Electrostatic charge image developing toner, developer, and image forming method

Abstract

An electrostatic charge image developing toner including a toner base particle and an external additive. The external additive includes at least an inorganic fine particle, the inorganic fine particle has a surface modifying agent on a surface thereof, the electrostatic charge image developing toner includes a free component, a weight-average molecular weight of the free component is 1000 or more and 20000 or less, a content of the free component is 2 mg / kg or more and 700 mg / kg or less, and the free component is a chloroform extract from a methyl ethyl ketone insoluble matter extracted from the electrostatic charge image developing toner with methanol.

Description

BACKGROUND OF THE INVENTIONTECHNICAL FIELD

[0001] The present disclosure relates to an electrostatic charge image developing toner, a developer, and an image forming method.DESCRIPTION OF RELATED ART

[0002] In recent years, in a commercial printing area, a demand for so-called high-coverage printing by a printing machine using an electrophotographic process has increased. Here, the high-coverage printing is printing with a high coverage ratio and a large amount of toner consumption. The coverage ratio is a ratio of a print range calculated from an actually used toner consumption amount when a toner consumption amount when the entire printable range in one page is printed in one color is set to 100%. Furthermore, in order to enhance productivity, speeding-up of printing is also required. In such high-coverage printing and high-speed printing, a load applied to the developer is large. That is, in recent years, printing in which a load applied to the developer is higher than ever has been increasing. In particular, in a case of using a two-component developer in which toner and carrier are mixed, a load applied to the carrier is further increased. As such, when the load applied to the carrier increases, there has been a problem that image defects tend to occur.

[0003] Conventionally, an electrostatic charge image developer that attempts to suppress a decrease in image density upon continuous output of low-area-coverage images has been disclosed (see, for example, Japanese Unexamined Patent Publication No. 2015-230376). However, it has not been possible to suppress image defects when so-called high-coverage printing is performed.

[0004] In addition, a two-component developer has been disclosed which has toner particles containing an external additive surface-modified with a silicone oil and having a high free-carbon ratio and which is intended to suppress white spots at lead portions (see, for example, Japanese Unexamined Patent Publication No. 2019-86705).SUMMARY OF THE INVENTION

[0005] If the load on the carrier is large, the core material is likely to be exposed due to abrasion of the coating resin. Then, the core material is exposed, and thus electrical resistance of the carrier decreases, with the result that developing leakage occurs in the developing nip portion. Then, image defect occurs due to the occurrence of developing leakage. In contrast, the two-component developer described in Japanese Unexamined Patent Publication No. 2019-86705 includes toner particles that are surface-modified with silicone oil and contain an external additive having a high free-carbon ratio, thereby efficiently transferring the silicone oil having insulating properties to carriers. As a result, the variation in the resistance of the carrier is suppressed, and the developing leakage is suppressed even when the developer is used for a long period of time.

[0006] On the other hand, when the free component of the silicone oil is large, the amount of the silicone oil transferred from the toner to the carrier increases. In high-coverage printing, it has been found that when the amount of the silicone oil transferred to the carrier is increased as described above, the charging performance of the carrier is deteriorated, and the density of an image varies. In high-speed, high-coverage printing, it is required to maintain stable image quality even under conditions where a load on a carrier is large and toner is frequently replaced.

[0007] The present disclosure has been made in consideration of the above-mentioned problems and situations. An object of the present disclosure is to provide an electrostatic charge image developing toner, a developer, and an image forming method capable of suppressing developing leakage and suppressing image density fluctuation.

[0008] In order to solve the above-described problems, the present disclosure has conducted intensive studies on a free component from an electrostatic charge image developing toner. As a result, the inventor of the present disclosure has found that the weight-average molecular weight and the content of a free component from the electrostatic charge image developing toner greatly affect the developing leakage and the image density fluctuation, thus arriving at the present disclosure. That is, the above problem according to the present disclosure is solved by the following means.

[0009] To achieve at least one of the abovementioned objects, according to an aspect of the present invention, electrostatic charge image developing toner reflecting one aspect of the present invention comprises: a toner base particle and an external additive, wherein the external additive includes at least an inorganic fine particle, the inorganic fine particle has a surface modifying agent on a surface thereof, the electrostatic charge image developing toner includes a free component, a weight-average molecular weight of the free component is 1000 or more and 20000 or less, a content of the free component is 2 mg / kg or more and 700 mg / kg or less, and the free component is a chloroform extract from a methyl ethyl ketone insoluble matter extracted from the electrostatic charge image developing toner with methanol.

[0010] According to the present disclosure, it is possible to provide an electrostatic charge image developing toner, a developer, and an image forming method capable of suppressing developing leakage and suppressing image density fluctuation.

[0011] The expression mechanism or action mechanism of the effect of the present disclosure is not clear, but it is presumed as follows.

[0012] The free component is a component in which the surface modifying agent of the external additive is liberated. In addition, by setting the content of the free component in a specific range, it is possible to suppress a decrease in the charging performance of the carrier due to an excessive amount of the free component. As a result, the density fluctuation of the image can be suppressed. In addition, by setting the content of the free component to be in a specific range, it is possible to suppress a change in resistance due to abrasion of the resin which coats the carrier due to the free component being too small. As a result, a decrease in the resistance of the carrier can be suppressed, and developing leakage can be suppressed. The developing leakage is caused by electric discharge generated between the photoreceptor and the carrier magnetic brush. In addition, by setting the molecular weight of the free component to be in a specific range, it is possible to suppress the charging variation without significantly reducing the chargeability of the free component. In addition, by setting the molecular weight of the free component to be in a specific range, the free component appropriately and uniformly spreads on the surface of the carrier, and it is possible to suppress a decrease in resistance of the carrier.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The advantages and features provided by one or more embodiments of the invention will become more fully understood from the detailed description given hereinbelow and the appended drawings which are given by way of illustration only, and thus are not intended as a definition of the limits of the present invention, wherein: Fig. 1 is a flowchart illustrating the image forming method of the present embodiment; and Fig. 2 is a schematic diagram schematically illustrating a cross section of the image forming apparatus used in the image forming method of the present embodiment. DETAILED DESCRIPTION

