Method for producing resin particles and method for producing toner for developing electrostatic images

Abstract

To provide a method for producing resin particles by preventing the occurrence of coarse powder.SOLUTION: A method for producing resin particles includes a first step for adding, to an aqueous mother medium, a monomer-containing emulsion containing a polymerizable monomer and an aqueous medium, to polymerize the polymerizable monomer, and a second step in which, after the completion of adding the monomer-containing emulsion to the aqueous mother medium, an aqueous medium for cooling is then added to the aqueous mother medium.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing resin particles and a method for producing a toner for developing electrostatic images. [Background technology]

[0002] Patent Document 1 describes a reactor having a jacket portion on the periphery, a supply pump for supplying cooling water to the jacket portion, and a supply pipe provided with a control valve for supplying cooling water from the supply pump to the jacket portion and adjusting the amount of cooling water supplied. An initial charge liquid containing at least one selected from water, a monomer, and an emulsifier is charged into the reaction vessel, Next, the temperature of the initial charge liquid is raised to an initial heating temperature, and then an initial catalyst-containing liquid is added as necessary; Next, a monomer-containing dropping solution containing a monomer to be dropped and a catalyst dropping solution containing a catalyst to be dropped are continuously dropped into the reaction vessel, and emulsion polymerization of the monomers is carried out while adjusting the temperature inside the reaction vessel to approach a predetermined polymerization temperature, in a method for producing an aqueous emulsion polymer, When the predetermined polymerization temperature is Tp (°C), the temperature of the monomer-containing dripping liquid is Ta (°C), the initial heating temperature is Tb (°C), the temperature of the initial catalyst-containing liquid is Tc (°C), and the temperature of the catalyst dripping liquid is Td (°C), the amount of heat removed from the reaction system per 1°C (Q / T) to be removed from the reaction system to keep the polymerization temperature constant is calculated according to the following formula (6) using the amount of heat generated by the monomer (Qm) represented by the following formula (1), the amount of heat removed by the monomer-containing dripping liquid (Qa) represented by the following formula (2), the amount of heat removed by the initial charged liquid after the initial heating (Qb) represented by the following formula (3), the amount of heat removed by the initial catalyst-containing liquid (Qc) represented by the following formula (4), and the amount of heat removed by the catalyst dripping liquid (Qd) represented by the following formula (5), all of which are based on the polymerization temperature (Tp), ·Qm(kcal)=Σ(Mn×qn)···(1) ·Qa(kcal)=R1×(Tp-Ta)···(2) ·Qb(kcal)=R2×(Tp-Tb)···(3) ·Qc(kcal)=R3×(Tp-Tc)···(4) ·Qd(kcal)=R4×(Tp-Td)···(5) ·Q / T(kcal / ℃)=(Qm-Qa-Qb-Qc-Qd) / (Tp-Ta)···(6) (n represents an integer. Mn represents the amount (kg) of the nth monomer used, and qn represents the heat of polymerization (kcal / kg) of the nth monomer. R1 represents the amount (kg) of the monomer-containing dripping liquid, R2 represents the amount (kg) of the initial charge liquid, R3 represents the amount (kg) of the initial catalyst-containing liquid, and R4 represents the amount (kg) of the catalyst dripping liquid.) Next, the supply amount (W) of cooling water per predetermined time is calculated using the following formula (7): W (liters / min) = X × (Q / T) 1 / 2 / Rt (7) (Rt indicates the reaction time (min), and X indicates the coefficient.) Next, when the open time of the control valve is S1 (seconds) and the closed time of the control valve is S2 (seconds), the valve opening degree OP (%) when the control valve is open is set to a value obtained by the following formula (8), thereby maintaining the temperature in the emulsion polymerization within a range of 5% above or below the polymerization temperature Tp. ·OP(%)=(W / P)×(S1 / (S1+S2))×100...(8) (P indicates the maximum supply volume of the pump (liters / min). Also, S1>0, S2>0.)" has been proposed.

[0003] Patent Document 2 proposes "a method for producing a polymer stabilized with a protective colloid by emulsion polymerization in a reactor having an external cooling circuit equipped with a pump and a heat exchanger, characterized in that the reaction mixture present in the reactor is conveyed using a pump into a cooled static mixer-heat exchanger having a fixed internal structure, and then returned to the reactor." [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-024309 [Patent Document 2] Special Publication No. 2010-537022 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention addresses the problem of providing a method for producing resin particles that suppresses the generation of coarse powder compared to a method in which a monomer-containing emulsion containing a polymerizable monomer and an aqueous medium is added to an aqueous mother medium to polymerize the polymerizable monomer, in which no aqueous medium for cooling is added to the aqueous mother medium after the addition of the monomer-containing emulsion to the aqueous mother medium is complete, or in which the polymerizable monomers are a styrene-based monomer and a (meth)acrylic acid-based monomer, the content of the (meth)acrylic acid-based monomer relative to the styrene-based monomer is 20% by mass or more and 60% by mass or less, and the temperature of the aqueous mother medium after the addition of the monomer-containing emulsion is maintained outside a range of ±1.5°C of the set temperature. [Means for solving the problem]

[0006] The above problems are solved by the following means: <1> a first step of adding a monomer-containing emulsion containing a polymerizable monomer and an aqueous medium to an aqueous mother medium to polymerize the polymerizable monomer; a second step of adding a cooling aqueous medium to the aqueous mother medium after the addition of the monomer-containing emulsion to the aqueous mother medium is completed; A method for producing resin particles having the formula: <2> In the second step, an aqueous cooling medium is added to the aqueous mother medium within 5 minutes after the addition of the monomer-containing emulsion to the aqueous mother medium is completed. <1> 1. A method for producing resin particles according to claim 1. <3> In the first step, a first monomer-containing emulsion containing a first polymerizable monomer as the polymerizable monomer is added to the aqueous mother medium, the first polymerizable monomer is polymerized to generate seed resin particles, and then a second monomer-containing emulsion containing a second polymerizable monomer as the polymerizable monomer is added to polymerize the second polymerizable monomer. <1> or <2> 1. A method for producing resin particles according to claim 1. <4> In the second step, when V1 is the addition rate of the cooling aqueous medium, C1 is the specific heat of the cooling aqueous medium, V2 is the addition rate of the second monomer-containing emulsion, and C2 is the specific heat of the second monomer-containing emulsion, the ratio V1C1 / V2C2 satisfies 0.5≦V1C1 / V2C2≦1.5. <3> 1. A method for producing resin particles according to claim 1. <5> In the second step, when the absolute value (|Tp-Tm|) of the difference between the set temperature Tp of the aqueous mother medium after the addition of the monomer-containing emulsion is completed and the actual temperature Tm of the aqueous mother medium is ΔT, ΔT, V1, and the amount V3 of the cooling aqueous medium to be added when the temperature of the aqueous mother medium changes by ΔT satisfy the following formulas (1) and (2): <1> ~ <4> 10. The method for producing resin particles according to any one of the above items. Formula (1): V3=V1×a×ΔT Formula (2): 5.6≦a≦7.0 <6> When the actual temperature of the aqueous mother medium at the time of completing the addition of the monomer-containing emulsion is Tm(0), the temperature of the cooling aqueous medium is Tm(0)-50°C or more and Tm(0)-30°C or less. <1> ~ <5> 10. The method for producing resin particles according to any one of the above. <7> The temperature of the cooling aqueous medium is 10°C or higher and 45°C or lower. <6> 1. A method for producing resin particles according to claim 1. <8> The temperature of the aqueous mother medium is 60°C or higher and 80°C or lower. <6> or <7> 1. A method for producing resin particles according to claim 1. <9> The polymerizable monomer is a styrene-based monomer and a (meth)acrylic acid-based monomer. <1> ~ <8> 10. The method for producing resin particles according to any one of the above. <10> The content of the (meth)acrylic acid-based monomer relative to the styrene-based monomer is 20% by mass or more and 60% by mass or less. <9> 10. The method for producing resin particles according to any one of the above. <11> The monomer-containing emulsion and the cooling aqueous medium are added to the aqueous mother medium through the same liquid transfer pipe. <1> ~ <10> 10. The method for producing resin particles according to any one of the above. <12> The tip of the liquid delivery pipe on the liquid discharge side is immersed in the aqueous mother medium. <11> 1. A method for producing resin particles according to claim 1. <13> a step of adding a monomer-containing emulsion containing a polymerizable monomer and an aqueous medium to an aqueous mother medium, and polymerizing the polymerizable monomer; the polymerizable monomers are a styrene-based monomer and a (meth)acrylic acid-based monomer, and the content of the (meth)acrylic acid-based monomer relative to the styrene-based monomer is 20% by mass or more and 60% by mass or less; a method for producing resin particles, wherein the temperature of the aqueous mother medium after the addition of the monomer-containing emulsion is maintained within a range of a set temperature ±1.5°C; <14> The aforementioned <1> ~ <13> a step of aggregating at least the resin particles in a dispersion containing the resin particles obtained by the method for producing resin particles according to any one of the above items to form aggregated particles; a step of heating the aggregated particle dispersion in which the aggregated particles are dispersed to fuse and coalesce the aggregated particles to form toner particles; A method for producing a toner for developing electrostatic images, comprising: [Effects of the Invention]

[0007] <1> According to the present invention, in a method for producing resin particles in which a monomer-containing emulsion containing a polymerizable monomer and an aqueous medium is added to an aqueous mother medium to polymerize the polymerizable monomer, the method for producing resin particles is provided, which suppresses the generation of coarse powder compared to when a cooling aqueous medium is not added to the aqueous mother medium after the addition of the monomer-containing emulsion to the aqueous mother medium is completed. <2> According to the present invention, a method for producing resin particles is provided that suppresses the generation of coarse powder in the second step compared to when an aqueous cooling medium is added to the aqueous mother medium more than 5 minutes after the addition of the monomer-containing emulsion to the aqueous mother medium is completed. <3> According to the invention, there is provided a method for producing resin particles in which the generation of coarse powder is suppressed compared to when the polymerizable monomer is added to the aqueous mother medium all at once in the first step. <4> According to the invention, when the addition rate of the cooling aqueous medium is V1, the specific heat of the cooling aqueous medium is C1, the addition rate of the second monomer-containing emulsion is V2, and the specific heat of the second monomer-containing emulsion is C2, a method for producing resin particles is provided that suppresses the generation of coarse powder compared to when 0.5>V1C1 / V2C2 or V1C1 / V2C2>1.5 is satisfied in the second step. <5> According to the invention, there is provided a method for producing resin particles in which, in the second step, when ΔT is the absolute value of the difference (|Tp-Tm|) between the set temperature Tp of the aqueous mother medium after the addition of the monomer-containing emulsion is completed and the measured temperature Tm of the aqueous mother medium, ΔT, V1, and the amount V3 of the cooling aqueous medium added when the temperature of the aqueous mother medium changes by ΔT satisfy the following formulas (1) and (2C): Formula (1): V3=V1×a×ΔT Formula (2C): 5.6>a, or a>7.0

[0008] <6> According to the present invention, when the measured temperature of the aqueous mother medium at the end of addition of the monomer-containing emulsion is Tm(0), a method for producing resin particles is provided that suppresses the generation of coarse powder compared to when the temperature of the cooling aqueous medium is less than Tm(0)-50°C or more than Tm(0)-30°C. <7> According to the present invention, a method for producing resin particles is provided that suppresses the generation of coarse powder compared to when the temperature of the cooling aqueous medium is less than 10°C or more than 45°C. <8> According to the present invention, a method for producing resin particles is provided that suppresses the generation of coarse powder compared to when the temperature of the aqueous mother medium is less than 60°C or more than 80°C. <9> According to the present invention, there is provided a method for producing styrene (meth)acrylic copolymer resin particles, which comprises adding a monomer-containing emulsion containing a polymerizable monomer and an aqueous medium to an aqueous mother medium to polymerize the polymerizable monomer, and which suppresses the generation of coarse powder compared to a case in which a cooling aqueous medium is not added to the aqueous mother medium after the addition of the monomer-containing emulsion to the aqueous mother medium is completed. <10> According to the present invention, a method for producing resin particles is provided that suppresses the generation of coarse powder compared to when the content of (meth)acrylic acid-based monomer relative to the styrene-based monomer is less than 20% by mass or more than 60% by mass.

