JP2022014584A - Production method of pigment composition - Google Patents

Abstract

To provide a production method of a pigment composition that can reduce the number of coarse particles that may be contained in a pigment composition and prevent degradation of storage stability caused by time-dependent increase of the number of coarse particles while improving production efficiency of the pigment composition.SOLUTION: A production method of a pigment composition is characterized by including a step C for processing a first raw material composition in a rotor-stator type processing machine or the like to produce a second raw material composition and for processing the second raw material composition in a dispersing machine having a mechanism or the like to collide the second raw material composition with each other. The liquid medium contains a liquid medium (a) having a dispersal term (δD1) of 16-19, a polarity term (δP1) of 8-13, and a hydrogen bond term (δH1) of 9-30.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for producing a pigment composition.

The pigment composition is used in various printing such as inkjet printing. As a method for producing a pigment composition, a method for obtaining a pigment composition by treating a raw material composition containing a pigment component and a liquid medium with a disperser is known (see, for example, Patent Document 1 below).

Japanese Unexamined Patent Publication No. 2001-262038

The pigment composition is required to have a small number of coarse particles from the viewpoint of suppressing clogging of the ejection nozzle during printing and obtaining good ejection stability.

In order to reduce the number of coarse particles, it is effective to disperse a raw material composition containing a resin component such as a pigment or a pigment dispersion resin and a liquid medium for a long period of time, or to repeatedly put it into a disperser for treatment. ..

However, the above method may not be able to improve the production efficiency of pigment compositions, inks, and the like.

The problem to be solved by the present invention is that the number of coarse particles that can be contained in the pigment composition can be reduced, the deterioration of storage stability due to the increase in the number of coarse particles over time can be prevented, and the production efficiency of the pigment composition can be prevented. It is an object of the present invention to provide a method for producing a pigment composition that can achieve both improvement and improvement.

The present invention is a step A for producing a first raw material composition by mixing a resin component, a pigment component, a basic compound, and a liquid medium, and a rotor stator type processing machine for the first raw material composition. Alternatively, step B for producing the second raw material composition by processing with a bead mill processing machine, an ultrasonic disperser, or a disper, and the second raw material composition can be combined with each other. The pigment component is dispersed in a liquid medium by the resin component, which comprises step C of treating the second raw material composition with a disperser having a structure for colliding with the hard body. In the method for producing a pigment composition, the liquid medium has a dispersion term (δD ¹ ) in the range of 15 to 20, a polar term (δP ¹ ) in the range of 8 to 15, and a range of 8 to 30. The present invention relates to a method for producing a pigment composition, which comprises a liquid medium (a) having a hydrogen bonding term (δH ¹ ).

According to the method for producing a pigment composition of the present invention, the number of coarse particles having a particle size of 1.0 μm or more that can be contained in the pigment composition can be reduced, and the storage stability is lowered due to an increase in the number of coarse particles over time. Can be prevented, and the production efficiency of the pigment composition can be improved at the same time.

It is a schematic sectional drawing which shows an example of the rotor stator type processing machine. It is a schematic side view which shows the example of the stator in the rotor stator type processing machine. It is a schematic diagram for demonstrating the crushing process or the crushing process in a rotor stator type processing machine.

Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be variously modified and implemented within the scope of the gist thereof.

In the present specification, the numerical range indicated by using "-" indicates a range including the numerical values before and after "-" as the minimum value and the maximum value, respectively. Within the numerical range described stepwise herein, the upper or lower limit of the numerical range at one stage may be optionally combined with the upper or lower limit of the numerical range at another stage. In the numerical range described in the present specification, the upper limit value or the lower limit value of the numerical range may be replaced with the value shown in the examples. "A or B" may include either A or B, and may include both. Unless otherwise specified, the materials exemplified in the present specification may be used alone or in combination of two or more. The content of each component in the composition means the total amount of the plurality of substances present in the composition when a plurality of substances corresponding to each component are present in the composition, unless otherwise specified. The term "process" is included in this term not only in an independent process but also in the case where the intended action of the process is achieved even if it cannot be clearly distinguished from other processes. "(Meta) acrylic acid" is a general term for acrylic acid and methacrylic acid corresponding thereto, and is the same in other similar expressions such as "(meth) acrylate".

The method for producing a pigment composition of the present invention comprises a step A of producing a first raw material composition by mixing a resin component, a pigment component, a basic compound, and a liquid medium, and the first raw material composition. Step B for producing a second raw material composition by treating a substance with a rotor stator type processing machine, a bead mill processing machine, an ultrasonic disperser, or a disper, and the second raw material composition for the second raw material composition. The pigment component is liquid due to the resin component, which comprises a step C of processing with a disperser having a structure in which the raw material compositions collide with each other or a structure in which the second raw material composition collides with a hard body. A method for producing a pigment composition dispersed in a medium, wherein the liquid medium has a dispersion term (δD ¹ ) in the range of 15 to 20, a polar term (δP ¹ ) in the range of 8 to 15, and 8. It is characterized by containing a liquid medium (a) having a hydrogen bonding term (δH ¹ ) in the range of about 30.

The pigment composition obtained by the above method refers to a pigment component dispersed in a liquid medium such as water (specifically, an aqueous pigment dispersion) by a resin component such as the pigment dispersion resin. The pigment composition may be used as a material for producing an ink, or the pigment composition itself may be used as an ink. The pigment composition is preferably used, for example, for producing a printing ink or the printing ink, and more preferably used for producing an inkjet printing ink or an inkjet printing ink.

When the pigment composition is used for producing the ink for inkjet printing, the ratio of the solid content of the pigment composition to the total amount of the pigment composition is preferably in the range of 1% by mass to 60% by mass. It is more preferably in the range of 10% by mass to 30% by mass.

First, step A of the present invention will be described.

Step A is a step of producing a first raw material composition by mixing a resin component, a pigment component, a basic compound, and a liquid medium.

In the step A, a liquid medium containing a liquid medium (a) having a dispersion term (δD ¹ ), a polarity term (δP ¹ ), and a hydrogen bond term (δH ¹ ) within the following ranges is used. ..

The dispersion term (δD ¹ ) of the liquid medium (a) is preferably in the range of 12 to 24, more preferably 14 to 21, and particularly preferably 16 to 19.

The polarity term (δP ¹ ) of the liquid medium (a) is preferably in the range of 4 to 17, more preferably 6 to 15, and particularly preferably 8 to 13.

The hydrogen bond term (δH ¹ ) of the liquid medium (a) is preferably in the range of 6 to 43, more preferably 9 to 35, and particularly preferably 9 to 30.

Examples of the liquid medium having a dispersion term (δD ¹ ), a polar term (δP ¹ ), and a hydrogen bond term (δH ¹ ) within the above range include triethylene glycol, glycerin, 2-pyrrolidone, and 1- (2- (2-). Hydroxyethyl) -2-pyrrolidone, dipropylene glycol, propylene glycol, 1,5-pentanediol and the like can be used alone or in combination of two or more.

As the liquid medium (a), a pigment composition having a viewpoint that the number of coarse particles can be easily reduced efficiently and having desired physical characteristics of solid content (number of coarse particles, particle size, etc.) can be obtained through the step C. From the viewpoint of easily shortening the time required, it is preferable to satisfy at least one of the following.

When the pigment component contains carbon black, the liquid medium (a) preferably contains at least one selected from the group consisting of N- (2-hydroxyethyl) pyrrolidone, 2-pyrrolidone, triethylene glycol and glycerin.

When the pigment component contains a magenta pigment, the liquid medium (a) preferably contains at least one selected from the group consisting of 2-pyrrolidone, triethylene glycol, dipropylene glycol and glycerin.

When the pigment component contains a cyan pigment, the liquid medium (a) contains at least one selected from the group consisting of dipropylene glycol, N- (2-hydroxyethyl) pyrrolidone, 2-pyrrolidone, triethylene glycol and glycerin. Is preferable.

When the pigment component contains a yellow pigment, the liquid medium (a) contains at least one selected from the group consisting of propylene glycol, N- (2-hydroxyethyl) pyrrolidone, 2-pyrrolidone, triethylene glycol and glycerin. Is preferable.

The values of the dispersion term (δD ¹ ), the polarity term (δP ¹ ), and the hydrogen bond term (δH ¹ ) of the liquid medium are the computer software Hansen Solubility Parameters in Practice 4th Edition 4.1.07 (HSPiP). It is a value recorded in.

By using a liquid medium containing a liquid medium (a) having a dispersion term (δD ¹ ), a polar term (δP ¹ ), and a hydrogen bond term (δH ¹ ) within the above range, the pigment component can be wetted. Promotes swelling and dissolution of resin components. As a result, it is possible to obtain an ink having further excellent storage stability and easily suppressing clogging of the ink ejection nozzle at the initial stage of ink ejection, and a pigment composition used for the production thereof.

