Method for producing resin particle dispersion, method for producing toner for developing electrostatic images, and toner for developing electrostatic images

Abstract

To provide a method for producing a resin particle dispersion which suppresses the generation of coarse particles and fine particles.SOLUTION: There is provided a method for producing a resin particle dispersion which comprises a step of adding a neutralizer into a resin-dissolved solution in which a resin having an acid value is dissolved in an organic solvent to neutralize the resin, followed by subjecting the resin to phase inversion emulsification by adding an aqueous medium to obtain a phase inversion emulsified liquid and a step of removing the organic solvent from the phase inversion emulsified liquid, wherein in the step of obtaining the phase inversion emulsified liquid, when the resin-dissolved solution after adding the aqueous medium is stirred and subjected to phase inversion emulsification, the maximum stirring power value per unit resin mass (kg) is 0.4 W or more and 20 W or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a resin particle dispersion for a toner, a method for producing a toner for developing an electrostatic image, and a toner for developing an electrostatic image. [Background technology]

[0002] For example, Patent Document 1 discloses "a method for producing a dispersion of resin particles having acid groups using a phase inversion emulsification method, comprising the following steps: step 1: mixing a resin having acid groups with an organic solvent to prepare a solution; step 2: adding a neutralizing agent to the solution obtained in step 1 and mixing to obtain a neutralized mixed solution having a viscosity of 100 to 1000 mPa·s; step 3: after confirming the viscosity of the neutralized mixed solution obtained in step 2, adding water at an addition rate of 0.5 to 50 parts by mass / minute per 100 parts by mass of the resin having acid groups to obtain an emulsion of resin particles having acid groups; and step 4: removing the organic solvent from the emulsion obtained in step 3 to obtain a dispersion of resin particles having acid groups."

[0003] Furthermore, Patent Document 2 describes a "method for producing a polyester latex dispersion using a phase inversion emulsification method, including the following steps: Step 1: mixing a polyester resin with an organic solvent to prepare a solution 13; Step 2: mixing a neutralizer (1) 14 into the solution 13 obtained in Step 1 in an amount such that the liquid viscosity is in the range of 5 to 500 mPa·s; Step 3: checking the state of the solution 15 obtained in Step 2, determining the amount of neutralizer (2) 16 to be added such that the liquid viscosity is in the range of 50 to 1000 mPa·s, and adding and mixing the neutralizer (2) 16 at least once; Step 4: continuously adding pure water 18 to the solution 17 obtained in Step 3 to form resin particles, thereby obtaining a resin particle dispersion 19; Step 5: removing the organic solvent 12 from the resin particle dispersion 19 obtained in Step 4." " has been disclosed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-193493 [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-131544 Summary of the Invention [Problem to be solved by the invention]

[0005] The object of the present invention is to provide a method for producing a resin particle dispersion, which includes the steps of adding a neutralizing agent to a resin solution obtained by dissolving a resin having an acid value in an organic solvent to neutralize the resin, and then adding an aqueous medium to phase-invert emulsify the resin to obtain a phase-inverted emulsion, and removing the organic solvent from the phase-inverted emulsion, in which, in the step of obtaining a phase-inverted emulsion, the resin solution after adding the aqueous medium is stirred to perform phase-inverted emulsification, and the method suppresses the generation of coarse particles and fine particles compared to when the maximum stirring power value per unit resin mass (kg) is less than 0.4 W or more than 20 W. [Means for solving the problem]

[0006] Specific means for solving the above problems include the following aspects. <1> a step of adding a neutralizing agent to a resin solution obtained by dissolving a resin having an acid value in an organic solvent to neutralize the resin, and then adding an aqueous medium to phase-invert emulsify the resin to obtain a phase-inverted emulsion; removing the organic solvent from the phase inversion emulsion; and A method for producing a resin particle dispersion, wherein in the step of obtaining the phase inversion emulsion, when the resin solution after adding the aqueous medium is stirred to cause phase inversion emulsification, the maximum stirring power value is 0.4 W or more and 20 W or less per unit resin mass (kg). <2> The acid value of the resin is 8 mgKOH / g or more and 20 mgKOH / g or less. <1> 1. A method for producing a resin particle dispersion liquid according to claim 1. <3> The resin is a polyester resin. <1> or <2> 1. A method for producing a resin particle dispersion liquid according to claim 1. <4> the organic solvent contains one or more selected from ketones and one or more selected from alcohols, The amount of the ketones relative to 10 parts by mass of the resin is 4 parts by mass or more and 15 parts by mass or less, and the amount of the alcohols relative to 10 parts by mass of the resin is 1 part by mass or more and 5 parts by mass or less. <1> ~ <3> 10. The method for producing the resin particle dispersion liquid according to claim 9, wherein the resin particle dispersion liquid is a dispersion liquid containing 10% or more of the resin particle dispersion liquid. <5> The ketone is methyl ethyl ketone, and the alcohol is isopropanol. <4> 1. A method for producing a resin particle dispersion liquid according to claim 1. <6> the neutralizing agent is ammonia, The total amount of the neutralizing agent added is 0.02 parts by mass or more and 0.06 parts by mass or less per 10 parts by mass of the resin. <1> ~ <5> 10. The method for producing the resin particle dispersion liquid according to claim 9, wherein the resin particle dispersion liquid is a dispersion liquid containing 10% or more of the resin particle dispersion liquid. <7> The temperature of the resin solution after adding the aqueous medium when undergoing phase inversion emulsification is 20°C or higher and 80°C or lower. <1> ~ <6> 10. The method for producing the resin particle dispersion liquid according to claim 9, wherein the resin particle dispersion liquid is a dispersion liquid containing 10% or more of the resin particle dispersion liquid. <8> The aqueous medium is continuously added to the resin solution, and the rate of addition of the aqueous medium relative to 10 parts by mass of the resin is 0.03 parts by mass / min or more and 0.80 parts by mass / min or less. <1> ~ <7> 10. The method for producing the resin particle dispersion liquid according to claim 9, wherein the resin particle dispersion liquid is a dispersion liquid containing 10% or more of the resin particle dispersion liquid. <9> The phase inversion emulsification of the resin is carried out in an emulsification tank equipped with an anchor agitator, The ratio Di / Dt of the blade diameter Di of the anchor stirring blade to the tank diameter Dt of the emulsification tank is 0.90 or more and 0.99 or less, The rotation speed of the anchor stirring blade is 10 rpm or more and 100 rpm or less. <1> ~ <8> 10. The method for producing the resin particle dispersion liquid according to claim 9, wherein the resin particle dispersion liquid is a dispersion liquid containing 10% or more of the resin particle dispersion liquid. <10> Manufacture of resin particle dispersion for toner <1> ~ <9> 10. The method for producing the resin particle dispersion liquid according to claim 9, wherein the resin particle dispersion liquid is a dispersion liquid containing 10% or more of the resin particle dispersion liquid. <11> <1> ~ <10> a step of aggregating at least the resin particles in a dispersion containing resin particles obtained by the method for producing a resin particle dispersion according to any one of the above items to form aggregated particles; a step of heating the aggregated particle dispersion in which the aggregated particles are dispersed to fuse and coalesce the aggregated particles to form toner particles; A method for producing a toner for developing electrostatic images, comprising: <12> <11> 1. A toner for developing electrostatic images, comprising toner particles obtained by the method for producing a toner for developing electrostatic images according to claim 1. [Effects of the Invention]

[0007] <1> , or <10> According to the present invention, there is provided a method for producing a resin particle dispersion, which includes the steps of adding a neutralizing agent to a resin solution in which a resin having an acid value is dissolved in an organic solvent to neutralize the resin, and then adding an aqueous medium to phase-invert emulsify the resin to obtain a phase-inverted emulsion, and removing the organic solvent from the phase-inverted emulsion. In this method, when the resin solution after adding the aqueous medium is stirred to phase-invert emulsify, the generation of coarse particles and fine particles is suppressed compared to when the maximum stirring power value per unit resin mass (kg) is less than 0.4 W or more than 20 W.