[0014] Hereinafter, one or more embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the disclosed embodiments.1. electrostatic charge image developing toner

[0015] An electrostatic charge image developing toner according to an embodiment of the present disclosure is an electrostatic charge image developing toner including toner base particles and an external additive. In the electrostatic charge image developing toner according to the present embodiment, the external additive includes at least inorganic fine particles, and the inorganic fine particles have a surface modifying agent on their surfaces. The weight-average molecular weight of the free component is 1000 or more and 20000 or less, and the content of the free component is 2 ppm or more and 700 ppm or less. The free component is a chloroform extract from the methyl ethyl ketone insoluble matter extracted with methanol from the electrostatic charge image developing toner according to the present embodiment. Hereinafter, the "electrostatic charge image developing toner of the present embodiment" may be referred to as a "toner of the present embodiment" or a "toner".

[0016] Since the electrostatic charge image developing toner of the present embodiment has the above-described configuration, when the toner is used as a developer which is a mixture with a carrier, the following effects are exhibited. That is, since the weight-average molecular weight of the free component is 1000 or more, the surface modifying agent can be maintained on the surfaces of the inorganic fine particles in the toner production process, and the free component can be transferred to the carrier. The free component is obtained by releasing the surface modifying agent attached to the surfaces of the inorganic fine particles. In addition, since the molecular weight of the free component is 20000 or less, the free component that has migrated to the surface of the carrier can suppress charging variation without significantly reducing the charging performance of the carrier. In addition, the free component appropriately and uniformly spreads on the surface of the carrier, and thus it is possible to suppress a decrease in resistance of the carrier. In order that the free component has a weight-average molecular weight of 1000 or more and 20000 or less, the viscosity of the surface modifying agent is preferably adjusted.

[0017] In addition, since the amount of the free component is 2 mg / kg or more, the free component moves to the surface of the carrier, and thus it is possible to suppress a decrease in resistance due to abrasion of the "resin which coats the carrier". In addition, since the amount of the free component is 700 mg / kg or less, the free component transferred to the surface of the carrier does not significantly deteriorate the charging performance of the carrier, and the charge variation can be suppressed. In order to adjust the content of the free component to 2 mg / kg or more and 700 mg / kg or less, the amount of the surface modifying agent and the drying conditions are preferably adjusted.<toner base particle >

[0018] In the electrostatic charge image developing toner according to the present embodiment, the toner base particle preferably contain a binder resin, a release agent, a coloring agent, and the like. Furthermore, a charge control agent may be contained. Hereinafter, the "toner base particle" may be simply referred to as "base particles". The base particles may further contain other components, if necessary.[binder resin]

[0019] A known amorphous resin can be used as the binder resin constituting the base particles contained in the electrostatic charge image developing toner according to the present embodiment. Examples of the amorphous resin include a vinyl resin, a urethane resin, a urea resin, and a polyester resin. Among these, polyester resin is preferable. By using the polyester resin, it is possible to increase the mechanical strength and the toughness of the toner, to suppress the embedding of the external additive, to increase the contact probability between the carrier and the external additive, and to make the free component of the inorganic fine particles easily migrate. On the other hand, in order to increase the mechanical strength of the toner in response to an increase in speed, it is more preferable to use a resin in combination.

[0020] The vinyl resin is not particularly limited as long as it is obtained by polymerizing vinyl compounds, and examples thereof include a (meth) acrylic acid ester resin, a styrene-(meth) acrylic acid ester resin, and an ethylenevinyl acetate resin. These may be used alone or in combination of two or more kinds thereof. Among the above-described vinyl resins, in consideration of plasticity at the time of heat fixing, a styrene-(meth) acrylic acid ester resin is preferable. Hereinafter, the styrene-(meth) acrylic acid ester resin as the amorphous resin will be described. The styrene-(meth) acrylic acid ester resin is also referred to as a "styrene-(meth) acrylic resin". The styrene-(meth) acrylic resin is formed by addition-polymerizing at least a styrene monomer and a (meth) acrylic acid ester monomer. The styrene monomer referred to herein includes, in addition to styrene represented by the structural formula of CH 2 =CH - C 6 H 5 , those having a structure having a known side chain or functional group in the styrene structure. In addition, the (meth) acrylic acid ester monomer referred to herein includes an acrylic acid ester compound or a methacrylic acid ester compound represented by CH 2 = CHCOOR (R is an alkyl group). Furthermore; the (meth) acrylic acid ester monomer includes an ester compound having a known side chain or functional group in the structure of an acrylic acid ester derivative, a methacrylic acid ester derivative or the like. Note that in the present specification, the "(meth) acrylic acid ester monomer" is a generic name for an "acrylic acid ester monomer" and a "methacrylic acid ester monomer".

[0021] An example of a styrene monomer and a (meth) acrylic acid ester monomer that can form a styrene-(meth) acrylic resin is illustrated below. Specific examples of the styrene monomer include, for example, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-tert-butylstyrene, p-n-hexylstyrene, p-n-octylstyrene, p-n-nonylstyrene, p-n-decylstyrene, p-n-dodecylstyrene and the like. These styrene monomers can be used alone or in combination of two or more kinds thereof.

[0022] Specific examples of the (meth) acrylate ester monomer include methyl acrylate, ethyl acrylate, isopropyl acrylate, butyl acrylate, t-butyl acrylate, isobutyl acrylate, N-octyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, lauryl acrylate, acrylic acid ester monomers such as phenyl acrylate; methyl methacrylate, ethyl methacrylate, butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, N-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, methacrylic acid esters such as dimethylaminoethyl methacrylate, and the like. These (meth) acrylic acid ester monomers may be used alone or in combination of two or more.

