Method for producing electrostatic latent image developing toner

Abstract

A method for producing an electrostatic latent image developing toner includes: a step of aggregating particles containing binder resin particles in a dispersion liquid to form aggregated particles; and a step for heating and raising the temperature of the aggregated particles and welding the aggregated particles. The stirring Reynolds number when the dispersion liquid is stirred during the welding step is from 5.0 * 104 to 1.0 * 106 (inclusive).

Description

Technical Field

[0001] The present invention relates to a method for producing a toner for developing electrostatic latent images. Background Art

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

[0003] For example, Patent Document 1 discloses a method for producing a colorant for electrostatic latent image development, which comprises: a coagulant mixing step, in which a dispersion containing binding resin particles is circulated between a stirring tank and a disperser for imparting mechanical shear force, a coagulant is added to the dispersion containing the binding resin particles, and the coagulant is mixed in the dispersion containing the binding resin particles; an agglomeration step, in which, after reducing the viscosity of the dispersion that has passed the coagulant mixing step, the dispersion is heated to form agglomerated particles; and a merging step, in which the dispersion containing the agglomerated particles is heated to melt and merge the agglomerated particles to form colorant particles.

[0004] Patent Document 2 discloses a method for producing toner particles, characterized in that the method includes a granulation step of dispersing a raw material for toner in an aqueous medium using a stirring member, wherein the stirring member uses a stirring device having at least a rotating shaft and stirring blades, and the angles α (°) formed by adjacent stirring blades on a plane perpendicular to the rotating shaft with the rotating shaft as the center are respectively

[0005] 100≤α≤140

[0006] , and the diameter d (m) of the stirring blade is equal to the inner diameter D (m) of the granulation container in which the granulation process is performed.

[0007] 0.05≤d / D≤0.35, and

[0008] When the peripheral speed of the stirring blade is set to A (m / s),

[0009] 20≤A≤40

[0010] relationship.

[0011] Furthermore, Patent Document 3 discloses a stirring shearing speed of 10 s-1 The viscosity is 1 Pa·s or more and the thixotropic index is given by the following formula: (shear rate 1s -1 Viscosity at 10 s) / (shear rate 10 s -1 Viscosity at 40 °C

[0012] A method for producing a toner by an emulsion aggregation method using an agglomeration liquid having a thixotropic index of 7 or more, the method comprising an aggregation step in which the agglomeration is performed by stirring with a multi-axis stirring blade at a shear rate of 10 s -1 The following parts are 50% by volume or less and 400s -1 The stirring blade was rotated so that the shear rate portion above the above was 1 volume % or less.

[0013] Patent Document 1: Japanese Patent Application Publication No. 2022-145174

[0014] Patent Document 2: Japanese Patent Application Publication No. 2008-268313

[0015] Patent Document 3: Japanese Patent Application Publication No. 2019-8042 Summary of the invention

[0016] The present invention provides a method for producing a toner for electrostatic latent image development, comprising the steps of: aggregating particles containing binder resin particles in a dispersion to form aggregated particles; and heating the aggregated particles to fuse them, wherein the dispersion is stirred at a stirring Reynolds number of less than 5.0×10 4 or more than 1.0×10 6 Compared with the case of , the image unevenness suppression is excellent.

[0017] Means for solving the above-mentioned problems include the following.

[0018] <1> A method for producing a toner for electrostatic latent image development, comprising the steps of: aggregating particles containing binder resin particles in a dispersion to form aggregated particles; and heating the aggregated particles to fuse them, wherein the dispersion is stirred at a stirring Reynolds number of 5.0×10 4 Above and 1.0×10 6 the following.

[0019] <2> The method for producing a toner for electrostatic latent image development according to <1>, wherein, in the welding step, when the viscosity of the binder resin of the binder resin particles is set to η and the temperature after the heating is set to T, 1,000 Pa·s≤η(T)≤4,500 Pa·s is satisfied.

[0020] <3> The method for producing a toner for electrostatic latent image development according to <2>, wherein, in the welding step, when the viscosity of the binder resin of the binder resin particles is set to η and the temperature after the heating is set to T, 2,000 Pa·s≤η(T)≤4,500 Pa·s is satisfied.

[0021] <4> The method for producing an electrostatic latent image developing toner according to any one of <1> to <3>, wherein a 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.

[0022] <5> The method for producing a toner for developing an electrostatic latent image according to <4>, wherein a 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.

[0023] <6> The method for producing a toner for developing an electrostatic latent image according to any one of <1> to <5>, wherein a solid content of the dispersion in the welding step is 8% by mass or more and 30% by mass or less.

[0024] <7> The method for producing a toner for electrostatic latent image development according to any one of <1> to <6>, wherein the temperature after the temperature increase in the welding step is greater than the glass transition temperature of the binder resin and less than (glass transition temperature of the binder resin + 40°C).

[0025] <8> The method for producing a toner for developing an electrostatic latent image according to any one of <1> to <7>, wherein the stirring Reynolds number is 6.0×10 4 Above and 9.0×10 5 the following.

[0026] <9> The method for producing a toner for developing an electrostatic latent image according to any one of <1> to <8>, wherein an acidic aqueous solution is added in the welding step.

[0027] <10> The method for producing a toner for developing an electrostatic latent image according to any one of <1> to <9>, wherein a pH in the fusion step is 6 or more and 10 or less.

[0028] <11> The method for producing a toner for electrostatic latent image development according to any one of <1> to <10>, wherein a stirring device including a propeller-type, anchor-type or paddle-type stirring blade and a rotating shaft is used to stir the dispersion during the welding step.

[0029] Effects of the Invention

[0030] According to the invention of <1>, <9> or <11>, there is provided a method for producing a toner for electrostatic latent image development, comprising the steps of: aggregating particles containing binder resin particles in a dispersion to form aggregated particles; and heating the aggregated particles to fuse them, wherein the dispersion is stirred at a Reynolds number of less than 5.0×10 4 or more than 1.0×10 6 Compared with the case of , the image unevenness suppression is excellent.

[0031] According to the invention as set forth in <2>, there is provided a method for producing a toner for developing an electrostatic latent image which is more excellent in suppressing image unevenness than when the η(T) is less than 1,000 Pa·s or exceeds 4,500 Pa·s.

[0032] According to the invention as set forth in <3>, there is provided a method for producing a toner for developing an electrostatic latent image which is more excellent in suppressing image unevenness than when the η(T) is less than 2,000 Pa·s or exceeds 4,500 Pa·s.

[0033] According to the invention described in <4>, there is provided a method for producing a toner for developing an electrostatic latent image which has excellent low-temperature fixing property and better image unevenness suppression property than when the ratio of the crystalline polyester resin contained in the binder resin in the obtained toner particles is less than 15% by mass or exceeds 50% by mass.

[0034] According to the invention described in <5>, there is provided a method for producing a toner for developing an electrostatic latent image which has excellent low-temperature fixing property and is more excellent in suppressing image unevenness than when the ratio of the crystalline polyester resin contained in the binder resin in the obtained toner particles is less than 20% by mass or exceeds 40% by mass.

[0035] According to the invention of <6>, there is provided a method for producing a toner for electrostatic latent image development having better image unevenness suppression performance than when the solid content of the dispersion in the welding step is less than 8% by mass or exceeds 30% by mass.

[0036] According to the invention described in <7>, there is provided a method for producing a toner for electrostatic latent image development having better image unevenness suppression performance than when the temperature of the dispersion in the welding step is lower than the glass transition temperature of the binder resin or exceeds (the glass transition temperature of the binder resin + 40°C).

[0037] According to the invention described in <8>, there is provided a stirring Reynolds number less than 6.0×10 4 or more than 9.0×10 5A method for producing a toner for developing an electrostatic latent image having better image unevenness suppression performance than that of the case of FIG.

[0038] According to the invention <10>, there is provided a method for producing a toner for developing an electrostatic latent image which is more excellent in suppressing image unevenness than when the pH in the fusing step is less than 6 or greater than 10. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Embodiments of the present invention will be described in detail with reference to the following drawings.

[0040] Figure 1 is a schematic structural diagram showing an example of an image forming apparatus used in this embodiment;

[0041] Figure 2 This is a schematic structural diagram showing an example of a process cartridge used in this embodiment.

[0042] Explanation of symbols

[0043] 1Y, 1M, 1C, 1K-photoreceptor (an example of an image holding body), 2Y, 2M, 2C, 2K-charging roller (an example of a charging member), 3-exposure device (an example of an electrostatic latent image forming member), 3Y, 3M, 3C, 3K-laser beam, 4Y, 4M, 4C, 4K-developing device (an example of a developing member), 5Y, 5M, 5C, 5K-primary transfer roller (an example of a primary transfer member), 6Y, 6M, 6C, 6K-photoreceptor cleaning device (an example of a cleaning member), 8Y, 8M, 8C, 8K-toner cartridge, 10Y, 10M, 10C, 10K-image forming unit, 20-intermediate transfer belt (an example of an intermediate transfer body), 22-driving roller, 24 -support roller, 26-secondary transfer roller (an example of a secondary transfer component), 30-intermediate transfer body cleaning device, 107-photosensitive body (an example of an image holding body), 108-charging roller (an example of a charging component), 109-exposure device (an example of an electrostatic latent image forming component), 111-developing device (an example of a developing component), 112-transfer device (an example of a transfer component), 113-photosensitive body cleaning device (an example of a cleaning component), 115-fixing device (an example of a fixing component), 116-mounting guide, 118-opening portion for exposure, 117-frame, 200-processing box, 300-recording paper (an example of a recording medium), P-recording paper (an example of a recording medium). DETAILED DESCRIPTION

[0044] Hereinafter, an embodiment as an example of the present invention will be described in detail.

[0045] Furthermore, within a numerical range described in stages, an upper limit value or a lower limit value described in a certain numerical range may be replaced with an upper limit value or a lower limit value of another numerical range described in stages.

[0046] Furthermore, in the numerical range, the upper limit value or the lower limit value described in a certain numerical range may be replaced with the value shown in the embodiment.

[0047] When a plurality of substances corresponding to each component are present in the composition, the amount of each component in the composition represents the total amount of the plurality of substances present in the composition unless otherwise specified.

[0048] The term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes as long as they can achieve the intended purpose of the process.

[0049] (Method for producing toner for developing electrostatic latent images)

[0050] The method for producing a toner for electrostatic latent image development according to the present embodiment includes the following steps: a step of aggregating particles containing binder resin particles in a dispersion to form aggregated particles; and a step of heating the aggregated particles to fuse them, wherein the dispersion is stirred at a stirring Reynolds number of 5.0×10 4 Above and 1.0×10 6 the following.

[0051] Furthermore, the electrostatic latent image developing toner according to the present embodiment is a toner produced by the method for producing the electrostatic latent image developing toner according to the present embodiment.