[0009] <11> According to the present invention, a method for producing resin particles is provided that suppresses the generation of coarse powder compared to when the monomer-containing emulsion and the cooling aqueous medium are added to the aqueous mother medium from different liquid transfer pipes. <12> According to the present invention, a method for producing resin particles is provided that suppresses the generation of coarse powder compared to when the tip of the liquid delivery tube on the liquid discharge side is not immersed in the aqueous mother medium. <13> According to the invention, there is provided a method for producing resin particles, which includes a step of adding a monomer-containing emulsion containing a polymerizable monomer and an aqueous medium to an aqueous mother medium to polymerize the polymerizable monomer, wherein the polymerizable monomers are a styrene-based monomer and a (meth)acrylic acid-based monomer, and the content of the (meth)acrylic acid-based monomer relative to the styrene-based monomer is 20% by mass or more and 60% by mass or less, and which suppresses the generation of coarse powder compared to when the temperature of the aqueous mother medium after the addition of the monomer-containing emulsion is maintained outside the range of ±1.5°C of the set temperature. <14> According to the invention, in a method for producing resin particles in which a monomer-containing emulsion containing a polymerizable monomer and an aqueous medium is added to an aqueous mother medium to polymerize the polymerizable monomer, the method provides a method for producing a toner for developing electrostatic images in which the occurrence of image defects is suppressed and low-temperature fixability is improved compared to when no aqueous medium for cooling is added to the aqueous mother medium after completion of the addition of the monomer-containing emulsion to the aqueous mother medium, or when the polymerizable monomers are a styrene-based monomer and a (meth)acrylic acid-based monomer, the content of the (meth)acrylic acid-based monomer relative to the styrene-based monomer is 20% by mass or more and 60% by mass or less, and the temperature of the aqueous mother medium after the addition of the monomer-containing emulsion is maintained outside the range of a set temperature ±1.5°C. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described. These descriptions and examples are intended to illustrate the embodiment and are not intended to limit the scope of the invention. In the present specification, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range. In addition, in the present specification, the upper or lower limit of a numerical range may be replaced with a value shown in the examples. In this specification, (meth)acrylic means both acrylic and methacrylic.

[0011] Each component may contain multiple types of the corresponding substance. When referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, the amount refers to the total amount of those multiple substances present in the composition, unless otherwise specified.

[0012] <Method of manufacturing resin particles> The method for producing resin particles according to the first embodiment includes a first step of adding a monomer-containing emulsion containing a polymerizable monomer and an aqueous medium to an aqueous mother medium to polymerize the polymerizable monomer, and a second step of adding a cooling aqueous medium to the aqueous mother medium after the addition of the monomer-containing emulsion to the aqueous mother medium is completed.

[0013] The method for producing resin particles according to the first embodiment is a method for producing resin particles that suppresses the generation of coarse powder due to the above-described configuration. The reason for this is presumed to be as follows.

[0014] In a method for producing resin particles, which comprises adding a monomer-containing emulsion containing a polymerizable monomer and an aqueous medium to an aqueous mother medium to polymerize the polymerizable monomer, it is preferable to reduce the temperature fluctuation of the reaction solution (a solution containing an aqueous mother medium and a monomer-containing emulsion) in order to suppress the generation of coarse particles. In the method for producing resin particles as described above, the temperature of the reaction solution is controlled by a reaction vessel equipped with a temperature control function, or by adding a monomer-containing emulsion whose temperature is lower than that of the reaction solution, thereby reducing the temperature fluctuation. However, polymerization of the monomer may continue even after the addition of the monomer-containing emulsion is completed. As the polymerization of the monomer progresses, reaction heat is generated, which tends to increase the temperature of the reaction solution, resulting in large fluctuations in the temperature of the reaction solution. As a result, the generation of coarse powder may not be sufficiently suppressed.

[0015] The method for producing resin particles according to the first embodiment includes a first step of adding a monomer-containing emulsion containing a polymerizable monomer and an aqueous medium to an aqueous mother medium and polymerizing the polymerizable monomer, and a second step of adding a cooling aqueous medium to the aqueous mother medium after the addition of the monomer-containing emulsion to the aqueous mother medium is completed. By including the second step, even if the polymerization of the monomers has progressed after the addition of the monomer-containing emulsion is completed, the temperature fluctuation of the reaction solution can be suppressed by adding the aqueous cooling medium, and therefore the generation of coarse particles can be easily suppressed.

[0016] From the above, it is presumed that the method for producing resin particles according to the first embodiment is a method for producing resin particles that suppresses the generation of coarse powder.

[0017] The method for producing resin particles according to the second embodiment includes a step of adding a monomer-containing emulsion containing a polymerizable monomer and an aqueous medium to an aqueous mother medium, and polymerizing the polymerizable monomer. The polymerizable monomers are a styrene-based monomer and a (meth)acrylic acid-based monomer, and the content of the (meth)acrylic acid-based monomer relative to the styrene-based monomer is 20% by mass or more and 60% by mass or less. After the addition of the monomer-containing emulsion, the temperature of the aqueous mother medium is maintained within a range of ±1.5°C of the set temperature.

[0018] The method for producing resin particles according to the second embodiment is a method for producing resin particles that suppresses the generation of coarse powder due to the above-mentioned configuration. The reason for this is presumed to be as follows.

[0019] In a method for producing resin particles, which includes adding a monomer-containing emulsion containing a polymerizable monomer and an aqueous medium to an aqueous mother medium to polymerize the polymerizable monomer, if the polymerizable monomer is a styrene-based monomer and a (meth)acrylic acid-based monomer, and the content of the (meth)acrylic acid-based monomer relative to the styrene-based monomer is 20% by mass or more and 60% by mass or less, polymerization of the monomers tends to continue even after the addition of the monomer-containing emulsion is completed. As a result, reaction heat is generated, which tends to increase the temperature of the reaction solution, resulting in large temperature fluctuations. As a result, the generation of coarse powder may not be sufficiently suppressed.

[0020] On the other hand, the method for producing resin particles according to the second embodiment includes a step of adding a monomer-containing emulsion containing a polymerizable monomer and an aqueous medium to an aqueous mother medium to polymerize the polymerizable monomer, and when the polymerizable monomers are a styrene-based monomer and a (meth)acrylic acid-based monomer and the content of the (meth)acrylic acid-based monomer relative to the styrene-based monomer is 20% by mass or more and 60% by mass or less, the temperature of the aqueous mother medium after the addition of the monomer-containing emulsion is maintained within a range of ±1.5°C of the set temperature. By keeping the temperature of the aqueous mother medium after the addition of the monomer-containing emulsion within the above range, fluctuations in the temperature of the reaction solution are suppressed even if polymerization of the monomers proceeds after the addition of the monomer-containing emulsion is completed, and therefore, the generation of coarse particles is more likely to be suppressed.

[0021] From the above, it is presumed that the method for producing resin particles according to the second embodiment is a method for producing resin particles that suppresses the generation of coarse powder.

[0022] Hereinafter, a method for producing resin particles corresponding to either the method for producing resin particles according to the first or second embodiment will be described in detail, however, an example of the method for producing resin particles of the present invention may be any method for producing resin particles corresponding to either the method for producing resin particles according to the first or second embodiment.

[0023] (1st step) The first step is a step of adding a monomer-containing emulsion containing a polymerizable monomer and an aqueous medium to an aqueous mother medium to polymerize the polymerizable monomer.

[0024] The first step is carried out, for example, using a reaction apparatus capable of controlling the temperature. The first step may be, for example, a step of adding a monomer-containing emulsion to an aqueous mother medium contained in a reaction apparatus, and then polymerizing the polymerizable monomer contained in the reaction solution (a solution containing the aqueous mother medium and the monomer-containing emulsion).

[0025] When adding the monomer-containing emulsion to the aqueous mother medium, the method for adding the monomer emulsion is not particularly limited. However, from the viewpoint of minimizing fluctuations in the temperature of the reaction solution, it is preferable to add the monomer emulsion using a liquid transfer pipe provided in the reaction apparatus.

[0026] The temperature conditions of the reaction solution when polymerizing the polymerizable monomer are preferably selected appropriately depending on the types of polymerizable monomer and polymerization initiator used. The temperature condition of the reaction solution when polymerizing the polymerizable monomers is preferably 60°C or higher and 80°C or lower, for example, when a styrene-based monomer and a (meth)acrylic acid-based monomer are used as the polymerizable monomers and ammonium persulfate is used as the polymerization initiator.

[0027] When the monomer-containing emulsion is added to the aqueous mother medium, the temperature of the aqueous mother medium is preferably 60°C or higher and 80°C or lower, more preferably 62°C or higher and 75°C or lower, and even more preferably 64°C or higher and 70°C or lower.

[0028] By setting the temperature of the aqueous mother medium within a range of 60°C to 80°C, the temperature conditions of the reaction solution when polymerizing the polymerizable monomer tend to be favorable. In addition, fluctuations in the temperature of the reaction solution are suppressed, and the generation of coarse particles is more likely to be suppressed.

[0029] The polymerization initiator is preferably added after the polymerizable monomer is added to the aqueous mother medium. As the polymerization initiator, for example, known radical polymerization initiators such as peroxides such as dibutyl peroxide, persulfates such as sodium persulfate, and azo compounds such as 2,2'-azobis(2,4-dimethylvaleronitrile) can be used. The amount of the radical polymerization initiator used is preferably 1 part by mass or more, more preferably 5 parts by mass or more, and preferably 20 parts by mass or less, more preferably 15 parts by mass or less, relative to 100 parts by mass of the polymerizable monomer.

[0030] The amount of the monomer-containing emulsion added is preferably 100 parts by mass or more and 300 parts by mass or less, more preferably 125 parts by mass or more and 275 parts by mass or less, and even more preferably 150 parts by mass or more and 250 parts by mass or less, relative to 100 parts by mass of the aqueous mother medium.

[0031] In the first step, it is preferable to add a first monomer-containing emulsion containing a first polymerizable monomer as a polymerizable monomer to an aqueous mother medium, polymerize the first polymerizable monomer to produce seed resin particles, and then add a second monomer-containing emulsion containing a second polymerizable monomer as a polymerizable monomer to polymerize the second polymerizable monomer.

[0032] By carrying out the first step according to the above procedure, seed resin particles are generated and resin particles are produced using the seed resin particles as nuclei, which tends to suppress the generation of coarse powder.

[0033] When the first step is carried out according to the above procedure, the polymerization initiator is preferably added after the first monomer-containing emulsion is added.