The liquid medium (a) is preferably used in the range of 10 to 90% by mass, preferably in the range of 15 to 80% by mass, based on the total amount of the liquid medium contained in the pigment composition. The components and resin components are easily wetted, swollen or dissolved in the liquid medium, the adsorption of the pigment components on the surface is promoted, and it is easy to maintain a good dispersed resin. As a result, it is easy to obtain excellent storage stability that prevents the occurrence of solid content over time in the pigment composition, it is easy to prevent the occurrence of solid content over time in the ink, and the ink is ejected at the initial stage of ink ejection. It is easy to suppress the clogging of the nozzles (easy to obtain excellent initial ejection stability), and it is easy to suppress the clogging of the ink ejection nozzles over time (excellent ejection stability over time). Cheap).

As the liquid medium, the liquid medium (a) and the liquid medium (b) other than the liquid medium (a) can be used in combination, so that the resin component such as the pigment dispersion resin is adsorbed on the surface of the pigment component. It is preferable because it becomes easy. In particular, when a high-pressure homogenizer is used in producing the pigment composition of the present invention, or when the inkjet printing ink obtained by using the pigment composition is applied to a thermal type inkjet printing method described later. , The liquid medium (a) and the liquid medium (b) described later are preferably used in combination.

Examples of the liquid medium (b) include an aqueous medium (water and the like), an organic solvent and the like. When a high-pressure homogenizer is used as the disperser used in the present invention, it is preferable to use a water-soluble organic solvent among the above organic solvents because a high pressure is applied, and it is preferable to use a high boiling point solvent having a boiling point of 100 ° C. or higher. More preferred.

Examples of water include ion-exchanged water, ultra-filtered water, reverse osmosis water, distilled water and other ion-exchanged water; ultrapure water and the like. As the water, it is preferable to use water sterilized by irradiation with ultraviolet rays, addition of hydrogen peroxide, or the like from the viewpoint of easily preventing the growth of mold or bacteria when the pigment composition or ink is stored for a long period of time.

The water is preferably used in the range of 10 to 90% by mass, and the water-based ink is preferably used in the range of 15 to 80% by mass with respect to the total amount of the liquid medium contained in the pigment composition of the present invention. It is preferable in manufacturing.

As the organic solvent, a water-soluble organic solvent can be used. The water-soluble organic solvent easily wets the surface of the pigment component efficiently, and the resin component dissolved in water (for example, a resin neutralized product) is easily adsorbed on the pigment component, shortening the time required to reach the desired physical properties. It's easy to do.

Examples of the water-soluble organic solvent include glycols such as ethylene glycol, diethylene glycol, tetraethylene glycol, tripropylene glycol, polyethylene glycol and polypropylene glycol; diols such as butanediol, pentanediol and hexanediol; glycols such as propylene glycol laurate. Esters; Diethylene glycol ethers such as diethylene glycol monoethyl, diethylene glycol monobutyl, diethylene glycol monohexyl, carbitol; glycol ethers such as cellosolve containing propylene glycol ether, dipropylene glycol ether or triethylene glycol ether; methanol, ethanol, isopropyl alcohol , 1-propanol, 2-propanol, 1-butanol, 2-butanol, butyl alcohol, pentyl alcohol and other alcohols (excluding glycols); sulfolanes, esters, ketones, γ-butyrolactone and other lactones; N- ( Examples thereof include lactams such as 2-hydroxyethyl) pyrrolidone and 2-pyrrolidone. The water-soluble organic solvent can be used alone or in combination of two or more.

The water-soluble organic solvent has a boiling point of triethylene glycol, glycerin, 2-pyrrolidone, 1- (2-hydroxyethyl) -2-pyrrolidone, dipropylene glycol, propylene glycol, 1,5-pentanediol and the like. It is preferable to use a high boiling point solvent having a temperature of 100 ° C. or higher in order to promote the wetting of the pigment, and as a result, the resin is easily adsorbed on the pigment and the storage stability and the like are improved.

The content of the water-soluble organic solvent is preferably 10 to 500 parts by mass, more preferably 15 to 200 parts by mass, and 15 to 150 parts by mass with respect to 100 parts by mass of the pigment component contained in the first raw material composition. Is more preferable. In these cases, it is easy to obtain excellent storage stability that prevents the occurrence of solid content over time in the pigment composition, it is easy to prevent the occurrence of solid content over time in the ink, and the ink at the initial stage of ink ejection. It is easy to suppress the clogging of the ejection nozzle (it is easy to obtain excellent initial ejection stability), and it is easy to suppress the clogging of the ink ejection nozzle over time (excellent ejection stability over time). Easy to get).

The liquid medium contained in the pigment composition is preferably used in the range of 40 to 95% by mass, preferably in the range of 60 to 90% by mass, based on the total amount of the pigment composition of the present invention. It is preferable for producing ink.

Moreover, as a resin component used in the said step A, a pigment dispersion resin, a binder resin and the like can be mentioned.

As the resin component, a conventionally known resin can be used, but for example, a radical polymer can be used, and it is preferable to use a radical polymer having an aromatic ring structure or a heterocyclic structure. In this case, the π-π interaction between the resin component such as the pigment-dispersed resin and the pigment component facilitates the adsorption of the resin component such as the pigment-dispersed resin to the pigment component, and the solid content in the pigment composition precipitates over time. It is easy to obtain excellent storage stability to prevent the occurrence of ink, it is easy to prevent the occurrence of sedimentation of solids in the ink over time, and it is easy to suppress the occurrence of clogging of the ink ejection nozzle at the initial stage of ink ejection (excellent). It is easy to obtain initial ejection stability), and it is easy to suppress the occurrence of clogging of the ink ejection nozzle over time (it is easy to obtain excellent ink ejection stability over time).

Examples of the aromatic ring structure or the heterocyclic structure include a ring structure introduced into the radical polymer by using a monomer having an aromatic ring structure or a heterocyclic structure. The aromatic ring structure is preferably a benzene ring structure, more preferably a styrene-derived structure. By using a resin component which is a radical polymer having an aromatic ring structure or a heterocyclic structure, the adsorptivity of the resin component such as a pigment dispersion resin to the pigment component can be enhanced, and the solid in the pigment composition. It is easy to obtain excellent storage stability to prevent the occurrence of sedimentation over time, it is easy to prevent the occurrence of sedimentation of solids in ink over time, and it causes clogging of the ink ejection nozzle at the initial stage of ink ejection. (It is easy to obtain excellent initial ejection stability), and it is easy to suppress the occurrence of clogging of the ink ejection nozzle over time (it is easy to obtain excellent ink ejection stability over time).

As the radical polymer that can be used as a resin component such as a pigment dispersion resin, for example, a polymer obtained by radical polymerization of various monomers can be used.

As the monomer, if an aromatic cyclic structure is introduced into a resin component such as a pigment dispersion resin, a monomer having an aromatic cyclic structure can be used, and a heterocyclic structure is introduced. If so, a monomer having a heterocyclic structure can be used.

Examples of the monomer having an aromatic ring structure include styrene, p-tert-butyldimethylsiloxystyrene, o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, p-tert-butoxystyrene, and m-. tert-butoxystyrene, p-tert- (1-ethoxymethyl) styrene, m-chlorostyrene, p-chlorostyrene, p-fluorostyrene, α-methylstyrene, p-methyl-α-methylstyrene, vinylnaphthalene, vinyl Anthracen and the like can be mentioned.

Examples of the monomer having a heterocyclic structure include vinylpyridine monomers such as 2-vinylpyridine and 4-vinylpyridine.

When a polymer having both an aromatic cyclic structure and a heterocyclic structure is used as the radical polymer, the monomer has a monomer having an aromatic cyclic structure and a heterocyclic structure. It can be used in combination with monomers.

As the resin component of the pigment dispersion resin or the like, a radical polymer having an aromatic cyclic structure is preferable. Therefore, as the monomer, a monomer having an aromatic cyclic structure is preferable, and at least one selected from the group consisting of styrene, α-methylstyrene and tert-butylstyrene is more preferable.

The content of the monomer having an aromatic ring structure or a heterocyclic structure is based on the total amount of the monomer from the viewpoint of further enhancing the adsorptivity of the resin component such as the pigment dispersion resin to the pigment component. 20% by mass or more is preferable, 40% by mass or more is more preferable, and 50 to 95% by mass is further preferable.

As the resin component of the pigment dispersion resin or the like, a monomer having an acid group can be used as the monomer from the viewpoint of producing a radical polymer having an acid value in the range described later.