[0052] There is a wet production method for producing toner. For example, there is known a method for producing toner in which binder resin particles, release agent particles, etc. are agglomerated using a coagulant such as a metal salt, and the obtained agglomerated particles are heated to be fused.

[0053] In the previous method of manufacturing a toner produced by agglomeration and welding of particles, there is the following problem: due to the contact between particles such as agglomerated particles caused by stirring and the stress caused by stirring, in more detail, in addition to the increase in the number of particle contacts and the increase in the speed at which particles approach, the particles also come into contact with each other due to the stress caused by collision with baffles, etc., resulting in coarse powder.

[0054] In the method for producing a toner for electrostatic latent image development according to the present embodiment, the stirring Reynolds number when the dispersion is stirred during the welding step is 5.0×10 4 Above and 1.0×10 6Next, it is presumed that a toner for developing an electrostatic latent image having excellent image unevenness suppressing property can be obtained as shown below.

[0055] The stirring Reynolds number is an index showing the relationship between the inertial force and the viscous force of a dispersion liquid during stirring.

[0056] 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 increases, and the particles are crushed and aggregated by the impact, resulting in the formation of aggregates.

[0057] Furthermore, if the stirring Reynolds number is too low, the viscosity of the dispersion is strong, and the contact between the particles increases due to insufficient dispersion, resulting in the generation of aggregates.

[0058] In the past, the stirring Reynolds number was usually higher than the above range.

[0059] By setting the stirring Reynolds number when stirring the dispersion in the welding step within the above range, the dispersion is brought into an appropriate stirring and mixing state, and the generation of aggregates as described above can be suppressed.

[0060] Hereinafter, each step will be described in detail.

[0061] <Step of forming aggregated particles>

[0062] The method for producing a toner for electrostatic latent image development according to the present embodiment includes a step of aggregating particles containing binder resin particles in a dispersion to form aggregated particles.

[0063] The dispersion may contain particles such as colorant particles and release agent particles as necessary in addition to the binder resin particles.

[0064] Furthermore, as the binder resin particles, for example, amorphous resin particles and crystalline resin particles are preferably contained.

[0065] The binder resin in the binder resin particles is not particularly limited, but is preferably a polyester resin.

[0066] In the method for producing a toner for electrostatic latent image development involved in the present embodiment, there is no restriction on the proportion of the crystalline resin contained in the binder resin in the obtained toner particles, but from the viewpoint of suppressing the generation of coarse particles and low-temperature fixing property, the proportion of the crystalline resin contained in the binder resin in the obtained toner particles is preferably greater than 15 mass % and less than 50 mass %, and more preferably greater than 20 mass % and less than 40 mass %.

[0067] In the method for producing a toner for electrostatic latent image development involved in the present embodiment, there is no restriction on the proportion of the crystalline polyester resin contained in the binder resin in the obtained toner particles, but from the viewpoint of suppressing the generation of coarse particles, the proportion of the crystalline polyester resin contained in the binder resin in the obtained toner particles and the low-temperature fixing property are preferably 15 mass % or more and 50 mass % or less, and more preferably 20 mass % or more and 40 mass % or less.

[0068] The dispersion is preferably prepared by, for example, mixing a non-crystalline resin particle dispersion, a crystalline resin particle dispersion, a colorant particle dispersion, and a release agent particle dispersion.

[0069] Furthermore, it is preferred that in the dispersion, for example, amorphous resin particles, crystalline resin particles, colorant particles and release agent particles are heterogeneously aggregated to form aggregated particles containing amorphous resin particles, crystalline resin particles, colorant particles and release agent particles and having a diameter close to the diameter of the target toner particles.

[0070] Specifically, for example, a coagulant is added to the dispersion, and the pH of the dispersion is adjusted to be acidic (for example, a pH of 2 or more and 5 or less), and after a dispersion stabilizer is added as needed, the dispersion is heated to a temperature of the glass transition temperature of the resin particles (specifically, for example, a temperature of -30°C or more and -10°C or less of the glass transition temperature of the resin particles) to agglomerate the particles dispersed in the mixed dispersion to form agglomerated particles.

[0071] In the process of forming agglomerated particles, for example, the coagulant may be added at room temperature (e.g., 25° C.) while stirring the dispersion using a rotary shearing homogenizer, the pH of the dispersion may be adjusted to be acidic (e.g., a pH of 2 or more and 5 or less), and a dispersion stabilizer may be added as needed before performing the above-mentioned heating.

[0072] As the coagulant, for example, a surfactant having a polarity opposite to that of the surfactant used as a dispersant added to the dispersion, an inorganic metal salt, and a metal complex having a valence of 2 or more can be cited. In particular, when a metal complex is used as a coagulant, the amount of the surfactant used can be reduced, thereby improving the charging characteristics.

[0073] An additive that forms a complex or similar bond with the metal ion of the coagulant may be used as necessary. As such an additive, a chelating agent may be used.

[0074] Examples of the inorganic metal salt include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate; and inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide.

[0075] As the chelating agent, a water-soluble chelating agent can be used. Examples of the chelating agent include hydroxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid, iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA).

[0076] 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.

[0077] The form of each component contained in the toner particles, such as the binder resin, the release agent, and the colorant, will be reviewed later.

[0078] <Welding process>

[0079] The method for producing a toner for electrostatic latent image development according to the present embodiment includes a step of heating the aggregated particles to fuse them together, wherein the Reynolds number when stirring the dispersion in the fusing step is 5.0×10 4 Above and 1.0×10 6 the following.

[0080] The stirring Reynolds number when stirring the dispersion in the welding step is 5.0×10 4 Above and 1.0×10 6 From the viewpoint of image unevenness suppression, for example, 6.0×10 4 Above and 9.0×10 5 Below, more preferably 7.0×10 4 Above and 5.0×10 5 the following.

[0081] In the present embodiment, the stirring Reynolds number is calculated by the following formula.

[0082] When the length of the stirring blade is l [m], the speed of the tip of the stirring blade is v [m / s], and the specific gravity of the dispersion is ρ [kg / m 3 ], when the viscosity of the dispersion is μ[Pa·s], the Reynolds number Re is calculated by the following formula.

[0083] Re=ρνl / μ

[0084] In this embodiment, the welding step is performed from the time when the dispersion liquid is heated to a temperature not lower than the glass transition temperature of the binder resin and then set within the stirring Reynolds number range to the time when the dispersion liquid is cooled to a temperature lower than the glass transition temperature of the binder resin.

[0085] In the welding process, from the perspective of suppressing image unevenness, for example, it is preferred to maintain the stirring Reynolds number within the range of more than 10 minutes, more preferably to maintain the stirring Reynolds number within the range of more than 20 minutes, further preferably to maintain the stirring Reynolds number within the range of more than 30 minutes and less than 600 minutes, and particularly preferably to maintain the stirring Reynolds number within the range of more than 30 minutes and less than 300 minutes.

[0086] Furthermore, in the welding process, from the viewpoint of suppressing image unevenness, for example, after the dispersion is heated to a temperature above the glass transition temperature of the binder resin, it is preferably set within the range of the stirring Reynolds number within 30 minutes, more preferably within 10 minutes, and particularly preferably within 5 minutes.

[0087] In the method for manufacturing a toner for electrostatic latent image development involved in this embodiment, in the welding process, when the viscosity of the binding resin of the binding resin particles is set to η and the temperature after the heating is set to T, from the perspective of image unevenness suppression, for example, it is preferred to satisfy 1,000Pa·s≤η(T)≤4,500Pa·s, and it is more preferred to satisfy 2,000Pa·s≤η(T)≤4,500Pa·s.

[0088] In addition, η(T) represents the viscosity at temperature T.

[0089] In the method for measuring the viscosity of the binder resin in the present embodiment, a flow tester CFT-500 (manufactured by Shimadzu Corporation) was used with the diameter of the fine hole of the mold set to 1.0 mm and the pressure load set to 10 kgf / cm 2 , set the heating rate to 7°C / min, and the starting temperature to 60°C, and find the temperature that will cause 1cm 3 The viscosity of the sample when it is melted and flows out (melt viscosity).

[0090] The viscosity measured at the temperature T after the temperature increase in the welding step is the above-mentioned η(T).

[0091] From the viewpoint of suppressing image unevenness, the solid content of the dispersion in the welding step is, for example, preferably 8 mass % or more and 30 mass % or less, and more preferably 10 mass % or more and 25 mass % or less.

[0092] In the welding process, the agglomerated particle dispersion in which the agglomerated particles are dispersed is heated to, for example, a temperature above the glass transition temperature of the bonding resin particles, preferably above the glass transition temperature of the bonding resin particles and below (the glass transition temperature of the bonding resin particles + 40°C), more preferably above (the glass transition temperature of the bonding resin particles + 10°C) and below (the glass transition temperature of the bonding resin particles + 30°C), so that the agglomerated particles are welded to form toner particles.

[0093] In the welding process, from the viewpoint of suppressing image unevenness, the peripheral speed of the stirring member such as the stirring blade when stirring the dispersion is preferably, for example, 0.3 m / s to 5.0 m / s, more preferably 0.5 m / s to 4.0 m / s, and particularly preferably 1.0 m / s to 3.0 m / s.

[0094] In the fusion step, from the viewpoint of suppressing image unevenness, the pH of the dispersion liquid is, for example, preferably 6 to 10, more preferably 6.5 to 9, and particularly preferably 7.0 to 8.5.

[0095] In the welding step, from the viewpoint of pH adjustment, for example, an acidic aqueous solution is preferably added to the dispersion.

[0096] From the viewpoint of particle formation and image non-uniformity suppression, the addition of the acidic aqueous solution in the welding process is preferably carried out after the temperature is raised to above the glass transition temperature of the binder resin in the binder resin particles, and more preferably after the stirring Reynolds number is set within the range.

[0097] 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.

[0098] <Stirring device>

[0099] There is no particular limitation on the stirring device used in the step of forming agglomerated particles and the welding step, and a known stirring device can be used. However, a stirring device having stirring blades and a rotating shaft is preferred, and a stirring device having propeller-type, anchor-type or paddle-type stirring blades and a rotating shaft is more preferred.

[0100] Furthermore, the stirring device preferably includes a granulation container (stirring tank) having a temperature control mechanism such as a jacket.

[0101] The stirring blade is not particularly limited, and examples thereof include propeller-type, anchor-type, paddle-type, turbine-type stirring blades, etc. Among them, propeller-type, anchor-type, or paddle-type stirring blades are preferred from the viewpoint of image unevenness suppression.

[0102] In the stirring device, when the stirring blade diameter d (m) and the granulation container inner diameter D (m) are used, the value of d / D is, for example, preferably 0.3 to 0.8, more preferably 0.5 to 0.7.

[0103] Furthermore, from the viewpoint of further exerting the effect of the present embodiment, in the stirring device, the stirring blade diameter d is, for example, preferably 0.2 m or more, and more preferably 0.3 m or more.