[0008] <2> , or <3> According to the present invention, a method for producing a resin particle dispersion is provided that suppresses the generation of coarse particles and fine particles compared to when the acid value of the resin is less than 8 mgKOH / g or more than 20 mgKOH / g.

[0009] <4> , or <5> According to the invention, a method for producing a resin particle dispersion liquid is provided that suppresses the generation of coarse particles and fine particles compared to when a single organic solvent is used.

[0010] <6> According to the invention relating to the present invention, a method for producing a resin particle dispersion liquid is provided that suppresses the generation of coarse particles and fine particles compared to when the total amount of neutralizing agent added is less than 0.02 parts by mass or more than 0.06 parts by mass per 10 parts by mass of resin.

[0011] <7> According to the invention relating to the above, a method for producing a resin particle dispersion liquid is provided that suppresses the generation of coarse particles and fine particles compared to when the liquid temperature when the resin solution after adding an aqueous medium is subjected to phase inversion emulsification is less than 20°C or more than 80°C.

[0012] <8> According to the invention relating to the present invention, a method for producing a resin particle dispersion liquid is provided in which the addition rate of the aqueous medium per 10 parts by mass of resin is less than 0.03 parts by mass / min or more than 0.80 parts by mass / min, thereby suppressing the generation of coarse particles and fine particles.

[0013] A method for producing a resin particle dispersion is provided that suppresses the generation of coarse particles and fine particles compared to when the ratio Di / Dt of the blade diameter Di of the anchor stirring blade to the vessel diameter Dt of the emulsification vessel is less than 0.90 or more than 0.99, or when the rotation speed of the anchor stirring blade is less than 10 rpm or more than 100 rpm.

[0014] <11> , or <12> According to the invention, a method for producing a resin particle dispersion liquid, which includes a step of adding a neutralizing agent to a resin solution obtained by dissolving a resin having an acid value in an organic solvent to neutralize the resin, and then adding an aqueous medium to phase-invert emulsify the resin to obtain a phase-inverted emulsion, and a step of removing the organic solvent from the phase-inverted emulsion, is provided, in which the method for producing a toner for developing electrostatic images, or a toner for developing electrostatic images, suppresses the occurrence of uneven image density compared to when a method for producing a resin particle dispersion liquid is used in which, in the step of obtaining the phase-inverted emulsion, the resin solution after adding the aqueous medium is stirred to perform phase-inverted emulsification, and a maximum stirring power value is less than 0.4 W or more than 20 W per unit resin mass (kg). [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram illustrating an example of an emulsification tank with agitating blades that is preferably used in a method for producing a resin particle dispersion according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] The following describes an embodiment of the present invention, which is an example. These descriptions and examples are intended to illustrate the present invention, but are not intended to limit the present invention.

[0017] In this specification, a numerical range indicated using "to" indicates a range that includes the numerical values before and after "to" as the minimum and maximum values, respectively. In the present specification, the upper or lower limit of one numerical range may be replaced by the upper or lower limit of another numerical range. In addition, in the numerical ranges described in this disclosure, the upper or lower limit of the numerical range may be replaced by the values shown in the examples.

[0018] In this specification, the term "process" includes not only an independent process but also a process that cannot be clearly distinguished from other processes, as long as the intended purpose of the process is achieved.

[0019] When embodiments are described in this specification with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. Furthermore, the sizes of the components in each drawing are conceptual, and the relative size relationships between the components are not limited to these.

[0020] In this specification, each component may contain multiple corresponding substances. When referring to the amount of each component in a composition in this disclosure, if multiple substances corresponding to each component are present in the composition, the total amount of the multiple substances present in the composition is meant unless otherwise specified.

[0021] In this specification, "toner for developing electrostatic images" is also simply referred to as "toner."

[0022] <Method of manufacturing resin particle dispersion> The method for producing a resin particle dispersion according to this embodiment includes the steps of: adding a neutralizing agent to a resin solution in which a resin having an acid value is dissolved in an organic solvent to neutralize the resin; then adding an aqueous medium to phase-invert emulsify the resin to obtain a phase-invert emulsion; and removing the organic solvent from the phase-invert emulsion. In the step of obtaining a phase inversion emulsion, when the resin solution after adding the aqueous medium is stirred to cause phase inversion emulsification, the maximum stirring power value per unit resin mass (kg) is 0.4 W or more and 20 W or less.

[0023] The method for producing a resin particle dispersion according to this embodiment suppresses the generation of coarse particles and fine particles, and the reason for this is presumed to be as follows.

[0024] As an example, a resin particle dispersion is prepared by dissolving a resin in an organic solvent, neutralizing the resin, mixing it with water to emulsify it by phase inversion, thereby finely dispersing the resin in an aqueous medium, and then removing the organic solvent by distillation under reduced pressure.

[0025] However, during the production process of a resin particle dispersion, coarse particles and fine particles may be generated. One possible cause is that the phase inversion is unevenly distributed due to insufficient stirring of the phase inversion emulsion during phase inversion emulsification, resulting in the generation of coarse particles and fine particles. Another possible cause is that the phase inversion emulsion is subjected to excessive stirring shear force during phase inversion emulsification, resulting in the generation of fine particles.

[0026] In contrast, in the method for producing a resin particle dispersion according to this embodiment, the maximum stirring power value during phase inversion emulsification is set to 0.4 W or more and 20 W or less per unit resin mass (kg).

[0027] Here, the stirring power is the power actually applied to the phase inversion emulsion, and the stirring power value is the value obtained by subtracting the air power (the stirring motor power value when the emulsification tank is empty and the stirring blades are rotated at the same rotation speed) from the stirring motor power value that rotates the stirring blades during phase inversion emulsification. During the phase inversion emulsification process, the stirring power gradually increases from the start of phase inversion emulsification, reaches a peak when phase inversion emulsification is achieved, and then gradually decreases, following a profile.

[0028] Therefore, if the maximum stirring power value (i.e., stirring power value) during phase inversion emulsification is set to 20 W or less, excessive stirring shear force is prevented from being applied to the phase inversion emulsion, and the generation of fine particles is suppressed. On the other hand, if the maximum stirring power value (i.e., stirring power value) during phase inversion emulsification is set to 0.4 W or more per unit resin mass (kg), phase inversion uneven distribution due to insufficient stirring of the phase inversion emulsion is suppressed, and the generation of coarse particles and fine particles is inhibited.

[0029] From the above, it is presumed that the method for producing a resin particle dispersion according to this embodiment suppresses the generation of coarse particles and fine particles.

[0030] Here, the toner produced by the emulsion aggregation method acquires low-temperature fixability by adding a crystalline resin and a release agent, which are low-melting temperature components, to the inside of the toner from the viewpoint of energy saving and productivity. On the other hand, when low melting temperature components are exposed to the surface of toner particles, they deteriorate heat-resistant storage properties and cause image unevenness (image unevenness caused by reduced transfer efficiency due to embedded external additives), especially under high temperature and high humidity conditions. In a toner manufacturing method using an emulsion aggregation method, in order to prevent low melting temperature components from being exposed on the surface of the toner particles, it is preferable to form a shell layer on the outside of the core particles containing the low melting temperature components. However, if coarse particles and fine particles are present in the resin particle dispersion liquid that forms the shell layer, the aggregation balance of the resin particles is lost, making it difficult to prevent low melting temperature components from being exposed on the toner particle surface. In contrast, the resin particle dispersion obtained by the method for producing a resin particle dispersion according to the present embodiment suppresses the generation of coarse particles and fine particles, and therefore, when a shell layer is formed, exposure of low melting temperature components to the toner particle surface is suppressed, resulting in a toner that suppresses image unevenness.

