JP6829286B2 - Aqueous pigment dispersion - Google Patents

Description

The present invention relates to an aqueous pigment dispersion, particularly an aqueous pigment dispersion for an emulsion polymerization toner. More specifically, the present invention relates to an aqueous pigment dispersion liquid which is excellent in pigment yield and particle size control during the production of an emulsion polymerization toner and is useful as a material or the like when the emulsion polymerization toner is produced.

Conventionally, as toner for electrophotographic copiers and printers, a binder resin and a pigment are mixed, and if necessary, a charge control agent, a magnetic substance, a wax component, and other materials are further mixed, melt-kneaded, and then pulverized. And pulverized toner obtained by classification has been used. In recent years, polymerized toners have been proposed in order to improve the image quality by miniaturizing the toner particles and controlling the particle size. Polymerized toner is roughly classified into emulsion polymerization toner and suspension polymerization toner. Of these, the emulsion-polymerized toner is obtained by adding an aqueous dispersion of pigments (aqueous pigment dispersion) and other components to an emulsion of a binder resin obtained by emulsion polymerization, and then coagulating and fixing the mixture to a desired particle size. (Patent Documents 1 to 3).

Japanese Unexamined Patent Publication No. 11-143125 Japanese Unexamined Patent Publication No. 2001-5218 Japanese Unexamined Patent Publication No. 2001-324834

In the methods proposed in Patent Documents 1 to 3, surfactants such as sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, and polyoxyethylene nonylphenyl ether are used as the dispersant for dispersing the pigment in the aqueous dispersion of the pigment. Has been done. However, when an emulsion-polymerized toner is prepared using such an aqueous dispersion of a pigment, there is a problem that the pigment is difficult to aggregate in the process of coagulating and fixing the toner particles, and the yield of the pigment tends to decrease. In addition, there is a problem that it is difficult to control the particle size of the generated toner particles.

By the way, as the toner, four colors, an yellow color, a magenta color, a cyan color, and a black color, are usually used as basic colors. Among them, as a pigment exhibiting an yellow color, an azo pigment such as Pigment Yellow 74 is generally used. However, in consideration of the influence on the environment, it tends to be necessary to use a non-azo pigment as an yellow pigment (yellow pigment). In particular, the use of Pigment Yellow 185, which is an isoindoline-based pigment, has been studied in terms of weather resistance, color development, and hue. However, since Pigment Yellow 185 is highly hydrophilic and has poor alkali resistance, it is difficult to prepare a high-concentration aqueous pigment dispersion. Further, Pigment Yellow 185 has a problem that the dispersion stability is low.

The present invention has been made in view of the problems of the prior art, and the problem is that the pigment is finely dispersed and the viscosity and the particle size of the pigment are hard to fluctuate, so that the pigment is preserved. It is an object of the present invention to provide an aqueous pigment dispersion liquid which is excellent in stability and can prepare an emulsion polymerization toner having an appropriately controlled particle size while improving the yield of the pigment.

That is, according to the present invention, the following aqueous pigment dispersion liquid is provided.
[1] An aqueous pigment dispersion containing a pigment, a dispersant for dispersing the pigment, and an aqueous medium containing water, wherein the dispersant is one of the following molecular chains (i) to (iii). It is derived from a structural unit (A) derived from a monomer (A) in which a group containing a (meth) acryloyloxy group or a (meth) acryloylamino group is bonded to one end, and a monomer (B) having a carboxy group or an amino group. It is a polymer containing a structural unit (B), and the content of the oxyethylene unit derived from the monomer (A) in the polymer is 50 to 90% by mass based on the total mass of the polymer. (2-1) AB block copolymer, (2-2), wherein the polymer has (2) a polymer block A containing the structural unit (A) and a polymer block B containing the structural unit (B). ABA block copolymer, or (2-3) a graft copolymer in which the polymer block A is grafted with the polymer block B as the main chain, and the polystyrene-equivalent value of the polymer measured by gel permeation chromatography. An aqueous pigment dispersion having a number average molecular weight of 4,000 to 15,000, the polymer being contained in a substantially unionized state, and a pH of 3.0 to 8.4.
(I) Polyethylene glycol chain having an average number of repetitions n of oxyethylene units of 4 to 20 (ii) Polyethylene glycol monoalkyl (carbon number 1 to 18) ether chain having an average number of repetitions n of 4 to 9 of oxyethylene units (Iii) Oxyethylene The molecular chain R-represented by the following general formula (1), in which the average number of repetitions n of the oxyethylene oxypropylene unit is 20 to 50 and the content of the oxyethylene unit is 70 to 92% by mass. (OEt) _x- (OPr) _y- A ... (1)
(In the general formula (1), R represents an alkyl group having 1 to 18 carbon atoms, A represents OH or NH ₂ , Et represents an ethylene group, Pr represents a propylene group, and x + y = n. )

[2] The aqueous pigment dispersion according to the above [1], which is a pigment dispersion for an emulsion polymerization toner .
[3 ] The monomer (B) is at least one selected from the group consisting of (meth) acrylic acid or vinylpyridine, vinylimidazole, and dimethylaminoethyl (meth) acrylate, and the above-mentioned composition in the polymer. The aqueous pigment dispersion according to the above [1] or [ 2] , wherein the content of the unit (B) is 3 to 15% by mass based on the total mass of the polymer.
[ 4 ] The aqueous pigment dispersion according to any one of [1] to [ 3 ], wherein the pigment is a yellow pigment containing Pigment Yellow 185, and the monomer (B) is a monomer having an amino group. ..
[ 5 ] The aqueous pigment dispersion according to any one of [1] to [ 4 ], wherein the number average particle size of the pigment measured by a light scattering method is 80 to 300 nm.
[ 6 ] Of the above [1] to [ 5 ], the content of the pigment is 10 to 40% by mass, and the content of the dispersant is 5 to 60% by mass based on the content of the pigment. The aqueous pigment dispersion according to any one.
[ 7 ] The aqueous pigment dispersion according to any one of [1] to [ 6 ], wherein the pigment is Pigment Yellow 185 and the content of the pigment is 20 to 40% by mass.

According to the present invention, the pigment is finely dispersed, the viscosity and the particle size of the pigment are less likely to fluctuate, the storage stability is excellent, and the emulsion polymerization toner in which the particle size is appropriately controlled can be used to obtain the pigment yield. It is possible to provide an aqueous pigment dispersion that can be prepared while improving.

<Aqueous pigment dispersion>
Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to the following embodiments. The aqueous pigment dispersion of the present invention is an aqueous pigment dispersion useful as one of the raw materials for producing an emulsion polymerization toner. The emulsion polymerization toner can be produced by a conventionally known method for producing a toner using emulsion polymerization. Specifically, the emulsion prepared by using the nonionic surfactant is heated above the cloud point of the nonionic surfactant, the nonionic surfactant is water-insoluble to aggregate the emulsion particles, and the toner particles are agglomerated. There are ways to get it. In addition, there are a method of adding a salt to precipitate toner particles; a method of adding an acid or a base to precipitate toner particles; a method of adding a poor solvent to precipitate toner particles; and the like. Among them, the aqueous pigment dispersion of the present invention is suitable as one of the raw materials for producing an emulsion polymerization toner by a method using a cloud point or a method of adding a salt. That is, the dispersant for dispersing the pigment used in the aqueous pigment dispersion of the present invention is designed so as to be able to stably finely disperse the pigment at a high concentration and to be suitable for a method for producing an emulsion polymerization toner. ing.

