Pigment-containing polyester resin particle, method for producing pigment-containing polyester resin particle, method for producing toner for electrostatic charge image development, electrostatic charge image developing toner, electrostatic charge image developer, toner cartridge, process cartridge, image formation device and image formation method

Abstract

To provide pigment-containing polyester resin particles with fewer coarse particles.SOLUTION: The pigment-containing polyester resin particles contain a polyester resin and a pigment, and the pigment is not exposed to a surface of the pigment-containing polyester resin particles and is not inscribed in the contour of the pigment-containing polyester resin particles.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present disclosure relates to pigment-containing polyester resin particles, a method for producing pigment-containing polyester resin particles, a toner for developing electrostatic images, an electrostatic image developer, a toner cartridge, a process cartridge, an image forming apparatus, and an image forming method. [Background technology]

[0002] Patent Document 1 discloses a color toner for developing electrostatic images, which contains colored resin particles containing at least a binder resin, a colorant, a charge control agent, and a release agent, and an external additive, in which the colorant is a resin-coated pigment whose surface is coated with a resin and has an average primary particle size of 30 to 300 nm, and the resin-coated pigment contains a tetrahydrofuran-insoluble content of 80 to 100 mass % of the coating resin. Patent Document 2 describes a method for preparing an aqueous pigment dispersion containing an organic pigment P, a surfactant T, and water, and then: -5 A method for making an aqueous dispersion of a polymer-encapsulated pigment is disclosed, comprising: (a) preparing a monomer microemulsion in water, the monomer microemulsion being stabilized by a hydrophobic organic compound having a water solubility of 0.1 g / l or less and consisting of a polymerizable monomer M and a surfactant T; (b) generating a pigment-containing monomer microemulsion by combining and homogenizing the aqueous pigment dispersion from (a) and the monomer microemulsion from (b); and (c) polymerizing the pigment-containing monomer microemulsion from (c) in the presence of a polymerization initiator and / or by heat, with the pigment being encapsulated by the forming polymer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-073086 A [Patent Document 2] Special Publication No. 2007-534810 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to provide pigment-containing polyester resin particles containing fewer coarse particles. [Means for solving the problem]

[0005] Specific means for solving the above problems include the following aspects. <1> A pigment-containing polyester resin particle containing a polyester resin and a pigment, the pigment is not exposed on the surface of the pigment-containing polyester resin particle and is not inscribed in the outline of the pigment-containing polyester resin particle; Pigment-containing polyester resin particles. <2> The volume average particle size is 50 nm or more and 500 nm or less. <1> 2. The pigment-containing polyester resin particles according to claim 1 . <3> The content of the pigment is 10% by mass or more and 60% by mass or less. <1> or <2> 2. The pigment-containing polyester resin particles according to claim 1 . <4> The average diameter of the pigment is 10 nm or more and 400 nm or less. <1> ~ <3> 2. The pigment-containing polyester resin particles according to claim 1 . <5> The acid value of the polyester resin is 1 mgKOH / g or more and 50 mgKOH / g or less. <1> ~ <4> 2. The pigment-containing polyester resin particles according to claim 1 . <6> <1> ~ <5> A method for producing the pigment-containing polyester resin particles according to any one of the above, mixing a polyester resin, a pigment, a basic compound, and a surfactant by applying heat and shear force to obtain a mixture in which the pigment is dispersed in the molten polyester resin; Adding an aqueous medium to the mixture while applying a shear force to emulsify the mixture. A method for producing pigment-containing polyester resin particles. <7> <1> ~ <5> A method for producing the pigment-containing polyester resin particles according to any one of the above, mixing a polyester resin, a pigment, and an organic solvent by applying heat and shear force to obtain a mixture in which the pigment is dispersed in the dissolved polyester resin; adding a basic compound to the mixture, and then adding an aqueous medium while applying a shear force to emulsify the mixture. A method for producing pigment-containing polyester resin particles. <8> <1> ~ <5> aggregating the pigment-containing polyester resin particles in a dispersion containing the pigment-containing polyester resin particles described in any one of the above to form aggregated particles; and heating the dispersion liquid containing the aggregated particles to fuse and coalesce the aggregated particles to form toner particles. A method for producing a toner for developing electrostatic images. <9> The toner particles include a polyester resin and a pigment, In the toner particles, the ratio of pigment particles having a maximum Feret diameter of 250 nm or more is 20% by number or less. Toner for developing electrostatic images. <10> <9> 2. An electrostatic image developer comprising the toner for developing electrostatic images according to claim 1. <11> <9> The toner for developing an electrostatic image according to claim 1 is contained in the container. A toner cartridge that is detachably attached to an image forming apparatus. <12> <10> and a developing unit which develops an electrostatic image formed on a surface of an image carrier into a toner image by using the electrostatic image developer, A process cartridge that is detachably attached to an image forming apparatus. <13> An image carrier; a charging means for charging the surface of the image carrier; an electrostatic image forming means for forming an electrostatic image on the charged surface of the image carrier; <10> a developing means for developing the electrostatic image formed on the surface of the image carrier into a toner image by using the electrostatic image developer; a transfer means for transferring the toner image formed on the surface of the image carrier to a surface of a recording medium; a fixing means for fixing the toner image transferred onto the surface of the recording medium; An image forming apparatus comprising: <14> a charging step of charging the surface of the image carrier; an electrostatic image forming step of forming an electrostatic image on the charged surface of the image carrier; <10> a developing step of developing the electrostatic image formed on the surface of the image carrier into a toner image by using the electrostatic image developer according to claim 1; a transfer step of transferring the toner image formed on the surface of the image carrier onto a surface of a recording medium; a fixing step of fixing the toner image transferred onto the surface of the recording medium; The image forming method according to claim 1, Effect of the Invention

[0006] <1> According to the present invention, pigment-containing polyester resin particles having fewer coarse particles are provided as compared with pigment-containing polyester resin particles in which the pigment is exposed on the surface of the pigment-containing polyester resin particle or in which the pigment is inscribed within the contour of the pigment-containing polyester resin particle. <2> According to the present invention, pigment-containing polyester resin particles having fewer coarse particles are provided as compared with pigment-containing polyester resin particles having a volume average particle size of less than 50 nm or more than 500 nm. <3> According to the present invention, pigment-containing polyester resin particles having a smaller amount of coarse particles are provided as compared with pigment-containing polyester resin particles having a pigment content of less than 10% by mass or more than 60% by mass. <4> According to the present invention, pigment-containing polyester resin particles are provided which have fewer coarse particles than pigment-containing polyester resin particles in which the average diameter of the pigment is less than 10 nm or more than 400 nm. <5> According to the present invention, pigment-containing polyester resin particles having fewer coarse particles are provided as compared with pigment-containing polyester resin particles having a polyester resin acid value of less than 1 mgKOH / g or more than 50 mgKOH / g. <6> According to the present invention, there is provided a method for producing pigment-containing polyester resin particles containing fewer coarse particles. <7> According to the present invention, there is provided a method for producing pigment-containing polyester resin particles containing fewer coarse particles. <8> According to the present invention, there is provided a method for producing a toner for developing electrostatic images which has excellent low-temperature fixing property and is less likely to cause image unevenness. <9> According to the present invention, there is provided a toner for developing electrostatic images which is excellent in low-temperature fixing property and which is less likely to cause image unevenness. <10> According to the present invention, there is provided an electrostatic image developer which has excellent low-temperature fixing property and is less likely to cause image unevenness. <11> According to the present invention, a toner cartridge is provided that contains a toner for developing electrostatic images that has excellent low-temperature fixing properties and is less likely to cause image unevenness. <12> According to the present invention, a process cartridge is provided that contains an electrostatic image developer that has excellent low-temperature fixing properties and is less likely to cause image unevenness. <13> According to the present invention, an image forming apparatus having excellent low-temperature fixing ability and less occurrence of image unevenness is provided. <14> According to the present invention, there is provided an image forming method which has excellent low-temperature fixing ability and is less susceptible to image unevenness. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic diagram illustrating an image forming apparatus according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a schematic diagram illustrating a process cartridge according to the present embodiment. [Diagram 3] FIG. 2 is a schematic diagram of an image formed for evaluating image quality in the examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments of the present disclosure will be described. These descriptions and examples are merely illustrative of the embodiments, and are not intended to limit the scope of the embodiments.

[0009] In the present disclosure, a numerical range indicated using "~" indicates a range that includes the numerical values ​​before and after "~" as the minimum and maximum values, respectively. In the numerical ranges described in the present disclosure in stages, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. In addition, in the numerical ranges described in the present disclosure, the upper or lower limit value of the numerical range may be replaced with a value shown in the examples.

[0010] In the present disclosure, the term "step" includes not only an independent step, but also a step that cannot be clearly distinguished from other steps as long as the purpose of the step is achieved.

[0011] When an embodiment of the present disclosure is described with reference to the drawings, the configuration of the embodiment is not limited to the configuration shown in the drawings. In addition, the size of the members in each drawing is conceptual, and the relative relationship between the sizes of the members is not limited to this.

[0012] In the present disclosure, each component may contain multiple types of corresponding substances. When referring to the amount of each component in a composition in the present disclosure, if multiple substances corresponding to each component are present in the composition, the total amount of the multiple substances present in the composition is meant unless otherwise specified. In the present disclosure, the particles corresponding to each component may include multiple types. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component means the value for a mixture of the multiple types of particles present in the composition, unless otherwise specified.

[0013] In the present disclosure, "(meth)acrylic" is an expression that includes both acrylic and methacrylic, and "(meth)acrylate" is an expression that includes both acrylate and methacrylate.

[0014] In this disclosure, "toner" refers to "toner for developing electrostatic images", "developer" refers to "electrostatic image developer", and "carrier" refers to "carrier for developing electrostatic images".

[0015] In the present disclosure, a method for producing toner particles by agglomerating and coalescing material particles in a dispersion medium is referred to as an EA (emulsion aggregation) method.

[0016] <Pigment-containing polyester resin particles> The pigment-containing polyester resin particles according to this embodiment contain a polyester resin and a pigment, and the pigment is not exposed on the surface of the pigment-containing polyester resin particle and is not inscribed within the contour of the pigment-containing polyester resin particle. That is, the pigment contained in the pigment-containing polyester resin particles is entirely coated with the polyester resin. Therefore, in the pigment-containing polyester resin particles according to this embodiment, the pigment particles are prevented from agglomerating with each other, and therefore the amount of coarse particles is small.

[0017] The state of the pigment contained in the pigment-containing polyester resin particles is confirmed by the following method. The pigment-containing polyester resin particles are mixed and embedded in an epoxy resin, and the epoxy resin is solidified. If the pigment-containing polyester resin particles are in the form of a dispersion, the dispersion is dried and the pigment-containing polyester resin particles are extracted. The solidified material is cut with an ultramicrotome (UltracutUCT, Leica) to prepare a thin slice sample with a thickness of 100 nm. The cross section of the thin slice sample is observed at a magnification of 10,000 times with a field emission scanning electron microscope (FE-SEM, model number: S-4800, Hitachi High-Technologies Corporation) to obtain an SEM image. The SEM image is imported into image analysis software ImageJ bundled with 32-bit Java 1.6.0_24ver ("Java" is a registered trademark), and noise in the image is removed by Despeckle processing in the Process menu, and then the image is analyzed and binarized under a brightness threshold of 50%, and the outline of the pigment particles present inside the pigment-containing polyester resin particles is extracted. It does not matter whether the pigment particles are primary particles or secondary particles. All resin particles and pigment particles within one field of view are observed, and the presence or absence of pigment particles protruding from the outer edge of the resin particles (i.e., exposed) and the presence or absence of pigment particles in contact with the outer edge of the resin particles (i.e., inscribed) are confirmed. The same procedure is repeated until at least 100 resin particles are observed. When the total number of resin particles in which the pigment particles protrude from the outer edge of the resin particle and the pigment particles in which the pigment particles are in contact with the outer edge of the resin particle is 5% or less of the total number of resin particles observed, it is determined that the pigment is not exposed on the surface of the pigment-containing polyester resin particle and is not inscribed in the contour of the pigment-containing polyester resin particle.