Examples of the monomer having an acid group include a monomer having a carboxy group, a sulfo group, a phosphoric acid group and the like. As the monomer having an acid group, a monomer having a carboxy group is preferable, and at least one selected from the group consisting of acrylic acid and methacrylic acid is more preferable. In these cases, it is easy to obtain excellent storage stability that prevents the occurrence of solid content over time in the pigment composition, it is easy to prevent the occurrence of solid content over time in the ink, and the ink at the initial stage of ink ejection. It is easy to suppress the clogging of the ejection nozzle (it is easy to obtain excellent initial ejection stability), and it is easy to suppress the clogging of the ink ejection nozzle over time (excellent ejection stability over time). Easy to get).

The content of the monomer having an acid group is 5 to 80 mass based on the total amount of the monomers that can be used for producing the resin component from the viewpoint of easily obtaining a radical polymer having an acid value in the range described later. % Is preferable, 5 to 60% by mass is more preferable, and 5 to 50% by mass is further preferable.

As the monomer that can be used for producing a resin component such as a pigment-dispersed resin, other monomers can be used, if necessary, in addition to the above-mentioned monomers. Examples of other monomers include methyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, sec-butyl (meth) acrylate, and tert-butyl ( Meta) acrylate, 2-ethylbutyl (meth) acrylate, 1,3-dimethylbutyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, ethyl (meth) acrylate, n -Butyl (meth) acrylate, 2-methylbutyl (meth) acrylate, pentyl (meth) acrylate, heptyl (meth) acrylate, nonyl (meth) acrylate, 3-ethoxypropyl (meth) acrylate, 3-ethoxybutyl (meth) acrylate , Dimethylaminoethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, ethyl-α- (hydroxymethyl) (meth) acrylate, dimethylaminoethyl (meth) acrylate, hydroxyethyl (Meta) acrylate, hydroxypropyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, phenylethyl (meth) acrylate, diethylene glycol (meth) acrylate, triethylene glycol (meth) acrylate, polyethylene glycol (meth) Examples thereof include acrylate, glycerin (meth) acrylate, bisphenol A (meth) acrylate, dimethyl maleate, diethyl maleate, vinyl acetate and the like. These monomers can be used alone or in combination of two or more. As the other monomer, such an acrylate or a methacrylate may be used alone, or a combination of the acrylate and the methacrylate may be used.

As resin components such as pigment dispersion resin, a polymer having a linear structure formed by radical polymerization of a monomer, a polymer having a branched (grafted) structure, and a polymer having a crosslinked structure. Etc. can be used. The monomer sequence is not particularly limited in each polymer, and a polymer having a random type sequence or a block type sequence can be used.

A polymer having a crosslinked structure can be produced by using a monomer having a crosslinkable functional group as a monomer. Examples of the monomer having a crosslinkable functional group include ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, poly (oxyethylene oxypropylene) glycol di (meth) acrylate, and the like. Poly (meth) acrylates of polyhydric alcohols such as tri (meth) acrylates of glycerin alkylene oxide adducts; glycidyl (meth) acrylates; divinylbenzene and the like.

As the resin component of the pigment dispersion resin or the like, a polymer having a structural unit derived from the above-mentioned monomer can be used, but a monomer having an anionic group and an aromatic ring structure or a heterocyclic structure can be used. A polymer obtained by polymerizing only the monomer having the same is preferable.

As the resin component of the pigment dispersion resin or the like, a polymer having a structural unit derived from styrene and a structural unit derived from (meth) acrylic acid is preferable, and a styrene- (meth) acrylic acid copolymer and styrene- (meth)-(meth). ) Acrylic acid-based ester-At least one selected from the group consisting of (meth) acrylic acid copolymer is more preferable. A polymer having a structural unit derived from styrene and a structural unit derived from (meth) acrylic acid preferably has an acid value in the range described below. The aromatic ring moiety in the structural unit derived from styrene is strongly adsorbed on the surface of the pigment component, and the carboxy group in the structural unit derived from (meth) acrylic acid has a good affinity with water for good dispersion stabilization. Is easy to obtain. As a result, it is easy to obtain excellent storage stability that prevents the occurrence of solid content over time in the pigment composition, it is easy to prevent the occurrence of solid content over time in the ink, and the ink is ejected at the initial stage of ink ejection. It is easy to suppress the clogging of the nozzles (easy to obtain excellent initial ejection stability), and it is easy to suppress the clogging of the ink ejection nozzles over time (excellent ejection stability over time). Cheap).

As the styrene- (meth) acrylic acid copolymer, any of a styrene-acrylic acid copolymer, a styrene-methacrylic acid copolymer, and a styrene-acrylic acid-methacrylic acid copolymer can be used, but styrene-. At least one selected from the group consisting of the acrylic acid copolymer and the styrene-acrylic acid-methacrylic acid copolymer is preferable. In this case, it is easy to adjust the adsorption force with the pigment component and the dispersion force in water, and as a result, it is easy to obtain excellent storage stability that prevents the occurrence of sedimentation of solids in the pigment composition over time. It is easy to prevent the occurrence of sedimentation of solids in the ink over time, it is easy to suppress clogging of the ink ejection nozzle at the initial stage of ink ejection (it is easy to obtain excellent initial ejection stability), and ink over time. It is easy to suppress the clogging of the discharge nozzle (it is easy to obtain excellent discharge stability over time).

In the styrene- (meth) acrylic acid copolymer, the total amount of the structural unit derived from styrene, the structural unit derived from acrylic acid and the structural unit derived from methacrylic acid is the structural unit of the styrene- (meth) acrylic acid copolymer. Based on the total amount, 80 to 100% by mass is preferable, and 90 to 100% by mass is more preferable.

The radical polymerization rate (reaction rate) of each monomer during radical polymerization is almost the same, and the usage ratio (charge ratio) of each monomer is a structural unit derived from each monomer constituting the radical polymer. Is considered to be the same as the ratio of.

The radical polymer can be produced, for example, by radically polymerizing the above-mentioned monomer by a method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, or an emulsion polymerization method.

When producing a radical polymer, a known and commonly used polymerization initiator, chain transfer agent (polymerization degree adjusting agent), surfactant, defoaming agent and the like can be used, if necessary.

Examples of the polymerization initiator include 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, and 1,1'-azobis (cyclohexane-1-carbonitrile). , Benzoyl peroxide, dibutyl peroxide, butyl peroxybenzoate and the like. The content of the polymerization initiator is preferably 0.1 to 10% by mass based on the total amount of the monomers used in the production of the radical polymer.

When the radical polymer obtained by the solution polymerization method is used, as the resin component such as the pigment dispersion resin, the solvent contained in the radical polymer solution obtained by the solution polymerization method is removed, and then dried and pulverized. A finely divided radical polymer can be used. When the resin component, which is a finely divided radical polymer, is used in combination with a water-soluble organic solvent and a basic compound, it is neutralized by the basic compound in the 0th step, and is a liquid medium containing the water-soluble organic solvent. The pigment component that is dissolved in the liquid medium and wet with the liquid medium is adsorbed on the surface. As a result, it is easy to obtain excellent storage stability that prevents the occurrence of solid content over time in the pigment composition, it is easy to prevent the occurrence of solid content over time in the ink, and the ink is ejected at the initial stage of ink ejection. It is easy to suppress the clogging of the nozzles (easy to obtain excellent initial ejection stability), and it is easy to suppress the clogging of the ink ejection nozzles over time (excellent ejection stability over time). Cheap).

As the resin component of the pigment-dispersed resin or the like, a resin component classified by a mesh-like sieve having an eye size (diameter) of 1 mm or less is preferable.

The acid value of the resin component such as the pigment dispersion resin is preferably 60 to 300 mgKOH / g, more preferably 80 to 250 mgKOH / g, further preferably 100 to 200 mgKOH / g, and particularly preferably 120 to 180 mgKOH / g. In these cases, the adsorptivity of the resin component such as the pigment dispersion resin to the pigment component can be enhanced, and it is easy to obtain an appropriate affinity for a liquid medium (for example, a liquid medium containing water and a water-soluble organic solvent). Therefore, it is easy to maintain a good dispersed state. Therefore, it is easy to obtain excellent storage stability for preventing the generation of solid content over time in the pigment composition, it is easy to prevent the occurrence of solid content over time in the ink, and the ink ejection nozzle at the initial stage of ink ejection. It is easy to suppress the occurrence of clogging, etc. (easy to obtain excellent initial ejection stability), and it is easy to suppress the occurrence of clogging of the ink ejection nozzle over time (easy to obtain excellent ink ejection stability over time). ).

The acid value is preferably an acid value derived from an anionic group such as a carboxy group, a sulfo group or a phosphoric acid group. The acid value is a test of acid value, saponification value, ester value, iodine value, hydroxyl value and unsaponifiable matter of Japanese Industrial Standards "K0070: 1992. Except for using tetrahydrofuran instead of diethyl ether as a solvent. It is a numerical value measured according to "Method" and refers to the amount (mg) of potassium hydroxide required to completely neutralize 1 g of a resin component such as a pigment-dispersed resin.

