectively, and the dispersion stability of the pigment particles in the finally obtained pigment dispersion can be improved. It can be made particularly excellent.

  Moreover, the rotation speed of the stirring blade which the stirrer has in this step is not particularly limited, but is preferably 500 to 4000 rpm, and more preferably 800 to 3000 rpm. Thereby, while making the productivity of the pigment dispersion sufficiently excellent, the association state of the dispersant can be solved more effectively, and the dispersion stability of the pigment particles in the finally obtained pigment dispersion can be improved. It can be made particularly excellent. In addition, it is possible to reliably prevent deterioration or modification of the dispersion resin due to heat or the like.

<Fine dispersion process>
Next, a pigment is added to the dispersant dispersion obtained in the above step, and inorganic beads are added in multiple stages to perform fine dispersion treatment (fine dispersion step).
The present invention is characterized in that, prior to the addition of the pigment, a preliminary dispersion step as described above is provided, and inorganic beads are added in multiple stages in the step of finely dispersing the pigment (fine dispersion step).

By adding inorganic beads in multiple stages in the fine dispersion step, the efficiency of pigment atomization can be improved, and the pigment particles in the finally obtained pigment dispersion are made sufficiently small. be able to.
On the other hand, when the fine dispersion step is not performed in multiple stages, the above effects cannot be obtained. That is, if the fine dispersion step is not performed in multiple stages, the pigment particles in the finally obtained pigment dispersion cannot be made sufficiently small, or the productivity of the pigment dispersion is significantly reduced. . In addition, even if the pigment particles in the finally obtained pigment dispersion can be made to have a relatively small particle size by extremely increasing the treatment time of the fine dispersion step, In this case, the dispersion resin or the like as described above is deteriorated, modified, etc., and as a result, a pigment dispersion having desired characteristics, particularly a pigment dispersion excellent in long-term dispersion stability of pigment particles is obtained. I can't do that.

  Even if the fine dispersion step is performed in multiple stages, the following problems occur when the preliminary dispersion step as described above is omitted. That is, when the preliminary dispersion step is omitted, when the pigment is added, since the association state of the dispersant is not sufficiently undissolved (not loosened), in the fine dispersion step, the dispersant is applied to the surface of the pigment particles. Therefore, it becomes difficult to uniformly disperse the dispersed resin. In addition, it is difficult to make the dispersibility of the pigment particles in the fine dispersion step (pigment particles that are not finely dispersed and have a relatively large particle size) sufficiently excellent in the solvent. Accordingly, it is difficult to atomize and finely disperse the pigment particles in the fine dispersion step. In addition, even if the pigment particles in the finally obtained pigment dispersion can be made to have a relatively small particle size by extremely increasing the treatment time of the fine dispersion step, In this case, the dispersion resin or the like as described above is deteriorated, modified, etc., and as a result, a pigment dispersion having desired characteristics, particularly a pigment dispersion excellent in long-term dispersion stability of pigment particles is obtained. I can't do that.

  This step may be performed by adding inorganic beads in multiple stages, and may be performed by adding inorganic beads in three or more stages, but it is preferable to add inorganic beads in two stages. . Thereby, the productivity of the pigment dispersion can be made particularly excellent while sufficiently improving the long-term dispersion stability of the pigment particles in the finally obtained pigment dispersion.

In the following description, the method of adding the inorganic beads in two stages, that is, the first treatment using the first inorganic beads and the second treatment using the second inorganic beads in the fine dispersion step. The method of performing will be described representatively.
The inorganic beads (first inorganic beads, second inorganic beads) used in this step may be composed of any material as long as they are composed of an inorganic material. Examples include beads made of zirconia (for example, Toray ceram pulverized ball (trade name), manufactured by Toray Industries, Inc.).

[First processing]
In this step, first, a pigment is added to the dispersant dispersion prepared in the above-described preliminary dispersion step, and a first treatment is performed in which primary fine dispersion is performed using first inorganic beads having a predetermined particle size.
The first inorganic beads used in the first treatment are preferably those having a larger particle size than the second inorganic beads used in the second treatment. Thereby, the efficiency of the atomization (fine dispersion) of the pigment as the whole fine dispersion process can be made particularly excellent.