That is, the pigment dispersant of the present invention is an aqueous pigment dispersion liquid containing a pigment, a dispersant for dispersing the pigment, and an aqueous medium containing water. The dispersant is a polymer containing a structural unit (A) derived from the monomer (A) and a structural unit (B) derived from the monomer (B). The monomer (A) is a monomer in which a group containing a (meth) acryloyloxy group or a (meth) acryloylamino group is bonded to one end of any of the following molecular chains (i) to (iii). Further, the monomer (B) is a monomer having a carboxy group or an amino group.
(I) Polyethylene glycol chain having an average number of repetitions n of 4 to 20 in oxyethylene units (ii) Polyethylene glycol monoalkyl (1 to 18 carbon atoms) ether chain having an average number of repetitions n of 4 to 20 in oxyethylene units (Iii) Oxyethylene The molecular chain R-represented by the following general formula (1), in which the average number of repetitions n of the oxyethylene oxypropylene unit is 20 to 50 and the content of the oxyethylene unit is 70 to 92% by mass. (OEt) _x- (OPr) _y- A ... (1)
(In the general formula (1), R represents an alkyl group having 1 to 18 carbon atoms, A represents OH or NH ₂ , Et represents an ethylene group, Pr represents a propylene group, and x + y = n. )

The content of the oxyethylene unit derived from the monomer (A) in the polymer used as the dispersant is 50 to 90% by mass based on the total mass of the polymer, and is measured by gel permeation chromatography (GPC) of the polymer. The polystyrene-equivalent number average molecular weight to be obtained is 4,000 to 15,000. In addition, the polymer is contained in the aqueous pigment dispersion in a substantially unionized state. The pH of the aqueous pigment dispersion at 25 ° C. is 3.0 to 8.4. Hereinafter, the details of the aqueous pigment dispersion liquid of the present invention will be described.

(Monomer (A))
The dispersant for dispersing the pigment is a polymer containing a structural unit (A) derived from the monomer (A). The monomer (A) is a monomer in which a group containing a (meth) acryloyloxy group or a (meth) acryloylamino group is bonded to one end of any of the above-mentioned molecular chains (i) to (iii). The content of the oxyethylene unit derived from the monomer (A) in the polymer is 50 to 90% by mass based on the total mass of the polymer. The aqueous pigment dispersion of the present invention using such a polymer as a dispersant for dispersing the pigment is suitable as an aqueous pigment dispersion used as a raw material in producing an emulsion polymerization toner. Among them, the aqueous pigment dispersion of the present invention is particularly suitable as a pigment dispersion used as a raw material when producing an emulsion polymerization toner by the above-mentioned method utilizing a cloud point.

Since the polymer used as the dispersant contains oxyalkylene units (alkylene glycol chains) such as oxyethylene units and oxypropylene units, it is highly hydrophilic and can be dissolved in water. Further, the alkylene glycol chain usually breaks hydrogen bonds at a specific temperature determined according to the amount of oxyethylene units (average number of repetitions n) and the molecular weight, and becomes insoluble in water. The specific temperature at which the hydrogen bond is broken and becomes insoluble in water is the cloud point, and the polymer used as the dispersant has the cloud point. The cloud point is preferably 50 to 90 ° C. That is, the type, molecular weight, composition, content of oxyethylene units, and the like of the alkylene glycol chain are controlled so that the polymer used as the dispersant in the aqueous pigment dispersion of the present invention has a predetermined cloud point.

Specific examples of the molecular chains such as the glycol chains (i) and (ii) are polyethylene glycol chains, polyethylene glycol monomethyl ether chains, polyethylene glycol monobutyl ether chains, and polyethylene glycol having an average molecular weight of about 160 to 1,000. Examples thereof include monododecyl ether chains, polyethylene glycol monooctadecyl ether chains, and polyethylene glycol monooleyl ethers.

The molecular chain of (iii) represented by the general formula (1) has an average molecular weight of preferably about 1,000 to 2,000, and an oxyethylene unit: an oxypropylene unit (molar ratio) is preferable. Is 1: 1 to 11: 1. Further, the sequences of "OEt" (oxyethylene unit) and "OPr" (oxypropylene unit) in the general formula (1) may be random or block. In the general formula (1), specific examples of the alkyl group having 1 to 18 carbon atoms represented by R include a methyl group, a propyl group, a butyl group, a dodecyl group, and an octadecyl group.

The content of the oxyethylene unit derived from the monomer (A) in the polymer is 50 to 90% by mass, preferably 50 to 70% by mass, based on the total mass of the polymer. If the content of oxyethylene units is too low, the polymer becomes water-insoluble and does not function as a dispersant. On the other hand, if the content of the oxyethylene unit is too large, the water solubility of the polymer becomes too high and cloud points do not appear, making it difficult to use in the production of emulsion polymerized toner.

Among the molecular chains of (i) to (iii), the molecular chain of (iii) has a large molecular weight and is more effective in suppressing pigment aggregation due to steric hindrance, so that the storage stability of the aqueous pigment dispersion is improved. It is preferable to further improve. The content of the oxyethylene unit in these molecular chains, the average number of repetitions n of the oxyalkylene unit, and the like can be calculated from, for example, the proton ratio of ¹ H-NMR.

The monomer (A) is a monomer in which a group (polymerizable group) containing a (meth) acryloyloxy group or a (meth) acryloylamino group is bonded to one end of any of the molecular chains (i) to (iii). is there. If the polymerizable group bonded to one end of the molecular chain is a vinyl group or an allyl group, the polymerization becomes insufficient and it tends to remain. As the polymerizable group, a methacryloyloxy group and a methacryloylamino group are preferable.

The molecular chain and the (meth) acryloyloxy group or the (meth) acryloylamino group may be directly bonded, or may be bonded with other organic groups interposed therebetween. For example, the hydroxyl group at the molecular chain terminals (OH group) or an amino group (NH ₂ group) (meth) were reacted acryloyloxyethyl isocyanate, it may be interposed a urethane bond or a urea bond. Further, a hydroxyl group and an amino group may be formed by causing a ring-opening reaction of glycidyl methacrylate with an amino group ( ₂ NH groups) at the end of the molecular chain.

(Monomer (B))
The polymer used as a dispersant contains a structural unit (B) derived from the monomer (B). The monomer (B) is a monomer having a carboxy group or an amino group. By using the monomer (B), a carboxy group as an acid group or an amino group as a basic group can be introduced into the molecular skeleton of the polymer used as a dispersant.

A polymer having a carboxy group or an amino group introduced therein is easily adsorbed on the surface of the pigment because these groups are hydrogen-bonded or ionic-bonded to the pigment. Therefore, by using a polymer having a carboxy group or an amino group introduced as a dispersant, the fine dispersibility and storage stability of the aqueous pigment dispersion can be improved. It is preferable to use the carboxy group and the amino group properly depending on the surface properties (acidic, basic) of the pigment. When a pigment whose surface is acidic is dispersed, it is preferable to use a basic polymer containing a structural unit (B) derived from a monomer (B) having an amino group as a dispersant. On the other hand, when a pigment whose surface is basic is dispersed, it is preferable to use an acidic polymer containing a structural unit (B) derived from a monomer (B) having a carboxy group as a dispersant.