[0031] The method for producing a resin particle dispersion according to this embodiment will be described in detail below.

[0032] (Phase inversion emulsion preparation process) In the phase inversion emulsion preparation process, a neutralizing agent is added to a resin solution in which a resin having an acid value is dissolved in an organic solvent to neutralize the resin, and then an aqueous medium is added to phase invert emulsify the resin and obtain a phase inversion emulsion.

[0033] The phase inversion emulsification method involves adding an aqueous medium (i.e., a W phase) to an oil phase dispersion (i.e., a resin solution that becomes an O phase), in which the resin is dissolved in an organic solvent in which the resin is soluble, to form a continuous phase, thereby converting the resin from W / O to O / W (a so-called phase inversion), turning the oil phase dispersion into a discontinuous phase and dispersing the resin in particulate form in the aqueous medium.

[0034] The phase inversion emulsion is produced, for example, by a known emulsifying apparatus such as an emulsifying tank equipped with an agitating blade. When dissolving a resin in an organic solvent, an aqueous medium and a neutralizing agent may be mixed in addition to the resin and the organic solvent. There are no particular restrictions on the order in which the resin and organic solvent are added to the emulsification tank. However, if the resin is easily soluble in the organic solvent, it is preferable from the viewpoint of dissolution time to add the resin after adding all or part of the organic solvent. The piping for feeding the resin into the emulsification tank can be freely selected depending on the crushed diameter of the resin to be fed, etc. For example, a piping that rises and falls to the bottom of the emulsification tank may be used to prevent dust from flying when the resin is fed. There are no particular restrictions on the position, number, or shape of the nozzles used to add water to a resin solution obtained by dissolving a resin in an organic solvent. For example, the nozzles may be submerged in the liquid. In the case of large-scale equipment, it is preferable to add water from two or more multiple pipes or to use a shower-type nozzle head so that the water is dispersed over the liquid surface from the top of the emulsification tank.

[0035] In phase inversion emulsification, when the resin solution after adding the aqueous medium is stirred to cause phase inversion emulsification, the maximum stirring power value is 0.4 W or more and 20 W or less per unit resin mass (kg), but from the viewpoint of suppressing the generation of coarse particles and fine particles, it is preferably 1 W or more and 12 W or less.

[0036] The liquid temperature when the resin solution after adding the aqueous medium is subjected to phase inversion emulsification is preferably 20°C or higher and 80°C or lower, more preferably 35°C or higher and 65°C or lower, from the viewpoint of suppressing the generation of coarse particles and fine particles.

[0037] The aqueous medium may be added intermittently to the resin solution, but is preferably added continuously. The rate of addition of the aqueous medium per 10 parts by mass of resin is preferably 0.03 parts by mass / min or more and 0.80 parts by mass / min or less, and more preferably 0.1 parts by mass / min or more and 0.40 parts by mass / min or less, from the viewpoint of suppressing the generation of coarse particles and fine particles.

[0038] In the phase inversion emulsification, the stirring blade is not particularly limited, but anchor stirring blades are preferred from the viewpoint of suppressing the generation of coarse particles and fine particles. The ratio Di / Dt (see FIG. 1) of the blade diameter Di of the anchor impeller to the vessel diameter Dt of the emulsification vessel is preferably 0.90 or more and 0.99 or less, more preferably 0.94 or more and 0.99 or less, from the viewpoint of suppressing the generation of coarse particles and fine particles. The rotation speed of the anchor stirring blade is preferably 10 rpm or more and 100 rpm or less, more preferably 20 rpm or more and 80 rpm or less, from the viewpoint of suppressing the generation of coarse particles and fine particles.

[0039] Here, the blade diameter Di of the anchor impeller means the maximum diameter of the path of the impeller when it rotates. In FIG. 1, T indicates the emulsification tank and S indicates the anchor agitator.

[0040] -resin- The resin used is a resin having an acid value, and is preferably a resin having a polar group such as a carboxyl group, a sulfonic acid group, or a hydroxyl group. The resin may be any resin capable of undergoing phase inversion emulsification. Examples of the resin include vinyl resins made of homopolymers of monomers such as styrenes (e.g., styrene, parachlorostyrene, α-methylstyrene, etc.), (meth)acrylic acid esters (e.g., methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (e.g., acrylonitrile, methacrylonitrile, etc.), vinyl ethers (e.g., vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), and olefins (e.g., ethylene, propylene, butadiene, etc.), or copolymers of two or more of these monomers. Examples of the resin include non-vinyl resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and modified rosin, mixtures of these with the vinyl resins, and graft polymers obtained by polymerizing vinyl monomers in the presence of these. These resins may be used alone or in combination of two or more.

[0041] The resin is preferably an amorphous resin, although a crystalline resin (such as a crystalline polyester resin) may also be used. Here, the term "amorphous resin" refers to a resin that, in thermal analysis measurement using differential scanning calorimetry (DSC), does not show a clear endothermic peak but only a stepwise endothermic change, is solid at room temperature, and becomes thermoplastic at a temperature equal to or higher than the glass transition temperature. On the other hand, a crystalline resin is one that shows a clear endothermic peak rather than a stepwise change in endothermic amount in differential scanning calorimetry (DSC). Specifically, for example, a crystalline resin means a resin whose half-width of the endothermic peak when measured at a heating rate of 10°C / min is within 10°C, and an amorphous resin means a resin whose half-width exceeds 10°C or a resin in which no clear endothermic peak is observed.

[0042] The amorphous resin will be described. Examples of amorphous resins include known amorphous resins such as amorphous polyester resins, amorphous vinyl resins (e.g., styrene-acrylic resins), epoxy resins, polycarbonate resins, polyurethane resins, etc. Among these, amorphous polyester resins and amorphous vinyl resins (particularly styrene-acrylic resins) are preferred, and amorphous polyester resins are more preferred. In addition, it is also a preferred embodiment to use an amorphous polyester resin and a styrene-acrylic resin in combination as the amorphous resin.It is also a preferred embodiment to use an amorphous resin having an amorphous polyester resin segment and a styrene-acrylic resin segment as the amorphous resin.

[0043] Amorphous polyester resin The amorphous polyester resin may be, for example, a condensation polymer of a polycarboxylic acid and a polyhydric alcohol. As the amorphous polyester resin, a commercially available product or a synthesized product may be used.

[0044] Examples of polycarboxylic acids include aliphatic dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, and sebacic acid), alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic acid), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, phthalic acid, and naphthalenedicarboxylic acid), anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). Among these, aromatic dicarboxylic acids are preferred as polycarboxylic acids. The polycarboxylic acid may be a trivalent or higher carboxylic acid having a crosslinked or branched structure in combination with a dicarboxylic acid. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). The polycarboxylic acids may be used alone or in combination of two or more.

[0045] Examples of polyhydric alcohols include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, etc.), and aromatic diols (e.g., ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, etc.). Among these, aromatic diols and alicyclic diols are preferred as polyhydric alcohols, and aromatic diols are more preferred. As the polyhydric alcohol, a trihydric or higher polyhydric alcohol having a crosslinked or branched structure may be used in combination with the diol. Examples of trihydric or higher polyhydric alcohols include glycerin, trimethylolpropane, and pentaerythritol. The polyhydric alcohols may be used alone or in combination of two or more.

[0046] Amorphous polyester resins can be obtained by known production methods. Specifically, for example, the polymerization temperature is set to 180°C or higher and 230°C or lower, and the reaction system is reduced in pressure as necessary, and the reaction is carried out while removing water and alcohol generated during condensation. If the raw material monomers are not soluble or compatible at the reaction temperature, a high-boiling solvent may be added as a solubilizer to dissolve them. In this case, the polycondensation reaction is carried out while distilling off the solubilizer. If a monomer with poor compatibility is present in the copolymerization reaction, it is recommended that the poorly compatible monomer be condensed in advance with the acid or alcohol to be polycondensed, and then polycondensed with the main component.

