Toner manufacturing method

Abstract

To provide a toner manufacturing method with which coalescence of resin particles is prevented in a heat treatment step.SOLUTION: A toner manufacturing method has a preparation step of preparing an aqueous medium containing inorganic dispersant and fine bubbles, a granulation step of forming, in the aqueous medium, particles of a polymerizable monomer composition containing a polymerizable monomer and colorant, a polymerization step of polymerizing the polymerizable monomer to obtain resin particles, and a heat treatment step of performing heat treatment on the resin particles. The heat treatment step is (i) performed in an aqueous medium at a temperature of 60°C or more, and in which (ii) the fine bubbles are adsorbed on the surfaces of the resin particles. The number average particle diameter of the fine bubbles in the aqueous medium used in the preparation step is 1.0×101 nm or more and 5.0×102 nm or less. The abundance of the fine bubbles per 1 mL of the aqueous medium is 1.0×104 or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing toner used in electrophotography, electrostatic recording, and toner jet recording. [Background technology]

[0002] In recent years, there has been a demand for faster printing speeds and smaller bodies and cartridges in electrophotographic forming apparatuses. To make these demands possible, there is a demand for improved toner properties. For example, to contribute to the speed and size reduction of electrophotographic apparatuses, there is a demand for toner with good low-temperature fixability. This is because it can increase the process speed for fixing toner to paper and contribute to the size reduction of fixing members. In order to improve the performance of toner, further improvements are also required in the manufacturing method of toner. Toner manufacturing methods have been proposed, such as suspension polymerization and emulsion polymerization aggregation, in which a mixture of crystalline components such as polymerizable monomers, colorants, release agents, and crystalline resins is dispersed in an aqueous medium to obtain resin particles. Among these, suspension polymerization has the advantage of being able to encapsulate the release agent and crystalline resin in the center of a spherical structure and of easily controlling the shape, and is superior in developability and transferability to pulverization, which is a dry manufacturing method that does not use an aqueous medium. On the other hand, suspension polymerization also faces challenges. For example, resin particle coalescence during high-temperature heat treatment processes. In processes involving heating an aqueous medium, resin particles soften due to heating. As a result, resin particles in contact with each other in the medium coalesce, resulting in coarse particles and irregularly shaped particles. When coalescence occurs, the coalesced particles must be removed, leading to reduced yields. Furthermore, if the proportion of irregularly shaped particles in the toner increases due to coalescence, this adversely affects toner properties such as charging ability and development characteristics, leading to poor image characteristics such as fogging and dripping, which is undesirable. Toners with improved low-temperature fixability use soft resins to lower the temperature at which they adhere to paper. Therefore, they tend to coalesce more easily. Furthermore, recent changes in environmental trends have led to higher heat treatment temperatures to ensure the removal of organic volatile components. Therefore, suppressing particle coalescence during high-temperature heat treatment processes has become an important issue. As a means for suppressing coalescence during the heat treatment process, a method focusing on inorganic dispersants has been proposed. For example, Patent Document 1 proposes a toner manufacturing method in which the zeta potential of inorganic fine particles contained therein is adjusted during the polymerization and distillation processes. It is disclosed that the positive charge of the dispersant is adjusted to an appropriate value, so that the dispersant can be adsorbed with an appropriate adhesive force onto the surface of resin particles uniformly dispersed in an aqueous medium, thereby suppressing coalescence. Patent Document 2 proposes a method in which a liquid containing a poorly water-soluble inorganic substance is applied to at least a portion of the inner wall of a polymerization vessel used in the polymerization process. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-90510 [Patent Document 2] Japanese Patent Application Laid-Open No. 2010-152249 Summary of the Invention [Problem to be solved by the invention]

[0004] However, there is still room for improvement in the use of dispersants alone as a means of suppressing coalescence. This is because some areas of the resin particle surface remain uncoated with dispersants alone, which can become the starting point for coalescence. Further substances, means, and improved methods for preventing coalescence are needed. The present disclosure provides a method for producing a toner in which the coalescence of resin particles during a heat treatment step is suppressed. [Means for solving the problem]

[0005] The present invention provides a method for producing a toner, comprising: a preparation step of preparing an aqueous medium containing an inorganic dispersant and fine bubbles; a granulation step of forming particles of a polymerizable monomer composition containing a polymerizable monomer and a colorant in the aqueous medium; a polymerization step of polymerizing the polymerizable monomer to obtain resin particles; and a heat treatment step of heat treating the resin particles, The heat treatment step (i) carried out in an aqueous medium at a temperature of 60°C or higher; (ii) the fine bubbles are adsorbed on the surface of the resin particles; The number average particle size of the fine bubbles in the aqueous medium used in the preparation step is 1.0 × 10 1 nm or more 5.0×10 2 nm or less, and the amount of fine bubbles present per mL of the aqueous medium is 1.0 × 10 4 The toner manufacturing method is characterized in that the number of particles is at least 1. The present invention also provides a method for producing a toner, comprising: a preparation step of preparing an aqueous medium A containing an inorganic dispersant; a granulation step of forming particles of a polymerizable monomer composition containing a polymerizable monomer and a colorant in the aqueous medium; a polymerization step of polymerizing the polymerizable monomer to obtain resin particles; and a heat treatment step of heat treating the resin particles, Before the heat treatment step, an aqueous medium B containing fine bubbles is mixed, The heat treatment step (i) carried out in an aqueous medium at a temperature of 60°C or higher; (ii) the fine bubbles are adsorbed on the surface of the resin particles; When the volume of the aqueous medium A is Va [L], the volume of the aqueous medium B is Vb [L], the amount of fine bubbles present per mL in the aqueous medium B is Mb [pieces], and the number average particle diameter is Db [nm], Db is 1.0 × 10 1 Over 5.0 x 10 2 or less, and Mc [units] expressed by the following formula (1) is 1.0 × 10 4 The toner production method is characterized by the above. Mc=Mb×Vb / (Va+Vb) (1) [Effects of the Invention]

[0006] According to the present invention, it is possible to provide a method for producing a toner in which the coalescence of the toner particles during the heat treatment step is suppressed. DETAILED DESCRIPTION OF THE INVENTION

[0007] The present invention will be described in more detail below with reference to embodiments thereof, but is not limited thereto. Note that, unless otherwise specified, the expressions "XX or more and YY or less" or "XX to YY" representing a numerical range mean a numerical range including the lower and upper limits, which are the endpoints.

[0008] [Features of the present invention] The present invention can be suitably used in a method for producing resin particles by a suspension polymerization method using a polymerizable monomer or the like.

[0009] The toner manufacturing method of the present invention is a toner manufacturing method including: a preparation step of preparing an aqueous medium containing an inorganic dispersant and fine bubbles; a granulation step of forming particles of a polymerizable monomer composition containing a polymerizable monomer and a colorant in the aqueous medium; a polymerization step of polymerizing the polymerizable monomer to obtain resin particles; and a heat treatment step of heat treating the resin particles, The heat treatment step (i) carried out in an aqueous medium at a temperature of 60°C or higher; (ii) the fine bubbles are adsorbed on the surface of the resin particles; The number average particle size of the fine bubbles in the aqueous medium used in the preparation step is 1.0 × 10 1nm or more 5.0×10 2 nm or less, and the amount of fine bubbles present per mL of the aqueous medium is 1.0 × 10 4 This is a method for producing a toner characterized in that the number of particles is at least 1 (first aspect of the present invention).

[0010] By using such a method for producing a toner, it is possible to produce resin particles in which coalescence is suppressed.

[0011] The present inventors believe that the mechanism by which this effect is obtained is as follows.

[0012] To suppress coalescence, it is important to coat the resin particle surface with another substance, such as an inorganic dispersant. The higher the coverage, the greater the coalescence suppression effect. In this invention, fine bubbles are used in addition to an inorganic dispersant to coat the resin particle surface. The hydrophobic surface of fine bubbles exerts hydrophobic interactions with oily substances suspended in water. Therefore, when fine bubbles are contained in an aqueous medium, they adsorb to the resin particle surface. From the perspective of interfacial energy, fine bubbles are more stable in an adsorbed state than in a bubble state in water, so they remain on the resin particle surface. The fine bubbles that remain on the surface serve to protect the resin particles and three-dimensionally shield other resin particles, thereby suppressing coalescence. Fine bubbles have small particle sizes and are resistant to aggregation in water, allowing them to exist alone. Therefore, they can adsorb to small areas that are difficult to cover with inorganic dispersants and to areas with low charge on the toner surface. Therefore, using them in combination with an inorganic dispersant provides greater coalescence suppression. Furthermore, when fine bubbles are adsorbed onto the resin particle surface, the resin particles become less susceptible to thermal history even during the heating process due to the insulating effect of the fine bubbles present on the toner resin particle surface. The fact that fine bubbles are adsorbed onto the resin particle surface and that the resin particles are less susceptible to thermal history can be determined by measuring the methanol wettability half value of the resin particles, which will be described later.

[0013] As a result of the above, components such as wax that are localized in the center of the toner can be prevented from being excessively precipitated on the surface due to heat. These effects also result in toner particles with uniform circular shapes, allowing for uniform triboelectric charging, which in turn results in excellent developability, such as reduced fogging.

[0014] In the present invention, the number-average particle size of the fine bubbles contained in the aqueous medium used in the preparation step is 1.0 × 10 1 nm or more 5.0×10 2 By reducing the size of the fine bubbles, they can be densely adsorbed onto the toner surface, which leads to the suppression of coalescence.