  The average particle size of the first inorganic beads is not particularly limited, but is usually 0.5 to 3.0 mm, preferably 0.5 to 2.0 mm, and preferably 0.5 to 1.2 mm. Is more preferable. When the average particle diameter of the first inorganic beads is a value within the above range, the efficiency of pigment atomization (fine dispersion) as a whole fine dispersion step can be made particularly excellent. On the other hand, if the average particle size of the first inorganic beads is less than the lower limit, the efficiency of atomization (small particle size) of the pigment particles in the first treatment is remarkably depending on the type of pigment and the like. A tendency to decline appears. When the average particle size of the first inorganic beads exceeds the upper limit, the efficiency of atomization (reduction in particle size) of the pigment particles in the first treatment can be made relatively excellent. However, the efficiency of the atomization (small particle size) of the pigment particles in the second treatment is lowered, and the efficiency of the atomization (fine dispersion) of the pigment as the entire fine dispersion process is lowered.

The amount of the first inorganic beads used is not particularly limited, but is preferably 100 to 600 parts by weight and more preferably 200 to 500 parts by weight with respect to 100 parts by weight of the dispersant dispersion.
As the pigment added to the dispersant dispersion in this step, various organic pigments and various inorganic pigments can be used, but organic pigments are preferable. By using an organic pigment, for example, the color developability of a coating film formed using a pigment dispersion can be made particularly excellent. Examples of organic pigments include compounds classified as Pigments in the Color Index (CI; issued by The Society of Dyers and Colorists), specifically, the following Color Index (CI) numbers: Can be mentioned. More specifically, examples of the organic pigment include C.I. I. Pigment yellow 1, C.I. I. Pigment yellow 3, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 16, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 20, C.I. I. Pigment yellow 24, C.I. I. Pigment yellow 31, C.I. I. Pigment yellow 55, C.I. I. Pigment yellow 60, C.I. I. Pigment yellow 61, C.I. I. Pigment yellow 65, C.I. I. Pigment yellow 71, C.I. I. Pigment yellow 73, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 81, C.I. I. Pigment yellow 83, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 95, C.I. I. Pigment yellow 97, C.I. I. Pigment yellow 98, C.I. I. Pigment yellow 100, C.I. I. Pigment yellow 101, C.I. I. Pigment yellow 104, C.I. I. Pigment yellow 106, C.I. I. Pigment yellow 108, C.I. I. Pigment yellow 109, C.I. I. Pigment yellow 110, C.I. I. Pigment yellow 113, C.I. I. Pigment yellow 114, C.I. I. Pigment yellow 116, C.I. I. Pigment yellow 117, C.I. I. Pigment yellow 119, C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 126, C.I. I. Pigment yellow 127, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 129, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 139, C.I. I. Pigment yellow 150, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 152, C.I. I. Pigment yellow 153, C.I. I. Pigment yellow 154, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 156, C.I. I. Pigment yellow 166, C.I. I. Pigment yellow 168, C.I. I. Pigment yellow 175; C.I. I. Pigment orange 1, C.I. I. Pigment orange 5, C.I. I. Pigment orange 13, C.I. I. Pigment orange 14, C.I. I. Pigment orange 16, C.I. I. Pigment orange 17, C.I. I. Pigment orange 24, C.I. I. Pigment orange 34, C.I. I. Pigment orange 36, C.I. I. Pigment orange 38, C.I. I. Pigment orange 40, C.I. I. Pigment orange 43, C.I. I. Pigment orange 46, C.I. I. Pigment orange 49, C.I. I. Pigment orange 51, C.I. I. Pigment orange 61, C.I. I. Pigment orange 63, C.I. I. Pigment orange 64, C.I. I. Pigment orange 71, C.I. I. Pigment orange 73; C.I. I. Pigment violet 1, C.I. I. Pigment violet 19, C.I. I. Pigment violet 23, C.I. I. Pigment violet 29, C.I. I. Pigment violet 32, C.I. I. Pigment violet 36, C.I. I. Pigment violet 38; C.I. I. Pigment red 1, C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 4, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 8, C.I. I. Pigment red 9, C.I. I. Pigment red 10, C.I. I. Pigment red 11, C.I. I. Pigment red 12, C.I. I. Pigment red 14, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 17, C.I. I. Pigment red 18, C.I. I. Pigment red 19, C.I. I. Pigment red 21, C.I. I. Pigment red 22, C.I. I. Pigment red 23, C.I. I. Pigment red 30, C.I. I. Pigment red 31, C.I. I. Pigment red 32, C.I. I. Pigment red 37, C.I. I. Pigment red 38, C.I. I. Pigment red 40, C.I. I. Pigment red 41, C.I. I. Pigment red 42, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 48: 2, C.I. I. Pigment red 48: 3, C.I. I. Pigment red 48: 4, C.I. I. Pigment red 49: 1, C.I. I. Pigment red 49: 2, C.I. I. Pigment red 50: 1, C.I. I. Pigment red 52: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 57: 2, C.I. I. Pigment red 58: 2, C.I. I. Pigment red 58: 4, C.I. I. Pigment red 60: 1, C.I. I. Pigment red 63: 1, C.I. I. Pigment red 63: 2, C.I. I. Pigment red 64: 1, C.I. I. Pigment red 81: 1, C.I. I. Pigment red 83, C.I. I. Pigment red 88, C.I. I. Pigment red 90: 1, C.I. I. Pigment red 97, C.I. I. Pigment red 101, C.I. I. Pigment red 102, C.I. I. Pigment red 104, C.I. I. Pigment red 105, C.I. I. Pigment red 106, C.I. I. Pigment red 108, C.I. I. Pigment red 112, C.I. I. Pigment red 113, C.I. I. Pigment red 114, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 144, C.I. I. Pigment red 146, C.I. I. Pigment red 149, C.I. I. Pigment red 150, C.I. I. Pigment red 151, C.I. I. Pigment red 166, C.I. I. Pigment red 168, C.I. I. Pigment red 170, C.I. I. Pigment red 171, C.I. I. Pigment red 172, C.I. I. Pigment red 174, C.I. I. Pigment red 175, C.I. I. Pigment red 176, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. Pigment red 179, C.I. I. Pigment red 180, C.I. I. Pigment red 185, C.I. I. Pigment red 187, C.I. I. Pigment red 188, C.I. I. Pigment red 190, C.I. I. Pigment red 193, C.I. I. Pigment red 194, C.I. I. Pigment red 202, C.I. I. Pigment red 206, C.I. I. Pigment red 207, C.I. I. Pigment red 208, C.I. I. Pigment red 209, C.I. I. Pigment red 215, C.I. I. Pigment red 216, C.I. I. Pigment red 220, C.I. I. Pigment red 224, C.I. I. Pigment red 226, C.I. I. Pigment red 242, C.I. I. Pigment red 243, C.I. I. Pigment red 245, C.I. I. Pigment red 254, C.I. I. Pigment red 255, C.I. I. Pigment red 264, C.I. I. Pigment red 265; C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4, C.I. I. Pigment blue 15: 6, C.I. I. Pigment blue 60; I. Pigment green 7, C.I. I. Pigment green 36; C.I. I. Pigment green 58; C.I. I. Pigment brown 23, C.I. I. Pigment brown 25; C.I. I. Pigment Black 1, Pigment Black 7, and derivatives thereof can be used, and one or more selected from these can be used in combination.