[0047] The characteristics of the resin will be explained. From the viewpoint of suppressing the generation of coarse particles and fine particles, the acid value of the resin is preferably 8 mgKOH / g or more and 20 mgKOH / g or less, and more preferably 10 mgKOH / g or more and 16 mgKOH / g or less.

[0048] The acid value is determined by the neutralization titration method specified in JIS K0070 (1992). Specifically, the acid value is determined as follows. An appropriate amount of sample was taken, 100 ml of solvent (diethyl ether / ethanol mixture) and a few drops of indicator (phenolphthalein solution) were added, and the sample was thoroughly shaken in a water bath until completely dissolved. This was titrated with 0.1 mol / L potassium hydroxide ethanol solution, and the endpoint was determined when the indicator's light red color persisted for 30 seconds. The acid value was A, the sample weight was S (g), the amount of 0.1 mol / L potassium hydroxide ethanol solution used in the titration was B (ml), and f was the factor of the 0.1 mol / L potassium hydroxide ethanol solution. A = (B × f × 5.611) / S.

[0049] The glass transition temperature (Tg) of the resin is preferably 50°C or higher and 80°C or lower, and more preferably 50°C or higher and 65°C or lower. The glass transition temperature is measured using a differential scanning calorimeter (Mac Science: DSC3110, Thermal Analysis System 001) in accordance with JIS 7121-1987. The melting point of the indium and zinc mixture is used to correct the temperature of the detector of this device, and the heat of fusion of indium is used to correct the heat quantity. The sample is placed in an aluminum pan, and the aluminum pan containing the sample is set next to an empty aluminum pan for reference, and the measurement is performed at a heating rate of 10°C / min. The glass transition temperature is determined as the temperature at the intersection of the baseline and the extension of the rising line in the endothermic portion of the DSC curve obtained by the measurement.

[0050] The weight average molecular weight (Mw) of the resin is preferably 5,000 or more and 1,000,000 or less, and more preferably 7,000 or more and 500,000 or less. The number average molecular weight (Mn) of the resin is preferably 2,000 or more and 100,000 or less. The molecular weight distribution Mw / Mn of the resin is preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less. The weight-average molecular weight and number-average molecular weight are measured by gel permeation chromatography (GPC). Molecular weight measurements by GPC are performed using a Tosoh GPC HLC-8120GPC measuring device and a Tosoh TSKgel SuperHM-M (15 cm) column in THF solvent. The weight-average molecular weight and number-average molecular weight are calculated from the measurement results using a molecular weight calibration curve prepared with monodisperse polystyrene standard samples.

[0051] The amount of resin used is not particularly limited, but may be appropriately selected depending on the solid content concentration of the resulting resin particle dispersion.

[0052] -Neutralizer- The neutralizing agent may be a basic compound capable of neutralizing polar groups such as carboxyl groups, sulfonic acid groups, and hydroxyl groups in the resin. Specifically, the neutralizing agent may be an organic base or an inorganic alkali. Examples of the organic base include triethanolamine, diethanolamine, N-methyldiethanolamine, and dimethylethanolamine. Examples of inorganic alkalis include alkali metal hydroxides (for example, sodium hydroxide, lithium hydroxide, potassium hydroxide, etc.), carbonates (for example, sodium carbonate, sodium hydrogen carbonate, etc.), and ammonia. As the neutralizing agent, in order to prevent hydrolysis of the resin, amines, which are weak bases, are preferred, and ammonia is more preferred. Furthermore, it is particularly preferred that ammonia is added in the form of an aqueous ammonia solution.

[0053] The total amount of neutralizer added is preferably 0.02 to 0.06 parts by mass, more preferably 0.02 to 0.05 parts by mass, per 10 parts by mass of resin, from the viewpoint of suppressing the generation of coarse particles and fine particles.

[0054] The neutralization rate of the resin with the neutralizing agent is preferably 60% or more and less than 150%, more preferably 60% or more and less than 145%, from the viewpoint of suppressing the generation of coarse particles and fine particles. That is, the neutralizing agent is used so that the neutralization rate of the resin falls within the above range.

[0055] The neutralization rate of a resin can be calculated using the following formula: where the acid value of the resin is AV [mg-KOH / g-resin], the valence of the neutralizing agent (basic substance) to be added is n, the molecular weight of the neutralizing agent (basic substance) to be added is Mwb, and the amount of neutralizing agent (basic substance) added per 1g of resin is mb [g]. Resin neutralization rate [%] = mb × n × 56.1 ÷ Mwb ÷ AV × 1000

[0056] -Organic solvents- Examples of the organic solvent include well-known solvents that are used in phase inversion emulsification. Among these, from the viewpoint of improving the solubility of the resin and suppressing the generation of coarse particles and fine particles, it is preferable that the organic solvent comprises one or more selected from the group consisting of esters and ketones, one or more selected from alcohols, and one or more selected from ketones and one or more selected from alcohols.

[0057] From the viewpoint of improving the solubility of the resin and suppressing the generation of coarse particles and fine particles, the amount of ketones per 10 parts by mass of the resin is preferably 4 parts by mass to 15 parts by mass, more preferably 4 parts by mass to 13 parts by mass. From the viewpoint of improving the solubility of the resin and suppressing the generation of coarse particles and fine particles, the amount of alcohols per 10 parts by mass of the resin is preferably 1 part by mass to 5 parts by mass, more preferably 1 part by mass to 4 parts by mass.

[0058] Examples of the esters include ethyl acetate, butyl acetate, propyl acetate, and isopropyl acetate. Examples of ketones include acetone, methyl ethyl ketone, cyclohexanone, butanone, and methyl isobutyl ketone. Examples of alcohols include methanol, ethanol, isopropyl alcohol, n-propanol, n-butanol, diacetone alcohol, and 2-ethylhexanol.

[0059] Among these organic resins, from the viewpoint of improving the solubility of fat and suppressing the generation of coarse particles and fine particles, it is particularly preferable that the organic resin contains methyl ethyl ketone as the ketone and isopropanol as the alcohol.

[0060] -Aqueous medium- As the aqueous medium, for example, water (distilled water, ion-exchanged water, etc.) is used. The amount of water to be added to the oil phase medium in which the resin is dissolved in the organic solvent is, for example, an amount that will cause phase inversion emulsification and reduce the amount of waste generated. Specifically, the amount of water added is preferably 50% by mass or more and 2000% by mass or less, and more preferably 100% by mass or more and 1000% by mass or less, based on the weight of the resin.

[0061] (Organic solvent removal process) In the organic solvent removal step, the organic solvent is removed from the phase inversion emulsion. The organic solvent may be removed from the phase-inverted emulsion by vacuum distillation (vacuum distillation). In the vacuum distillation method, well-known methods can be used, such as a method in which vacuum distillation is carried out using a vacuum distillation tank equipped with a stirrer while bubbling an inert gas, and a method called a wall wetter in which the phase-inverted emulsion in the vacuum distillation tank is pumped upward and vacuum distillation is carried out while forming a liquid film on the heat transfer surface of the tank above the liquid surface.

[0062] Other well-known methods for removing the organic solvent may also be employed, such as a method in which a gas (an inert gas such as nitrogen, or air) is introduced into the phase-inverted emulsion while stirring it, and the organic solvent is dried at the gas-liquid interface (exhaust air drying method), or a method in which the phase-inverted emulsion is released in a shower-like manner from pores, and dropped into, for example, a dish-shaped receiver, and this process is repeated to dry the organic solvent (shower-type solvent removal method).

