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 has a high yield rate and contains resin particles having a narrow particle size distribution.SOLUTION: There is provided a method for producing a resin particle dispersion which comprises a step of preparing a phase inversion emulsified liquid obtained by subjecting a resin to phase inversion emulsification using an organic solvent and an aqueous medium and a step of removing the organic solvent from the phase inversion emulsified liquid stored in a distillation tank by vacuum distillation, wherein in a pressure reduction speed when the organic solvent concentration of the phase inversion emulsified liquid is in the range of 30 mass% or less and 1 mass% or more during the vacuum distillation, the vapor pressure of the environment in the distillation tank is higher than the vapor pressure (vapor pressure + 5kPa) and reaches a set depressurization pressure of the vacuum distillation is 0.01 kPa / min or more and 0.5 pKa / min or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a resin particle dispersion, 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 solvent recovery device having "a heating tank having a stirring means and a heating means, an evaporated gas passage, an evaporated gas condensation section, a condensate recovery section, and a pressure reduction means, wherein the evaporated gas passage is composed of two or more pipes having different angles, the pipes in the evaporated gas passage are installed with a gradient in the direction in which the liquid flows into the heating tank, and the pipe directly connected to the heating tank has a dead end provided at the end of the pipe on the opposite side to the side connected to the heating tank with respect to the direction in which the evaporated gas travels, and a connection part with another pipe provided on the heating tank side of the dead end of the pipe." [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-144395 Summary of the Invention [Problem to be solved by the invention]

[0004] The object of the present invention is to provide a method for producing a resin particle dispersion liquid, which includes the steps of preparing a phase-inverted emulsion by phase-inverting a resin using an organic solvent and an aqueous medium, and removing the organic solvent from the phase-inverted emulsion contained in a distillation tank by vacuum distillation, and which has a higher yield and a narrow particle size distribution than when the vacuum rate during vacuum distillation is such that the organic solvent concentration of the phase-inverted emulsion is in the range of 1% by mass or less and 30% by mass or more, and the environment inside the distillation tank is equal to or greater than the vapor pressure (vapor pressure + 5 kPa) and the vacuum rate until the set vacuum pressure of the vacuum distillation is reached is less than 0.01 kPa / min or more than 0.5 kPa / min. [Means for solving the problem]

[0005] Specific means for solving the above problems include the following aspects. <1> a step of preparing a phase inversion emulsion by phase inversion emulsifying a resin using an organic solvent and an aqueous medium; removing the organic solvent from the phase inversion emulsion contained in the distillation tank by vacuum distillation; and A method for producing a resin particle dispersion, wherein the pressure reduction rate during the vacuum distillation is such that the organic solvent concentration in the phase inversion emulsion is in the range of 30% by mass or less and 1% by mass or more, the environment inside the distillation tank is equal to or greater than the vapor pressure (vapor pressure + 5 kPa) and the pressure reduction rate until the set vacuum pressure of the vacuum distillation is reached is 0.01 kPa / min or more and 0.5 kPa / min or less. <2> The temperature of the phase inversion emulsion during the reduced pressure distillation is 30°C or higher and 70°C or lower. <1> 1. A method for producing a resin particle dispersion liquid according to claim 1. <3> During the vacuum distillation, the heating temperature for heating the tank wall of the distillation tank is 50°C or higher and 95°C or lower. <1> or <2> 1. A method for producing a resin particle dispersion liquid according to claim 1. <4> Manufacture of resin particle dispersion for toner <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> <1> ~ <4> 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: <6> <5> 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]

[0006] <1> , or <4> According to the invention, a method for producing a resin particle dispersion liquid includes a step of preparing a phase-inverted emulsion by phase-inverting emulsification of a resin using an organic solvent and an aqueous medium, and a step of removing the organic solvent from the phase-inverted emulsion contained in a distillation tank by vacuum distillation. The method provides a method for producing a resin particle dispersion liquid having resin particles with a narrow particle size distribution and a higher yield when the vacuum distillation is carried out at a vacuum rate when the organic solvent concentration of the phase-inverted emulsion is in the range of 30% by mass or less and 1% by mass or more, and the environment in the distillation tank is at or above the vapor pressure (vapor pressure + 5 kPa) and the vacuum rate until the set vacuum pressure of the vacuum distillation is reached is less than 0.01 kPa / min or more than 0.5 kPa / min.