In particular, the pigment is C.I. I. Pigment red 177, C.I. I. Pigment red 177 and derivatives thereof, C.I. I. Pigment red 254, and C.I. I. In the case of CI Pigment Red 254 and its derivatives, C.I. I. Pigment red 177 and its derivatives, and C.I. I. In the case of Pigment Red 254 and derivatives thereof, a red pigment dispersion excellent in color developability can be obtained. Further, the long-term dispersion stability of the pigment particles in the pigment dispersion can be made particularly excellent.
For example, when the pigment (red pigment) contains a compound (derivative) represented by the following formula (I) or the following formula (II), fine dispersion of pigment particles when the production method of the present invention is applied In particular, the long-term dispersion stability of the pigment particles in the pigment dispersion can be made particularly excellent.

  The pigment is C.I. I. Pigment Green 58 (brominated zinc phthalocyanine pigment), or C.I. I. By using Pigment Green 58 and other pigment derivatives (derivatives of pigments having other chemical structures), a green pigment dispersion excellent in color developability can be obtained. In addition, C.I. I. Although Pigment Green 58 has a feature of excellent lightness, it has been extremely difficult to stably disperse it in the pigment dispersion by the conventional method. On the other hand, in the present invention, it is extremely difficult to stably disperse C.I. I. Even when the pigment green 58 is included, the long-term dispersion stability in the pigment dispersion can be made particularly excellent. That is, the pigment is C.I. I. Pigment green 58 or C.I. I. By using Pigment Green 58 and other pigment derivatives (derivatives of pigments having other chemical structures), the effects of the present invention are more remarkably exhibited. Such an effect is obtained when the pigment is C.I. I. This is particularly noticeable when pigment green 58 and other pigment derivatives are used.

  The pigment is C.I. I. In the case of pigment green 58 and other pigment derivatives, it is preferable to contain a compound (derivative) represented by the following formula (III) as the other pigment derivative. Thereby, when the production method of the present invention is applied, the fine dispersion efficiency of the pigment particles can be made particularly excellent, and the long-term dispersion stability of the pigment particles in the pigment dispersion is made particularly excellent. be able to.