[0018] Conventionally, polyester resins and styrene-acrylic resins have been widely used as binder resins for toners, and in terms of low-temperature fixing properties of toners, polyester resins are generally superior to styrene-acrylic resins. By using the pigment-containing polyester resin particles according to this embodiment, the polyester resin can be used as the main binder resin of the toner, and a toner having excellent low-temperature fixing properties can be produced. Furthermore, by using the pigment-containing polyester resin particles according to this embodiment, the inclusion of coarse pigment agglomerates inside the toner particles is suppressed, and the produced toner is less likely to cause image unevenness.

[0019] The pigment-containing polyester resin particles according to this embodiment preferably have a volume average particle size of 50 nm or more and 500 nm or less. When the volume average particle diameter of the pigment-containing polyester resin particles is 50 nm or more, the pigment is less likely to be exposed, and therefore the pigment-containing polyester resin particles are less likely to become coarse powder. From this viewpoint, the volume average particle diameter of the pigment-containing polyester resin particles is more preferably 80 nm or more, and further preferably 100 nm or more. When the volume average particle diameter of the pigment-containing polyester resin particles is 500 nm or less, the pigment in the pigment-containing polyester resin particles is less likely to aggregate. From this viewpoint, the volume average particle diameter of the pigment-containing polyester resin particles is more preferably 400 nm or less, and further preferably 300 nm or less.

[0020] The volume average particle size of the pigment-containing polyester resin particles refers to the particle size that is 50% cumulative from the small diameter side in the particle size distribution measured by a laser diffraction particle size distribution analyzer (e.g., model number: LS13-320, Beckman Coulter). The number of particles measured is 10,000.

[0021] The pigment-containing polyester resin particles according to this embodiment preferably have a pigment content of 10% by mass or more and 60% by mass or less. A pigment content of 10% by mass or more is desirable for image-forming materials. From this viewpoint, the pigment content is more preferably 12% by mass or more, and even more preferably 15% by mass or more. When the pigment content is 60% by mass or less, the pigment is less likely to be exposed, and therefore the pigment-containing polyester resin particles are less likely to become coarse powder. From this viewpoint, the pigment content is more preferably 55% by mass or less, and further preferably 50% by mass or less.

[0022] In the pigment-containing polyester resin particles according to this embodiment, the average diameter of the pigment is preferably 10 nm or more and 400 nm or less. When the average diameter of the pigment is 10 nm or more, the pigment is less likely to aggregate. From this viewpoint, the average diameter of the pigment is more preferably 15 nm or more, and further preferably 20 nm or more. When the average diameter of the pigment is 400 nm or less, the pigment is less likely to be exposed, and therefore the pigment-containing polyester resin particles are less likely to become coarse powder. From this viewpoint, the average diameter of the pigment is more preferably 300 nm or less, and further preferably 200 nm or less.

[0023] The average diameter of the pigment contained in the pigment-containing polyester resin particles is determined by the following method. The pigment-containing polyester resin particles are mixed and embedded in an epoxy resin, and the epoxy resin is solidified. If the pigment-containing polyester resin particles are in the form of a dispersion, the dispersion is dried and the pigment-containing polyester resin particles are extracted. The solidified material is cut with an ultramicrotome (UltracutUCT, Leica) to prepare a thin slice sample with a thickness of 100 nm. The cross section of the thin slice sample is observed at a magnification of 10,000 times with a field emission scanning electron microscope (FE-SEM, model number: S-4800, Hitachi High-Technologies Corporation) to obtain an SEM image. The SEM image is imported into image analysis software ImageJ bundled with 32-bit Java 1.6.0_24ver ("Java" is a registered trademark), and noise in the image is removed by Despeckle processing in the Process menu, and then the image is analyzed and binarized under a brightness threshold of 50%, and the outline of the pigment particles present inside the pigment-containing polyester resin particles is extracted. It does not matter whether the pigment particles are primary particles or secondary particles. The circle equivalent diameter of the outline of all pigment particles within one field of view is measured. The same operation is repeated until at least 100 pigment particles are measured. The arithmetic average of the measured circle equivalent diameters is taken as the average diameter of the pigment.

[0024] [Pigment] Examples of pigments include organic pigments such as carbon black, chrome yellow, Hansa yellow, benzidine yellow, threne yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, Balkan orange, watch young red, permanent red, brilliant carmine 3B, brilliant carmine 6B, DuPont oil red, pyrazolone red, lithol red, rhodamine B lake, lake red C, pigment red, rose bengal, aniline blue, ultramarine blue, chalco oil blue, methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, and malachite green oxalate; and inorganic pigments such as titanium compounds and silica.

[0025] The pigments may be used alone or in combination of two or more kinds. The pigment may be surface-treated as necessary.

[0026] [Polyester resin] The polyester resin may be an amorphous polyester resin or a crystalline polyester resin. The polyester resin may be an amorphous polyester resin alone, a crystalline polyester resin alone, or a combination of an amorphous polyester resin and a crystalline polyester resin. The polyester resin is preferably an amorphous polyester resin.

[0027] The acid value of the polyester resin is preferably 1 mgKOH / g or more and 50 mgKOH / g or less. When the acid value of the polyester resin is 1 mgKOH / g or more, the viscosity of the resin composition during production of the pigment-containing polyester resin particles is not too low, and the pigment is easily incorporated into the pigment-containing polyester resin particles. From this viewpoint, the acid value of the polyester resin is more preferably 5 mgKOH or more, and further preferably 10 mgKOH or more. When the acid value of the polyester resin is 50 mgKOH / g or less, the viscosity of the resin composition during production of the pigment-containing polyester resin particles is not too high, and the pigment is easily incorporated into the pigment-containing polyester resin particles. From this viewpoint, the acid value of the polyester resin is more preferably 45 mgKOH or less, and even more preferably 40 mgKOH or less.

[0028] The acid value of the polyester resin is determined by the neutralization titration method specified in JIS K0070-1992 using an appropriate amount of polyester resin as a sample.

[0029] -Amorphous polyester resin- The amorphous polyester resin may be a commercially available product or a synthetic product. The amorphous polyester resin may be, for example, a condensation polymer of a polycarboxylic acid and a polyhydric alcohol.

[0030] Examples of polyvalent carboxylic acids that are polymerization components of amorphous polyester resins include aliphatic dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, sebacic acid, etc.), alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, etc.), anhydrides thereof, or lower alkyl esters thereof (e.g., having 1 to 5 carbon atoms). Among these, aromatic dicarboxylic acids are preferred as the polyvalent carboxylic acids. The polyvalent carboxylic acid may be a trivalent or higher carboxylic acid having a crosslinked or branched structure in combination with a dicarboxylic acid. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, anhydrides thereof, and lower (e.g., carbon number 1 to 5) alkyl esters thereof. The polyvalent carboxylic acids may be used alone or in combination of two or more kinds.

[0031] Examples of polyhydric alcohols that are polymerization components of amorphous polyester resins include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,1 Examples of the polyhydric alcohol include 1-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,14-eicosanedecanediol, alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, and hydrogenated bisphenol A), and aromatic diols (e.g., an ethylene oxide adduct of bisphenol A and a propylene oxide adduct of bisphenol A). Among these, the polyhydric alcohol is preferably an aliphatic diol. As the polyhydric alcohol which is a polymerization component of the amorphous polyester resin, a polyhydric alcohol having a crosslinked structure or a branched structure of trihydric or more may be used in combination with the diol. Examples of the polyhydric alcohol having trihydric or more include glycerin, trimethylolpropane, and pentaerythritol. The polyhydric alcohols may be used alone or in combination of two or more kinds.

[0032] The glass transition temperature (Tg) of the amorphous polyester resin is preferably 50°C or more and 75°C or less, more preferably 50°C or more and 70°C or less, and even more preferably 50°C or more and 65°C or less. The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), more specifically, from the "extrapolated glass transition onset temperature" described in the method for determining glass transition temperature in JIS K7121-1987 "Method for measuring transition temperature of plastics."

[0033] The weight average molecular weight (Mw) of the amorphous polyester resin is preferably 5,000 or more and 1,000,000 or less, and more preferably 7,000 or more and 500,000 or less. The number average molecular weight (Mn) of the amorphous polyester resin is preferably 2,000 or more and 100,000 or less. The molecular weight distribution Mw / Mn of the amorphous polyester resin is preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less. The weight average molecular weight and number average molecular weight are measured by gel permeation chromatography (GPC). The molecular weight measurement by GPC is performed using a Tosoh GPC HLC-8120GPC as the measuring device, a Tosoh TSKgel SuperHM-M (15 cm) column, and THF solvent. The weight average molecular weight and number average molecular weight are calculated from the measurement results using a molecular weight calibration curve created with a monodisperse polystyrene standard sample.

[0034] The amorphous polyester resin can be obtained by a known production method, for example, by carrying out the reaction while removing water and alcohol generated during condensation by setting the polymerization temperature to 180° C. or higher and 230° C. or lower, and reducing the pressure in the reaction system as necessary. If the raw material monomer is not soluble or compatible at the reaction temperature, a high boiling point solvent may be added as a solubilizing agent to dissolve it. In this case, the polycondensation reaction is carried out while distilling off the solubilizing agent. If a monomer with poor compatibility is present in the copolymerization reaction, it is recommended that the monomer with poor compatibility is condensed in advance with the acid or alcohol to be polycondensed, and then polycondensed with the main component.

[0035] -Crystalline polyester resin- The crystalline polyester resin may be a commercially available product or a synthetic product. Examples of the crystalline polyester resin include polycondensates of polyvalent carboxylic acids and polyhydric alcohols. The crystalline polyester resin is preferably a polycondensate of a linear aliphatic polymerizable monomer rather than a polymerizable monomer having an aromatic ring, since it easily forms a crystal structure.

[0036] Examples of polyvalent carboxylic acids that are polymerization components of crystalline polyester resins include aliphatic dicarboxylic acids (e.g., oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, etc.), anhydrides thereof, and lower (e.g., carbon number 1 to 5) alkyl esters thereof. The polyvalent carboxylic acid may be a trivalent or higher carboxylic acid having a crosslinked or branched structure in combination with a dicarboxylic acid. Examples of the trivalent carboxylic acid include aromatic carboxylic acids (e.g., 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, etc.), their anhydrides, and their lower (e.g., carbon number 1 to 5) alkyl esters. As the polyvalent carboxylic acid, a dicarboxylic acid having a sulfonic acid group and a dicarboxylic acid having an ethylenic double bond may be used in combination with these dicarboxylic acids. The polyvalent carboxylic acids may be used alone or in combination of two or more kinds.

[0037] Examples of polyhydric alcohols that are polymerization components of crystalline polyester resins include aliphatic diols (for example, straight-chain aliphatic diols having a main chain carbon number of 7 to 20). Examples of aliphatic diols include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,14-eicosanedecanediol. As the polyhydric alcohol which is a polymerization component of the crystalline polyester resin, a trihydric or higher alcohol having a crosslinked or branched structure may be used in combination with the diol. Examples of the trihydric or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol. The polyhydric alcohols may be used alone or in combination of two or more kinds.

[0038] The melting temperature of the crystalline polyester resin is preferably 50°C or higher and 100°C or lower, more preferably 55°C or higher and 90°C or lower, and even more preferably 60°C or higher and 85°C or lower. The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) based on the "peak melting temperature" as described in the method for determining melting temperature in JIS K7121-1987 "Method for measuring transition temperature of plastics."

[0039] The weight average molecular weight (Mw) of the crystalline polyester resin is preferably 6,000 or more and 35,000 or less.

[0040] The crystalline polyester resin can be obtained, for example, by a known production method, like the amorphous polyester.