[0034] Here, the first monomer-containing emulsion containing the first polymerizable monomer and the second monomer-containing emulsion containing the second polymerizable monomer may have the same composition or different compositions. The first polymerizable monomer and the second polymerizable monomer can both be polymerizable monomers described below. Furthermore, the first monomer-containing emulsion and the second monomer-containing emulsion can both be the monomer-containing emulsions described below.

[0035] When the first monomer-containing emulsion and the second monomer-containing emulsion have the same composition, the ratio of the amounts of the first monomer-containing emulsion and the second monomer-containing emulsion added (amount of first monomer-containing emulsion added / second monomer-containing emulsion) is preferably 0.5 / 100 or more and 3.0 / 100 or less, more preferably 0.7 / 100 or more and 2.0 / 100 or less, and even more preferably 0.9 / 100 or more and 1.5 / 100 or less, by mass.

[0036] -Reaction equipment- The reactor is preferably a temperature-controllable reactor. An example of a reaction device capable of controlling the temperature is a reaction device having a heating part (so-called jacket) on the outer periphery of a reaction vessel.

[0037] The reaction tank is a tank that contains an aqueous mother medium and a monomer-containing emulsion in the first step and polymerizes the polymerizable monomers, and a tank that contains an aqueous cooling medium in the second step and produces resin particles.

[0038] The heating section heats the vessel wall of the reaction vessel by flowing a heating fluid therein. The heating section is provided, for example, from the bottom to the side of the reaction vessel. The configuration of the heating section is not particularly limited as long as it heats the vessel wall of the reaction vessel until the contents of the reaction vessel reach the target temperature, and any known configuration may be used. The heating fluid introduced into the heating section is preferably, for example, steam, heated water, or the like.

[0039] The reaction apparatus preferably has a stirring blade in the reaction vessel. The shape of the stirring blade is not particularly limited as long as it is capable of stirring the contents of the reaction vessel, and well-known stirring blades may be used. The shape of the stirring blade is not particularly limited, but examples thereof include paddle blades, propeller blades, turbine blades, and the like.

[0040] The reaction apparatus preferably has a liquid transfer pipe. The liquid transfer pipe is used to transfer a fluid from the outside of the reactor into the reaction tank of the reactor. The shape of the liquid transfer tube is not particularly limited, and may be straight, curved, or the like.

[0041] The reactor preferably has a thermometer. Any known thermometer can be used as long as it can measure the temperature of the contents contained in the reaction vessel. The thermometer is preferably a contact type thermometer, for example, a thermocouple.

[0042] The compositions of the aqueous mother medium and the monomer-containing emulsion will be described below.

[0043] -Aqueous mother medium- The aqueous mother medium is an aqueous medium to which the monomer-containing emulsion is added. An aqueous medium is a medium that contains water.

[0044] ·water The water is not particularly limited, and ion-exchanged water, ultrapure water, distilled water, ultrafiltered water, etc. can be used. However, from the viewpoint of reducing the ions remaining in the resin particles, it is preferable to use at least one of ion-exchanged water and ultrapure water.

[0045] The water content in the aqueous mother medium is preferably 90% by mass or more and 100% by mass or less, and more preferably 95% by mass or more and 100% by mass or less, based on the total amount of the aqueous mother medium.

[0046] Water-soluble solvents The aqueous mother medium is mainly water, but may be mixed with a water-soluble solvent such as alcohols (e.g., methanol and ethanol), acetone, etc.

[0047] The content of the water-soluble solvent in the aqueous mother medium is preferably 0% by mass or more and 10% by mass or less, and more preferably 0% by mass or more and 5% by mass or less, based on the total amount of the aqueous mother medium.

[0048] Surfactants From the viewpoint of stably carrying out emulsion polymerization, the aqueous mother medium preferably contains a surfactant.

[0049] Examples of surfactants include anionic surfactants such as sulfate salts, sulfonates, phosphate esters, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Nonionic surfactants may be used in combination with anionic or cationic surfactants. The surfactants may be used alone or in combination of two or more.

[0050] Among these, anionic surfactants are preferred, and sulfonate-based anionic surfactants are more preferred. Examples of sulfonate-based anionic surfactants include the DOWFAX (registered trademark) series manufactured by The Dow Chemical Company.

[0051] The content of the surfactant in the aqueous mother medium is preferably 0.1% by mass or more and 5% by mass or less, more preferably 0.5% by mass or more and 2.5% by mass or less, and even more preferably 0.7% by mass or more and 1.5% by mass or less, based on the total amount of the aqueous mother medium.

[0052] -Monomer-containing emulsion- The monomer-containing emulsion contains a polymerizable monomer and an aqueous medium, and preferably contains a surfactant as needed.

[0053] Polymerizable monomers The polymerizable monomer may be a radical polymerizable monomer. The radical polymerizable monomer is a polymerizable monomer capable of undergoing radical polymerization.

[0054] The radical polymerizable monomer is preferably a monomer containing a functional group having a carbon-carbon unsaturated bond. Examples of functional groups having a carbon-carbon unsaturated bond include a (meth)acryloyl group, a vinyl group, an allyl group, and a methallyl group. From the viewpoint of improving the reactivity of radical polymerization, at least one of a (meth)acryloyl group and a vinyl group is preferred.

[0055] From the viewpoint of controlling the viscoelasticity of the resin particles, the number of functional groups having a carbon-carbon unsaturated bond contained in the radical polymerizable monomer is preferably 1 to 3, more preferably 1 to 2, and even more preferably 1, per molecule of the radical polymerizable monomer.

[0056] From the viewpoint of controlling the viscoelasticity of the resin particles, the radical polymerizable monomer preferably contains at least one of a styrene-based monomer and a (meth)acrylic acid-based monomer, and more preferably contains both a styrene-based monomer and a (meth)acrylic acid-based monomer. Here, the styrene-based monomer means a monomer having a styrene skeleton (a structure in which one of the six hydrogen atoms of benzene is substituted with a vinyl group). The (meth)acrylic acid monomer means a monomer having a (meth)acryloyl group.

[0057] Examples of styrene-based monomers include styrene, α-methylstyrene, vinylnaphthalene, alkyl-substituted styrenes having alkyl chains such as 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, and 4-ethylstyrene, halogen-substituted styrenes such as 2-chlorostyrene, 3-chlorostyrene, and 4-chlorostyrene, and fluorine-substituted styrenes such as 4-fluorostyrene and 2,5-difluorostyrene, etc. Among these, styrene and α-methylstyrene are preferred.

[0058] Examples of (meth)acrylic acid monomers include (meth)acrylic acid, n-methyl (meth)acrylate, n-ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, n-decyl (meth)acrylate, n-dodecyl (meth)acrylate, n-lauryl (meth)acrylate, n-tetradecyl (meth)acrylate, n-hexadecyl (meth)acrylate, n-octadecyl (meth)acrylate, isopropyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, isopentyl (meth)acrylate, amyl (meth)acrylate, (meth)acrylate, Examples of such acrylates include neopentyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, isooctyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, phenyl (meth)acrylate, biphenyl (meth)acrylate, diphenylethyl (meth)acrylate, t-butylphenyl (meth)acrylate, terphenyl (meth)acrylate, cyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, methoxyethyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, β-carboxyethyl (meth)acrylate, (meth)acrylonitrile, and (meth)acrylamide. Among these, n-butyl (meth)acrylate and β-carboxyethyl (meth)acrylate are preferred.

[0059] The content of the (meth)acrylic acid-based monomer relative to the styrene-based monomer is preferably 20% by mass or more and 60% by mass or less, more preferably 30% by mass or more and 57% by mass or less, and even more preferably 40% by mass or more and 55% by mass or less.

[0060] By setting the content of the (meth)acrylic acid-based monomer relative to the styrene-based monomer within the range of 20% by mass to 60% by mass, the polymerization of the polymerizable monomer tends to continue even after the addition of the monomer-containing emulsion is completed in the production of resin particles, which tends to result in large fluctuations in the temperature of the reaction solution and the generation of coarse powder. According to the method for producing resin particles of this embodiment, even if the content of the (meth)acrylic acid-based monomer relative to the styrene-based monomer is within a range of 20% by mass or more and 60% by mass or less, the temperature fluctuation of the reaction solution can be reduced, and the generation of coarse powder can be suppressed.

[0061] The total content of the styrene-based monomer and the (meth)acrylic acid-based monomer relative to the total polymerizable monomers is preferably 80% by mass or more and 100% by mass or less, more preferably 90% by mass or more and 100% by mass or less, and even more preferably 95% by mass or more and 100% by mass or less.

[0062] The content of the polymerizable monomer in the entire monomer-containing emulsion is preferably 50% by mass or more and 80% by mass or less, more preferably 55% by mass or more and 75% by mass or less, and even more preferably 60% by mass or more and 70% by mass or less.

[0063] ·Aqueous medium The aqueous medium contains water. The water contained in the aqueous medium can be the same as the water described in the aqueous mother medium.

[0064] The content of water in the aqueous medium is preferably 90% by mass or more and 100% by mass or less, and more preferably 95% by mass or more and 100% by mass or less, based on the total amount of the aqueous mother medium.

[0065] The aqueous medium is mainly water, but may be mixed with a water-soluble solvent, such as alcohols (e.g., methanol and ethanol), or acetone.

[0066] The content of the water-soluble solvent in the aqueous medium is preferably 0% by mass or more and 10% by mass or less, and more preferably 0% by mass or more and 5% by mass or less, based on the total amount of the aqueous medium.

[0067] The content of the aqueous medium relative to the entire monomer-containing emulsion is preferably 20% by mass or more and 50% by mass or less, more preferably 25% by mass or more and 45% by mass or less, and even more preferably 30% by mass or more and 40% by mass or less.

[0068] Surfactants From the viewpoint of stably carrying out emulsion polymerization, the aqueous medium preferably contains a surfactant. The water contained in the aqueous medium can be the same as the surfactant described in the aqueous mother medium.

[0069] The content of the surfactant in the entire monomer-containing emulsion is preferably 0.5% by mass or more and 10% by mass or less, more preferably 1.0% by mass or more and 5% by mass or less, and even more preferably 1.5% by mass or more and 3% by mass or less.

[0070] (2nd process) The second step is a step of adding a cooling aqueous medium to the aqueous mother medium after the monomer-containing emulsion has been added to the aqueous mother medium.

[0071] The second step is carried out, for example, using a reaction apparatus capable of controlling the temperature. Here, the same reactor as that described in the first step can be used as the reactor.

[0072] The cooling aqueous medium is an aqueous medium that is added to the aqueous mother medium (reaction solution) in order to cool the aqueous mother medium after the addition of the monomer-containing emulsion is complete. The cooling aqueous medium contains water and, if necessary, a water-soluble solvent.

[0073] ·water The water is not particularly limited, and ion-exchanged water, ultrapure water, distilled water, ultrafiltered water, etc. can be used. However, from the viewpoint of reducing the ions remaining in the resin particles, it is preferable to use at least one of ion-exchanged water and ultrapure water.

[0074] The content of water in the aqueous cooling medium is preferably 90% by mass or more and 100% by mass or less, and more preferably 95% by mass or more and 100% by mass or less, based on the total amount of the aqueous cooling medium.

[0075] The cooling aqueous medium is mainly water, but may be mixed with a water-soluble solvent such as alcohols (e.g., methanol and ethanol), acetone, etc.

