Method for producing toner for electrostatic charge image development

Abstract

To provide a method for producing a toner for electrostatic charge image development which is excellent in image unevenness suppression property.SOLUTION: A method for producing a toner for electrostatic charge image development includes a step of aggregating particles containing binder resin particles in a dispersion liquid and forming aggregated particles, and a step of heating the aggregated particles and raising its temperature, and fusing the aggregated particles, wherein an agitation Reynolds number in agitation of the dispersion liquid in the fusion step is 5.0×104 or more and 1.0×106 or less.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] Methods for visualizing image information, such as electrophotography, are currently used in various fields. In electrophotography, an electrostatic image is formed as image information on the surface of an image carrier by charging and forming an electrostatic image. Then, a toner image is formed on the surface of the image carrier by a developer containing a toner, and the toner image is transferred to a recording medium, and then fixed to the recording medium. Through these steps, the image information is visualized as an image.

[0003] For example, Patent Document 1 discloses a method for producing a toner for developing electrostatic images, the method including: an aggregating agent mixing step of adding an aggregating agent to a dispersion liquid containing binder resin particles while circulating the dispersion liquid containing binder resin particles between a stirring tank and a disperser that applies mechanical shearing force, and mixing the aggregating agent into the dispersion liquid containing binder resin particles; an aggregating step of heating the dispersion liquid to form aggregating particles after reducing the viscosity of the dispersion liquid that has undergone the aggregating agent mixing step; and a coalescing step of heating the dispersion liquid containing the aggregating particles to fuse and coalesce the aggregating particles to form toner particles.

[0004] Patent Document 2 describes a method for producing toner particles, which includes a granulation step of dispersing toner raw materials in an aqueous medium using a stirring means. The stirring means is a stirring device equipped with at least a rotating shaft and agitating blades, and the angles α (°) between adjacent agitating blades on a plane perpendicular to the rotating shaft and centered on the rotating shaft are as follows: 100≦α≦140 The stirring blade diameter d (m) and the inner diameter D (m) of the granulation vessel in which the granulation step is performed are 0.05≦d / D≦0.35, and further, When the peripheral speed of the impeller is A (m / s), 20≦A≦40 A method for producing toner particles is disclosed, which is characterized in that the toner particles have the following relationship:

[0005] In addition, Patent Document 3 describes a shear rate of 10 s -1 The viscosity is 1 Pa.s or more when the following formula is met: Thixotropy index = (shear rate 1s -1 Viscosity at shear rate 10s -1 Viscosity at In a toner manufacturing method using an emulsion aggregation method in which an aggregate liquid having a thixotropy index of 7 or more defined by the above is stirred, the aggregate liquid is stirred with a multi-shaft agitator blade at a shear rate of 10 s -1 The following parts are less than 50% by volume, 400s -1 A method for producing a toner is disclosed, which is characterized by including an aggregation step in which an agitating blade is rotated at a shear rate of 1% by volume or less. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2022-145174 A [Patent Document 2] JP 2008-268313 A [Patent Document 3] JP 2019-8042 A Summary of the Invention [Problem to be solved by the invention]

[0007] The object of the present invention is to provide a method for producing a dispersion liquid which comprises a step of aggregating particles including binder resin particles in the dispersion liquid to form aggregated particles, and a step of fusing the aggregated particles by heating the aggregated particles, the method comprising the steps of: 4 Less than or 1.0 x 10 6 The present invention provides a method for producing a toner for developing electrostatic images, which is superior in suppressing image unevenness compared to a case where the toner is more highly viscous than the case where the toner is more highly viscous. [Means for solving the problem]

[0008] Means for solving the above problems include the following aspects. <1> The method includes a step of aggregating particles including binder resin particles in a dispersion liquid to form aggregated particles, and a step of fusing the aggregated particles by heating the aggregated particles, and the Reynolds number of stirring in the dispersion liquid during the fusing step is 5.0×10 4 Above 1.0×10 6 A method for producing a toner for developing an electrostatic image, comprising: <2> In the fusion step, when the viscosity of the binder resin of the binder resin particles is η and the temperature after the heating is T, the following relationship is satisfied: 1,000 Pa s≦η(T)≦4,500 Pa s <1> 2. A method for producing the toner for developing electrostatic images according to claim 1 . <3> In the fusion step, when the viscosity of the binder resin of the binder resin particles is η and the temperature after the heating is T, the following relationship is satisfied: 2,000 Pa s≦η(T)≦4,500 Pa s <2> 2. A method for producing the toner for developing electrostatic images according to claim 1 . <4> The ratio of the crystalline polyester resin contained in the binder resin in the obtained toner particles is 15% by mass or more and 50% by mass or less. <1> ~ <3> 13. A method for producing the toner for developing electrostatic images according to claim 12. <5> The ratio of the crystalline polyester resin contained in the binder resin in the obtained toner particles is 20% by mass or more and 40% by mass or less. <4> 2. A method for producing the toner for developing electrostatic images according to claim 1 . <6> The solid content of the dispersion in the fusion step is 8% by mass or more and 30% by mass or less. <1> ~ <5> 13. A method for producing the toner for developing electrostatic images according to claim 12. <7> The temperature after the heating in the fusion step is equal to or higher than the glass transition temperature of the binder resin (glass transition temperature of the binder resin + 40° C.) <1> ~ <6> 13. A method for producing the toner for developing electrostatic images according to claim 12. <8> The stirring Reynolds number is 6.0×10 4 Above 9.0×10 5 Is less than or equal to <1> ~ <7> 13. A method for producing the toner for developing electrostatic images according to claim 12. <9> In the fusion step, an acidic aqueous solution is added. <1> ~ <8> 13. A method for producing the toner for developing electrostatic images according to claim 12. <10> The pH in the fusion step is 7 or more and 10 or less. <1> ~ <9> 13. A method for producing the toner for developing electrostatic images according to claim 12. <11> A stirring device equipped with a propeller-type, anchor-type or paddle-type stirring blade and a rotating shaft is used to stir the dispersion during the fusion step. <1> ~ <10> 13. A method for producing the toner for developing electrostatic images according to claim 12. Effect of the Invention

[0009] <1> , <9> or <11> According to the present invention, the method includes a step of aggregating particles including binder resin particles in a dispersion liquid to form aggregated particles, and a step of fusing the aggregated particles by heating the aggregated particles, and the Reynolds number of stirring in the stirring of the dispersion liquid during the fusing step is 5.0×10 4 Less than or 1.0 x 10 6 The present invention provides a method for producing a toner for developing electrostatic images, which is excellent in suppressing image unevenness compared to the case where the toner is more than 100%. <2> According to the present invention, there is provided a method for producing a toner for developing electrostatic images, which is superior in suppressing image unevenness compared to when η(T) is less than 1,000 Pa·s or exceeds 4,500 Pa·s. <3> According to the present invention, there is provided a method for producing a toner for developing electrostatic images, which is superior in suppressing image unevenness compared to when the η(T) is less than 2,000 Pa·s or exceeds 4,500 Pa·s. <4> According to the present invention, there is provided a method for producing a toner for developing electrostatic images, which has excellent low-temperature fixing properties and suppresses image unevenness, compared to when the proportion of crystalline polyester resin contained in the binder resin in the obtained toner particles is less than 15% by mass or more than 50% by mass. <5> According to the present invention, there is provided a method for producing a toner for developing electrostatic images, which has excellent low-temperature fixing properties and suppresses image unevenness, compared to when the proportion of crystalline polyester resin contained in the binder resin in the obtained toner particles is less than 20% by mass or more than 40% by mass. <6> According to the present invention, there is provided a method for producing a toner for developing electrostatic images, which is superior in suppressing image unevenness compared to when the solid content of the dispersion in the fusion step is less than 8% by mass or more than 30% by mass. <7> According to the present invention, there is provided a method for producing a toner for developing electrostatic images, which is superior in suppressing image unevenness compared to a case in which the temperature of the dispersion liquid in the fusion step is lower than the glass transition temperature of the binder resin or higher than (the glass transition temperature of the binder resin + 40°C). <8> According to the invention, the stirring Reynolds number is 6.0×10 4 Less than or equal to 9.0 x 10 5 The present invention provides a method for producing a toner for developing electrostatic images, which is more excellent in suppressing image unevenness than when the toner is more than 100%. <10> According to the present invention, there is provided a method for producing a toner for developing electrostatic images, which is more excellent in suppressing image unevenness than when the pH in the fusing step is less than 6 or more than 10. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of an image forming apparatus used in the present embodiment. [Diagram 2] FIG. 2 is a schematic diagram illustrating an example of a process cartridge used in the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described in detail. In addition, in numerical ranges described in stages, the upper limit or lower limit value described in a certain numerical range may be replaced with the upper limit or lower limit value of another numerical range described in stages. In addition, in a numerical range, the upper limit or lower limit described in a certain numerical range may be replaced with a value shown in the examples. When a plurality of substances corresponding to each component are present in the composition, the amount of each component in the composition means the total amount of the plurality of substances present in the composition, unless otherwise specified. 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.

[0012] (Method of manufacturing toner for developing electrostatic images) The method for producing a toner for developing an electrostatic image according to the present embodiment includes a step of aggregating particles including binder resin particles in a dispersion liquid to form aggregated particles, and a step of fusing the aggregated particles by heating the aggregated particles to a higher temperature, and the agitation Reynolds number in stirring the dispersion liquid during the fusing step is 5.0×10 4 Above 1.0×10 6 The following is the result.

[0013] The electrostatic image developing toner according to this embodiment is a toner produced by the method for producing the electrostatic image developing toner according to this embodiment.

[0014] Toner manufacturing methods include a wet manufacturing method, in which, for example, binder resin particles, release agent particles, etc. are aggregated using an aggregating agent such as a metal salt, and the resulting aggregated particles are heated to fuse them. Conventional toner manufacturing methods that produce toner by agglomeration and fusion of particles have had problems in that particles come into contact with each other, such as agglomerated particles, due to agitation, and stress due to agitation; more specifically, stress due to an increase in the number of particle contacts and an increase in the particle approach speed, as well as stress due to collisions with baffles, etc., causing particles to come into contact with each other and generating coarse powder. In the method for producing the toner for developing electrostatic images according to the present embodiment, the stirring Reynolds number in stirring the dispersion liquid during the fusing step is 5.0×10 4 Above 1.0×10 6 It is presumed that by satisfying the following conditions, a toner for developing electrostatic images having excellent suppression of image unevenness can be obtained, as will be described below. The stirring Reynolds number is an index that represents the relationship between the inertial force and the viscous force of a dispersion liquid during stirring. If the stirring Reynolds number is too high, the inertial force in the dispersion is strong, so that the contact between particles such as aggregated particles and toner particles and the wall surface or baffle plate increases, and the particles are crushed and aggregated by the impact, resulting in the generation of aggregates. Moreover, if the stirring Reynolds number is too low, the viscosity of the dispersion liquid is strong, and the particles are insufficiently dispersed, resulting in increased contact with each other and the formation of aggregates. Conventionally, the stirring Reynolds number was often higher than the above range. By setting the stirring Reynolds number in the stirring of the dispersion during the fusion step within the above range, the dispersion is brought into an appropriately stirred and mixed state, and the generation of agglomerates as described above is suppressed.