  The pigment is C.I. I. Pigment blue 15: 6 and C.I. I. By using a pigment blue 15 derivative, a blue pigment dispersion excellent in color developability can be obtained. Further, the long-term dispersion stability of the pigment particles in the pigment dispersion can be made particularly excellent. Such an effect is obtained when the pigment is C.I. I. Pigment blue 15: 6 and C.I. I. This is particularly noticeable when it is a pigment blue 15 derivative.

The amount of the pigment added to the dispersant dispersion is not particularly limited, but is preferably 12 parts by weight or more, and more preferably 18 to 35 parts by weight with respect to 100 parts by weight of the dispersant dispersion.
The first treatment can be performed by stirring using various stirrers in a state where the pigment and the first inorganic beads are added to the dispersant dispersion.

Examples of the stirrer that can be used in the first treatment include a media-type disperser such as a pearl mill, a uniaxial or biaxial mixer such as a disper mill, and the like.
The stirring process time using the stirrer (the processing time of the first process) is not particularly limited, but is preferably 10 to 120 minutes, and more preferably 15 to 40 minutes. Thereby, the atomization (fine dispersion) of a pigment can be advanced efficiently, without reducing the productivity of a pigment dispersion.

  Moreover, the rotation speed of the stirring blade which the stirrer has in the first treatment is not particularly limited, but is preferably 1000 to 5000 rpm, and more preferably 1200 to 3800 rpm. Thereby, the atomization (fine dispersion) of the pigment can proceed more efficiently without reducing the productivity of the pigment dispersion. In addition, it is possible to reliably prevent deterioration or modification of the dispersion resin due to heat or the like.

[Second processing]
After performing the first treatment, the second treatment using the second inorganic beads is performed. Thereby, a pigment dispersion in which pigment particles are sufficiently finely dispersed is obtained.
The second treatment may be performed in a state including the first inorganic beads, but it is preferable to remove the first inorganic beads prior to the second treatment. Thereby, the efficiency of the atomization (fine dispersion) of the pigment in the second treatment can be made particularly excellent. The removal of the first inorganic beads can be easily and reliably performed by a method such as filtration.

  It is preferable that the second inorganic beads used in the second treatment have a smaller particle diameter than the first inorganic beads used in the first treatment. As a result, the pigment in the finally obtained pigment dispersion can be sufficiently atomized (finely dispersed), and the dispersion stability of pigment particles in the pigment dispersion over a long period of time (long-term dispersion stability) Property).

  The average particle size of the second inorganic beads is not particularly limited, but is preferably 0.03 to 0.3 mm, and more preferably 0.05 to 0.2 mm. When the average particle size of the second inorganic beads is within the above range, the efficiency of pigment atomization (fine dispersion) as a whole fine dispersion step can be made particularly excellent. On the other hand, if the average particle size of the second inorganic beads is less than the lower limit value, the efficiency of atomization (reduction in particle size) of the pigment particles in the second treatment is remarkably depending on the type of pigment or the like. A tendency to decline appears. If the average particle size of the second inorganic beads exceeds the upper limit, it may be difficult to sufficiently advance the atomization (fine dispersion) of the pigment particles.

Although the usage-amount of a 2nd inorganic bead is not specifically limited, It is preferable that it is 100-600 weight part with respect to 100 weight part of dispersing agent dispersion liquid, and it is more preferable that it is 200-500 weight part.
The second treatment can be performed using various stirrers.
Examples of the stirrer that can be used in the second treatment include a media type disperser such as a pearl mill, a uniaxial or biaxial mixer such as a disper mill, and the like.

The stirring time using the stirrer (second processing time) is not particularly limited, but is preferably 10 to 120 minutes, and more preferably 15 to 40 minutes. Thereby, the atomization (fine dispersion) of the pigment can be sufficiently advanced without reducing the productivity of the pigment dispersion.
Moreover, the rotation speed of the stirring blade which the stirrer in the second treatment has is not particularly limited, but is preferably 1000 to 5000 rpm, and more preferably 1200 to 3800 rpm. Thereby, the atomization (fine dispersion) of the pigment can proceed more efficiently without reducing the productivity of the pigment dispersion. In addition, it is possible to reliably prevent deterioration or modification of the dispersion resin due to heat or the like.

In the above description, the case where fine dispersion processing is performed in two stages has been mainly described, but three or more stages of processing may be performed. In such a case, it is preferable that the inorganic beads used in the subsequent treatment have a smaller particle diameter than the inorganic beads used in the previous treatment. In other words, the average particle diameter of the inorganic beads (n-th inorganic beads) used in the n-th stage treatment is that of the inorganic beads ((n-1) inorganic beads) used in the (n-1) -stage treatment. It is preferably smaller than the average particle size. By satisfying such a relationship, the efficiency of atomization (fine dispersion) of the pigment particles can be made particularly excellent, and the particle size of the pigment particles in the finally obtained pigment dispersion can be further increased. It can be small.
In the fine dispersion step (for example, the first process and the second process), for example, a process such as dilution with a solvent may be performed as necessary.