[0041] <Method of producing pigment-containing polyester resin particles> The pigment-containing polyester resin particles are preferably produced in the form of a dispersion liquid containing the particles. That is, the process for producing the pigment-containing polyester resin particles is preferably a process for producing a pigment-containing polyester resin particle dispersion liquid. From the viewpoint of containing a sufficient amount of pigment in the toner particles, the solid content concentration of the pigment-containing polyester resin particle dispersion is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more. The solid content concentration of the pigment-containing polyester resin particle dispersion is preferably 40% by mass or less, more preferably 35% by mass or less, and even more preferably 30% by mass or less, from the viewpoint of particle dispersibility.

[0042] Specifically, the pigment-containing polyester resin particles are preferably produced by "solvent-free emulsification" or "solvent emulsification" described below. "Solvent-free emulsification" and "solvent emulsification" produce a pigment-containing polyester resin particle dispersion. In the "solventless emulsification" or "solvent emulsification", by controlling the operating conditions of the apparatus and / or the amount of materials used, it is possible to control the volume average particle size of the pigment-containing polyester resin particles, the pigment content, the average diameter of the pigment, and the like within preferred ranges while covering the entire periphery of the pigment with polyester resin.

[0043] [Solvent-free emulsion] Solvent-free emulsification is a method in which no organic solvent is used in producing a resin particle dispersion. Specifically, the solvent-free emulsification is The process includes the steps of mixing a polyester resin, a pigment, a basic compound, and a surfactant by applying heat and shear force to obtain a mixture in which the pigment is dispersed in the molten polyester resin (melting step), and emulsifying the mixture by adding an aqueous medium while applying shear force (emulsification step).

[0044] In the solventless emulsification, the melting step and the emulsification step are preferably carried out using a kneading extruder. The kneading extruder is a device that applies heat and shear force to the material to be treated while continuously conveying the material. The structure of the kneading extruder is generally roughly divided into a material inlet, a barrel, and a die from upstream to downstream. A screw is provided inside the barrel. A heater for heating the inside of the barrel is provided around the barrel. The screw may be a single-screw type or a twin-screw type, and the twin-screw type is preferable.

[0045] -Melting process- The melting step is a step in which the polyester resin, the pigment, the basic compound and the surfactant are mixed by applying heat and shear force to obtain a mixture in which the pigment is dispersed in the molten polyester resin.

[0046] As the basic compound, sodium hydroxide or potassium hydroxide is suitable. From the viewpoint of uniformity of kneading, sodium hydroxide or potassium hydroxide is preferably used in the form of an aqueous solution (i.e., an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution).

[0047] The amount of the basic compound used is an amount that can emulsify and disperse the mixture. Specifically, the amount of the basic compound used is preferably an amount that results in a neutralization rate of 20% or more and 60% or less according to the following formula (1). Formula (1): Neutralization rate (%) = mb×n×56.1÷Mwb÷AV×1000, mb is the amount (g) of basic compound used per 1 g of polyester resin, n is the valence of the basic compound, Mwb is the molecular weight of the basic compound, AV is the acid value of the polyester resin (mg KOH / g).

[0048] The surfactant may be any of anionic surfactants, cationic surfactants, and nonionic surfactants. Examples 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. The surfactants may be used alone or in combination of two or more. The nonionic surfactants may be used in combination with an anionic surfactant or a cationic surfactant. The amount of surfactant used is an amount that allows the emulsified particles to remain dispersed.

[0049] -Emulsification process- The emulsification step is a step in which an aqueous medium is added to a mixture in which the pigment is dispersed in the molten polyester resin while applying a shear force to the mixture, thereby emulsifying the mixture.

[0050] The aqueous medium is preferably water having a reduced ion content, such as distilled water or ion-exchanged water. The aqueous medium is preferably used with its temperature adjusted to within ±5° C. of the internal barrel temperature of the kneading extruder.

[0051] The temperature inside the barrel of the kneading extruder in the melting step is preferably 80°C or higher and 100°C or lower, more preferably 85°C or higher and 97°C or lower, and even more preferably 90°C or higher and 95°C or lower. The temperature inside the barrel of the kneading extruder in the emulsification step is preferably 80°C or higher and 100°C or lower, more preferably 85°C or higher and 97°C or lower, and even more preferably 90°C or higher and 95°C or lower.

[0052] [Solvent emulsification] Specifically, the solvent emulsification is The process includes the steps of mixing a polyester resin, a pigment, and an organic solvent by applying heat and shear force to obtain a mixture in which the pigment is dispersed in the dissolved polyester resin (dissolving step), and adding a basic compound to the mixture, and then adding an aqueous medium while applying shear force to emulsify the mixture (emulsifying step).

[0053] The solvent emulsification is preferably carried out in a stirring tank equipped with a stirring means and a heating / cooling means for the dissolving step and the emulsifying step. The stirring means is preferably a stirring means having a rotating shaft and a stirring blade. The heating / cooling means is preferably a means for applying and / or removing heat from the wall surface of the stirring tank.

[0054] -Dissolution process- The dissolving step is a step in which the polyester resin, the pigment, and the organic solvent are mixed by applying heat and shear force to obtain a mixture in which the pigment is dispersed in the dissolved polyester resin.

[0055] Examples of organic solvents in which polyester resins are soluble include ethyl acetate, isopropanol, 2-butanol, and mixed solvents thereof. Among these, organic solvents or mixed solvents having a boiling point of 60° C. or higher and lower than 100° C. are preferred.

[0056] -Emulsification process- The emulsification step is a step in which a basic compound is added to the mixture, and then an aqueous medium is added while applying a shear force, so that the mixture is emulsified and dispersed in the aqueous medium in the form of particles.

[0057] The basic compound is preferably ammonia water.

[0058] The amount of the basic compound used is an amount that can emulsify and disperse the mixture. Specifically, the amount of the basic compound used is preferably an amount that results in a neutralization rate of 70% or more and 100% or less according to the following formula (1). Formula (1): Neutralization rate (%) = mb×n×56.1÷Mwb÷AV×1000, mb is the amount (g) of basic compound used per 1 g of polyester resin, n is the valence of the basic compound, Mwb is the molecular weight of the basic compound, AV is the acid value of the polyester resin (mg KOH / g).

[0059] The aqueous medium is preferably water with a reduced ion content, such as distilled water or ion-exchanged water. The aqueous medium is preferably used at a temperature adjusted to a range of 35° C. to 100° C. (preferably 35° C. to 55° C.).

[0060] The temperature of the material to be treated contained in the stirring tank during the dissolving step is preferably 20°C or higher and 50°C or lower, more preferably 23°C or higher and 45°C or lower, and even more preferably 25°C or higher and 40°C or lower. The temperature of the material to be treated contained in the stirring tank during the emulsification step is preferably 20°C or higher and 50°C or lower, more preferably 23°C or higher and 45°C or lower, and even more preferably 25°C or higher and 40°C or lower.

[0061] The method of adding the aqueous medium in the emulsification step is preferably dropwise.

[0062] After the addition of the aqueous medium is completed, it is preferable to reduce the pressure inside the stirring tank and / or bubble the emulsion to remove the organic solvent. Thereafter, a surfactant may be added to improve the dispersion stability of the particles. Examples of the surfactant include the anionic surfactant, cationic surfactant, and nonionic surfactant described above.

[0063] <Method of manufacturing toner for developing electrostatic images> The toner production method according to this embodiment is a toner production method that includes producing toner particles by the EA method.

[0064] In the toner manufacturing method according to the present embodiment, at least pigment-containing polyester resin particles are used as material particles. Therefore, the method for producing the toner according to this embodiment includes aggregating and coalescing material particles including pigment-containing polyester resin particles in a dispersion medium to obtain toner particles.

[0065] Specifically, the method for producing the toner according to the present embodiment includes the following steps: aggregating the pigment-containing polyester resin particles in a dispersion liquid containing the pigment-containing polyester resin particles according to the present embodiment to form aggregated particles; heating the dispersion liquid containing the aggregated particles to fuse and coalesce the aggregated particles to form toner particles; has.

[0066] Hereinafter, each step and material of the EA method in this embodiment will be described in detail.

[0067] [Aggregation step (first aggregation step)] The aggregating step is a step of aggregating material particles in a dispersion liquid containing the material particles to form aggregated particles.

[0068] When the toner manufacturing method according to the present embodiment includes a second aggregation step (a step for forming a shell) described later, the above aggregation step is referred to as a "first aggregation step." The first aggregation step is a step for forming a core in a toner having a core-shell structure.

[0069] The dispersion liquid to be subjected to the aggregation step contains at least the pigment-containing polyester resin particles. The dispersion liquid to be subjected to the aggregation step preferably also contains the binder resin particles and the release agent particles.

[0070] The dispersion liquid to be subjected to the aggregation step is prepared, for example, by preparing a pigment-containing polyester resin particle dispersion liquid, a binder resin particle dispersion liquid, and a release agent particle dispersion liquid, and mixing these particle dispersion liquids. The order in which these particle dispersion liquids are mixed is not limited.

[0071] Hereinafter, the binder resin particle dispersion liquid and the release agent particle dispersion liquid will be collectively referred to as "particle dispersion liquid" to describe what they have in common.

[0072] An example of an embodiment of a particle dispersion liquid is a dispersion liquid in which a material is dispersed in the form of particles in a dispersion medium by a surfactant.

[0073] The dispersion medium of the particle dispersion liquid is preferably an aqueous medium. Examples of the aqueous medium include water and alcohol. The water is preferably water with a reduced ion content, such as distilled water or ion-exchanged water. These aqueous media may be used alone or in combination of two or more.

[0074] The surfactant for dispersing the material in the dispersion medium may be any of anionic surfactants, cationic surfactants, and nonionic surfactants. Examples of such 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. The surfactants may be used alone or in combination of two or more. The nonionic surfactants may be used in combination with an anionic surfactant or a cationic surfactant.

[0075] Methods for dispersing a material in a particulate form in a dispersion medium include known dispersion methods using a rotary shear type homogenizer, a ball mill having media, a sand mill, a dyno mill, and the like.

[0076] A method for dispersing a resin in a dispersion medium in the form of particles includes the phase inversion emulsification method. One example of the phase inversion emulsification method is a method in which a resin is dissolved in a hydrophobic organic solvent in which the resin is soluble, a basic compound is added to the organic continuous phase (O phase), and then an aqueous medium (W phase) is added to invert the phase from W / O to O / W, thereby dispersing the resin in the form of particles in the aqueous medium.

[0077] The volume average particle size of the particles dispersed in the particle dispersion is preferably 30 nm or more and 300 nm or less, more preferably 50 nm or more and 250 nm or less, and even more preferably 80 nm or more and 200 nm or less. The volume average particle size of particles in a particle dispersion refers to the particle size that is 50% cumulative from the smallest diameter side in the particle size distribution measured with a laser diffraction particle size distribution analyzer (e.g., model number: LS13-320, Beckman Coulter). The number of particles measured is 10,000.

[0078] The content of particles contained in the particle dispersion is preferably from 5% by mass to 50% by mass, more preferably from 10% by mass to 40% by mass, and even more preferably from 15% by mass to 30% by mass.

[0079] The materials constituting the particles of each of the binder resin particle dispersion liquid and the release agent particle dispersion liquid will be described below.

[0080] -Binding resin- Examples of the binder resin 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 (e.g., vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), and olefins (e.g., ethylene, propylene, butadiene, etc.), or 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 coexistence of these. These binder resins may be used alone or in combination of two or more kinds.

[0081] As the binder resin, a polyester resin is suitable. Examples of the polyester resin include an amorphous polyester resin and a crystalline polyester resin. As the polyester resin, only an amorphous polyester resin may be used, only a crystalline polyester resin may be used, or an amorphous polyester resin and a crystalline polyester resin may be used in combination.

[0082] When an amorphous polyester resin is used in producing the pigment-containing polyester resin particles, it is preferable that the binder resin contains an amorphous polyester resin having the same morphology as the amorphous polyester resin. When a crystalline polyester resin is used in the production of the pigment-containing polyester resin particles, it is preferable that the binder resin contains a crystalline polyester resin having the same form as the crystalline polyester resin.