[0015] Each step will be described in detail below.

[0016] <Step of forming aggregated particles> The method for producing the toner for developing electrostatic images according to the present embodiment includes a step of aggregating particles containing binder resin particles in a dispersion liquid to form aggregated particles.

[0017] The dispersion liquid may contain not only binder resin particles but also particles such as colorant particles and releasing agent particles, if necessary. The binder resin particles preferably contain amorphous resin particles and crystalline resin particles. The binder resin in the binder resin particles is not particularly limited, but is preferably a polyester resin. In the method for producing a toner for developing electrostatic images according to the present embodiment, the ratio of the crystalline resin contained in the binder resin in the obtained toner particles is not limited. From the viewpoints of suppressing the generation of coarse particles and low-temperature fixability, however, it is preferable that the ratio of the crystalline resin contained in the binder resin in the obtained toner particles is 15% by mass or more and 50% by mass or less, and more preferably 20% by mass or more and 40% by mass or less. In the method for producing a toner for developing electrostatic images according to the present embodiment, the proportion of the crystalline polyester resin contained in the binder resin in the obtained toner particles is not limited. From the viewpoint of suppressing the generation of coarse particles, however, the proportion of the crystalline polyester resin contained in the binder resin in the obtained toner particles and the low-temperature fixability are preferably from 15% by mass to 50% by mass, and more preferably from 20% by mass to 40% by mass.

[0018] The dispersion liquid is suitably prepared, for example, by mixing an amorphous resin particle dispersion liquid, a crystalline resin particle dispersion liquid, a colorant particle dispersion liquid, and a release agent particle dispersion liquid. In the dispersion liquid, it is preferable to hetero-aggregate, for example, amorphous resin particles, crystalline resin particles, colorant particles, and release agent particles to form aggregated particles containing the amorphous resin particles, the crystalline resin particles, the colorant particles, and the release agent particles and having a diameter close to that of the target toner particles.

[0019] Specifically, for example, an aggregating agent is added to the dispersion liquid, the pH of the dispersion liquid is adjusted to be acidic (e.g., pH 2 or more and 5 or less), a dispersion stabilizer is added as necessary, and then the mixture is heated to a temperature of 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 liquid are aggregated to form aggregated particles. In the step of forming the aggregated particles, for example, the aggregating agent may be added to the dispersion at room temperature (e.g., 25°C) while stirring the dispersion with a rotary shear homogenizer, the pH of the dispersion may be adjusted to an acidic state (e.g., pH 2 or more and 5 or less), and a dispersion stabilizer may be added as necessary, followed by the heating.

[0020] Examples of the flocculant include a surfactant having a polarity opposite to that of the surfactant used as the dispersant added to the dispersion liquid, 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 the surfactant used is reduced and the charging characteristics are 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.

[0021] 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, for example, oxycarboxylic acid such as 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, relative to 100 parts by mass of the amorphous resin particles.

[0022] The preferred embodiments of each of the components contained in the toner particles, such as the binder resin, the release agent, and the colorant, will be described below.

[0023] <Fusing process> The method for producing the toner for developing an electrostatic image according to the present embodiment includes a step of heating and fusing the aggregated particles, and the Reynolds number of stirring in stirring the dispersion liquid during the fusing step is 5.0×10 4 Above 1.0×10 6 The following is the result.

[0024] The stirring Reynolds number in stirring the dispersion during the fusion step is 5.0×10 4 Above 1.0×10 6 From the viewpoint of suppressing image unevenness, it is 6.0×10 4 Above 9.0×10 5 It is preferable that the value is less than 7.0×10 4 Above 5.0×10 5 It is more preferable that:

[0025] In this embodiment, the stirring Reynolds number is calculated by the following formula. The length of the impeller is l [m], the tip speed of the impeller is v [m / s], and the specific gravity of the dispersion is ρ [kg / m 3 ] and the viscosity of the dispersion is μ [Pa s], the Reynolds number Re can be calculated using the following equation. Re=ρνl / μ

[0026] In the present embodiment, the fusion process is performed from the point at which the temperature of the dispersion is raised to or above the glass transition temperature of the binder resin and then the stirring Reynolds number is set in the range until the dispersion is cooled to a temperature below the glass transition temperature of the binder resin. In the fusion process, from the viewpoint of suppressing image unevenness, it is preferable to maintain the stirring Reynolds number in the above range for 10 minutes or more, it is more preferable to maintain the stirring Reynolds number in the above range for 20 minutes or more, it is even more preferable to maintain the stirring Reynolds number in the above range for 30 minutes or more and 600 minutes or less, and it is particularly preferable to maintain the stirring Reynolds number in the above range for 30 minutes or more and 300 minutes or less. In addition, in the fusion step, from the viewpoint of suppressing image unevenness, after the temperature of the dispersion liquid is raised to a temperature equal to or higher than the glass transition temperature of the binder resin, it is preferable to set the stirring Reynolds number within the range of 30 minutes, it is more preferable to set the stirring Reynolds number within the range of 10 minutes, and it is particularly preferable to set the stirring Reynolds number within the range of 5 minutes.

[0027] In the method for producing the toner for developing electrostatic images according to the present embodiment, in the fusion step, when the viscosity of the binder resin of the binder resin particles is η and the temperature after the temperature increase is T, from the viewpoint of suppressing image unevenness, it is preferable that 1,000 Pa s≦η(T)≦4,500 Pa s is satisfied, and it is more preferable that 2,000 Pa s≦η(T)≦4,500 Pa s is satisfied. Here, η(T) represents the viscosity at temperature T.

[0028] In the present embodiment, the viscosity of the binder resin is measured using a high-speed flow tester CFT-500 (manufactured by Shimadzu Corporation), with the die hole diameter set to 1.0 mm and the pressure load set to 10 kgf / cm. 2 Under the conditions of a heating rate of 7°C / min and a starting temperature of 60°C, 3 The viscosity (melt viscosity) of the sample is determined when it is melted and poured out. The viscosity measured at the temperature T after the temperature increase in the fusion step is η(T).

[0029] The solid content of the dispersion in the fusion step is preferably from 8% by mass to 30% by mass, and more preferably from 10% by mass to 25% by mass, from the viewpoint of suppressing image unevenness.

[0030] In the fusion step, 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 binder resin particles, preferably equal to or higher than the glass transition temperature of the binder resin particles (glass transition temperature of the binder resin particles + 40°C), more preferably equal to or higher than (glass transition temperature of the binder resin particles + 10°C) (glass transition temperature of the binder resin particles + 30°C), to fuse the aggregated particles and form toner particles.

[0031] In the fusion step, the peripheral speed of a stirring member such as a stirring blade in stirring the dispersion liquid is preferably 0.3 m / s or more and 5.0 m / s or less, more preferably 0.5 m / s or more and 4.0 m / s or less, and particularly preferably 1.0 m / s or more and 3.0 m / s or less, from the viewpoint of suppressing image unevenness.

[0032] In the fusion step, the pH of the dispersion is preferably from 6 to 10, more preferably from 6.5 to 9, and particularly preferably from 7.0 to 8.5, from the viewpoint of suppressing image unevenness. In the fusion step, it is preferable to add an acidic aqueous solution to the dispersion from the viewpoint of pH adjustment. In terms of particle formability and suppression of image unevenness, the addition of the acidic aqueous solution in the fusion step is preferably performed after raising the temperature to a temperature equal to or higher than the glass transition temperature of the binder resin in the binder resin particles, and more preferably after setting the stirring Reynolds number in the range described above. The acidic aqueous solution may be an aqueous solution of an inorganic acid or an aqueous solution of an organic acid, but is preferably an aqueous solution of an inorganic acid, and more preferably an aqueous solution of nitric acid.

[0033] <Mixing device> The stirring device used in the step of forming the agglomerated particles and the step of fusing the particles is not particularly limited, and any known stirring device can be used. Preferred examples of the stirring device include stirring devices having stirring blades and a rotating shaft, and more preferred examples of the stirring device include stirring devices having propeller-type, anchor-type, or paddle-type stirring blades and a rotating shaft. The stirring device is preferably equipped with a granulation vessel (stirring tank) having a temperature control mechanism such as a jacket. The stirring blade is not particularly limited, and examples thereof include propeller-type, anchor-type, paddle-type, turbine-type, etc. Among them, from the viewpoint of suppressing image unevenness, propeller-type, anchor-type, or paddle-type stirring blades are preferred.

[0034] In the stirring device, when the stirring blade diameter is d (m) and the granulation vessel inner diameter is D (m), the value of d / D is preferably 0.3 to 0.8, more preferably 0.5 to 0.7. Furthermore, in the stirring device, the stirring blade diameter d is preferably 0.2 m or more, and more preferably 0.3 m or more, from the viewpoint of further exerting the effects of this embodiment.

[0035] The method for producing the toner for developing an electrostatic image according to the present embodiment may further include known steps other than the step of forming the aggregated particles and the step of fusing the aggregated particles. Specifically, for example, the following steps may be mentioned. The method for producing the toner for developing electrostatic images according to the embodiment preferably includes a preparation step of preparing toner particles containing an amorphous resin.

[0036] Specifically, for example, the method for producing the toner for developing electrostatic images according to the present embodiment includes the following steps: A step of preparing an amorphous resin particle dispersion liquid in which amorphous resin particles are dispersed, and a crystalline resin particle dispersion liquid in which crystalline resin particles are dispersed (a resin particle dispersion preparation step); forming the aggregated particles; a step of mixing the aggregated particle dispersion liquid with an amorphous resin particle dispersion liquid after obtaining the aggregated particles and aggregating the aggregated particles so that the amorphous resin particles are attached to the surfaces of the aggregated particles to form second aggregated particles (second aggregated particle step); a step of adjusting the pH of the dispersion to stop the progress of aggregation (aggregation stopping step); The method preferably includes the step of fusing.