It is preferable that the carboxy group and amino group introduced into the polymer are neutralized and not ionized. That is, the polymer used as the dispersant is contained in the aqueous pigment dispersion in a state where it is not substantially ionized. When the carboxy group and the amino group are neutralized to become water dissociative, the polymer that functions as a dispersant dissolves in water, and even if the temperature rises above the cloud point, toner particles are less likely to precipitate. If both a carboxy group and an amino group are introduced into the polymer, one of them will be ionized, which is not preferable. Further, when an acidic group such as a sulfonic acid group or a phosphoric acid group is introduced into the polymer instead of the carboxy group, these acidic groups are highly hydrophilic without being neutralized, and the polymer dissolves in water. There is. Therefore, the acidic group of the monomer (B) is preferably a carboxy group.

Among the monomers (B), examples of the monomer having a carboxy group include (meth) acrylic acid; (meth) acrylate containing a hydroxy group such as 2-hydroxyethyl (meth) acrylic acid, and succinic acid, maleic acid, and phthalic acid. , Acid group-containing methacrylate obtained by reacting a polybasic acid such as trimeritic acid; Acid group-containing methacrylate obtained by reacting an epoxy group-containing methacrylate such as glycidyl (meth) acrylate with a polybasic acid; Can be done. Of these, (meth) acrylic acid is preferable because it does not have an ester bond and is difficult to hydrolyze in an aqueous pigment dispersion.

Among the monomers (B), the monomers having an amino group include 2-vinylpyridine, 4-vinylpyridine, vinylimidazole, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, and (meth) acrylic acid. t-Butylaminoethyl, an amino group-containing monomer obtained by reacting glycidyl (meth) acrylate with ammonia, dimethylamine, etc., (meth) acryloyloxyethyl isocyanate with a primary or secondary amino group and a tertiary Examples thereof include a monomer obtained by reacting a compound having an amino group. The pH of the aqueous pigment dispersion is 3.0 to 8.4 (within the range of acidic to weakly alkaline). If the basicity of the amino group is too strong, the pH of the obtained aqueous pigment dispersion tends to deviate from the above range. Therefore, as the monomer (B), at least one selected from the group consisting of vinylpyridine, vinylimidazole, and dimethylaminoethyl (meth) acrylate having a weakly basic amino group is preferable.

The content of the structural unit (B) derived from the polymer (B) in the polymer is preferably 3 to 15% by mass, more preferably 5 to 10% by mass, based on the total mass of the polymer. .. If the content of the structural unit (B) in the polymer is less than 3% by mass, the adsorptivity of the polymer to the surface of the pigment tends to decrease, and the dispersion stability of the pigment may be slightly impaired. On the other hand, when the content of the structural unit (B) in the polymer is more than 15% by mass, the hydrophilicity of the polymer tends to increase, and even if the temperature rises above the cloud point, precipitation may be difficult. Further, if the content of the structural unit (B) in the polymer is too large, the pH of the aqueous pigment dispersion tends to be excessively high.

(Monomer (C))
The polymer used as a dispersant may further contain a structural unit (C) derived from the monomer (A) and the monomer (C) which is a monomer other than the monomer (B), if necessary. The monomer (C) is preferably a monomer that does not exhibit an acidic group, a basic group, and a reactive group such as an isocyanate group or an epoxy group. Examples of the monomer (C) include vinyl-based monomers such as styrene, vinyltoluene, vinyl acetate, vinylpyrrolidone, and vinyl chloride; (meth) acrylates such as methyl (meth) acrylate and lauryl (meth) acrylate; (meth) acrylamide. , Amido-based monomers such as dimethyl (meth) acrylamide; (meth) acrylonitrile and the like.

(Structure and physical properties of polymer)
The polymer may be either (1) a random copolymer or (2) a block copolymer. However, it is preferable that the polymer blocks mainly composed of the constituent units derived from the respective monomers are connected to each other and have a polymer structure in which the functions are shared between the water-soluble portion and the pigment-adsorbed portion. That is, the polymer used as the dispersant is preferably a block copolymer having a polymer block A containing the structural unit (A) and a polymer block B containing the structural unit (B). Further, the polymer is (2-1) AB block copolymer; (2-2) ABA block copolymer; or (2-3) graft copolymer grafted with polymer block A with polymer block B as the main chain. ; Is preferable. The polymer having any of the structures (2-1) to (2-3) has a separate function for each block. Therefore, for example, the polymer block B is strongly adsorbed on the surface of the pigment, and the polymer. When the block A is dissolved in the aqueous medium, the dispersion stability can be further improved while further suppressing the aggregation of the pigment particles due to steric hindrance.

The polystyrene-equivalent number average molecular weight (Mn) of the polymer as measured by gel permeation chromatography (GPC) is 4,000 to 15,000, preferably 4,500 to 14,000, more preferably 5. It is 000 to 13,000. If the Mn of the polymer is less than 4,000, the effect of improving the dispersion stability of the aqueous pigment dispersion may be slightly reduced. On the other hand, if the Mn of the polymer exceeds 15,000, the viscosity of the aqueous pigment dispersion may be excessively increased.

It is preferable that the molecular weights of the polymers are uniform to some extent. Specifically, the PDI (molecular weight distribution = weight average molecular weight (Mw) / number average molecular weight (Mn)) of the polymer is preferably 2.5 or less.

(Polymer manufacturing method)
The polymer used as a dispersant can be produced by a conventionally known polymerization method such as a radical polymerization method or an ionic polymerization method. Of these, production by a radical polymerization method is preferable because the process is simple. In the case of random copolymerization, the monomer and radical generator are heated and stirred, preferably polymerized in a solvent. The AB block copolymer and the AB block copolymer are preferably produced by a living radical polymerization method because the structure can be strictly controlled. Examples of the living radical polymerization method include a method using nitroxide, an atom transfer radical polymerization method, a reversible addition cleavage type chain transfer polymerization method, and a TERP method using organic tellurium as an initiator. Of these, a reversible phase transfer catalyst polymerization method using an iodide as an initiator and an organic compound as a catalyst is preferable because it does not require an organic metal or a special compound.

In the reversible mobile catalyst polymerization method, a radically polymerizable group such as a vinyl group, an acrylic group or a methacrylic group can be used. Of these, the use of a methacrylic group is preferable because the structure can be controlled under relatively mild conditions. That is, it is preferable to use the monomer (A) in which a group containing a methacryloyloxy group or a methacryloylamino group is bonded to one end thereof.

For the graft copolymer in which the polymer block A is grafted with the polymer block B as the main chain, for example, a polymer block A (macromonomer) having a radically polymerizable group at the end thereof is prepared in advance, and the macromonomer and the monomer (B) are prepared in advance. Can be produced by copolymerizing. For macromonomers, for example, after introducing these functional groups at the terminals using a chain transfer agent having a hydroxyl group or a carboxy group, glycidyl (meth) acrylate, (meth) acryloyloxyethyl isocyanate, etc. are used as the functional groups. Can be produced by reacting. A chain transfer agent such as ethyl bromomethylacrylate can also be used.