[0104] The method for producing the electrostatic latent image developing toner according to the present embodiment may further include known steps other than the step of forming aggregated particles and the step of fusing. Specifically, for example, the steps described below may be included.

[0105] Furthermore, for example, the method for producing a toner for developing an electrostatic latent image according to the embodiment preferably includes a preparation step of preparing toner particles containing an amorphous resin.

[0106] Specifically, for example, the method for producing the electrostatic latent image developing toner according to the present embodiment preferably includes the following steps:

[0107] a step of preparing an amorphous resin particle dispersion in which amorphous resin particles are dispersed and a crystalline resin particle dispersion in which crystalline resin particles are dispersed (resin particle dispersion preparation step);

[0108] the step of forming agglomerated particles;

[0109] After obtaining an aggregated particle dispersion in which the aggregated particles are dispersed, the aggregated particle dispersion and an amorphous resin particle dispersion are mixed to aggregate the amorphous resin particles so that the amorphous resin particles adhere to the surfaces of the aggregated particles, thereby forming second aggregated particles (second aggregated particle step);

[0110] a step of adjusting the pH of the dispersion to stop the progress of aggregation (aggregation stopping step); and

[0111] The welding process.

[0112] Hereinafter, the details of each step will be described.

[0113] In the following description, a method for obtaining toner particles containing a colorant and a release agent is described, but the colorant and the release agent are used as necessary. Of course, other additives besides the colorant and the release agent may also be used.

[0114] -Resin particle dispersion preparation step-

[0115] First, for example, a colorant particle dispersion containing colorant particles and a release agent particle dispersion containing release agent particles are prepared together with resin particle dispersions containing resin particles serving as a binder resin (amorphous resin particle dispersion and crystalline resin particle dispersion).

[0116] Here, the resin particle dispersion is prepared by, for example, dispersing the resin particles in a dispersion medium using a surfactant.

[0117] Examples of the dispersion medium used for the resin particle dispersion include aqueous media.

[0118] Examples of the aqueous medium include water such as distilled water and deionized water, and alcohols, etc. These may be used alone or in combination of two or more.

[0119] Examples of surfactants include anionic surfactants such as sulfate ester 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 polyols. Among them, anionic surfactants and cationic surfactants are particularly useful. Nonionic surfactants may be used together with anionic surfactants or cationic surfactants.

[0120] The surfactant may be used alone or in combination of two or more.

[0121] In the resin particle dispersion, as a method for dispersing the resin particles in the dispersion medium, for example, a conventional dispersion method such as a rotary shearing homogenizer or a ball mill with a medium, a sand mill, a DYNO-MILL, etc. is cited. In addition, depending on the type of the resin particles, for example, the resin particles may be dispersed in the resin particle dispersion using a phase inversion emulsification method.

[0122] In addition, the phase inversion emulsification method refers to the following method: the resin to be dispersed is dissolved in a hydrophobic organic solvent that can dissolve the resin, a base is added to the organic continuous phase (O phase) for neutralization, and then an aqueous medium (W phase) is added to thereby convert the resin from W / O to O / W (the so-called phase inversion), convert it into a discontinuous phase, and thereby disperse the resin into particles in the aqueous medium.

[0123] The volume average particle size of the resin particles dispersed in the resin particle dispersion is, for example, preferably 0.01 μm or more and 1 μm or less, more preferably 0.08 μm or more and 0.8 μm or less, and further preferably 0.1 μm or more and 0.6 μm or less.

[0124] In addition, regarding the volume average particle size of the resin particles, the cumulative distribution of the volume is plotted from the small particle size side using the particle size range (channel) divided by the particle size distribution obtained by the measurement using a laser diffraction particle size distribution measuring device (e.g., manufactured by HORIBA, Ltd., LA-700), and the particle size when the cumulative amount reaches 50% relative to all particles is measured as the volume average particle size D50v. In addition, the volume average particle size of the particles in other dispersions is also measured in the same manner.

[0125] The content of the resin particles in the resin particle dispersion is, for example, preferably 5 mass % or more and 50 mass % or less, and more preferably 10 mass % or more and 40 mass % or less.

[0126] In addition, in the same manner as the resin particle dispersion, for example, a colorant particle dispersion and a release agent particle dispersion are also prepared. That is, the volume average particle size of the particles in the resin particle dispersion, the dispersion medium, the dispersion method, and the content of the particles are also applied to the colorant particles dispersed in the colorant particle dispersion and the release agent particles dispersed in the release agent particle dispersion.

[0127] -Second Aggregate Particle Formation Step-

[0128] 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.

[0129] Then, in the dispersion 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.

[0130] Specifically, for example, in the step of forming aggregated particles, when the aggregated particles reach a target particle size, a dispersion of amorphous resin particles is added to the dispersion of the aggregated particles, and the dispersion is heated below the glass transition temperature of the amorphous resin particles.

[0131] Then, the pH of the dispersion is adjusted to stop the progress of aggregation (aggregation stopping step).

[0132] After the fusion step is completed, 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.

[0133] The washing process is not particularly limited, but from the viewpoint of chargeability, it is preferred to fully perform replacement washing with deionized water. In addition, the solid-liquid separation process is not particularly limited, but from the viewpoint of productivity, it is preferred to perform suction filtration, pressure filtration, etc. In addition, the method of the drying process is not particularly limited, but from the viewpoint of productivity, it is preferred to perform freeze drying, airflow drying, fluidized drying, vibration-type fluidized drying, etc.

[0134] The method for producing the electrostatic latent image developing toner according to the present embodiment preferably includes, for example, a step of adding an external additive to the obtained toner particles.

[0135] As the external addition method, for example, it is preferably carried out by a V mixer, a Henschel mixer, a Lödige mixer, etc. Furthermore, if necessary, coarse particles of the toner may be removed using a vibration sifter, a wind sifter, etc.

[0136] Hereinafter, each component contained in the electrostatic latent image developing toner obtained by the method for producing the electrostatic latent image developing toner according to the present embodiment will be described in detail.

[0137] <Binder resin>

[0138] The binder resin preferably contains an amorphous resin, for example, and more preferably contains an amorphous resin and a crystalline resin from the viewpoint of image strength and suppression of concentration unevenness in the obtained image. That is, in the step of forming the agglomerated particles, the binder resin particles preferably contain amorphous resin particles and crystalline resin particles.

[0139] Furthermore, the toner particles preferably contain, for example, a non-crystalline resin.

[0140] Furthermore, the toner particles are preferably, for example, core-shell type toner particles.

[0141] Here, the amorphous resin refers to a resin that has only a step-like endothermic change but no clear endothermic peak in thermal analysis measurement using differential scanning calorimetry (DSC), and refers to a resin that is solid at room temperature and thermoplasticizes at a temperature above the glass transition temperature.

[0142] On the other hand, a crystalline resin refers to a resin having a clear endothermic peak in differential scanning calorimetry (DSC) and not having a step-like change in endothermic value.

[0143] Specifically, for example, a crystalline resin refers to 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 refers to a resin whose half width exceeds 10°C or a resin in which no clear endothermic peak can be confirmed.

[0144] The amorphous resin will be described.

[0145] Examples of the amorphous resin include known amorphous resins such as amorphous polyester resins, amorphous vinyl resins (e.g., styrene acrylic resins, etc.), epoxy resins, polycarbonate resins, and polyurethane resins. Among them, from the viewpoint of suppressing density unevenness in the obtained image and suppressing white spots, for example, amorphous polyester resins and amorphous vinyl resins (especially styrene acrylic resins) are preferred, and amorphous polyester resins are more preferred.

[0146] Furthermore, it is also a preferred embodiment to use, for example, a non-crystalline polyester resin and a styrene acrylic resin together as the non-crystalline resin.

[0147] Examples of the non-crystalline polyester resin include polycondensates of polycarboxylic acids and polyols. As the non-crystalline polyester resin, a commercially available product may be used, or a synthetic resin may be used.

[0148] Examples of the polycarboxylic acid include aliphatic dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenyl succinic acid, adipic acid, sebacic acid, etc.), alicyclic dicarboxylic acids (e.g., cyclohexane dicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, phthalic acid, naphthalene dicarboxylic acid, etc.), anhydrides thereof, or lower (e.g., carbon number 1 to 5) alkyl esters thereof. Among these, aromatic dicarboxylic acids are preferred as the polycarboxylic acid.

[0149] The polycarboxylic acid may be used together with the dicarboxylic acid to form a trivalent or higher carboxylic acid having a crosslinked structure or a branched structure. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, their anhydrides, or their lower (e.g., carbon number 1 to 5) alkyl esters.

[0150] The polyvalent carboxylic acid may be used alone or in combination of two or more.

[0151] Examples of the polyol 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 them, the polyol is preferably an aromatic diol or an alicyclic diol, and more preferably an aromatic diol.

[0152] As the polyol, a trivalent or higher polyol having a cross-linked structure or a branched structure may be used together with the diol. Examples of the trivalent or higher polyol include glycerol, trimethylolpropane, and pentaerythritol.

[0153] The polyols may be used alone or in combination of two or more.

[0154] The amorphous polyester resin is obtained by a known manufacturing method. Specifically, for example, it is obtained by the following method: the polymerization temperature is set to be above 180°C and below 230°C, the pressure in the reaction system is reduced as needed, and the reaction is allowed to proceed while removing the water and alcohol produced during the condensation. In the case where the monomer of the raw material is insoluble or incompatible at the reaction temperature, a high-boiling-point solvent can be added as a solubilizing agent to dissolve it. In this case, the polycondensation reaction is carried out while the solubilizing agent is removed by distillation. In the case where there are monomers with poor compatibility in the copolymerization reaction, for example, it is preferred to condense the monomers with poor compatibility with the acid or alcohol to be polycondensed with the monomer in advance, and then polycondense with the main component.

[0155] The proportion of the amorphous resin in the total binder resin is, for example, preferably 60% by mass to 98% by mass, more preferably 65% ​​by mass to 95% by mass, and even more preferably 70% by mass to 90% by mass.

[0156] The characteristics of amorphous resin will be described.

[0157] The glass transition temperature (Tg) of the amorphous resin is, for example, preferably 50° C. or higher and 80° C. or lower, and more preferably 50° C. or higher and 65° C. or lower.

[0158] The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), more specifically, according to the "extrapolated glass transition start temperature" described in the method for determining the glass transition temperature in JIS K 7121-1987 "Determination of Transition Temperature of Plastics".

[0159] The weight average molecular weight (Mw) of the non-crystalline resin is, for example, preferably 5,000 or more and 1,000,000 or less, and more preferably 7,000 or more and 500,000 or less.

[0160] The number average molecular weight (Mn) of the amorphous resin is preferably, for example, 2,000 or more and 100,000 or less.

[0161] The molecular weight distribution Mw / Mn of the amorphous resin is, for example, preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less.