[0015] Methods for controlling the particle size of fine bubbles include changing the conditions for producing fine bubbles and membrane separation, which separates the generated fine bubbles using a membrane.Membrane separation is a method of separating and classifying fine bubbles of the desired diameter by passing them through multiple filters with the desired pore size.

[0016] The amount of fine bubbles present per 1 mL of aqueous medium used in the preparation process is 1.0 x 10 4 1.0×10 or more, preferably 1.0×10 5 Increasing the concentration of fine bubbles increases the number of fine bubbles adsorbed to the toner surface, which leads to the suppression of coalescence.

[0017] One way to control the number concentration of fine bubbles per mL is to concentrate the fine bubbles by passing them through a membrane separation filter, thereby increasing their number. The number concentration can also be increased by circulating the fine bubbles through a known fine bubble generator. Conversely, the number concentration can be decreased by adding an aqueous medium to dilute the solution.

[0018] The aqueous medium containing fine bubbles is not limited to being used in the preparation step described above, but may be added in any step prior to the heat treatment step.

[0019] That is, the method for producing a toner includes a preparation step of preparing an aqueous medium A containing an inorganic dispersant, a granulation step of forming particles of a polymerizable monomer composition containing a polymerizable monomer and a colorant in the aqueous medium, a polymerization step of polymerizing the polymerizable monomer to obtain resin particles, and a heat treatment step of heat treating the resin particles, Before the heat treatment step, an aqueous medium B containing fine bubbles is mixed, The heat treatment step (i) carried out in an aqueous medium at a temperature of 60°C or higher; (ii) the fine bubbles are adsorbed on the surface of the resin particles; When the volume of the aqueous medium A is Va [L], the volume of the aqueous medium B is Vb [L], the amount of fine bubbles present per mL in the aqueous medium B is Mb [pieces], and the number average particle diameter is Db [nm], Db is 1.0 × 10 1 Over 5.0 x 10 2 or less, and Mc [units] expressed by the following formula (1) is 1.0 × 10 4 This is the case above (the second aspect of the present invention). Mc=Mb×Vb / (Va+Vb) (1)

[0020] Mc calculated by formula (1) is the number of fine bubbles per mL of the total aqueous medium contained in the heat treatment process. When fine bubbles are added only in the preparation process, the fine bubble concentration used in the preparation process will be the same as the number of fine bubbles per mL of the total aqueous medium contained in the heat treatment process.

[0021] In the present invention, the absolute value of the zeta potential of the fine bubbles is preferably 5 mV or more and 30 mV or less. It is believed that when the zeta potential of the fine bubbles is in this range, the charge of the fine bubbles becomes small. This reduces the electrical interaction with the resin particles, making them more likely to adsorb to the surface of the resin particles, thereby increasing the effect of suppressing coalescence.

[0022] Methods for controlling the zeta potential of fine bubbles include changing the type of gas that makes up the fine bubbles or changing the pH of the aqueous medium. If other substances are dissolved in the fine bubble water, it becomes difficult to measure the zeta potential of the fine bubbles. For this reason, the zeta potential of the fine bubbles was measured in ion-exchanged water that was adjusted to the pH of the liquid used in the heat treatment process.

[0023] Furthermore, when the number average particle size of the resin particles is a (μm) and the number average particle size of the fine bubbles is b (μm), it is preferable that the following formula (2) is satisfied. 14≦a / b (2)

[0024] The ratio a / b represents the size of resin particles relative to the fine bubbles. If the resin particles are large relative to the fine bubbles, the fine bubbles can be densely adsorbed to the resin particle surface. Furthermore, by not lowering the particle size ratio too much and keeping it within the above range, fine bubbles approaching the resin particles can be densely adsorbed to the resin surface without causing steric hindrance.

[0025] As a method for producing fine bubbles, any conventionally known method can be used without any particular limitation. Specific examples include methods based on gas phase dispersion by liquid flow shear, such as swirling liquid flow, static mixer, mechanical shear, micropore, and fluid vibration methods; methods based on changes in gas solubility in liquid, such as pressurized dissolution and thermal precipitation; methods based on cavitation, such as ejector, Venturi, and ultrasonic methods; methods based on phase changes in dispersed phases, such as mixed vapor condensation methods; and methods based on chemical changes in liquid phases, such as electrolysis methods.

[0026] Among these, methods based on cavitation are preferred because they enable efficient fine bubble generation. Below, a Venturi-type fine bubble production method will be described in detail as an example of a method based on cavitation, but the present invention is not limited to the following.

[0027] In the Venturi method of producing fine bubbles, a liquid containing the target gas dissolved in it is fed into a Venturi tube with a constricted section. As the liquid passes through the constricted section, its flow rate increases, causing it to be decompressed according to Bernoulli's theorem. When the pressure drops below the saturated vapor pressure of the gas, bubbles are generated in the liquid due to cavitation. After passing through the constricted section, the liquid is re-pressurized as the flow rate decreases, and the generated bubbles collapse under the pressure, generating fine bubbles.

[0028] [Constituent materials of resin particles and toner] Materials that can be used for the resin particles and toner according to the present invention will be described below.

[0029] <Binder resin> In the present invention, a binder resin for a toner is obtained by polymerizing a polymerizable monomer.

[0030] Vinyl resins are preferred as binder resins, as they can easily increase the adsorptive properties between fine bubbles and resin particles when the absolute value of the zeta potential of the fine bubbles is 5 mV or more and 30 mV or less.

[0031] <Vinyl resin> Examples of vinyl resins that can be used include polymers or copolymers of vinyl monomers such as styrene monomers typified by styrene and α-methylstyrene; unsaturated carboxylic acid esters typified by methyl acrylate, butyl acrylate, methyl methacrylate, 2-hydroxyethyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, and stearyl methacrylate; unsaturated carboxylic acids typified by acrylic acid and methacrylic acid; unsaturated dicarboxylic acids typified by maleic acid; unsaturated dicarboxylic anhydrides typified by maleic anhydride; nitrile vinyl monomers typified by acrylonitrile; halogen-containing vinyl monomers typified by vinyl chloride; and nitro vinyl monomers typified by nitrostyrene.

[0032] <Polymerization initiator> Examples of the polymerization initiator for obtaining the vinyl resin include organic peroxide initiators and azo polymerization initiators.

[0033] Examples of organic peroxide initiators include benzoyl peroxide, lauroyl peroxide, di-α-cumyl peroxide, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, bis(4-t-butylcyclohexyl)peroxydicarbonate, 1,1-bis(t-butylperoxy)cyclododecane, t-butylperoxymaleic acid, bis(t-butylperoxy)isophthalate, methyl ethyl ketone peroxide, tert-butylperoxy-2-ethylhexanoate, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, and tert-butylperoxypivalate.

[0034] Examples of the azo polymerization initiator include 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobismethylbutyronitrile, and 2,2'-azobis-(methyl isobutyrate).

[0035] The polymerization initiator is selected based on its 10-hour half-life temperature and is used alone or in combination. The amount of polymerization initiator added varies depending on the desired degree of polymerization, but is generally 0.5 to 20.0 parts by mass per 100.0 parts by mass of polymerizable monomer.

[0036] <Polar resin> In the present invention, it is preferable to use a resin containing a carboxy group as the polar resin. By adding a polar resin to the polymerizable monomer composition, a shell can be formed in the granulation and polymerization steps. Therefore, the SP value of the resin particle surface is a value derived from the polar resin.

[0037] The SP value (J / cm3 ) 0.5 The SP value is preferably 19.5 or more and 22.1 or less. By controlling the SP value within the above range, the action of the fine bubbles hydrophobically adsorbing to the resin particle surface and the action of the inorganic dispersant electrostatically adsorbing can be achieved at the same time, thereby enhancing the effect of suppressing coalescence.

[0038] The polar resin can be obtained by selecting and combining suitable compounds from polycarboxylic acids, polyols, hydroxycarboxylic acids, etc., and synthesizing them using a conventionally known method such as transesterification or polycondensation.

[0039] <Release agent> The resin particles according to the present invention may contain a release agent.

[0040] Examples of release agents include petroleum waxes such as paraffin wax, microcrystalline wax, and petrolatum and their derivatives, montan wax and its derivatives, hydrocarbon waxes produced by the Fischer-Tropsch process and their derivatives, polyolefin waxes such as polyethylene and polypropylene and their derivatives, and natural waxes such as carnauba wax and candelilla wax and their derivatives. Derivatives also include oxides, block copolymers with vinyl monomers, and graft-modified products.

[0041] Other examples include alcohols such as higher aliphatic alcohols, fatty acids such as stearic acid and palmitic acid or their acid amides, esters, and ketones, hydrogenated castor oil and its derivatives, vegetable waxes, and animal waxes.These may be used alone or in combination.

[0042] The content of the release agent is preferably 1.0 part by mass or more and 20.0 parts by mass or less with respect to 100.0 parts by mass of the binder resin.

[0043] The melting point of the release agent is preferably 30° C. or higher and 120° C. or lower, and more preferably 60° C. or higher and 100° C. or lower. By using a release agent with a melting point of 30° C. or higher and 120° C. or lower, the release effect is efficiently exerted and a wider fixing area is ensured.

[0044] <Coloring agent> Known pigments and dyes can be used as colorants, with pigments being preferred as colorants due to their excellent weather resistance.

[0045] Examples of cyan colorants include copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, and basic dye lake compounds.

[0046] Specific examples include: CI Pigment Blue 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62 and 66.

[0047] Examples of magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds.

[0048] Specific examples include CI Pigment Red 2, 3, 5, 6, 7, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 144, 146, 150, 166, 169, 177, 184, 185, 202, 206, 220, 221 and 254, and CI Pigment Violet 19.

[0049] Examples of yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds.