≪Pigment dispersion≫
By the method as described above, the pigment dispersion of the present invention is obtained.
In the pigment dispersion of the present invention, the pigment particles are uniformly finely dispersed, and the pigment particles are excellent in dispersion stability (long-term dispersion stability) over a long period of time. For this reason, the characteristic change with time of the pigment dispersion is effectively prevented, and for example, it is suitably applied to the formation of a coating film having a uniform color concentration, a coating film having a uniform film thickness, etc. over a long period of time. It is possible to effectively prevent color unevenness and density unevenness in the formed coating film. In addition, since the pigment particles are finely dispersed, the color developability of the pigment is excellent, and for example, it can be suitably used for forming a coating film with high brightness.

  The pigment content in the pigment dispersion is preferably 10 wt% or more, and more preferably 10 to 25 wt%. Thus, when the pigment content is sufficiently high, for example, the color density of the coating film formed using the pigment dispersion can be made particularly high. Further, the amount of the pigment dispersion required to form a coating film having a predetermined film thickness and color density can be reduced, which is advantageous from the viewpoint of resource saving. Moreover, since the volatilization amount of the solvent at the time of forming the coating film can be suppressed, the burden on the environment can be reduced.

  The viscosity of the pigment dispersion at 25 ° C. (viscosity (kinematic viscosity) measured using an E-type viscometer) is preferably 17 mPa · s or less, preferably 12 mPa · s or less, and 8 to 11 mPa -More preferably, it is s or less. Thus, when the viscosity (kinematic viscosity) of the pigment dispersion is sufficiently low, for example, the coating film formation efficiency can be made particularly excellent, and the thickness of the coating film is unwilling. Can be effectively prevented. If the viscosity of the pigment dispersion is too low, for example, it may be difficult to make the coating film formed using the pigment dispersion sufficiently thick. The viscosity (kinematic viscosity) of the pigment dispersion can be measured using, for example, an E-type viscometer (for example, RE-01 manufactured by Toki Sangyo Co., Ltd.), and in particular, according to JIS Z8809. be able to.

  The amount of change in the viscosity of the pigment dispersion at 25 ° C. (viscosity (kinematic viscosity) measured using an E-type viscometer) after standing for 7 days in an environment of 40 ° C. is 0.5 mPa · It is preferably s or less, and more preferably 0.3 mPa · s or less. As described above, when the pigment dispersion has a sufficiently small change in characteristics (the durability of the pigment dispersion is excellent), for example, color unevenness when a coating film is formed using the pigment dispersion. Further, the occurrence of uneven density can be more reliably prevented over a long period of time.

The pigment dispersion of the present invention contains a pigment, a dispersant, a dispersion resin, and a solvent, but may contain other components as necessary. Examples of such components include vehicles, pH adjusters, antioxidants, ultraviolet absorbers, preservatives, and antifungal agents.
The pigment dispersion of the present invention can be used, for example, for various paints, various printing inks such as offset printing and gravure printing, film colorants, lens coating materials, and the like. The application is not limited to the above examples.

≪Coating film≫
The pigment dispersion as described above can be used for forming a coating film, for example. As described above, since the pigment dispersion of the present invention has finely dispersed pigment particles and can maintain excellent dispersion stability over a long period of time, the pigment dispersion in the pigment dispersion Uneven distribution can be prevented, and the coating film formed using the pigment dispersion of the present invention has excellent film thickness uniformity, and the occurrence of uneven color and uneven density is reliably prevented. Moreover, according to this invention, such a high quality coating film can be formed stably over a long period of time.
For example, the coating film is applied with a pigment dispersion on the substrate by a method such as bar coating, spin coating, roll coating, slit coating, brush coating, offset printing, or gravure printing, and then dried (de-coated) as necessary. The target coating film can be formed by solvent treatment.

Next, specific examples of the present invention will be described.
1. Preparation of pigment dispersion (Example 1)
Dispersic 162: 25.01 g (69 parts by weight) as a dispersant, Dispersic 111: 8.33 g (23 parts by weight) as a dispersant, and SPCN-17X (manufactured by Showa Polymer Co., Ltd.) as a dispersing resin : 19.53 g (54 parts by weight) and 1,3-butylene glycol diacetate as a solvent: 91.14 g (253 parts by weight) were charged into a stirrer (single screw mixer) with an internal capacity of 400 cc. A dispersant dispersion was obtained by stirring for 10 minutes and performing preliminary dispersion (preliminary dispersion step). At this time, the rotation speed of the stirring blade of the stirrer was set to 2000 rpm.