[0037] 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 necessary. Of course, additives other than the colorant and the release agent may be used.

[0038] -Resin particle dispersion preparation process- First, in addition to each resin particle dispersion liquid (amorphous resin particle dispersion liquid and crystalline resin particle dispersion liquid) in which each resin particle that will become the binder resin is dispersed, for example, a colorant particle dispersion liquid in which colorant particles are dispersed and a release agent particle dispersion liquid in which release agent particles are dispersed are prepared.

[0039] Here, the resin particle dispersion liquid is prepared, for example, by dispersing resin particles in a dispersion medium with the aid of a surfactant.

[0040] The dispersion medium used in the resin particle dispersion liquid is, for example, an aqueous medium. Examples of the aqueous medium include water such as distilled water and ion-exchanged water, alcohols, etc. These may be used alone or in combination of two or more kinds.

[0041] Examples of the surfactant include anionic surfactants such as sulfate salts, sulfonates, phosphates, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, anionic surfactants and cationic surfactants are particularly preferred. The nonionic surfactants may be used in combination with anionic surfactants or cationic surfactants. The surfactant may be used alone or in combination of two or more kinds.

[0042] In the resin particle dispersion, examples of the method for dispersing the resin particles in the dispersion medium include general dispersion methods using, for example, a rotary shear type homogenizer, a ball mill having a media, a sand mill, a dyno mill, etc. Depending on the type of resin particles, the resin particles may be dispersed in the resin particle dispersion using, for example, a phase inversion emulsification method. The phase inversion emulsification method is a method in which the resin to be dispersed is dissolved in a hydrophobic organic solvent in which the resin is soluble, a base is added to the organic continuous phase (O phase) to neutralize it, and then an aqueous medium (W phase) is added to effect conversion of the resin from W / O to O / W (so-called phase inversion), resulting in a discontinuous phase, and the resin is dispersed in particulate form in the aqueous medium.

[0043] The volume average particle size of the resin particles dispersed in the resin particle dispersion is, for example, preferably from 0.01 μm to 1 μm, more preferably from 0.08 μm to 0.8 μm, and even more preferably from 0.1 μm to 0.6 μm. The volume average particle size of the resin particles is measured by using a particle size distribution obtained by measurement using a laser diffraction particle size distribution measuring device (e.g., LA-700 manufactured by Horiba, Ltd.), subtracting the cumulative distribution from the small particle size side for the volume of the divided particle size range (channel), and measuring the particle size at which the cumulative distribution is 50% of all particles as the volume average particle size D50v. The volume average particle sizes of particles in other dispersions are also measured in the same manner.

[0044] The content of the resin particles in the resin particle dispersion is, for example, preferably from 5% by mass to 50% by mass, and more preferably from 10% by mass to 40% by mass.

[0045] In addition, for example, a colorant particle dispersion and a release agent particle dispersion are also prepared in the same manner as the resin particle dispersion. That is, the volume average particle size, dispersion medium, dispersion method, and particle content of the particles in the resin particle dispersion are the same for the colorant particles dispersed in the colorant particle dispersion and the release agent particles dispersed in the release agent particle dispersion.

[0046] -Second agglomerated particle formation process- After obtaining the aggregated particle dispersion in which the aggregated particles are dispersed, the aggregated particle dispersion and the amorphous resin particle dispersion are mixed together.

[0047] Then, in the dispersion liquid in which the aggregated particles and the amorphous resin particles are dispersed, the amorphous resin particles are aggregated on the surfaces of the aggregated particles. Specifically, for example, in the step of forming the aggregated particles, when the aggregated particles reach a target particle size, a dispersion of amorphous resin particles is added to a dispersion of the aggregated particles, and the dispersion is heated at a temperature equal to or lower than the glass transition temperature of the amorphous resin particles. Then, the pH of the dispersion is adjusted to stop the progress of aggregation (aggregation stopping step).

[0048] After the fusion step, the toner particles formed in the solution are subjected to a known washing step, a solid-liquid separation step, and a drying step 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 charge. In addition, the solid-liquid separation step is not particularly limited, but it is preferable to carry out suction filtration, pressure filtration, etc. from the viewpoint of productivity. In addition, in the drying step, there is no particular limit to the method, but it is preferable to carry out freeze drying, air flow drying, fluidized drying, vibration type fluidized drying, etc. from the viewpoint of productivity.

[0049] The method for producing the toner for developing electrostatic images according to the present embodiment preferably includes a step of externally adding an external additive to the obtained toner particles. The external addition may be carried out, for example, by using a V blender, a Henschel mixer, a Loedige mixer, etc. Furthermore, if necessary, coarse particles of the toner may be removed using a vibration sifter, a wind sifter, etc.

[0050] Hereinafter, each component contained in the toner for developing electrostatic images obtained by the method for producing the toner for developing electrostatic images according to this embodiment will be described in detail.

[0051] <Binding resin> The binder resin preferably contains an amorphous resin, and more preferably contains an amorphous resin and a crystalline resin from the viewpoints of image strength and suppression of density unevenness in the obtained image. That is, in the step of forming the aggregated particles, it is more preferable that the binder resin particles contain an amorphous resin particle and a crystalline resin particle. The toner particles preferably contain an amorphous resin. Furthermore, the toner particles are preferably core-shell type toner particles.

[0052] Here, the term "amorphous resin" refers to a resin that, in a thermal analysis measurement using differential scanning calorimetry (DSC), has only a stepwise endothermic change rather than a clear endothermic peak, is a solid at room temperature, and is thermoplasticized at a temperature equal to or higher than the glass transition temperature. On the other hand, a crystalline resin refers to a resin that has 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 an endothermic peak is within 10°C when measured at a heating rate of 10°C / min, and an amorphous resin means a resin whose half-width exceeds 10°C or a resin in which no clear endothermic peak is observed.

[0053] The amorphous resin will now be described. Examples of the amorphous resin include known amorphous resins such as amorphous polyester resin, amorphous vinyl resin (e.g., styrene acrylic resin, etc.), epoxy resin, polycarbonate resin, polyurethane resin, etc. Among these, from the viewpoint of suppressing uneven density and suppressing white spots in the obtained image, amorphous polyester resin and amorphous vinyl resin (particularly styrene acrylic resin) are preferred, and amorphous polyester resin is 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.

[0054] The amorphous polyester resin may be, for example, a condensation polymer of a polyvalent carboxylic acid and a polyhydric alcohol. As the amorphous polyester resin, a commercially available product or a synthesized product may be used.

[0055] Examples of polyvalent carboxylic 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, sebacic acid, etc.), alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, etc.), anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). Among these, aromatic dicarboxylic acids are preferred as the polyvalent carboxylic acid. The polyvalent carboxylic 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 (e.g., carbon number 1 to 5) alkyl esters thereof. The polyvalent carboxylic acids may be used alone or in combination of two or more kinds.

[0056] 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 the trihydric or higher polyhydric alcohol include glycerin, trimethylolpropane, and pentaerythritol. The polyhydric alcohols may be used alone or in combination of two or more kinds.

[0057] The amorphous polyester resin is obtained by a known manufacturing method. Specifically, for example, the polymerization temperature is set to 180°C or more and 230°C or less, the reaction system is depressurized as necessary, and the reaction is carried out while removing water and alcohol generated during condensation. If the raw material monomer is not dissolved or compatible at the reaction temperature, a high-boiling point solvent may be added as a dissolution aid to dissolve it. In this case, the polycondensation reaction is carried out while distilling off the dissolution aid. If a monomer with poor compatibility is present in the copolymerization reaction, it is recommended that the monomer with poor compatibility is condensed in advance with the acid or alcohol to be polycondensed with the monomer and then polycondensed with the main component.

[0058] The proportion of the amorphous resin in the total binder resin is preferably 60% by mass or more and 98% by mass or less, more preferably 65% ​​by mass or more and 95% by mass or less, and even more preferably 70% by mass or more and 90% by mass or less.

[0059] The characteristics of the amorphous resin will be described. The glass transition temperature (Tg) of the amorphous 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 determined from a DSC curve obtained by differential scanning calorimetry (DSC), more specifically, from the "extrapolated glass transition onset temperature" described in the method for determining glass transition temperature in JIS K 7121-1987 "Method for measuring transition temperature of plastics."

[0060] The weight average molecular weight (Mw) of the amorphous 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 amorphous resin is preferably 2,000 or more and 100,000 or less. The molecular weight distribution Mw / Mn of the amorphous 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). The molecular weight measurement by GPC is performed using a Tosoh Corporation GPC·HLC-8120GPC as the measuring device, a Tosoh Corporation TSKgel SuperHM-M (15 cm) column, and tetrahydrofuran (THF) solvent. The weight average molecular weight and number average molecular weight are calculated from the measurement results using a molecular weight calibration curve created with a monodisperse polystyrene standard sample. From the viewpoint of suppressing the generation of coarse particles, it is preferable to use, as the amorphous polyester resin, a polyester resin having a weight average molecular weight of 5,000 or more and 20,000 or less in combination with a polyester resin having a weight average molecular weight of more than 20,000 and 1,000,000 or less, it is more preferable to use a polyester resin having a weight average molecular weight of 7,000 or more and 20,000 or less in combination with a polyester resin having a weight average molecular weight of more than 20,000 and 500,000 or less, and it is particularly preferable to use a polyester resin having a weight average molecular weight of 7,000 or more and 20,000 or less in combination with a polyester resin having a weight average molecular weight of more than 20,000 and 100,000 or less.

[0061] The crystalline resin will now be described. Examples of the crystalline resin include known crystalline resins such as crystalline polyester resins and crystalline vinyl resins (e.g., polyalkylene resins, long-chain alkyl (meth)acrylate resins, etc.). Among these, crystalline polyester resins are preferred from the viewpoint of suppressing uneven density and white spots in the resulting image.

[0062] The crystalline polyester resin may be, for example, a polycondensate of a polyvalent carboxylic acid and a polyhydric alcohol. As the crystalline polyester resin, a commercially available product or a synthesized product may be used. Since the crystalline polyester resin easily forms a crystalline structure, a polycondensation product using a straight-chain aliphatic polymerizable monomer is preferable to a polymerizable monomer having an aromatic ring.