[0050] Specific examples include the following: CI Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 185, 191 and 194.

[0051] Examples of black colorants include those toned to black using the above yellow colorants, magenta colorants, and cyan colorants, as well as CI Pigment Red 122.

[0052] These colorants can be used alone or in mixture, or further in the state of a solid solution.

[0053] The colorant is preferably used in an amount of 1.0 part by mass or more and 20.0 parts by mass or less with respect to 100.0 parts by mass of the binder resin.

[0054] <Charge control agents and charge control resins> The resin particles may contain a charge control agent or a charge control resin. Known charge control agents can be used, and particularly, charge control agents that have a high frictional charging speed and can stably maintain a constant frictional charge amount are preferred.

[0055] Examples of substances that control the toner to be negatively charged include monoazo metal compounds, acetylacetone metal compounds, aromatic oxycarboxylic acids, aromatic dicarboxylic acids, oxycarboxylic and dicarboxylic acid-based metal compounds, aromatic oxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, phenol derivatives such as bisphenol, urea derivatives, metal-containing salicylic acid-based compounds, metal-containing naphthoic acid-based compounds, boron compounds, calixarenes, and charge control resins.

[0056] Examples of the charge control resin include polymers or copolymers having sulfonic acid groups, sulfonate salt groups, or sulfonate ester groups. As the polymer having sulfonic acid groups, sulfonate salt groups, or sulfonate ester groups, a polymer containing 2% by mass or more, more preferably 5% by mass or more, of a sulfonate group-containing acrylamide monomer or a sulfonate group-containing methacrylamide monomer in copolymerization ratio is preferred.

[0057] These charge control agents or charge control resins may be added singly or in combination of two or more kinds.

[0058] The amount of the charge control agent or charge control resin added is preferably 0.01 to 20.0 parts by mass, more preferably 0.5 to 10.0 parts by mass, relative to 100.0 parts by mass of the binder resin.

[0059] <External additives> If necessary, an external additive may be added to the toner. Examples of such an external additive include inorganic oxide particles such as silica particles, alumina particles, and titanium oxide particles; inorganic stearic acid compound particles such as aluminum stearate particles and zinc stearate particles; and inorganic titanic acid compound particles such as strontium titanate and zinc titanate. These may be used alone or in combination of two or more.

[0060] These inorganic particles are preferably surface-treated with a silane coupling agent, a titanium coupling agent, a higher fatty acid, a silicone oil, etc. The BET specific surface area of ​​the external additive is 10 m 2 / g or more 450m 2 / g or less is preferable.

[0061] The BET specific surface area can be determined by a low-temperature gas adsorption method using a dynamic constant pressure method in accordance with the BET method (preferably the BET multipoint method). For example, a specific surface area measuring device (trade name: Gemini 2375 Ver. 5.0, manufactured by Shimadzu Corporation) is used to adsorb nitrogen gas onto the surface of a sample, and the BET multipoint method is used to measure the BET specific surface area (m 2 / g) can be calculated.

[0062] The total amount of these various external additives added is preferably 0.05 parts by mass or more and 5 parts by mass or less, more preferably 0.1 parts by mass or more and 3 parts by mass or less, relative to 100 parts by mass of resin particles. Various external additives may also be used in combination.

[0063] [Toner manufacturing method] The toner production method of the present invention is based on a suspension polymerization method, and the production method using the suspension polymerization method will be described below step by step.

[0064] The suspension polymerization method is a production method in which particles of a polymerizable monomer composition containing a polymerizable monomer and a colorant are formed in an aqueous medium, and the polymerizable monomer contained in the particles of the polymerizable monomer composition is polymerized to obtain resin particles.

[0065] (Preparation step of preparing inorganic dispersant) An aqueous medium containing an inorganic dispersant is prepared. Examples of inorganic dispersants include carbonates such as barium carbonate, calcium carbonate, and magnesium carbonate; metal phosphates such as aluminum phosphate, magnesium phosphate, calcium phosphate, hydroxyapatite, barium phosphate, and zinc phosphate; sulfates such as barium sulfate and calcium sulfate; and metal hydroxides such as calcium hydroxide, aluminum hydroxide, magnesium hydroxide, and ferric hydroxide. These can be used alone or in combination. These function as dispersants by being present in the aqueous medium as water-insoluble inorganic fine particles. Furthermore, calcium-containing metal phosphates such as calcium phosphate and hydroxyapatite are preferred because the zeta potential can be controlled by adjusting the pH of the aqueous solvent.

[0066] When the zeta potential of the inorganic dispersant is φb (mV), the absolute value of φb is preferably 3 or more and 15 or less, and when the zeta potential of the fine bubbles is φa (mV), the relationship between φa and φb is more preferably expressed by the following formula (3). 25≦|φa|×|φb|≦300 (3)

[0067] When fine bubbles contained in an aqueous medium come into contact with an inorganic dispersant, it has the effect of loosening aggregates of the inorganic dispersant, reducing the frequency of coalescence even with the same amount of inorganic dispersant. By keeping |φa|×|φb| at 25 or more, the range in which the fine bubbles and inorganic dispersant can come into electrical contact is maintained. Furthermore, by keeping |φa|×|φb| at 300 or less, it is possible to prevent the inorganic dispersant and fine bubbles from coming into electrical contact and then becoming stuck.

[0068] (Preparation step of polymerizable monomer composition) A polymerizable monomer composition containing a polymerizable monomer and a colorant is prepared. The colorant may be dispersed in the polymerizable monomer in advance using a medium stirring mill or the like and then mixed with other compositions, or may be dispersed after all of the compositions have been mixed. It is also preferable to add a polar resin during the preparation.

[0069] (granulation process) A polymerizable monomer composition is added to an aqueous medium containing an inorganic dispersant, and granulated by dispersion to obtain a polymerizable monomer composition dispersion. The granulation process can be carried out, for example, in a vertical stirring tank equipped with a high-shear stirrer. The high-shear stirrer is not particularly limited, but commercially available stirrers such as a High Shear Mixer (manufactured by IKA Corporation), a Homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), TK Filmix (manufactured by Tokushu Kika Kogyo Co., Ltd.), and Clearmix (manufactured by M Technique Co., Ltd.) can be used.

[0070] (Polymerization process) The polymerizable monomer in the polymerizable monomer composition dispersion obtained as described above is polymerized to obtain a dispersion of resin particles. The polar resin forms a shell during the granulation and polymerization steps. A general temperature-controllable stirring tank can be used for the polymerization step in the present invention.

[0071] The polymerization temperature is 40° C. or higher, and generally 50 to 90° C. The polymerization temperature may be constant throughout, but may be increased in the latter half of the polymerization step in order to obtain a desired molecular weight distribution.

[0072] Any stirring blade may be used for stirring as long as it can suspend the polymerizable monomer composition dispersion without stagnation and maintain a uniform temperature in the tank. Examples of the stirring blade or stirring means include common stirring blades such as paddle blades, inclined paddle blades, triple swept blades, propeller blades, disk turbine blades, helical ribbon blades, and anchor blades, as well as "Fullzone" (manufactured by Kobe Steel Pantech Co., Ltd.), "Twinstar" (manufactured by Kobe Steel Pantech Co., Ltd.), "Maxblend" (manufactured by Sumitomo Heavy Industries, Ltd.), "Supermix" (manufactured by Satake Chemical Machinery Co., Ltd.), and "Hi-F Mixer" (manufactured by Soken Chemical & Engineering Co., Ltd.).

[0073] (Heat treatment process) The heat treatment process is a process for removing volatile impurities, such as unreacted polymerizable monomers and by-products, from the dispersion of resin particles obtained in the polymerization process, and is carried out in an aqueous medium at 60°C or higher. The organic volatile component removal process can be carried out under normal pressure or reduced pressure, and various removal methods can be used to remove organic volatile components to the desired concentration. Considering the efficiency of removing organic volatile components, it is desirable that the temperature of the aqueous medium in the heat treatment process be at least 30°C above the glass transition temperature (Tg) of the resin particles.

[0074] Furthermore, it is preferable that the coverage of the inorganic dispersant on the resin particle surface during the heat treatment step be 20% to 70% by area. A coverage of 20% or more ensures minimal coverage of the dispersant, which, combined with the effect of the fine bubbles, can suppress coalescence. A coverage of 70% or less ensures that the fine bubbles are sufficiently adsorbed onto the resin particle surface, suppressing coalescence and protecting the resin through the insulating effect of the fine bubbles, while also suppressing precipitation of the release agent.

[0075] (Washing process, filtration process) In order to remove the inorganic dispersant adhering to the surface of the resin particles, the dispersion of resin particles is treated with an acid or alkali. After this, the polymer particles are separated from the liquid phase by a general solid-liquid separation method, but the resin particles are washed again with water to completely remove the acid or alkali and the inorganic dispersant components dissolved therein. This washing process is repeated several times, and after sufficient washing, solid-liquid separation is again performed to obtain wet resin particles.

[0076] (drying process) The drying step is a step of removing moisture contained in the wet resin particles obtained in the filtration step. A conventionally known drying method can be used for the drying step of the present invention without any particular limitations. Specific examples include vacuum drying, fluidized bed drying, and airflow drying. Among these, a loop airflow dryer is preferred because it uniformly applies heat using a drying gas and allows for good separation of dried resin particles from undried resin particles. Examples of loop airflow dryers include a flash jet dryer (manufactured by Seishin Enterprise Co., Ltd.) and a jet turbo dryer (manufactured by Hiraiwa Iron Works Co., Ltd.).