[0083] -Release agent- Examples of the release agent include hydrocarbon waxes, natural waxes such as carnauba wax, rice wax, and candelilla wax, synthetic or mineral / petroleum waxes such as montan wax, and ester waxes such as fatty acid esters and montan acid esters. The release agent is not limited to these.

[0084] The melting temperature of the release agent is preferably 50°C or higher and 110°C or lower, and more preferably 60°C or higher and 100°C or lower. The melting temperature of the release agent is determined from a DSC curve obtained by differential scanning calorimetry (DSC) in accordance with the "melting peak temperature" described in the method for determining the melting temperature in JIS K7121:1987 "Method for measuring transition temperature of plastics."

[0085] Hereinafter, a dispersion obtained by mixing a plurality of types of particle dispersions will be referred to as a "mixed dispersion."

[0086] The mass ratio of the particles contained in the mixed dispersion is preferably in the following range. The mass ratio of the binder resin particles to the pigment-containing polyester resin particles (binder resin particles:pigment-containing polyester resin particles) is preferably 100:1 to 100:100, more preferably 100:2 to 100:60, and even more preferably 100:5 to 100:40. The mass ratio of the binder resin particles to the release agent particles is preferably 100:1 to 100:40, more preferably 100:2 to 100:30, and even more preferably 100:5 to 100:20.

[0087] After mixing the multiple types of particle dispersions, it is preferable to adjust the pH of the mixed dispersion to a range of 3 to 4. Examples of a means for adjusting the pH of the mixed dispersion include the addition of an acidic aqueous solution such as a nitric acid aqueous solution, a hydrochloric acid aqueous solution, or a sulfuric acid aqueous solution.

[0088] The aggregation step may, for example, be adding a flocculant to the mixed dispersion while stirring the mixed dispersion; After adding the flocculant to the mixed dispersion, the mixed dispersion is heated while being stirred to increase the temperature of the mixed dispersion.

[0089] Examples of the flocculant include a surfactant having a polarity opposite to that of the surfactant contained in the mixed dispersion, an inorganic metal salt, and a divalent or higher metal complex. The flocculant may be used alone or in combination of two or more kinds.

[0090] 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; and inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide.

[0091] The flocculant is preferably a divalent or higher metal salt compound, more preferably a trivalent metal salt compound, and even more preferably a trivalent inorganic aluminum salt compound, such as aluminum chloride, aluminum sulfate, polyaluminum chloride, and polyaluminum hydroxide.

[0092] The amount of the flocculant to be added is not limited. When a trivalent metal salt compound is used as the flocculant, the amount of the trivalent metal salt compound to be added is preferably 0.01 parts by mass or more and 10 parts by mass or less, more preferably 0.05 parts by mass or more and 5 parts by mass or less, and even more preferably 0.1 parts by mass or more and 3 parts by mass or less, relative to 100 parts by mass of the binder resin.

[0093] The temperature that the mixed dispersion reaches when it is heated is preferably a temperature based on the glass transition temperature (Tg) of the binder resin particles, for example, from (Tg-30°C) to (Tg°C) of the binder resin particles. When the mixed dispersion contains a plurality of types of binder resin particles having different Tg's, the lowest temperature among the Tg's is set as the Tg in the aggregation step.

[0094] [Second flocculation step] The second aggregation step is a step for the purpose of producing a toner having a core-shell structure, and is a step performed after the first aggregation step. The second aggregation step is a step for forming a shell.

[0095] The second aggregation step is a step of mixing a dispersion liquid containing aggregated particles with a dispersion liquid containing resin particles that will form the shell, and aggregating the resin particles that will form the shell onto the surfaces of the aggregated particles to form second aggregated particles.

[0096] As the dispersion liquid containing the resin particles that will become the shell, at least one selected from binder resin particle dispersion liquids for forming the core is suitable, a polyester resin particle dispersion liquid is more suitable, and an amorphous polyester resin particle dispersion liquid is even more suitable.

[0097] The second aggregation step may, for example, adding a dispersion liquid containing resin particles to be a shell to the dispersion liquid containing the aggregated particles while stirring the dispersion liquid containing the aggregated particles; and heating, while stirring, the dispersion liquid containing the aggregated particles after the dispersion liquid containing the resin particles that will become the shells has been added.

[0098] When the dispersion liquid containing the aggregated particles is heated, the temperature that the dispersion liquid containing the aggregated particles reaches is preferably a temperature based on the glass transition temperature (Tg) of the resin particles that form the shell, for example, a temperature not lower than (Tg-30°C) and not higher than (Tg-10°C) of the resin particles that form the shell.

[0099] After the aggregated particles or the second aggregated particles have grown to a predetermined size, a chelating agent for the aggregating agent used in the aggregation step may be added to the dispersion containing the aggregated particles or the second aggregated particles in order to stop the growth of the aggregated particles or the second aggregated particles before the heating in the coalescence step is performed. Examples of the chelating agent include oxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid; and aminocarboxylic acids such as iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA). The amount of the chelating agent added is 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, based on 100 parts by mass of the binder resin particles.

[0100] After the aggregated particles or the second aggregated particles have grown to a predetermined size, the pH of the dispersion containing the aggregated particles or the second aggregated particles may be increased in order to stop the growth of the aggregated particles or the second aggregated particles before the heating in the coalescence step is performed. The means for increasing the pH of the dispersion containing the aggregated particles or the second aggregated particles includes the addition of at least one selected from the group consisting of an aqueous solution of an alkali metal hydroxide and an aqueous solution of an alkaline earth metal hydroxide. The ultimate pH of the dispersion containing the aggregated particles or the second aggregated particles is preferably 8 or more and 10 or less.

[0101] [Uniting process] The coalescence step is a step in which the dispersion liquid containing the aggregated particles is heated to fuse and coalesce the aggregated particles to form toner particles.

[0102] When the second aggregation step is performed before the coalescence step, the coalescence step is a step in which the dispersion liquid containing the second aggregated particles is heated to fuse and coalesce the second aggregated particles to form toner particles. By performing the second aggregation step and the coalescence step, toner particles having a core-shell structure can be produced.

[0103] The form described below is common to the aggregated particles and the second aggregated particles.

[0104] The temperature reached by the dispersion liquid containing the aggregated particles is preferably equal to or higher than the glass transition temperature (Tg) of the binder resin, and specifically, is preferably 10° C. to 30° C. higher than the Tg of the binder resin. When the aggregated particles contain a plurality of binder resins having different Tg's, the highest temperature among the Tg's is defined as the glass transition temperature in the coalescence step.

[0105] After the coalescence step, the toner particles in the dispersion are subjected to a known washing step, solid-liquid separation step, and drying step to obtain dried toner particles. In the washing step, from the viewpoint of chargeability, it is preferable to carry out sufficient substitution washing with ion-exchanged water. In the solid-liquid separation step, it is preferable to carry out suction filtration, pressure filtration, etc., from the viewpoint of productivity. In the drying step, it is preferable to carry out freeze drying, air flow drying, fluidized drying, vibration type fluidized drying, etc., from the viewpoint of productivity.

[0106] [Step of adding external additives] The method for producing the toner according to the present embodiment preferably includes a step of externally adding an external additive to the toner particles. The external additive is added to the toner particles by mixing the toner particles in a dry state with the external additive. The mixing is performed, for example, by using a V blender, a Henschel mixer, a Loedige mixer, etc. Furthermore, if necessary, coarse particles of the toner may be removed using a vibration sieve, an air sieve, etc.

[0107] The external additive may be, for example, inorganic particles. Examples of inorganic particles include SiO 2 , TiO 2 , Al 2 O 3 , CuO, ZnO, SnO 2 , CEO 2 , Fe 2 O 3 , MgO, BaO, CaO, K 2 O, Na 2 O, ZrO 2 , CaO SiO 2 , K 2 O (TiO 2 ) n , Al 2 O 3 2SiO 2 , CaCO 3 , MgCO 3 , BaSO 4 , MgSO 4 etc.

[0108] The surface of the inorganic particles as an external additive may be subjected to hydrophobic treatment. The hydrophobic treatment may be performed, for example, by immersing the inorganic particles in a hydrophobic treatment agent. The hydrophobic treatment agent is not particularly limited, and examples thereof include silane coupling agents, silicone oils, titanate coupling agents, and aluminum coupling agents. These may be used alone or in combination of two or more. The amount of the hydrophobizing agent is usually, for example, 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the inorganic particles.

[0109] Examples of external additives include resin particles (resin particles such as polystyrene, polymethyl methacrylate, and melamine resin), cleaning agents (for example, metal salts of higher fatty acids such as zinc stearate, and fluorine-based polymer particles), and the like.

[0110] The amount of the external additive added is preferably from 0.01% by mass to 5% by mass, and more preferably from 0.01% by mass to 2% by mass, based on the mass of the toner particles.

[0111] <Toner for developing electrostatic images> The toner according to the present embodiment includes at least toner particles, and preferably includes toner particles and an external additive.

[0112] The toner according to the present embodiment includes toner particles containing a polyester resin and a pigment, and the percentage of pigment particles having a maximum Feret diameter of 250 nm or more in the toner particles is 20% by number or less. For pigments inside a toner particle, a maximum Feret diameter of 250 nm is an index of aggregation, and "pigments having a maximum Feret diameter of 250 nm or more" refers to undesirable aggregates. In the toner according to the present embodiment, the proportion of pigment particles having a maximum Feret diameter of 250 nm or more is 20% or less by number of the total number of pigment particles, and therefore the toner has excellent low-temperature fixing properties and is less susceptible to image unevenness. The percentage of pigments having a maximum Feret diameter of 250 nm or more is more preferably 15% by number or less, even more preferably 10% by number or less, and most preferably 0% by number.

[0113] The maximum Feret diameter of the pigment contained in the toner particles is measured by the following method. The toner is mixed and embedded in an epoxy resin, and the epoxy resin is solidified. The solidified product is cut using an ultramicrotome (UltracutUCT, Leica) to prepare a thin slice sample with a thickness of 100 nm. The cross section of the thin slice sample is observed at a magnification of 10,000 times using a field emission scanning electron microscope (FE-SEM, model number: S-4800, Hitachi High-Technologies Corporation) to obtain an SEM image. The SEM image is imported into image analysis software ImageJ bundled with 32-bit Java 1.6.0_24ver ("Java" is a registered trademark), and noise in the image is removed using the Despeckle process in the Process menu, after which analysis is performed under a brightness threshold of 50%, binarization is performed, and the contours of the pigment particles present in the toner particles are extracted. It does not matter whether the pigment particles are primary particles or secondary particles. The maximum Feret diameter is measured for the contours of all pigment particles present in the toner particles. The same operation is performed for 100 toner particles. The distribution of maximum Feret diameters is divided into 50 nm intervals in the range of 10 nm to 2000 nm, and the percentage of pigments with a maximum Feret diameter of 250 nm or more (number %) is calculated.

[0114] The total content of the polyester resin is preferably from 40% by mass to 95% by mass, more preferably from 50% by mass to 90% by mass, and even more preferably from 60% by mass to 85% by mass, based on the entire toner.

[0115] When the toner particles contain a crystalline polyester resin, the content of the crystalline polyester resin is preferably from 3% by mass to 30% by mass, and more preferably from 8% by mass to 20% by mass, of the total binder resin.

[0116] When the toner contains a release agent, the content of the release agent is preferably from 1% by mass to 20% by mass, and more preferably from 5% by mass to 15% by mass, based on the total mass of the toner.

[0117] The content of the pigment is preferably from 1% by mass to 30% by mass, and more preferably from 3% by mass to 15% by mass, based on the total mass of the toner.

[0118] The toner particles may be toner particles having a single layer structure, or may be toner particles having a so-called core-shell structure composed of a core portion (core particle) and a coating layer (shell layer) that coats the core portion.

[0119] The volume average particle size (D50v) of the toner particles is preferably from 2 μm to 10 μm, and more preferably from 4 μm to 8 μm.