Next, as described below, a fine dispersion step was performed in which a pigment was added to the dispersant dispersion obtained in the preliminary dispersion step, and inorganic beads were added in multiple stages for fine dispersion treatment.
First, 355.99 g (100 parts by weight) of pigment was added to the obtained dispersant dispersion and stirred for 10 minutes. At this time, the rotation speed of the stirring blade of the stirrer was set to 2000 rpm. As the pigment, C.I. I. A powder composed of CI Pigment Red 177, whose surface is composed of a pigment derivative represented by the following formula (I): 17.99 g, mainly C.I. I. A mixture of powder composed of CI Pigment Red 254 and a powder composed of a pigment derivative represented by the following formula (II) in the vicinity of the surface thereof was used. Moreover, it diluted with the 1, 3- butylene glycol diacetate as a solvent so that the content rate of the pigment in the mixture of a dispersing agent dispersion liquid and a pigment might be 15 wt% at this time.

Next, 720 g of inorganic beads having an average particle diameter of 0.8 mm (first inorganic beads, manufactured by zirconia, “Toray ceramic pulverized ball” (trade name), manufactured by Toray Industries, Inc.): 30 minutes at room temperature The first dispersion process (first process) was performed with stirring. At this time, the rotation speed of the stirring blade of the stirrer was set to 2000 rpm.
Next, the inorganic beads (first inorganic beads) are removed by filtration using a filter (“PALL HDCII Membrane Filter”, manufactured by PALL), and then inorganic beads having a mean particle diameter of 0.1 mm (second Inorganic beads, manufactured by zirconia, “Toray ceramic pulverized ball” (trade name), manufactured by Toray Industries, Inc.): 720 g was added, and the mixture was further stirred for 30 minutes to perform the second stage dispersion treatment (second treatment). At this time, the rotation speed of the stirring blade of the stirrer was set to 2000 rpm. Moreover, it diluted with the 1, 3- butylene glycol diacetate as a solvent so that the content rate of the pigment in the pigment dispersion finally obtained might be 10 wt% at this time.
Thereafter, the inorganic beads (second inorganic beads) were removed by filtration using a filter (“PALL HDCII Membrane Filter” (trade name), manufactured by PALL) to obtain a target pigment dispersion.

(Examples 2 to 10)
Example 1 except that the types and amounts of materials used for preparing the pigment dispersion and the treatment conditions of the fine dispersion step (first treatment, second treatment) were changed as shown in Tables 1 and 2. A pigment dispersion was prepared in the same manner as described above.

(Comparative Example 1)
A pigment dispersion was prepared in the same manner as in Example 1 except that the preliminary dispersion step was omitted.
(Comparative Example 2)
The pigment dispersion was carried out in the same manner as in Example 1 except that the processing time of the first stage dispersion process (first process) was 60 minutes and the second stage dispersion process (second process) was omitted. The body was prepared.

(Comparative Example 3)
The pigment is the same as in Example 1 except that the first stage dispersion process (first process) is omitted and the second stage dispersion process (second process) is performed for 60 minutes. A dispersion was prepared.
(Comparative Example 4)
As shown in Table 1, a pigment dispersion was prepared in the same manner as in Comparative Example 3 except that the amount of each component used was changed.

  Table 1 summarizes the composition of the dispersant dispersion, the type of pigment added to the dispersant dispersion, and the amount used in each of the above Examples and Comparative Examples. In Table 1, C.I. I. Pigment Red 177 is “PR177”, C.I. I. Pigment Red 254 is "PR254", C.I. I. Pigment Green 36 is “PG36”, C.I. I. Pigment Green 58 is changed to “PG58”, C.I. I. Pigment Blue 15: 6 is “PB15: 6”, mainly C.I. I. A powder composed of CI Pigment Red 177, the surface of which is composed of a pigment derivative represented by the above formula (I) is referred to as “PR177D”, mainly C.I. I. The powder composed of CI Pigment Red 254, the surface of which is composed of the pigment derivative represented by the above formula (II) is composed of “PR254D” and the pigment derivative represented by the following formula (III). Powder “PYD”, 1,3-butylene glycol diacetate “S1”, diethylene glycol dibutyl ether “S2”, tripropylene glycol monomethyl ether “S3”, Dispersic 162 “DA1”, Dispersic 163 “ DA2 ”, EFKA 4300 is indicated by“ DA3 ”, Dispersic 111 is indicated by“ DA4 ”, and SPCN-17X is indicated by“ DR1 ”. Table 1 also shows the acid value and amine value (acid value when converted to solid content, amine value) of the dispersant. In addition, the value calculated | required by the method based on DIN EN ISO 2114 was shown in the column of an acid value, and the value calculated | required by the method based on DIN 16945 was shown in the column of an amine value. The production conditions for the pigment dispersions of the respective Examples and Comparative Examples are summarized in Table 2. Table 2 also shows the pigment content at the end of the first treatment and at the end of the second treatment (final pigment dispersion).