[0077] (Classification process) The classification step is a step of removing small and / or large particles from the resin particles, and may be performed depending on the desired particle size and particle size distribution of the resin particles.

[0078] (External addition process) The external addition step is a step of mixing the obtained resin particles (toner particles) with an external additive, and attaching the external additive to the surface of the resin particles to impart properties such as fluidity and chargeability, thereby obtaining a toner. The external addition step may be performed depending on the required toner properties. If the external addition step is not performed, the resin particles obtained in the drying step or classification step can be used as a toner as is.

[0079] The mixer for externally adding the external additive to the resin particles is not particularly limited, and any known mixer, whether dry or wet, can be used. Examples include FM Mixer (manufactured by Nippon Coke & Engineering Co., Ltd.), Super Mixer (manufactured by Kawata Corporation), Nobilta (manufactured by Hosokawa Micron Corporation), and Hybridizer (manufactured by Nara Kikai Co., Ltd.). To control the coating state of the external additive, the toner can be prepared by adjusting the rotation speed, processing time, and water temperature and amount in the jacket of the external addition device.

[0080] In addition, examples of sieving devices used to sift out coarse particles after external addition include Ultrasonic (manufactured by Koei Sangyo Co., Ltd.); Resonaseave, Gyrosifter (Tokuju Kogyo Co., Ltd.); Vibrasonic System (manufactured by Dalton Co., Ltd.); Soniclean (manufactured by Shinto Kogyo Co., Ltd.); Turbo Screener (manufactured by Turbo Kogyo Co., Ltd.); and Microsifter (manufactured by Makino Sangyo Co., Ltd.).

[0081] [Methods for measuring physical properties] The methods for measuring the physical properties of the toner and each material will be described below.

[0082] <Method for measuring the number average particle size (D1) of resin particles (toner particles)> The number-average particle size (D1) of resin particles (toner particles) is calculated as follows. The measurement device used is a precision particle size distribution measurement device using the narrow-pore electrical resistance method, the Coulter Counter Multisizer 3 (registered trademark, manufactured by Beckman Coulter, Inc.), equipped with a 100 μm aperture tube. The measurement conditions are set and the measurement data is analyzed using the accompanying dedicated software, Beckman Coulter Multisizer 3 Version 3.51 (manufactured by Beckman Coulter, Inc.). The measurement is performed using an effective number of measurement channels of 25,000.

[0083] The aqueous electrolyte solution used for the measurement is prepared by dissolving special grade sodium chloride in ion-exchanged water to a concentration of approximately 1% by mass, such as "ISOTON II" (manufactured by Beckman Coulter).

[0084] Before measurements and analyses were carried out, the dedicated software was set up as follows.

[0085] On the "Change Standard Measurement Method (SOMME)" screen of the dedicated software, set the total count in control mode to 50,000 particles, the number of measurements to 1, and the Kd value to the value obtained using "Standard Particles 10.0 μm" (Beckman Coulter). Press the "Threshold / Noise Level Measurement Button" to automatically set the threshold and noise level. Also, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and check "Flush aperture tube after measurement."

[0086] On the "Pulse to particle size conversion setting" screen of the dedicated software, the bin interval is set to logarithmic particle size, the particle size bin is set to 256 particle size bins, and the particle size range is set to 2 μm to 60 μm.

[0087] The specific measurement method is as follows. (1) Pour approximately 200 ml of the electrolyte solution into a 250 ml round-bottom glass beaker made specifically for the Multisizer 3, set it on the sample stand, and stir the stirrer rod counterclockwise at 24 revolutions per second. Then, use the "aperture flush" function of the dedicated software to remove any dirt and air bubbles from inside the aperture tube. (2) Approximately 30 ml of the above-mentioned aqueous electrolyte solution is placed in a 100 ml flat-bottom glass beaker, and approximately 0.3 ml of a dilution of Contaminon N (a 10% aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) diluted approximately three times by mass with ion-exchanged water is added as a dispersant. (3) Prepare an ultrasonic disperser "Ultrasonic Dispension System Tetra150" (manufactured by Nikkaki Bios Co., Ltd.) with an electrical output of 120 W and two built-in oscillators with an oscillation frequency of 50 kHz and a phase difference of 180 degrees. Place approximately 3.3 L of ion-exchanged water in the ultrasonic disperser's water tank, and add approximately 2 mL of Contaminon N to this water tank. (4) Set the beaker (2) in the beaker fixing hole of the ultrasonic disperser, operate the ultrasonic disperser, and adjust the height of the beaker so that the resonance state of the liquid surface of the electrolytic solution in the beaker is maximized. (5) While the electrolyte solution in the beaker in (4) is irradiated with ultrasonic waves, approximately 10 mg of toner is added little by little to the electrolyte solution and dispersed. The ultrasonic dispersion process is then continued for another 60 seconds. During the ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted to be between 10°C and 40°C. (6) Using a pipette, add the electrolyte solution (5) containing the dispersed toner to the round-bottom beaker (1) placed in the sample stand, and adjust the measurement concentration to approximately 5%. Then, measure the particle count until it reaches 50,000 particles. (7) The measurement data is analyzed using the dedicated software attached to the device to calculate the number-average particle size (D1).

[0088] <Measurement of glass transition temperature (Tg) of resin particles (toner particles)> The glass transition temperature (Tg) was measured using a differential scanning calorimeter "Q1000" (manufactured by TA Instruments) in accordance with ASTM D3418-82. The melting points of indium and zinc were used for temperature correction of the detector, and the heat of fusion of indium was used for heat correction. was used. Specifically, approximately 3 mg of resin particles were precisely weighed and placed in an aluminum pan. An empty aluminum pan was used as a reference, and measurements were performed within a measurement range of 30 to 200°C at a temperature increase rate of 10°C / min. During this temperature increase, specific heat changes were obtained in the temperature range of 40 to 100°C. The line extending the baseline before the specific heat change was determined as the first line, the line extending the baseline after the specific heat change was determined as the second line, and the line equidistant in the vertical direction from the first and second lines was determined as the third line. The temperature at the intersection of the third line and the stepwise change portion of the differential thermal curve (the so-called midpoint glass transition temperature) was determined as the glass transition temperature Tg of the resin particles.

[0089] <Method for measuring the coverage of inorganic dispersant on resin particle surfaces> The coverage rate is measured for resin particles dispersed in an aqueous medium in the resin particle dispersion process. The resin particle dispersion is subjected to pressure filtration and thoroughly air-dried to obtain resin particles. The filter paper used is Advantec's quantitative filter paper No. 5C. The resulting resin particles are used for measurement according to the following procedure.

[0090] The coverage rate is calculated by analyzing resin particle surface images taken with a Hitachi ultra-high resolution field emission scanning electron microscope S-4800 (Hitachi High-Technologies Corporation) using image analysis software Image-Pro Plus ver. 5.0 (Nippon Roper Co., Ltd.). The image capture conditions for the S-4800 are as follows:

[0091] (1) Sample preparation Apply a thin layer of conductive paste to a sample stage (aluminum sample stage 15 mm x 6 mm), then spray resin particles onto it. Then, use air to remove excess resin particles from the sample stage and allow it to dry thoroughly. Place the sample stage in the sample holder and adjust the sample stage height to 36 mm using the sample height gauge.

[0092] (2) Setting the S-4800 observation conditions Pour liquid nitrogen into the anti-contamination trap attached to the S-4800 housing until it overflows and leave it for 30 minutes. Start the S-4800's "PC-SEM" and perform flushing (cleaning the FE chip, which is the electron source). Click the accelerating voltage display area on the control panel on the screen and press the [Flushing] button to open the flushing execution dialog. Confirm that the flushing intensity is 2 and execute it. Confirm that the emission current due to flushing is 20-40 μA. Insert the sample holder into the sample chamber of the S-4800 housing. Press [Origin] on the control panel to move the sample holder to the observation position.

[0093] Click the accelerating voltage display to open the HV setting dialog, and set the accelerating voltage to [0.8 kV] and the emission current to [20 μA]. In the [Basic] tab of the operation panel, set the signal selection to [SE], select [Upper (U)] and [+BSE] for the SE detector, and select [LA100] in the selection box to the right of [+BSE] to set the mode for observation using backscattered electron images. Also in the [Basic] tab of the operation panel, set the probe current in the electron optical system condition block to [Normal], the focus mode to [UHR], and the WD to [3.0 mm]. Press the [ON] button in the accelerating voltage display on the control panel to apply the accelerating voltage.

[0094] (3) Calculation of the number average particle size (D) of the toner Drag within the magnification display area of ​​the control panel to set the magnification to 5000 (5k).

[0095] Rotate the focus knob [COARSE] on the operation panel until the image is in focus to some extent, then adjust the aperture alignment. Click [Align] on the control panel to display the alignment dialog and select [Beam]. Rotate the STIGMA / ALIGNMENT knobs (X, Y) on the operation panel to move the displayed beam to the center of the concentric circles. Next, select [Aperture] and rotate the STIGMA / ALIGNMENT knobs (X, Y) one by one to stop the image movement or adjust it so that it moves as little as possible. Close the aperture dialog and use autofocus to adjust the focus.

[0096] Repeat this process two more times to adjust the focus.

[0097] Then, the particle diameters of 300 resin particles are measured and the average is calculated to determine the average particle diameter (D). The particle diameter of each particle is the maximum diameter observed when the resin particle is observed.

[0098] (4) Focus adjustment For particles within ±0.1 μm of the average particle size (D) obtained in (3), align the midpoint of the maximum diameter with the center of the measurement screen, and drag within the magnification display section of the control panel to set the magnification to 10,000 (10k) times.