The weight average molecular weight of the resin component such as the pigment dispersion resin is preferably 2000 to 40,000, more preferably 5000 to 30000, further preferably 5000 to 25000, and particularly preferably 8000 to 12000. In these cases, aggregation with neighboring pigment components is suppressed, excellent storage stability that prevents the occurrence of sedimentation of solids over time in the pigment composition can be easily obtained, and sedimentation of solids over time in the ink can be easily obtained. It is easy to prevent the occurrence, it is easy to suppress the clogging of the ink ejection nozzle at the initial stage of ink ejection (it is easy to obtain excellent initial ejection stability), and it is easy to cause the clogging of the ink ejection nozzle over time. Easy to suppress (easy to obtain excellent aging stability). The "weight average molecular weight" is a value measured by a GPC (gel permeation chromatography) method and is a value converted into a molecular weight of polystyrene used as a standard substance.

As the resin component used in the step A, it is preferable to use a resin component having a neutralization rate of 0 to 10% by mass. That is, as the resin component, it is preferable to use one in which all or most of the acid groups of the resin component are not neutralized by the basic compound. As the resin component, those having a neutralization rate of 0 to 10% by mass are preferably used, those having a neutralization rate of 0 to 5% by mass are more preferable, and those having a neutralization rate of 0 to 0.1% by mass are used. It is preferable to use 0% by mass because the shearing force to the raw material composition is improved, the resin component is easily adsorbed to the pigment component, and the storage stability of the pigment composition is improved.

Here, the neutralization rate refers to a value calculated by the following formula.

Neutralization rate [%] = ((mass of basic compound [g] × 56 × 1000) / (acid value of resin component × equivalent of basic compound × (mass of resin component [g])) × 100

On the other hand, the acid group of the resin component contained in the first raw material composition obtained through the step A is neutralized by the basic compound in the step A. The neutralization rate of the resin component contained in the first raw material composition is preferably in the range of 50 to 100% by mass, preferably in the range of 80 to 100% by mass, and preferably in the range of 90 to 100% by mass. Is preferable.

When the neutralization rate of the pigment-dispersed resin contained in the first raw material composition obtained through the step A is within the above range, the resin component is easily dissolved or dispersed in a liquid medium containing water, and the pigment component is easily dissolved. Is promoted to be adsorbed on the surface, and it is easy to maintain a good dispersed state. As a result, it is easy to obtain excellent storage stability that prevents the occurrence of solid content over time in the pigment composition, it is easy to prevent the occurrence of solid content over time in the ink, and the ink is ejected at the initial stage of ink ejection. It is easy to suppress the clogging of the nozzles (easy to obtain excellent initial ejection stability), and it is easy to suppress the clogging of the ink ejection nozzles over time (excellent ejection stability over time). Cheap).

The content of the resin component such as the pigment dispersion resin is preferably 5 to 200 parts by mass, more preferably 10 to 100 parts by mass with respect to 100 parts by mass of the pigment component contained in the first raw material composition. As a result, it is easy to maintain a good dispersed state due to sufficient affinity for a liquid medium (for example, water), and a resin component such as a pigment-dispersed resin is easily adsorbed on the pigment component. It is easy to obtain excellent storage stability to prevent the occurrence of sedimentation, it is easy to prevent the occurrence of solid content over time in the ink, and it is easy to suppress the clogging of the ink ejection nozzle at the initial stage of ink ejection. (It is easy to obtain excellent initial ejection stability), and it is easy to suppress the occurrence of clogging of the ink ejection nozzle over time (it is easy to obtain excellent ink ejection stability over time). Further, the amount of the resin component such as the free pigment dispersion resin that is not adsorbed on the pigment component is reduced, and the ink ejection property is likely to be improved. Further, it is easy to suppress the aggregation of the pigment component due to the resin component such as the free pigment dispersion resin, and it is easy to stabilize the ink.

Next, the basic compound used in the step A will be described.

The basic compound can be used to neutralize the acid group of the resin component such as the pigment dispersion resin.

As the basic compound, an inorganic basic compound, an organic basic compound, or the like can be used. Examples of the inorganic basic compound include alkali metal hydroxides such as potassium and sodium; alkali metal carbonates such as potassium and sodium; alkaline earth metal hydroxides such as calcium and barium; calcium, barium and the like. Examples include carbonates. Examples of the organic basic compound include amino alcohols such as triethanolamine, N, N-dimethanolamine, N-ethylethanolamine, dimethylethanolamine and N-butyldiethanolamine; morpholine, N-methylmorpholine and N-ethyl. Morpholines such as morpholine; piperazine such as N- (2-hydroxyethyl) piperazine, piperazine hexahydrate; ammonium hydroxide and the like can be mentioned. Since the basic compound is excellent in neutralizing efficiency of the resin component such as the pigment dispersion resin, the dispersion stability of the pigment component adsorbed by the resin component such as the pigment dispersion resin in a liquid medium such as water can be easily improved. , Alkali metal hydroxides (potassium hydroxide, sodium hydroxide, lithium hydroxide, etc.) are preferable, and potassium hydroxide is more preferable.

When the basic compound is used in the step A, it is preferably used in a form previously dissolved or dispersed in water.

As the basic compound, it is preferable to use an amount in which the neutralization rate of the resin component contained in the first raw material composition is in the range of 50 to 100% by mass, and the amount is in the range of 80 to 100% by mass. Is preferable, and it is particularly preferable to use an amount in the range of 90 to 100% by mass in order to improve the solubility of the resin component in the liquid medium.

Next, the pigment component used in the step A will be described.

As the pigment component, at least one selected from the group consisting of pigments and pigment derivatives can be used.

As the pigment, an inorganic pigment or an organic pigment can be used. Examples of the inorganic pigment include iron oxide, carbon black (for example, carbon black produced by a known method such as a contact method, a furnace method, a thermal method), titanium oxide and the like. Examples of organic pigments include azo pigments (insoluble azo pigments (monoazo pigments, disazo pigments, pyrazolone pigments, etc.), benzimidazolone pigments, beta naphthol pigments, naphthol AS pigments, condensed azo pigments, etc.), polycyclic pigments (quinacridone pigments, etc.). Perylene pigments, perinone pigments, anthraquinone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, isoindrin pigments, quinophthalone pigments, diketopyrrolopyrrole pigments, etc.), phthalocyanine pigments, dye chelate (basic dye type chelate, acid dye type) Chelate etc.), nitro pigments, nitroso pigments, aniline blacks and the like. These inorganic pigments and organic pigments can be suitably used for producing printing inks (for example, ink jet printing inks). As the pigment, one kind alone or two or more kinds can be used in combination.

As carbon black, # 2300, # 980, # 960, # 900, # 52, # 45L, # 45, # 40, # 33, MA100, MA8, MA7, etc. manufactured by Mitsubishi Chemical Corporation; Regal manufactured by Cabot Corporation. Series, Monarch series, etc .; Color Black FW1, Color Black series, Printex series, Special Black series, NIPEX series, etc. manufactured by Orion Engineered Carbons Co., Ltd. can be used.

As the pigment, C.I. I. Pigment Yellow 1, 2, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 120, 128, 129, 138, 150, 151, Yellow pigments such as 154, 155, 174, 180 and 185 can be used.

As the pigment, C.I. I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 122, 123, 146, 149, 150, 168, 176, 184, 185, 202, 209 Magenta pigments such as 213, 269, and 282 can be used.

As the pigment, C.I. I. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 22, 60, 63, 66 and the like can be used.

As the pigment, C.I. I. Pigment oranges 5, 13, 16, 17, 34, 36, 43, 51, 64, 71 and the like can be used.

As the pigment, C.I. I. Pigment Violet 1, 3, 5: 1, 16, 19, 23, 38 and other violet pigments can be used.

As the pigment, C.I. I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, 50, 58 and other green pigments can be used.

As the pigment, a dry pigment (pigment in the state of dry powder) or a wet pigment (pigment in the state of a wet cake) can be used. As the magenta pigment, the time for obtaining a pigment composition having desired physical properties (number of coarse particles, particle size, etc.) of solid content through the step C is shortened from the viewpoint of easily reducing the number of coarse particles efficiently. Wet pigments are preferable from the viewpoint of easy conversion. As the cyan pigment, the time required for obtaining a pigment composition having desired physical properties (number of coarse particles, particle size, etc.) of solid content through the step C is shortened from the viewpoint of easily reducing the number of coarse particles efficiently. Dry pigments are preferable from the viewpoint of easy conversion. As the pigment, a mixture containing two or more kinds or a solid solution can also be used.

As the pigment component, a pigment derivative can be used in combination with the above-mentioned pigment.