[0063] Examples of polyvalent carboxylic acids include aliphatic dicarboxylic acids (e.g., oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, etc.), anhydrides thereof, and lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). The polyvalent carboxylic 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 carboxylic acid include aromatic carboxylic acids (e.g., 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, etc.), their anhydrides, and their lower (e.g., carbon number 1 to 5) alkyl esters. As the polyvalent carboxylic acid, a dicarboxylic acid having a sulfonic acid group and a dicarboxylic acid having an ethylenic double bond may be used in combination with these dicarboxylic acids. The polyvalent carboxylic acids may be used alone or in combination of two or more kinds.

[0064] Examples of polyhydric alcohols include aliphatic diols (for example, straight-chain aliphatic diols having 7 to 20 carbon atoms in the main chain). Examples of aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,14-eicosanedecanediol. Among these, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferred as aliphatic diols. The polyhydric alcohol may be a trihydric or higher alcohol having a crosslinked or branched structure in combination with the diol. Examples of the trihydric or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol. The polyhydric alcohols may be used alone or in combination of two or more kinds.

[0065] The polyhydric alcohol may have an aliphatic diol content of 80 mol % or more, and preferably 90 mol % or more.

[0066] The melting temperature of the crystalline polyester resin is preferably 50°C or higher and 100°C or lower, more preferably 55°C or higher and 90°C or lower, and even more preferably 60°C or higher and 85°C or lower. The melting temperature of the crystalline polyester resin is determined from a DSC curve obtained by differential scanning calorimetry (DSC) based on the "melting peak temperature" described in the method for determining melting temperature in JIS K7121:1987 "Method for measuring transition temperature of plastics."

[0067] The weight average molecular weight (Mw) of the crystalline polyester resin is preferably 6,000 or more and 35,000 or less.

[0068] The crystalline polyester resin can be obtained, for example, by a known production method, like the amorphous polyester resin.

[0069] As the crystalline polyester resin, a polymer of an α,ω-linear aliphatic dicarboxylic acid and an α,ω-linear aliphatic diol is preferred from the viewpoint of easily forming a crystal structure and having good compatibility with the amorphous polyester resin, thereby improving the fixability of the image.

[0070] The α,ω-linear aliphatic dicarboxylic acid is preferably an α,ω-linear aliphatic dicarboxylic acid in which the alkylene group connecting the two carboxy groups has 3 or more and 14 or less carbon atoms, more preferably the alkylene group has 4 or more and 12 or less carbon atoms, and even more preferably the alkylene group has 6 or more and 10 or less carbon atoms. Examples of α,ω-linear aliphatic dicarboxylic acids include succinic acid, glutaric acid, adipic acid, 1,6-hexanedicarboxylic acid (commonly known as suberic acid), 1,7-heptanedicarboxylic acid (commonly known as azelaic acid), 1,8-octanedicarboxylic acid (commonly known as sebacic acid), 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid. Of these, 1,6-hexanedicarboxylic acid, 1,7-heptanedicarboxylic acid, 1,8-octanedicarboxylic acid, and 1,10-decanedicarboxylic acid are preferred. The α,ω-linear aliphatic dicarboxylic acids may be used alone or in combination of two or more kinds.

[0071] The α,ω-linear aliphatic diol is preferably an α,ω-linear aliphatic diol in which the alkylene group connecting the two hydroxy groups has 3 to 14 carbon atoms, more preferably the alkylene group has 4 to 12 carbon atoms, and further preferably the alkylene group has 6 to 10 carbon atoms. Examples of the α,ω-linear aliphatic diol include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,14-tetradecanediol, and 1,18-octadecanediol. Of these, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferred. The α,ω-linear aliphatic diols may be used alone or in combination of two or more kinds.

[0072] As the polymer of an α,ω-linear aliphatic dicarboxylic acid and an α,ω-linear aliphatic diol, from the viewpoint of easily forming a crystal structure and having good compatibility with an amorphous polyester resin, thereby improving the fixability of an image, a polymer of at least one selected from the group consisting of 1,6-hexanedicarboxylic acid, 1,7-heptanedicarboxylic acid, 1,8-octanedicarboxylic acid, 1,9-nonanedicarboxylic acid, and 1,10-decanedicarboxylic acid and at least one selected from the group consisting of 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol is preferred, and among these, a polymer of 1,10-decanedicarboxylic acid and 1,6-hexanediol is more preferred.

[0073] Other binder resins Examples of the binder resin include homopolymers of monomers such as ethylenically unsaturated nitriles (e.g., acrylonitrile, methacrylonitrile, etc.), vinyl ethers (e.g., vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (e.g., vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.) and olefins (e.g., ethylene, propylene, butadiene, etc.), and copolymers of two or more of these monomers. Other examples of the binder resin include non-vinyl resins such as epoxy 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 coexistence of these. These binder resins may be used alone or in combination of two or more kinds.

[0074] The content of the binder resin is preferably from 40% by mass to 95% by mass, more preferably from 50% by mass to 90% by mass, and even more preferably from 60% by mass to 85% by mass, based on the total mass of the toner particles.

[0075] -Release agent- Examples of the release agent 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 montan acid esters. The release agent is not limited to these.

[0076] As the release agent, from the viewpoints of suppressing uneven density and white voids in the obtained image and having good compatibility with the amorphous polyester resin, thereby improving the fixability of the image, an ester wax is preferred, and an ester wax of a higher fatty acid having from 10 to 30 carbon atoms and a monovalent or polyvalent alcohol component having from 1 to 30 carbon atoms is more preferred.

[0077] The ester wax is a wax having an ester bond. The ester wax may be any of a monoester, diester, triester, and tetraester, and any known natural or synthetic ester wax can be used. Examples of ester waxes include ester compounds of higher fatty acids (such as fatty acids having 10 or more carbon atoms) and monohydric or polyhydric aliphatic alcohols (such as aliphatic alcohols having 8 or more carbon atoms), and have a melting temperature of 60°C or higher and 110°C or lower (preferably 65°C or higher and 100°C or lower, more preferably 70°C or higher and 95°C or lower). Examples of ester waxes include ester compounds of higher fatty acids (caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, behenic acid, oleic acid, etc.) and alcohols (monohydric alcohols such as methanol, ethanol, propanol, isopropanol, butanol, capryl alcohol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol, etc.; polyhydric alcohols such as glycerin, ethylene glycol, propylene glycol, sorbitol, pentaerythritol, etc.). Specific examples include carnauba wax, rice wax, candelilla wax, jojoba oil, Japan wax, beeswax, privet wax, lanolin, and montanic acid ester wax.

[0078] 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 of the release agent is determined from a DSC curve obtained by differential scanning calorimetry (DSC) based on the "melting peak temperature" described in the method for determining melting temperature in JIS K7121:1987 "Method for measuring transition temperature of plastics."

[0079] The content of the release agent is preferably from 1% by mass to 20% by mass, and more preferably from 5% by mass to 15% by mass, based on the total mass of the toner particles.

[0080] -Coloring agent- In the aggregating step, it is preferable that the dispersion liquid further contains colorant particles. 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 tetrahydrofuran. Examples of the pigments include phosphorus blue, chalcoil blue, methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, and malachite green oxalate, as well as 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.

[0081] The colorant may be surface-treated as necessary, or may be used in combination with a dispersant. In addition, a plurality of types of colorants may be used in combination.

[0082] The content of the colorant is, for example, preferably from 1% by mass to 30% by mass, and more preferably from 3% by mass to 15% by mass, based on the total mass of the toner particles.

[0083] -Other additives- Examples of other additives include well-known additives such as magnetic materials, charge control agents, inorganic powders, etc. These additives are contained in the toner particles as internal additives.

[0084] -Characteristics of toner particles, etc.- The toner particles may be toner particles having a so-called core-shell structure (core-shell type particles) composed of a core (core particle) and a coating layer (shell layer) that coats the core. The toner particles having a core-shell structure may be composed of, for example, a core containing a binder resin and, if necessary, a colorant and a release agent, and a coating layer containing a binder resin. In the case of toner particles having a core-shell structure, the average thickness of the shell layer is preferably 120 nm or more, more preferably 130 nm or more, and even more preferably 140 nm or more, from the viewpoint of suppressing deformation of the toner particles, and is preferably 550 nm or less, more preferably 500 nm or less, and even more preferably 400 nm or less.

[0085] The average thickness of the shell layer is measured by the following method. Toner particles are embedded in epoxy resin, sliced ​​using a diamond knife or the like, and the slices are stained with osmium tetroxide or ruthenium tetroxide in a desiccator. The stained slices are observed under a scanning electron microscope (SEM). Ten toner particle cross sections are randomly selected from the SEM images, and the shell layer thickness is measured at 20 points per toner particle, the average value is calculated, and the average value of the 10 toner particles is regarded as the average thickness.

[0086] Toner volume average particle size (D 50v ) is preferably from 2 μm to 10 μm, and more preferably from 4 μm to 8 μm.

[0087] The volume average particle size of the toner is measured using a Coulter Multisizer II (manufactured by Beckman Coulter, Inc.), and the electrolyte is measured using an ISOTON-II (manufactured by Beckman Coulter, Inc.). For the measurement, 0.5 mg to 50 mg of the measurement sample is added to 2 mL of a 5 mass % 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 with the sample suspended in it is dispersed for 1 minute using an ultrasonic disperser, and the particle size of each particle in the range of 2 μm to 60 μm is measured using a Coulter Multisizer II with an aperture of 100 μm in diameter. The number of particles sampled is 50,000. For the measured particle size, a cumulative distribution based on volume is drawn from the smallest diameter side, and the particle size at which the cumulative 50% occurs is called the volume average particle size D 50v It is defined as:

[0088] In this embodiment, the average circularity of the toner particles is not particularly limited, but from the viewpoint of improving the cleaning properties of the toner from the image carrier, it is preferably 0.91 or more and 0.98 or less, more preferably 0.94 or more and 0.98 or less, and even more preferably 0.95 or more and 0.97 or less.

[0089] In this embodiment, the circularity of a toner particle is the perimeter of a circle having the same area as the projected image of the particle divided by the perimeter of the projected image of the particle, and the average circularity of a toner particle is the cumulative circularity of 50% from the smallest side in the distribution of circularity. The average circularity of a toner particle is determined by analyzing at least 3,000 toner particles using a flow-type particle image analyzer.

[0090] The average circularity of the toner particles can be controlled, for example, by adjusting the stirring speed of the dispersion, the temperature of the dispersion, or the retention time in the fusing step.

[0091] The amount of release agent on the toner particle surface can be controlled by, for example, adjusting the amount of release agent charged, the type of release agent, the temperature during melting and kneading, or by performing surface treatment with hot air after pulverization.