[0099] Rotate the focus knob [COARSE] on the operation panel until the image is in focus to some extent, then adjust the aperture alignment. Click [Align] on the control panel to display the alignment dialog and select [Beam]. Rotate the STIGMA / ALIGNMENT knobs (X, Y) on the operation panel to move the displayed beam to the center of the concentric circles. Next, select [Aperture] and rotate the STIGMA / ALIGNMENT knobs (X, Y) one by one to stop the image movement or adjust it so that it moves as little as possible. Close the aperture dialog and use autofocus to adjust the focus.

[0100] After that, set the magnification to 5000 (5k) times, and adjust the focus using the focus knob and STIGMA / ALIGNMENT knob as above, then use autofocus again to focus. Repeat this operation to adjust the focus. Here, if the tilt angle of the observation surface is large, the accuracy of the coverage measurement is likely to be low, so when adjusting the focus, select an object that will bring the entire observation surface into focus at the same time, and select an object with as little surface tilt as possible for analysis.

[0101] (5) Save image Adjust the brightness in ABC mode, take a photo at a size of 640 x 480 pixels, and save it. Use this image file for the following analysis. Take one photo for each resin particle, and obtain images of at least 30 particles.

[0102] (6) Image analysis The image obtained using the above method is binarized using the following analysis software to calculate the coverage. At this time, the above screen is divided into 12 squares and each is analyzed.

[0103] The analysis procedure using the image analysis software Image-Pro Plus ver. 5.0 is as follows.

[0104] The SEM image is imported into the image analysis software and subjected to a 3x3 pixel filtering process. Next, the area A of a single resin particle is calculated from the outline of the resin particle. Furthermore, binarization is performed within the outline of the resin particle. In this case, a threshold calculated by automatic processing is used as the binarization threshold. For example, inorganic dispersants are identified as black.

[0105] Then, the area marked in black is obtained as B. The coverage of the inorganic dispersant is calculated using the following formula: Inorganic dispersant coverage (area%) = Area B / Area A × 100

[0106] <Calculation method for SP value of resin particle surface> The SP value of the resin particle surface is calculated as follows, according to the calculation method proposed by Fedors: For each polar resin, the evaporation energy (Δei) (J / mol) and molar volume (Δvi) (cm) for each atom or atomic group in the molecular structure are calculated from the table in "Polym. Eng. Sci., 14(2), 147-154 (1974)." 3 / mol), and calculate (ΣΔei / ΣΔvi) 0.5 SP value (J / cm 3 ) 0.5 Let's say.

[0107] The SP value of the resin particle surface is calculated by calculating the evaporation energy (Δei) and molar volume (Δvi) of the monomer unit derived from the monomer constituting the polar resin for each monomer unit, calculating the product of each monomer unit and the molar ratio (j) of each monomer unit in the resin, and dividing the sum of the evaporation energy of each monomer unit by the sum of the molar volumes, {(Σj×ΣΔei) / (Σj×ΣΔvi)} 0.5 SP value (J / cm 3 ) 0.5 Let's say.

[0108] <Zeta potential measurement of inorganic dispersants> In order to eliminate the influence of other dissolved substances such as fine bubbles, the zeta potential of the inorganic dispersant was measured using the inorganic dispersant dispersed in ion-exchanged water.

[0109] The zeta potential value (ζt) and the standard deviation (σt) of the average value of the zeta potential of the inorganic dispersant in the present invention were measured using a Zetasizer Nano ZS (manufactured by MALVERN) and the accompanying dedicated software "Dispersion Technology software 4.20" (manufactured by MALVERN) for setting measurement conditions and analyzing measurement data. The specific measurement method is as follows.

[0110] (1) An aqueous medium containing an inorganic dispersant was produced without using fine bubble water, and then a 10% by mass aqueous solution of hydrochloric acid / sodium hydroxide was added to adjust the pH to correspond to the heat treatment step in each example.

[0111] (2) Immediately afterwards, a portion of the aqueous medium was withdrawn from the preparation vessel and transferred to a 10 mL syringe. Next, the tip of the syringe was inserted into one of the sample ports of a capillary cell for zeta potential measurement (DTS1060-Clear disposable zeta cell), which had been washed twice with ion-exchanged water, and the aqueous medium was slowly poured into the cell to avoid the formation of air bubbles. After confirming that the liquid had been poured into the capillary without any gaps, the two sample ports were plugged.

[0112] (3) The cell was inserted into the cell holder of the measuring device, and the lid of the detection section was closed. Measurement was carried out under the following measurement conditions. F(ka)selection Model:Smoluchowski Dispersant:Water Temperature: Polymerization or distillation temperature (usually 70°C) Result Calculation:General Purpose (4) After the measurement was completed, the "Zeta Potential" value on the measurement result report screen was taken as the average value of the zeta potential.

[0113] <Number-average particle size and number concentration of fine bubbles> The number-average particle size and number concentration of fine bubbles are measured as follows using a particle size measuring device, ViewSizer 3000 (manufactured by HORIBA), which utilizes the particle tracking method.

[0114] An aqueous medium containing fine bubbles is prepared as a sample.

[0115] 2 ml of the measurement sample is poured into a quartz cell (High Precision Cell: manufactured by Hellma Analytic, 10 x 10 mm) equipped with a stir bar and dedicated jig that come with the device, and the cell is then set in the cell holder of the device.

[0116] Launch Nano tracking analysis from the application provided with the device and perform measurements with the following settings.

[0117] Target temperature: 22 #of videos:30 Frames per second: 30 Exposure: 18 Gain:24 Stirring time:5 Video length:300 Laser power B:70 G:12 R:8 After the measurement is completed, the Average size value (nm) on the displayed measurement results screen is the number-average particle size of the fine bubbles, and the Particle Concentration value (particles / mL) is the number concentration of the fine bubbles.

[0118] When measuring, turn stirring on in Streaming mode and check that the outlines of the fine bubbles on the image displayed are clear, and with stirring off, check that there is little overlap between the fine bubbles on the image. If the outlines are unclear, use the Focus function to adjust the focus. If there is significant overlap between the fine bubbles, dilute the sample. If the sample is diluted, multiply the obtained Particle Concentration value by the dilution factor to obtain the fine bubble number concentration.

[0119] <Zeta potential of fine bubbles> The zeta potential of fine bubbles is measured as follows using a zeta potential measuring device, ZetaSizer Nano ZSP (manufactured by Malvern), which utilizes electrophoretic light scattering.

[0120] An aqueous medium containing fine bubbles was prepared as a sample, and then the pH was adjusted to correspond to the pH during the heat treatment step in each example.

[0121] A disposable capillary cell for zeta potential measurement (DTS1060, manufactured by Malvern) is filled with a measurement sample, and the cell is set in the cell holder of the device.

[0122] Select zeta potential measurement from the application provided with the device and perform the measurement under the following conditions. F(ka)selection Model:Smoluchowski Dispersant:Water Temperature: 25℃ Result Calculation:General Purpose After the measurement is completed, the "Zeta Potential" value (mV) displayed on the measurement results report screen is the zeta potential of the fine bubbles.

[0123] <Method for measuring aspect ratio> The aspect ratio of the resin particles (toner particles) was measured using a flow particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation) under the measurement and analysis conditions used during calibration. The specific measurement method is as follows:

[0124] First, approximately 20 mL of ion-exchanged water, from which impurities such as solids have been removed, is placed in a glass container. Approximately 0.2 mL of a solution prepared by diluting "Contaminon N" (a 10% by weight aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) approximately three times by weight with ion-exchanged water is added. Approximately 0.04 g of the sample to be measured is then added, and the mixture is dispersed for 2 minutes using an ultrasonic disperser to obtain a dispersion for measurement. The dispersion is then cooled appropriately so that its temperature is between 10°C and 40°C. A tabletop ultrasonic cleaner disperser with an oscillation frequency of 50 kHz and an electrical output of 150 W (e.g., "VS-150" manufactured by Vervoclear Co., Ltd.) is used as the ultrasonic disperser. A predetermined amount of ion-exchanged water is then placed in a water tank, and approximately 2 mL of the Contaminon N is added to the tank.

[0125] For the measurements, the flow particle image analyzer described above equipped with a "LUCPLFLN" objective lens (magnification 20x, numerical aperture 0.40) was used, and the particle sheath "PSE-900A" (manufactured by Sysmex Corporation) was used as the sheath liquid. The dispersion prepared according to the above procedure was introduced into the flow particle image analyzer, and 2,000 toner particles were measured in HPF measurement mode and total count mode. The binarization threshold for particle analysis was set to 85%, and the analyzed particle diameter was calculated as the circle-equivalent diameter (number) limited to 4.044 μm or more and less than 100.0 μm.

[0126] Before starting the measurement, automatic focus adjustment is performed using standard latex particles (for example, Duke Scientific's "RESEARCH AND TEST PARTICLES Latex Microsphere Suspensions 5100A" diluted with ion-exchanged water). After that, it is preferable to perform focus adjustment every two hours from the start of the measurement.

[0127] In the examples of the present application, a flow-type particle image analyzer was used that had been calibrated by Sysmex Corporation and had a calibration certificate issued by Sysmex Corporation. Measurements were performed under the same measurement and analysis conditions as when the calibration certificate was received, except that the particle diameters analyzed were limited to a circle-equivalent diameter (number) of 4.044 μm or more and less than 100.0 μm.

[0128] <Wettability measurement> The wettability of the resin particles (toner particles), that is, the hydrophobicity, was determined from the methanol drop transmittance curve obtained as follows.

[0129] First, 60 mL of RO (reverse osmosis) water was placed in a cylindrical glass container with a diameter of 5 cm and a thickness of 1.75 mm, and the measurement sample was dispersed for 5 minutes using an ultrasonic disperser to remove air bubbles and the like.