It is preferable to produce the polymer by solution polymerization in which the polymer can be taken out in a solution state. A water-soluble organic solvent is preferable as the solvent used in the solution polymerization. When solution polymerization is carried out using a water-soluble organic solvent, it can be used as it is as a material for producing an aqueous pigment dispersion without post-treatment after the completion of polymerization. Examples of the water-soluble organic solvent include alcohol solvents such as ethanol and isopropanol; ether solvents such as tetrahydrofuran; glycol solvents such as propylene glycol monomethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, and tripropylene glycol monomethyl ether; N. -Amid solvents such as methylpyrrolidone, 3-methoxy-N, N-dimethylpropionamide, 3-butoxy-N, N-dimethylpropionamide; sulfur solvents such as dimethylsulfoxide; tetramethylurea, dimethylimidazolidinone, etc. Urea-based solvent; etc. can be used. Of these, a glycol-based solvent is preferable because it can improve the wettability to the pigment and promote the dispersion. After solution polymerization, the polymer can be isolated and used by removing the solvent or precipitating it in a poor solvent.

(Pigment)
As the pigment, conventionally known pigments such as yellow, red, blue, green, purple, and black can be used. As pigments, Pigment Yellow 14, 17, 74, 83, 93, 139, 150, 155, 180, 185; Pigment Red 5, 48: 2, 48: 3, 57: 1, 113, 122, 146, 147, 150, 184, 202, 238, 245, 254, 255, 269, 282; Pigment Blue 15, 15: 3, 15: 4, 15: 6, 60; Pigment Violet 19; Pigment Black 7 and the like. These pigments can be used alone or in combination of two or more. Further, a surface-treated pigment obtained by treating these pigments with a pigment treating agent or a pigment derivative can also be used. Among the above pigments, Pigment Red 122, Pigment Violet 19, Pigment Yellow 74, 185, Pigment Blue 15: 3, and Pigment Black 7 are preferable from the viewpoints of hue, saturation, price and the like.

Pigment Yellow 74 is widely used as a yellow pigment. On the other hand, considering the light resistance and the influence on the environment, it is preferable to use the pigment ero 185 represented by the following formula (1) as a substitute for the pigment ero 74. Pigment Yellow 185 is a pigment having low alkali resistance, such as being dissolved under alkaline conditions and turning orange. Further, since the surface of Pigment Yellow 185 is hydrophilic, it has conventionally been a kind of pigment that is difficult to disperse in an aqueous medium by hydrophobic interaction using a dispersant. However, by using the above-mentioned predetermined polymer as a dispersant, even when Pigment Yellow 185 is used at a high concentration, it can be finely dispersed in a good state and an aqueous pigment having excellent storage stability. It can be a dispersion.

When Pigment Yellow 185 is used as a pigment, using a polymer containing a structural unit (B) derived from a monomer (B) having an amino group as a dispersant enhances the dispersibility of the pigment and the storage stability of the dispersion. It is preferable because it can be used. Pigment yellow 185 is considered to have low alkali resistance because the skeleton similar to barbituric acid in its molecular structure is decomposed by a base to form a neutralized salt. On the other hand, when a polymer containing a structural unit (B) derived from a monomer (B) having an amino group is used as a dispersant, the amino group in the polymer forms an ion-neutralized salt structure with pigment ero 185. It is considered that the polymer into which the skeleton of Pigment Yellow 185 is introduced is adsorbed on Pigment Yellow 185 to improve the dispersibility.

The content of the pigment in the aqueous pigment dispersion is preferably 10 to 40% by mass, more preferably 15 to 35% by mass. When the pigment content is more than 40% by mass, the viscosity of the aqueous pigment dispersion liquid increases and the fluidity tends to decrease. For this reason, the production of the aqueous pigment dispersion liquid becomes somewhat difficult, and it may become difficult to handle when producing the emulsion polymerized toner. On the other hand, if the content of the pigment is less than 10% by mass, it is slightly disadvantageous in terms of economy. By using the above-mentioned specific polymer as a dispersant, even Pigment Yellow 185, which has been difficult to disperse until now, can be dispersed at a higher concentration. Therefore, when the pigment is Pigment Yellow 185, the content of the pigment in the aqueous pigment dispersion is preferably 20 to 40% by mass, and more preferably 20 to 30% by mass.

The content of the dispersant in the aqueous pigment dispersion is preferably 5 to 60% by mass, more preferably 10 to 50% by mass, based on the content of the pigment. If the content of the dispersant based on the content of the pigment is less than 5% by mass, it may be difficult to refine the pigment in the process of producing the aqueous pigment dispersion liquid. On the other hand, when the content of the dispersant based on the pigment content is more than 60% by mass, the viscosity of the aqueous pigment dispersion tends to increase excessively, which makes it somewhat difficult to disperse the pigment and is economical. It is a little disadvantageous in terms of.

(Characteristics of aqueous pigment dispersion)
The pH of the aqueous pigment dispersion at 25 ° C. is 3.0 to 8.4. Within this pH range, toner particles can be easily precipitated when producing an emulsion polymerized toner. When a pigment that is easily dissolved or decomposed under alkaline conditions such as Pigment Yellow 185 is used, the aqueous pigment dispersion is preferably in the range of acidic to neutral. More specifically, the pH of the aqueous pigment dispersion is preferably 4.0 to 7.8, and even more preferably 5.0 to 7.5. Generally, in the above pH range, ion repulsion of pigment particles is unlikely to occur, so that the dispersibility may decrease. On the other hand, in the case of the aqueous pigment dispersion liquid of the present invention, since the above-mentioned specific polymer is used as a dispersant, the dispersibility of the pigment is excellent even within the above pH range.

The number average particle size of the pigment contained in the aqueous pigment dispersion in the dispersed state is preferably 80 to 300 nm, and more preferably 100 to 200 nm. When the number average particle size of the pigment is more than 300 nm, the tinting strength, saturation, transparency and the like of the toner may be easily deteriorated. On the other hand, it takes a long time to produce an aqueous pigment dispersion having a number average particle size of pigments of less than 80 nm, which is somewhat disadvantageous in terms of economy. In addition, it may be difficult to control the particle size in the coagulation fixing step when producing the emulsion polymerized toner. The number average particle size of the pigment in the present specification is a number average particle size measured by a light scattering method using a dynamic light scattering type particle size distribution measuring device or the like.

(Manufacturing method of aqueous pigment dispersion)
The aqueous pigment dispersion of the present invention can be produced according to a conventionally known method. For example, a dispersant (polymer), a pigment, and an aqueous medium are mixed, and various additives are further added as needed. If necessary, the pigment is homogenized to some extent with a stirrer, and then dispersed using a disperser until the particle size of the pigment is within the desired range. As a result, the desired aqueous pigment dispersion can be obtained. As the disperser, for example, a conventionally known disperser such as a kneader, an attritor, a ball mill, a sand mill using glass or zircon, a horizontal media disperser, a colloid mill, or a high-pressure homogenizer can be used.