[0023] The weight-average molecular weight (Mw) of the styrene-(meth) acrylic resin is preferably 10,000 to 100,000. The method for producing the styrene-(meth) acrylic resin is not particularly limited, and examples thereof include a method in which polymerization is performed by a known polymerization method using an arbitrary polymerization initiator which is usually used for polymerization of the monomers. Examples of the polymerization initiator include peroxides, persulfides, persulfates, and azo compounds. Examples of the polymerization method include bulk polymerization, solution polymerization, emulsion polymerization, mini-emulsion, and dispersion polymerization. In addition, for the purpose of adjusting the molecular weight, a generally used chain transfer agent can be used. The chain transfer agent is not particularly limited, and examples thereof include alkyl mercaptans such as N-octyl mercaptan, and mercapto fatty acid esters.

[0024] The polyester resin constituting the binder resin is produced by a polycondensation reaction of raw materials which are a polyvalent carboxylic acid monomer (derivative) and a polyhydric alcohol monomer (derivative), in the presence of an appropriate catalyst. Examples of the polyvalent carboxylic acid monomer derivative include alkyl esters, acid anhydrides, and acid chlorides of polyvalent carboxylic acid monomers. Examples of the polyhydric alcohol monomer derivative include ester compounds of polyhydric alcohol monomers and hydroxycarboxylic acids. Examples of the polyvalent carboxylic acid monomer include for example oxalic acid, succinic acid, maleic acid, adipic acid, B-Methyladipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, fumaric acid, citraconic acid, diglycolic acid, cyclohexane-3, 5-diene-1, 2-dicarboxylic acid, malic acid, citric acid, hexahydroterephthalic acid, malonic acid, pimelic acid, tartaric acid, mucic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, P-Carboxyphenylacetic acid, p-phenylene diacetic acid, m-phenylene diglycolic acid, P-Phenylene diglycolic acid, O-Phenylene diglycolic acid, diphenylacetic acid, diphenyl-p, p'-dicarboxylic acid, naphthalene-1, 4-dicarboxylic acid, naphthalene-1, 5-dicarboxylic acid, naphthalene-2, 6-dicarboxylic acid, anthracenedicarboxylic acid, divalent carboxylic acids such as dodecenylsuccinic acid; trimellitic acid, pyromellitic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, pyrene tricarboxylic acid, and trivalent or higher-valent carboxylic acids such as pyrenetetracarboxylic acid. As the polyvalent carboxylic acid monomer, it is preferable to use an unsaturated aliphatic dicarboxylic acid such as fumaric acid, maleic acid, and mesaconic acid. Furthermore, in the present disclosure, anhydrides of dicarboxylic acids such as maleic anhydride can also be used.

[0025] Examples of the polyhydric alcohol monomer include dihydric alcohols such as ethylene glycol, propylene glycol, butanediol, diethylene glycol, hexanediol, cyclohexanediol, octanediol, decanediol, dodecanediol, an ethylene oxide adduct of bisphenol A, and a propylene oxide adduct of bisphenol A; and trihydric or higher polyols such as glycerin, pentaerythritol, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, and tetraethylolbenzoguanamine.

[0026] [release agent] As the release agent, various known waxes can be used. Examples of the wax include polyethylene wax, polyolefin wax such as polypropylene wax, branched chain hydrocarbon waxes such as microcrystalline waxes, paraffin wax, long-chain hydrocarbon-based wax such as Sasol wax, dialkyl ketone-based wax such as distearyl ketone, carnauba wax, montan wax, behenic acid behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18 octadecanediol distearate, tristearyl trimellitate, ester wax such as distearyl maleate, ethylenediamine behenylamide, amide waxes such as trimellitic acid tristearylamide, and the like. From the viewpoint of fixability, hydrocarbon-based wax is preferable.

[0027] The content of the release agent is preferably 0.1 to 30 parts by mass, and more preferably 1 to 10 parts by mass, with respect to 100 parts by mass of the binder resin. These may be used alone or in combination of two or more. Furthermore, the melting point of the release agent is preferably 50 to 95 °C from the viewpoint of the low-temperature fixability and the releasability of the toner in electrophotography.

[0028] [Charge Control Agent] As the charge control agent, various known charge control agents that can be dispersed in an aqueous medium are preferable. Specific examples thereof include nigrosine dyes, metal salts of naphthenic acid or higher fatty acid, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, salicylic acid metal salts, and salicylic acid metal complexes. The charge control agent is preferably in the form of particles.

[0029] An embodiment in which a charge control agent is not contained is also a preferable embodiment. In the case where the charge control agent is contained, the content of the charge control agent is preferably in the range of 0.1 to 10% by mass relative to the total mass of the binder resin.

[0030] Furthermore, the particle size of the charge control agent is preferably within a range of 10 to 1000 nm, more preferably within a range of 50 to 500 nm, and particularly preferably within a range of 80 to 300 nm, in terms of number-average primary particle size.[coloring agent]

[0031] The electrostatic charge image developing toner of the present embodiment may be used as a magnetic toner, but is preferably used as a non-magnetic toner from the viewpoint of exhibiting the effects of the present disclosure. The electrostatic charge image developing toner according to the present embodiment is preferably used as a color toner by incorporating a coloring agent therein.

[0032] As the coloring agent, a dye, pigment, carbon black, a magnetic material, or the like can be arbitrarily used. Among these, a dye or a pigment is preferable from the viewpoint of being able to be used as a toner.

[0033] Examples of the dye include C. I. Solvent Red 1, 49, 52, 58, 63, 111, and 122, C. I. Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, and 162, and C. I. Solvent Blue 25, 36, 60, 70, 93, and 95. They may be used alone or in combination of two or more.