[0092] -External additives- The toner produced by the method for producing a toner for developing electrostatic images according to the present embodiment may contain an external additive, if necessary. The toner produced by the method for producing a toner for developing electrostatic images according to this embodiment may be toner particles that do not contain an external additive, or toner particles to which an external additive has been added. Examples of the external additive include inorganic particles. Examples of the inorganic particles include SiO2, TiO2, Al2O3, CuO, ZnO, SnO2, CeO2, Fe2O3, MgO, BaO, CaO, K2O, Na2O, ZrO2, CaO·SiO2, and K2O·(TiO2). n , Al2O3·2SiO2, CaCO3, MgCO3, BaSO4, MgSO4, etc.

[0093] The surface of the inorganic particles as an external additive may be subjected to a hydrophobic treatment. The hydrophobic treatment may be performed, 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 hydrophobizing agent is preferably, for example, 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the inorganic particles.

[0094] 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 fluorine-based polymer particles).

[0095] The amount of the external additive added is, for example, preferably from 0.01% by mass to 10% by mass, and more preferably from 0.01% by mass to 6% by mass, based on the toner particles.

[0096] <Electrostatic image developer> The electrostatic image developer according to this embodiment contains at least the toner produced by the method for producing a toner for developing electrostatic images according to this embodiment. The electrostatic image developer according to the present embodiment may be a one-component developer containing only the toner produced by the method for producing a toner for developing electrostatic images according to the present embodiment, or may be a two-component developer containing the toner and a carrier mixed therewith.

[0097] The carrier is not particularly limited, and may be any known carrier, such as a coated carrier in which the surface of a core material made of magnetic powder is coated with a coating resin, a magnetic powder dispersion type carrier in which magnetic powder is dispersed and mixed in a matrix resin, or a resin impregnated type carrier 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 above carrier are used as a core material and are coated with a coating resin.

[0098] Examples of the magnetic powder include magnetic metals such as iron, nickel, and cobalt, and magnetic oxides such as ferrite and magnetite.

[0099] Examples of the coating resin and matrix resin include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic acid ester copolymer, straight silicone resin containing an organosiloxane bond or a modified product thereof, fluororesin, polyester, polycarbonate, phenolic resin, and epoxy resin. The coating resin and the matrix resin may contain other additives such as conductive particles. Examples of the conductive particles include particles of metals such as gold, silver, and copper, carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

[0100] Here, in order to coat the surface of the core material with a coating resin, a method of coating with a coating layer forming solution in which the coating resin and, if necessary, various additives are dissolved in an appropriate solvent can be mentioned. The solvent is not particularly limited and may be selected taking into consideration the coating resin to be used, the suitability for application, etc. Specific resin coating methods include an immersion method in which the core material is immersed in a solution for forming a coating layer, a spray method in which the solution for forming a coating layer is sprayed onto the surface of the core material, a fluidized bed method in which the solution for forming a coating layer is sprayed onto the core material while it is suspended in flowing air, and a kneader coater method in which the core material of a carrier and the solution for forming a coating layer are mixed in a kneader coater and the solvent is removed.

[0101] In the two-component developer, the mixture ratio (mass ratio) of the toner and the carrier is preferably toner:carrier=1:100 to 30:100, and more preferably 3:100 to 20:100.

[0102] <Image forming device / image forming method> An image forming apparatus / image forming method according to this embodiment will be described. The image forming apparatus according to the present embodiment includes an image carrier, a charging means for charging the surface of the image carrier, an electrostatic image forming means for forming an electrostatic image on the surface of the charged image carrier, a developing means for containing an electrostatic image developer and developing the electrostatic image formed on the surface of the image carrier as a toner image with the electrostatic image developer, a transfer means for transferring the toner image formed on the surface of the image carrier to the surface of a recording medium, and a fixing means for fixing the toner image transferred to the surface of the recording medium. The electrostatic image developer according to the present embodiment is used as the electrostatic image developer.

[0103] In the image forming apparatus according to this embodiment, an image forming method (the image forming method according to this embodiment) is carried out, which includes a charging step of charging the surface of an image carrier, an electrostatic image forming step of forming an electrostatic image on the surface of the charged image carrier, a developing step of developing the electrostatic image formed on the surface of the image carrier as a toner image using the electrostatic image developer according to this embodiment, a transfer step of transferring the toner image formed on the surface of the image carrier to the surface of a recording medium, and a fixing step of fixing the toner image transferred to the surface of the recording medium.

[0104] The image forming apparatus according to the present embodiment may be any of known image forming apparatuses, such as a direct transfer type apparatus in which a toner image formed on the surface of an image holder is directly transferred to a recording medium; an intermediate transfer type apparatus in which a toner image formed on the surface of an image holder is primarily transferred to the surface of an intermediate transfer body, and the toner image transferred to the surface of the intermediate transfer body is then secondarily transferred to the surface of a recording medium; an apparatus equipped with a cleaning means for cleaning the surface of the image holder before charging after the transfer of the toner image; and an apparatus equipped with a discharging means for irradiating the surface of the image holder with discharging light to discharge it before charging after the transfer of the toner image. Among them, an image forming apparatus equipped with a cleaning means for cleaning the surface of the image carrier is preferable, and a cleaning blade is preferable as the cleaning means. In the case of an intermediate transfer type device, the transfer means has, for example, an intermediate transfer body onto whose surface a toner image is transferred, a primary transfer means which primarily transfers the toner image formed on the surface of the image carrier onto the surface of the intermediate transfer body, and a secondary transfer means which secondarily transfers the toner image transferred onto the surface of the intermediate transfer body onto the surface of a recording medium.

[0105] In the image forming apparatus according to the present embodiment, for example, a portion including the developing means may have a cartridge structure (process cartridge) that is detachably attached to the image forming apparatus. As the process cartridge, for example, a process cartridge equipped with the developing means that contains the electrostatic image developer according to the present embodiment is preferably used.

[0106] An example of an image forming apparatus according to the present embodiment will be described below, but the present invention is not limited to this. Note that only the main parts shown in the drawings will be described, and descriptions of the rest will be omitted.

[0107] FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus according to the present embodiment. The image forming apparatus shown in Fig. 1 includes first to fourth electrophotographic image forming units 10Y, 10M, 10C, and 10K (image forming means) that output images of each color of yellow (Y), magenta (M), cyan (C), and black (K) based on color-separated image data. These image forming units (hereinafter sometimes simply referred to as "units") 10Y, 10M, 10C, and 10K are arranged in parallel at predetermined distances from each other in the horizontal direction. These units 10Y, 10M, 10C, and 10K may be process cartridges that are detachable from the image forming apparatus.

[0108] Above each of the units 10Y, 10M, 10C, and 10K in the drawing, an intermediate transfer belt 20 is provided as an intermediate transfer body extending through each unit. The intermediate transfer belt 20 is provided wound around a drive roll 22 and a support roll 24 that are arranged from left to right in the drawing at a distance from each other and contact the inner surface of the intermediate transfer belt 20, and is adapted to run in a direction from the first unit 10Y to the fourth unit 10K. Note that a force is applied to the support roll 24 in a direction away from the drive roll 22 by a spring or the like (not shown), and tension is applied to the intermediate transfer belt 20 wound around them. In addition, an intermediate transfer body cleaning device 30 is provided on the image carrier surface side of the intermediate transfer belt 20, facing the drive roll 22. Further, the developing devices (developing means) 4Y, 4M, 4C, and 4K of the units 10Y, 10M, 10C, and 10K are supplied with toner including four colors of toner, yellow, magenta, cyan, and black, contained in toner cartridges 8Y, 8M, 8C, and 8K, respectively.

[0109] Since the first to fourth units 10Y, 10M, 10C, and 10K have the same configuration, the first unit 10Y that forms a yellow image and is disposed upstream in the direction in which the intermediate transfer belt travels will be described here as a representative example. Note that by assigning reference numerals of magenta (M), cyan (C), and black (K) instead of yellow (Y) to parts equivalent to those of the first unit 10Y, descriptions of the second to fourth units 10M, 10C, and 10K will be omitted.

[0110] The first unit 10Y has a photoconductor 1Y that acts as an image carrier. Around the photoconductor 1Y, a charging roll (an example of a charging means) 2Y that charges the surface of the photoconductor 1Y to a predetermined potential, an exposure device (an example of an electrostatic image forming means) 3 that exposes the charged surface to a laser beam 3Y based on a color-separated image signal to form an electrostatic image, a developing device (an example of a developing means) 4Y that supplies charged toner to the electrostatic image to develop it, a primary transfer roll (an example of a primary transfer means) 5Y that transfers the developed toner image onto an intermediate transfer belt 20, and a photoconductor cleaning device (an example of a cleaning means) 6Y that removes toner remaining on the surface of the photoconductor 1Y after the primary transfer are arranged in this order. The primary transfer roll 5Y is disposed inside the intermediate transfer belt 20 and is provided at a position facing the photoconductor 1Y. Furthermore, a bias power supply (not shown) that applies a primary transfer bias is connected to each of the primary transfer rolls 5Y, 5M, 5C, and 5K. Each bias power supply varies the transfer bias applied to each primary transfer roll under the control of a control unit (not shown).

[0111] Hereinafter, an operation of forming a yellow image in first unit 10Y will be described. First, prior to operation, the surface of the photoconductor 1Y is charged to a potential of −600V to −800V by the charging roll 2Y. The photoconductor 1Y has a conductivity (for example, a volume resistivity at 20° C. of 1×10 -6The photosensitive layer is formed by laminating a photosensitive layer on a substrate having a resistivity of Ωcm or less. This photosensitive layer is usually highly resistive (the resistance of ordinary resins), but when irradiated with a laser beam 3Y, the resistivity of the portion irradiated with the laser beam changes. A laser beam 3Y is output to the charged surface of the photoreceptor 1Y via an exposure device 3 in accordance with image data for yellow sent from a control unit (not shown). The laser beam 3Y is irradiated onto the photosensitive layer on the surface of the photoreceptor 1Y, and an electrostatic charge image of a yellow image pattern is formed on the surface of the photoreceptor 1Y.