[0063] By removing the organic solvent from the phase inversion emulsion, a resin particle dispersion in which resin particles are dispersed is obtained. After removing the organic solvent, the recovered organic solvent, neutralizing agent, aqueous solvent, etc. may be reused for producing a phase inversion emulsion, thereby reducing costs and environmental impact.

[0064] A surfactant may be added to the obtained resin particle dispersion. When the resin particle dispersion contains a surfactant, the dispersibility of the resin particles is improved, and the storage stability of the dispersion is improved.

[0065] Examples of surfactants include various surfactants such as anionic surfactants, amphoteric surfactants, cationic surfactants, and nonionic surfactants. Among these, anionic surfactants are preferred as surfactants from the viewpoint of improving the storage stability of the resin particle dispersion.

[0066] Examples of anionic surfactants include carboxylic acid type, sulfate ester type, sulfonic acid type, and phosphate ester type anionic surfactants. Examples of anionic surfactants include fatty acid salts, rosinate salts, naphthenate salts, ether carboxylate salts, alkenyl succinate salts, primary alkyl sulfate salts, secondary alkyl sulfate salts, alkyl polyoxyethylene sulfate salts, alkyl phenyl polyoxyethylene sulfate salts, monoacyl glycerin sulfate salts, acyl amino sulfate salts, sulfated oils, sulfated fatty acid alkyl esters, α-olefin sulfonates, secondary alkane sulfonates, α-sulfofatty acid salts, acyl isethionates, dialkyl sulfosuccinate salts, alkyl benzene sulfonates, alkyl naphthalene sulfonates, alkyl diphenyl ether disulfonates, petroleum sulfonates, lignin sulfonates, alkyl phosphate salts, alkyl polyoxyethylene phosphate salts, alkyl phenyl polyoxyethylene phosphate salts, perfluoroalkyl carboxylate salts, perfluoroalkyl sulfonates, and perfluoroalkyl phosphate esters.

[0067] Among these, from the viewpoint of improving the storage stability of the resin particle dispersion, the anionic surfactant is more preferably a sulfate ester type or sulfonic acid type anionic surfactant, and particularly preferably a sulfonic acid type anionic surfactant.

[0068] From the viewpoint of improving the storage stability of the resin particle dispersion, the content of the surfactant is preferably from 0.1 to 10% by mass, more preferably from 0.5 to 5% by mass, based on the resin.

[0069] (Characteristics of resin particle dispersion) The volume average particle size of the resin particles in the resin particle dispersion according to this embodiment is preferably 65 nm or more and 220 nm or less, and more preferably 90 nm or more and 200 nm or less. The resin particle dispersion according to this embodiment has a high yield and a narrow particle size distribution even when the volume average particle size of the resin particles is within the above range.

[0070] The volume average particle size of the resin particles is measured using a particle size distribution obtained by measurement with a laser diffraction particle size distribution analyzer (e.g., LA-700 manufactured by Horiba, Ltd.), and the cumulative distribution for the volume of the divided particle size range (channel) is calculated from the small particle size side, and the particle size that accounts for 50% of the cumulative total of all particles is measured as the volume average particle size D50v.

[0071] The content of the residual organic solvent in the resin particle dispersion according to this embodiment is preferably 3000 ppm or less, more preferably 1500 ppm or less. However, although the lower limit of the content of the residual organic solvent is 0 ppm, from the viewpoint of the cost of reducing the amount of residual organic solvent, it is, for example, 25 ppm or more. Here, ppm is a mass ratio with respect to the resin particle dispersion after the organic solvent removal step. If the content of the residual organic solvent in the resin particle dispersion is kept at 3000 ppm or less, aggregation of the resin particles is suppressed, and the storage stability of the resin particle dispersion is improved. In order to set the content of the residual organic solvent within the above range, for example, a method can be used in which the amount of the distillate recovered is calculated in advance from the amount of the phase inversion emulsion before distillation and the amount of the organic solvent component contained therein.

[0072] The solid content concentration of the resin particle dispersion according to this embodiment may be appropriately selected as needed, but is preferably from 1% by mass to 60% by mass, more preferably from 5% by mass to 50% by mass, and particularly preferably from 10% by mass to 50% by mass.

[0073] (Application) The method for producing a resin particle dispersion according to this embodiment is typically applied to a method for producing a resin particle dispersion for a toner. Other applications include inkjet inks, cosmetics, powder paints, various coating paints, and electronic paper inks.

[0074] <Toner manufacturing method / toner> The method for producing the toner according to the present embodiment includes the steps of: a step of aggregating at least the resin particles in a dispersion containing resin particles obtained by the method for producing a resin particle dispersion according to the present embodiment to form aggregated particles (hereinafter referred to as an aggregated particle forming step); a step of heating the aggregated particle dispersion in which the aggregated particles are dispersed to fuse and coalesce the aggregated particles to form toner particles (hereinafter referred to as an aggregation and coalescence step); It has.

[0075] The toner according to this embodiment is a toner having toner particles obtained by the method for producing the toner according to this embodiment.

[0076] Each step will be described in detail below. In the following description, a method for obtaining toner particles containing a colorant and a release agent will be described, but the colorant and the release agent are used as needed. Of course, additives other than the colorant and the release agent may also be used.

[0077] -Particle dispersion preparation process- In the particle dispersion liquid preparation process, a colorant particle dispersion liquid and a release agent dispersion liquid are prepared together with the resin particle dispersion liquid. prepare. ·Resin particle dispersion The resin particle dispersion liquid is produced according to the method for producing a resin particle dispersion liquid according to the present embodiment. However, a resin particle dispersion other than the resin particle dispersion obtained by the method for producing a resin particle dispersion according to this embodiment may be used in combination.

[0078] Colorant particle dispersion The colorant particle dispersion is a dispersion in which a colorant is dispersed in at least an aqueous medium. Examples of colorants include carbon black, chrome yellow, Hansa Yellow, benzidine yellow, threne yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, Balkan orange, watch young red, permanent red, brilliant carmine 3B, brilliant carmine 6B, DuPont oil red, pyrazolone red, lithol red, rhodamine B lake, lake red C, pigment red, rose bengal, aniline blue, ultramarine blue, and the like. Examples of the dye include various pigments such as phosphorus blue, chalco oil blue, methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, and malachite green oxalate, and various dyes such as acridine-based, xanthene-based, azo-based, benzoquinone-based, azine-based, anthraquinone-based, thioindigo-based, dioxazine-based, thiazine-based, azomethine-based, indigo-based, phthalocyanine-based, aniline black-based, polymethine-based, triphenylmethane-based, diphenylmethane-based, and thiazole-based dyes. The colorant may be used alone or in combination of two or more kinds.

[0079] The colorant is dispersed in an aqueous medium by a known method, and for example, a media-type disperser such as a rotary shear homogenizer, a ball mill, a sand mill, or an attritor, a high-pressure counter-impingement type disperser, etc. is preferably used. Alternatively, the colorant may be dispersed in an aqueous medium using a homogenizer with the use of a polar ionic surfactant to prepare a colorant particle dispersion.

[0080] The volume average particle size of the colorant is preferably 1 μm or less, more preferably 0.5 μm or less, and particularly preferably 0.01 μm or more and 0.5 μm or less. Examples of dispersants that are added to further stabilize the dispersion stability of the colorant in an aqueous medium and to lower the energy of the colorant in the toner include rosin, rosin derivatives, coupling agents, and polymer dispersants.