[0130] Next, the resin particles were sieved through a mesh with 150 μm openings, and 0.1 g of the toner that passed through the mesh was precisely weighed and added to the container containing the ion-exchanged water to prepare a measurement sample liquid. The measurement sample liquid was then set in a powder wettability tester "WET-100P" (manufactured by Rhesca Co., Ltd.). This measurement sample liquid was stirred for 5.0 s using a magnetic stirrer. -1 The mixture was stirred at a speed of 300 rpm. The rotor of the magnetic stirrer was a fluororesin-coated spindle rotor with a length of 20 mm and a maximum body diameter of 5 mm.

[0131] Next, the transmittance was measured at 780 nm while continuously adding methanol to the sample solution at a rate of 0.8 mL / min through the device, and a methanol drop transmittance curve was created. The methanol concentration (volume %) at 50% transmittance on the methanol drop transmittance curve was defined as the methanol wettability half value.

[0132] When the methanol wettability half value is large, it suggests that the resin particles have been subjected to a strong thermal history, causing hydrophobic substances such as release agents to appear on the surface of the resin particles. When toner is manufactured using such resin particles, the fluidity of the toner is reduced, leading to image defects such as development streaks.

[0133] [Configurations included in the embodiments of the present invention] The disclosure of this embodiment includes the following configuration. (Configuration 1) A method for producing a toner, comprising: a preparation step of preparing an aqueous medium containing an inorganic dispersant and fine bubbles; a granulation step of forming particles of a polymerizable monomer composition containing a polymerizable monomer and a colorant in the aqueous medium; a polymerization step of polymerizing the polymerizable monomer to obtain resin particles; and a heat treatment step of heat treating the resin particles, The heat treatment step (i) carried out in an aqueous medium at a temperature of 60°C or higher; (ii) the fine bubbles are adsorbed on the surface of the resin particles; The number average particle size of the fine bubbles in the aqueous medium used in the preparation step is 1.0 × 10 1 nm or more 5.0×10 2 nm or less, and the amount of fine bubbles present per mL of the aqueous medium is 1.0 × 10 4 1. A method for producing a toner, comprising: (Configuration 2) A method for producing a toner, comprising: a preparation step of preparing an aqueous medium A containing an inorganic dispersant; a granulation step of forming particles of a polymerizable monomer composition containing a polymerizable monomer and a colorant in the aqueous medium; a polymerization step of polymerizing the polymerizable monomer to obtain resin particles; and a heat treatment step of heat treating the resin particles, Before the heat treatment step, an aqueous medium B containing fine bubbles is mixed, The heat treatment step (i) carried out in an aqueous medium at a temperature of 60°C or higher; (ii) the fine bubbles are adsorbed on the surface of the resin particles; When the volume of the aqueous medium A is Va [L], the volume of the aqueous medium B is Vb [L], the amount of fine bubbles present per mL in the aqueous medium B is Mb [pieces], and the number average particle diameter is Db [nm], Db is 1.0 × 10 1 Over 5.0 x 10 2 or less, and Mc [units] expressed by the following formula (1) is 1.0 × 10 4 The method for producing a toner is characterized by the above. Mc=Mb×Vb / (Va+Vb) (1) (Configuration 3) The method for producing a toner according to Configuration 1 or 2, wherein the temperature of the aqueous medium in the heat treatment step is the glass transition temperature (Tg) of the resin particles + 30° C. or higher. (Configuration 4) The method for producing a toner according to any one of Configurations 1 to 3, wherein the surfaces of the resin particles are coated with the inorganic dispersant, and the coverage is 20 area % or more and 70 area % or less. (Configuration 5) The SP value (J / cm) of the surface of the resin particles 3 ) 0.5 5. The method for producing a toner according to any one of configurations 1 to 4, wherein the σ is 19.5 or more and 22.1 or less. (Configuration 6) The fine bubbles are added to the aqueous medium in an amount of 1.0 × 10 5 6. The method for producing a toner according to any one of configurations 1 to 5, wherein the toner contains at least one of the above-mentioned compounds / mL. (Configuration 7) The method for producing a toner according to any one of Configurations 1 to 6, wherein the absolute value of φa (mV) is 5 or more and 30 or less, when the zeta potential of the fine bubbles is φa. (Configuration 8) A method for producing a toner according to any one of Configurations 1 to 7, wherein the following formula (2) is satisfied when the number average particle diameter of the resin particles is a (μm) and the number average particle diameter of the fine bubbles is b (μm): 14≦a / b (2) (Configuration 9) The method for producing a toner according to Configuration 7, wherein when the zeta potential of the inorganic dispersant is φb (mV), the relationship between φa and φb satisfies the following formula (3): 25≦|φa|×|φb|≦300 (3) [Example]

[0134] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto. "Parts" used in the examples are by mass unless otherwise specified.

[0135] An example of toner production will be described below.

[0136] [Example of production of fine bubble-containing water] <Production of Fine Bubble Water A> Ion-exchanged water containing dissolved air was prepared and passed through a fine bubble generator, the UP0290M 100V motor type (Shibata Co., Ltd.), to produce fine bubble water A. The number-average particle size and number concentration of the produced fine bubbles were 150 nm and 1.70 x 10, respectively. 6 The number was 1 / mL.

[0137] <Production of Fine Bubble Water B> Deionized water containing dissolved air was prepared, and a pipe equipped with an SPG membrane filter (manufactured by SPG Techno Co., Ltd.) with a pore size of 0.5 μm was placed inside the deionized water. Air was then introduced into the pipe at a pressure of 0.2 MPa to produce fine bubble-containing water B. The number-average diameter and number concentration of the fine bubbles produced were 490 nm and 1.7 × 10, respectively. 5 The number was 1 / mL.

[0138] <Production of Fine Bubble Water C> Fine bubble-containing water C was prepared by diluting ultra-fine air bubble (nanobubble) water (Nanox Co., Ltd.) with 50,000 times the amount of ion-exchanged water. The particle size and number concentration of the fine bubbles produced were 55 nm and 1.68 × 10 5 The number was 1 / mL.

[0139] <Production of Fine Bubble Water D> Fine bubble-containing water D was produced in the same manner as in the production example for fine bubble-containing water A, except that ion-exchanged water in which oxygen was dissolved by bubbling oxygen gas was used instead of ion-exchanged water in which air was dissolved. The number-average particle size and number concentration of the produced fine bubbles were 150 nm and 1.70 × 10 6 The number was 1 / mL.

[0140] <Production of Fine Bubble Water E> Fine bubble-containing water E was produced in the same manner as in the production example for fine bubble-containing water B, except that the filter diameter was changed to 1 μm. The number-average particle size and number concentration of the produced fine bubbles were 1000 nm and 1.70 × 10 6 The number was 1 / mL.

[0141] <Production of Fine Bubble-Containing Water 1-16> The produced fine bubble waters A to E were diluted with ion-exchanged water to produce fine bubble-containing waters 1 to 16. The type of fine bubble water, dilution ratio, and physical properties of fine bubble-containing waters 1 to 16 are shown in Table 1.

[0142] [Table 1]

[0143] [Preparation example of aqueous medium containing inorganic dispersant and fine bubbles] <Preparation of aqueous medium 1> A vessel equipped with a stirrer, condenser, thermometer, and nitrogen inlet tube was charged with 303.9 parts by mass of fine bubble-containing water 1, 4.14 parts by mass of sodium phosphate dodecahydrate, and 1.65 parts by mass of 10% by mass hydrochloric acid to prepare a sodium phosphate aqueous solution, which was then heated to 50°C. A calcium chloride aqueous solution prepared by dissolving 2.38 parts by mass of calcium chloride dihydrate in 20.1 parts by mass of fine bubble-containing water 1 was added to the vessel, and the mixture was stirred at 7500 rpm for 30 minutes using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.). This yielded an aqueous medium 1 containing calcium phosphate (fine particles) and fine bubbles as an inorganic dispersant. The volume Va of the resulting aqueous medium 1 was measured. As a result, the volume of the aqueous medium 1 was equal to the total volume of the fine bubble-containing water 1 used to prepare the aqueous medium 1.

[0144] <Aqueous medium 2~20> Aqueous media 2 to 20 were produced in the same manner as in the production example of aqueous medium 1, except that the amounts of fine bubble-containing water, sodium phosphate dodecahydrate, 10% by mass hydrochloric acid, and calcium chloride dihydrate used in the production example of aqueous medium 2 were changed to those shown in Table 2. The volume of each of the obtained aqueous media 2 to 20 was measured. As a result, the volume of each aqueous medium was equal to the total volume of the fine bubble-containing water used to produce that aqueous medium.

[0145] [Table 2]

[0146] [Example of polar resin production] <Polar resin 1> 300 parts by mass of xylene (boiling point 144°C) was charged into an autoclave equipped with a pressure reducing device, a water separator, a nitrogen gas introducing device, a temperature measuring device, and a stirrer, and the inside of the container was thoroughly replaced with nitrogen while stirring, and then the temperature was raised and refluxed. Styrene 57.2 parts by mass Methyl methacrylate 37.0 parts by mass 3.3 parts by mass of methacrylic acid 2.5 parts by mass of 2-hydroxyethyl methacrylate Initiator: Di-tert-butyl peroxide 2.0 parts by mass After adding the mixed solution, polymerization was carried out for 5 hours at a polymerization temperature of 170°C and a pressure of 0.150 MPa during the reaction. A desolvation step was then carried out under reduced pressure for 3 hours to remove the xylene and crush the mixture to obtain Polar Resin 1. The Tg of Polar Resin 1 was 93.5°C.