[0076] The content of the water-soluble solvent in the aqueous cooling medium is preferably 0% by mass or more and 10% by mass or less, and more preferably 0% by mass or more and 5% by mass or less, based on the total amount of the aqueous cooling medium.

[0077] The method for adding the aqueous cooling medium to the aqueous mother medium is not particularly limited, but from the viewpoint of minimizing fluctuations in the temperature of the reaction solution, it is preferable to add the aqueous cooling medium using a liquid transfer pipe provided in the reaction apparatus.

[0078] In the second step, after the addition of the monomer-containing emulsion to the aqueous mother medium is completed, the cooling aqueous medium is preferably added to the aqueous mother medium within 5 minutes, more preferably within 3 minutes, and even more preferably within 1 minute.

[0079] By adding the cooling aqueous medium to the aqueous mother medium within 5 minutes after the addition of the monomer-containing emulsion to the aqueous mother medium is completed, fluctuations in the temperature of the reaction solution are further suppressed even if polymerization of the monomers proceeds after the addition of the monomer-containing emulsion is completed, and therefore the generation of coarse particles is more likely to be suppressed.

[0080] When the first step is a step of adding a first monomer-containing emulsion containing a first polymerizable monomer as a polymerizable monomer to an aqueous mother medium, polymerizing the first polymerizable monomer to produce seed resin particles, and then adding a second monomer-containing emulsion containing a second polymerizable monomer as a polymerizable monomer to polymerize the second polymerizable monomer, in the two steps, where V1 is the addition rate of the aqueous cooling medium, C1 is the specific heat of the aqueous cooling medium, V2 is the addition rate of the second monomer-containing emulsion, and C2 is the specific heat of the second monomer-containing emulsion, it is preferable that 0.5≦V1C1 / V2C2≦1.5 is satisfied, it is more preferable that 0.7≦V1C1 / V2C2≦1.3 is satisfied, and it is even more preferable that 0.9≦V1C1 / V2C2≦1.1 is satisfied.

[0081] By satisfying the relationship 0.5≦V1C1 / V2C2≦1.5, the addition of the aqueous cooling medium can achieve the same cooling effect on the reaction solution as that achieved by adding the monomer-containing emulsion. Therefore, even if the polymerization of the monomer proceeds after the addition of the monomer-containing emulsion is completed, the temperature fluctuation of the reaction solution is further suppressed. Therefore, the generation of coarse powder is more easily suppressed.

[0082] Here, the units of the addition rates V1 and V2 are "parts / min", and the units of the specific heats C1 and C2 are "J / (kg·K)". When the addition rate is changed during the addition of the cooling aqueous medium or the second monomer-containing emulsion, the addition rates V1 and V2 refer to the arithmetic mean values ​​of the addition rates for each minute from immediately after the start of the addition to the end of the addition.

[0083] The specific heat capacities C1 and C2 are measured using a calorimeter. As the calorimeter, for example, a product name DSC-60A manufactured by Shimadzu Corporation can be used. The procedure for measuring the specific heat will be described below. In differential scanning calorimetry, the temperature is raised from 0°C to 150°C at a rate of 10°C / min, and the specific heat is calculated from the ratio of the signal displacement in the DSC curve of the reference sample and the mass of the reference sample to the signal displacement in the DSC curve of the unknown sample and the mass of the unknown sample.

[0084] The rate of addition V1 of the aqueous cooling medium is preferably changed according to the amount of the aqueous mother medium (reaction solution) after the addition of the monomer-containing emulsion is completed. The ratio of the amount (parts) of the reaction solution to the addition rate V1 (amount (parts) of the reaction solution:addition rate V1) is preferably 250 or more and 1400 or less, more preferably 280 or more and 550 or less, and even more preferably 300 or more and 400 or less.

[0085] The addition rate V2 of the second monomer-containing emulsion is preferably changed depending on the amount of the aqueous mother medium after the addition of the first monomer-containing emulsion is completed. The ratio of the amount (parts) of the aqueous mother medium after the addition of the first monomer-containing emulsion is completed to the addition rate V2 (amount (parts) of the reaction solution:addition rate V2) is preferably 70 or more and 140 or less, more preferably 80 or more and 120 or less, and even more preferably 85 or more and 105 or less.

[0086] In the second step, when the absolute value of the difference (|Tp-Tm|) between the set temperature Tp of the aqueous mother medium after the addition of the monomer-containing emulsion is completed and the measured temperature Tm of the aqueous mother medium is ΔT, ΔT, V1, and the amount V3 of the cooling aqueous medium added when the temperature of the aqueous mother medium changes by ΔT preferably satisfy the following formulas (1) and (2): Formula (1): V3=V1×a×ΔT Formula (2): 5.6≦a≦7.0

[0087] Here, the unit of ΔT is "°C" and a is a dimensionless number. The unit of V3 calculated by formula (1) is originally "parts·° C. / min", but in this specification the unit of V3 is converted to "parts".

[0088] By satisfying the above formulas (1) and (2), fluctuations in the temperature of the reaction solution are further suppressed even when polymerization of the monomers progresses after the addition of the monomer-containing emulsion is completed, and therefore, the generation of coarse particles is more likely to be suppressed.

[0089] From the viewpoint of further suppressing the generation of coarse components, it is more preferable that ΔT, V1, and V3 satisfy the above formula (1) and the following formula (2-2), and it is even more preferable that they satisfy the above formula (1) and the following formula (2-3). Formula (2-2): 5.8≦a≦6.8 Formula (2-3): 6.0≦a≦6.6

[0090] Here, the set temperature Tp is a target value for the temperature of the contents contained in the reaction vessel provided in the reaction apparatus, and is set in the reaction apparatus. The actual temperature Tm is the actual temperature of the contents contained in the reaction vessel of the reactor, and is measured by a thermometer provided in the reactor.

[0091] When the measured temperature of the aqueous mother medium at the end of the addition of the monomer-containing emulsion is Tm(0), the temperature of the cooling aqueous medium is preferably Tm(0)-50°C or higher and Tm(0)-30°C or lower, more preferably Tm(0)-45°C or higher and Tm(0)-35°C or lower, and even more preferably Tm(0)-40°C or higher and Tm(0)-40°C or lower.

[0092] By setting the temperature of the cooling aqueous medium within the range of Tm(0)-50°C or more and Tm(0)-30°C or less, the temperature difference between the reaction solution and the cooling aqueous medium is not too large, and a moderate cooling effect is also achieved. Therefore, even if the polymerization of the monomer progresses after the addition of the monomer-containing emulsion is completed, the temperature fluctuation of the reaction solution is further suppressed. Therefore, the generation of coarse powder is more easily suppressed.

[0093] The temperature of the cooling aqueous medium is preferably 10°C or higher and 45°C or lower, more preferably 15°C or higher and 40°C or lower, and even more preferably 20°C or higher and 35°C or lower.

[0094] By setting the temperature of the cooling aqueous medium to 10°C or higher and 45°C or lower, the temperature difference between the reaction solution and the cooling aqueous medium is not too large, and a moderate cooling effect is also achieved. Therefore, even if the polymerization of the monomer progresses after the addition of the monomer-containing emulsion is completed, the temperature fluctuation of the reaction solution is further suppressed. Therefore, the generation of coarse powder is more easily suppressed.

[0095] (Method of adding from the liquid supply pipe) It is preferable that the monomer-containing emulsion and the cooling aqueous medium are added to the aqueous mother medium through the same liquid transfer pipe.

[0096] Adding the monomer-containing emulsion and the aqueous cooling medium from the same liquid transfer pipe tends to reduce temperature fluctuations in the reaction solution, thereby further suppressing the generation of coarse particles.

[0097] At this time, it is preferable that the tip of the liquid delivery tube on the liquid discharge side is immersed in the aqueous mother medium. By immersing the end of the liquid delivery tube on the liquid discharge side in the aqueous mother medium, the monomer-containing emulsion and the cooling aqueous medium can be easily added to the aqueous mother medium at the desired temperature. This makes it easier to minimize temperature fluctuations in the aqueous mother medium, thereby further suppressing the generation of coarse particles.

[0098] (Method of producing resin particles according to the second embodiment) The method for producing resin particles according to the second embodiment includes a step of adding a monomer-containing emulsion containing a polymerizable monomer and an aqueous medium to an aqueous mother medium, and polymerizing the polymerizable monomer. The polymerizable monomers are a styrene-based monomer and a (meth)acrylic acid-based monomer, and the content of the (meth)acrylic acid-based monomer relative to the styrene-based monomer is 20% by mass or more and 60% by mass or less. Furthermore, the temperature of the aqueous mother medium after the addition of the monomer-containing emulsion is maintained within a range of ±1.5°C of the set temperature.

[0099] The process of the second embodiment of the method for producing resin particles, in which a monomer-containing emulsion containing a polymerizable monomer and an aqueous medium is added to an aqueous mother medium to polymerize the polymerizable monomer, is the same process as the first process described above.

[0100] The polymerizable monomers are a styrene-based monomer and a (meth)acrylic acid-based monomer, and the content of the (meth)acrylic acid-based monomer relative to the styrene-based monomer is 20% by mass or more and 60% by mass or less, but from the viewpoint of suppressing the generation of coarse powder, it is more preferably 30% by mass or more and 57% by mass or less, and even more preferably 40% by mass or more and 55% by mass or less.

[0101] The temperature of the aqueous mother medium (reaction solution) after the addition of the monomer-containing emulsion is maintained within a range of ±1.5°C of the set temperature. From the viewpoint of suppressing the generation of coarse components, it is preferable to maintain it within a range of ±1.25°C of the set temperature, more preferably within a range of ±1.00°C of the set temperature, and even more preferably within a range of ±0.75°C of the set temperature.

[0102] An example of a method for maintaining the temperature of the reaction solution within a range of ±1.5°C of the set temperature is to add a cooling aqueous medium to the aqueous mother medium after the addition of the monomer-containing emulsion to the aqueous mother medium is completed.

[0103] <Resin particles> (resin) The resin particles preferably contain a resin obtained by polymerizing the above-mentioned polymerizable monomers, and from the viewpoint of achieving a preferred range of viscoelasticity, preferably contain a styrene-(meth)acrylic copolymer resin. The styrene-(meth)acrylic copolymer resin is a resin obtained by polymerizing a styrene monomer and a (meth)acrylic acid monomer. Furthermore, a resin containing a styrene-(meth)acrylic copolymer resin is referred to as a styrene-(meth)acrylic copolymer resin particle.

[0104] (particle size) The volume average particle size of the resin particles is preferably 80 nm or more and 300 nm or less, more preferably 100 nm or more and 250 nm or less, and even more preferably 120 nm or more and 200 nm or less.

[0105] The volume average particle size of the resin particles is measured using a particle size distribution obtained by measurement with a laser diffraction particle size distribution analyzer (e.g., LA-700 manufactured by Horiba, Ltd.), and the cumulative distribution for the volume of the divided particle size range (channel) is calculated from the small particle size side, and the particle size that accounts for 50% of the cumulative total of all particles is measured as the volume average particle size D50v.

[0106] (coarse powder) The resin particles preferably have a coarse powder content of 1% or less on a 200 mesh screen, more preferably 0.5% or less on a 200 mesh screen, and even more preferably 0.3% or less on a 200 mesh screen. By keeping the 200 mesh size below 1%, the amount of coarse powder contained in the resin particles is reduced.