[0007] <2> According to the invention, there is provided a method for producing a resin particle dispersion liquid having resin particles with a narrower particle size distribution than when the temperature of the phase inversion emulsion during pressure distillation is higher than 70°C.

[0008] <3> According to the present invention, a method for producing a resin particle dispersion liquid is provided that allows a higher yield compared to when the temperature at which the vessel wall of the distillation vessel is heated during reduced pressure distillation is less than 50°C.

[0009] <5> , or <6> According to the invention, a method for producing a resin particle dispersion, which includes the steps of preparing a phase-inverted emulsion by phase-inverting emulsification of a resin using an organic solvent and an aqueous medium, and removing the organic solvent from the phase-inverted emulsion contained in a distillation tank by vacuum distillation, provides a method for producing a toner for developing electrostatic images having resin particles with a narrow particle size distribution and a toner for developing electrostatic images, which has a higher yield than when a method for producing a resin particle dispersion is applied in which the vacuum distillation is carried out at a vacuum rate when the organic solvent concentration of the phase-inverted emulsion is in the range of 1% by mass or more and 30% by mass or less, the environment in the distillation tank is at or above the vapor pressure (vapor pressure + 5 kPa) and the vacuum rate until the set vacuum pressure of the vacuum distillation is reached is less than 0.01 kPa / min or more than 0.5 kPa / min. DETAILED DESCRIPTION OF THE INVENTION

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] In this specification, "toner for developing electrostatic images" is also simply referred to as "toner."

[0016] <Method of manufacturing resin particle dispersion> The method for producing a resin particle dispersion according to this embodiment includes the steps of preparing a phase-inversion emulsion by phase-inversion emulsifying a resin using an organic solvent and an aqueous medium, and removing the organic solvent from the phase-inversion emulsion contained in a distillation tank by vacuum distillation. In the method for producing a resin particle dispersion according to this embodiment, the decompression rate during vacuum distillation when the organic solvent concentration of the phase inversion emulsion is in the range of 30% by mass or less and 1% by mass or more, the environment inside the distillation tank is equal to or greater than the vapor pressure (vapor pressure + 5 kPa) and the decompression rate until the set vacuum pressure of the vacuum distillation is reached is 0.01 kPa / min or more and 0.5 kPa / min or less.

[0017] The method for producing a resin particle dispersion according to this embodiment provides a resin particle dispersion having resin particles with a narrow particle size distribution at a high yield. The reason for this is presumed to be as follows.

[0018] For example, the resin particle dispersion is prepared by dissolving a resin in an organic solvent, mixing it with water, and then finely dispersing it in an aqueous medium by phase inversion emulsification, and then removing the organic solvent by vacuum distillation.

[0019] However, in the vacuum distillation of a phase-inverted emulsion containing an organic solvent, resin particles are arranged around the bubbles that are generated during evaporation of the organic solvent, and the interfacial tension of the bubbles increases, causing excessive foaming in the distillation tank, which can lead to entrainment of the resin into the distillate, resulting in a decrease in yield. On the other hand, this phenomenon can be suppressed by reducing the pressure reduction rate and suppressing the distillation rate, but if the distillation rate is made too slow, the resin particles in the phase inversion emulsion will be exposed to the unstable region between the oil and water phases for a long time, which may cause a deterioration in the particle size distribution of the resin particles.

[0020] Therefore, in the method for producing a resin particle dispersion according to this embodiment, the decompression rate during vacuum distillation when the organic solvent concentration of the phase inversion emulsion is in the range of 30% by mass or less and 1% by mass or more, and when the environment inside the distillation tank is equal to or greater than the vapor pressure (vapor pressure + 5 kPa) and the set vacuum pressure for vacuum distillation is reached, is set to 0.01 kPa / min or more and 0.5 kPa / min or less.