[0112] An electrostatic image is an image formed on the surface of the photoconductor 1Y by electrostatic charging. The laser beam 3Y reduces the resistivity of the irradiated parts of the photosensitive layer, causing the charged charges on the surface of the photoconductor 1Y to flow, while the charges remain in the parts not irradiated by the laser beam 3Y. This is a so-called negative latent image. The electrostatic image formed on the photoconductor 1Y is rotated to a predetermined developing position as the photoconductor 1Y travels. Then, at this developing position, the electrostatic image on the photoconductor 1Y is made visible as a toner image (developed image) by the developing device 4Y.

[0113] The developing device 4Y contains an electrostatic image developer including at least yellow toner and a carrier, for example. The yellow toner is triboelectrically charged by being stirred inside the developing device 4Y, and is held on a developer roll (an example of a developer holder) with a charge of the same polarity (negative polarity) as the charge on the photoconductor 1Y. As the surface of the photoconductor 1Y passes through the developing device 4Y, the yellow toner electrostatically adheres to the discharged latent image portion on the surface of the photoconductor 1Y, and the latent image is developed with the yellow toner. The photoconductor 1Y on which the yellow toner image has been formed continues to travel at a predetermined speed, and the toner image developed on the photoconductor 1Y is transported to a predetermined primary transfer position.

[0114] When the yellow toner image on the photoconductor 1Y is transported to the primary transfer position, a primary transfer bias is applied to the primary transfer roll 5Y, and an electrostatic force from the photoconductor 1Y toward the primary transfer roll 5Y acts on the toner image, and the toner image on the photoconductor 1Y is transferred onto the intermediate transfer belt 20. The transfer bias applied at this time has a polarity (+) opposite to the polarity (-) of the toner, and in the first unit 10Y, for example, it is controlled to +10 μA by a control unit (not shown). On the other hand, the toner remaining on the photoconductor 1Y is removed and collected by the photoconductor cleaning device 6Y.

[0115] Further, the primary transfer bias applied to the primary transfer rolls 5M, 5C, and 5K subsequent to the second unit 10M is also controlled in accordance with the first unit. In this manner, the intermediate transfer belt 20 onto which the yellow toner image has been transferred by the first unit 10Y is conveyed successively through the second to fourth units 10M, 10C, and 10K, where the toner images of the respective colors are transferred in a superimposed manner.

[0116] The intermediate transfer belt 20 onto which the four color toner images have been transferred in multiple layers through the first to fourth units reaches a secondary transfer section that is composed of the intermediate transfer belt 20, a support roll 24 that contacts the inner surface of the intermediate transfer belt, and a secondary transfer roll (an example of a secondary transfer means) 26 arranged on the image bearing surface side of the intermediate transfer belt 20. Meanwhile, a recording paper (an example of a recording medium) P is fed at a predetermined timing into the gap between the secondary transfer roll 26 and the intermediate transfer belt 20 via a supply mechanism, and a secondary transfer bias is applied to the support roll 24. The transfer bias applied at this time has a (-) polarity that is the same as the (-) polarity of the toner, and an electrostatic force from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, so that the toner image on the intermediate transfer belt 20 is transferred onto the recording paper P. The secondary transfer bias at this time is determined according to the resistance detected by a resistance detection means (not shown) that detects the resistance of the secondary transfer section, and is voltage-controlled.

[0117] Thereafter, the recording paper P is sent to a pressure contact portion (nip portion) of a pair of fixing rolls in a fixing device (one example of a fixing means) 28, where the toner image is fixed onto the recording paper P, forming a fixed image.

[0118] The recording paper P onto which the toner image is transferred can be, for example, plain paper used in electrophotographic copying machines, printers, etc. In addition to the recording paper P, other examples of the recording medium include overhead projector sheets, etc. To further improve the smoothness of the image surface after fixing, it is preferable that the surface of the recording paper P is also smooth. For example, coated paper in which the surface of ordinary paper is coated with resin or the like, art paper for printing, etc. are preferably used.

[0119] After the color image has been fixed, the recording paper P is conveyed toward the discharge section, and the series of color image forming operations is completed.

[0120] <Process cartridge / toner cartridge> The process cartridge according to this embodiment will be described. The process cartridge according to this embodiment is a process cartridge that contains the electrostatic image developer according to this embodiment, is equipped with a developing means that develops an electrostatic image formed on the surface of an image carrier using the electrostatic image developer into a toner image, and is detachably attached to an image forming apparatus.

[0121] In addition, the process cartridge according to this embodiment is not limited to the above configuration, and may be configured to include a developing device and, as necessary, at least one other means selected from an image carrier, a charging means, an electrostatic image forming means, and a transfer means.

[0122] An example of a process cartridge according to the present embodiment will be described below, but the present invention is not limited to this example. Note that only the main parts shown in the drawings will be described, and descriptions of the rest will be omitted.

[0123] FIG. 2 is a schematic diagram showing the process cartridge according to the present embodiment. The process cartridge 200 shown in FIG. 2 is configured by, for example, a housing 117 having a mounting rail 116 and an opening 118 for exposure, and integrally combining and holding a photoconductor 107 (an example of an image carrier), a charging roll 108 (an example of a charging means) provided around the photoconductor 107, a developing device 111 (an example of a developing means), and a photoconductor cleaning device 113 (an example of a cleaning means), which are assembled into a cartridge. In FIG. 2, 109 denotes an exposure device (an example of an electrostatic image forming means), 112 denotes a transfer device (an example of a transfer means), 115 denotes a fixing device (an example of a fixing means), and 300 denotes recording paper (an example of a recording medium).

[0124] Next, the toner cartridge according to this embodiment will be described. The toner cartridge according to the present embodiment is a toner cartridge that contains the toner according to the present embodiment and is detachably attached to an image forming apparatus. The toner cartridge contains replenishment toner to be supplied to a developing unit provided in the image forming apparatus.

[0125] 1 is an image forming apparatus having a configuration in which toner cartridges 8Y, 8M, 8C, and 8K can be attached and detached, and the developing devices 4Y, 4M, 4C, and 4K are connected to the toner cartridges corresponding to the respective developing devices (colors) through toner supply pipes (not shown). When the toner contained in the toner cartridge becomes low, the toner cartridge is replaced. EXAMPLES

[0126] Hereinafter, the present embodiment will be described in more detail with reference to examples and comparative examples, but the present embodiment is not limited to these examples. Note that "parts" and "%" indicating amounts are based on mass unless otherwise specified.

[0127] Example 1 -Preparation of amorphous polyester resin (A)- Dimethyl adipate: 74 parts Dimethyl terephthalate: 192 parts Bisphenol A ethylene oxide adduct: 216 parts Ethylene glycol: 38 parts Tetrabutoxytitanate (catalyst): 0.037 parts, The above components were placed in a heated and dried two-necked flask, nitrogen gas was introduced into the vessel to maintain an inert atmosphere, and the temperature was raised while stirring, after which a polycondensation reaction was carried out at 160°C for 7 hours, after which the pressure was gradually reduced to 10 Torr while the temperature was raised to 220°C and maintained for 4 hours. The pressure was once returned to normal, 9 parts of trimellitic anhydride was added, the pressure was gradually reduced again to 10 Torr, and the mixture was maintained for 1 hour to synthesize polyester resin (A). The glass transition temperature of the obtained polyester resin (A) was measured by a differential scanning calorimeter (DSC) according to the above-mentioned measurement method, and was found to be 65° C. The molecular weight of the obtained polyester resin (A) was measured by GPC according to the above-mentioned measurement method, and was found to be 12,000 in weight average molecular weight.

[0128] -Preparation of amorphous polyester resin particle dispersion (A)- Polyester resin (A): 160 parts Ethyl acetate: 233 parts Sodium hydroxide solution (0.3 mol / L): 0.1 part The above components were placed in a separable flask, heated to 70°C, and stirred with a Three-One Motor (manufactured by Shinto Scientific Co., Ltd.) to prepare a resin mixture. While further stirring this resin mixture, 500 parts of ion-exchanged water was gradually added, phase-inversion emulsification was performed, and the solvent was removed to obtain an amorphous polyester resin particle dispersion (A) (solid content concentration: 20%). The volume average particle size of the resin particles in the dispersion was 160 nm.

[0129] -Preparation of amorphous polyester resin (B)- Bisphenol A ethylene oxide 2 mole adduct: 114 parts Bisphenol A propylene oxide 2 mole adduct: 84 parts Dimethyl terephthalate: 75 parts Dodecenyl succinic acid: 19.5 parts Trimellitic acid: 7.5 parts The above components were placed in a volumetric flask equipped with a stirrer, nitrogen inlet tube, temperature sensor, and distillation column, and the temperature was raised to 190°C over 1 hour. After stirring the reaction system, 3.0 parts of dibutyltin oxide were added. The temperature was then raised from 190°C to 240°C over 6 hours while distilling off the water produced, and the dehydration condensation reaction was continued at 240°C for another 2 hours to synthesize polyester resin (B). The glass transition temperature of the resulting polyester resin (B) was 57°C and the weight average molecular weight was 58,000.

[0130] -Preparation of amorphous polyester resin particle dispersion (B)- Polyester resin (B): 160 parts Ethyl acetate: 233 parts Sodium hydroxide solution (0.3 mol / L): 0.1 part The above components were placed in a separable flask, heated to 70°C, and stirred with a Three-One Motor (manufactured by Shinto Scientific Co., Ltd.) to prepare a resin mixture. While further stirring this resin mixture, 500 parts of ion-exchanged water was gradually added, phase-inversion emulsification was performed, and the solvent was removed to obtain an amorphous polyester resin particle dispersion (B) (solid content concentration: 20%). The volume average particle size of the resin particles in the dispersion was 160 nm.

[0131] -Preparation of crystalline polyester resin (C)- Dimethyl sebacate: 98 parts Sodium dimethyl isophthalate-5-sulfonate: 20 parts 1,5-Pentanediol: 100 parts Dibutyltin oxide (catalyst): 0.3 parts The above components were placed in a separable flask, and the air in the container was turned into an inert atmosphere with nitrogen gas by reducing the pressure, and the mixture was stirred and refluxed at 180°C for 5 hours using a Three-One Motor (manufactured by Shinto Scientific Co., Ltd.). The temperature was then gradually increased to 230°C under reduced pressure and the mixture was stirred for 2 hours. When the mixture became viscous, it was air-cooled to stop the reaction, and a crystalline polyester resin (C) was obtained. The weight average molecular weight (Mw) of the obtained crystalline polyester resin (C) was 9,700.