As the pigment derivative, a compound in which a functional group is introduced into the pigment can be used. Examples of the pigment that gives the pigment derivative include phthalocyanine pigments, azo pigments, anthraquinone pigments, quinacridone pigments, diketopyrrolopyrrole pigments and the like. Examples of the functional group include a carboxy group, a sulfo group, an amino group, a nitro group, an acid amide group, a carbonyl group, a carbamoyl group, a phthalimide group, a sulfonyl group and the like. The pigment derivative can impart dispersion stability to the pigment composition or ink, which enables prevention of generation of coarse particles over time and prevention of precipitation of pigment components and the like over time.

The primary particle size of the pigment component is preferably 1.0 μm or less, more preferably 0.01 to 0.5 μm, from the viewpoint of more effectively suppressing the sedimentation of the pigment component over time. The primary particle size refers to the value of the number average particle size measured using a transmission electron microscope (TEM).

The pigment component is preferably 1 to 50% by mass, more preferably 10 to 30% by mass, still more preferably 15 to 25% by mass, based on the total amount of the first raw material composition. In these cases, since it is easy to obtain appropriate fluidity, efficient and uniform treatment can be performed in each process, and excellent storage stability that prevents the occurrence of sedimentation of solids over time in the pigment composition is achieved. It is easy to obtain, it is easy to prevent the occurrence of sedimentation of solids in the ink over time, it is easy to suppress clogging of the ink ejection nozzle at the initial stage of ink ejection (it is easy to obtain excellent initial ejection stability), and it is easy to obtain it over time. It is easy to suppress the occurrence of clogging of the ink ejection nozzle (it is easy to obtain excellent ink ejection stability over time).

In the step A, the liquid medium including the liquid medium (a), the resin component, the pigment component, and the basic compound are mixed. Examples of the embodiment of the step A include the following (i) to (iii).
(I) A liquid medium containing the liquid medium (a) is mixed with a basic compound or an aqueous solution thereof to produce a mixture. A step of separately supplying a resin component such as the pigment dispersion resin and a pigment component to the mixture, or supplying and mixing a mixture of a resin component such as the pigment dispersion resin and a pigment component in advance.
(Ii) A mixture is produced by mixing a liquid medium containing the liquid medium (a) with a resin component such as the pigment dispersion resin and a pigment component. A step of mixing a basic compound or an aqueous solution thereof with the mixture.
(Iii) A liquid medium containing the liquid medium (a) and a pigment component are mixed to produce a mixture. A resin component such as the pigment dispersion resin is mixed with the mixture to produce a mixture. A step of mixing a basic compound or an aqueous solution thereof with the mixture.

In step A, a resin component such as a pigment dispersion resin having an acid group and a neutralization rate of 0 to 10% by mass is used as the resin component, and the pigment component, the basic compound, and the liquid medium are mixed with the resin component. The step of producing the first raw material composition in which the acid group of the resin component is neutralized improves the shearing force on the raw material composition, and the resin component is easily adsorbed on the pigment component, so that the pigment composition It is preferable because it improves storage stability. Therefore, it is preferable that the resin component such as the pigment dispersion resin is supplied to the container in the form of a solid (powder) rather than being supplied to the container in the form of a pre-neutralized aqueous dispersion or an aqueous solution. ..

Next, the step B will be described.

The step B is a step of producing a second raw material composition by treating the first raw material composition obtained in the step A with a processing machine described later.

The step B is a step of pulverizing or crushing the aggregated pigment. The crushing means, for example, a process of crushing an integral mass. Cracking means, for example, a process of unraveling agglomerates.

As the second raw material composition used in the step C described later, the first raw material composition previously processed in the step B can be used, and the second raw material composition can be used as a disperser in the step C many times. However, it is possible to significantly reduce the number of times of repeated charging and processing, and as a result, it is preferable in that the production efficiency of the pigment composition and the ink is remarkably improved.

On the other hand, if the raw material composition containing a large amount of coarse particles obtained without going through the steps A and B is processed by the disperser in the step C, there is a possibility that problems such as clogging of pipes may occur in the disperser. I am concerned. Therefore, from the viewpoint of avoiding such a problem, prior to the step of dispersing the pigment component in the liquid medium with a resin component such as a pigment dispersion resin using the disperser in step C, pre-grinding or pretreatment is performed as a pretreatment. It is effective to use the raw material composition obtained through the steps A and B for pre-crushing.

As the processing machine that can be used in the step B, for example, a rotor stator type processing machine, a bead mill processing machine, an ultrasonic disperser, a disper, or the like can be used, and the use of a rotor stator type processing machine is a pigment. Is preferable because it can be pulverized or crushed more efficiently, and as a result, a pigment composition having a reduced number of coarse particles can be efficiently produced.

In the rotor-stator type processing machine, as described later, the coarse particles are crushed or crushed by applying a shearing force to the first raw material composition containing the coarse particles between the rotor and the stator. Ru. Therefore, by passing through the step B and then the step C using the rotor stator type processing machine, the number of coarse particles in the pigment composition can be reduced more efficiently, and the particle diameter is 1.0 μm or more. The number of coarse particles can be further reduced. Further, by passing through the step B after passing through the step B using the rotor stator type processing machine, the coarseness is suppressed by suppressing an increase in the treatment time for obtaining a pigment composition having a small number of coarse particles. A pigment composition having a small number of particles can be obtained with good productivity. Further, by passing through the step B and then the step C using the rotor stator type processing machine, the number of coarse particles having a particle diameter of 0.5 μm or more can be reduced. In evaluating the reduction rate of the number of coarse particles, the reduction rate of the number of coarse particles when the first raw material composition having the same composition is pulverized or crushed is compared. When the pigment composition is processed by various processing machines, the difference in performance of the processing machines can be compared by using the rotation speed of about 80% of the maximum rotation speed.

By passing through the step B and then the step C using the rotor stator type processing machine, the number of coarse particles in the pigment composition can be efficiently reduced while reducing the viscosity of the pigment composition. By passing through the step B and then the step C using the rotor stator type processing machine, the particle size of the solid content in the pigment composition obtained by the pulverization treatment or the crushing treatment can be reduced. .. According to the step C after the step B using the rotor stator type processing machine, the pigment composition obtained by the pulverization treatment or the crushing treatment has excellent storage stability (dispersion stability of solid content). Gender) can be obtained.

According to the process B after the process B using the rotor stator type processing machine, the composition of the pigment composition and the mass ratio of the resin component such as the pigment dispersion resin to the pigment component are the same. High print density can be obtained when compared under the conditions. Further, by passing through the step B and then the step C using the rotor stator type processing machine, it is possible to obtain a high adsorption rate of the resin component such as the pigment dispersion resin with respect to the pigment component.

In the present invention, in the step B, a second raw material composition obtained by previously pulverizing or crushing the pigment using a rotor stator type processing machine, a bead mill processing machine, an ultrasonic processing machine, or a disper is used, and the step C is used. It is possible to efficiently further reduce the number of coarse particles in the pigment composition. Further, in the step B, a rotor stator type processing machine, a bead mill processing machine, or an ultrasonic processing machine is used, and a second raw material composition obtained by crushing or crushing the pigment in advance is used, and the process C is performed. , The time for producing a pigment composition having desired physical properties (number of coarse particles, particle size, etc.) of solid content can be shortened.

In the step B, the temperature in the treatment step using the treatment machine is a pigment composition having desired physical properties (number of coarse particles, particle size, etc.) of the solid content from the viewpoint of easily reducing the number of coarse particles efficiently. From the viewpoint of easily shortening the time required for obtaining through C, and by promoting the dissolution of the resin component such as the pigment-dispersed resin, the adsorption rate of the resin component such as the pigment-dispersed resin with respect to the pigment component is easily improved, which is excellent. The following range is preferable from the viewpoint that storage stability can be easily obtained. The temperature is preferably 25 ° C. or higher, more preferably 30 ° C. or higher, further preferably 40 ° C. or higher, particularly preferably 50 ° C. or higher, extremely preferably 55 ° C. or higher, and very preferably 60 ° C. or higher. The temperature is preferably 80 ° C. or lower, more preferably 75 ° C. or lower, further preferably 70 ° C. or lower, particularly preferably 65 ° C. or lower, and extremely preferably 60 ° C. or lower. From these viewpoints, the temperature is preferably 25 to 80 ° C, more preferably 50 to 80 ° C, still more preferably 60 to 80 ° C.

The rotor-stator type processor that can be used in the step B includes a rotor having a rotatable blade portion and a stator having a wall portion arranged on the outer peripheral side of the blade portion. The processing machine may be any of a crusher, a crusher, a disperser and the like. The rotor and stator can be of any commercially available shape, and different shapes or combinations of the same shape can be used. Since there are differences in the transportability, shear rate (miniaturization ability), calorific value at the time of miniaturization, etc. of the raw material composition depending on the shape, the combination can be selected according to the properties of the first raw material composition. .. Usually, a rotor with a large number of teeth tends to be finely divided, and the amount of heat generated is large.