[0034] Pigments include c. I. Pigment Red 5, same 48:1, same 48:3, same 53:1, same 57:1, same 81:4, same 122, same 139, same 144, same 149, same 166, same 177, same 178, same 222, c. I. Pigment Orange 31, same 43, c. I. Pigment Yellow 14, same 17, same 74, same 93, same 94, same 138, same 155, same 180, same 185, c. I. Pigment Green 7, c. I. Pigment Blue 15:3, same 15:4, same 60 and the like. They may be used alone or in combination of two or more.

[0035] Examples of the coloring agent for white include inorganic pigments and organic pigments. Inorganic pigments include, for example, titanium white, zinc white, titanium strontium white, heavy calcium carbonate, light calcium carbonate, titanium dioxide, aluminum hydroxide, satin white, talc, calcium sulfate, barium sulfate, zinc oxide, magnesium oxide, magnesium carbonate, amorphous silica, colloidal silica, white carbon, kaolin, calcined kaolin, delaminated kaolin, aluminosilicate, sericite, bentonite, smectite and the like. Examples of the organic pigment include polystyrene resin particles and urea formalin resin particles.

[0036] Examples of the carbon black include channel black, furnace black, acetylene black, thermal black, and lamp black.

[0037] Examples of the magnetic material include ferromagnetic metals such as iron, nickel, and cobalt, and further include alloys containing these metals and compounds of ferromagnetic metals such as ferrite and magnetic.

[0038] The content of the coloring agent is not particularly limited, and for example, from the viewpoint of ensuring color reproducibility of an image, the content is preferably in a range of 1 to 30% by mass, and more preferably in a range of 2 to 20% by mass with respect to the total mass of the toner base particle.

[0039] The volume mean particle diameter of the coloring agent is, for example, preferably within a range of 10 to 1000 nm, more preferably within a range of 50 to 500 nm, and still more preferably within a range of 80 to 300 nm.<external additive >

[0040] The electrostatic charge image developing toner according to the present embodiment preferably includes an external additive on the surface of the toner base particle. The external additive includes at least inorganic fine particles. The inorganic fine particles have a surface modifying agent on the surface thereof. The toner base particle may also contain, as an external additive, organic fine particles, a lubricant, and the like, in addition to the inorganic fine particles. The electrostatic charge image developing toner according to the present embodiment also includes a free component that is a chloroform extract from methyl ethyl ketone insoluble matter extracted from the electrostatic charge image developing toner with methanol.[Inorganic Fine Particles]

[0041] Examples of the inorganic fine particles include fine particles of inorganic titanate compounds such as silica fine particles; aluminum oxide fine particles; inorganic oxide fine particles such as titanium oxide fine particles; aluminum stearate fine particles; inorganic stearate compound fine particles such as zinc stearate fine particles; strontium titanate and zink titanate. The aluminum oxide fine particles are alumina fine particles. From the viewpoint of more effectively obtaining the effect of the present disclosure, the inorganic fine particle is preferably a silica fine particle. Since the silica fine particles having a high negative chargeability electrically repel PDMS having a high negative chargeability, the free component can be effectively transferred to the carrier. Furthermore, these inorganic fine particles may be subjected to gloss treatment, hydrophobic treatment, or the like with a silane coupling agent, a titanium coupling agent, a higher fatty acid, silicone oil, or the like in order to improve heat-resistant storage property, improve environmental stability, or the like.

[0042] The number-average primary particle size of the inorganic fine particles is preferably within a range of 15 to 100 nm from the viewpoint of more effectively achieving the effects of the present disclosure. The number-average primary particle size of the inorganic fine particles is more preferably in a range of 20 to 60 nm. In the case where the number-average primary particle size of the inorganic fine particles is 15 nm or more, even when the surfaces of the toner base particle have some unevenness, the inorganic fine particles are likely to come into contact with the carrier, and thus the silicone oil is likely to move to the carrier, and a sufficient function is likely to be exhibited. In addition, in a case where the number-average primary particle size of the inorganic fine particles is 100 nm or less, it becomes easier to secure the amount of the inorganic fine particles present on the surfaces of the toner base particles, thus making it easier to transfer the silicone oil to the carrier and make it easier to exhibit a sufficient function.

[0043] The number average primary particle diameter of the inorganic fine particles can be measured by the following method. An SEM photograph of the toner magnified 30, 000-fold is taken using a scanning electron microscopy (SEM) "JEM-7401F" (manufactured by JEOL Ltd), and the SEM photograph is observed to measure the particle diameter (Feret's size) of the primary particles of the silica particles. Then, the total value is divided by the number to determine the number average primary particle diameter. The particle diameter is measured by selecting an area in which the total number of particles is about 100 to 200 in the SEM image.

[0044] The amount of the inorganic fine particles to be added is preferably from 0.1 to 2 parts by mass, more preferably from 0.5 to 1.8 parts by mass, relative to 100 parts by mass of the toner. When the amount is 0.1 parts or more, a sufficient amount to be uniformly present on the toner surface is obtained. When the content is 2 parts by mass or less, the amount transferred to the carrier can be adjusted to an appropriate amount.

[0045] The amount of the free component is preferably 200 to 10000 mg / kg, more preferably 200 to 8000 mg / kg relative to the inorganic fine particles. When the amount is 200 mg / kg or more, the silicone oil moves to the surface of the carrier, and thus it is possible to suppress a decrease in resistance due to abrasion of the coating resin. When the amount is 10000 mg / kg or less, the silicone oil transferred to the surfaces of the carriers does not significantly reduce the charging ability of the carriers, and the charge variation can be suppressed.(surface modifying agent)

[0046] As the surface modifying agent, a general coupling agent, a silane compound, silicone oil, a fatty acid, a fatty acid metal salt, or the like can be used. Among these, silane compounds and silicone oils are preferable. Examples of the silane compound include chlorosilane, alkoxysilane, silazane, and a special silylating agent. Specific examples of the surface modifying agent include methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, tetramethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, diphenyldimethoxysilane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, hexamethyldisilazane, N,O-(bistrimethylsilyl) acetamide, N, N-bis (trimethylsilylurea, tert-butyldimethylchlorosilane, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-mercaptopropyltrimethoxysilane, and γ-chloropropyltrimethoxysilane.