[0162] The weight average molecular weight and the number average molecular weight are measured by gel permeation chromatography (GPC). In the molecular weight measurement by GPC, GPC HLC-8120GPC manufactured by TOSOH CORPORATION is used as a measuring device, a column TSKgel SuperHM-M (15 cm) manufactured by TOSOH CORPORATION is used, and tetrahydrofuran (THF) solvent is used. The weight average molecular weight and the number average molecular weight are calculated using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample based on the measurement results.

[0163] From the viewpoint of suppressing the generation of coarse particles, as the amorphous polyester resin, for example, it is preferred to use a polyester resin having a weight average molecular weight of 5,000 to 20,000 and a polyester resin having a weight average molecular weight of more than 20,000 to 1,000,000 at the same time. It is more preferred to use a polyester resin having a weight average molecular weight of 7,000 to 20,000 and a polyester resin having a weight average molecular weight of more than 20,000 to 500,000 at the same time. It is particularly preferred to use a polyester resin having a weight average molecular weight of 7,000 to 20,000 and a polyester resin having a weight average molecular weight of more than 20,000 to 100,000 at the same time.

[0164] The crystalline resin will be described.

[0165] Examples of the crystalline resin include known crystalline resins such as crystalline polyester resins and crystalline vinyl resins (e.g., polyalkylene resins, long-chain (meth) alkyl acrylate resins, etc.). Among them, crystalline polyester resins are preferred from the viewpoint of suppressing uneven density and white spots in the obtained image.

[0166] Examples of the crystalline polyester resin include polycondensates of polycarboxylic acids and polyols. As the crystalline polyester resin, a commercially available product may be used, and a synthetic resin may also be used.

[0167] Since the crystalline polyester resin easily forms a crystal structure, for example, it is preferable to use a polycondensate of a linear aliphatic polymerizable monomer rather than a polycondensate of a polymerizable monomer having an aromatic ring.

[0168] Examples of the polycarboxylic acid 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, and naphthalene-2,6-dicarboxylic acid, etc.), anhydrides thereof, or lower (e.g., having 1 to 5 carbon atoms) alkyl esters thereof.

[0169] The polycarboxylic acid may be used together with the dicarboxylic acid, and a trivalent or higher carboxylic acid having a cross-linked structure or a branched structure. 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, or their lower (e.g., carbon number 1 or more and 5 or less) alkyl esters.

[0170] As the polycarboxylic acid, a dicarboxylic acid having a sulfonic acid group or a dicarboxylic acid having an ethylenic double bond may be used together with these dicarboxylic acids.

[0171] The polyvalent carboxylic acid may be used alone or in combination of two or more.

[0172] Examples of the polyol include aliphatic diols (e.g., linear aliphatic diols having a main chain portion having carbon atoms of 7 or more and 20 or less). Examples of the aliphatic diols include ethylene glycol, 1,3-propylene glycol, 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-docosanediol. Among them, examples of the aliphatic diols include 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol.

[0173] As the polyol, a trivalent or higher alcohol having a cross-linked structure or a branched structure may be used together with the diol. Examples of the trivalent or higher alcohol include glycerol, trimethylolethane, trimethylolpropane, and pentaerythritol.

[0174] The polyols may be used alone or in combination of two or more.

[0175] In the polyol, for example, the content of the aliphatic diol is preferably 80 mol % or more, more preferably 90 mol % or more.

[0176] The melting temperature of the crystalline polyester resin is, for example, preferably 50° C. or higher and 100° C. or lower, more preferably 55° C. or higher and 90° C. or lower, and further preferably 60° C. or higher and 85° C. or lower.

[0177] The melting temperature of the crystalline polyester resin is determined from a DSC curve obtained by differential scanning calorimetry (DSC) in accordance with the "melting peak temperature" described in the method for determining the melting temperature in JIS K7121:1987 "Determination of transition temperatures of plastics".

[0178] The weight average molecular weight (Mw) of the crystalline polyester resin is preferably, for example, 6,000 or more and 35,000 or less.

[0179] Similar to the amorphous polyester resin, the crystalline polyester resin can be obtained by, for example, a known production method.

[0180] The crystalline polyester resin is preferably a polymer of an α,ω-linear aliphatic dicarboxylic acid and an α,ω-linear aliphatic diol, for example, from the viewpoint of easily forming a crystal structure and having good compatibility with a non-crystalline polyester resin, thereby improving image fixability.

[0181] As the α,ω-straight-chain aliphatic dicarboxylic acid, for example, an α,ω-straight-chain aliphatic dicarboxylic acid in which the alkylene group connecting two carboxyl groups has 3 to 14 carbon atoms is preferred, the alkylene group has more preferably 4 to 12 carbon atoms, and the alkylene group has even more preferably 6 to 10 carbon atoms.

[0182] Examples of the α,ω-straight-chain aliphatic dicarboxylic acid include succinic acid, glutaric acid, adipic acid, 1,6-hexanedicarboxylic acid (common name suberic acid), 1,7-heptanedicarboxylic acid (common name azelaic acid), 1,8-octanedicarboxylic acid (common name sebacic acid), 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, and 1,18-octadecanedicarboxylic acid. Among them, 1,6-hexanedicarboxylic acid, 1,7-heptanedicarboxylic acid, 1,8-octanedicarboxylic acid, 1,9-nonanedicarboxylic acid, and 1,10-decanedicarboxylic acid are preferred.

[0183] The α,ω-straight-chain aliphatic dicarboxylic acids may be used alone or in combination of two or more.

[0184] As the α,ω-straight-chain aliphatic diol, for example, an α,ω-straight-chain aliphatic diol having 3 to 14 carbon atoms in an alkylene group connecting two hydroxyl groups is preferred, the carbon number of the alkylene group is more preferably 4 to 12 carbon atoms, and the carbon number of the alkylene group is further preferably 6 to 10 carbon atoms.

[0185] Examples of the α,ω-straight-chain aliphatic diol include ethylene glycol, 1,3-propylene glycol, 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. Among them, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol are preferred.

[0186] The α,ω-straight-chain aliphatic diol may be used alone or in combination of two or more.

[0187] As the polymer of α,ω-straight-chain aliphatic dicarboxylic acid and α,ω-straight-chain aliphatic diol, from the viewpoint of easy formation of a crystal structure and good compatibility with a non-crystalline polyester resin, and as a result, from the viewpoint of improved image fixability, for example, 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 them, a polymer of 1,10-decanedicarboxylic acid and 1,6-hexanediol is more preferred.

[0188] Other bonding resins

[0189] 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.), or copolymers of two or more of these monomers.

[0190] In addition, examples of the binder resin include non-vinyl resins such as epoxy resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and modified rosins, mixtures thereof with the vinyl resins, or graft polymers obtained by polymerizing vinyl monomers under the coexistence of the non-vinyl resins.

[0191] These binder resins may be used alone or in combination of two or more.

[0192] The content of the binder resin is, for example, preferably 40 mass % to 95 mass % inclusive, more preferably 50 mass % to 90 mass % inclusive, and further preferably 60 mass % to 85 mass % inclusive, based on the entire toner particles.

[0193] -Release agent-

[0194] Examples of the release agent include hydrocarbon waxes, natural waxes such as carnauba wax, rice wax, and candelilla wax, synthetic waxes such as montan wax, or mineral / petroleum waxes, and ester waxes such as fatty acid esters and montanic acid esters. The release agent is not limited thereto.

[0195] As a release agent, from the viewpoint of suppressing uneven concentration and white spots in the obtained image, having good compatibility with the amorphous polyester resin, and thus improving the fixability of the image, for example, an ester wax is preferred, and more preferably an ester wax of a higher fatty acid having 10 to 30 carbon atoms and a monovalent or polyvalent alcohol component having 1 to 30 carbon atoms.

[0196] The ester wax is a wax having an ester bond. The ester wax may be any of monoesters, diesters, triesters, and tetraesters, and any known natural or synthetic ester wax may be used.

[0197] Examples of the ester wax include ester compounds of higher fatty acids (fatty acids having 10 or more carbon atoms, etc.) and monovalent or polyvalent aliphatic alcohols (aliphatic alcohols having 8 or more carbon atoms, etc.), and ester compounds having a melting temperature of 60°C to 110°C (for example, preferably 65°C to 100°C, more preferably 70°C to 95°C).

[0198] Examples of the ester wax 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, octanol, lauryl alcohol, myristyl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol; and polyhydric alcohols such as glycerol, ethylene glycol, propylene glycol, sorbitol, and pentaerythritol). Specific examples include carnauba wax, rice bran wax, candelilla wax, jojoba oil, wood wax, beeswax, white wax, lanolin, and montanic acid ester wax.

[0199] The melting temperature of the release agent is, for example, preferably 50° C. or higher and 110° C. or lower, and more preferably 60° C. or higher and 100° C. or lower.

[0200] 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 the melting temperature in JIS K7121:1987 "Determination of Transition Temperatures of Plastics".

[0201] The content of the releasing agent is, for example, preferably 1 mass % or more and 20 mass % or less, and more preferably 5 mass % or more and 15 mass % or less, based on the entire toner particles.

[0202] -Colorants-

[0203] In the aggregation step, the dispersion liquid preferably further contains colorant particles, for example.

[0204] Examples of the colorant include various pigments such as carbon black, chrome yellow, Hansa yellow, benzidine yellow, vat yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, vulcan orange, magenta, permanent red, brilliant carmine 3B, brilliant carmine 6B, Dupont Oil Red, pyrazolone red, litho red, rhodamine B lake, lake red C, pigment red, rose Bengal, aniline blue, ultramarine blue, copper oil blue, methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, and malachite green oxalate; and various dyes such as acridine-based, xanthene-based, azo-based, benzoquinone-based, azine-based, anthraquinone-based, thioindigo-based, dioxazine-based, thiazine-based, azomethine-based, indigo-based, phthalocyanine-based, nigrosine-based, polymethine-based, triphenylmethane-based, diphenylmethane-based, and thiazole-based.

[0205] The coloring agent may be used alone or in combination of two or more.

[0206] The colorant may be a surface-treated colorant as required, or may be used together with a dispersant. Furthermore, multiple colorants may be used together.

[0207] The content of the colorant is, for example, preferably 1 mass % to 30 mass % inclusive, and more preferably 3 mass % to 15 mass % inclusive, based on the entire toner particles.

[0208] -Other additives-

[0209] Examples of other additives include well-known additives such as magnetic materials, charge control agents, and inorganic powders. These additives are contained in the toner particles as internal additives.

[0210] -Characteristics of toner particles, etc.-

[0211] The toner particles may be so-called core-shell toner particles (core-shell type particles) composed of a core (core particle) and a coating layer (shell layer) covering the core. The core-shell toner particles 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.