[0021] When the organic solvent concentration in the phase inversion emulsion is in the range of 30% by mass or less and 1% by mass or more, excessive foaming occurs. Therefore, the pressure reduction rate is reduced to 0.5 kPa / min or less when the organic solvent concentration of the phase inversion emulsion is within the range, preventing excessive foaming and preventing resin from being mixed into the distillate due to droplet entrainment, thereby preventing a decrease in yield. On the other hand, by setting the pressure reduction rate at 0.01 kPa / min or more when the organic solvent concentration of the phase inversion emulsion is in the range, the resin particles in the phase inversion emulsion are prevented from being exposed to the unstable region of the oil and water phases for a long period of time, and deterioration of the particle size distribution of the resin particles is suppressed.

[0022] However, if the environment in the distillation tank exceeds the vapor pressure, excessive foaming will not occur, so the pressure reduction rate may exceed 0.5 kPa / min until the environment in the distillation tank reaches the vapor pressure. After the set vacuum pressure of the vacuum distillation is reached, the distillation is carried out while maintaining the pressure in the distillation tank, so the pressure reduction rate is set to less than 0.01 kPa / min to suppress pressure fluctuations.

[0023] From the above, it is presumed that the method for producing a resin particle dispersion according to this embodiment can provide a resin particle dispersion having resin particles with a narrow particle size distribution at a high yield.

[0024] The resin particle dispersion obtained by the method for producing a resin particle dispersion according to this embodiment has a narrow particle size distribution of the resin particles, and therefore, when used as a toner (particularly when used as a toner production method using an emulsion aggregation method), a toner with a narrow particle size distribution can be obtained.

[0025] The method for producing a resin particle dispersion according to this embodiment will be described in detail below.

[0026] (Phase inversion emulsion preparation process) In the phase inversion emulsion preparation step, a phase inversion emulsion is prepared by subjecting a resin to phase inversion emulsification using an organic solvent and an aqueous medium. The phase inversion emulsion is obtained by a phase inversion emulsification method. 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.

[0027] The phase inversion emulsion can be produced, for example, by the following method. 1) A method in which a resin is dissolved in an organic solvent, a neutralizing agent is added to the resulting resin solution to neutralize the resin, and then an aqueous medium is added to the resin solution to cause phase inversion emulsification. 2) A method in which a resin is dissolved in a solvent containing an organic solvent, a portion of a neutralizing agent, and an aqueous medium, and the resin is neutralized, and then the aqueous medium is added to the resin solution to cause phase inversion emulsification. 3) A method in which a resin is dissolved in an organic solvent, a neutralizing agent is added to the resulting resin solution to neutralize the resin, and then an aqueous medium is added to the resin solution, and the temperature of the mixture is changed while stirring and mixing to cause phase inversion emulsification.

[0028] 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.

[0029] -resin- 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.

[0030] The resin is preferably a resin having a polar group such as a carboxyl group, a sulfonic acid group, or a hydroxyl group, and is particularly preferably a resin having an acid value.

[0031] 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.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] The characteristics of the resin will be explained. 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] -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.

[0043] The neutralization rate of the resin with the neutralizer is 60% or more and less than 150%, but from the viewpoint of improving yield and narrowing particle size distribution, it is more preferably 60% or more and less than 145%, and even more preferably 65% ​​or more and 130% or less. That is, the neutralizing agent is used so that the neutralization rate of the resin falls within the above range.

[0044] 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 (i.e., basic substance) to be added is n, the molecular weight of the neutralizing agent (i.e., basic substance) to be added is Mwb, and the amount of neutralizing agent (i.e., basic substance) added per 1 g of resin is mb [g]. Resin neutralization rate [%] = mb × n × 56.1 ÷ Mwb ÷ AV × 1000

[0045] -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, the organic solvent preferably contains one or more organic solvents selected from the group consisting of esters and ketones, and one or more organic solvents selected from alcohols, and more preferably contains one or more organic solvents selected from the group consisting of ketones, and one or more organic solvents selected from alcohols.

[0046] 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.

[0047] -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.

[0048] (Organic solvent removal process) In the organic solvent removal step, the organic solvent is removed from the phase-inverted emulsion contained in the distillation tank by distillation under reduced pressure.

[0049] The vacuum distillation can be carried out by a well-known method, such as a method in which a vacuum distillation tank equipped with a stirrer is used to carry out vacuum distillation while bubbling an inert gas, or 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.