FIG. 1 (FIGS. 1A and 1B) is a schematic cross-sectional view showing an example of a rotor stator type processing machine. The rotor stator type processing machine 100 shown in FIG. 1 includes a central shaft 10, a rotor 20, and a stator 30. Examples of the constituent materials of the central shaft 10, the rotor 20, and the stator 30 include metal materials, ceramics, and the like.

The central axis 10 is a long member, and extends in the vertical direction, for example. The central shaft 10 supports the rotor 20 and the stator 30.

The rotor 20 has an annular (for example, annular) blade portion 22 extending in the longitudinal direction of the central shaft 10 on the outer peripheral portion of the rotor 20 and a connecting portion 24 connecting the blade portion 22 and the central shaft 10. There is. The blade portion 22 can rotate about the central axis 10. The blade portion 22 has an opening (through hole) 22a penetrating the blade portion 22, and has, for example, a plurality of openings 22a at intervals (for example, even intervals) along the circumferential direction of the blade portion 22. ing. The opening direction of the opening 22a may be inclined with respect to the radial direction. The vertical end of the opening 22a may be open without the members constituting the rotor 20 being arranged. The number, arrangement and shape of the openings 22a are not particularly limited.

The arrangement and shape of the blade portion in the rotor of the rotor stator type processing machine are not particularly limited. For example, the blade portion is not limited to the annular member arranged on the outer peripheral portion of the rotor, and may have a shape extending from the central portion of the rotor to the outer peripheral portion. The rotor may have a plurality of blade portions having a shape extending from the central portion of the rotor to the outer peripheral portion. The blade portion having a shape extending from the central portion to the outer peripheral portion of the rotor may have a streamlined shape.

The stator 30 has an annular (for example, an annular) wall portion 32 extending in the longitudinal direction of the central axis 10 on the outer peripheral portion of the stator 30, and a connecting portion 34 connecting the wall portion 32 and the central axis 10. There is. The wall portion 32 is arranged on the outer peripheral side of the blade portion 22 in the rotor stator type processing machine 100. The wall portion 32 has an opening (through hole) 32a penetrating the wall portion 32, and has, for example, a plurality of openings 32a at intervals (for example, even intervals) along the circumferential direction of the wall portion 32. ing. The opening direction of the opening 32a may be inclined with respect to the radial direction.

The number, arrangement and shape of the opening of the wall portion in the stator are not particularly limited. FIG. 2 is a schematic side view showing an example of a stator (wall portion of the stator) in a rotor stator type processing machine. Examples of the wall portion of the stator include a wall portion (FIG. 2A) having openings arranged in an array (for example, a rectangular opening such as a square shape), and a plurality of rectangular shapes arranged in a row. Examples thereof include a wall portion having an opening (FIG. 2 (b)), a wall portion having a plurality of circular (for example, a perfect circular) opening arranged in a row (FIG. 2 (c)), and the like. Examples of the shape of the opening include a rectangular shape (square shape, rectangular shape, etc.), a circular shape (perfect circle shape, elliptical shape, etc.), and the like.

The stator may have a plurality of annular (eg, annular) wall portions extending in the longitudinal direction of the central axis at the outer peripheral portion of the stator. For example, the stator may include the above-mentioned wall portion 32 as the first wall portion, and may include a second wall portion arranged on the outer peripheral side of the first wall portion in the rotor stator type processing machine, and may include a rotor stator type. A third wall portion arranged on the outer peripheral side of the second wall portion in the processing machine may be further provided. The number of wall portions is not particularly limited and may be 4 or more.

FIG. 3 is a schematic diagram for explaining a crushing process or a crushing process in the rotor stator type processing machine, and is a schematic diagram showing a part of the outer peripheral portion of the rotor stator type processing machine 100 shown in FIG. 1 in an enlarged manner. be. In the rotor stator type processing machine 100, for example, after the first raw material composition containing the pigment component and the liquid medium is supplied around the central axis 10, as shown in FIG. 3, the first raw material composition is prepared. , The space between the blade portion 22 and the wall portion 32 of the stator 30 is reached via the opening 22a of the blade portion 22 of the rotor 20 (flow path F1 in the figure). Then, in this space, the coarse particles P are crushed or crushed by applying the shearing force generated by the rotational movement of the blade portion 22 to the coarse particles P (solid content). After that, a part of the composition containing the crushed or crushed particles flows out to the outer peripheral side of the wall portion 32 via the opening 32a of the wall portion 32 (flow path F2 in the figure), and the rest of the composition. Further advances in the space between the blade portion 22 and the wall portion 32, and the particles are further crushed or crushed by the shearing force. As a result, the pigment component contained in the first raw material composition is crushed or crushed by the crushing treatment or the crushing treatment of the rotor stator type processing machine 100.

The share rate (miniaturization capacity) given by the processing unit composed of the rotor and the stator is from the viewpoint of easily reducing the number of coarse particles efficiently, from the viewpoint of easily reducing the particle size of the solid content after treatment, and the pigment composition. From the viewpoint of easily reducing the viscosity and easily obtaining excellent storage stability in the pigment composition, 50,000s ^-1 or more is preferable, 75,000s ^-1 or more is more preferable, 90000s ^-1 or more is further preferable, and 100,000s ^-1 or more. The above is particularly preferable, 120,000s ^-1 or more is extremely preferable, 150,000s ^-1 or more is very preferable, and 170000s ^-1 or more is even more preferable. The upper limit of the share rate may be, for example, 400000s ^-1 or less, and may be 250,000s ^-1 or less. From these viewpoints, the share rate is preferably 50,000 to 400,000 s ^-1 . The share rate [s ^-1 ] can be obtained by dividing the peripheral speed [m / s] of the blade portion of the rotor by the distance [m] between the blade portion and the wall portion of the stator.

The rotor-stator type processing machine may have a plurality of processing units (crushing unit or crushing unit) composed of a rotor and a stator. By flowing the first raw material composition from the processing section having a low share rate toward the processing section having a high share rate, clogging can be easily suppressed, so that the number of coarse particles can be easily reduced. The rotor stator type processing machine may have a plurality of processing units along a central axis extending in the vertical direction (may have a multi-stage processing unit). When the rotor stator type processing machine has a plurality of processing units along the central axis, it is preferable to arrange the processing units having a higher share rate toward the lower part in the vertical direction from the viewpoint of easily reducing the number of coarse particles efficiently.

The rotor stator type processing machine may be an in-line type processing machine or a batch type processing machine. In the in-line processing machine, the first raw material composition is continuously supplied, and for example, a processing machine is installed in the middle of a processing path (for example, a crushing processing path and a crushing processing path, for example, piping), and the first. The raw material composition of the above can be continuously processed (crushing treatment or crushing treatment). In the in-line type processing machine, since the entire first raw material composition is forcibly passed through the processing machine, the first raw material is processed in a shorter time than the batch type processing machine in which mainly the periphery of the rotor is processed. It is easy to treat the entire composition uniformly. According to the in-line type processing machine, since it is easy to efficiently reduce the number of coarse particles, it is easy to suppress the clogging of the piping of the processing machine used in the step B. According to the in-line processing machine, it is easy to reduce the viscosity of the pigment composition. In the in-line processing machine, the raw material composition may be circulated. In the batch type processing machine, the raw material composition is intermittently supplied, and the first raw material composition is replaced with each treatment (crushing treatment or crushing treatment).

As a rotor stator type processing machine, the device name "magic LAB" manufactured by IKA Co., Ltd. (in-line type, maximum peripheral speed: 41 m / s, maximum rotation speed: 26000 rpm); device name "VERSO" manufactured by Silverson Nippon Co., Ltd. (High shear inline mixer, inline type, maximum peripheral speed: 20 m / s, maximum rotation speed: 10000 rpm); Equipment name "L5MA" manufactured by Silverson Nippon Co., Ltd. (batch type, maximum peripheral speed: 20 m / s, Maximum rotation speed: 10000 rpm) and the like. As the processing machine manufactured by IKA Co., Ltd., a processing machine including a UTR module (ULTRA-TURRAX), a DR module (DISPAX-RECTOR), an MK module, an MKO module, and a CMX module can be used. Since the DR module has three processing units (stages) composed of a rotor and a stator and the share rate can be adjusted by the combination of the rotor and the stator, it is easy to efficiently reduce the number of coarse particles. For example, by using the 2P / 4M / 6F processing units in order from the upper part in the vertical direction, it is possible to arrange the processing units having a higher share rate toward the lower part in the vertical direction.