[0212] In the case of toner particles with a core-shell structure, from the viewpoint of suppressing deformation of the toner particles, the average thickness of the shell layer is, for example, preferably greater than 120 nm, more preferably greater than 130 nm, further preferably greater than 140 nm, and preferably less than 550 nm, more preferably less than 500 nm, further preferably less than 400 nm.

[0213] The average thickness of the shell layer is measured by the following method.

[0214] The toner particles are embedded in epoxy resin, sliced ​​with 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 with a scanning electron microscope (SEM). Ten toner particle cross sections are randomly selected from the SEM image, and the shell thickness of 20 locations of each toner particle is measured, and the average value is calculated, and the average value of the ten toner particles is taken as the average thickness.

[0215] The volume average particle diameter (D50v) of the toner is, for example, preferably 2 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less.

[0216] The volume average particle size of the toner is measured using Coulter Multisizer II (manufactured by Beckman Instruments Inc.), and the volume average particle size of the electrolyte is measured using ISOTON-II (manufactured by Beckman Instruments Inc.).

[0217] During measurement, 0.5 mg to 50 mg of the measurement sample is added to 2 mL of a 5% by mass aqueous solution of a surfactant (preferably sodium alkylbenzene sulfonate) as a dispersant, and this is added to 100 mL to 150 mL of the electrolyte.

[0218] The electrolyte in which the sample was suspended was dispersed for 1 minute using an ultrasonic disperser, and the particle size of each particle in the range of 2 μm to 60 μm was measured using a Coulter Multisizer II with an aperture of 100 μm. The number of particles to be sampled was 50,000.

[0219] The measured particle diameters were plotted as cumulative distributions based on volume from the smaller diameter side, and the particle diameter when the cumulative distribution reached 50% was defined as the volume average particle diameter D50v.

[0220] In the present embodiment, there is no particular limitation on the average circularity of the toner particles, but from the viewpoint of improving the cleanability of the toner from the image holder, it is preferably 0.91 to 0.98, more preferably 0.94 to 0.98, and even more preferably 0.95 to 0.97.

[0221] In the present embodiment, the circularity of the toner particles is (the circumference of a circle having the same area as the particle projection image) ÷ (the circumference of the particle projection image), and the average circularity of the toner particles is the circularity when the distribution of circularity is accumulated from the smaller side to 50%. The average circularity of the toner particles is obtained by analyzing at least 3,000 toner particles using a flow-type particle image analyzer.

[0222] The average circularity of the toner particles can be controlled by adjusting, for example, the stirring speed of the dispersion in the melting step, the temperature of the dispersion, or the retention time of the dispersion.

[0223] The amount of the release agent on the surface of the toner particles can be controlled by, for example, the amount of the release agent added, the type of the release agent, the adjustment of the temperature during melt kneading, and the surface treatment with hot air after pulverization.

[0224] -External Additives-

[0225] The toner produced by the method for producing the electrostatic latent image developing toner according to the present embodiment may contain an external additive as necessary.

[0226] Furthermore, the toner produced by the method for producing the electrostatic latent image developing toner according to the present embodiment may be toner particles having no external additive or may be toner particles to which an external additive is added.

[0227] 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, K2O·(TiO2) n , Al2O3·2SiO2, CaCO3, MgCO3, BaSO4, MgSO4, etc.

[0228] The surface of the inorganic particles as an external additive is preferably subjected to a hydrophobic treatment, for example. The hydrophobic treatment is carried out, for example, by immersing the inorganic particles in a hydrophobic treatment agent. The hydrophobic treatment agent is not particularly limited, and for example, a silane coupling agent, silicone oil, a titanate coupling agent, an aluminum coupling agent, etc. can be cited. They can be used alone or in combination of two or more.

[0229] The amount of the hydrophobizing agent is preferably, for example, 1 part by mass or more and 10 parts by mass or less relative to 100 parts by mass of the inorganic particles.

[0230] Examples of the external additives include resin particles (polystyrene, polymethyl methacrylate (PMMA), melamine resin and other resin particles), cleaning aids (for example, metal salts of higher fatty acids represented by zinc stearate, and particles of fluorine-based high molecular weight bodies).

[0231] The amount of the external additive added is, for example, preferably 0.01% by mass or more and 10% by mass or less, and more preferably 0.01% by mass or more and 6% by mass or less, based on the toner particles.

[0232] <Electrostatic latent image developer>

[0233] The electrostatic latent image developer according to the present embodiment contains at least a toner manufactured by the method for manufacturing an electrostatic latent image developing toner according to the present embodiment.

[0234] The electrostatic latent image developer according to the present embodiment may be a single-component developer containing only a toner produced by the method for producing an electrostatic latent image developing toner according to the present embodiment, or may be a two-component developer in which the toner and a carrier are mixed.

[0235] The carrier is not particularly limited, and known carriers may be used. Examples of the carrier include a coated carrier in which the surface of a core material composed of magnetic powder is coated with a coating resin; a magnetic powder dispersed carrier in which magnetic powder is dispersed in a matrix resin; a resin impregnated carrier in which porous magnetic powder is impregnated with a resin; and the like.

[0236] Furthermore, the magnetic powder dispersed carrier and the resin impregnated carrier may be a carrier in which the constituent particles of the carrier are used as a core material and the core material is coated with a coating resin.

[0237] Examples of the magnetic powder include magnetic metals such as iron, nickel, and cobalt, and magnetic oxides such as ferrite and magnetite.

[0238] Examples of the coating resin and the base resin include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylate copolymer, a straight-chain silicone resin containing an organic siloxane bond or a modified product thereof, a fluororesin, a polyester, a polycarbonate, a phenolic resin, an epoxy resin, and the like.

[0239] Furthermore, the coating resin and the matrix resin may contain other additives such as conductive particles.

[0240] 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.

[0241] Here, in order to coat the surface of the core material with coating resin, a coating layer formed by dissolving the coating resin and various additives added as required in a suitable solvent can be enumerated, and a method of coating with a solution etc. can be enumerated. As solvent, there is no particular limitation, and selection can be made considering the coating resin used, coating adaptability, etc.

[0242] Specific resin coating methods include an immersion method in which the core material is immersed in a coating layer forming solution, a spraying method in which the coating layer forming solution is sprayed onto the surface of the core material, a fluidized bed method in which the coating layer forming solution is sprayed while the core material is floating by flowing air, and a kneading coating method in which the core material of the carrier and the coating layer forming solution are mixed in a kneading coater and the solvent is removed.

[0243] The mixing ratio (mass ratio) of the toner and the carrier in the two-component developer is, for example, preferably toner:carrier=1:100 to 30:100, and more preferably 3:100 to 20:100.

[0244] <Image forming apparatus / image forming method>

[0245] The image forming apparatus and the image forming method according to the present embodiment will be described.

[0246] The image forming apparatus according to the present embodiment comprises: an image holder; a charging member for charging the surface of the image holder; an electrostatic latent image forming member for forming an electrostatic latent image on the surface of the charged image holder; a developing member for containing an electrostatic latent image developer and developing the electrostatic latent image formed on the surface of the image holder into a toner image using the electrostatic latent image developer; a transfer member for transferring the toner image formed on the surface of the image holder to the surface of a recording medium; and a fixing member for fixing the toner image transferred to the surface of the recording medium. As the electrostatic latent image developer, the electrostatic latent image developer according to the present embodiment can be applied.

[0247] In the image forming device involved in the present embodiment, an image forming method (the image forming method involved in the present embodiment) is implemented, which includes the following steps: a charging step for charging the surface of the image retaining body; an electrostatic latent image forming step for forming an electrostatic latent image on the surface of the charged image retaining body; a developing step for developing the electrostatic latent image formed on the surface of the image retaining body into a toner image using the electrostatic latent image developer involved in the present embodiment; a transfer step for transferring the toner image formed on the surface of the image retaining body onto the surface of the recording medium; and a fixing step for fixing the toner image transferred to the surface of the recording medium.

[0248] The image forming device involved in this embodiment is applicable to the following well-known image forming devices: a device of a direct transfer method that directly transfers the toner image formed on the surface of the image retaining body to a recording medium; a device of an intermediate transfer method that transfers the toner image formed on the surface of the image retaining body to the surface of the intermediate transfer body for the first time, and transfers the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium for the second time; a device equipped with a cleaning member for cleaning the surface of the image retaining body before charging after the toner image is transferred; and a device equipped with a de-staticizing member for de-staticizing the surface of the image retaining body by irradiating de-staticizing light to the surface of the image retaining body after the toner image is transferred and before charging, etc.

[0249] Among them, an image forming apparatus including a cleaning member for cleaning the surface of an image holding member can be mentioned. In addition, as the cleaning member, for example, a cleaning blade is preferable.

[0250] In the case of an intermediate transfer method device, the transfer component, for example, is preferably a structure having the following components: an intermediate transfer body, which transfers the toner image to the surface; a primary transfer component, which transfers the toner image formed on the surface of the image holding body to the surface of the intermediate transfer body; and a secondary transfer component, which transfers the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium for the second time.

[0251] In addition, in the image forming apparatus of the present embodiment, for example, the portion including the developing member may be a box structure (processing box) that is detachable from the image forming apparatus. As the processing box, for example, a processing box having a developing member that accommodates the electrostatic latent image developer of the present embodiment is preferably used.

[0252] Hereinafter, an example of the image forming apparatus according to the present embodiment is shown, but the present invention is not limited thereto. In addition, the main parts shown in the drawings are described, and the description of other parts is omitted.

[0253] Figure 1 It is a diagram schematically showing the structure of the image forming apparatus according to the present embodiment.

[0254] Figure 1 The image forming apparatus shown in the figure includes first to fourth image forming units 10Y, 10M, 10C, 10K (image forming members) of an electrophotographic method for outputting color images of yellow (Y), magenta (M), cyan (C), and black (K) based on color-separated image data. These image forming units (hereinafter, sometimes referred to as "units") 10Y, 10M, 10C, 10K are arranged in parallel with each other at a predetermined distance in the horizontal direction. In addition, these units 10Y, 10M, 10C, 10K may be process cartridges that are attached to and detached from the image forming apparatus.

[0255] In the drawings, an intermediate transfer belt 20 as an intermediate transfer body is extended above each unit 10Y, 10M, 10C, and 10K through each unit. The intermediate transfer belt 20 is arranged to be wound around a driving roller 22 and a support roller 24 that is in contact with the inner surface of the intermediate transfer belt 20, which are arranged in a manner spaced from each other in the direction from left to right in the figure, and to travel in the direction from the first unit 10Y to the fourth unit 10K. In addition, the support roller 24 is urged in a direction away from the driving roller 22 by a spring or the like (not shown), thereby applying tension to the intermediate transfer belt 20 wound around the two. In addition, an intermediate transfer body cleaning device 30 is provided on the image holding body side of the intermediate transfer belt 20 so as to face the driving roller 22.