[0050] During vacuum distillation, when the organic solvent concentration of the phase inverted emulsion is in the range of 1% by mass or more and 30% by mass or less, the pressure reduction rate until the set vacuum pressure of the vacuum distillation is reached in an environment in the distillation tank that is equal to or higher than the vapor pressure (vapor pressure + 5 kPa) is 0.01 kPa / min or more and 0.5 kPa / min or less. From the viewpoint of improving the yield and narrowing the particle size distribution, the pressure is more preferably 0.05 kPa / min or more and 0.4 kPa / min or less.

[0051] The pressure reduction rate is controlled, for example, by the pressure inside the distillation tank. The pressure in the distillation tank is controlled by a vacuum pump connected to the distillation tank via a condenser for condensing the evaporated organic solvent, and at least a regulating valve connected between the condenser and the vacuum pump. During the reduced pressure distillation, the vacuum pump may be operated either intermittently or continuously. The pressure in the distillation tank may be controlled by simultaneously introducing air or an inert gas into the distillation tank. In order to suppress the amount of incompletely condensed gas flowing into the equipment for treating the trace gas, it is preferable to provide a first regulating valve connected to the distillation tank side and a second regulating valve connecting the vacuum pump outlet and vacuum pump inlet, thereby controlling the pressure inside the distillation tank.

[0052] The temperature of the phase-inverted emulsion during vacuum distillation is preferably 30°C or higher and 70°C or lower, more preferably 35°C or higher and 65°C or lower. By maintaining the temperature of the phase-inverted emulsion at 30°C or higher during vacuum distillation, the decrease in the evaporation rate of the organic solvent during vacuum distillation is suppressed. By keeping the temperature of the phase inversion emulsion below 70°C during vacuum distillation, fusion of resin particles and Hydrolysis of the resin is suppressed, and the particle size distribution of the resin particles can be easily narrowed.

[0053] The temperature at which the wall of the distillation tank is heated during reduced pressure distillation is preferably 50°C or higher and 95°C or lower, more preferably 55°C or higher and 90°C or lower. The yield is improved by heating the wall of the distillation tank to a temperature of 50°C or higher and 95°C or lower during vacuum distillation.

[0054] Here, the heating temperature for heating the tank wall of the distillation tank corresponds to the temperature of the heating fluid in the jacket through which the heating fluid flows to heat the tank wall of the distillation tank. More specifically, the heating temperature is the temperature of the heating fluid at the inlet through which the heating fluid is introduced into the jacket (also referred to as the "jacket inlet temperature").

[0055] By the above-described vacuum distillation, the organic solvent is removed from the phase-inverted emulsion, and a resin particle dispersion 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] (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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] (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.

[0066] <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.

[0067] The toner according to this embodiment is a toner having toner particles obtained by the method for producing the toner according to this embodiment.

[0068] 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.

[0069] -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.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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."

[0074] 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.

[0075] -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.

[0076] 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.

[0077] 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.

[0078] 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.

[0079] -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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] 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.

[0085] 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).

[0086] 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.

[0087] -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.

[0088] 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.

[0089] 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:

[0090] 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.

[0091] 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.

[0092] <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.

[0093] 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]

[0094] 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.

[0095] <<Example 1>> <Synthesis of amorphous polyester resin> Terephthalic acid: 69 parts Trimellitic acid: 31 parts Ethylene glycol: 43.5 parts 1,5-pentanediol: 45.5 parts The above materials were placed in a reactor 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 yielded an amorphous polyester resin with an acid value of 12.5 mgKOH / g, a weight-average molecular weight of 127,000, and a glass transition temperature of 59°C.

[0096] <Preparation of phase inversion emulsion> 10 parts of amorphous polyester resin, 12 parts of methyl ethyl ketone (MEK), and 4 parts of isopropanol (IPA) were added to a stirring tank equipped with a stirrer, a condenser, a thermometer, and a temperature control device, and the resin was dissolved by stirring at 50°C for 30 minutes. To the obtained resin solution, ammonia water was added as a neutralizing agent in an amount equivalent to 0.5% by mass of ammonia, and 20 parts of water was added while stirring to phase-invert emulsify the resin, yielding a phase-inverted emulsion with an organic solvent concentration of 35%.