[0120] The average particle size of toner particles is measured using a Coulter Multisizer II (manufactured by Beckman Coulter) and an ISOTON-II (manufactured by Beckman Coulter) as the electrolyte. 0.5 mg to 50 mg of the measurement sample is added to 2 ml of a 5% by mass aqueous solution of a surfactant (preferably sodium alkylbenzene sulfonate), and this is added to 100 ml to 150 ml of electrolyte. The electrolyte to which the sample has been added is dispersed for 1 minute using an ultrasonic disperser, and the particle size of the particles is measured in the range of 2 μm to 60 μm using an aperture with an aperture diameter of 100 μm using a Coulter Multisizer II. The number of particles measured is 50,000. Based on the measured particle size distribution, a volume distribution or number distribution is drawn from the small diameter side, and the particle size at which the cumulative 50% is reached is the volume average particle size D50v or number average particle size D50p.

[0121] 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.

[0122] The average circularity of a toner particle is the average of (circular equivalent perimeter) / (perimeter)=(perimeter of a circle having the same area as the projected area of ​​a particle) / (perimeter of a projected image of a particle). A flow type particle image analyzer (FPIA-3000 manufactured by Sysmex Corporation) is used as a particle image measuring device. The number of toner particles measured is 3500. When the toner has an external additive, the toner is dispersed in water containing a surfactant, and ultrasonic treatment is performed to obtain toner particles from which the external additive has been removed.

[0123] The external additive may be, for example, inorganic particles. Examples of inorganic particles include SiO 2 , TiO 2 , Al 2 O 3 , CuO, ZnO, SnO 2 , CEO 2 , Fe 2 O 3 , MgO, BaO, CaO, K 2 O, Na 2 O, ZrO 2 , CaO SiO 2 , K 2 O (TiO 2 ) n , Al 2 O 3 2SiO 2 , CaCO 3 , MgCO 3 , BaSO 4 , MgSO 4 etc.

[0124] The surface of the inorganic particles as an external additive is preferably subjected to hydrophobic treatment. The hydrophobic treatment is performed, for example, by immersing the inorganic particles in a hydrophobic treatment agent. The hydrophobic treatment agent is not particularly limited, and examples thereof include silane coupling agents, silicone oils, titanate coupling agents, and aluminum coupling agents. These may be used alone or in combination of two or more. The amount of the hydrophobic treatment agent is, for example, 1 part by mass or more and 10 parts by mass with respect to 100 parts by mass of the inorganic particles.

[0125] Examples of external additives include resin particles (resin particles such as polystyrene, polymethyl methacrylate, and melamine resin), cleaning agents (for example, metal salts of higher fatty acids such as zinc stearate, and fluorine-based polymer particles), and the like.

[0126] The amount of the external additive added is preferably from 0.01% by mass to 5% by mass, and more preferably from 0.01% by mass to 2% by mass, based on the toner particles.

[0127] <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 the present embodiment may be a one-component developer containing only the toner according to the present embodiment, or may be a two-component developer in which the toner is mixed with a carrier.

[0128] The carrier is not particularly limited, and may be any known carrier. Examples of the carrier include a coated carrier in which the surface of a core material made of magnetic powder is coated with a resin, a magnetic powder dispersion type carrier in which magnetic powder is dispersed and mixed in a matrix resin, and a resin impregnated type carrier in which porous magnetic powder is impregnated with a resin. The magnetic powder dispersion type carrier and the resin impregnated type carrier may be a carrier in which the constituent particles of the carrier are used as a core material, and the surface of the core material is coated with a resin.

[0129] Examples of the magnetic powder include magnetic metals such as iron, nickel, and cobalt; magnetic oxides such as ferrite and magnetite; and the like.

[0130] Examples of the resin and matrix resin for coating include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic acid ester copolymer, straight silicone resin or its modified product containing organosiloxane bonds, fluororesin, polyester, polycarbonate, phenolic resin, epoxy resin, etc. The resin and matrix resin for coating may contain other additives such as conductive particles. Examples of the conductive particles include particles of metals such as gold, silver, copper, carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, potassium titanate, etc.

[0131] To coat the surface of the core material with a resin, a method of coating with a coating layer forming solution in which the coating resin and various additives (used as necessary) are dissolved in a suitable solvent can be used. The solvent is not particularly limited and may be selected taking into consideration the type of resin used, suitability for application, etc. Specific resin coating methods include an immersion method in which the core material is immersed in a solution for forming a coating layer; a spray method in which the solution for forming a coating layer is sprayed onto the surface of the core material; a fluidized bed method in which the solution for forming a coating layer is sprayed onto the core material while it is suspended in flowing air; and a kneader coater method in which the carrier core material and the solution for forming a coating layer are mixed in a kneader coater and then the solvent is removed.

[0132] The mixture ratio (mass ratio) of the toner and the carrier in the two-component developer is preferably toner:carrier=1:100 to 30:100, and more preferably 3:100 to 20:100.

[0133] <Image forming apparatus and image forming method> An image forming apparatus and an image forming method according to the present embodiment will be described. The image forming apparatus according to the present embodiment includes an image carrier, a charging means for charging the surface of the image carrier, an electrostatic image forming means for forming an electrostatic image on the surface of the charged image carrier, a developing means for containing an electrostatic image developer and developing the electrostatic image formed on the surface of the image carrier as a toner image with the electrostatic image developer, a transfer means for transferring the toner image formed on the surface of the image carrier to the surface of a recording medium, and a fixing means for fixing the toner image transferred to the surface of the recording medium. The electrostatic image developer according to the present embodiment is used as the electrostatic image developer.

[0134] In the image forming apparatus according to this embodiment, an image forming method (the image forming method according to this embodiment) is carried out, which includes a charging step of charging the surface of an image carrier, an electrostatic image forming step of forming an electrostatic image on the surface of the charged image carrier, a developing step of developing the electrostatic image formed on the surface of the image carrier as a toner image using the electrostatic image developer according to this embodiment, a transfer step of transferring the toner image formed on the surface of the image carrier to the surface of a recording medium, and a fixing step of fixing the toner image transferred to the surface of the recording medium.

[0135] The image forming apparatus according to the present embodiment may be any of known image forming apparatuses, such as a direct transfer type apparatus in which a toner image formed on the surface of an image holder is directly transferred to a recording medium; an intermediate transfer type apparatus in which a toner image formed on the surface of an image holder is primarily transferred to the surface of an intermediate transfer body, and the toner image transferred to the surface of the intermediate transfer body is secondarily transferred to the surface of a recording medium; an apparatus equipped with a cleaning means for cleaning the surface of the image holder after the transfer of the toner image and before charging; and an apparatus equipped with a discharging means for irradiating the surface of the image holder with discharging light to discharge it after the transfer of the toner image and before charging it. When the image forming apparatus according to the present embodiment is an intermediate transfer type apparatus, the transfer means has, for example, an intermediate transfer body onto whose surface a toner image is transferred, a primary transfer means which primarily transfers the toner image formed on the surface of the image carrier onto the surface of the intermediate transfer body, and a secondary transfer means which secondarily transfers the toner image transferred onto the surface of the intermediate transfer body onto the surface of a recording medium.

[0136] In the image forming apparatus according to the present embodiment, for example, a portion including the developing means may have a cartridge structure (process cartridge) that is detachably attached to the image forming apparatus. As the process cartridge, for example, a process cartridge that contains the electrostatic charge image developer according to the present embodiment and has the developing means is preferably used.

[0137] An example of an image forming apparatus according to the present embodiment will be described below, but the present invention is not limited to this example. In the following description, the main parts shown in the drawings will be described, and the description of the rest will be omitted.

[0138] FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus according to the present embodiment. The image forming apparatus shown in Fig. 1 includes first to fourth image forming units 10Y, 10M, 10C, and 10K (image forming means) of an electrophotographic type that output images of each color of yellow (Y), magenta (M), cyan (C), and black (K) based on color-separated image data. These image forming units (hereinafter sometimes simply referred to as "units") 10Y, 10M, 10C, and 10K are arranged in parallel at predetermined distances from each other in the horizontal direction. These units 10Y, 10M, 10C, and 10K may be process cartridges that are detachably attached to the image forming apparatus.

[0139] Above each of the units 10Y, 10M, 10C, and 10K, an intermediate transfer belt (one example of an intermediate transfer body) 20 is provided, which extends through each unit. The intermediate transfer belt 20 is provided wrapped around a drive roll 22 and a support roll 24, and runs in a direction from the first unit 10Y toward the fourth unit 10K. A force is applied to the support roll 24 by a spring (not shown) or the like in a direction away from the drive roll 22, and tension is applied to the intermediate transfer belt 20 wrapped around them. An intermediate transfer body cleaning device 30 is provided on the image carrier side of the intermediate transfer belt 20, facing the drive roll 22. The developing devices (an example of developing means) 4Y, 4M, 4C, and 4K of the units 10Y, 10M, 10C, and 10K are supplied with yellow, magenta, cyan, and black toners contained in toner cartridges 8Y, 8M, 8C, and 8K, respectively.

[0140] Since the first to fourth units 10Y, 10M, 10C, and 10K have the same configuration and operation, the first unit 10Y that forms a yellow image and is disposed upstream in the direction in which the intermediate transfer belt travels will be described here as a representative.

[0141] The first unit 10Y has a photoconductor 1Y that acts as an image carrier. Around the photoconductor 1Y, a charging roll (an example of a charging means) 2Y that charges the surface of the photoconductor 1Y to a predetermined potential, an exposure device (an example of an electrostatic image forming means) 3 that exposes the charged surface to a laser beam 3Y based on a color-separated image signal to form an electrostatic image, a developing device (an example of a developing means) 4Y that supplies charged toner to the electrostatic image to develop it, a primary transfer roll 5Y (an example of a primary transfer means) that transfers the developed toner image onto an intermediate transfer belt 20, and a photoconductor cleaning device (an example of a cleaning means) 6Y that removes toner remaining on the surface of the photoconductor 1Y after the primary transfer are arranged in this order. The primary transfer roll 5Y is disposed inside the intermediate transfer belt 20, and is provided at a position facing the photoconductor 1Y. A bias power supply (not shown) that applies a primary transfer bias is connected to the primary transfer rolls 5Y, 5M, 5C, and 5K of each unit. Each bias power supply changes the value of the transfer bias applied to each primary transfer roll under the control of a control unit (not shown).

[0142] Hereinafter, the operation of forming a yellow image in the first unit 10Y will be described. First, prior to operation, the surface of the photoconductor 1Y is charged to a potential of −600V to −800V by the charging roll 2Y. The photoconductor 1Y has a conductivity (for example, a volume resistivity of 1×10 at 20° C. -6The photosensitive layer is formed by laminating a photosensitive layer on a substrate having a resistivity of Ωcm or less. This photosensitive layer is usually highly resistive (the resistance of ordinary resins), but when irradiated with a laser beam, the resistivity of the portion irradiated with the laser beam changes. Therefore, the exposed surface of the charged photoreceptor 1Y is irradiated with a laser beam 3Y from the exposure device 3 in accordance with image data for yellow sent from a control unit (not shown). As a result, an electrostatic charge image of a yellow image pattern is formed on the surface of the photoreceptor 1Y.

[0143] An electrostatic image is an image formed on the surface of the photoconductor 1Y by electrostatic charging. The laser beam 3Y reduces the resistivity of the irradiated parts of the photosensitive layer, causing the charged charges on the surface of the photoconductor 1Y to flow, while the charges remain in the parts not irradiated by the laser beam 3Y. This is a so-called negative latent image. The electrostatic image formed on the photoconductor 1Y rotates to a predetermined developing position as the photoconductor 1Y travels. At this developing position, the electrostatic image on the photoconductor 1Y is developed into a toner image by the developing device 4Y and made visible.

[0144] The developing device 4Y contains an electrostatic image developer including at least yellow toner and a carrier, for example. The yellow toner is triboelectrically charged by being stirred inside the developing device 4Y, and is held on a developer roll (an example of a developer holder) with a charge of the same polarity (negative polarity) as the charge on the photoconductor 1Y. As the surface of the photoconductor 1Y passes through the developing device 4Y, the yellow toner electrostatically adheres to the discharged latent image portion on the surface of the photoconductor 1Y, and the latent image is developed with the yellow toner. The photoconductor 1Y on which the yellow toner image has been formed continues to travel at a predetermined speed, and the toner image developed on the photoconductor 1Y is transported to a predetermined primary transfer position.