[0107] The procedure for measuring the amount of coarse powder on a 200 mesh screen is as follows. A solution in which the resin particles to be measured are dispersed (resin particle dispersion) is passed through a 200-mesh nylon mesh (NYTAL (200 μm) manufactured by Tanaka Sanjiro Shoten Co., Ltd.). The resin particles remaining on the mesh per 100 parts of resin particle dispersion are recovered. The recovered resin particles are dried in a vacuum dryer, and then their mass is measured. The amount of coarse powder remaining on the 200-mesh mesh is calculated by dividing the mass (parts) of the recovered resin particles by (100 parts of resin particle dispersion x solid content (mass%)).

[0108] (Method of manufacturing toner for developing electrostatic images) The method for producing the toner for developing electrostatic images according to the present embodiment includes a step of forming aggregated particles by aggregating at least resin particles in a dispersion liquid containing the resin particles obtained by the above-described method for producing resin particles (aggregated particle forming step); a step of heating the aggregated particle dispersion in which the aggregated particles are dispersed to fuse and coalesce the aggregated particles to form toner particles (fusion and coalescence step).

[0109] The toner according to the exemplary embodiment can be obtained by producing toner particles and then externally adding an external additive to the toner particles, if necessary.

[0110] The toner particles may be produced by any of a dry production method (for example, a kneading and pulverization method) and a wet production method (for example, an aggregation and coalescence method, a suspension polymerization method, a dissolution and suspension method). The method for producing the toner particles is not particularly limited, and any well-known production method may be used. Among these, it is preferable to obtain toner particles by the aggregation and coalescence method.

[0111] Specifically, for example, when toner particles are produced by the aggregation and coalescence method, The toner particles are manufactured through the following steps: a step of preparing a resin particle dispersion in which resin particles to be a binder resin are dispersed, and a specific resin particle dispersion in which resin particles obtained by the resin particle manufacturing method according to this embodiment (hereinafter also referred to as specific resin particles) are dispersed (resin particle dispersion preparation step); a step of aggregating the resin particles (and other particles, if necessary) in the resin particle dispersion (in a dispersion after mixing other particle dispersions, if necessary) to form aggregated particles (aggregated particle formation step); and a step of heating the aggregated particle dispersion in which the aggregated particles are dispersed to fuse and coalesce the aggregated particles to form toner particles (fusion and coalescence step).

[0112] Each step will be described in detail below. In the following description, a method for obtaining toner particles containing a colorant and a release agent will be described, but the colorant and the release agent are used as needed. Of course, additives other than the colorant and the release agent may also be used.

[0113] -Resin particle dispersion preparation process- First, a resin particle dispersion in which resin particles serving as a binder resin are dispersed, as well as a colorant particle dispersion in which colorant particles are dispersed and a release agent particle dispersion in which release agent particles are dispersed are prepared.

[0114] Here, the resin particle dispersion liquid is prepared, for example, by dispersing resin particles in a dispersion medium using a surfactant.

[0115] Examples of the dispersion medium used in the resin particle dispersion include aqueous media. Examples of aqueous media include water such as distilled water and ion-exchanged water, alcohols, etc. These may be used alone or in combination of two or more.

[0116] Examples of surfactants include anionic surfactants such as sulfate ester salts, sulfonate salts, phosphate esters, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, anionic surfactants and cationic surfactants are particularly preferred. Nonionic surfactants may be used in combination with anionic surfactants or cationic surfactants. The surfactants may be used alone or in combination of two or more.

[0117] In the resin particle dispersion, resin particles can be dispersed in a dispersion medium by a general dispersion method such as a rotary shear homogenizer, a ball mill having a medium, a sand mill, a dyno mill, etc. Depending on the type of resin particles, the resin particles may be dispersed in the resin particle dispersion by, for example, a phase inversion emulsification method. The phase inversion emulsification method involves dissolving the resin to be dispersed in a hydrophobic organic solvent in which the resin is soluble, adding a base to the organic continuous phase (O phase) to neutralize it, and then adding an aqueous medium (W phase), thereby converting the resin from W / O to O / W (so-called phase inversion) and forming a discontinuous phase, and dispersing the resin in particulate form in the aqueous medium.

[0118] The volume average particle size of the resin particles dispersed in the resin particle dispersion is, for example, preferably from 0.01 μm to 1 μm, more preferably from 0.08 μm to 0.8 μm, and even more preferably from 0.1 μm to 0.6 μm. The volume average particle size of the resin particles is measured using a particle size distribution obtained by measurement with a laser diffraction particle size distribution analyzer (e.g., LA-700 manufactured by Horiba, Ltd.), and the cumulative distribution for the volume of the divided particle size range (channel) is subtracted from the small particle size side, and the particle size at which the cumulative 50% of all particles is measured is defined as the volume average particle size D50v. The volume average particle sizes of particles in other dispersions are also measured in the same way.

[0119] The content of resin particles contained in the resin particle dispersion is, for example, preferably from 5% by mass to 50% by mass, and more preferably from 10% by mass to 40% by mass.

[0120] Note that, for example, a colorant particle dispersion and a release agent particle dispersion are also prepared in the same manner as the resin particle dispersion. That is, the volume average particle size, dispersion medium, dispersion method, and particle content of the particles in the resin particle dispersion are the same for the colorant particles dispersed in the colorant particle dispersion and the release agent particles dispersed in the release agent particle dispersion.

[0121] The specific resin particle dispersion may be obtained by dispersing the specific resin particles obtained by the resin particle manufacturing method according to this embodiment in a dispersion medium, or, for example, an aqueous mother medium containing the specific resin particles obtained through the second step in the resin particle manufacturing method according to this embodiment may be used as the specific resin particle dispersion.

[0122] -Agglomerated particle formation process- Next, the colorant particle dispersion, the release agent particle dispersion, and the specific resin particle dispersion are mixed together with the resin particle dispersion. Then, in the mixed dispersion, the resin particles, colorant particles, release agent particles, and specific resin particles are hetero-aggregated to form aggregated particles containing the resin particles, colorant particles, release agent particles, and specific resin particles, which have a diameter close to the diameter of the target toner particles.

[0123] Specifically, for example, an aggregating agent is added to the mixed dispersion, and the pH of the mixed dispersion is adjusted to be acidic (for example, a pH of 2 or more and 5 or less), and a dispersion stabilizer is added as necessary. After that, the mixed dispersion is heated to the glass transition temperature of the resin particles (specifically, for example, a temperature of the glass transition temperature of the resin particles -30°C or more and the glass transition temperature -10°C or less), and the particles dispersed in the mixed dispersion are aggregated to form aggregated particles. In the aggregate particle formation step, for example, the above-mentioned aggregating agent may be added to the mixed dispersion at room temperature (e.g., 25°C) while stirring with a rotary shear homogenizer, the pH of the mixed dispersion may be adjusted to an acidic value (e.g., pH 2 or more and 5 or less), and a dispersion stabilizer may be added as necessary, followed by the heating.

[0124] Examples of the flocculant include a surfactant having a polarity opposite to that of the surfactant used as the dispersant added to the mixed dispersion, an inorganic metal salt, and a divalent or higher metal complex. In particular, when a metal complex is used as the flocculant, the amount of surfactant used can be reduced and the charging characteristics can be improved. If necessary, an additive that forms a complex or a similar bond with the metal ions of the flocculant may be used, and a chelating agent is preferably used as this additive.

[0125] Examples of inorganic metal salts include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate, as well as inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. The chelating agent may be a water-soluble chelating agent, such as hydroxycarboxylic acid (e.g., tartaric acid, citric acid, gluconic acid), iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), etc. The amount of the chelating agent added is, for example, preferably 0.01 parts by mass or more and 5.0 parts by mass or less, and more preferably 0.1 parts by mass or more and less than 3.0 parts by mass, per 100 parts by mass of the resin particles.

[0126] -Fusion / unification process- Next, the aggregated particle dispersion liquid in which the aggregated particles are dispersed is heated, for example, to a temperature equal to or higher than the glass transition temperature of the resin particles (for example, a temperature 10 to 30°C higher than the glass transition temperature of the resin particles), to fuse and coalesce the aggregated particles and form toner particles.

[0127] Through the above steps, toner particles are obtained. After obtaining an aggregated particle dispersion in which aggregated particles are dispersed, the toner particles may be produced through the following steps: a step of further mixing the aggregated particle dispersion with a resin particle dispersion in which resin particles are dispersed, and aggregating the aggregated particles so that further resin particles adhere to the surfaces of the aggregated particles to form second aggregated particles; and a step of heating the second aggregated particle dispersion in which the second aggregated particles are dispersed to fuse and coalesce the second aggregated particles to form toner particles having a core / shell structure.

[0128] After the fusion and coalescence process, the toner particles formed in the solution are subjected to a known washing process, a solid-liquid separation process, and a drying process to obtain dry toner particles. In the washing step, it is preferable to carry out sufficient replacement washing with ion-exchanged water from the viewpoint of electrostatic chargeability. Furthermore, the solid-liquid separation step is not particularly limited, but from the viewpoint of productivity, it is preferable to carry out suction filtration, pressure filtration, etc. Furthermore, in the drying step, there is no particular limitation on the method, but from the viewpoint of productivity, it is preferable to carry out freeze drying, flash drying, fluidized drying, vibration-type fluidized drying, etc.

[0129] The toner according to this embodiment is produced by, for example, adding an external additive to the obtained dry toner particles and mixing them. The mixing can be carried out using, for example, a V blender, a Henschel mixer, a Loedige mixer, or the like. Furthermore, if necessary, coarse particles may be removed from the toner using a vibrating sieve, an air sieve, or the like.

[0130] <Electrostatic image developer> The electrostatic image developer according to this embodiment contains at least the toner according to this embodiment. The electrostatic image developer according to this embodiment may be a one-component developer containing only the toner according to this embodiment, or may be a two-component developer containing the toner mixed with a carrier.

[0131] The carrier is not particularly limited, and examples thereof include known carriers, such as coated carriers in which the surface of a core material made of magnetic powder is coated with a coating resin, magnetic powder dispersion carriers in which magnetic powder is dispersed and blended in a matrix resin, and resin-impregnated carriers in which porous magnetic powder is impregnated with a resin. The magnetic powder dispersion type carrier and the resin impregnated type carrier may be a carrier in which the constituent particles of the carrier are used as a core material and are coated with a coating resin.

[0132] Examples of magnetic powder include magnetic metals such as iron, nickel, and cobalt, and magnetic oxides such as ferrite and magnetite.

[0133] Examples of coating resins and matrix resins include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic acid ester copolymer, straight silicone resins containing organosiloxane bonds or modified products thereof, fluororesins, polyesters, polycarbonates, phenolic resins, and epoxy resins. The coating resin and the matrix resin may contain other additives such as conductive particles. Examples of 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.

[0134] Here, the method of coating the surface of the core material with a coating resin includes a method of coating with a solution for forming a coating layer in which the coating resin and, if necessary, various additives are dissolved in an appropriate solvent. The solvent is not particularly limited and may be selected taking into consideration the coating resin to be used, its applicability, etc. Specific resin coating methods include an immersion method in which the core material is immersed in a solution for forming a coating layer, a spray method in which the solution for forming a coating layer is sprayed onto the surface of the core material, a fluidized bed method in which the solution for forming a coating layer is sprayed onto the core material while it is suspended in flowing air, and a kneader coater method in which the core material of the carrier and the solution for forming a coating layer are mixed in a kneader coater and the solvent is removed.