[0047] Specific examples of the silicone oil include dimethyl silicone oil; alkyl-modified silicone oil; amino-modified silicone oil; carboxyl-modified silicone oil; epoxy-modified silicone oil; fluorine-modified silicone oil; alcohol-modified silicone oil; polyether-modified silicone oil; methylphenyl silicone oil; methyl hydrogen silicone oil; mercapto-modified silicone oil; higher fatty acid-modified silicone oil; phenol-modified silicone oil; methacrylic acid-modified silicone oil; polyether-modified silicone oil and methylstyryl-modified silicone oil. Furthermore, the silicone oil used for the surface modification may be used alone or in combination of two or more kinds thereof.

[0048] Examples of the surface modification method include a dry method, a wet method, and a mixing method. Examples of the dry method include a spray dry method in which a treatment agent or a solution containing a treatment agent is sprayed onto particles suspended in a gas phase. The wet method is a method in which particles are immersed in a solution containing a treatment agent and dried. The mixing method is a method of mixing a treatment agent and particles with a mixer.

[0049] The free component of the inorganic fine particles is preferably silicone oil from the viewpoint of insulating properties. Examples of methods for incorporating a free component of the inorganic fine particles into the toner include a method in which the free component is incorporated into the toner as a component derived from a surface modifying agent for the inorganic fine particles, a method in which the free component is additionally added to the inorganic fine particles to be incorporated into the toner, and a method in which the free component is additionally added to the toner particles to be incorporated into the toner. Of these, the method of incorporating into inorganic fine particles is preferable. In order to effectively supply the inorganic fine particles to the surface of the carrier, the surface modifying agent for the inorganic fine particles is preferably a silicone oil.[Organic Fine Particles]

[0050] As the organic fine particles, for example, spherical organic fine particles having a number-average primary particle size of about 10 to 2000 nm can be used. Specifically, organic fine particles of a homopolymer of styrene, methyl methacrylate, or the like or a copolymer thereof can be used.[Lubricant]

[0051] The lubricant is used for the purpose of further improving the cleaning performance and the transferability. As the lubricant, for example, a metal salt of a higher fatty acid is used. Specific examples of the metallic salts of higher fatty acids include, for example, salts of zinc stearate; aluminum; copper; magnesium; salts such as calcium; zinc oleate; manganese; iron; copper; salts such as magnesium; zinc palmitate; copper; magnesium; salts such as calcium; zinc linoleate; salts such as calcium; zinc ricinoleate, calcium and the like.<Free component>

[0052] The chloroform extract from the methyl ethyl ketone insoluble matter extracted with methanol from the electrostatic charge image developing toner of the present embodiment is a free component. That is, the electrostatic charge image developing toner of the present embodiment is extracted with methanol, and the solid content 1 is taken out from the obtained methanol solution. Next, a component soluble in methyl ethyl ketone is removed from the obtained solid content 1 to obtain a solid content 2. The obtained solid content 2 is extracted with chloroform, and a solid content 3 is taken out from the obtained chloroform solution. The obtained solid content 3 is a free component.

[0053] Specific methods for obtaining the free component from the electrostatic charge image developing toner of the present embodiment include, for example, the following methods. Note that the mass, volume, and the like of each substance are not limited to the following specific numerical values, and the instrument, device, conditions, and the like to be used are also not limited to the following specific instrument, device, conditions, and the like.

[0054] Toner 3 g is placed in a 50 mL screw-cap bottle, wetted with methanol 40 g, and stirred. Then, the mixture is transferred to a 60 mL disposable cup, and the tip φ36 of an ultrasound transducer is adjusted with an ultrasound homogeniser "US-1200T" (manufactured by NISSEI Corporation) so as to be immersed in the liquid to the extent of 3 cm. Thereafter, the ultrasound energy is adjusted to 100 W, and ultrasound waves are applied for 1 minute to obtain a dispersion liquid. The resulting dispersion liquid is transferred to a 15 mL tube and allowed to stand overnight, and then the supernatant is collected. The operations up to the collection of the supernatant liquid from the toner 3 g are repeatedly performed. The entire amount of the collected supernatant is concentrated to dryness. The solid obtained by concentration to dryness is refluxed with methyl ethyl ketone, and the methyl ethyl ketone-soluble matter is removed to obtain a solid content sample. Specifically, for example, after the reflux, a solid content is separated by ultra-cold centrifugation to obtain a solid content sample. The resulting solids sample is placed in a glass 50 mL centrifuge and weighed. Then, the chloroform 20 mL is placed in the centrifugation tube, and ultrasound waves are applied for 10 minutes using the ultrasound homogeniser, followed by centrifugation for 10 minutes in a 3500 rpm. The transparent supernatant obtained by centrifugation is transferred to a 100 mL eggplant-shaped flask and dried under reduced pressure. The solid matter obtained by drying under reduced pressure is subjected to the above-mentioned operation again from the above-mentioned "put into a glass 50 mL centrifugal tube and weighed" to obtain a free component. When the obtained free component is subjected to GPC measurement, the free component 2 mg is weighed, 2 mL toluene is added dropwise, and the mixture is filtered through a filter having a pore size of 0.2 µm to prepare a sample solution for GPC measurement.

[0055] The free component has a weight-average molecular weight of 1000 or more and 20000 or less. The weight-average molecular weight of the free component is preferably 1000 or more and 15000 or less, more preferably 1000 or more and 10000 or less, and particularly preferably 2000 or more and 10000 or less. In order that the free component has a weight-average molecular weight of 1000 or more and 20000 or less, the viscosity of the surface modifying agent is preferably adjusted.