[0081] Release agent particle dispersion The release agent particle dispersion is a dispersion in which a release agent is dispersed in at least an aqueous medium. Examples of release agents include hydrocarbon waxes, natural waxes such as carnauba wax, rice wax, and candelilla wax, synthetic or mineral / petroleum waxes such as montan wax, and ester waxes such as fatty acid esters and montanic acid esters, but are not limited thereto. The release agent may be used alone or in combination of two or more kinds. The melting temperature of the release agent is preferably 50°C or higher and 110°C or lower, and more preferably 60°C or higher and 100°C or lower. The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) by using the "melting peak temperature" as described in the method for determining the melting temperature in JIS K 7121-1987 "Method for measuring transition temperatures of plastics."

[0082] The release agent is dispersed in an aqueous medium by a known method, and for example, a media-type disperser such as a rotary shear homogenizer, a ball mill, a sand mill, or an attritor, a high-pressure counter-impingement type disperser, etc. may be preferably used. Alternatively, the release agent may be dispersed in an aqueous solvent using a homogenizer with the aid of a polar ionic surfactant to prepare a release agent particle dispersion. The volume average particle size of the release agent particles is preferably 1 μm or less, and more preferably 0.01 μm or more and 1 μm or more.

[0083] -Agglomerated particle formation process- Next, the colorant particle dispersion and the release agent particle dispersion are mixed together with the resin particle dispersion. Then, in the mixed dispersion, the resin particles, colorant particles, and release agent particles are hetero-aggregated to form aggregated particles containing the resin particles, colorant particles, and release agent particles and having a diameter close to that of the target toner particles.

[0084] Specifically, for example, an aggregating agent is added to the mixed dispersion, and the pH of the mixed dispersion is adjusted to be acidic (for example, a pH of 2 or more and 5 or less), and a dispersion stabilizer is added as necessary. After that, the mixed dispersion is heated to the glass transition temperature of the resin particles (specifically, for example, a temperature of the glass transition temperature of the resin particles -30°C or more and the glass transition temperature -10°C or less), and the particles dispersed in the mixed dispersion are aggregated to form aggregated particles. In the aggregate particle formation step, for example, the above-mentioned aggregating agent may be added to the mixed dispersion at room temperature (e.g., 25°C) while stirring with a rotary shear homogenizer, the pH of the mixed dispersion may be adjusted to an acidic value (e.g., pH 2 or more and 5 or less), and a dispersion stabilizer may be added as necessary, followed by the heating.

[0085] Examples of the flocculant include a surfactant having a polarity opposite to that of the surfactant used as the dispersant added to the mixed dispersion, an inorganic metal salt, and a divalent or higher metal complex. In particular, when a metal complex is used as the flocculant, the amount of surfactant used can be reduced and the charging characteristics can be improved. If necessary, an additive that forms a complex or a similar bond with the metal ions of the flocculant may be used, and a chelating agent is preferably used as this additive.

[0086] Examples of inorganic metal salts include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate, as well as inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. The chelating agent may be a water-soluble chelating agent, such as hydroxycarboxylic acid (e.g., tartaric acid, citric acid, gluconic acid), iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), etc. The amount of the chelating agent added is, for example, preferably 0.01 parts by mass or more and 5.0 parts by mass or less, and more preferably 0.1 parts by mass or more and less than 3.0 parts by mass, per 100 parts by mass of the resin particles.

[0087] -Fusion / unification process- Next, the aggregated particle dispersion liquid in which the aggregated particles are dispersed is heated, for example, to a temperature equal to or higher than the glass transition temperature of the resin particles (for example, a temperature 10 to 30°C higher than the glass transition temperature of the resin particles), to fuse and coalesce the aggregated particles and form toner particles.

[0088] Through the above steps, toner particles are obtained. After obtaining an aggregated particle dispersion in which aggregated particles are dispersed, the toner particles may be produced through the following steps: a step of further mixing the aggregated particle dispersion with a resin particle dispersion in which resin particles are dispersed, and aggregating the aggregated particles so that further resin particles adhere to the surfaces of the aggregated particles to form second aggregated particles; and a step of heating the second aggregated particle dispersion in which the second aggregated particles are dispersed to fuse and coalesce the second aggregated particles to form toner particles having a core / shell structure.

[0089] After the fusion and coalescence process, the toner particles formed in the solution are subjected to a known washing process, a solid-liquid separation process, and a drying process to obtain dry toner particles. In the washing step, it is preferable to carry out sufficient replacement washing with ion-exchanged water from the viewpoint of electrostatic chargeability. Furthermore, the solid-liquid separation step is not particularly limited, but from the viewpoint of productivity, it is preferable to carry out suction filtration, pressure filtration, etc. Furthermore, in the drying step, there is no particular limitation on the method, but from the viewpoint of productivity, it is preferable to carry out freeze drying, flash drying, fluidized drying, vibration-type fluidized drying, etc.

[0090] The toner and its manufacturing method according to this embodiment are manufactured by, for example, adding an external additive to the obtained dry toner particles and mixing them. The mixing can be performed using, for example, a V blender, a Henschel mixer, a Loedige mixer, or the like. Furthermore, if necessary, coarse particles may be removed from the toner using a vibrating sieve, an air sieve, or the like.

[0091] Here, examples of external additives include inorganic particles such as SiO2, TiO2, Al2O3, CuO, ZnO, SnO2, CeO2, Fe2O3, MgO, BaO, CaO, KO, Na2O, ZrO2, CaO·SiO2, KO·(TiO2)n, Al2O3·2SiO2, CaCO3, MgCO3, BaSO4, and MgSO4.

[0092] The surfaces of inorganic particles as external additives are preferably subjected to a hydrophobic treatment. The hydrophobic treatment is carried out, for example, by immersing the inorganic particles in a hydrophobic treatment agent. The hydrophobic treatment agent is not particularly limited, and examples thereof include silane coupling agents, silicone oils, titanate coupling agents, and aluminum coupling agents. These may be used alone or in combination of two or more. The amount of the hydrophobic treatment agent is usually, for example, 1 part by mass or more and 10 parts by mass or less per 100 parts by mass of the inorganic particles.

[0093] Examples of external additives include resin particles (resin particles such as polystyrene, polymethyl methacrylate (PMMA), and melamine resin), cleaning agents (for example, metal salts of higher fatty acids such as zinc stearate, and particles of fluorine-based polymers).

[0094] The amount of the external additive added is, for example, preferably 0.01% by mass or more and 5% by mass or less, and more preferably 0.01% by mass or more and 2.0% by mass or less, based on the toner particles.

[0095] -Characteristics of toner- In the toner according to the present embodiment, the toner particles may be toner particles having a single layer structure, or may be toner particles having a so-called core-shell structure composed of a core (core particle) and a coating layer (shell layer) that coats the core. Here, the toner particles having a core-shell structure may be composed of, for example, a core containing a binder resin and, if necessary, other additives such as a colorant and a release agent, and a coating layer containing the binder resin.

[0096] The volume average particle size (D50v) of the toner particles is preferably 2 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less.

[0097] The various average particle sizes and particle size distribution indices of the toner particles are measured using a Coulter Multisizer II (manufactured by Beckman Coulter), and the electrolyte is measured using an ISOTON-II (manufactured by Beckman Coulter). For the measurement, 0.5 mg to 50 mg of the sample to be measured is added to 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzene sulfonate) as a dispersant, and this is then added to 100 ml to 150 ml of the electrolyte. The electrolyte solution containing the suspended sample is dispersed for 1 minute using an ultrasonic disperser, and the particle size distribution of particles with a particle size range of 2 μm to 60 μm is measured using a Coulter Multisizer II with an aperture diameter of 100 μm. The number of particles sampled is 50,000. Based on the particle size distribution measured, cumulative distributions of volume and number are drawn for each divided particle size range (channel) from the smallest diameter side, and the particle size at 16% of the cumulative total is defined as the volume particle size D16v, the number particle size D16p, the particle size at 50% of the cumulative total as the volume average particle size D50v, the cumulative number average particle size D50p, and the particle size at 84% of the cumulative total as the volume particle size D84v and the number particle size D84p. Using these, the volumetric particle size distribution index (GSDv) is (D84v / D16v) 1 / 2 , the number particle size distribution index (GSDp) is (D84p / D16p) 1 / 2 It is calculated as:

[0098] The average circularity of the toner particles is preferably 0.94 or more and 1.00 or less, and more preferably 0.95 or more and 0.98 or less.