[0256] Toners of four colors, namely yellow, magenta, cyan and black, contained in toner boxes 8Y, 8M, 8C and 8K are respectively supplied to the developing devices (developing components) 4Y, 4M, 4C and 4K of the respective units 10Y, 10M, 10C and 10K.

[0257] The first to fourth units 10Y, 10M, 10C, and 10K have the same structure, so the first unit 10Y disposed on the upstream side in the traveling direction of the intermediate transfer belt for forming a yellow image will be described as a representative. In addition, the description of the second to fourth units 10M, 10C, and 10K will be omitted by assigning reference numerals representing magenta (M), cyan (C), and black (K) to the same parts as the first unit 10Y instead of yellow (Y).

[0258] The first unit 10Y has a photoreceptor 1Y that functions as an image holder. The following are arranged in order around the photoreceptor 1Y: a charging roller (an example of a charging member) 2Y that charges the surface of the photoreceptor 1Y to a predetermined potential; an exposure device (an example of an electrostatic latent image forming member) 3 that forms an electrostatic latent image by exposing the charged surface using a laser beam 3Y based on a color-separated image signal; a developing device (an example of a developing member) 4Y that supplies charged toner to the electrostatic latent image to develop the electrostatic latent image; a primary transfer roller (an example of a primary transfer member) 5Y that transfers the developed toner image to the intermediate transfer belt 20; and a photoreceptor cleaning device (an example of a cleaning member) 6Y that removes the toner remaining on the surface of the photoreceptor 1Y after the primary transfer.

[0259] In addition, the primary transfer roller 5Y is arranged inside the intermediate transfer belt 20 and is set at a position opposite to the photoreceptor 1Y. Furthermore, each of the primary transfer rollers 5Y, 5M, 5C, and 5K is connected to a bias power supply (not shown) for applying a primary transfer bias. Each bias power supply can change the transfer bias applied to each primary transfer roller under the control of a control unit (not shown).

[0260] Next, the operation of forming a yellow image in the first unit 10Y will be described.

[0261] First, before the operation is performed, the surface of the photoreceptor 1Y is charged to a potential of -600 V to -800 V by the charging roller 2Y.

[0262] The photoreceptor 1Y is conductive (for example, volume resistivity at 20° C.: 1×10 -6 The photosensitive layer is formed by laminating a photosensitive layer on a substrate with a resistance of 100 Ω·cm or less. Usually, the photosensitive layer has a high resistance (resistance of a general resin), but has a property that the resistivity of the portion irradiated with the laser beam changes when the laser beam 3Y is irradiated. Therefore, according to the yellow image data sent from the control unit not shown, the laser beam 3Y is output to the surface of the charged photoreceptor 1Y via the exposure device 3. The laser beam 3Y is irradiated to the photosensitive layer on the surface of the photoreceptor 1Y, thereby forming an electrostatic latent image of the yellow image pattern on the surface of the photoreceptor 1Y.

[0263] An electrostatic latent image refers to an image formed on the surface of the photoreceptor 1Y by charging, and is a so-called negative latent image. It is formed as follows: a laser beam 3Y is used to reduce the resistivity of the irradiated portion of the photosensitive layer, thereby allowing the charged charge on the surface of the photoreceptor 1Y to flow, while on the other hand, the charge on the portion not irradiated by the laser beam 3Y remains.

[0264] The electrostatic latent image formed on the photoreceptor 1Y rotates to a preset development position as the photoreceptor 1Y travels. At the development position, the electrostatic latent image on the photoreceptor 1Y is visualized (developed) as a toner image by the developing device 4Y.

[0265] The developing device 4Y contains, for example, an electrostatic latent image developer containing at least a yellow toner and a carrier. The yellow toner is frictionally charged by being stirred inside the developing device 4Y, and is held on a developer roller (an example of a developer holding member) with a charge of the same polarity (negative polarity) as the charge on the photoreceptor 1Y. Then, by passing the surface of the photoreceptor 1Y through the developing device 4Y, the yellow toner is electrostatically attached to the decharged latent image portion on the surface of the photoreceptor 1Y, thereby developing the latent image with the yellow toner. The photoreceptor 1Y formed with the yellow toner image continues to travel at a preset speed, so that the toner image developed on the photoreceptor 1Y is conveyed to a preset primary transfer position.

[0266] When the yellow toner image on the photoreceptor 1Y is transferred to the primary transfer position, a primary transfer bias is applied to the primary transfer roller 5Y, and an electrostatic force from the photoreceptor 1Y toward the primary transfer roller 5Y acts on the toner image, so that the toner image on the photoreceptor 1Y is transferred to the intermediate transfer belt 20. The transfer bias applied at this time has a polarity (+) opposite to the polarity (-) of the toner, and is controlled to +10 μA by a control unit (not shown) in the first unit 10Y, for example.

[0267] On the other hand, the toner remaining on the photoreceptor 1Y is removed and recovered by the photoreceptor cleaning device 6Y.

[0268] Furthermore, the primary transfer bias applied to the primary transfer rollers 5M, 5C, and 5K after the second unit 10M is also controlled based on the first unit.

[0269] In this manner, the intermediate transfer belt 20 to which the yellow toner image has been transferred by the first unit 10Y is transported sequentially through the second to fourth units 10M, 10C, and 10K, and transfers are performed multiple times so that the toner images of the respective colors are superimposed.

[0270] After the toner images of four colors have been transferred multiple times by the first to fourth units, the intermediate transfer belt 20 reaches the secondary transfer section composed of the intermediate transfer belt 20, the support roller 24 in contact with the inner surface of the intermediate transfer belt, and the secondary transfer roller (an example of the secondary transfer member) 26 arranged on the image holder side of the intermediate transfer belt 20. On the other hand, at a preset timing, the recording paper (an example of the recording medium) P is supplied to the gap between the secondary transfer roller 26 and the intermediate transfer belt 20 through the supply mechanism, and the secondary transfer bias is applied to the support roller 24. The transfer bias applied at this time has the same polarity (-) as the polarity (-) of the toner, and the 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 to the recording paper P. In addition, the secondary transfer bias at this time is determined based on the resistance detected by the resistance detection member (not shown) that detects the resistance of the secondary transfer section, and is voltage-controlled.

[0271] Then, the recording paper P is conveyed to a pressure-contact portion (nip portion) of a pair of fixing rollers of a fixing device (an example of a fixing member) 28 , and the toner image is fixed to the recording paper P, thereby forming a fixed image.

[0272] Examples of the recording paper P to which the toner image is transferred include plain paper used in electrophotographic copy machines, printers, etc. Examples of the recording medium other than the recording paper P include OHP sheets and the like.

[0273] In order to further improve the smoothness of the image surface after fixing, for example, the surface of the recording paper P is preferably smooth, and for example, coated paper obtained by coating the surface of ordinary paper with a resin or the like, coated paper for printing, etc. are preferably used.

[0274] The recording paper P on which the color image has been fixed is conveyed to the discharge portion, thereby completing a series of color image forming operations.

[0275] <Process Cartridge / Toner Cartridge>

[0276] A process cartridge according to this embodiment will be described.

[0277] The process cartridge according to the present embodiment includes a developing member that contains the electrostatic latent image developer according to the present embodiment and develops the electrostatic latent image formed on the surface of the image holding member into a toner image using the electrostatic latent image developer, and is attached to and detached from the image forming apparatus.

[0278] In addition, the processing box involved in this embodiment is not limited to the above-mentioned structure, but can also be a structure having a developing device and at least one component selected from other components set as needed, such as an image retaining body, a charging component, an electrostatic latent image forming component and a transfer component.

[0279] Hereinafter, an example of the process cartridge according to the present embodiment is shown, but the present invention is not limited thereto. In addition, the main parts shown in the drawings are described, and the description of other parts is omitted.

[0280] Figure 2 It is a diagram schematically showing the structure of a process cartridge according to the present embodiment.

[0281] Figure 2 The processing box 200 shown is, for example, constructed by combining and holding a photosensitive body 107 (an example of an image holding body), a charging roller 108 (an example of a charging component) arranged around the photosensitive body 107, a developing device 111 (an example of a developing component) and a photosensitive body cleaning device 113 (an example of a cleaning component) into an integral body through a frame 117 provided with a mounting guide 116 and an opening portion 118 for exposure, thereby forming a box.

[0282] in addition, Figure 2 109 denotes an exposure device (an example of an electrostatic latent image forming member), 112 denotes a transfer device (an example of a transfer member), 115 denotes a fixing device (an example of a fixing member), and 300 denotes recording paper (an example of a recording medium).

[0283] Next, a toner cartridge according to the present embodiment will be described.

[0284] The toner cartridge according to the present embodiment is a toner cartridge that contains the toner according to the present embodiment and is attached to and detached from an image forming apparatus. The toner cartridge contains replenishing toner for supplying to a developing member provided in the image forming apparatus.

[0285] in addition, Figure 1 The image forming apparatus shown is an image forming apparatus having a structure for attaching and detaching toner cartridges 8Y, 8M, 8C, and 8K, 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 in the figure. When the toner contained in the toner cartridge becomes less, the toner cartridge is replaced.

[0286] Example

[0287] 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. In addition, "parts" and "%" indicating amounts are based on mass unless otherwise specified.

[0288] (Example 1)

[0289] -Preparation of amorphous polyester resin (A)-

[0290] Dimethyl adipate: 74 parts

[0291] Dimethyl terephthalate: 192 parts

[0292] Bisphenol A ethylene oxide adduct: 216 parts

[0293] Ethylene glycol: 38 parts

[0294] Tetrabutoxy titanate (catalyst): 0.037 parts

[0295] The above components were placed in a heated and dried two-necked flask, nitrogen was introduced into the container to maintain an inert atmosphere, and the temperature was raised while stirring, and then a co-condensation reaction was carried out at 160°C for 7 hours, and then the pressure was gradually reduced to 10 Torr while the temperature was raised to 220°C and maintained for 4 hours. The pressure was temporarily returned to normal pressure, 9 parts of trimellitic anhydride was added, and the pressure was gradually reduced to 10 Torr again and maintained for 1 hour, thereby synthesizing a polyester resin (A).

[0296] The glass transition temperature of the obtained polyester resin (A) was measured by differential scanning calorimetry (DSC) by the above-mentioned method and was 65° C. The molecular weight of the obtained polyester resin (A) was measured by GPC by the above-mentioned method and was found to have a weight average molecular weight of 12,000.

[0297] -Preparation of amorphous polyester resin particle dispersion (A)-

[0298] Polyester resin (A): 160 parts

[0299] Ethyl acetate: 233 parts

[0300] Sodium hydroxide aqueous solution (0.3 mol / L): 0.1 part

[0301] The above components were placed in a separable flask, heated at 70°C, and stirred using a THREE-ONE MOTOR (manufactured by SHINTO Scientific Co., Ltd.) to prepare a resin mixed solution. While further stirring the resin mixed solution, 500 parts of deionized water were gradually added to emulsify the phase, 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.