[0056] The weight-average molecular weight of the free component is a weight-average molecular weight corresponding to a main peak obtained by GPC measurement using a toluene solution of the free component as a measurement sample. The GPC is gel permeation chromatography. The weight-average molecular weight corresponds to the area of the main peak. Here, the "peak" refers to an area forming a local maximum or a local minimum in the area excluding the solvent elution range in the elution curve. The "area of the peak" is the area of a "region protruding to the plus side or the minus side with respect to the base line". In the present specification, a peak having an area of 3% or more with respect to the peak area of the entire elution curve obtained by the GPC measurement is defined as a "peak". The peak obtained by the GPC measurement is a peak in an elution curve where the horizontal axis is time and the vertical axis is detection intensity. The main peak is a peak having the highest detection intensity among peaks in the elution curve. In a case where the main peak and another peak overlap each other, a perpendicular line is drawn from a point where respective curves intersect each other to the horizontal axis, the two peaks are divided into the main peak side and the other peak side by the perpendicular line, and the weight-average molecular weight on the main peak side is calculated.

[0057] When the surface modifying agent is a silicone oil, the free component is also a silicone oil. In addition, in a case where the free component is a silicone oil, a peak may be formed on the minus side in an elution curve by GPC measurement. In this case, the main peak is a "downwardly convex peak" having a minimum value and is a peak having the largest detected intensity on the negative side. The detection intensity on the minus side being the largest means that the absolute value of the detection intensity is the largest.

[0058] When the GPC measurement is performed, the free component is dissolved in toluene to prepare a toluene solution, and the toluene solution of the free component is used as a measurement sample. The sensitivity of the GPC measurement can be increased by using a solution of the free component in toluene as a sample for the GPC measurement. In particular, when the free component is silicone, the difference in refractive index between toluene and silicone is large, and highly sensitive measurement can be performed. The weight-average molecular weight can be calculated from the result of GPC measurement using a calibration curve of standard polystyrene. As a measurement apparatus, for example, HLC-8420GPC (manufactured by Tosoh Corporation) can be used. As the column, for example, Shodex K-806M (manufactured by Resonac Corporation) can be used. The conditions for GPC measurement are as follows: while the column temperature is maintained at 45°C, toluene for HPLC is allowed to flow as a carrier-solvent at a flow rate of 1. 0 mL / min. Then, 200µ L of the prepared sample liquid is injected into the GPC together with a carrier solvent, and detection is performed using a differential refractive index detector (RI detector). The calibration curves are prepared by measuring 11 standard polystyrenes (manufactured by Agilent Technologies) and N-hexylbenzene (manufactured by Tokyo Chemical Industry Co., Ltd) each having a 5.80 × 10 2< , 1.25 × 10 3< , 4.91 × 10 3< , 9.82 × 10 3< , 2.29 × 10 4< , 6.76 × 10 4< , 2.17 × 10 5< , 5.37 × 10 5< , 9.20 × 10 5< , 3.15 × 10 6< , 6.57 × 10 6< molecular weight. The GPC device, the column, and the standard polystyrene are not limited thereto as long as they have equivalent performance.

[0059] When the weight-average molecular weight of the free component is represented by Mw and the number-average molecular weight of the free component is represented by Mn, the value of Mw / Mn is preferably 1 or more and 3 or less. If the Mw / Mn value is 1 or more, components having a relatively low molecular weight are present, and thus free components uniformly wet and spread on the surface of the carrier. Further, when the value of Mw / Mn is 3 or less, the electrical properties of the free component also become uniform to some extent, so that uniform electrical properties can be maintained on the carrier surface.

[0060] The number-average molecular weight of the free component is a number-average molecular weight corresponding to a main peak obtained by GPC measurement using a measurement sample of the free component as a measurement sample. The measurement method is the same as the method for measuring the weight-average molecular weight, and the number average is calculated instead of the weight average.

[0061] The content of the free component is preferably 2 mg / kg or more and 700 mg / kg or less. The content of the free component is more preferably 2 mg / kg or more and 500 mg / kg or less. The content of the free component is the "amount of the free component extracted from the toner as described above" relative to the "amount of the entire toner" and is expressed in terms of the mass (mg) of the free component in the 1 kg of the toner. Since impurities may be mixed in the free component obtained by extraction from the toner, it is preferable to obtain the accurate mass of the free component by performing GPC measurement. The content of the free component can be obtained by GPC measurement using polydimethylsiloxane as a standard. More specifically, a polydimethylsiloxane solution having a known concentration is subjected to GPC measurement, and the concentration can be determined by an absolute calibration curve method or a standard addition method using the polydimethylsiloxane as a standard. As the polydimethylsiloxane, commercially available products (e.g., 181846-25G, manufactured by Sigma - Aldrich Co) or reagent equivalent thereto may be used. . In order to adjust the content of the free component to 2 mg / kg or more and 700 mg / kg or less, the amount of the surface modifying agent and the drying conditions are preferably adjusted.2. developer

[0062] One embodiment of the developer of the present disclosure is a mixture of the electrostatic charge image developing toner of the present embodiment described above and a carrier. The developer of the present embodiment is a mixture of the electrostatic charge image developing toner of the above-described embodiment and a carrier, and therefore can exhibit the effects of the electrostatic charge image developing toner of the present embodiment. The content of the electrostatic charge image developing toner in the developer is preferably in a range of 5 to 10 % by mass with respect to the total mass of the developer. Thus, the above-described effects of the electrostatic charge image developing toner can be effectively exhibited.<carrier>

[0063] In the developer of the present embodiment, the carrier is an aggregate of carrier particles. The carrier particles are magnetic particles capable of imparting a desired charge amount to the toner by being stirred together with the toner, and capable of conveying the charged toner to the surface of the photoreceptor. Note that after the carrier conveys the toner to the surface of the photoreceptor, the carrier returns to the inside of the developing device again, is mixed and stirred with new toner, and is repeatedly used for a certain period.

[0064] Examples of the configuration of the carrier particles include coated carrier particles in which the surface of core particles formed of a magnetic material is coated with a resin or the like, and resin-dispersed carrier particles in which a fine powder of a magnetic material is dispersed in a resin. From the viewpoint of suppressing the adhesion of the carrier particles to the photoreceptor, coated carrier particles are preferable.