The aqueous pigment dispersion is a water-soluble solvent such as ethylene glycol, propylene glycol, 1,3-butylene glycol, and glycerin in consideration of the wettability, drying property, ejection property, fluidity, viscosity, etc. of the pigment. Water-soluble polymer substances such as methyl cellulose, ethyl cellulose, carboxymethyl cellulose and polyethylene glycol; nonionic surfactants and other known antifoaming agents; and various additives such as preservatives can be appropriately blended.

The content of the above-mentioned various additives in the aqueous pigment dispersion is usually 200% by mass or less, preferably 100% by mass or less, based on the pigment content. If the content of the various additives is more than 200% by mass, the dispersant (polymer) adsorbed on the surface of the pigment may be easily desorbed, and the dispersion stability of the pigment may be easily lowered.

The produced aqueous pigment dispersion can be used as it is, or can be used after removing a small amount of foreign substances and coarse particles using a centrifuge, an ultracentrifuge, a filter or the like. It is preferable to remove foreign substances and coarse particles because the reliability of the aqueous pigment dispersion can be improved. The viscosity of the aqueous pigment dispersion may be arbitrarily set according to the intended use.

The aqueous pigment dispersion of the present invention was mixed with, for example, an emulsion of a binder resin produced by emulsion polymerization, and if necessary, mixed with other materials such as a charge control agent, a magnetic substance, and a wax component. After that, a predetermined operation such as controlling the temperature, adjusting the pH, or adding a salt is performed. As a result, toner particles can be coagulated and fixed to a desired particle size to generate toner particles. Then, the emulsion polymerized toner can be obtained by washing, filtering, drying and the like.

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. In addition, "part" and "%" in Examples and Comparative Examples are based on mass unless otherwise specified.

<Manufacturing of dispersant (polymer)>
(Production Example 1: Random Dispersant-1)
100 parts of polyethylene glycol propylene glycol monomethyl ether monoamine (EOPO-1) was placed in a separable flask equipped with a stirrer, a cooling tube, a thermometer, a nitrogen introduction tube, and a dropping device and stirred. This "EOPO-1" has an oxyethylene unit: oxypropylene unit = 32: 9 (molar ratio converted from NMR), n = 41, and the content of the oxyethylene unit (EO content) is 71. It was 8%, the amine value was 27.6 mgKOH / g, and the average molecular weight calculated from the amine value was 2,031. The EO content of EOPO-1 is the structural formula of EOPO-1 (CH ₃ (OCH ₂ CH ₂ ) _32- (OCH ₂ CHCH ₃ ) _9- NH ₂ , molecular weight = 15 + 44 × 32 + 58 × 9 + 16 = 1,961. ), The molecular weight of the oxyethylene unit (= 1,408) was calculated as the ratio (mass ratio (%)). Hereinafter, the EO content was calculated from the molecular weight in the same manner.

Next, a mixed solution of 7.64 parts of methacryloyloxyethyl isocyanate (MOI) (trade name “Karenzu MOI”, manufactured by Showa Denko KK) and 7.64 parts of tetrahydrofuran (THF) was added dropwise into the flask over 1 hour. After confirming that the isocyanate had disappeared using an infrared spectrophotometer (IR), the amine value was measured by the titration method shown below. As a result, the amine value was almost 0 mgKOH / g, and almost no amino group remained. From the above, it was confirmed that a macromonomer in which a group containing a methacryloylamino group was bonded to one end of polyethylene glycol propylene glycol monomethyl ether was produced.

[Titration method (measurement of amine value)]
0.5 parts of the precisely weighed sample was diluted with 20 parts of a mixed solvent of toluene / ethanol (toluene: ethanol = 3: 2) to homogenize. Bromophenol blue was used as an indicator, and a 0.1 mol / L ethanol hydrochloride solution was titrated as a titration solution, and the amine value (mgKOH / g) was measured and calculated.

Then, 146.7 parts of THF, 8.61 parts of 4-vinylpyridine (4VP), 17.6 parts of butyl methacrylate (BMA), and 1.5 parts of thioglycerol were added for homogenization, and then azobis 2,4. -Dimethylvaleronitrile (V-65) (trade name "V-65", manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.) was further added by 0.1 part and polymerized at 65 ° C. for 8 hours to form a polymer. Got The number average molecular weight (Mn) of the polystyrene-equivalent polymer measured by gel permeation chromatography (GPC) using a 0.1 mmol / L dimethylformamide solution of lithium bromide as a developing solvent by sampling a part of the polymer solution is It was 11,300. The molecular weight distribution (weight average molecular weight (Mw) / number average molecular weight (Mn) = PDI) was 2.05. The macromonomer used was not detected by GPC.

After homogenizing by adding 146.7 parts of water, THF was distilled off under reduced pressure, and water was further added to adjust the solid content of the polymer solution to 40.0%. The pH (25 ° C.) measured by diluting a part of the polymer solution with ion-exchanged water 10-fold was 8.3. The amine value of the polymer was 33.7 mgKOH / g, and the EO content in the polymer was 53.0%. The obtained polymer was designated as "random dispersant-1".

(Production Examples 2-4: Random Dispersant-2-4)
Polymer solutions containing random dispersants-2 to 4 were prepared in the same manner as in Production Example 1 described above, except that the types and amounts of the components shown in Table 1 were used. In Table 1, "EOPO-2" is polyethylene glycol propylene glycol monomethyl ether monoamine, oxyethylene unit: oxypropylene unit = 19: 3 (molar ratio converted from NMR), and the average of oxyethylene oxypropylene units. The number of repetitions n is 22, the content of oxyethylene units (EO content) is 80.3%, the amine value is 55.3 mgKOH / g, and the average molecular weight calculated from the amine value is 1,014. there were.

(Production Example 5: Random Dispersant-5)
100 parts of EOPO-1 was placed in a flask similar to that used in Production Example 1 and stirred. Then, a mixed solution of 7.59 parts of methacrylic anhydride and 7.59 parts of THF was added dropwise to the flask over 1 hour, and then the mixture was reacted by stirring at 50 ° C. for 2 hours. After confirming that the acid anhydride had disappeared using IR, the acid value was measured by the titration method shown below. As a result, the acid value in the system was 23.9 mgKOH / g, and the acid value converted by removing the THF component was 25.6 mgKOH / g. From the above, it was confirmed that a macromonomer in which a group containing a methacryloylamino group was bonded to one end of polyethylene glycol propylene glycol monomethyl ether was produced.

[Titration method (measurement of acid value)]
0.5 parts of the precisely weighed sample was diluted with 20 parts of a mixed solvent of toluene / ethanol (toluene: ethanol = 3: 2) to homogenize. Phenolphthalein was used as an indicator, and a 0.1 mol / L potassium hydroxide ethanol solution was titrated as a titration solution, and the acid value (mgKOH / g) was measured and calculated.

After homogenizing by adding 151.69 parts of THF, 4.23 parts of acrylic acid (AA), 17.6 parts of MMA, and 1.5 parts of thioglycerol, 0.1 part of V-65 was further added to 65 ° C. The polymer was polymerized for 8 hours to form a polymer, and a polymer solution was obtained. The Mn of the polymer was 13,000 and the PDI was 1.98. The macromonomer used was not detected by GPC. After water was added to homogenize, THF was distilled off under reduced pressure, and water was further added to adjust the solid content of the polymer solution to 40.0%. The pH (25 ° C.) measured by diluting a part of the polymer solution with ion-exchanged water 10-fold was 3.6. The acid value of the polymer was 45.3 mgKOH / g, and the EO content in the polymer was 56.8%. The obtained polymer was designated as "Random Dispersant-5".