[0145] When the yellow toner image on the photoreceptor 1Y is transported to the primary transfer position, a primary transfer bias is applied to the primary transfer roll 5Y, and an electrostatic force from the photoreceptor 1Y toward the primary transfer roll 5Y acts on the toner image, and the toner image on the photoreceptor 1Y is transferred onto the intermediate transfer belt 20. The transfer bias applied at this time has a polarity (+) opposite to the polarity (-) of the toner, and is controlled to, for example, +10 μA by a control unit (not shown) in the first unit 10Y. On the other hand, the toner remaining on the photoconductor 1Y is removed and collected by the photoconductor cleaning device 6Y.

[0146] The primary transfer bias applied to the primary transfer rolls 5M, 5C, and 5K subsequent to the second unit 10M is also controlled in accordance with the first unit. In this manner, the intermediate transfer belt 20 onto which the yellow toner image has been transferred by the first unit 10Y is conveyed successively through the second to fourth units 10M, 10C, and 10K, where the toner images of each color are transferred and superimposed.

[0147] The intermediate transfer belt 20 onto which the four color toner images have been transferred in multiple layers through the first to fourth units reaches a secondary transfer section that is composed of the intermediate transfer belt 20, a support roll 24 that contacts the inner surface of the intermediate transfer belt, and a secondary transfer roll (an example of a secondary transfer means) 26 arranged on the image bearing surface side of the intermediate transfer belt 20. Meanwhile, a recording paper (an example of a recording medium) P is fed at a predetermined timing into the gap between the secondary transfer roll 26 and the intermediate transfer belt 20 via a supply mechanism, and a secondary transfer bias is applied to the support roll 24. The transfer bias applied at this time has a (-) polarity that is the same as the (-) polarity of the toner, and an electrostatic force from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, and the toner image on the intermediate transfer belt 20 is transferred onto the recording paper P. The secondary transfer bias at this time is determined according to the resistance detected by a resistance detection means (not shown) that detects the resistance of the secondary transfer section, and is voltage-controlled.

[0148] Thereafter, the recording paper P is sent to a pressure contact portion (nip portion) of a pair of fixing rolls in a fixing device (one example of a fixing means) 28, where the toner image is fixed onto the recording paper P, forming a fixed image.

[0149] The recording paper P onto which the toner image is transferred can be, for example, plain paper used in electrophotographic copying machines, printers, etc. In addition to the recording paper P, other examples of the recording medium include overhead projector sheets and the like. To further improve the smoothness of the image surface after fixing, it is preferable that the surface of the recording paper P is also smooth. For example, coated paper in which the surface of ordinary paper is coated with a resin or the like, art paper for printing, etc. are preferably used.

[0150] After the color image has been fixed, the recording paper P is conveyed toward the discharge section, and the series of color image forming operations is completed.

[0151] <Process cartridge / toner cartridge> The process cartridge according to this embodiment will be described. The process cartridge according to this embodiment is a process cartridge that contains the electrostatic image developer according to this embodiment, is equipped with a developing means that develops an electrostatic image formed on the surface of an image carrier using the electrostatic image developer into a toner image, and is detachably attached to an image forming apparatus.

[0152] The process cartridge according to this embodiment is not limited to the above configuration, and may be configured to include a developing means and, as necessary, at least one other means selected from an image carrier, a charging means, an electrostatic image forming means, and a transfer means.

[0153] An example of a process cartridge according to the present embodiment will be described below, but the present invention is not limited to this example. In the following description, the main parts shown in the drawings will be described, and the description of the rest will be omitted.

[0154] FIG. 2 is a schematic diagram showing the process cartridge according to the present embodiment. The process cartridge 200 shown in FIG. 2 is configured by, for example, a housing 117 having a mounting rail 116 and an opening 118 for exposure, and integrally combining and holding a photoconductor 107 (an example of an image carrier), a charging roll 108 (an example of a charging means) provided around the photoconductor 107, a developing device 111 (an example of a developing means), and a photoconductor cleaning device 113 (an example of a cleaning means), which are assembled into a cartridge. In FIG. 2, 109 indicates an exposure device (an example of an electrostatic image forming means), 112 indicates a transfer device (an example of a transfer means), 115 indicates a fixing device (an example of a fixing means), and 300 indicates a recording paper (an example of a recording medium).

[0155] Next, the toner cartridge according to this embodiment will be described. The toner cartridge according to the present embodiment is a toner cartridge that contains the toner according to the present embodiment and is detachably attached to an image forming apparatus. The toner cartridge contains replenishment toner to be supplied to a developing unit provided in the image forming apparatus.

[0156] 1 is an image forming apparatus having a configuration in which toner cartridges 8Y, 8M, 8C, and 8K are detachably attached, and developing devices 4Y, 4M, 4C, and 4K are connected to toner cartridges corresponding to the respective developing devices (colors) by toner supply pipes (not shown). When the toner contained in a toner cartridge becomes low, the toner cartridge is replaced. EXAMPLES

[0157] Hereinafter, the embodiments of the present invention will be described in detail with reference to examples, but the embodiments of the present invention are not limited to these examples. In the following description, unless otherwise specified, "parts" and "%" are by mass. In the following description, unless otherwise specified, synthesis, production, processing, measurement, etc. were carried out at room temperature (25° C.±3° C.).

[0158] <Preparation of amorphous polyester resin> [Preparation of amorphous polyester resin (A)] The following materials were prepared: Terephthalic acid: 30 parts by mole Fumaric acid: 70 parts by mole Bisphenol A ethylene oxide adduct: 5 mole parts Bisphenol A propylene oxide adduct: 95 parts by mole

[0159] The above materials were charged into a flask equipped with a stirrer, a nitrogen inlet tube, a temperature sensor, and a distillation column, and the temperature of the reaction solution was raised to 220°C over 1 hour, and 1 part of titanium tetraethoxide was added for 100 parts of the above materials. The temperature of the reaction solution was raised to 230°C over 30 minutes while distilling off the generated water, and the dehydration condensation reaction was continued for 1 hour while maintaining the temperature of the reaction solution at 230°C. The temperature of the reactant was then cooled to room temperature. In this way, an amorphous polyester resin (A) with an acid value of 15.0 mgKOH / g, a weight average molecular weight of 18000, and a glass transition temperature of 60°C was obtained.

[0160] [Preparation of amorphous polyester resin (B)] The following materials were prepared: Terephthalic acid: 25 parts by mole Fumaric acid: 75 parts by mole Bisphenol A ethylene oxide adduct: 5 mole parts Bisphenol A propylene oxide adduct: 95 parts by mole

[0161] The above materials were charged into a flask equipped with a stirrer, a nitrogen inlet tube, a temperature sensor, and a distillation column, and the temperature of the reaction solution was raised to 220°C over 1 hour, and 1 part of titanium tetraethoxide was added for 100 parts of the above materials. The temperature of the reaction solution was raised to 230°C over 30 minutes while distilling off the generated water, and the dehydration condensation reaction was continued for 1 hour while maintaining the temperature of the reaction solution at 230°C. The temperature of the reactant was then cooled to room temperature. In this way, an amorphous polyester resin (B) with an acid value of 0.5 mg KOH / g, a weight average molecular weight of 18000, and a glass transition temperature of 60°C was obtained.

[0162] [Preparation of amorphous polyester resin (C)] The following materials were prepared: Terephthalic acid: 27 parts by mole Fumaric acid: 73 parts by mole Bisphenol A ethylene oxide adduct: 5 mole parts Bisphenol A propylene oxide adduct: 95 parts by mole

[0163] The above materials were charged into a flask equipped with a stirrer, a nitrogen inlet tube, a temperature sensor, and a distillation column, and the temperature of the reaction solution was raised to 220°C over 1 hour, and 1 part of titanium tetraethoxide was added for 100 parts of the above materials. The temperature of the reaction solution was raised to 230°C over 30 minutes while distilling off the generated water, and the dehydration condensation reaction was continued for 1 hour while maintaining the temperature of the reaction solution at 230°C. The temperature of the reactant was then cooled to room temperature. In this way, an amorphous polyester resin (C) with an acid value of 1.0 mgKOH / g, a weight average molecular weight of 18000, and a glass transition temperature of 60°C was obtained.

[0164] [Preparation of amorphous polyester resin (D)] The following materials were prepared: Terephthalic acid: 37.5 parts by mole Fumaric acid: 62.5 mol parts Bisphenol A ethylene oxide adduct: 5 mole parts Bisphenol A propylene oxide adduct: 95 parts by mole

[0165] The above materials were charged into a flask equipped with a stirrer, a nitrogen inlet tube, a temperature sensor, and a distillation column, and the temperature of the reaction solution was raised to 220°C over 1 hour, and 1 part of titanium tetraethoxide was added for 100 parts of the above materials. The temperature of the reaction solution was raised to 230°C over 30 minutes while distilling off the generated water, and the dehydration condensation reaction was continued for 1 hour while maintaining the temperature of the reaction solution at 230°C. The temperature of the reactant was then cooled to room temperature. In this way, an amorphous polyester resin (D) with an acid value of 50.0 mgKOH / g, a weight average molecular weight of 18000, and a glass transition temperature of 60°C was obtained.

[0166] [Preparation of amorphous polyester resin (E)] The following materials were prepared: Terephthalic acid: 42 parts by mole Fumaric acid: 58 mol parts Bisphenol A ethylene oxide adduct: 5 mole parts Bisphenol A propylene oxide adduct: 95 parts by mole

[0167] The above materials were charged into a flask equipped with a stirrer, a nitrogen inlet tube, a temperature sensor, and a distillation column, and the temperature of the reaction solution was raised to 220°C over 1 hour, and 1 part of titanium tetraethoxide was added for 100 parts of the above materials. The temperature of the reaction solution was raised to 230°C over 30 minutes while distilling off the generated water, and the dehydration condensation reaction was continued for 1 hour while maintaining the temperature of the reaction solution at 230°C. The temperature of the reactant was then cooled to room temperature. In this way, an amorphous polyester resin (E) with an acid value of 70.0 mgKOH / g, a weight average molecular weight of 18000, and a glass transition temperature of 60°C was obtained.

[0168] <Preparation of Pigment-Containing Polyester Resin Particle Dispersion> [Preparation of pigment-containing polyester resin particle dispersion (P1)] The following materials were prepared: Amorphous polyester resin (A): 160 parts Carbon black (Regal 330, Cabot Corporation): 40 parts Basic compound: 50% sodium hydroxide solution: 0.2 parts Surfactant: 48.5% sodium dodecyl diphenyl ether disulfonate aqueous solution (product name: Eleminol MON-7, Sanyo Chemical Industries, Ltd.): 4.1 parts Ion-exchanged water (1): 150 parts of ion-exchanged water at 90°C Ion-exchanged water (2): 150 parts of ion-exchanged water at 90°C Ion-exchanged water (3): 150 parts of ion-exchanged water at 90°C

[0169] A twin-screw kneading extruder (model number: TEM26SS, Toshiba Machine Co., Ltd.) was prepared. The barrel of the twin-screw kneading extruder used in this example was formed by connecting a plurality of barrel blocks.

[0170] -Mixing process- The barrel temperature of the twin-screw kneading extruder was set to 95°C, and the screw rotation speed was set to 400 rpm. The amorphous polyester resin (A) and carbon black were fed into the raw material inlet of the twin-screw kneading extruder, kneaded, and the treated material was once discharged. The treated material and a 50% aqueous sodium hydroxide solution were fed into the raw material inlet of the twin-screw kneading extruder, and a surfactant was fed from the barrel of the fourth block. All of the materials were kneaded and mixed to form a mixture containing a polyester resin, a pigment, a basic compound, and a surfactant.