[0065] The volume mean particle diameter of the carrier particles is preferably in a range of 10 to 100 µm and more preferably in a range of 20 to 80 µm. Note that the volume mean particle diameter of the carrier particles can be measured with a laser diffraction particle size distribution analyzer "HELOS" (manufactured by Sympatec GmbH) equipped with a wet disperser.[Core Material Particles]

[0066] The core particles are magnetic particles, and examples of the magnetic particles include iron powder, magnetic, various ferrite particles, and particles obtained by dispersing these particles in a resin. They may be used alone or in combination of two or more.

[0067] Of these, ferrite particles are preferable as the magnetic material particles. Since the specific gravity of the ferrite particles is smaller than that of the metal constituting the ferrite particles, the impact force of stirring in the developing device can be further reduced. Examples of the ferrite include ferrite containing a heavy metal such as copper, zinc, nickel, or manganese, and ferrite containing a light metal such as an alkali metal or an alkaline earth metal.

[0068] The core material particles preferably contain strontium (Sr). The incorporation of strontium can increase the unevenness of the surfaces of the core material particles, and even when the surfaces of the core material particles are coated with a resin or the like, the surfaces of the core material particles are easily exposed, and the resistance of the carrier is easily adjusted.[Coating Layer]

[0069] As described above, the coating layer is a layer coating the surface of the core particle. The coating material for coating the surface of the core particle is not particularly limited, but is preferably a resin. Resins suitable as the coating material used for forming the coating layer of the carriers are polyolefin resins such as polyethylene, polypropylene, chlorinated polyethylene and chlorosulfonated polyethylene; polyacrylates such as polystyrene and polymethyl methacrylate; polyvinyl and polyvinylidene resins such as polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether and polyvinyl ketone; copolymers such as vinyl chloride-vinyl acetate copolymer and styrene-acrylic acid copolymer; silicone resins comprising organosiloxane bonds or modified resins thereof; fluororesins such as polytetrachloroethylene, polyvinyl fluoride, polyvinylidene fluoride and polychlorotrifluoroethylene; polyamides; polyesters; polyurethanes; polycarbonates; amino resins such as urea-formaldehyde resins; epoxy resins; and the like. The modified resin is, for example, a modified resin of an alkyd resin, a polyester resin, an epoxy resin, a polyurethane, or the like.

[0070] Among these, particularly preferred are polyacrylate resin. In particular, since the resin formed from an alicyclic methacrylate monomer is contained, the free component transferred to the carrier tends to wet the surface due to high hydrophobicity, and thus the free component can be efficiently supplied to the carrier side. The alicyclic methacrylate monomer preferably has a cycloalkyl group having 5 to 8 carbon atoms from the viewpoint of mechanical strength, stability of charge amount, ease of polymerization, and ease of availability. Here, excellent stability of the charge amount means that an environmental difference in the charge amount is small. The alicyclic methacrylate monomer is preferably at least one selected from the group consisting of cyclopentyl (meth) acrylate; cyclohexyl (meth) acrylate; cycloheptyl (meth) acrylate and cyclooctyl (meth) acrylate. Among these, from the viewpoint of mechanical strength and environmental stability of charge amount, it is preferable to include cyclohexyl (meth) acrylate.

[0071] As the resin used for forming the coating layer of the carrier, a copolymer of an alicyclic methacrylate monomer and a chain methacrylate monomer is more preferable. In particular, methyl methacrylate is preferably used because the film strength is further increased. In addition, as a composition ratio, the alicyclic methacrylate monomer is more preferably 30 mass% or more. In a case of 30% by mass or more, an appropriate film strength is obtained, and therefore, the effect of the present disclosure is easily obtained.3 method for producing electrostatic charge image developing toner

[0072] The method for producing the electrostatic charge image developing toner of the present embodiment is not particularly limited, and examples thereof include known methods such as a kneading pulverization method, a suspension polymerization method, an emulsion aggregation method, a dissolution suspension method, a polyester elongation method, and a dispersion polymerization method. Among these, the emulsion aggregation method is preferable from the viewpoint of the uniformity of the particle size and the controllability of the shape.

[0073] The toner of the present embodiment may be specifically manufactured by a manufacturing method including the following sequence. Note that this is merely an example, and the method for manufacturing the toner according to the present embodiment is not limited to the following manufacturing method.

[0074] In the emulsion aggregation method in the manufacturing method of the toner of the present embodiment, first, a dispersion liquid of particles of a binder resin dispersed by a surfactant or a dispersion stabilizer is mixed with a dispersion liquid of particles of a coloring agent, if necessary, and aggregated until a desired toner particle diameter is obtained. In addition, shape control is performed by performing fusion between the binder resin particles. Hereinafter, the particles of the binder resin are also referred to as "binder resin particles". The particles of the coloring agent are also referred to as "coloring agent particles". Note that the binder resin particles may optionally contain a release agent, a charge control agent, and the like.