[0099] The average circularity of toner particles is calculated by (circular equivalent perimeter) / (perimeter) [(perimeter of a circle having the same projected area as the particle image) / (perimeter of the particle projected image)]. Specifically, this value is measured by the following method. First, the toner particles to be measured are sucked and collected, forming a flat flow, and a still image of the particles is captured by instantaneously activating a strobe light, and the particle image is analyzed using a flow-type particle image analyzer (FPIA-3000 manufactured by Sysmex Corporation).The number of samples to be sampled when calculating the average circularity is 3,500. When the toner contains external additives, the toner (developer) to be measured is dispersed in water containing a surfactant, and then ultrasonic treatment is performed to obtain toner particles from which the external additives have been removed.

[0100] <Electrostatic image developer> The electrostatic image developer according to this embodiment contains at least the toner according to this embodiment. The electrostatic image developer according to this embodiment may be a one-component developer containing only the toner according to this embodiment, or may be a two-component developer containing the toner mixed with a carrier.

[0101] The carrier is not particularly limited, and examples thereof include known carriers, such as coated carriers in which the surface of a core material made of magnetic powder is coated with a coating resin, magnetic powder dispersion carriers in which magnetic powder is dispersed and blended in a matrix resin, and resin-impregnated carriers in which porous magnetic powder is impregnated with a resin. The magnetic powder dispersion type carrier and the resin impregnated type carrier may be a carrier in which the constituent particles of the carrier are used as a core material and are coated with a coating resin. [Example]

[0102] Examples of the present invention will be described below, but the present invention is not limited to the following examples. In the following description, unless otherwise specified, all "parts" and "%" are based on mass.

[0103] <Synthesis of amorphous polyester resin (1)> Terephthalic acid: 69 parts Trimellitic acid: 31 parts Ethylene glycol: 48 parts 1,5-pentanediol: 47 parts The above materials were placed in a reaction vessel equipped with a stirrer, condenser, nitrogen gas inlet tube, thermometer, and temperature control equipment. The temperature was raised to 220°C over 1 hour under a nitrogen gas flow, and 1 part of titanium tetraethoxide was added for every 100 parts of the above materials. The temperature was raised to 240°C over 0.5 hours while distilling off the resulting water. The dehydration condensation reaction was continued at 240°C for 1 hour, and then the reaction mixture was cooled. This resulted in amorphous polyester resin (1) with an acid value of 8.0 mgKOH / g, a weight-average molecular weight of 139,000, and a glass transition temperature of 60°C.

[0104] <Synthesis of amorphous polyester resin (2)> Amorphous polyester resin (2) having an acid value of 12.5 mgKOH / g, a weight average molecular weight of 127,000, and a glass transition temperature of 59°C was obtained in the same manner as for amorphous polyester resin (A), except that the amount of ethylene glycol was changed to 43.5 parts and the amount of 1,5-pentanediol was changed to 45.5 parts.

[0105] <Synthesis of amorphous polyester resin (3)> Amorphous polyester resin (3) having an acid value of 20.0 mgKOH / g, a weight average molecular weight of 116,000, and a glass transition temperature of 58°C was obtained in the same manner as for amorphous polyester resin (A), except that the amount of ethylene glycol was changed to 36 parts and the amount of 1,5-pentanediol was changed to 39 parts.

[0106] <Synthesis of amorphous polyester resin (4)> Amorphous polyester resin (4) having an acid value of 7.0 mgKOH / g, a weight average molecular weight of 140,000, and a glass transition temperature of 60°C was obtained in the same manner as for amorphous polyester resin (A), except that the amount of ethylene glycol was changed to 49 parts and the amount of 1,5-pentanediol was changed to 47.5 parts.

[0107] <Synthesis of amorphous polyester resin (5)> Amorphous polyester resin (5) having an acid value of 21.0 mgKOH / g, a weight average molecular weight of 113,000, and a glass transition temperature of 58°C was obtained in the same manner as for amorphous polyester resin (A), except that the amount of ethylene glycol was changed to 35 parts and the amount of 1,5-pentanediol was changed to 38 parts.

[0108] <Synthesis of crystalline polyester resin> Decanedioic acid: 81 parts Hexanediol: 47 parts The above materials were charged into a reaction vessel, and the temperature was raised to 160°C over 1 hour. After confirming that the reaction system was uniformly stirred, 0.03 parts of dibutyltin oxide was added. The temperature was raised to 200°C over 6 hours while distilling off the produced water, and stirring was continued at 200°C for 4 hours. The reaction liquid was then cooled, solid-liquid separation was performed, and the solid was dried at 40°C under reduced pressure to obtain a crystalline polyester resin (melting point 64°C, weight average molecular weight 15,000).

[0109] <Preparation of Crystalline Polyester Resin Dispersion> Crystalline polyester resin: 50 parts Anionic surfactant (Dai-ichi Kogyo Seiyaku Co., Ltd., Neogen RK): 2 parts Ion-exchanged water: 200 parts The above materials were heated to 120°C and dispersed using a pressure discharge Gaulin homogenizer. When the volume average particle size reached 180 nm, the particles were collected to obtain a crystalline polyester resin dispersion with a solid content of 20%.

[0110] <Preparation of release agent particle dispersion> Paraffin wax (HNP-9 manufactured by Nippon Seiro Co., Ltd.): 100 parts Anionic surfactant (Dai-ichi Kogyo Seiyaku Co., Ltd., Neogen RK): 1 part Ion-exchanged water: 350 parts The above materials were mixed and heated to 100°C, and dispersed using a pressure discharge Gaulin homogenizer to obtain a release agent particle dispersion in which release agent particles with a volume average particle size of 200 nm were dispersed. Ion-exchanged water was added to this release agent particle dispersion to adjust the solid content to 20%, and this was used as a release agent particle dispersion.

[0111] <Preparation of Colorant Particle Dispersion> Carbon black (Cabot, Regal 330): 50 parts Anionic surfactant (Dai-ichi Kogyo Seiyaku Co., Ltd., Neogen RK): 5 parts Ion-exchanged water: 195 parts The above materials were mixed and dispersed for 10 minutes at 240 MPa using a Starburst (manufactured by Sugino Machine Co., Ltd.) to obtain a colorant particle dispersion liquid with a solid content of 20%.

[0112] <Preparation of silica particles> After thoroughly mixing water, methanol, and aqueous ammonia, tetramethoxysilane and aqueous ammonia were added dropwise while heating. Next, hexamethyldisilazane (HMDS) was added to the silica sol suspension obtained by the reaction to perform a hydrophobic treatment, and the silica sol was dried to obtain silica particles. The silica particles were then crushed to obtain silica particles with a volume average particle size (D) of 50v 160nm.

[0113] Example 1 [Synthesis of resin particle dispersion (1)] An emulsification tank equipped with a stirrer with anchor impellers (Di / Dt=0.98), a condenser, a thermometer, and a temperature control device was charged with 10 parts of amorphous polyester resin (2) as a resin, 9 parts of methyl ethyl ketone (MEK) as an organic solvent, and 2.5 parts of isopropanol (IPA) as an organic solvent, and then stirred at 60°C for 30 minutes to dissolve the resin. To the resulting resin solution, ammonia water was added as a neutralizing agent in an amount equivalent to 0.04 parts ammonia per 10 parts resin (neutralization rate of resin = 124%). The temperature inside the emulsification tank (i.e., the liquid temperature of the resin solution) was adjusted to 50°C and the stirring speed to 40 rpm. Then, pure water adjusted to the same temperature as inside the tank was continuously added at a rate of 0.2 parts / min to cause phase inversion emulsification. This resulted in a phase inversion emulsion. The maximum stirring power value during phase inversion emulsification was 9.1 W per unit resin mass (kg). Thereafter, the organic solvent was removed from the phase inversion emulsion until the concentration of the residual organic solvent in the phase inversion emulsion became 1000 ppm, thereby obtaining a resin particle dispersion (1).