2. Evaluation of Pigment Dispersion The pigment dispersions obtained in the above Examples and Comparative Examples were evaluated by the following tests.
2-1. Viscosity The pigment dispersions of the above Examples and Comparative Examples were measured for viscosity (kinematic viscosity) and evaluated according to the following five-stage criteria. The viscosity was measured in an environment of 25 ° C. using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., RE-01) according to JIS Z8809.

A: The viscosity is 8 mPa · s or more and less than 11 mPa · s.
B: The viscosity is 11 mPa · s or more and less than 12 mPa · s.
C: The viscosity is 12 mPa · s or more and less than 17 mPa · s.
D: The viscosity is 17 mPa · s or more and less than 20 mPa · s.
E: The viscosity is 20 mPa · s or more.

2-2. Appearance change after heat treatment The pigment dispersions of the above Examples and Comparative Examples were allowed to stand for 7 days in an environment of 40 ° C., then visually observed and evaluated according to the following four-stage criteria.
A: No change from before heating is observed.
B: Slight aggregation / precipitation of pigment particles is observed.
C: Aggregation / sedimentation of pigment particles is clearly observed.
D: Aggregation / sedimentation of pigment particles is noticeable.

2-3. Viscosity change amount With respect to the pigment dispersions of the respective Examples and Comparative Examples, the viscosity (kinematic viscosity) after being allowed to stand for 7 days in an environment of 40 ° C. was measured. The difference from the “viscosity” was determined. That is, when the viscosity immediately after production is ν ₀ [mPa · s] and the viscosity after standing for 7 days in an environment of 40 ° C. is ν ₁ [mPa · s], it is represented by ν ₁ −ν _0. The value was determined. The values thus obtained were evaluated according to the following five-stage criteria. The viscosity was measured in an environment of 25 ° C. using an E-type viscometer (manufactured by Toki Sangyo Co., Ltd., RE-01) according to JIS Z8809.

A: The value of ν ₁ −ν ₀ is less than 0.2 mPa · s.
B: The value of ν ₁ −ν ₀ is 0.2 mPa · s or more and less than 0.3 mPa · s.
C: The value of ν ₁ −ν ₀ is 0.3 mPa · s or more and less than 0.5 mPa · s.
D: The value of ν ₁ −ν ₀ is 0.5 mPa · s or more and less than 0.7 mPa · s.
E: The value of ν ₁ −ν ₀ is 0.7 mPa · s or more.

3. Evaluation of coating film Pigment dispersion obtained in each of the above Examples and Comparative Examples (pigment dispersion immediately after production), and pigment dispersion left in a 40 ° C. environment for 7 days (left in a heating environment) The coating film formed using the (pigment dispersion) was evaluated by the following test.
<Production of evaluation sheet>
Prior to performing each test, an evaluation sheet was prepared by the method described below.
First, a large number of 0.3 mm thick polyimide film films (30 cm × 30 cm) were prepared.

Next, with a bar coater, on each main surface of the polyimide film film, the pigment dispersions of the respective Examples and Comparative Examples (pigment dispersions immediately after production, and left in a heating environment). Pigment dispersion) was applied.
Then, the solvent was removed by leaving it to stand at room temperature for 1 hour, and a coating film having an average film thickness of 30 μm was obtained.
The conditions for forming the coating film were the same for each evaluation sheet.

3-1. Film thickness uniformity For the evaluation sheets of the above Examples and Comparative Examples, the thickness of the coating film was determined at 120 points at regular intervals, and the standard deviation (σ) was determined from the determined values. Evaluation was carried out according to five criteria. It can be said that the smaller the standard deviation (σ), the better the film thickness uniformity.
A: Standard deviation (σ) is less than 1.0 μm.
B: Standard deviation (σ) is 1.0 μm or more and less than 1.5 μm.
C: Standard deviation (σ) is 1.5 μm or more and less than 2.0 μm.
D: Standard deviation (σ) is 2.0 μm or more and less than 3.0 μm.
E: Standard deviation (σ) is 3.0 μm or more.