[0147] <Polar resin 2> 300 parts by mass of xylene (boiling point 144°C) was charged into an autoclave equipped with a pressure reducing device, a water separator, a nitrogen gas introducing device, a temperature measuring device, and a stirrer, and the inside of the container was thoroughly replaced with nitrogen while stirring, and then the temperature was raised and refluxed. Styrene 78.4 parts by mass Methyl methacrylate 20.0 parts by mass Methacrylic acid 1.7 parts by mass Initiator: Di-tert-butyl peroxide 2.2 parts by mass After adding the mixed solution, the polymerization temperature was raised to 140°C and polymerization was carried out under atmospheric pressure for 5 hours. Then, a solvent removal step was carried out under reduced pressure for 3 hours to remove the xylene and crush the mixture to obtain Polar Resin 2. The Tg of Polar Resin 2 was 92.0°C.

[0148] <Polar resin 3> 300 parts by mass of xylene (boiling point 144°C) was charged into an autoclave equipped with a pressure reducing device, a water separator, a nitrogen gas introducing device, a temperature measuring device, and a stirrer, and the inside of the container was thoroughly replaced with nitrogen while stirring, and then the temperature was raised and refluxed. Styrene 73.4 parts by mass Methyl methacrylate 25.0 parts by mass Methacrylic acid 1.7 parts by mass Initiator: Di-tert-butyl peroxide 2.2 parts by mass After adding the mixed solution, the polymerization temperature was raised to 140°C and polymerization was carried out under atmospheric pressure for 5 hours. Thereafter, a solvent removal step was carried out under reduced pressure for 3 hours to remove the xylene, and the mixture was pulverized to obtain Polar Resin 3. The Tg of Polar Resin 3 was 92.3°C.

[0149] <Polar resin 4> Isophthalic acid 48.0 parts by mass Bisphenol A-propylene oxide 1 mole addition product 128 parts by mass Catalyst: Potassium titanium oxalate 0.035 parts by mass The above materials were placed in an autoclave equipped with a pressure reducer, water separator, nitrogen gas inlet, temperature measuring device, and stirrer. The reaction was carried out under a nitrogen atmosphere at atmospheric pressure at 220°C for 20 hours, followed by a further reaction under reduced pressure of 10 to 20 mmHg for 1.0 hour. The temperature was then lowered to 170°C, and 0.15 parts by mass of trimellitic anhydride was added. The reaction was carried out at 170°C for 1.0 hour, and after the temperature was lowered, the mixture was pulverized to obtain polar resin 4. The Tg of polar resin 4 was 79.5°C.

[0150] <Polar resin 5> Terephthalic acid 48.0 parts by mass Bisphenol S-propylene oxide 1 mole addition product 128 parts by mass Catalyst: Potassium titanium oxalate 0.035 parts by mass The above materials were placed in an autoclave equipped with a pressure reducer, water separator, nitrogen gas inlet, temperature measuring device, and stirrer. The reaction was carried out at 220°C for 20 hours under nitrogen atmosphere and atmospheric pressure, followed by an additional 1.0 hour reaction under reduced pressure of 10 to 20 mmHg. The temperature was then lowered to 170°C, and 0.15 parts by mass of trimellitic anhydride was added. The reaction was carried out at 170°C for 1.0 hour, and after the temperature was lowered, the mixture was pulverized to obtain Polar Resin 5. The Tg of Polar Resin 5 was 70.4°C.

[0151] [Preparation of Colorant Fine Particle Dispersion] Polymerizable monomer: styrene 39.0 parts by mass Pigment: Carbon black (manufactured by Orion Engineered Carbons, product name "Printex 35") 5.65 parts by weight Charge control agent (Orient Co., Ltd.: Bontron E-89) 0.23 parts by weight The above materials were placed in an Attritor disperser (Mitsui Miike Chemical Engineering Co., Ltd.), and further dispersed using zirconia particles with a diameter of 1.7 mm at 220 rpm for 5 hours to obtain a colorant particle dispersion.

[0152] [Example of Toner Particle Production] <Toner Particles 1 (Example 1)> (Preparation of Polymerizable Monomer Composition 1) The following materials were placed in a container and mixed and dispersed at 5000 rpm using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to obtain a polymerizable monomer composition 1. Colorant particle dispersion 44.9 parts by mass Styrene 31.0 parts by mass n-Butyl acrylate 30.0 parts by mass ·Polar resin 1 14.1 parts by mass Microcrystalline wax (Hi-Mic-2065; Nippon Seiro Co., Ltd.) 11.3 parts by mass

[0153] (granulation process) Polymerizable monomer composition 1 was added to 332.2 parts by mass of aqueous medium 1 prepared in the preparation of an aqueous medium containing an inorganic dispersant, and the mixture was stirred at 6,000 rpm in a homomixer for 5 minutes while maintaining the temperature at 65° C. to perform granulation. 10.6 parts by mass of the polymerization initiator t-butyl peroxypivalate (10-hour half-life temperature: 58° C.) was added thereto, and the mixture was further stirred for 1 minute.

[0154] (Polymerization process) The dispersion of the polymerizable monomer composition after the granulation step was transferred to another tank and heated to 70° C. while stirring with a paddle stirring blade. After the temperature was raised, stirring was continued for an additional 4 hours.

[0155] (Heat treatment process) The pH of the dispersion after the polymerization step was measured and found to be 5.5. The dispersion was heated to 100°C while continuing to stir, and heated for 4.0 hours to remove residual monomers. This resulted in a dispersion in which resin particles were dispersed in an aqueous medium. The pH of the dispersion remained unchanged at 5.5.

[0156] (Washing / Filtering / Drying) After cooling, hydrochloric acid was added to adjust the pH to 1.4, and the mixture was stirred for 2 hours to obtain a dispersion of toner particles. The dispersion of toner particles was filtered, washed with water, and then dried at a temperature of 40°C for 48 hours to obtain toner particles 1. The Tg (°C) of toner particles 1 was 55.2°C, and the number average particle size was 6.8 μm.

[0157] <Toner Particles 3 to 8 (Examples 3 to 8), 14 to 21 (Examples 14 to 21), 25 to 28 (Examples 25 to 28), and 33 to 36 (Comparative Examples 1 to 4)> Toner particles 3 to 8, 14 to 21, 25 to 28, and 33 to 36 were obtained in the same manner as in the production example of toner particle 1, except that the type and number of parts of the aqueous medium and the type of polar resin used were as shown in Table 1.

[0158] <Toner Particles 2 (Example 2)> (Preparation of Polymerizable Monomer Composition 2) The following materials were placed in a container and mixed and dispersed at 5000 rpm using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to obtain a polymerizable monomer composition 2. Colorant particle dispersion 44.9 parts by mass Styrene 31.0 parts by mass n-Butyl acrylate 30.0 parts by mass ·Polar resin 1 14.1 parts by mass Microcrystalline wax (Hi-Mic-2065; Nippon Seiro Co., Ltd.) 11.3 parts by mass

[0159] (granulation process) Polymerizable monomer composition 2 was added to 299.8 parts by mass of aqueous medium 2 prepared in the preparation of an aqueous medium containing an inorganic dispersant, and the mixture was stirred at 6,000 rpm in a homomixer for 5 minutes while maintaining the temperature at 65° C. to perform granulation. 10.6 parts by mass of the polymerization initiator t-butyl peroxypivalate (10-hour half-life temperature: 58° C.) was then added, and the mixture was further stirred for 1 minute.

[0160] (Polymerization process) The dispersion of the polymerizable monomer composition after the granulation step was transferred to another tank and heated to 70° C. while stirring with a paddle stirring blade. After the temperature was raised, stirring was continued for an additional 4 hours.

[0161] (Heat treatment process) While stirring with a paddle impeller, 32.4 parts by mass of fine bubble water 2 was added to the dispersion after the polymerization process. The pH of the dispersion after adding the fine bubble water was measured and found to be 5.5. While continuing to stir, the dispersion was heated to 100°C and heated for 4.0 hours to remove residual monomers. This resulted in a dispersion in which resin particles were dispersed in an aqueous medium. The pH of the dispersion remained unchanged at 5.5.

[0162] (Washing / Filtering / Drying) After cooling, hydrochloric acid was added to adjust the pH to 1.4, and the mixture was stirred for 2 hours to obtain a dispersion of toner particles. The dispersion of toner particles was filtered, washed with water, and then dried at 40°C for 48 hours to obtain toner particles 2. The Tg (°C) of toner particles 2 was 55.2°C, and the number average particle size was 6.3 μm.

[0163] <Toner Particles 9 to 13 (Examples 9 to 13), 24 (Example 24), and 37 to 39 (Comparative Examples 5 to 7)> Toner particles 9 to 13, 24, and 37 to 39 were obtained in the same manner as in the production example of toner particle 2, except that the type and number of parts of the aqueous medium used and the type of fine bubble-containing water added were as shown in Table 3.

[0164] <Toner Particles 22 (Example 22)> (Preparation of Polymerizable Monomer Composition 22) The following materials were placed in a container and mixed and dispersed at 5000 rpm using a homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.) to obtain a polymerizable monomer composition 22. Colorant particle dispersion 44.9 parts by mass Styrene 31.0 parts by mass n-Butyl acrylate 30.0 parts by mass ·Polar resin 1 14.1 parts by mass Microcrystalline wax (Hi-Mic-2065; Nippon Seiro Co., Ltd.) 11.3 parts by mass

[0165] (granulation process) Polymerizable monomer composition 22 was added to 303.9 parts by mass of aqueous medium 13 prepared in the preparation of an aqueous medium containing an inorganic dispersant, and the mixture was stirred at 6,000 rpm in a homomixer for 5 minutes while maintaining the temperature at 65° C. to perform granulation. 10.6 parts by mass of polymerization initiator t-butyl peroxypivalate (10-hour half-life temperature: 58° C.) was added thereto, and the mixture was further stirred for 1 minute.