(Production Example 6: Block Dispersant-1)
185.1 parts of tripropylene glycol monomethyl ether (TPME), 532.0 parts of polyethylene glycol monomethacrylate (PEGMA) (n = 4, EO content 67.1%), in the same flask as that used in Production Example 1. 71.7 parts of BMA, 9.1 parts of iodine, 2,2-azobis (4-methoxy-2,4-dimethylvaleronitrile) (V-70) (trade name "V-70", manufactured by Fuji Film Wako Pure Chemical Industries, Ltd. ) 33.3 parts and 0.5 part of N-iodosuccinate imide were added. After stirring and homogenizing the contents, the temperature was raised to 45 ° C. and polymerization was carried out for 5 hours to form a polymer block A. The Mn of the polymer block A was 8,200 and the PDI was 1.15. The PEGMA used was not detected by GPC. The polymerization rate was about 100%.

Then, 70.7 parts of dimethylaminoethyl methacrylate (DMAEMA) was added and polymerized at 45 ° C. for 8 hours to form a polymer block B to obtain a polymer solution containing a polymer. The Mn of the polymer was 9,300 and the PDI was 1.23. The polymerization rate was about 100%. Water was added to adjust the solid content of the polymer solution to 40.0%. The pH (25 ° C.) of the polymer solution was 8.3. The amine value of the polymer was 37.5 mgKOH / g, and the EO content in the polymer was 52.9%. The obtained polymer (AB block copolymer) was designated as "block dispersant-1".

(Production Example 7: Block Dispersant-2)
In a flask similar to that used in Production Example 1, 120.0 parts of diethylene glycol dimethyl ether (DMDG), 80 parts of polyethylene glycol monomethyl ether acrylate (PEGMEA400) (n = 9, EO content 82.1% by mass), acrylic acid. 25.6 parts of butyl (BA) and 1.6 parts of N-tert-butyl-N- (2-methyl-1-phenylpropyl) -O- (1-phenylethyl) hydroxylamine (manufactured by Sigma Aldrich) I put it in. It was heated to 130 ° C. over 1 hour while flowing nitrogen gas. Then, the reaction system was kept at 130 ° C. and polymerized for 5 hours to form a polymer block A. The Mn of the polymer block A was 8,600, the PDI was 1.23, and the polymerization rate was about 100%.

Then, 12.6 parts of 2-vinylpyridine was added and polymerized for 3 hours to form a polymer block B to obtain a polymer solution containing a polymer. The Mn of the polymer was 11,200 and the PDI was 1.21. The polymerization rate was about 100%. Water was added to adjust the solid content of the polymer solution to 40.0%. The pH (25 ° C.) of the polymer solution was 7.6. The amine value of the polymer was 56.9 mgKOH / g, and the EO content in the polymer was 55.5% by mass. The obtained polymer (AB block copolymer) was designated as "block dispersant-2".

(Production Example 8: Block Dispersant-3)
243.8 parts of diethylene glycol monobutyl ether (BDG), 3.632 parts of ethylene glycol di (2- (2-iodoisobutyryloxy)), 31.4 parts of DMAEMA, in the same flask as that used in Production Example 1. 8.8 parts of BzMA, 1.84 parts of dimethyl 2,2'-azobis (2-methylpropionate) (V-601) (trade name "V-601", manufactured by Fuji Film Wako Pure Chemical Industries, Ltd.), and 0 diphenylmethane. .16 copies were added. The temperature was raised to 85 ° C. and polymerization was carried out for 8 hours to form a polymer block B. The Mn of the polymer block B was 3,400 and the PDI was 1.13. Next, 198.4 parts of polyethylene glycol monomethyl ether methacrylate (PEGMEMA400) (n = 9, EO content 79.8%) was added and polymerized for 8 hours to form polymer blocks A at both ends of polymer block B. , A polymer solution containing a polymer was obtained. The Mn of the polymer was 10,200 and the PDI was 1.46. The polymerization rate was about 100%. Water was added to adjust the solid content of the polymer solution to 40.0%. The pH (25 ° C.) of the polymer solution was 8.4. The amine value of the polymer was 45.0 mgKOH / g, and the EO content in the polymer was 65.4%. The obtained polymer (ABA block copolymer) was designated as "block dispersant- 3 ".

(Production Example 9: Graft Dispersant-1)
In a flask similar to that used in Production Example 1, 187.5 parts of BDG, 7.5 parts of ethyl bromomethylacrylate (EBMA), 108 parts of PEGMEMA400, 12 parts of MMA, and 0.75 parts of V-65 were placed, and the temperature was 70 ° C. Polymerized in 10 hours to form a polymer block A to be a graft chain. The Mn of the polymer block A was 3,200 and the PDI was 1.51. Next, 15 parts of VIm, 15 parts of BzMA, and 3.0 parts of t-butylperoxy-2-ethylhexanoate (trade name "Perbutyl O", manufactured by Nichiyu Co., Ltd.) were added and polymerized at 90 ° C. for 10 hours. , A polymer solution containing a polymer (B-g-A polymer) obtained by grafting the polymer block A onto the polymer block B was obtained. The Mn of the polymer was 5,200 and the PDI was 1.86. Water was added to adjust the solid content of the polymer solution to 40.0%. The pH (25 ° C.) of the polymer solution was 8.0. The amine value of the polymer was 56.0 mgKOH / g, and the EO content in the polymer was 54.7%. The obtained polymer (B-g-A polymer) was designated as "graft dispersant-1".

(Production Example 10: Graft Dispersant-2)
A polymer solution containing a polymer (B-g-A polymer) in which the polymer block A was grafted to the polymer block B was obtained in the same manner as in Production Example 9 described above, except that 4VP was used instead of VIm. The Mn of the polymer block A was 3,000 and the PDI was 1.52. The Mn of the polymer was 6,100 and the PDI was 1.73. The pH (25 ° C.) of the polymer solution was 4.9 and the solid content was 40.0%. The amine value of the polymer was 35.6 mgKOH / g, and the EO content in the polymer was 56.0%. The obtained polymer (B-g-A polymer) was designated as "graft dispersant-2".

(Production Example 11: Graft Dispersant-3)
A polymer block was added to the polymer block B in the same manner as in Production Example 8 described above, except that methacrylic acid (MA) was used instead of VIm and 2-ethylhexyl acrylate (EHA) was used instead of BzMA. A polymer solution containing a polymer grafted with A (B-g-A polymer) was obtained. The Mn of the polymer block A was 3,200 and the PDI was 1.49. The Mn of the polymer was 5,700 and the PDI was 1.93. The pH (25 ° C.) of the polymer solution was 4.6 and the solid content was 40.0%. The acid value of the polymer was 62.1 mgKOH / g, and the EO content in the polymer was 56.0%. The obtained polymer (B-g-A polymer) was designated as "graft dispersant-3".