As the rotor stator type processing machine, it is preferable to use one having a maximum rotation speed in the range of 1000 to 30000 rpm, more preferably to use one having a maximum rotation speed in the range of 3000 to 25000 rpm, and one having a maximum rotation speed in the range of 8000 to 20000 rpm. From the viewpoint that it is easy to efficiently reduce the number of coarse particles, the viewpoint that it is easy to reduce the particle size of the solid content after treatment, the viewpoint that it is easy to reduce the viscosity of the pigment composition, and the excellent storage in the pigment composition. It is particularly preferable from the viewpoint of easily obtaining stability.

As the rotor stator type processing machine, it is preferable to use one having a maximum peripheral speed in the range of 5 m / s to 60 m / s, and more preferably to use one having a maximum peripheral speed in the range of 10 m / s to 60 m / s. Using a pigment in the range of 15 m / s to 60 m / s reduces the number of coarse particles efficiently, the particle size of the solid content after treatment can be easily reduced, and the viscosity of the pigment composition can be reduced. It is particularly preferable from the viewpoint of ease of use and the viewpoint of easily obtaining excellent storage stability in the pigment composition.

The raw material supply unit in the pigment composition manufacturing apparatus according to the present embodiment is not particularly limited as long as the first raw material composition can be supplied to the rotor stator type processing machine. The raw material supply unit may be a pipe, a pump, or the like that supplies the raw material supply unit.

Further, as the bead mill disperser, for example, a paint shaker, a bead mill, a sand mill, a basket mill, a dyno mill, an SC mill, a nano mill, a spike mill, an agitator mill and the like can be used.

Further, as the ultrasonic disperser, a device name "UP200St" manufactured by Heelsher or the like can be used.

Further, as the disper, a device name "Homo Disper" manufactured by Primix Corporation, a device name "Disper Mat" manufactured by Eiko Seiki Co., Ltd., or the like can be used.

Next, the step C will be described.

The step C has a structure in which the second raw material composition obtained in the step B is made to collide with each other or the second raw material composition is made to collide with a hard body. This is the process of processing with a disperser.

Among the dispersers used in the step C, as a disperser having a configuration in which the second raw material compositions collide with each other, a dispersion having a configuration in which the second raw material compositions collide with each other in an oblique direction. It is particularly preferable to use a machine in order to reduce the number of coarse particles in the pigment composition, reduce the particle size of the dispersed particles, and improve the production efficiency of the pigment composition. More specifically, by using a disperser having a configuration in which the second raw material compositions collide with each other in an oblique direction, the second raw material composition is repeatedly charged into the disperser and processed. The number of times (so-called number of passes) can be significantly reduced from about 10 to 30 times in the past, preferably 1 to 8 times, more preferably 1 to 5 times, and particularly preferably 1 to 3 times. In particular, when carbon black is used as the pigment component, it is possible to obtain a pigment composition that achieves both a reduction in the number of coarse particles and a small particle size in the dispersed particle size with only one pass. An oblique collision chamber can be mentioned as a configuration for obliquely colliding the second raw material compositions with each other. When the disperser is used, the second raw material compositions can collide with each other by pressure-injecting the raw material compositions from a plurality of directions.

Examples of the oblique collision chamber include a chamber having the device name "Starburst" manufactured by Sugino Machine Limited. The oblique collision chamber is preferable because it can avoid wear of a hard body, which will be described later, when used for a long time, and can obtain a shearing force superior to that of a single nozzle chamber.

Specifically, as the disperser, the device name "Starburst" manufactured by Sugino Machine Limited can be used.

Further, the disperser used in the present invention is a so-called high-pressure homogenizer capable of applying a pressure in the range of 50 to 245 MPa when injecting the second raw material composition, which is the coarseness in the pigment composition. It is preferable in order to achieve both a reduction in the number of particles and an improvement in the production efficiency of the pigment composition. The pressure is more preferably 80 to 200 MPa, further preferably 100 to 200 MPa, and particularly preferably 130 to 200 MPa. When the pigment component contains carbon black, it is possible to obtain a pigment composition that can be ejected by inkjet at low pressure and has excellent storage stability, prolonging the life of the apparatus, and increasing the production amount per unit time. Easy to achieve improvement.

As the second raw material composition, one containing a solid content such as a pigment component or a resin component and a liquid medium, and further containing an additive other than these can be used. The pigment composition can contain the same kind of components as the raw material composition. The solid content concentration of the raw material composition is preferably in the range of 1 to 60% by mass, more preferably in the range of 10 to 50% by mass, and more preferably 15 to 40% by mass, based on the total amount of the raw material composition. It is particularly preferable to be in the range of%.

The pigment composition obtained by the above method is diluted with the above-mentioned liquid medium to a desired concentration, and / or a resin component (binder such as an acrylic resin or a polyurethane resin), a drying inhibitor, or a penetrant. It can be used as an ink by adding additives such as a surfactant, a preservative, a viscosity regulator, a pH regulator, a chelating agent, a plasticizer, an antioxidant, and an ultraviolet absorber. After obtaining the ink, a centrifugation treatment or a filtration treatment may be performed.

Examples of the ink include paints for automobiles or building materials; printing inks such as inkjet printing inks, offset inks, gravure inks, flexo inks, and silk screen inks. When the ink is used as an ink for inkjet printing, the content of the pigment component in the ink is preferably 1 to 10% by mass based on the total amount of the ink.

Examples of the anti-drying agent include glycerin, ethylene glycol, diethylene glycol, triethylene glycol, triethylene glycol mono-n-butyl ether, polyethylene glycol having a molecular weight of 2000 or less, propylene glycol, dipropylene glycol, tripropylene glycol, and 1,3-propylene glycol. , Isopropylene glycol, isobutylene glycol, 1,4-butanediol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, mesoerythritol, pentaerythritol and the like. As the anti-drying agent, the same compound as the above-mentioned water-soluble organic solvent used in the raw material composition can be used. Therefore, when a water-soluble organic solvent is already used in the raw material composition, it can also serve as a drying inhibitor.

The penetrant can be used for the purpose of improving the permeability to the recording medium or adjusting the dot diameter on the recording medium. Examples of the penetrant include lower alcohols such as ethanol and isopropyl alcohol; glycol monoethers of alkyl alcohols such as ethylene glycol hexyl ether, diethylene glycol butyl ether and propylene glycol propyl ether.

Surfactants can be used to adjust ink properties such as surface tension. The surfactant is not particularly limited, and examples thereof include various anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, and the like, and anionic surfactants and nonionic surfactants. At least one selected from the group consisting of sex surfactants is preferred. The surfactant may be used alone or in combination of two or more.

Anionic surfactants include alkylbenzene sulfonates, alkylphenylsulfonates, alkylnaphthalene sulfonates, higher fatty acid salts, higher fatty acid ester sulfates, higher fatty acid ester sulfonates, higher alcohol ether sulfates. Examples thereof include ester salts and sulfonates, higher alkyl sulfosuccinates, polyoxyethylene alkyl ether carboxylates, polyoxyethylene alkyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates and the like. Specific examples of these include dodecylbenzene sulfonate, isopropylnaphthalene sulfonate, monobutylphenylphenol monosulfonate, monobutylbiphenylsulfonate, dibutylphenylphenol disulfonate and the like.

Nonionic surfactants include polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester, and poly. Oxyethylene glycerin fatty acid ester, polyglycerin fatty acid ester, sucrose fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene fatty acid amide, fatty acid alkyrrole amide, alkyl alkanolamide, acetylene glycol, oxyethylene adduct of acetylene glycol, polyethylene glycol Polyethylene glycol block copolymer and the like can be mentioned. Among these, polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, fatty acid. At least one selected from the group consisting of alkyrrole amide, acetylene glycol, oxyethylene adduct of acetylene glycol, and polyethylene glycol polypropylene glycol block copolymer is preferable.

Other surfactants include silicone-based surfactants such as polysiloxane oxyethylene adducts; fluorine-based surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and oxyethylene perfluoroalkyl ethers; Biosurfactants such as sulphonic acid, ramnolipide, and lysolecithin can also be used.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these Examples.
<Preparation of styrene-acrylic acid-based copolymer>
(Styrene-acrylic acid-based copolymer A)
After charging 100 g of methyl ethyl ketone into a reaction vessel equipped with a stirrer, a dropping device and a refluxing device, the inside of the reaction vessel was replaced with nitrogen while stirring. Next, with the reaction vessel heated and the methyl ethyl ketone refluxed, 77 g of styrene, 10 g of acrylic acid, 13 g of methacrylic acid and a polymerization catalyst (manufactured by Wako Pure Chemical Industries, Ltd., trade name: V-59) 8 g from the dropping device. The mixed solution of Wako Pure Chemical Industries, Ltd. was added dropwise over 2 hours. The temperature of the reaction vessel was kept at 80 ° C. from the middle of the dropping. After completion of the dropping, the reaction was continued at the same temperature for 25 hours. After completion of the reaction, the inside of the reaction vessel was allowed to cool, and then methyl ethyl ketone was added to obtain a solution having a solid content concentration of 50% by mass. Further, after drying this solution, it was pulverized into a powder of 1 mm or less to obtain a styrene-acrylic acid copolymer A. The acid value of the styrene-acrylic acid copolymer A was 150 mgKOH / g, and the weight average molecular weight was 8800.