[0132] -Preparation of crystalline polyester resin particle dispersion (C)- Crystalline polyester resin (C): 90 parts Anionic surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Neogen RK): 1.8 parts Ion-exchanged water: 210 parts The above components were mixed and heated to 100°C, dispersed using a homogenizer (IKA Ultra Turrax T50), and then dispersed for 1 hour using a pressure discharge type Gaulin homogenizer to prepare a crystalline polyester resin particle dispersion (C) (solids concentration: 20%) with a volume average particle size of 200 nm.

[0133] -Preparation of release agent particle dispersion (W)- Paraffin wax (Nippon Seiro Co., Ltd., FNP0090): 100 parts Anionic surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Neogen RK): 1.0 part - Ion-exchanged water: 400 parts The above components were mixed and heated to 95°C, and dispersed using a homogenizer (Ultra Turrax T50, manufactured by IKA Corporation). Dispersion processing was carried out for 3 hours using a pressure discharge type Gaulin homogenizer, to prepare a release agent particle dispersion (W) (solid content: 20%) having a volume average particle size of 240 nm.

[0134] -Preparation of colorant particle dispersion (K)- Carbon black (Cabot, Regal 330): 50 parts Ionic surfactant Neogen RK (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 5 parts Ion-exchanged water: 192.9 parts The above components were mixed and treated for 10 minutes at 240 MPa with an Ultimizer (manufactured by Sugino Machine Ltd.) to prepare a colorant particle dispersion (K) (solids concentration: 20% by mass).

[0135] <Step of forming aggregated particles> Ion-exchanged water: 5,000 parts Amorphous polyester resin particle dispersion (A): 2000 parts Amorphous polyester resin particle dispersion (B): 2000 parts Crystalline polyester resin particle dispersion (C): 4,000 parts Release agent particle dispersion (W): 1,500 parts Colorant particle dispersion (K): 1,500 parts The above materials were placed in a circulation reaction vessel equipped with a stirring blade having four paddle blades, and 0.1 N (=0.1 mol / L) nitric acid was added to adjust the pH to 3.8. An aqueous aluminum sulfate solution was prepared by dissolving 15 parts of aluminum sulfate in 1000 parts of ion-exchanged water. While the contents were circulated in the circulation reaction tank for stirring and dispersion, the aqueous aluminum sulfate solution was added from the inlet. Next, the contents were circulated for 10 minutes while maintaining the temperature at 30°C, and stirred and dispersed. Next, the disperser was stopped, the bottom valve at the bottom of the stirring vessel was closed, and 3,000 parts of ion-exchanged water was charged from the inlet, and then charged into the stirring vessel via the disperser and conduit, and mixed with the dispersion by stirring. Next, the contents were heated to 45° C. in the jacket while continuing to stir, and maintained at that temperature until the volume average particle size of the aggregated particles reached 4.0 μm.

[0136] <Second flocculation step> A mixture of 2000 parts of the amorphous polyester resin particle dispersion (A) and 2000 parts of the amorphous polyester resin particle dispersion (B) was charged into a stirring tank and held for 30 minutes to obtain a dispersion containing second aggregated particles.

[0137] <Agglomeration stop process> 200 parts of EDTA (ethylenediaminetetraacetic acid) was added to the dispersion liquid containing the second aggregated particles, and then a 1N (=1 mol / L) aqueous solution of sodium hydroxide was added to adjust the pH to 9, and the mixture was maintained for 5 minutes.

[0138] <Fusing process> While continuing stirring in the mixing vessel, the temperature was raised to 85°C at a rate of 0.5°C / min, and then the mixing Reynolds number was increased to 1.0×10 5 The stirring was set so that the pH was 7.6. Then, 100 parts of an acidic aqueous solution was added, and the pH was maintained at 7.6 for 3 hours. After that, the mixture was cooled to 30°C at 5°C / min (first cooling). Then, the mixture was heated to 55°C at a heating rate of 0.2°C / min (reheating), maintained for 30 minutes, and then cooled to 30°C at 0.5°C / min (second cooling).

[0139] <Cleaning and drying processes> Next, the solid content was filtered off, washed with ion-exchanged water, and dried to obtain toner particles (1) having a volume average particle size of 5.2 μm.

[0140] <External addition of additives> 100 parts of the obtained toner particles (1) and 1.5 parts of hydrophobic silica (RY50, manufactured by Nippon Aerosil Co., Ltd.) were mixed and mixed for 30 seconds at a rotation speed of 10,000 rpm using a sample mill. The mixture was sieved using a vibrating sieve with an opening of 45 μm to obtain toner (1) (toner for developing electrostatic images). The volume average particle diameter of toner (1) was 5.0 μm.

[0141] <Preparation of carrier> After 500 parts of spherical magnetite powder particles (volume average particle diameter 0.55 μm) were stirred with a Henschel mixer, 5 parts of a titanate-based coupling agent were added, and the mixture was heated to 100 ° C and stirred for 30 minutes. Next, 6.25 parts of phenol, 9.25 parts of 35% formalin, 500 parts of magnetite particles treated with a titanate-based coupling agent, 6.25 parts of 25% ammonia water, and 425 parts of water were added to a four-neck flask and stirred, and reacted at 85 ° C for 120 minutes while stirring. Next, the mixture was cooled to 25 ° C, 500 parts of water were added, and the supernatant liquid was removed and the precipitate was washed with water. The washed precipitate was heated and dried under reduced pressure to obtain a carrier (CA) with an average particle size of 35 μm.

[0142] <Mixing toner and carrier> The toner (1) and the carrier (CA) were placed in a V blender in a ratio of toner (1):carrier (CA) = 5:95 (mass ratio) and stirred for 20 minutes to obtain a developer (1) (electrostatic image developer).

[0143] Example 2 In the fusion process, the stirring Reynolds number is 1.0×10 6 Toner particles were prepared in the same manner as in Example 1, except that the stirring was changed so that the toner particles were mixed at a rate of 1000g / ml.

[0144] Example 3 In the fusion process, the stirring Reynolds number is 9.0×10 5 Toner particles were prepared in the same manner as in Example 1, except that the stirring was changed so that the toner particles were mixed at a rate of 1000g / ml.

[0145] Example 4 In the fusion process, the stirring Reynolds number is 6.0×10 4 Toner particles were prepared in the same manner as in Example 1, except that the stirring was changed so that the toner particles were mixed at a rate of 1000g / ml.

[0146] Example 5 In the fusion process, the stirring Reynolds number is 5.5 x 10 4 Toner particles were prepared in the same manner as in Example 1, except that the stirring was changed so that the toner particles were mixed at a rate of 1000g / ml.

[0147] Example 6 In the fusion process, the stirring Reynolds number is 5.0×10 4 Toner particles were prepared in the same manner as in Example 1, except that the stirring was changed so that the toner particles were mixed at a rate of 1000g / ml.

[0148] Example 7 Toner particles were prepared in the same manner as in Example 1, except that in the step of forming aggregated particles, the amount of the crystalline polyester resin particle dispersion liquid (C) was changed to 8,000 parts.

[0149] Example 8 Toner particles were prepared in the same manner as in Example 1, except that in the step of forming aggregated particles, the amount of the crystalline polyester resin particle dispersion liquid (C) was changed to 1500 parts.

[0150] Example 9 In the step of forming aggregated particles, the amount of crystalline polyester resin particle dispersion (C) was changed to 5340 parts. In the step of fusing, the temperature to be raised the first time was changed to 84° C. Except for the above, the toner particles were prepared in the same manner as in Example 1.

[0151] Example 10 In the step of forming aggregated particles, the amount of crystalline polyester resin particle dispersion (C) was changed to 2000 parts. In the step of fusing, the temperature to be raised the first time was changed to 87° C. Other than that, toner particles were produced in the same manner as in Example 1.

[0152] Example 11 Toner particles were prepared in the same manner as in Example 1, except that in the fusion step, the temperature to which the temperature was raised the first time was changed to 75°C.

[0153] Example 12 Toner particles were prepared in the same manner as in Example 1, except that in the fusion step, the temperature to which the temperature was raised the first time was changed to 78°C.

[0154] Example 13 Toner particles were prepared in the same manner as in Example 1, except that in the fusion step, the temperature to which the temperature was raised the first time was changed to 88°C.

[0155] Example 14 Toner particles were prepared in the same manner as in Example 1, except that in the fusion step, the temperature to which the temperature was raised the first time was changed to 92°C.

[0156] Example 15 Toner particles were prepared in the same manner as in Example 1, except that in the fusion step, the temperature to which the temperature was raised the first time was changed to 95°C.

[0157] (Example 16) Toner particles were produced in the same manner as in Example 1, except that in the step of forming aggregated particles, the stirring blades installed in the circulation reaction vessel were changed to four-blade propeller blades.

[0158] Comparative Example 1 In the fusion process, the stirring Reynolds number is 1.0×10 7 Toner particles were prepared in the same manner as in Example 1, except that the stirring was changed so that the toner particles were mixed at a rate of 1000g / ml.

[0159] Comparative Example 2 In the fusion process, the stirring Reynolds number is 3.0×10 4 Toner particles were prepared in the same manner as in Example 1, except that the stirring was changed so that the toner particles were mixed at a rate of 1000g / ml.

[0160] <Method of measuring binder resin viscosity using a flow tester> The viscosity of the binder resin was measured using a high-performance flow tester CFT-500 (manufactured by Shimadzu Corporation) with a die hole diameter of 1.0 mm and a pressure load of 10 kgf / cm. 2 Under the conditions of a heating rate of 7°C / min and a starting temperature of 60°C, 3 The viscosity (melt viscosity) of the sample is determined when it is melted and poured out.