(Comparative Production Example 1: Random Comparative Dispersant-1)
A polymer solution containing a polymer was obtained in the same manner as in Production Example 1 described above, except that 4VP was not used and the amount of BMA was increased accordingly. The Mn of the polymer was 12,300 and the PDI was 2.01. The pH (25 ° C.) of the polymer solution was 7.8 and the solid content was 40.0%. The amine value of the polymer was 0 mgKOH / g, and the EO content in the polymer was 53.0%. The obtained polymer was designated as "Random Comparative Dispersant-1".

(Comparative Production Example 2: Random Comparative Dispersant-2)
The polymer was the same as in Production Example 1 described above, except that the amount of EOPO-1 was 70 parts, the amount of MOI was 5.34 parts, and the amount of BMA was 49.9 parts. A polymer solution containing the above was obtained. The Mn of the polymer was 14,300 and the PDI was 2.30. The pH (25 ° C.) of the polymer solution was 8.4 and the solid content was 40.2%. The amine value of the polymer was 33.7 mgKOH / g, and the EO content in the polymer was 37.8%. The obtained polymer was designated as "Random Comparative Dispersant-2".

(Comparative Production Example 3: Block Comparative Dispersant)
A polymer solution containing a polymer was prepared in the same manner as in Production Example 6 above, except that polyethylene glycol monomethyl ether monomethacrylate (PEGMEMA1000) (n = 23, EO content 91.0%) was used instead of PEGMA. Obtained. The Mn of the polymer block A was 7,300 and the PDI was 1.14. The Mn of the polymer was 8,300 and the PDI was 1.34. The pH (25 ° C.) of the polymer solution was 8.3 and the solid content was 40.0%. The amine value of the polymer was 37.6 mgKOH / g, and the EO content in the polymer was 71.0%. The obtained polymer (AB block copolymer) was designated as a "block comparative dispersant".

(Comparative Production Example 4: Graft Comparative Dispersant-1)
A polymer in which polymer block A is grafted to polymer block B in the same manner as in Production Example 9 described above, except that the amount of t-butylperoxy-2-ethylhexanoate (perbutyl O) is 0.5 parts. A polymer solution containing (B-g-A polymer) was obtained. The Mn of the polymer was 16,300 and the PDI was 2.39. The pH (25 ° C.) of the polymer solution was 4.6 and the solid content was 40.0%. The acid value of the polymer was 61.8 mgKOH / g, and the EO content in the polymer was 56.0%. The obtained polymer (B-g-A polymer) was designated as "graft comparative dispersant-1".

(Comparative Production Example 5: Graft Comparative Dispersant-2)
After completion of the polymerization, the polymer block was formed in the same manner as in Production Example 9 described above, except that methacrylic acid and this molar aqueous sodium hydroxide solution were added to neutralize the carboxy group derived from methacrylic acid to obtain a sodium salt. A polymer solution containing a polymer (B-g-A polymer) in which polymer block A was grafted to B was obtained. The Mn of the polymer before neutralization was 4,400 and the PDI was 1.78. The pH (25 ° C.) of the polymer solution was 9.8 and the solid content was 40.0%. The acid value of the polymer was 62.1 mgKOH / g, and the EO content in the polymer was 56.0%. The obtained polymer (B-g-A polymer) was designated as "graft comparative dispersant-2".

<Manufacturing of aqueous pigment dispersion (1)>
( Reference Examples 1 to 4)
Each component shown in Table 2 was put into a horizontal bead mill filled with 0.1 mm zirconia beads and dispersed. Then, it was sequentially filtered through a 1 μm membrane filter and a 0.5 μm membrane filter to obtain an aqueous pigment dispersion of each color. The pH, viscosity (mPa · s), and number average particle size (nm) of the obtained aqueous pigment dispersion at 25 ° C. were measured. The viscosity was measured using a BL type viscometer under the condition of a rotation speed of 60 rpm. The number average particle size of the pigment was measured using a dynamic light scattering type particle size distribution measuring device (trade name "NICOMP380ZLS-S", manufactured by PS Japan Co., Ltd.). Further, the pH, viscosity (mPa · s), and number average particle size (nm) of the pigment were measured at 25 ° C. after storing the obtained aqueous pigment dispersion at 50 ° C. for 1 week. The results are shown in Table 2.

( Reference Examples 5 and 6, Examples 7 to 10)
An aqueous pigment dispersion was obtained in the same manner as in Reference Examples 1 to 4 described above, except that the formulations shown in Table 3 were used. The pH, viscosity (mPa · s), and number average particle size (nm) of the obtained aqueous pigment dispersion at 25 ° C. were measured. Further, the pH, viscosity (mPa · s), and number average particle size (nm) of the pigment were measured at 25 ° C. after storing the obtained aqueous pigment dispersion at 50 ° C. for 1 week. The results are shown in Table 3.

(Comparative Examples 1 to 4)
An aqueous pigment dispersion was obtained in the same manner as in Reference Examples 1 to 4 described above, except that the formulations shown in Table 4 were used. The pH, viscosity (mPa · s), and number average particle size (nm) of the obtained aqueous pigment dispersion at 25 ° C. were measured. Further, the pH, viscosity (mPa · s), and number average particle size (nm) of the pigment were measured at 25 ° C. after storing the obtained aqueous pigment dispersion at 50 ° C. for 1 week. The results are shown in Table 4. The comparative aqueous cyan dispersion -3 of Comparative Example 3 became a gel, and the viscosity and the number average particle size of the pigment could not be measured.

<Manufacturing of binder emulsion for emulsion polymerization toner>
(Manufacturing Example 12)
100 parts of water was placed in a flask similar to that used in Production Example 1, and nitrogen gas was blown into the flask for 30 minutes. Put 76 parts of styrene, 20 parts of butyl acrylate, 4 parts of acrylic acid, and 3 parts of polyethylene glycol glycol alkenyl ether (trade name "Latemuru PD-420", manufactured by Kao Corporation, HLB 12.6) in a separate container and mix them. A uniform monomer mixed solution was obtained. The obtained monomer mixture solution was placed in a dropping funnel. The inside of the flask was heated to 60 ° C., 0.8 part of potassium persulfate was added, and then the monomer mixture solution was added dropwise over 3 hours. After completion of the dropping, the mixture was aged at 60 ° C. for 10 hours to obtain an emulsion (binder emulsion) containing a toner binder resin having a glass transition temperature of about 54 ° C. The solid content of the obtained binder emulsion was 50.6% and the pH was 5.6. The average particle size of the particles in the binder emulsion was 200 nm.

<Manufacturing of Emulsion Polymerized Toner (1)>
(Application Experiment Example 1)
100 parts of the binder emulsion and 5.5 parts of the aqueous cyan dispersion solution-1 (in terms of pigment content) were mixed to obtain a mixed solution. The obtained mixed solution was heated to 80 ° C. and held for 2 hours, and then heated at 90 ° C. for 3 hours to mature the agglomerated particles. After cooling, the agglomerates were filtered, washed with ion-exchanged water, and then dried to obtain cyan toner-1, which is an emulsion polymerization toner.

(Applied Experimental Examples 2-4, Applied Experimental Examples-Comparison 1, Comparison 2)
In the same manner as in Applied Experimental Example 1 described above, except that the aqueous pigment dispersions shown in Table 5 were used instead of the aqueous cyan dispersion-1, the emulsified polymerized toners, erotonner-1 and magenta toner-1. , Black Toner-1, Cyan Toner-2, and Cyan Toner-3 were obtained.