[0114] <Examples 2 to 30, Comparative Examples 1 and 2> A resin particle dispersion was obtained in the same manner as in Example 1, except that the conditions for preparing the phase inversion emulsion were changed as shown in Table 1.

[0115] <Evaluation> [Occurrence of coarse particles] The occurrence of coarse particles in the resin particle dispersion of each example was evaluated as follows. Observation was performed at 30,000x magnification using a scanning electron microscope (SEM: S-4700, manufactured by Hitachi, Ltd.) in 20 fields of view, and the number of particles with a particle size twice or more of the volume average particle size was calculated as the number of coarse particles, and evaluated according to the following evaluation criteria. A: The number of coarse particles is less than 1 B: 1 large particle C: 2 large particles D: 3 large particles E: Number of coarse particles is 4 or more

[0116] [Fine particle generation status] The occurrence of fine particles in the resin particle dispersion of each example was evaluated as follows. Observation was performed at 80,000x magnification using a scanning electron microscope (SEM: S-4700, manufactured by Hitachi, Ltd.) in 20 fields of view, and the number of particles having a volume average diameter of 1 / 3 or less was determined as the number of microparticles, and evaluated according to the following criteria. A: The number of microparticles is less than 1 B: Number of microparticles is 1 to 3 C: Number of microparticles is 4 to 9 D: Number of microparticles is 10 or more and 14 or less E: 15 or more microparticles

[0117] [Toner production] The resin particle dispersion of each example was used as the amorphous resin particle dispersion, and a toner was prepared as follows.

[0118] Ion-exchanged water: 200 parts Amorphous polyester resin dispersion: 150 parts Crystalline polyester resin dispersion: 10 parts Release agent particle dispersion: 10 parts Colorant particle dispersion: 15 parts Anionic surfactant (TaycaPower): 2.8 parts The above materials were placed in a jacketed temperature-controlled stirring tank, and 0.1 N nitric acid was added to adjust the pH to 3.5. An aqueous polyaluminum chloride solution prepared by dissolving 2 parts of polyaluminum chloride (Oji Paper Co., Ltd., 30% powder product) in 30 parts of ion-exchange water was then added. After dispersion using a homogenizer, the mixture was heated to 45°C and maintained at that temperature until the volume average particle size reached 4.9 μm. Next, 60 parts of amorphous polyester resin dispersion was added and maintained for 30 minutes. When the volume average particle size reached 5.2 μm, another 60 parts of amorphous polyester resin dispersion (1) was added and maintained for 30 minutes. Next, 20 parts of a 10% NTA (nitrilotriacetic acid) metal salt aqueous solution (Chilest 70, Chelest Co., Ltd.) was added, and the pH was adjusted to 9.0 by adding 1 N sodium hydroxide aqueous solution. Next, 1 part of an anionic surfactant (TaycaPower) was added, and the mixture was heated to 85°C with continued stirring and maintained for 5 hours. It was then cooled to 20°C at a rate of 20°C / min. Then, the mixture was filtered, thoroughly washed with ion-exchanged water, and dried to obtain toner particles. Next, 2.3 parts of silica particles were mixed with 100 parts of toner particles using a Henschel mixer at a peripheral speed of 20 m / s for 15 minutes to obtain a toner.

[0119] [Evaluation of image density unevenness] In a high temperature and humidity environment (28°C, 85% RH), 100 images with an image density of 30% were printed using a DocuCentre-IV C5570 manufactured by Fuji Xerox Co., Ltd. Ten random points on the printed images were measured using an X-Rite 938 image densitometer (manufactured by X-Rite), and the image density difference, which is the difference between the maximum and minimum measured densities, was determined. The image density unevenness was evaluated according to the following criteria. A: Image density difference is 0.1 or less B: Image density difference is greater than 0.1 and less than or equal to 0.15 C: Image density difference is greater than 0.15 and less than 0.2 D: Image density difference is greater than 0.2 and less than 0.3 E: Image density difference is more than 0.3

[0120] [Table 1-1]

[0121] [Table 1-2]

[0122] From the above results, it can be seen that the generation of coarse particles and fine particles in the resin particle dispersion liquid is suppressed in this example compared to the comparative example. It is also apparent that the toner produced using the resin particle dispersion of this example suppresses the occurrence of image density unevenness compared to the comparative example.

Claims

1. a step of adding a neutralizing agent to a resin solution obtained by dissolving a resin having an acid value in an organic solvent to neutralize the resin, and then adding an aqueous medium to phase-invert emulsify the resin to obtain a phase-inverted emulsion; removing the organic solvent from the phase inversion emulsion; and In the step of obtaining the phase inversion emulsion, when the resin solution to which the aqueous medium has been added is stirred to effect phase inversion emulsification, the maximum stirring power value per unit resin mass (kg) is 0.4 W or more and 20 W or less; The phase inversion emulsification of the resin is carried out in an emulsification tank equipped with an anchor agitator, The ratio Di / Dt of the blade diameter Di of the anchor stirring blade to the tank diameter Dt of the emulsification tank is 0.90 or more and 0.99 or less, The method for producing a resin particle dispersion liquid, wherein the rotation speed of the anchor stirring blade is 10 rpm or more and 100 rpm or less.

2. 2. The method for producing a resin particle dispersion according to claim 1, wherein the acid value of the resin is 8 mgKOH / g or more and 20 mgKOH / g or less.

3. 3. The method for producing a resin particle dispersion according to claim 1, wherein the resin is a polyester resin.

4. the organic solvent contains one or more selected from ketones and one or more selected from alcohols, 4. The method for producing a resin particle dispersion liquid according to claim 1, wherein an amount of the ketones relative to 10 parts by mass of the resin is 4 parts by mass or more and 15 parts by mass or less, and an amount of the alcohols relative to 10 parts by mass of the resin is 1 part by mass or more and 5 parts by mass or less.

5. 5. The method for producing a resin particle dispersion liquid according to claim 4, wherein the ketone is methyl ethyl ketone and the alcohol is isopropanol.

6. the neutralizing agent is ammonia, 6. The method for producing a resin particle dispersion according to claim 1, wherein the total amount of the neutralizing agent added is 0.02 parts by mass or more and 0.06 parts by mass or less with respect to 10 parts by mass of the resin.

7. 7. The method for producing a resin particle dispersion according to claim 1, wherein the temperature of the resin solution after adding the aqueous medium when undergoing phase inversion emulsification is 20° C. or higher and 80° C. or lower.

8. The aqueous medium is continuously added to the resin solution, 8. The method for producing a resin particle dispersion according to claim 1, wherein the rate of addition of the aqueous medium to 10 parts by mass of the resin is 0.03 parts by mass / minute or more and 0.80 parts by mass / minute or less.

9. The method for producing a resin particle dispersion according to any one of claims 1 to 8, wherein a resin particle dispersion for a toner is produced.

10. a step of obtaining a resin particle dispersion by the method for producing a resin particle dispersion according to any one of claims 1 to 9; a step of aggregating at least the resin particles in the resin particle dispersion to form aggregated particles; a step of heating the aggregated particle dispersion in which the aggregated particles are dispersed to fuse and coalesce the aggregated particles to form toner particles; A method for producing a toner for developing electrostatic images, comprising:

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