[0135] In the two-component developer, the mixing ratio (mass ratio) of toner to carrier is preferably toner:carrier=1:100 to 30:100, and more preferably 3:100 to 20:100.

[0136] <Toner for developing electrostatic images> The toner for developing electrostatic images (hereinafter also referred to as "toner") according to this embodiment has toner particles containing a binder resin, a release agent, and resin particles.

[0137] (toner particles) The toner particles contain a binder resin, a release agent, and specific resin particles, and may also contain a colorant and other additives as required.

[0138] -Binder resin- Examples of binder resins include homopolymers of monomers such as styrenes (e.g., styrene, parachlorostyrene, α-methylstyrene, etc.), (meth)acrylic acid esters (e.g., methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (e.g., acrylonitrile, methacrylonitrile, etc.), vinyl ethers (e.g., vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), and olefins (e.g., ethylene, propylene, butadiene, etc.), and vinyl resins made of copolymers of two or more of these monomers. Examples of the binder resin include non-vinyl resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and modified rosin, mixtures of these with the vinyl resins, and graft polymers obtained by polymerizing vinyl monomers in the presence of these. These binder resins may be used alone or in combination of two or more. The binder resin preferably contains a polyester resin.

[0139] -Mold release agent- Examples of release agents include hydrocarbon waxes, natural waxes such as carnauba wax, rice wax, and candelilla wax, synthetic or mineral / petroleum waxes such as montan wax, and ester waxes such as fatty acid esters and montanic acid esters, but are not limited thereto.

[0140] The melting temperature of the release agent is preferably 50°C or higher and 110°C or lower, and more preferably 60°C or higher and 100°C or lower. The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) by using the "melting peak temperature" as described in the method for determining the melting temperature in JIS K 7121-1987 "Method for measuring transition temperatures of plastics."

[0141] The content of the release agent is, for example, preferably 1% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less, based on the total mass of the toner particles.

[0142] -Specific resin particles- The specific resin particles used are those produced according to the method described above. The content of the specific resin particles is, for example, preferably 1% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less, based on the total mass of the toner particles.

[0143] -Other additives- Examples of other additives include well-known additives such as magnetic materials, charge control agents, inorganic powders, etc. These additives are contained in the toner particles as internal additives.

[0144] -Characteristics of toner particles, etc.- The toner particles may be toner particles of a single layer structure, or may be toner particles of a so-called core-shell structure composed of a core part (core particle) and a coating layer (shell layer) that coats the core part. Here, the toner particles having a core-shell structure may be composed of, for example, a core containing a binder resin and, if necessary, other additives such as a colorant and a release agent, and a coating layer containing the binder resin.

[0145] The volume average particle size (D50v) of the toner particles is preferably 2 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less.

[0146] The various average particle sizes and particle size distribution indices of the toner particles are measured using a Coulter Multisizer II (manufactured by Beckman Coulter), and the electrolyte is measured using an ISOTON-II (manufactured by Beckman Coulter). For the measurement, 0.5 mg to 50 mg of the sample to be measured is added to 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzene sulfonate) as a dispersant, and this is then added to 100 ml to 150 ml of the electrolyte. The electrolyte solution containing the suspended sample is dispersed for 1 minute using an ultrasonic disperser, and the particle size distribution of particles with a particle size range of 2 μm to 60 μm is measured using a Coulter Multisizer II with an aperture diameter of 100 μm. The number of particles sampled is 50,000. Based on the particle size distribution measured, cumulative distributions of volume and number are drawn for each divided particle size range (channel) from the smallest diameter side, and the particle size at 16% of the cumulative total is defined as the volume particle size D16v, the number particle size D16p, the particle size at 50% of the cumulative total as the volume average particle size D50v, the cumulative number average particle size D50p, and the particle size at 84% of the cumulative total as the volume particle size D84v and the number particle size D84p. Using these, the volume size distribution index (GSDv) is calculated as (D84v / D16v)1 / 2, and the number size distribution index (GSDp) is calculated as (D84p / D16p)1 / 2.

[0147] The average circularity of the toner particles is preferably 0.94 or more and 1.00 or less, and more preferably 0.95 or more and 0.98 or less.

[0148] The average circularity of toner particles is calculated by (circular equivalent perimeter) / (perimeter) [(perimeter of a circle having the same projected area as the particle image) / (perimeter of the particle projected image)]. Specifically, this value is measured by the following method. First, the toner particles to be measured are sucked and collected, forming a flat flow, and a still image of the particles is captured by instantaneously activating a strobe light, and the particle image is analyzed using a flow-type particle image analyzer (FPIA-3000 manufactured by Sysmex Corporation).The number of samples to be sampled when calculating the average circularity is 3,500. When the toner contains external additives, the toner (developer) to be measured is dispersed in water containing a surfactant, and then ultrasonic treatment is performed to obtain toner particles from which the external additives have been removed.

[0149] (external additives) Examples of external additives include inorganic particles such as SiO2, TiO2, Al2O3, CuO, ZnO, SnO2, CeO2, Fe2O3, MgO, BaO, CaO, KO, Na2O, ZrO2, CaO·SiO2, KO·(TiO2)n, Al2O3·2SiO2, CaCO3, MgCO3, BaSO4, and MgSO4.

[0150] The surfaces of inorganic particles as external additives are preferably subjected to a hydrophobic treatment. The hydrophobic treatment is carried out, for example, by immersing the inorganic particles in a hydrophobic treatment agent. The hydrophobic treatment agent is not particularly limited, and examples thereof include silane coupling agents, silicone oils, titanate coupling agents, and aluminum coupling agents. These may be used alone or in combination of two or more. The amount of the hydrophobic treatment agent is usually, for example, 1 part by mass or more and 10 parts by mass or less per 100 parts by mass of the inorganic particles.

[0151] Examples of external additives include resin particles (resin particles such as polystyrene, polymethyl methacrylate (PMMA), and melamine resin), cleaning agents (for example, metal salts of higher fatty acids such as zinc stearate, and particles of fluorine-based polymers).

[0152] The amount of the external additive added is, for example, preferably 0.01% by mass or more and 5% by mass or less, and more preferably 0.01% by mass or more and 2.0% by mass or less, based on the toner particles. [Example]

[0153] Examples will be described below, but the present invention is not limited to these examples. In the following description, unless otherwise specified, all "parts" and "%" are by mass.

[0154] Example 1 (Preparation of specific resin particle dispersion 1) -1st process- An aqueous mother medium was prepared by adding 2800 parts of ion-exchanged water and 23 parts of Dowfax 2A1 (a sulfonate-based anionic surfactant manufactured by The Dow Chemical Company) to a reaction vessel of a reactor equipped with a jacket, stirring blades, a liquid transfer pipe, and a thermometer, with the tip of the liquid transfer pipe on the liquid discharge side immersed in the aqueous mother medium. The aqueous mother medium was stirred at 50 rpm, and the temperature was raised to 65° C. In addition, in an emulsification tank (emulsification apparatus having a stirring blade) separate from the reaction apparatus, a polymerizable monomer (a mixture of 1800 parts of styrene and 1800 parts of n-butyl acrylate), 1700 parts of ion-exchanged water, and 90 parts of Dowfax 2A1 were stirred and mixed at 100 rpm at room temperature (25° C.) for 60 minutes to prepare a monomer-containing emulsion. Next, 60 parts of the first monomer-containing emulsion were removed from the monomer-containing emulsion, and the first monomer-containing emulsion was added to the reaction vessel using a pump over 2 minutes. Five minutes after the addition of the first monomer-containing emulsion, an aqueous polymerization initiator solution prepared by dissolving 15 parts of ammonium persulfate in 130 parts of ion-exchanged water was added to the reaction vessel over 10 minutes using the injection tube. The solution in the reaction vessel was stirred for 30 minutes to produce seed resin particles. Next, the remaining monomer-containing emulsion (second monomer-containing emulsion) was added to the reaction vessel using the liquid transfer tube at an addition rate V2 of 30 parts / min.

[0155] -Second process- Immediately after the entire monomer-containing emulsion was added, 1,500 parts of ion-exchanged water (aqueous cooling medium) was added dropwise to the reaction vessel using a liquid transfer tube at a rate of 19.5 parts / min. The actual temperature Tm of the aqueous mother medium (hereinafter also referred to as the internal temperature) was monitored every minute, and the addition rate V1 of the ion-exchanged water was changed so as to satisfy equation (1): V3 = V1 × a × ΔT and equation (2): 5.6≦a≦7.0. The set temperature Tp of the aqueous mother medium was set to 65°C. After the addition of the ion-exchanged water was completed, the solution in the reaction vessel was post-heated at 65°C for 180 minutes to complete the reaction and then cooled. After cooling, ion-exchanged water was added to adjust the solids concentration to 20%, yielding specific resin particle dispersion 1. Here, the above series of operations were carried out under a nitrogen atmosphere by passing a nitrogen stream through the reaction vessel.

[0156] (Toner and developer production) <Preparation of Polyester Resin Particle Dispersion> A reactor equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet tube was charged with 80 moles of polyoxypropylene(2,2)-2,2-bis(4-hydroxyphenyl)propane, 10 moles of ethylene glycol, 10 moles of cyclohexanediol, 80 moles of terephthalic acid, 10 moles of isophthalic acid, and 10 moles of n-dodecenylsuccinic acid, and the atmosphere in the reactor was purged with dry nitrogen gas. Then, 0.25 parts by mass of titanium tetrabutoxide was added as a catalyst per 100 parts by mass of the monomer components. After stirring and reacting for 3 hours at 170°C under a nitrogen gas stream, the temperature was further increased to 210°C over 1 hour, the pressure in the reactor was reduced to 3 kPa, and the reaction was continued with stirring under reduced pressure for 13 hours to obtain a polyester resin. Next, 200 parts by weight of polyester resin, 100 parts by weight of methyl ethyl ketone, and 70 parts by weight of isopropyl alcohol were placed in a jacketed 3-liter reactor (Tokyo Rikakikai Co., Ltd.: BJ-30N) equipped with a condenser, thermometer, water dripper, and anchor blade. The mixture was stirred and mixed at 100 rpm while maintaining the temperature at 70°C in a water-circulating thermostatic bath to dissolve the resin. The stirring speed was then increased to 150 rpm, the water-circulating thermostatic bath was set to 66°C, and 10 parts of 10% aqueous ammonia (reagent) was added over 10 minutes. A total of 600 parts by weight of ion-exchanged water maintained at 66°C was then added dropwise at a rate of 5 parts by weight / min to induce phase inversion, yielding an emulsion. 600 parts of the resulting emulsion and 525 parts by weight of ion-exchanged water were placed in a 2-liter eggplant flask and placed in an evaporator (Tokyo Rikakikai Co., Ltd.) equipped with a vacuum control unit via a trap bulb. While rotating the recovery flask, the flask was heated in a hot water bath at 60°C, and the pressure was reduced to 7 kPa while taking care to prevent bumping, and the solvent was removed. When the amount of recovered solvent reached 825 parts, the pressure was returned to normal, and the recovery flask was cooled with water to obtain a dispersion. Ion-exchanged water was added to obtain a polyester resin particle dispersion with a solids concentration of 20% by mass.