[0302] -Preparation of amorphous polyester resin (B)-

[0303] Bisphenol A ethylene oxide 2 mole adduct: 114 parts

[0304] Bisphenol A propylene oxide 2 mole adduct: 84 parts

[0305] Dimethyl terephthalate: 75 parts

[0306] Dodecenylsuccinic acid: 19.5 parts

[0307] Trimellitic acid: 7.5 parts

[0308] The above components were placed in a volume flask equipped with a stirring device, a nitrogen inlet pipe, a temperature sensor and a distillation tower, and the temperature was raised to 190°C over 1 hour. After stirring the reaction system, 3.0 parts of dibutyltin oxide was added. Furthermore, the temperature was raised from 190°C to 240°C over 6 hours while distilling off the generated water, and a dehydration condensation reaction was further continued at 240°C for 2 hours to synthesize a polyester resin (B). The obtained polyester resin (B) had a glass transition temperature of 57°C and a weight average molecular weight of 58,000.

[0309] -Preparation of amorphous polyester resin particle dispersion (B)-

[0310] Polyester resin (B): 160 parts

[0311] Ethyl acetate: 233 parts

[0312] Sodium hydroxide aqueous solution (0.3 mol / L): 0.1 part

[0313] The above components were placed in a separable flask, heated at 70°C, and stirred using a THREE-ONE MOTOR (manufactured by SHINTO Scientific Co., Ltd.) to prepare a resin mixed solution. While further stirring the resin mixed solution, 500 parts of deionized water were gradually added to emulsify the phase, 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.

[0314] -Preparation of Crystalline Polyester Resin (C)-

[0315] Dimethyl sebacate: 98 parts

[0316] ·Sodium 5-sulfonate dimethyl isophthalate: 20 parts

[0317] 1,5-Pentanediol: 100 parts

[0318] Dibutyltin oxide (catalyst): 0.3 parts

[0319] The above components were placed in a separable flask, and the air in the container was set to an inert atmosphere with nitrogen by decompression operation, and stirred and refluxed at 180°C for 5 hours using a THREE-ONE MOTOR (manufactured by SHINTO Scientific Co., Ltd.). Thereafter, the temperature was gradually raised to 230°C under reduced pressure, and stirred for 2 hours. When it 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.

[0320] -Preparation of Crystalline Polyester Resin Particle Dispersion (C)-

[0321] Crystalline polyester resin (C): 90 parts

[0322] Anionic surfactant (manufactured by DKS Co. Ltd., NEOGEN RK): 1.8 parts

[0323] Deionized water: 210 parts

[0324] The above components were mixed and heated to 100° C., dispersed using a homogenizer (ULTRA TURRAX T50 manufactured by IKA), and then dispersed using a pressure jet type Gaulin homogenizer for 1 hour to prepare a crystalline polyester resin particle dispersion (C) having a volume average particle size of 200 nm (solid content concentration: 20%).

[0325] -Preparation of Release Agent Particle Dispersion (W)-

[0326] Paraffin wax (manufactured by NIPPON SEIRO CO., LTD., FNP0090): 100 parts

[0327] Anionic surfactant (manufactured by DKS Co. Ltd., NEOGEN RK): 1.0 part

[0328] Deionized water: 400 parts

[0329] The above components were mixed and heated to 95°C, and dispersed using a homogenizer (ULTRA TURRAX T50 manufactured by IKA Co., Ltd.) and dispersed using a pressure jet type Gaulin homogenizer for 3 hours to prepare a release agent particle dispersion (W) having a volume average particle size of 240 nm (solid content concentration: 20%).

[0330] -Preparation of Colorant Particle Dispersion (K)-

[0331] Carbon black (Regal 330 manufactured by Cabot Corporation): 50 parts

[0332] Ionic surfactant NEOGEN RK (manufactured by DKS Co. Ltd.): 5 parts

[0333] Deionized water: 192.9 parts

[0334] The above components were mixed and treated at 240 MPa for 10 minutes using ULTIMAIZER (manufactured by Sugino Machine Limited) to prepare a colorant particle dispersion (K) (solid content concentration: 20% by mass).

[0335] <Step of forming aggregated particles>

[0336] Deionized water: 5000 parts

[0337] Amorphous polyester resin particle dispersion (A): 2000 parts

[0338] Amorphous polyester resin particle dispersion (B): 2000 parts

[0339] Crystalline polyester resin particle dispersion (C): 4000 parts

[0340] Release agent particle dispersion (W): 1500 parts

[0341] Colorant particle dispersion (K): 1500 parts

[0342] The above materials were placed in a circulation reaction tank equipped with four paddle-type stirring blades, and 0.1 N (=0.1 mol / L) nitric acid was added to adjust the pH to 3.8.

[0343] An aluminum sulfate aqueous solution was prepared by dissolving 15 parts of aluminum sulfate in 1000 parts of deionized water. While the contents were circulated in the circulation reaction tank and stirred and dispersed, the aluminum sulfate aqueous solution was added from the inlet. Then, the contents were circulated for 10 minutes while maintaining 30° C., stirred and dispersed.

[0344] Next, the disperser was stopped, the bottom valve at the bottom of the stirring tank was closed, and 3000 parts of deionized water was added from the inlet, and then added into the stirring tank via the disperser and the conduit, and stirred and mixed into the dispersion.

[0345] Next, the contents were heated to 45° C. using a jacket while continuing to stir, and the temperature was maintained until the volume average particle size of the aggregated particles reached 4.0 μm.

[0346] <Second Aggregation Step>

[0347] A mixed solution of 2000 parts of the amorphous polyester resin particle dispersion (A) and 2000 parts of the amorphous polyester resin particle dispersion (B) was placed in a stirring tank and maintained for 30 minutes to obtain a dispersion containing second aggregated particles.

[0348] <Agglutination stopping process>

[0349] 200 parts of EDTA (ethylenediaminetetraacetic acid) was added to the dispersion containing the second aggregated particles, and then a 1N (=1 mol / L) sodium hydroxide aqueous solution was added to adjust the pH to 9, which was maintained for 5 minutes.

[0350] <Welding process>

[0351] While continuing to stir the stirring tank, the temperature was raised to 85°C at a heating rate of 0.5°C / min and the stirring Reynolds number was 1.0×10 5 Then, 100 parts of an acidic aqueous solution was added and kept at pH 7.6 for 3 hours. Then, 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), kept for 30 minutes, and then cooled to 30°C at 0.5°C / min (second cooling).

[0352] <Washing and drying process>

[0353] Next, the solid content was filtered out, washed with deionized water, and dried to obtain toner particles (1) having a volume average particle size of 5.2 μm.

[0354] <Addition of external additives>

[0355] 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 aperture of 45 μm to obtain a toner (1) (toner for electrostatic latent image development). The volume average particle size of the toner (1) was 5.0 μm.

[0356] <Preparation of carrier>

[0357] After stirring 500 parts of spherical magnetite powder particles (volume average particle size 0.55 μm) with a Henschel mixer, 5 parts of a titanate coupling agent were added, the temperature was raised to 100°C, and the mixture was 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 coupling agent, 6.25 parts of 25% ammonia water, and 425 parts of water were added to a four-necked flask and stirred, and the mixture was reacted at 85°C for 120 minutes while stirring. Next, the mixture was cooled to 25°C, 500 parts of water were added, the supernatant 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.

[0358] <Mixing of toner and carrier>

[0359] The toner (1) and the carrier (CA) were placed in a V mixer at a ratio of toner (1):carrier (CA) = 5:95 (mass ratio) and stirred for 20 minutes to obtain a developer (1) (electrostatic latent image developer).

[0360] (Example 2)

[0361] In the welding process, the stirring Reynolds number is set to 1.0×10 6 Toner particles were prepared in the same manner as in Example 1 except that the stirring was changed to .

[0362] (Example 3)

[0363] In the welding process, the stirring Reynolds number is set to 9.0×10 5 Toner particles were prepared in the same manner as in Example 1 except that the stirring was changed to .

[0364] (Example 4)

[0365] In the welding process, the stirring Reynolds number is set to 6.0×10 4 Toner particles were prepared in the same manner as in Example 1 except that the stirring was changed to .

[0366] (Example 5)

[0367] In the welding process, the stirring Reynolds number is set to 5.5×10 4 Toner particles were prepared in the same manner as in Example 1 except that the stirring was changed to .

[0368] (Example 6)

[0369] In the welding process, the stirring Reynolds number is set to 5.0×10 4 Toner particles were prepared in the same manner as in Example 1 except that the stirring was changed to .

[0370] (Example 7)

[0371] Toner particles were prepared in the same manner as in Example 1, except that the amount of the crystalline polyester resin particle dispersion (C) was changed to 8000 parts in the step of forming aggregated particles.

[0372] (Example 8)

[0373] Toner particles were prepared in the same manner as in Example 1 except that the amount of the crystalline polyester resin particle dispersion (C) was changed to 1500 parts in the step of forming aggregated particles.

[0374] (Example 9)

[0375] In the step of forming aggregated particles, the crystalline polyester resin particle dispersion (C) was changed to 5340 parts. In the fusion step, the temperature of the first heating was changed to 84° C. Toner particles were prepared in the same manner as in Example 1 except for the above.

[0376] (Example 10)

[0377] In the step of forming aggregated particles, the amount of the crystalline polyester resin particle dispersion (C) was changed to 2000 parts. In the fusion step, the temperature of the first heating was changed to 87° C. Toner particles were prepared in the same manner as in Example 1 except for the above.

[0378] (Example 11)

[0379] In the fusing step, toner particles were produced in the same manner as in Example 1 except that the temperature of the first heating was changed to 75° C.

[0380] (Example 12)

[0381] In the fusing step, toner particles were produced in the same manner as in Example 1 except that the temperature of the first heating was changed to 78° C.

[0382] (Example 13)

[0383] In the fusion step, toner particles were produced in the same manner as in Example 1 except that the temperature of the first heating was changed to 88° C.

[0384] (Example 14)

[0385] In the fusion step, toner particles were produced in the same manner as in Example 1 except that the temperature of the first heating was changed to 92° C.

[0386] (Example 15)

[0387] In the fusion step, toner particles were produced in the same manner as in Example 1 except that the temperature of the first heating was changed to 95° C.

[0388] (Example 16)

[0389] Toner particles were produced in the same manner as in Example 1, except that the stirring blades provided in the circulation reaction tank were changed to four propeller blades in the step of forming aggregated particles.

[0390] (Comparative Example 1)

[0391] In the welding process, the stirring Reynolds number is set to 1.0×10 7 Toner particles were prepared in the same manner as in Example 1 except that the stirring was changed to .

[0392] (Comparative Example 2)

[0393] In the welding process, the stirring Reynolds number is set to 3.0×10 4 Toner particles were prepared in the same manner as in Example 1 except that the stirring was changed to .