<Evaluation of Emulsion Polymerized Toner (1)>
(Pigment yield)
The degree of coloring of the filtrate generated in the process of producing the emulsion-polymerized toner was observed, and the yield of the pigment (pigment usage rate) was evaluated according to the evaluation criteria shown below. The results are shown in Table 5.
◯: Transparent Δ: Lightly colored ×: Colored in the same manner as the aqueous pigment dispersion used

(Ratio of fine particles and coarse particles)
The volume average particle size (DV50 (μm)) of the emulsion polymerization toner was measured using a particle size distribution measuring machine (trade name “Coulter Counter Multisizer II”, manufactured by Beckman Coulter). The results are shown in Table 5. In addition, the ratio of fine particles (3 μm or less) and the ratio of coarse particles (15 μm or more) were calculated, and the ratio of fine particles and coarse particles was evaluated according to the evaluation criteria shown below. The results are shown in Table 5.
◯: 1% or less Δ: 1% or more 3% or less ×: 3% or more

Emulsion-polymerized toners were produced using the cyan-colored aqueous pigment dispersions obtained in Reference Examples 5 and 6 and Examples 7 to 9, respectively, and the same evaluation as above was performed. As a result, an emulsion-polymerized toner having a small proportion of fine particles and coarse particles could be produced with good pigment yield.

<Manufacturing of aqueous pigment dispersion (2)>
( Reference Examples 11 , 12, 15, Examples 13, 14, 16)
Aqueous pigment dispersions (aqueous yellow dispersions-2 to 7) were obtained in the same manner as in Reference Examples 1 to 4 described above, except that the formulations shown in Table 6 were used. As the pigment, Pigment Yellow 185 (PY-185) (trade name "Pariotol Yellow D-1155", manufactured by BASF) was used. The pH, viscosity (mPa · s), and number average particle size (nm) of the obtained aqueous pigment dispersion at 25 ° C. were measured. Further, the pH, viscosity (mPa · s), and number average particle size (nm) of the pigment were measured at 25 ° C. after storing the obtained aqueous pigment dispersion at 50 ° C. for 1 week. The results are shown in Table 6.

(Comparative Examples 5 to 8)
An aqueous pigment dispersion (Comparative Aqueous Yellow Dispersion-1 to 4) was obtained in the same manner as in Reference Examples 1 to 4 described above except that the formulations shown in Table 7 were used. As the pigment, Pigment Yellow 185 (PY-185) (trade name "Pariotol Yellow D-1155", manufactured by BASF) was used. The pH, viscosity (mPa · s), and number average particle size (nm) of the obtained aqueous pigment dispersion at 25 ° C. were measured. Further, the pH, viscosity (mPa · s), and number average particle size (nm) of the pigment were measured at 25 ° C. after storing the obtained aqueous pigment dispersion at 50 ° C. for 1 week. The results are shown in Table 7.

<Manufacturing of emulsion polymerized toner (2)>
[Applied Experimental Examples 5-9, Applied Experimental Examples-Comparison 3, Comparison 4]
An emulsion polymerized toner was obtained in the same manner as in Applied Experimental Example 1 described above, except that the aqueous yellow dispersions shown in Table 8 were used instead of the aqueous cyan dispersion-1.

<Evaluation of emulsion polymerized toner (2)>
In the same manner as in the above-mentioned "evaluation of emulsion polymerized toner (1)", the yield of the pigment (the usage rate of the pigment) and the ratio of the fine particles and the coarse particles were evaluated. The results are shown in Table 8.

The emulsion-polymerized toner was produced by a method of adding a salt and precipitating instead of the above-mentioned production method using a cloud point, and the same evaluation as described above was performed. As a result, when the aqueous pigment dispersion of the present embodiment was used, an emulsion-polymerized toner having a small proportion of fine particles and coarse particles could be produced with good pigment yield.

When the aqueous pigment dispersion of the present invention is used in the production of an emulsion polymerization toner, the pigment can be efficiently introduced into the toner, so that the yield of the pigment can be improved. In addition, since it is possible to obtain a toner having a low content of fine particles and coarse particles, it is possible to improve the yield of toner production, and it is possible to obtain effects such as cost reduction, as well as environmental load and energy. It can contribute to the reduction. The pigment dispersion of the present invention is useful as a material for producing, for example, toner for a copying machine.

Claims (7)

An aqueous pigment dispersion containing a pigment, a dispersant for dispersing the pigment, and an aqueous medium containing water.
The dispersant is derived from the monomer (A) in which a group containing a (meth) acryloyloxy group or a (meth) acryloylamino group is bonded to one end of any of the following molecular chains (i) to (iii). A polymer comprising a unit (A) and a structural unit (B) derived from a monomer (B) having a carboxy group or an amino group.
The content of the oxyethylene unit derived from the monomer (A) in the polymer is 50 to 90% by mass based on the total mass of the polymer.
(2-1) AB block copolymer, (2-2), wherein the polymer has (2) a polymer block A containing the structural unit (A) and a polymer block B containing the structural unit (B). ) ABA block copolymer, or (2-3) a graft copolymer obtained by grafting the polymer block A with the polymer block B as the main chain.
The polystyrene-equivalent number average molecular weight of the polymer measured by gel permeation chromatography is 4,000 to 15,000.
The polymer is contained in a substantially unionized state.
An aqueous pigment dispersion having a pH of 3.0 to 8.4.
(I) Polyethylene glycol chain having an average number of repetitions n of oxyethylene units of 4 to 20 (ii) Polyethylene glycol monoalkyl (carbon number 1 to 18) ether chain having an average number of repetitions n of 4 to 9 of oxyethylene units (Iii) Oxyethylene The molecular chain R-represented by the following general formula (1), in which the average number of repetitions n of the oxyethylene oxypropylene unit is 20 to 50 and the content of the oxyethylene unit is 70 to 92% by mass. (OEt) _x- (OPr) _y- A ... (1)
(In the general formula (1), R represents an alkyl group having 1 to 18 carbon atoms, A represents OH or NH ₂ , Et represents an ethylene group, Pr represents a propylene group, and x + y = n. ) The aqueous pigment dispersion according to claim 1, which is a pigment dispersion for an emulsion polymerization toner. The monomer (B) is at least one selected from the group consisting of (meth) acrylic acid or vinylpyridine, vinylimidazole, and dimethylaminoethyl (meth) acrylic acid.
The aqueous pigment dispersion according to claim 1 or 2 , wherein the content of the structural unit (B) in the polymer is 3 to 15% by mass based on the total mass of the polymer. The pigment is a yellow pigment containing Pigment Yellow 185.
The aqueous pigment dispersion according to any one of claims 1 to 3 , wherein the monomer (B) is a monomer having an amino group. The aqueous pigment dispersion according to any one of claims 1 to 4 , wherein the number average particle size of the pigment measured by a light scattering method is 80 to 300 nm. The content of the pigment is 10 to 40% by mass,
The aqueous pigment dispersion according to any one of claims 1 to 5 , wherein the content of the dispersant is 5 to 60% by mass based on the content of the pigment. The pigment is Pigment Yellow 185.
The aqueous pigment dispersion according to any one of claims 1 to 6 , wherein the content of the pigment is 20 to 40% by mass.