[0157] <Preparation of Crystalline Polyester Resin Particle Dispersion> 1,10-decanedicarboxylic acid: 260 parts 1,6-Hexanediol: 167 parts Dibutyltin oxide (catalyst): 0.3 parts The above materials were placed in a heated and dried three-neck flask. The air in the flask was replaced with nitrogen gas to create an inert atmosphere, and the mixture was stirred and refluxed at 180°C for 5 hours using mechanical stirring. The temperature was then gradually increased to 230°C under reduced pressure and stirred for 2 hours. When the mixture reached a viscous state, it was air-cooled to terminate the reaction. This resulted in a crystalline polyester resin with a weight-average molecular weight of 12,600 and a melting temperature of 73°C. 90 parts of the crystalline polyester resin, 1.8 parts of anionic surfactant (TaycaPower, manufactured by Tayca Corporation), and 210 parts of ion-exchanged water were mixed, heated to 120°C, and dispersed using a homogenizer (IKA Ultra-Turrax T50). This was followed by a dispersion process using a pressure-discharge Gaulin homogenizer for 1 hour, resulting in a resin particle dispersion containing resin particles with a volume average particle size of 160 nm. Ion-exchanged water was added to this resin particle dispersion to adjust the solids content to 20%, yielding a crystalline polyester resin particle dispersion.

[0158] <Preparation of release agent dispersion> Paraffin wax (manufactured by Nippon Seiro Co., Ltd., FNP92, endothermic peak onset 81°C): 45 parts Anionic surfactant (Dai-ichi Kogyo Seiyaku Co., Ltd., Neogen RK): 5 parts Ion-exchanged water: 200 parts The above ingredients were mixed and heated to 95°C, and dispersed using a homogenizer (Ultra Turrax T50, manufactured by IKA). After that, a dispersion treatment was carried out using a Manton-Gaulin high-pressure homogenizer (Gaulin), and a release agent dispersion 1 (solid content concentration: 20%) was prepared by dispersing the release agent. The volume average particle size of the release agent particles was 0.19 μm.

[0159] <Preparation of Colorant Dispersion> Cyan pigment (Dainichi Seikagaku Co., Ltd., Pigment Blue 15:3 (copper phthalocyanine)): 98 parts Anionic surfactant (Dai-ichi Kogyo Seiyaku Co., Ltd., Neogen R): 2 parts Ion-exchanged water: 400 parts The above ingredients were mixed and dissolved, and dispersed for 10 minutes using a homogenizer (IKA Ultra Turrax), to obtain a colorant dispersion with a median particle size of 0.16 μm and a solid content of 20%.

[0160] <Creating the carrier> 100 parts of ferrite particles (manufactured by Powder Tech Co., Ltd., average particle size 50 μm) and 1.5 parts of polymethyl methacrylate resin (manufactured by Mitsubishi Rayon Co., Ltd., weight average molecular weight 95,000, proportion of components with a weight average molecular weight of 10,000 or less is 5%) were placed in a pressure kneader together with 500 parts of toluene, stirred and mixed at room temperature for 15 minutes, then heated to 70°C while mixing under reduced pressure to distill off the toluene, then cooled and classified using a 105 μm sieve to obtain a resin-coated ferrite carrier.

[0161] <Toner Production> (Preparation of Toner Particles (1)) Polyester resin particle dispersion: 100 parts by weight Crystalline polyester resin particle dispersion: 20 parts by weight ·Specified resin particle dispersion liquid 1:40 parts by mass Colorant particle dispersion: 10 parts by weight Release agent particle dispersion: 9 parts by weight Anionic surfactant (Tayca Power BN2060, manufactured by Tayca Corporation): 1 part by mass Ion-exchanged water: 200 parts by weight The above raw materials were placed in a 2 L cylindrical stainless steel container 1, and 3 parts of a 0.3 M aqueous nitric acid solution was added to adjust the pH to 3.0. Next, 50 parts of a 10% aqueous solution of aluminum sulfate was added dropwise as a flocculant while applying shear force at 6,000 rpm using an Ultraturrax (manufactured by IKA Japan), and the mixture was stirred for 5 minutes. The raw material mixture was heated to 45°C using a mantle heater and held for 30 minutes. A resin particle dispersion for coating the aggregated particles, prepared by mixing 25 parts of polyester resin dispersion and 10 parts of ion-exchanged water and adjusting the pH to 3.0, was then added and held for 10 minutes. To stop the growth of the coated aggregated particles (adhered particles), a 1M aqueous sodium hydroxide solution was added to adjust the pH of the raw material mixture to 8.0. The temperature was then raised to 80°C at a rate of 1°C / min to fuse the aggregated particles. After reaching 80°C, the average circularity was measured every 30 minutes and held until it reached 0.966. The toner dispersion was then cooled to 40°C at a cooling rate of A1 = 60°C / min using a heat exchanger. A 0.3M aqueous nitric acid solution was added to adjust the pH, and the temperature was raised to 57°C. The pH was measured and found to be 7.5. The mixture was then held for 1 hour and cooled to 40°C. The resulting mixture was then filtered, redispersed in 3 liters of ion-exchanged water, and subjected to solid-liquid separation by Nutsche suction filtration, which was repeated six times to obtain a wet cake. The resulting mixture was then vacuum dried for 12 hours to obtain toner base particles (1) having an average volume particle size of 6.0 μm and an average circularity of 0.966. Next, 1.5 parts by weight of hydrophobic silica (TS720 manufactured by Cabot) was added to 50 parts by weight of the toner base particles and blended in a sample mill to obtain a toner with external additives. Next, the toner with external additives and the resin-coated ferrite carrier were mixed to prepare a developer with a toner concentration of 7% by weight.

[0162] <Example 2> (Preparation of specific resin particle dispersion 2) In the second step, specific resin particle dispersion 2 was prepared in the same manner as in Example 1, except that 5 minutes after the complete addition of the monomer-containing emulsion, 1,500 parts of ion-exchanged water (aqueous cooling medium) was started to be added dropwise to the reaction tank using a liquid transfer tube at an addition rate V1 of 19.5 parts / min. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 2.

[0163] Example 3 (Preparation of specific resin particle dispersion 3) In the second step, specific resin particle dispersion 3 was prepared in the same manner as in Example 1, except that immediately after the entire amount of the monomer-containing emulsion had been added, 1,500 parts of ion-exchanged water (aqueous cooling medium) was started to be added dropwise to the reaction tank using a liquid transfer tube at an addition rate V1 of 29.3 parts / min. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 3.

[0164] Example 4 (Preparation of specific resin particle dispersion 4) In the second step, specific resin particle dispersion 4 was prepared in the same manner as in Example 1, except that immediately after the entire amount of the monomer-containing emulsion had been added, 1,500 parts of ion-exchanged water (aqueous cooling medium) was started to be added dropwise to the reaction tank using a liquid transfer tube at an addition rate V1 of 9.8 parts / min. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 4.

[0165] <Example 5> (Preparation of specific resin particle dispersion 5) In the second step, immediately after the entire amount of the monomer-containing emulsion had been added, the addition of ion-exchanged water (aqueous cooling medium) was started at a rate of 19.5 parts / min, and the internal temperature was monitored every minute. Specific resin particle dispersion 5 was prepared in the same manner as in Example 1, except that the addition rate V1 of ion-exchanged water was changed based on the formula (1): V3 = V1 × a × ΔT, and a = 7.0. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 5.

[0166] Example 6 (Preparation of specific resin particle dispersion 6) In the second step, immediately after the entire amount of the monomer-containing emulsion had been added, the addition of ion-exchanged water (aqueous cooling medium) was started at a rate of 19.5 parts / min, and the internal temperature was monitored every minute. Specific resin particle dispersion 6 was prepared in the same manner as in Example 1, except that the addition rate V1 of ion-exchanged water was changed based on the formula (1): V3 = V1 × a × ΔT, and a = 5.6. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 6.

[0167] Example 7 (Preparation of specific resin particle dispersion 7) In the second step, specific resin particle dispersion liquid 7 was prepared in the same manner as in Example 1, except that the dropwise addition of ion-exchanged water (aqueous cooling medium) began 8 minutes after the complete addition of the monomer-containing emulsion. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 7.

[0168] Example 8 (Preparation of specific resin particle dispersion 8) In the second step, specific resin particle dispersion 8 was prepared in the same manner as in Example 1, except that immediately after the entire amount of the monomer-containing emulsion had been added, 1,500 parts of ion-exchanged water (aqueous cooling medium) was added dropwise to the reaction tank using a liquid transfer tube at an addition rate V1 of 31.2 parts / min. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 8.

[0169] Example 9 (Preparation of specific resin particle dispersion 9) In the second step, specific resin particle dispersion 9 was prepared in the same manner as in Example 1, except that immediately after the entire amount of the monomer-containing emulsion had been added, ion-exchanged water (aqueous cooling medium) was added dropwise to the reaction tank using a liquid transfer tube at an addition rate V1 of 7.8 parts / min. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 9.

[0170] Example 10 (Preparation of specific resin particle dispersion 10) In the second step, immediately after the entire amount of the monomer-containing emulsion had been added, the addition of ion-exchanged water (aqueous cooling medium) was started at a rate of 19.5 parts / min, and the internal temperature was monitored every minute. A specific resin particle dispersion 10 was prepared in the same manner as in Example 1, except that the addition rate V1 of ion-exchanged water was changed based on the formula (1): V3 = V1 × a × ΔT, and a = 7.2. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 10.

[0171] Example 11 (Preparation of specific resin particle dispersion 11) In the second step, immediately after the entire amount of the monomer-containing emulsion had been added, the addition of ion-exchanged water (aqueous cooling medium) was started at a rate of 19.5 parts / min, and the internal temperature was monitored every minute. Specific resin particle dispersion 11 was prepared in the same manner as in Example 1, except that the addition rate V1 of ion-exchanged water was changed based on the formula (1): V3 = V1 × a × ΔT, and a = 5.4. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 11.

[0172] Example 12 (Preparation of specific resin particle dispersion 12) In the second step, specific resin particle dispersion 12 was prepared in the same manner as in Example 1, except that the temperature of the ion-exchanged water (aqueous cooling medium) was set to 17°C 5 minutes after the complete addition of the monomer-containing emulsion. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 12.

[0173] Example 13 (Preparation of specific resin particle dispersion 13) In the second step, specific resin particle dispersion 13 was prepared in the same manner as in Example 1, except that the temperature of the ion-exchanged water (aqueous cooling medium) was adjusted to 33°C 5 minutes after the complete addition of the monomer-containing emulsion. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 13.

[0174] Example 14 (Preparation of specific resin particle dispersion 14) In the second step, specific resin particle dispersion 14 was prepared in the same manner as in Example 1, except that the temperature of the ion-exchanged water (aqueous cooling medium) was set to 13°C 5 minutes after the complete addition of the monomer-containing emulsion. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 14.

[0175] Example 15 (Preparation of specific resin particle dispersion 15) In the second step, specific resin particle dispersion 15 was prepared in the same manner as in Example 1, except that the temperature of the ion-exchanged water (aqueous cooling medium) was adjusted to 37°C 5 minutes after the complete addition of the monomer-containing emulsion. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 15.

[0176] Example 16 (Preparation of specific resin particle dispersion 16) In the second step, specific resin particle dispersion 16 was prepared in the same manner as in Example 1, except that the temperature of the ion-exchanged water (aqueous cooling medium) was set to 12°C 5 minutes after the complete addition of the monomer-containing emulsion. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 16.