[0394] <Method for measuring viscosity of adhesive resin using a flow tester>

[0395] The viscosity of the binder resin was measured using a flow tester CFT-500 (manufactured by Shimadzu Corporation) with the diameter of the fine hole of the mold set to 1.0 mm and the pressure load set to 10 kgf / cm 2 , set the heating rate to 7°C / min, and the starting temperature to 60°C, and find the temperature that will cause 1cm 3 The viscosity of the sample when it is melted and flows out (melt viscosity).

[0396] <Image unevenness on water-containing paper under high temperature and high humidity conditions (image unevenness suppression)>

[0397] The developer of each example was placed in the developing device of the modified image forming device ApeosPortIV C5575 (manufactured by FUJIFILM Business Innovation Corp.). An image of a rectangular mark of 10,000 sheets was outputted in such a manner that the image density became 20% using embossed paper (manufactured by Tokushu Tokai Paper Co., Ltd., LEZAC66, 203 gsm) placed under an environment of 28°C and 85% RH for one day and humidified. A spectrometer (938 Spectrod ensitometer, X-Rite) was used to measure the color reproducibility (L * 、a * 、b * ) Calculate L at a total of 9 locations * Value, a * Value and b * The color difference ΔE was calculated by the following equation:

[0398] ΔE={(L * -L * average value) 2 +(a * -a * average value) 2 +(b * -b * average value) 2 ) 0.5

[0399] The largest value among the nine points is defined as ΔE. max , and were evaluated according to the following grades. As the evaluation results, for example, G1 to G3 are preferred.

[0400] G1: ΔE max 0 or more and less than 0.5

[0401] G2: ΔE max 0.5 or more and less than 2

[0402] G3: ΔE max 2 or more and less than 3.5

[0403] G4: ΔE max 3.5 or more and less than 5

[0404] G5: ΔE max 5 or more

[0405] <Method for measuring fixing temperature (low temperature fixing property)>

[0406] A solid black image was outputted using the same paper under the same equipment and environmental conditions as the evaluation of image unevenness on water-containing paper, with the set temperature set at 160°C. After the entire fixing device was cooled to room temperature, the temperature was increased by 5°C at a time from the set temperature of 160°C to 210°C and output was performed.

[0407] A load of 3 kgf was applied to the image surface of each obtained fixed image and the image was folded inward. The degree of peeling of the image at the folding part was observed, and the width of the paper appearing at the folding part as a result of image peeling was measured. The fixing temperature at which the width became less than 0.5 mm was taken as MFT (minimum fixing temperature, ° C). The lower the minimum fixing temperature, the better the low-temperature fixing property was, and the evaluation was performed according to the following grades. As the evaluation results, for example, G1 to G3 were preferred.

[0408] G1: MFT is below 170℃

[0409] G2: MFT is 175°C or higher and 180°C or lower

[0410] G3: MFT is 185°C or higher and 190°C or lower

[0411] G4: MFT is above 195℃ and below 200℃

[0412] G5: MFT is above 205℃

[0413] [Table 1]

[0414]

[0415] In addition, the proportion of the crystalline polyester resin in Table 1 is the proportion 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 agglomerated particles at the temperature after the temperature is increased in the welding process when the welding process is started.

[0416] From the above results, it is understood that the toner for developing electrostatic latent images in this example can be obtained with excellent image unevenness suppression performance compared with the comparative example.

[0417] (1) A method for producing a toner for electrostatic latent image development, comprising the steps of: a step of aggregating particles containing binder resin particles in a dispersion to form aggregated particles; and a step of heating the aggregated particles to fuse them, wherein the dispersion is stirred at a stirring Reynolds number of 5.0×10 4 Above and 1.0×10 6 the following.

[0418] (2) A method for producing a toner for electrostatic latent image development according to (1), wherein, in the welding step, when the viscosity of the binder resin of the binder resin particles is set to η and the temperature after the heating is set to T, 1,000 Pa·s≤η(T)≤4,500 Pa·s is satisfied.

[0419] (3) A method for producing a toner for electrostatic latent image development according to (2), wherein, in the welding step, when the viscosity of the binder resin of the binder resin particles is set to η and the temperature after the heating is set to T, 2,000 Pa·s≤η(T)≤4,500 Pa·s is satisfied.

[0420] (4) The method for producing a toner for developing an electrostatic latent image according to any one of (1) to (3), wherein a 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.

[0421] (5) The method for producing a toner for developing an electrostatic latent image according to (4), wherein a 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.

[0422] (6) The method for producing a toner for electrostatic latent image development according to any one of (1) to (5), wherein a solid content of the dispersion in the fusion step is 8% by mass or more and 30% by mass or less.

[0423] (7) A method for producing a toner for electrostatic latent image development according to any one of (1) to (6), wherein the temperature after the temperature increase in the welding step is greater than the glass transition temperature of the binder resin and less than (the glass transition temperature of the binder resin + 40° C.).

[0424] (8) The method for producing a toner for developing an electrostatic latent image according to any one of (1) to (7), wherein the stirring Reynolds number is 6.0×10 4 Above and 9.0×10 5 the following.

[0425] (9) The method for producing a toner for developing an electrostatic latent image according to any one of (1) to (8), wherein an acidic aqueous solution is added in the fusing step.

[0426] (10) The method for producing a toner for developing an electrostatic latent image according to any one of (1) to (9), wherein a pH in the fusion step is 6 or more and 10 or less.

[0427] (11) The method for producing a toner for electrostatic latent image development according to any one of (1) to (10), wherein a stirring device having a propeller-type, anchor-type or paddle-type stirring blade and a rotating shaft is used for stirring the dispersion during the welding step.

[0428] According to the invention of (1), (9) or (11), there is provided a method for producing a toner for electrostatic latent image development, comprising the steps of: a step of aggregating particles containing binder resin particles in a dispersion to form agglomerated particles; and a step of heating the agglomerated particles to fuse them, wherein the dispersion is stirred at a stirring Reynolds number of less than 5.0×10 4 or more than 1.0×10 6 Compared with the case of , the image unevenness suppression is excellent.

[0429] According to the invention as set forth in (2), there is provided a method for producing a toner for developing an electrostatic latent image which is more excellent in suppressing image unevenness than when the η(T) is less than 1,000 Pa·s or exceeds 4,500 Pa·s.

[0430] According to the invention as set forth in (3), there is provided a method for producing a toner for developing an electrostatic latent image which is more excellent in suppressing image unevenness than when the η(T) is less than 2,000 Pa·s or exceeds 4,500 Pa·s.

[0431] According to the invention involved in (4), there is provided a method for producing a toner for electrostatic latent image development which has excellent low-temperature fixing property and better image unevenness suppression property than the case where the proportion of the crystalline polyester resin contained in the binder resin in the obtained toner particles is less than 15% by mass or exceeds 50% by mass.

[0432] According to the invention involved in (5), there is provided a method for producing a toner for electrostatic latent image development which has excellent low-temperature fixing property and better image unevenness suppression property than the case where the proportion of the crystalline polyester resin contained in the binder resin in the obtained toner particles is less than 20% by mass or exceeds 40% by mass.

[0433] According to the invention described in (6), there is provided a method for producing a toner for electrostatic latent image development having better image unevenness suppression performance than when the solid content of the dispersion in the welding step is less than 8% by mass or exceeds 30% by mass.

[0434] According to the invention involved in (7), there is provided a method for producing a toner for electrostatic latent image development which has better image unevenness suppression performance than a case where the temperature of the dispersion liquid in the welding step is lower than the glass transition temperature of the binder resin or exceeds (the glass transition temperature of the binder resin + 40°C).

[0435] According to the invention described in (8), there is provided a stirring Reynolds number less than 6.0×10 4 or more than 9.0×10 5 A method for producing a toner for developing an electrostatic latent image having better image unevenness suppression performance than that of the case of FIG.

[0436] According to the invention pertaining to (10), there is provided a method for producing a toner for developing an electrostatic latent image which is more excellent in suppressing image unevenness than when the pH in the fusing step is less than 6 or exceeds 10.

[0437] The above-mentioned embodiments of the present invention are provided for the purpose of illustration and description. In addition, the embodiments of the present invention do not fully and exhaustively include the present invention, and do not limit the present invention to the disclosed methods. Obviously, various modifications and changes are self-evident to those skilled in the art to which the present invention belongs. The present embodiment is selected and described in order to most easily understand the principles of the present invention and its application. Thus, other technicians in the art can understand the present invention through various variations optimized for specific uses assumed to be various embodiments. The scope of the present invention is defined by the above claims and their equivalents.

Claims

1. A method for producing a toner for electrostatic latent image development, comprising the following steps: a step of agglomerating particles containing binder resin particles in the dispersion to form aggregated particles; and The agglomerated particles are heated to a high temperature to be fused together. The stirring Reynolds number when stirring the dispersion in the welding step is 5.0×10 4 Above and 1.0×10 6 the following.

2. The method for producing a toner for developing an electrostatic latent image according to claim 1, wherein: In the welding step, when the viscosity of the binder resin of the binder resin particles is η and the temperature after the heating is T, 1,000 Pa·s≤η(T)≤4,500 Pa·s is satisfied.

3. The method for producing a toner for developing an electrostatic latent image according to claim 2, wherein: In the welding step, when the viscosity of the binder resin of the binder resin particles is η and the temperature after the heating is T, 2,000 Pa·s≤η(T)≤4,500 Pa·s is satisfied.

4. The method for producing a toner for developing an electrostatic latent image according to any one of claims 1 to 3, wherein: The ratio of the crystalline polyester resin contained in the binder resin in the obtained toner particles is 15 mass % or more and 50 mass % or less.

5. The method for producing a toner for developing an electrostatic latent image according to claim 4, wherein: 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.

6. The method for producing a toner for developing an electrostatic latent image according to any one of claims 1 to 5, wherein: The solid content of the dispersion in the welding step is 8 mass % or more and 30 mass % or less.

7. The method for producing a toner for developing an electrostatic latent image according to any one of claims 1 to 6, wherein: The temperature after the temperature increase in the welding step is equal to or higher than the glass transition temperature of the binder resin and equal to or lower than (glass transition temperature of the binder resin+40° C.).

8. The method for producing a toner for developing an electrostatic latent image according to any one of claims 1 to 7, wherein: The stirring Reynolds number is 6.0×10 4 Above and 9.0×10 5 the following.

9. The method for producing a toner for developing an electrostatic latent image according to any one of claims 1 to 8, wherein: An acidic aqueous solution is added in the welding step.

10. The method for producing a toner for developing an electrostatic latent image according to any one of claims 1 to 9, wherein: The pH in the welding step is 6 or more and 10 or less.

11. The method for producing a toner for developing an electrostatic latent image according to any one of claims 1 to 10, wherein: In stirring the dispersion during the welding step, a stirring device including a propeller-type, anchor-type, or paddle-type stirring blade and a rotating shaft is used.

Images