[0166] (Polymerization process) The dispersion of the polymerizable monomer composition after the granulation step was transferred to another tank and heated to 70° C. while stirring with a paddle stirring blade. After the temperature was raised, stirring was continued for an additional 4 hours.

[0167] (Heat treatment process) While stirring with a paddle impeller, 32.4 parts by mass of fine bubble-containing water 2 was added to the dispersion after the polymerization process. The pH of the dispersion after adding the fine bubble water was measured and found to be 5.5. A 10% aqueous HCl solution was added to adjust the pH to 5.0. While continuing to stir, the dispersion was heated to 100°C and heated for 6.0 hours to remove residual monomers. This resulted in a dispersion in which resin particles were dispersed in an aqueous medium. The pH of the dispersion remained unchanged and remained at 5.0.

[0168] (Washing / Filtering / Drying) After cooling, hydrochloric acid was added to adjust the pH to 1.4, and the mixture was stirred for 2 hours to obtain a dispersion of toner particles. The dispersion of toner particles was filtered, washed with water, and then dried at 40°C for 48 hours to obtain toner particles 22. The Tg (°C) of toner particles 22 was 55.2°C, and the number average particle size was 6.8 μm.

[0169] <Toner Particles 23 (Example 23), 29 to 32 (Examples 29 to 32)> Toner particles 23 and 29 to 32 were obtained in the same manner as in the production example of toner particle 22, except that the type of aqueous medium used was as shown in Table 3.

[0170] Table 3 shows the manufacturing conditions for each toner particle (resin particle), and Table 4 shows the physical properties.

[0171] [Table 3]

[0172] [Table 4]

[0173] [Toner Production Example] <Toner 1> 100.0 parts by mass of toner particles 1 were mixed with 1.0 part by mass of hydrophobic silica fine powder surface-treated with dimethylsilicone oil in an FM mixer (manufactured by Nippon Coke Co., Ltd.) for 10 minutes, and then sieved through a mesh with 200 μm openings to obtain toner 1.

[0174] <Toner 2-39> Toners 2 to 39 were obtained in the same manner as in the production example of Toner 1, except that the types of toner particles (resin particles) used were as shown in Table 5. 〔evaluation〕 The obtained toner particles were subjected to the following evaluations.

[0175] <Aspect ratio evaluation> The aspect ratio (minor axis / major axis) is used as an index showing whether or not the resin particles are coalesced.

[0176] When there is little coalescence of particles and the particle image is more circular, the aspect ratio R approaches 1, and the more coalescence of particles and the higher the acicularity of the particle image, the smaller the aspect ratio R becomes. If the aspect ratio R of the resin particles is small, the sphericity of the resin particles decreases, and the toner produced using the resin particles will not be charged uniformly, leading to poor developability such as fogging. The evaluation ranks for each are as follows: A: 0.925 or higher B: 0.900 or more and less than 0.925 C: 0.880 or more and less than 0.900 D: 0.865 or more and less than 0.880 E: Less than 0.865

[0177] <Wettability evaluation> If the methanol wettability half value is large, it suggests that the resin particles have been subjected to a strong thermal history, causing hydrophobic substances such as release agents to appear on the surface of the resin particles. Toners using such resin particles tend to aggregate, which can lead to image defects such as development streaks in durability evaluations. The methanol wettability half value of the obtained resin particles was measured. The respective evaluation ranks are as follows: Methanol wettability half value (volume %) A: Less than 15.0 B: 15.0 or more and less than 18.0 C: 18.0 or more and less than 21.0 D:21.0 or more

[0178] The evaluation results are shown in Table 5.

[0179] [Table 5]

[0180] Next, the obtained toner was subjected to the following evaluations.

[0181] <Fogging evaluation> The image forming apparatus used was a modified laser printer (product name: LBP-9650Ci, manufactured by Canon Inc.) and a process cartridge (product name: Toner Cartridge 323, manufactured by Canon Inc.) The image forming apparatus was modified by changing the gear and software of the evaluation machine body to change the process speed to 350 mm / sec.

[0182] The product toner was removed from the black cartridge, and after cleaning with an air blower, 250 g of the toner of the present invention was refilled. The product toner was removed from each of the yellow, magenta, and cyan stations, and yellow, magenta, and black cartridges with their remaining toner detection mechanisms disabled were inserted for evaluation. Durability tests were conducted under normal temperature and humidity conditions (23°C, 50% RH). CS-680 sold by Canon Marketing Japan was used as the durability paper, and the durability evaluation chart used an image with a horizontal line coverage of 1.5%. 21,000 images were printed out in a sequence with a 4-second pause after every two prints. Immediately after printing, the prints were printed on Brochure Paper 150g Glossy (HP: 150 g / m 2 The fog density on the all-white image was calculated and evaluated according to the following criteria.

[0183] To measure fogging, a Tokyo Denshoku Reflectance Densitometer, Model TC-6DS, was used to measure the reflectance of the standard paper and the non-image area of ​​the printout image. A green filter was used for the measurement. From the measurement results, fogging was calculated using the following formula and evaluated according to the following criteria. Fog (reflectance: %) = reflectance on standard paper (%) - reflectance of non-image area of ​​sample (%) A: Fog (reflectance) less than 0.50% B: Fog (reflectance) is 0.50% or more and less than 2.0% C: Fog (reflectance) is 2.0% or more and less than 4.0% D: Fog (reflectance) 4.0 or more

[0184] <Evaluation of development streaks> After the above-mentioned fog evaluation, high whiteness paper (product name: GF-C081, manufactured by Canon Inc., 81.4 g / m 2 A half-tone image was printed out on the developing roller and the number of streaks was evaluated. The cartridge was also disassembled and the number of streaks on the developing roller was counted. (Evaluation criteria) A: No development streaks were observed on the developing roller. B: Streaks occurred on the developing roller, but did not appear in the halftone image. C: Many streaks occurred on the developing roller, but did not appear in the halftone image. D: Many streaks were observed on the developing roller, and white streaks were also observed in halftone images.

[0185] The evaluation results are shown in Table 6.

[0186] [Table 6]

Claims

1. A method for producing a toner, comprising: a preparation step of preparing an aqueous medium containing an inorganic dispersant and fine bubbles; a granulation step of forming particles of a polymerizable monomer composition containing a polymerizable monomer and a colorant in the aqueous medium; a polymerization step of polymerizing the polymerizable monomer to obtain resin particles; and a heat treatment step of heat treating the resin particles, The heat treatment step (i) carried out in an aqueous medium at a temperature of 60°C or higher; (ii) the fine bubbles are adsorbed on the surface of the resin particles; The number average particle size of the fine bubbles in the aqueous medium used in the preparation step is 1.0 × 10 1 nm or more 5.0×10 2 nm or less, and the amount of fine bubbles present per mL of the aqueous medium is 1.0 × 10 4 1. A method for producing a toner, comprising:

2. A method for producing a toner, comprising: a preparation step of preparing an aqueous medium A containing an inorganic dispersant; a granulation step of forming particles of a polymerizable monomer composition containing a polymerizable monomer and a colorant in the aqueous medium; a polymerization step of polymerizing the polymerizable monomer to obtain resin particles; and a heat treatment step of heat treating the resin particles, Before the heat treatment step, an aqueous medium B containing fine bubbles is mixed, The heat treatment step (i) carried out in an aqueous medium at a temperature of 60°C or higher; (ii) the fine bubbles are adsorbed on the surface of the resin particles; When the volume of the aqueous medium A is Va [L], the volume of the aqueous medium B is Vb [L], the amount of fine bubbles present per mL in the aqueous medium B is Mb [number], and the number average particle diameter is Db [nm], Db is 1.0 × 10 1 Above 5.0 x 10 2 or less, and Mc [units] represented by the following formula (1) is 1.0 × 10 4 The method for producing a toner is characterized by the above. Mc=Mb×Vb / (Va+Vb) (1)

3. 3. The method for producing a toner according to claim 1, wherein the temperature of the aqueous medium in the heat treatment step is a glass transition temperature (Tg) of the resin particles + 30[deg.] C. or higher.

4. 3. The method for producing a toner according to claim 1, wherein the surfaces of the resin particles are coated with the inorganic dispersant, and the coating rate is 20 area % or more and 70 area % or less.

5. The SP value (J / cm) of the resin particle surface 3 ) 0.5 3. The method for producing a toner according to claim 1, wherein the σ is 19.5 or more and 22.1 or less.

6. The fine bubbles were added to the aqueous medium at a concentration of 1.0 × 10 5 The method for producing a toner according to claim 1 or 2, wherein the toner contains at least one of the above-mentioned compounds / mL.

7. 3. The method for producing a toner according to claim 1, wherein the absolute value of φa (mV) of the zeta potential of the fine bubbles is 5 or more and 30 or less.

8. 3. The method for producing a toner according to claim 1, wherein the following formula (2) is satisfied, where a (μm) is the number average particle diameter of the resin particles and b (μm) is the number average particle diameter of the fine bubbles: 14≦a / b (2)

9. 8. The method for producing a toner according to claim 7, wherein when the zeta potential of the inorganic dispersant is φb (mV), the relationship between φa and φb satisfies the following formula (3): 25≦|φa|×|φb|≦300 (3)

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