3-2. Occurrence of color unevenness and density unevenness For the evaluation sheets of the respective examples and comparative examples, visual observation is performed, and the occurrence of color unevenness and density unevenness in each part is evaluated according to the following five-stage criteria. did.
A: Color unevenness and density unevenness are not recognized at all.
B: Color unevenness and density unevenness are hardly recognized.
C: Color unevenness and density unevenness are slightly recognized.
D: Color unevenness and density unevenness are clearly recognized.
E: Color unevenness and density unevenness are remarkably recognized.

3-3. Evaluation of Lightness For the evaluation sheets of the respective Examples and Comparative Examples, tristimulus values were obtained by xyY colorimetry using a chromaticity meter (CM-3700d, manufactured by Minolta). The red coating film, the green coating film, and the blue coating film were evaluated according to the following five-stage criteria.
(Evaluation criteria for red paint film)
A: Brightness Y is 20.5 or more.
B: Lightness Y is 20.0 or more and less than 20.5.
C: Brightness Y is 19.8 or more and less than 20.0.
D: Lightness Y is 19.0 or more and less than 19.8.
E: Lightness Y is less than 19.0.

(Evaluation criteria for green paint film)
A: Brightness Y is 62.0 or more.
B: Lightness Y is 61.0 or more and less than 62.0.
C: Brightness Y is 59.5 or more and less than 61.0.
D: Brightness Y is 58.0 or more and less than 59.5.
E: Lightness Y is less than 58.0.

(Evaluation criteria for blue paint film)
A: Brightness Y is 7.2 or more.
B: Lightness Y is 7.1 or more and less than 7.2.
C: Brightness Y is 7.0 or more and less than 7.1.
D: The brightness Y is 6.8 or more and less than 7.0.
E: Lightness Y is less than 6.8.
These results are shown in Table 3. In the table, an evaluation sheet prepared using a pigment dispersion immediately after production is indicated as “before heating”, and a pigment dispersion left in a 40 ° C. environment for 7 days (a pigment dispersion left in a heated environment). The sheet for evaluation produced using “) was indicated as“ after heating ”.

  As is apparent from Table 3, in the present invention, the pigment dispersion is excellent in stability over time, has excellent film thickness uniformity even after being left under heating, and has no color unevenness and density unevenness. Was successfully formed. On the other hand, in each comparative example, a satisfactory result was not obtained.

Claims (10)

A pre-dispersing step of obtaining a dispersant dispersion in which the dispersant is dispersed in the solvent by stirring a mixture containing the dispersant, the dispersion resin, and the solvent;
A method for producing a pigment dispersion, comprising: a fine dispersion step of adding a pigment to the dispersant dispersion and adding inorganic beads in multiple stages to perform fine dispersion treatment.   The fine dispersion treatment is performed in multiple stages by performing a primary fine dispersion treatment using first inorganic beads having a predetermined particle diameter and then adding second inorganic beads having a smaller particle diameter than the first inorganic beads. The method for producing a pigment dispersion according to claim 1.   The pigment dispersion according to claim 2, wherein an average particle diameter of the first inorganic beads is 0.5 to 2.0 mm, and an average particle diameter of the second inorganic beads is 0.03 to 0.30 mm. Manufacturing method.   The method for producing a pigment dispersion according to claim 2 or 3, wherein the fine dispersion treatment is performed in two stages of a treatment using the first inorganic beads and a treatment using the second inorganic beads.   The method for producing a pigment dispersion according to any one of claims 1 to 4, wherein 1,3-butylene glycol diacetate and / or diethylene glycol dibutyl ether is used as the solvent.   The pigment is C.I. I. Pigment red 177, C.I. I. Pigment red 177 and derivatives thereof, C.I. I. Pigment red 254, and C.I. I. The method for producing a pigment dispersion according to any one of claims 1 to 5, wherein the pigment red 254 and derivatives thereof are selected.   The pigment is C.I. I. Pigment green 58 or C.I. I. The method for producing a pigment dispersion according to any one of claims 1 to 5, wherein the pigment green 58 and other pigment derivatives are used.   The pigment is C.I. I. Pigment blue 15: 6 or C.I. I. Pigment blue 15: 6 and C.I. I. 6. The method for producing a pigment dispersion according to claim 1, wherein the pigment dispersion is a pigment blue 15 derivative.   A pigment dispersion produced using the method according to claim 1. The pigment content is 10 wt% or more, the viscosity at 25 ° C. is 12 mPa · s or less, and
The pigment dispersion according to claim 9, wherein the amount of change in viscosity at 25 ° C after standing for 7 days in an environment of 40 ° C is 0.5 mPa · s or less.