[0177] Example 17 (Preparation of specific resin particle dispersion 17) In the second step, specific resin particle dispersion 17 was prepared in the same manner as in Example 1, except that the temperature of the ion-exchanged water (aqueous cooling medium) was set to 44°C 5 minutes after the complete addition of the monomer-containing emulsion. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 17.

[0178] Example 18 (Preparation of specific resin particle dispersion 18) Specific resin particle dispersion 18 was prepared in the same manner as in Example 1, except that the set temperature Tp of the aqueous base medium was set to 62°C in the first and second steps. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 18.

[0179] Example 19 (Preparation of specific resin particle dispersion 19) Specific resin particle dispersion 19 was prepared in the same manner as in Example 1, except that the set temperature Tp of the aqueous base medium was set to 78°C in the first and second steps. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 19.

[0180] Example 20 (Preparation of specific resin particle dispersion 20) A specific resin particle dispersion liquid 20 was prepared in the same manner as in Example 1, except that in the first step, n-butyl acrylate as the polymerizable monomer was changed to octyl acrylate. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 20.

[0181] Example 21 (Preparation of specific resin particle dispersion 21) Specific resin particle dispersion liquid 21 was prepared in the same manner as in Example 1, except that in the first step, the content of the (meth)acrylic acid-based monomer relative to the styrene-based monomer was set to 22% by mass. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 21.

[0182] Example 22 (Preparation of specific resin particle dispersion 22) Specific resin particle dispersion liquid 22 was prepared in the same manner as in Example 1, except that in the first step, the content of the (meth)acrylic acid-based monomer relative to the styrene-based monomer was set to 58 mass %. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 22.

[0183] Example 23 (Preparation of specific resin particle dispersion 23) Specific resin particle dispersion 23 was prepared in the same manner as in Example 1, except that in the second step, the monomer-containing emulsion was added from a liquid delivery pipe whose tip on the liquid discharge side was immersed in the aqueous mother medium, and the cooling aqueous medium was added by showering from above the liquid surface of the aqueous mother medium. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 23.

[0184] Example 24 (Preparation of specific resin particle dispersion 24) Specific resin particle dispersion liquid 24 was prepared in the same manner as in Example 1, except that in the second step, a liquid feed pipe was used in which the tip of the liquid discharge side of the liquid feed pipe was not immersed in the aqueous mother medium. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 24.

[0185] Example 25 (Preparation of specific resin particle dispersion 25) Specific resin particle dispersion liquid 25 was prepared in the same manner as in Example 1, except that in the second step, the temperature of the aqueous mother medium was maintained within a range of the set temperature to the set temperature + 1.4°C. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 25.

[0186] <Example 26> (Preparation of specific resin particle dispersion 26) Specific resin particle dispersion 26 was prepared in the same manner as in Example 1, except that in the second step, the temperature of the aqueous mother medium was maintained within a range of the set temperature to the set temperature minus 1.4°C. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 26.

[0187] Example 27 (Preparation of specific resin particle dispersion 27) Specific resin particle dispersion liquid 27 was prepared in the same manner as in Example 1, except that in the first step, the monomer-containing emulsion was added without being divided. (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid 27.

[0188] <Comparative Example 1> (Preparation of specific resin particle dispersion C1) In the second step, immediately after the entire amount of the monomer-containing emulsion was added, the solution in the reaction tank was post-heated at 65°C for 180 minutes to complete the reaction, and then cooled. A specific resin particle dispersion C1 was prepared in the same manner as in Example 1, except that (Toner and developer production) A toner and a developer were obtained in the same manner as in Example 1, except that the type of specific resin particle dispersion liquid added to the preparation of toner particles was changed to specific resin particle dispersion liquid C1.

[0189] <Color point evaluation> The resulting developer was loaded into the developing unit of an electrophotographic copier (Docu Centre Color 450, Fuji Xerox Co., Ltd.) with the fuser removed, and an unfixed image was output. The electrophotographic copier containing the developer was left in a high-temperature, high-humidity environment (temperature 30°C / relative humidity 85%) for one day, and then 1,000 images with 90% image density and 40 mm x 40 mm dimensions were continuously printed on one side of OKT127 paper under the same temperature and humidity conditions of 30°C / 85%. The printed images were visually inspected from the 901st to the 1,000th sheets to check for the occurrence of color spots. The color spots were evaluated according to the following criteria. A range up to G3 was considered acceptable. G1: No color dots G2: Color dots appear on 1 to 3 sheets G3: Color dots appear on 4 or more sheets but less than 5 sheets G4: Color dots appear on 6 or more sheets

[0190] <Low temperature fixability evaluation> The obtained electrostatic image developer was loaded into the developing unit of an electrophotographic copier (Docu Centre Color 450, manufactured by Fuji Xerox Co., Ltd.) from which the fixing unit had been removed, and an unfixed image was output. Using OKT127 paper as the recording medium, an unfixed image measuring 40 mm x 40 mm with an image density of 90% was formed on one side. The unfixed image was then fixed using a fixing evaluation device to evaluate low-temperature fixability. The fixing evaluation device used was a DocuPrint P450 manufactured by Fuji Xerox Co., Ltd., with the fixing unit removed and modified so that the fixing temperature could be changed. The fixing temperature was raised from 110°C to 160°C in 5°C increments, and the temperature (minimum fixing temperature) at which offset (a phenomenon in which an image is transferred to the fixing member due to insufficient melting of the toner image) no longer occurred was classified as follows: G2 and up were considered to be within the acceptable range. G1: Minimum fixing temperature is 130°C or less G2: Minimum fixing temperature is over 130℃ and below 140℃ G3: Minimum fixing temperature is over 140℃ and 150℃ or less G4: Minimum fixing temperature is over 150°C

[0191] (Coarse powder evaluation) The amount of coarse powder contained in the specific resin particles was evaluated by measuring the amount of coarse powder on a 200 mesh screen. The procedure for measuring the amount of coarse powder on the 200 mesh screen is as described above. The amount of coarse powder was evaluated based on the obtained measurements using the following evaluation criteria. G1 indicates the lowest coarse powder content, and G4 indicates the highest amount of coarse powder. Table 1 shows the evaluation results based on the following evaluation criteria, along with the amount of coarse powder on a 200-mesh screen. G1: The measured value of coarse powder on a 200 mesh screen is 0.3% or less G2: The measured value of coarse powder on a 200 mesh screen is more than 0.3% and less than 0.5% G3: The measured value of coarse powder on a 200 mesh screen is over 0.5% and 1.0% or less G4: The measured value of coarse powder on a 200 mesh screen is more than 1.0%

[0192] [Table 1-1]

[0193] [Table 1-2]

[0194] The descriptions in the table are explained below. "St / Ac" in the polymerizable monomer type indicates that the polymerizable monomer is a styrene-based monomer and a (meth)acrylic acid-based monomer. "Ac / St x 100" indicates the content of the (meth)acrylic acid-based monomer relative to the styrene-based monomer. The "temperature retention range" indicates the range of deviation of the temperature of the aqueous mother medium from the set temperature after the addition of the monomer-containing emulsion. For example, if "1.5°C" is written, this indicates that the temperature of the aqueous mother medium after the addition of the monomer-containing emulsion deviates from the set temperature in the range from the set temperature or higher to a temperature 1.5°C higher than the set temperature. Note that in Comparative Example 1, the notation "-" indicates that the deviation of the temperature of the aqueous mother medium from the set temperature was large (beyond the range of ±1.5°C of the set temperature), making it impossible to accurately indicate the range of deviation from the set temperature. "Same / different liquid supply pipe" indicates whether the liquid supply pipes for adding the monomer-containing emulsion and the cooling aqueous medium to the aqueous mother medium are the same or different.

[0195] From the above results, it can be seen that the resin particles of this example suppress the generation of coarse powder.

Claims

1. a first step of adding a monomer-containing emulsion containing a polymerizable monomer and an aqueous medium to an aqueous mother medium to polymerize the polymerizable monomer; a second step of adding a cooling aqueous medium to the aqueous mother medium after the addition of the monomer-containing emulsion to the aqueous mother medium is completed, maintaining the temperature of the aqueous mother medium within a range of a set temperature ±1.5°C after the addition of the monomer-containing emulsion; A method for producing resin particles.

2. 2. The method for producing resin particles according to claim 1, wherein in the second step, a cooling aqueous medium is added to the aqueous mother medium within 5 minutes after completion of the addition of the monomer-containing emulsion to the aqueous mother medium.

3. 3. The method for producing resin particles according to claim 1, wherein in the first step, a first monomer-containing emulsion containing a first polymerizable monomer as the polymerizable monomer is added to the aqueous mother medium, the first polymerizable monomer is polymerized to produce seed resin particles, and then a second monomer-containing emulsion containing a second polymerizable monomer as the polymerizable monomer is added, and the second polymerizable monomer is polymerized.

4. 4. The method for producing resin particles according to claim 3, wherein in the second step, when the addition rate of the aqueous cooling medium is V1, the specific heat of the aqueous cooling medium is C1, the addition rate of the second monomer-containing emulsion is V2, and the specific heat of the second monomer-containing emulsion is C2, the relationship satisfies 0.5≦V1C1 / V2C2≦1.

5.

5. 5. The method for producing resin particles according to claim 1, wherein, in the second step, when an addition rate of the aqueous cooling medium is V1 and an absolute value (|Tp-Tm|) of a difference between a set temperature Tp of the aqueous mother medium after completion of addition of the monomer-containing emulsion and an actual measured temperature Tm of the aqueous mother medium is ΔT, ΔT, V1, and an addition amount V3 of the aqueous cooling medium when the temperature of the aqueous mother medium changes by ΔT satisfy the following formulas (1) and (2): Formula (1): V3=V1×a×ΔT Formula (2): 5.6≦a≦7.0

6. 6. The method for producing resin particles according to claim 1, wherein the temperature of the cooling aqueous medium is Tm(0)-50°C or higher and Tm(0)-30°C or lower, where Tm(0) is the actual temperature of the aqueous mother medium at the end of addition of the monomer-containing emulsion.

7. 7. The method for producing resin particles according to claim 6, wherein the temperature of the aqueous cooling medium is 10°C or higher and 45°C or lower.

8. 8. The method for producing resin particles according to claim 6, wherein the temperature of the aqueous mother medium is 60°C or higher and 80°C or lower.

9. The method for producing resin particles according to any one of claims 1 to 8, wherein the polymerizable monomer is a styrene-based monomer and a (meth)acrylic acid-based monomer.

10. The method for producing resin particles according to claim 9, wherein the content of the (meth)acrylic acid-based monomer relative to the styrene-based monomer is 20% by mass or more and 60% by mass or less.

11. The method for producing resin particles according to any one of claims 1 to 10, wherein the monomer-containing emulsion and the cooling aqueous medium are added to the aqueous mother medium through the same liquid transfer pipe.

12. The method for producing resin particles according to claim 11, wherein the tip of the liquid delivery pipe on the liquid discharge side is immersed in the aqueous mother medium.

13. a step of aggregating at least the resin particles in a dispersion containing the resin particles obtained by the method for producing resin particles according to any one of claims 1 to 12 to form aggregated particles; a step of heating the aggregated particle dispersion in which the aggregated particles are dispersed to fuse and coalesce the aggregated particles to form toner particles; A method for producing a toner for developing electrostatic images, comprising:

Images