[0171] -Emulsification process- Further, while operating the twin-screw kneading extruder so that the average feed rate of the mixture was 12 kg / h, ion-exchanged water (1) was fed from the barrel of the 5th block, ion-exchanged water (2) was fed from the barrel of the 7th block, and ion-exchanged water (3) was fed from the barrel of the 9th block, and the mixture was emulsified to obtain a pigment-containing polyester resin particle dispersion (P1). The solid content concentration of the pigment-containing polyester resin particle dispersion (P1) was 25%.

[0172] The particle size distribution of the particles in the pigment-containing polyester resin particle dispersion (P1) was measured using a laser diffraction particle size distribution analyzer (model number: LS13-320, Beckman Coulter). The volume average particle size of the particles in the pigment-containing polyester resin particle dispersion (P1) was 200 nm.

[0173] [Preparation of pigment-containing polyester resin particle dispersions (P2) to (P10), (P12) to (P16)] Each pigment-containing polyester resin particle dispersion was prepared in the same manner as in the preparation of the pigment-containing polyester resin particle dispersion (P1), except that the operating conditions of the twin-screw kneading extruder or the type of amorphous polyester resin were changed as shown in Table 1, and the amount of carbon black used was adjusted as necessary.

[0174] [Preparation of pigment-containing polyester resin particle dispersion (P11)] The following materials were prepared: Organic solvent (1): Ethyl acetate: 40 parts Organic solvent (2): 2-butanol: 25 parts Amorphous polyester resin (A): 160 parts Carbon black (Regal 330, Cabot Corporation): 40 parts Basic compound: 10% ammonia water: equivalent to 3 times the acid value of polyester resin in molar ratio Ion-exchanged water (4): 400 parts of ion-exchanged water at 40°C Surfactant: 48.5% sodium dodecyl diphenyl ether disulfonate aqueous solution (product name: Eleminol MON-7, Sanyo Chemical Industries, Ltd.): 1.0 part

[0175] -Dissolution process- Organic solvent (1) and organic solvent (2) were charged into a stirring tank equipped with a stirrer, a condenser, a heater, and a thermometer to prepare a mixed solvent. While maintaining the temperature in the stirring tank at 40°C and stirring, amorphous polyester resin (A) was charged and dissolved, and carbon black was gradually charged and dispersed.

[0176] -Emulsification process- While maintaining the temperature in the stirring tank and continuing the stirring, the basic compound was added and stirred for 30 minutes. The inside of the stirring tank was replaced with dry nitrogen, and while maintaining the temperature at 40°C and stirring, ion-exchanged water (4) was added dropwise at a rate of 2 parts / min to emulsify the contents. After the dropwise addition, the heating of the stirring tank was stopped, the temperature of the emulsion was lowered to room temperature, and then the emulsion was bubbled with dry nitrogen for 48 hours to remove the organic solvent from the emulsion. Next, a surfactant was added, and ion-exchanged water was added to adjust the solid concentration to 25%, to obtain an amorphous polyester resin particle dispersion (P11). The volume average particle size of the particles in the amorphous polyester resin particle dispersion (P11) was 200 nm.

[0177] <Preparation of pigment-containing styrene acrylic resin particle dispersion (SA1)> The following materials were prepared: Ion-exchanged water: 300 parts Sodium dodecylbenzenesulfonate: 3 parts Styrene: 60 parts 2-Ethylhexyl methacrylate: 15 parts Ethylene glycol dimethacrylate: 5 parts Polymerization initiator: t-butylperoxy-2-ethylhexanoate: 1 part

[0178] Ion-exchanged water and sodium dodecylbenzenesulfonate were added to a stirring tank and mixed with stirring. The above-mentioned monomer and polymerization initiator were added thereto and mixed with stirring to obtain a monomer solution.

[0179] The following materials were prepared: Ion-exchanged water: 180 parts Sodium dodecylbenzenesulfonate: 1.8 parts Carbon black (Regal 330, Cabot Corporation): 20 parts

[0180] Ion-exchanged water and sodium dodecylbenzenesulfonate were charged into a bead mill and mixed, after which carbon black was further charged and a dispersion treatment was carried out to obtain a pigment dispersion liquid.

[0181] The monomer solution and pigment dispersion were placed in a stirring tank and stirred at 30°C for 20 minutes, then the temperature was raised to 90°C and held for 3 hours with stirring. The liquid was then cooled to room temperature, and the solid matter was filtered off and thoroughly washed with ion-exchanged water. The washed solid matter was dispersed in ion-exchanged water containing a surfactant (sodium dodecyl diphenyl ether disulfonate) to obtain a pigment-containing styrene acrylic resin particle dispersion (SA1) with a solid content concentration of 25%. The volume average particle size of the particles in the pigment-containing styrene acrylic resin particle dispersion (SA1) was 200 nm.

[0182] <Preparation of amorphous polyester resin particle dispersion (1)> The following materials were prepared: Terephthalic acid: 30 parts by mole Fumaric acid: 70 parts by mole Bisphenol A ethylene oxide adduct: 5 mole parts Bisphenol A propylene oxide adduct: 95 parts by mole

[0183] The above materials were charged into a flask equipped with a stirrer, a nitrogen inlet tube, a temperature sensor, and a distillation column, and the temperature of the reaction solution was raised to 220°C over 1 hour, and 1 part of titanium tetraethoxide was added for 100 parts of the above materials. The temperature of the reaction solution was raised to 230°C over 30 minutes while distilling off the generated water, and the dehydration condensation reaction was continued for 1 hour while maintaining the temperature of the reaction solution at 230°C. The temperature of the reactant was then cooled to room temperature. In this way, an amorphous polyester resin with a weight average molecular weight of 18,000 and a glass transition temperature of 60°C was obtained.

[0184] A mixed solvent was prepared by adding 40 parts of ethyl acetate and 25 parts of 2-butanol to a vessel equipped with a temperature control means and a nitrogen replacement means. 100 parts of amorphous polyester resin was gradually added to the mixed solvent and dissolved, and 10% aqueous ammonia solution (equivalent to three times the amount by molar ratio relative to the acid value of the resin) was added and stirred for 30 minutes. Next, the inside of the vessel was replaced with dry nitrogen, the temperature of the reaction liquid was kept at 40°C, and 400 parts of ion-exchanged water was dropped at a rate of 2 parts / min while stirring the reaction liquid, and emulsified. After the drop of ion-exchanged water was completed, the temperature of the emulsion was cooled to room temperature, and dry nitrogen was bubbled for 48 hours while stirring the emulsion, reducing the total amount of ethyl acetate and 2-butanol to 1000 ppm or less. Ion-exchanged water was added to the emulsion to adjust the solid content concentration to 20%. In this way, an amorphous polyester resin particle dispersion (1) was obtained. The volume average particle size of the particles in the amorphous polyester resin particle dispersion (1) was 180 nm.

[0185] <Preparation of release agent particle dispersion (1)> The following materials were prepared: Paraffin wax (HNP-9, Nippon Seiro Co., Ltd.): 100 parts Ion-exchanged water: 350 parts Anionic surfactant (product name: Neogen RK, Daiichi Kogyo Seiyaku Co., Ltd., 20% aqueous solution): 1 part

[0186] The above materials were mixed and heated to 100°C, and dispersed using a homogenizer (Ultra Turrax T50, IKA), and then dispersed using a pressure discharge type homogenizer (Manton-Gaulin high pressure homogenizer, Gaulin). When the volume average particle size reached 200 nm, the particles were collected to obtain a release agent particle dispersion (1) with a solid content of 20%.

[0187] <Example 1> [Production of toner particles] The following materials were prepared: - Ion-exchanged water: 200 parts Amorphous polyester resin particle dispersion (1): 80 parts Pigment-containing polyester resin particle dispersion (P1): 3.7 parts Release agent particle dispersion (1): 8.0 parts Anionic surfactant (product name: Neogen RK, Daiichi Kogyo Seiyaku Co., Ltd., 20% aqueous solution): 1.1 parts

[0188] -First flocculation process- The above materials were placed in a round stainless steel flask, 0.1N nitric acid was added to adjust the pH to 3.5, and 30 parts of an aqueous nitric acid solution with a polyaluminum chloride concentration of 10% was added. The liquid temperature was adjusted to 30°C using an oil bath, and a dispersion treatment was performed using a homogenizer (product name: Ultra Turrax T50, IKA Corporation). Next, the liquid temperature was raised to 45°C and maintained for 30 minutes to form first aggregated particles.

[0189] -Second coagulation process- While maintaining the temperature of the dispersion containing the first aggregated particles at 45° C., 20 parts of the amorphous polyester resin particle dispersion (1) was added and held for 60 minutes to form second aggregated particles.

[0190] -Combining process- A 0.1N aqueous solution of sodium hydroxide was added to the dispersion liquid containing the second aggregated particles to adjust the pH to 8.5, and the liquid temperature was raised to 84°C and maintained for 150 minutes. The liquid was then cooled to 20°C at a rate of 20°C / min, and the solid matter was filtered off, washed with ion-exchanged water, and dried. The dried matter was sieved to obtain toner particles (1). The volume average particle size of the toner particles (1) was 6.0 μm.

[0191] [Manufacturing of toner with additives] To 100 parts of toner particles (1), 1.5 parts of hydrophobic silica particles (product number: RY50, Nippon Aerosil Co., Ltd.) and 1.0 part of hydrophobic titanium oxide (product number: T805, Nippon Aerosil Co., Ltd.) were added and mixed for 30 seconds at 10,000 rpm using a sample mill. The mixture was then sieved using a vibrating sieve with 45 μm openings to obtain an externally added toner.

[0192] [Manufacturing of developer] 8 parts of the toner with external additives and 92 parts of the following carrier (1) were placed in a V-blender and stirred for 20 minutes, after which the mixture was sieved through a sieve with 212 μm openings to obtain a developer.

[0193] -Manufacture of carrier (1)- 14 parts of toluene, 5 parts of polymethyl methacrylate (weight average molecular weight 75000), and 0.2 parts of carbon black (product number: VXC-72, Cabot Corporation) were placed in a sand mill and dispersed to prepare a dispersion liquid. The dispersion liquid and 100 parts of ferrite particles (average particle size 35 μm) were placed in a vacuum degassing kneader, and the mixture was dried under reduced pressure while stirring to obtain a carrier (1).

[0194] <Examples 2 to 15, Comparative Examples 1 to 2> In the same manner as in Example 1, except that the type of pigment-containing resin particle dispersion was changed as shown in Table 1, each toner particle, toner with external additives, and developer were prepared.

[0195] <Performance evaluation> [Ratio of coarse particles] Using a standard sieve with 20 μm openings, the pigment-containing polyester resin particle dispersions (P1) to (P16) and the pigment-containing styrene acrylic resin particle dispersion (SA1) were sieved, each equivalent to 100 g of solid content. The mass percentage of the solid content that did not pass through the sieve was classified as follows. G1 to G3 are within the acceptable range. G1: Less than 0.5% G1.5: 0.5% or more, less than 1% G2: 1% or more, less than 1.5% G2.5: 1.5% or more, less than 2% G3: 2% or more, less than 5% G4: 5% or more

[0196] [Low temperature fixability] The following operations and image formation were carried out in an environment at a temperature of 28° C. and a relative humidity of 85%. As recording paper, Premier TCF (grammage 80 g / m 2 The paper used was a paper with a relatively rough surface, which makes it difficult to uniformly transfer heat to the toner on the paper, and therefore makes it relatively difficult to fix the toner at a low temperature. The developer was filled into the developing unit of a modified image forming apparatus ApeosPort-V C7775 (FUJIFILM Business Innovation Co., Ltd.). The temperature of the fixing unit was set to 140°C, and the amount of toner applied to the paper was 1.0 mg / cm. 2 It was decided. A black solid image with an image density of 100% and a black halftone image with an image density of 30% were formed at the leading edge and trailing edge of the paper, respectively. 1000 sheets were printed, and the black solid images and black halftone images on the 1000 sheets were visually observed to determine the presence or absence of white spots, and classified as follows. A to C are within the acceptable range. A: No white spots were found. B: A very small number of white spots were observed. C: A few white spots were observed. D: White spots were observed to an unacceptable extent.