[0097] <Preparation of Resin Particle Dispersion> The phase inversion emulsion was transferred to a distillation tank equipped with a stirrer fitted with wall-wetter blades, a condenser, a thermometer, a temperature controller, a pressure gauge, a pressure control valve, and a vacuum pump. While stirring with the wall-wetter blades to form a wetted wall, the jacket inlet temperature was set to 70°C, and the temperature of the phase inversion emulsion in the tank was adjusted to 50°C. The pressure in the tank was then reduced to the vapor pressure, and distillation was initiated. The pressure reduction rate was controlled at 0.2 kPa / min in all ranges where the organic solvent concentration in the tank was between 35% and over 30%, between 30% and over 1%, and less than 1% by mass, until the set reduced pressure was reached. Distillation was continued until the residual organic solvent concentration in the phase inversion emulsion reached 3,000 ppm, yielding a resin particle dispersion (1).

[0098] <<Examples 2 to 12, Comparative Examples 1 and 2>> A resin particle dispersion was prepared in the same manner as in Example 1, except that the vacuum distillation conditions were changed according to Table 1.

[0099] <<Evaluation>> <Evaluation of particle size distribution of resin particles in resin particle dispersion> The phase inversion emulsion before vacuum distillation and the resin particle dispersion after vacuum distillation were each diluted, and the volume particle size distribution (GSDv) of the resin particles was compared using a NANOTRAC_WAVE (Microtrac Bell) to determine the level of deterioration. GSDv was calculated from the volume frequency as ((D84 / D50) + (D50 / D16)) / 2 and evaluated according to the following criteria, with G3△ or higher being considered acceptable. G1◎: The difference in GSDv of resin particles before and after vacuum distillation is less than 0.005 G2○: The difference in GSDv of resin particles before and after vacuum distillation is 0.005 or more and less than 0.01 G3△: The difference in GSDv of resin particles before and after vacuum distillation is 0.01 or more and less than 0.02 G4×: The difference in GSDv of resin particles before and after vacuum distillation is 0.02 or more

[0100] <Acquisition rate evaluation> The turbidity of resin particles diluted to a known solid content was measured in advance, and a calibration curve of turbidity versus solid content was created. The turbidity of the organic solvent recovered from the distillate was measured, and the ratio of the amount of resin mixed into the distillate to the amount of resin in the raw material was determined from the solid content. The yield was judged according to the following criteria, with a score of fair or better considered acceptable. G1◎: The amount of resin mixed in the distillate is less than 0.1% by mass G2○: The amount of resin mixed in the distillate is 0.1% by mass or more but less than 0.5% by mass G3△: The amount of resin mixed in the distillate is 0.5% by mass or more but less than 1.0% G4×: The amount of resin mixed in the distillate is 1.0% by mass or more

[0101] [Table 1]

[0102] From the above results, it can be seen that in this example, a resin particle dispersion liquid having resin particles with a narrow particle size distribution can be obtained with a higher yield than in the comparative example.

Claims

1. a step of preparing a phase inversion emulsion by phase inversion emulsifying a resin using an organic solvent and an aqueous medium; removing the organic solvent from the phase inversion emulsion contained in the distillation tank by vacuum distillation; and a pressure reduction rate during the vacuum distillation when the organic solvent concentration of the phase inversion emulsion is in the range of 1% by mass or more to 30% by mass or more, the environment inside the distillation tank is an environment of the vapor pressure or more (vapor pressure + 5 kPa) or less, and the pressure reduction rate until the set vacuum pressure of the vacuum distillation is reached is 0.01 kPa / min or more and 0.5 kPa / min or less.

2. 2. The method for producing a resin particle dispersion according to claim 1, wherein the temperature of the phase inversion emulsion during the reduced pressure distillation is 30°C or higher and 70°C or lower.

3. 3. The method for producing a resin particle dispersion according to claim 1, wherein the temperature at which the wall of the distillation tank is heated during the reduced pressure distillation is 50°C or higher and 95°C or lower.

4. a step of producing a resin particle dispersion by the method for producing a resin particle dispersion according to any one of claims 1 to 3, and aggregating at least the resin particles in the obtained resin particle dispersion containing the resin particles 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:

Images