The weight average molecular weight is a value measured by a GPC (gel permeation chromatography) method, and is a value converted to the molecular weight of polystyrene used as a standard substance. The measurement was performed with the following equipment and conditions.

Liquid transfer pump: LC-9A (manufactured by Shimadzu Corporation)
System controller: SLC-6B (manufactured by Shimadzu Corporation)
Auto injector: S1L-6B (manufactured by Shimadzu Corporation)
Detector: RID-6A (manufactured by Shimadzu Corporation)
Data processing software: Sic480II data station (manufactured by System Instruments)
Column: GL-R400 (guard column) + GL-R440 + GL-R450 + GL-R400M (manufactured by Hitachi Kasei Co., Ltd.)
Elution solvent: THF (tetrahydrofuran)
Elution flow rate: 2 mL / min
Column temperature: 35 ° C

<Preparation of pigment composition>
(Black pigment composition)
[Example A1]
First, 110.0 g of triethylene glycol (δD16.5, δP12.5, δH18.5), 232.2 g of ion-exchanged water and 17.8 g of a 34 mass% potassium hydroxide aqueous solution are mixed to prepare a mixture. The first raw material composition (pigment) is obtained by mixing 100.0 g of a black pigment (carbon black, # 960, dry pigment) manufactured by Mitsubishi Chemical Corporation and 40 g of the above-mentioned styrene-acrylic acid-based copolymer A with the mixture. Concentration: 20% by mass, solid content concentration: 28% by mass) was prepared.

Next, in the step B, a rotor stator type processing machine (manufactured by IKA Co., Ltd., device name: magic LAB, 3-stage type, 2P / 4M / 6F processing unit (rotor and stator), in-line type, in order from above in the vertical direction). ) The first raw material composition was put into. Next, a second raw material composition (slurry) was prepared by performing a 5-pass treatment at a peripheral speed of 34 m / s (share rate: 170000s ^-1 ) and a rotation speed of 20000 rpm while heating to 60 ° C.

Next, in the step C, a process of ejecting and colliding the second raw material composition at a pressure of 140 MPa using a high-pressure homogenizer (equipment name: Starburst, oblique collision chamber) manufactured by Sugino Machine Limited. A pigment composition was obtained by applying 1 pass.

[Example A2]
A pigment composition was obtained in the same manner as in Example A1 except that dipropylene glycol (δD17.0, δP8.4, δH15.9) was used instead of triethylene glycol.

[Example A3]
A pigment composition was obtained in the same manner as in Example A1 except that it was changed to 1,5-pentanediol (δD17.0, δP8.9, δH19.8) instead of triethylene glycol.

[Example A4]
A pigment composition was obtained in the same manner as in Example A1 except that propylene glycol (δD16.8, δP10.4, δH21.3) was used instead of triethylene glycol.

[Comparative Example A1]
A pigment composition was obtained in the same manner as in Example A1 except that the triethylene glycol was changed to methyl ethyl ketone (δD16.0, δP9.0, δH5.1).

[Comparative Example A2]
A pigment composition was obtained in the same manner as in Example A1 except that it was changed to ethylene glycol (δD16.8, δP15.8, δH27.7) instead of triethylene glycol.

[Comparative Example A3]
A pigment composition was obtained in the same manner as in Example A1 except that it was changed to N-methyl-2-pyrrolidone (δD18.0, δP12.3, δH7.2) instead of triethylene glycol.

<Evaluation of pigment composition>
The number of coarse particles, particle size, viscosity, storage stability, and print density of the pigment composition obtained in Examples and Comparative Examples and the raw material composition in the process of production were measured by the following methods. The results are shown in Tables 1 and 2.

(Number of coarse particles)
The number of particles having a diameter of 1.0 μm or more and the number of particles having a diameter of 0.5 μm or more were measured by a particle size distribution meter (manufactured by Particle Sizes Systems, Accuser 780 APS, number counting method) by the following procedure. The pigment composition was diluted with ion-exchanged water so that the sensitivity was in the range of 1000 to 4000 pieces / mL. Next, using a particle size distribution meter, the number of particles having a diameter of 1.0 μm or more and the number of particles having a diameter of 0.5 μm or more contained in the diluted pigment composition were measured three times. Subsequently, the average value of the values obtained by multiplying the measured value of the number of particles by the dilution concentration was calculated as the number of coarse particles.

(Particle size)
The pigment composition was placed in a cell of about 4 mL. The particle size was measured by detecting scattered light of laser light in an environment of 25 ° C. using a nanotrack particle size distribution meter "UPA150" manufactured by Microtrac Bell Co., Ltd. As the particle diameter, the volume average particle diameter (Mv), the number average particle diameter (Mn), D50, D90 and D95 were measured.

(viscosity)
After 1.0 mL of the pigment composition was placed in a sample cup, the viscosity of the pigment composition was measured using a TV-20 type viscometer manufactured by Toki Sangyo Co., Ltd. in an environment of 25 ° C.

(Storage stability)
The volume average particle size (Mv), viscosity, and number of coarse particles having a diameter of 0.5 μm of the pigment composition immediately after production were measured by the above-mentioned method.

Next, the pigment composition was sealed in a polypropylene container and then stored at 60 ° C. for 4 weeks. The volume average particle size (Mv), viscosity, and number of coarse particles having a diameter of 0.5 μm of the pigment composition after storage were measured by the method described above.

Volume average particle size (Mv), viscosity, and diameter of the pigment composition after storage with respect to the volume average particle size (Mv), viscosity, and number of coarse particles having a diameter of 0.5 μm immediately after production. The rate of change in the number of coarse particles of 0.5 μm was calculated.

Those having a rate of change within the range of 10% can be evaluated as having excellent storage stability, those having a rate of change of more than 10% and within 15% can be evaluated as having good storage stability, and those having a rate of change exceeding 15% can be evaluated as having good storage stability. It was evaluated that the storage stability was not sufficient.

10 ... central axis, 20 ... rotor, 22 ... blade part, 22a ... opening, 24 ... connection part, 30 ... stator, 32 ... wall part, 32a ... opening, 34 ... connection part, 100 ... rotor stator type processing machine, F1 , F2 ... Channel.

Claims (7)

Step A for producing a first raw material composition by mixing a resin component, a pigment component, a basic compound, and a liquid medium, a rotor stator type processing machine or a bead mill processing machine for producing the first raw material composition. Alternatively, the step B for producing the second raw material composition by processing with an ultrasonic processing machine or a disper, and the configuration in which the second raw material composition collides with each other or the first Production of a pigment composition in which the pigment component is dispersed in a liquid medium by the resin component, which comprises a step C of treating the raw material composition of No. 2 with a disperser having a structure for colliding with a hard body. In the method, the liquid medium has a dispersion term (δD ¹ ) in the range of 16 to 19, a polar term (δP ¹ ) in the range of 8 to 13, and a hydrogen bond term (δH ¹ ) in the range of 9 to 30. A method for producing a pigment composition, which comprises a liquid medium (a) comprising). Claim 1 in which the liquid medium (a) is triethylene glycol, 2-pyrrolidone, 1- (2-hydroxyethyl) -2-pyrrolidone, dipropylene glycol, propylene glycol, 1,5-pentanediol or glycerin. The method for producing a pigment composition according to the above. The method for producing a pigment composition according to claim 1 or 2, wherein the mass ratio of the liquid medium (a) to the total amount of the liquid medium contained in the pigment composition is in the range of 15 to 80% by mass. The method for producing a pigment composition according to any one of claims 1 to 3, wherein the disperser having a configuration in which the second raw material composition collides with each other is an oblique collision type disperser. The method for producing a pigment composition according to claim 4, wherein the oblique collision type disperser has a configuration in which the second raw material compositions collide with each other at a pressure in the range of 50 to 245 MPa. Claimed that the number of times (number of passes) of repeatedly charging the second raw material composition into a disperser provided with a configuration for obliquely colliding the second raw material compositions with each other and processing the second raw material composition is in the range of 1 to 8 times. Item 4. The method for producing a pigment composition according to Item 4. The method for producing a pigment composition according to any one of claims 4 to 6, wherein the pigment composition is a pigment composition for inkjet printing ink.

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