[0197] [Image unevenness] The developer was filled into the developing device of a modified image forming apparatus ApeosPort-V C7775 (FUJIFILM Business Innovation Co., Ltd.) The temperature and humidity inside the image forming apparatus were adjusted to 30° C. and 90% relative humidity, and the apparatus was left for 3 days. Immediately after leaving it for 3 days, we printed 20,000 sheets of the black image shown in Figure 3(A) (area coverage 50%, image area 100% density) on A3 plain paper. We then printed one sheet of the black image shown in Figure 3(B) (area coverage 50%, image area 100% density) on A3 plain paper. The density of the black image in FIG. 3(B) was measured at 10 points using a densitometer (product name: X-Rite938, X-Rite Corporation). The difference between the maximum and minimum image density at the 10 points was calculated and classified as follows. A to B are within the acceptable range. A: Image density difference is 0.20 or less B: Image density difference is more than 0.20 and 0.30 or less C: Image density difference is more than 0.30 and less than 0.35 D: Image density difference is more than 0.35

[0198] [Table 1]

[0199] The pigment-containing polyester resin particles, the method for producing the pigment-containing polyester resin particles, the method for producing the toner for developing electrostatic images, the toner for developing electrostatic images, the electrostatic image developer, the toner cartridge, the process cartridge, the image forming apparatus, and the image forming method according to the present disclosure include the following aspects. (((1))) A pigment-containing polyester resin particle containing a polyester resin and a pigment, the pigment is not exposed on the surface of the pigment-containing polyester resin particle and is not inscribed in the outline of the pigment-containing polyester resin particle; Pigment-containing polyester resin particles. (((2))) The pigment-containing polyester resin particles according to (((1))), having a volume average particle size of 50 nm or more and 500 nm or less. (((3))) The pigment-containing polyester resin particles according to (((1))) or (((2))), wherein the content of the pigment is 10% by mass or more and 60% by mass or less. (((4))) The pigment-containing polyester resin particles according to any one of (((1))) to (((3))), wherein the average diameter of the pigment is 10 nm or more and 400 nm or less. (((5))) The pigment-containing polyester resin particles according to any one of (((1))) to (((4))), wherein the acid value of the polyester resin is 1 mgKOH / g or more and 50 mgKOH / g or less. (((6))) A method for producing pigment-containing polyester resin particles according to any one of (((1))) to (((5))), comprising the steps of: mixing a polyester resin, a pigment, a basic compound, and a surfactant by applying heat and shear force to obtain a mixture in which the pigment is dispersed in the molten polyester resin; Adding an aqueous medium to the mixture while applying a shear force to emulsify the mixture. A method for producing pigment-containing polyester resin particles. (((7))) A method for producing pigment-containing polyester resin particles according to any one of (((1))) to (((5))), comprising the steps of: mixing a polyester resin, a pigment, and an organic solvent by applying heat and shear force to obtain a mixture in which the pigment is dispersed in the dissolved polyester resin; adding a basic compound to the mixture, and then adding an aqueous medium while applying a shear force to emulsify the mixture. A method for producing pigment-containing polyester resin particles. (((8))) forming aggregated particles by aggregating the pigment-containing polyester resin particles in a dispersion containing the pigment-containing polyester resin particles according to any one of (((1))) to (((5))); and heating the dispersion liquid containing the aggregated particles to fuse and coalesce the aggregated particles to form toner particles. A method for producing a toner for developing electrostatic images. (((9))) The toner particles include a polyester resin and a pigment, In the toner particles, the ratio of pigment particles having a maximum Feret diameter of 250 nm or more is 20% by number or less. Toner for developing electrostatic images. (((10))) An electrostatic image developer comprising the toner for developing electrostatic images according to (((9))). (((11))) (((9))) is contained in the electrostatic image developing toner, A toner cartridge that is detachably attached to an image forming apparatus. (((12))) a developing means for developing an electrostatic image formed on a surface of an image carrier into a toner image by using the electrostatic image developer according to (((10))), A process cartridge that is detachably attached to an image forming apparatus. (((13))) An image carrier; a charging means for charging the surface of the image carrier; an electrostatic image forming means for forming an electrostatic image on the charged surface of the image carrier; a developing means for containing the electrostatic image developer according to (((10))) and developing the electrostatic image formed on the surface of the image carrier into a toner image by the electrostatic image developer; a transfer means for transferring the toner image formed on the surface of the image carrier to a surface of a recording medium; a fixing means for fixing the toner image transferred onto the surface of the recording medium; An image forming apparatus comprising: (((14))) a charging step of charging the surface of the image carrier; an electrostatic image forming step of forming an electrostatic image on the charged surface of the image carrier; a developing step of developing the electrostatic image formed on the surface of the image carrier into a toner image by using the electrostatic image developer according to (((10))); a transfer step of transferring the toner image formed on the surface of the image carrier onto a surface of a recording medium; a fixing step of fixing the toner image transferred onto the surface of the recording medium; The image forming method according to claim 1,

[0200] According to (((1))), pigment-containing polyester resin particles having fewer coarse particles are provided, as compared with pigment-containing polyester resin particles in which the pigment is exposed on the surface of the pigment-containing polyester resin particle or inscribed within the contour of the pigment-containing polyester resin particle. According to (((2))), pigment-containing polyester resin particles having fewer coarse particles are provided, compared with pigment-containing polyester resin particles having a volume average particle size of less than 50 nm or more than 500 nm. According to (((3))), pigment-containing polyester resin particles having fewer coarse particles are provided, compared with pigment-containing polyester resin particles having a pigment content of less than 10% by mass or more than 60% by mass. According to (((4))), pigment-containing polyester resin particles are provided that contain fewer coarse particles, compared with pigment-containing polyester resin particles in which the average pigment diameter is less than 10 nm or more than 400 nm. According to (((5))), pigment-containing polyester resin particles having fewer coarse particles are provided, compared with pigment-containing polyester resin particles having a polyester resin acid value of less than 1 mg KOH / g or more than 50 mg KOH / g. According to (((6))), a production method for producing pigment-containing polyester resin particles containing fewer coarse particles is provided. According to (((7))), a production method for producing pigment-containing polyester resin particles containing fewer coarse particles is provided. According to ((8)), there is provided a method for producing a toner for developing electrostatic images which has excellent low-temperature fixing properties and is less susceptible to image unevenness. According to (((9))), a toner for developing electrostatic images that has excellent low-temperature fixing properties and is less likely to cause image unevenness is provided. According to (((10))), an electrostatic image developer is provided which has excellent low-temperature fixing properties and is less susceptible to image unevenness. According to (((11))), a toner cartridge is provided that contains a toner for developing electrostatic images that has excellent low-temperature fixing properties and is less likely to cause image unevenness. According to (((12))), a process cartridge is provided that contains an electrostatic image developer that has excellent low-temperature fixing properties and is less likely to cause image unevenness. According to (((13))), an image forming apparatus having excellent low-temperature fixing properties and which is less susceptible to image unevenness is provided. According to (((14))), an image forming method is provided which is excellent in low-temperature fixing property and which is less likely to cause image unevenness. [Explanation of symbols]

[0201] 1Y, 1M, 1C, 1K Photoconductor (an example of an image carrier) 2Y, 2M, 2C, 2K Charging roll (an example of a charging means) 3 Exposure device (an example of an electrostatic image forming means) 3Y, 3M, 3C, 3K laser beam 4Y, 4M, 4C, 4K developing device (an example of developing means) 5Y, 5M, 5C, 5K Primary transfer roll (an example of a primary transfer means) 6Y, 6M, 6C, 6K Photoconductor cleaning device (an example of a cleaning means) 8Y, 8M, 8C, 8K toner cartridges 10Y, 10M, 10C, 10K Image forming units 20 Intermediate transfer belt (an example of an intermediate transfer body) 22 Driving Roll 24 Support roll 26 Secondary transfer roll (an example of a secondary transfer means) 28 Fixing device (an example of a fixing means) 30 Intermediate transfer body cleaning device P Recording paper (an example of a recording medium) 107 Photoconductor (an example of an image carrier) 108 Charging roll (an example of charging means) 109 Exposure device (an example of electrostatic image forming means) 111 Developing device (an example of developing means) 112 Transfer device (an example of a transfer means) 113 Photoconductor cleaning device (an example of a cleaning means) 115 Fixing device (an example of fixing means) 116 Mounting Rail 117 Cabinet 118 Exposure Aperture 200 Process Cartridge 300 Recording paper (an example of a recording medium)

Claims

1. A pigment-containing polyester resin particle containing a polyester resin and a pigment, the pigment is not exposed on the surface of the pigment-containing polyester resin particle and is not inscribed in the outline of the pigment-containing polyester resin particle; Pigment-containing polyester resin particles.

2. 2. The pigment-containing polyester resin particles according to claim 1, having a volume average particle size of 50 nm or more and 500 nm or less.

3. The pigment-containing polyester resin particles according to claim 1 , wherein the content of the pigment is from 10% by mass to 60% by mass.

4. 2. The pigment-containing polyester resin particles according to claim 1, wherein the average diameter of the pigment is 10 nm or more and 400 nm or less.

5. 2. The pigment-containing polyester resin particles according to claim 1, wherein the acid value of the polyester resin is from 1 mgKOH / g to 50 mgKOH / g.

6. A method for producing the pigment-containing polyester resin particles according to any one of claims 1 to 5, comprising the steps of: mixing a polyester resin, a pigment, a basic compound, and a surfactant by applying heat and shear force to obtain a mixture in which the pigment is dispersed in the molten polyester resin; Adding an aqueous medium to the mixture while applying a shear force to emulsify the mixture. A method for producing pigment-containing polyester resin particles.

7. A method for producing the pigment-containing polyester resin particles according to any one of claims 1 to 5, comprising the steps of: mixing a polyester resin, a pigment, and an organic solvent by applying heat and shear force to obtain a mixture in which the pigment is dispersed in the dissolved polyester resin; adding a basic compound to the mixture, and then adding an aqueous medium while applying a shear force to emulsify the mixture. A method for producing pigment-containing polyester resin particles.

8. aggregating the pigment-containing polyester resin particles in a dispersion containing the pigment-containing polyester resin particles according to any one of claims 1 to 5 to form aggregated particles; and heating the dispersion liquid containing the aggregated particles to fuse and coalesce the aggregated particles to form toner particles. A method for producing a toner for developing electrostatic images.

9. The toner particles include a polyester resin and a pigment, In the toner particles, the ratio of pigment particles having a maximum Feret diameter of 250 nm or more is 20% by number or less. Toner for developing electrostatic images.

10. An electrostatic image developer comprising the toner for developing electrostatic images according to claim 9.

11. A toner for developing an electrostatic image according to claim 9 is contained in the toner, A toner cartridge that is detachably attached to an image forming apparatus.

12. a developing unit that contains the electrostatic image developer according to claim 10 and develops an electrostatic image formed on a surface of an image carrier into a toner image by using the electrostatic image developer, A process cartridge that is detachably attached to an image forming apparatus.

13. An image carrier; a charging means for charging the surface of the image carrier; an electrostatic image forming means for forming an electrostatic image on the charged surface of the image carrier; a developing unit that contains the electrostatic image developer according to claim 10 and develops the electrostatic image formed on the surface of the image carrier into a toner image by the electrostatic image developer; a transfer means for transferring the toner image formed on the surface of the image carrier to a surface of a recording medium; a fixing means for fixing the toner image transferred onto the surface of the recording medium; An image forming apparatus comprising:

14. a charging step of charging the surface of the image carrier; an electrostatic image forming step of forming an electrostatic image on the charged surface of the image carrier; a developing step of developing the electrostatic image formed on the surface of the image carrier into a toner image by using the electrostatic image developer according to claim 10; a transfer step of transferring the toner image formed on the surface of the image carrier onto a surface of a recording medium; a fixing step of fixing the toner image transferred onto the surface of the recording medium; The image forming method according to claim 1,

Images