[0161] <Image unevenness on moist paper under high temperature and humidity conditions (image unevenness suppression)> Each developer was placed in the developing device of a modified image forming apparatus ApeosPortIV C5575 (manufactured by Fujifilm Business Innovation Co., Ltd.). Using embossed paper (manufactured by Tokushu Tokai Paper Co., Ltd., Rezac 66, 203 gsm) that had been left for one day in an environment of 28°C and 85% RH to condition the humidity, 10,000 rectangular patch images were printed so that the image density was 20%. Nine points of the 10,000th image were measured for color reproducibility (L) using a spectrometer (938 Spectrodentitometer, X-Rite Co., Ltd.). * , a * , b * ) was carried out at a total of nine L * Value, a * value and b * The average value of the values ​​was calculated, and the color difference ΔE was calculated using the following formula. ΔE = {(L * -L * Average value) 2 +(a * -a * Average value) 2 +(b * -b * Average value) 2} 0.5 The largest value among these nine points is ΔE max The evaluation was performed using the following grades. The evaluation result is preferably G1 to G3. G1:ΔE max is 0 or more and less than 0.5 G2:ΔE max is 0.5 or more and less than 2 G3:ΔE max is 2 or more and less than 3.5 G4:ΔE max is 3.5 or more and less than 5 G5:ΔE max 5 or more

[0162] <Method of measuring fixing temperature (low temperature fixing ability)> Using the same machine and environmental conditions as those used in the evaluation of image unevenness on moist paper, and using the same paper, one solid black image was printed with a set temperature of 160° C. Wait until the entire fixing unit had cooled to room temperature, then increase the set temperature from 160° C. to 210° C. in increments of 5° C. The image surface of each of the obtained fixed images was folded under a load of 3 kgf, and the degree of peeling of the image at the fold was observed, and the width of the paper that appeared at the fold as a result of the image peeling was measured. The fixing temperature at which the width became 0.5 mm or less was taken as MFT (minimum fixing temperature, ° C.). The lower the minimum fixing temperature, the better the low-temperature fixability, and the evaluation was performed using the following grades. The evaluation result is preferably G1 to G3. G1: MFT is 170℃ or less G2: MFT is 175℃ or higher and 180℃ or lower G3: MFT is 185℃ or higher and 190℃ or lower G4: MFT is between 195℃ and 200℃ G5: MFT is 205℃ or higher [Table 1]

[0163] The ratio of the crystalline polyester resin in Table 1 is the ratio of the crystalline polyester resin in the binder resin in the obtained toner particles, and the viscosity of the binder resin is the viscosity of the binder resin of the binder resin particles contained in the aggregated particles at the start of the fusion step, at a temperature after the temperature is increased in the fusion step.

[0164] From the above results, it is understood that the present embodiment provides a toner for developing electrostatic images which is superior in suppressing image unevenness as compared with the comparative example.

[0165] (((1))) A method for producing a dispersion liquid comprising the steps of aggregating particles including binder resin particles in the dispersion liquid to form aggregated particles, and heating and fusing the aggregated particles, the method comprising the steps of: (a) agitating the dispersion liquid during the fusing step; and (b) having a stirring Reynolds number of 5.0×10 4 Above 1.0×10 6 A method for producing a toner for developing an electrostatic image, comprising: (((2))) The method for producing a toner for developing electrostatic images according to (((1))), wherein in the fusing step, η is a viscosity of the binder resin of the binder resin particles, and T is a temperature after the heating step, 1,000 Pa s≦η(T)≦4,500 Pa s is satisfied. (((3))) The method for producing a toner for developing electrostatic images according to (((2))), wherein, in the fusing step, η is a viscosity of the binder resin of the binder resin particles, and T is a temperature after the heating step, 2,000 Pa s≦η(T)≦4,500 Pa s is satisfied. (((4))) The method for producing a toner for developing electrostatic images according to any one of (((1))) to (((3))), wherein the proportion of the crystalline polyester resin contained in the binder resin in the obtained toner particles is 15% by mass or more and 50% by mass or less. (((5))) The method for producing a toner for developing electrostatic images according to (((4))), wherein the proportion of the crystalline polyester resin contained in the binder resin in the obtained toner particles is from 20% by mass to 40% by mass. (((6))) The method for producing a toner for developing electrostatic images according to any one of (((1))) to (((5))), wherein the solid content of the dispersion in the fusing step is 8% by mass or more and 30% by mass or less. (((7))) The method for producing a toner for developing electrostatic images according to any one of (((1))) to (((6))), wherein the temperature after the heating in the fusing step is equal to or higher than the glass transition temperature of the binder resin (glass transition temperature of the binder resin + 40°C) inclusive. (((8))) The stirring Reynolds number is 6.0 × 10 4 Above 9.0×10 5 The method for producing a toner for developing electrostatic images according to any one of the following ((1)) to ((7)). (((9))) The method for producing a toner for developing an electrostatic image according to any one of (((1))) to (((8))), wherein an acidic aqueous solution is added in the fusing step. (((10))) The method for producing a toner for developing electrostatic images according to any one of (((1))) to (((9))), wherein the pH in the fusing step is 7 or more and 10 or less. (((11))) The method for producing a toner for developing electrostatic images according to any one of (((1))) to (((10))), wherein a stirring device equipped with a propeller-type, anchor-type or paddle-type stirring blade and a rotating shaft is used to stir the dispersion during the fusing step.

[0166] According to the invention of (((1))), (((9))) or (((11))), the present invention includes a step of aggregating particles including binder resin particles in a dispersion liquid to form aggregated particles, and a step of heating and raising the temperature of the aggregated particles to fuse them together, and the stirring Reynolds number in stirring the dispersion liquid during the fusing step is 5.0×10 4 Less than or 1.0 x 10 6 The present invention provides a method for producing a toner for developing electrostatic images, which is excellent in suppressing image unevenness compared to the case where the toner is more than 100%. According to the invention related to (((2))), there is provided a method for producing a toner for developing electrostatic images, which is superior in suppressing image unevenness compared to when η(T) is less than 1,000 Pa·s or exceeds 4,500 Pa·s. According to the invention related to (((3))), a method for producing a toner for developing electrostatic images is provided which is superior in suppressing image unevenness compared to when η(T) is less than 2,000 Pa·s or exceeds 4,500 Pa·s. According to the invention related to (((4))), there is provided a method for producing a toner for developing electrostatic images, which has excellent low-temperature fixing properties and suppresses image unevenness, compared to cases in which the proportion of the crystalline polyester resin contained in the binder resin in the obtained toner particles is less than 15% by mass or more than 50% by mass. According to the invention related to (((5))), there is provided a method for producing a toner for developing electrostatic images, which has excellent low-temperature fixing properties and suppresses image unevenness, compared to cases in which the proportion of the crystalline polyester resin contained in the binder resin in the obtained toner particles is less than 20% by mass or more than 40% by mass. According to the invention related to (((6))), there is provided a method for producing a toner for developing electrostatic images, which is superior in suppressing image unevenness compared to when the solid content of the dispersion in the fusing step is less than 8 mass % or exceeds 30 mass %. According to the invention related to (((7))), there is provided a method for producing a toner for developing electrostatic images, which is superior in suppressing image unevenness compared to a case in which the temperature of the dispersion liquid in the fusion step is lower than the glass transition temperature of the binder resin or higher than (the glass transition temperature of the binder resin + 40° C.). According to the invention related to (((8))), the stirring Reynolds number is 6.0×10 4 Less than or equal to 9.0 x 10 5 The present invention provides a method for producing a toner for developing electrostatic images, which is more excellent in suppressing image unevenness than when the toner is more than 100%. According to the invention related to (((10))), a method for producing a toner for developing electrostatic images is provided which is superior in suppressing image unevenness compared to a case where the pH in the fusing step is less than 6 or more than 10. [Explanation of symbols]

[0167] 1Y, 1M, 1C, 1K Photoconductor (an example of an image carrier) 2Y, 2M, 2C, 2K Charging roll (an example of a charging means) 3 Exposure device (an example of an electrostatic image forming means) 3Y, 3M, 3C, 3K laser beam 4Y, 4M, 4C, 4K developing device (an example of developing means) 5Y, 5M, 5C, 5K Primary transfer roll (an example of a primary transfer means) 6Y, 6M, 6C, 6K Photoconductor cleaning device (an example of a cleaning means) 8Y, 8M, 8C, 8K toner cartridges 10Y, 10M, 10C, 10K Image forming units 20 Intermediate transfer belt (an example of an intermediate transfer body) 22 Driving Roll 24 Support roll 26 Secondary transfer roll (an example of a secondary transfer means) 30 Intermediate transfer body cleaning device 107 Photoconductor (an example of an image carrier) 108 Charging roll (an example of charging means) 109 Exposure device (an example of electrostatic image forming means) 111 Developing device (an example of developing means) 112 Transfer device (an example of a transfer means) 113 Photoconductor cleaning device (an example of a cleaning means) 115 Fixing device (an example of fixing means) 116 Mounting Rail 118 Exposure Aperture 117 Cabinet 200 Process Cartridge 300 Recording paper (an example of a recording medium) P Recording paper (an example of a recording medium)

Claims

1. a step of aggregating particles including binder resin particles in the dispersion to form aggregated particles; and heating the aggregated particles to elevate the temperature to fuse them together. The stirring Reynolds number in stirring the dispersion during the fusion step is 5.0×10 ４ Above 1.0 x 10 ６ is less than or equal to A method for producing a toner for developing electrostatic images.

2. 2. The method for producing a toner for developing an electrostatic image according to claim 1, wherein, in the fusing step, a viscosity of the binder resin of the binder resin particles is η, and a temperature after the heating step is T, the viscosity satisfies 1,000 Pa·s≦η(T)≦4,500 Pa·s.

3. 3. The method for producing a toner for developing an electrostatic image according to claim 2, wherein, in the fusing step, a viscosity of the binder resin of the binder resin particles is η, and a temperature after the heating step is T, the viscosity satisfies 2,000 Pa·s≦η(T)≦4,500 Pa·s.

4. 2. The method for producing a toner for developing electrostatic images according to claim 1, wherein the ratio of the crystalline polyester resin contained in the binder resin in the obtained toner particles is from 15% by mass to 50% by mass.

5. 5. The method for producing a toner for developing electrostatic images according to claim 4, wherein the ratio of the crystalline polyester resin contained in the binder resin in the obtained toner particles is from 20% by mass to 40% by mass.

6. 2. The method for producing a toner for developing an electrostatic image according to claim 1, wherein the solid content of the dispersion in the fusing step is from 8% by mass to 30% by mass.

7. 2. The method for producing a toner for developing an electrostatic image according to claim 1, wherein the temperature after the heating in the fusing step is equal to or higher than the glass transition temperature of the binder resin (glass transition temperature of the binder resin + 40° C.).

8. The stirring Reynolds number is 6.0×10 ４ Above 9.0 x 10 ５ 2. The method for producing a toner for developing electrostatic images according to claim 1, wherein the toner is:

9. 2. The method for producing a toner for developing an electrostatic image according to claim 1, wherein an acidic aqueous solution is added in the fusing step.

10. 2. The method for producing a toner for developing an electrostatic image according to claim 1, wherein the pH in the fusing step is 6 or more and 10 or less.

11. 2. The method for producing a toner for developing an electrostatic image according to claim 1, wherein a stirring device equipped with a propeller-type, anchor-type or paddle-type stirring blade and a rotating shaft is used to stir the dispersion during the fusing step.

Images