[0075] As a preferable method for producing the toner of the present embodiment, an example of a case where toner particles containing a coloring agent and having a core-shell structure are obtained using an emulsion aggregation method will be described below. This production method is a production method including the following steps (1) to (7). (1) The step of preparing a colorant particle dispersion liquid in which colorant particles are dispersed in an aqueous medium (2) a step of preparing binder resin particle dispersion liquids (dispersion liquids of binder resin particles for core particles and a shell layer) in which binder resin particles containing an internal additive (such as a release agent and a charge control agent) as necessary are dispersed in an aqueous medium; (3) Mixing the coloring agent particle dispersion and the binder resin particle dispersion for core particles to obtain a resin particle dispersion for aggregation, and aggregating and fusing the coloring agent particles and the binder resin particles for core particles in the presence of a coagulant to form aggregated particles as core particles (aggregation and fusion step) (4) Adding a binder resin particle dispersion for a shell layer containing binder resin particles for the shell layer to a dispersion containing core particles, to aggregate and fuse the binder resin particles for the shell layer on the surface of the core particles, thereby forming toner base particle having a core-shell structure (aggregation-fusion step) (5) Step of filtering out the toner base particles from the dispersion liquid of the toner base particles (toner base particle dispersion liquid) to remove the surfactant and the like (filtering out and washing steps) (6) Step of Drying Toner Base Particle (Drying Step) (7) Step of Adding External Additive to Toner Base Particle to Obtain Electrostatic Charge Image Developing Toner (External Additive Treatment Step)

[0076] The toner particles having a core-shell structure are produced by first aggregation and fusing binder resin particles for core particles and colorant particles. Next, binder resin particles for a shell layer are added to the dispersion of the core particles, and the binder resin particles for a shell layer are aggregation and fused on the surface of the core particles to form a shell layer covering the surface of the core particles. However, for example, by not adding the shell layer binder resin particle dispersion in the above step (4), toner particles formed of single-layer particles can also be produced by the same method.

[0077] In the present disclosure, the "aqueous medium" refers to a medium composed of 50 to 100% by mass of water and 0 to 50% by mass of a water-soluble organic solvent. Examples of the water solubility organic solvent include methanol, ethanol, isopropanol, butanol, acetone, methyl ethyl ketone, and tetrahydrofuran. Note that the solvent is preferably an alcohol-based organic solvent that does not dissolve the obtained resin. (1) The step of preparing a colorant particle dispersion liquid in which colorant particles are dispersed in an aqueous medium

[0078] The coloring agent particle dispersion liquid can be prepared by dispersing a coloring agent in an aqueous medium. The dispersion treatment of the coloring agent is preferably performed in an aqueous medium with the surfactant concentration equal to or higher than the critical micelle concentration (CMC) from the viewpoint of uniformly dispersing the coloring agent. Examples of a disperser used in the dispersion treatment of the coloring agent include various known dispersers.(surfactant)

[0079] Examples of the surfactant include: anionic surfactants such as alkylsulfuric acid ester salts, polyoxyethylene (n) alkyl ether sulfates, alkylbenzenesulfonates, α-olefinsulfonates, and phosphoric acid esters; amine salts such as alkylamine salts, aminoalcohol fatty acid derivatives, polyamine fatty acid derivatives, and imidazolines; quaternary ammonium salt-type cationic surfactants such as alkyltrimethylammonium salts, dialkyldimethylammonium salts, alkyldimethylbenzylammonium salts, pyridinium salts, alkylisoquinolinium salts, and benzethonium chloride; nonionic surfactants such as fatty acid amide derivatives and polyhydric alcohol derivatives; and amphoteric surfactants such as alanine, dodecyldi (aminoethyl) glycine, di(octylaminoethyl) glycine, and N-alkyl-N,N-dimethylammonium betaine. In addition, an anionic surfactant or a cationic surfactant having a fluoroalkyl group can also be used.

[0080] In this step, the dispersion diameter of the colorant particles in the prepared colorant particle dispersion liquid is preferably in a range of 10 to 300 nm in terms of volume-based median size. Note that the volume-based median diameter of the coloring agent particles contained in the coloring agent particle dispersion can be measured with an electrophoretic light scattering photometer "ELS-800" (manufactured by Otsuka Electronics Co., Ltd).

[0081] The coloring agent may be introduced into the toner base particle by dissolving or dispersing the coloring agent in a monomer solution for forming a resin in advance using a mini-emulsion method in the step of preparing binder resin particle dispersion liquids described below.

[0082] (2) a step of preparing binder resin particle dispersion liquids (dispersion liquids of binder resin particles for core particles and a shell layer) in which binder resin particles containing an internal additive (such as a release agent and a charge control agent) as necessary are dispersed in an aqueous medium; Examples of a method for dispersing the binder resin in the aqueous medium include an aqueous direct dispersion method, a dissolution-emulsification-desolvation method, and a phase inversion emulsification method. The aqueous direct dispersion method is a method in which a binder resin is dispersed in an aqueous medium to which a surfactant has been added by an ultrasonic dispersion method, a bead mill dispersion method, or the like. The dissolution-emulsification-dedissolving method is a method in which a binder resin is dissolved in a solvent, this is dispersed in an aqueous medium to form emulsified particles (oil droplets), and then the solvent is removed.

[0083] In this step, the mean particle size of the obtained binder particles is, for example, preferably within a range of 50 to 500 nm in terms of volume-based median size. Note that the volume-based median size is measured with "UPA-EX150" (manufactured by MicrotracBEL Corp).

[0084] When the binder resin is an amorphous vinyl resin, first, a liquid in which components constituting toner base particle such as a release agent and a charge control agent are optionally dissolved or dispersed in a polymerizable monomer for forming an amorphous vinyl resin is added to an aqueous medium containing a surfactant at a critical micelle concentration (CMC) or less, and mechanical energy is applied to form droplet. Next, a water solubility radical polymerization initiator is added, and a polymerization reaction is allowed to proceed in the droplet, whereby a binder resin (amorphous vinyl resin) particle dispersion can also be prepared. Note that a hydrophobic polymerization initiator may be contained in the droplet.

[0085] In this step, emulsification (formation of droplet) by applying mechanical energy is essential. Examples of a means for applying mechanical energy include a means for applying strong stirring or ultrasonic vibration energy, such as homomixer, ultrasound, and Manton-Gaulin.

[0086] In this step, the binder resin particles may include two or more layers of resin having different compositions. In this case, it is possible to use a method in which a polymerization initiator and a polymerizable monomer are added to a dispersion liquid of resin particles prepared by an emulsion polymerization treatment (first stage polymerization) according to a conventional method, and this system is further subjected to polymerization treatment (second stage polymerization, third stage polymerization).

[0087] When a surfactant is used, the same surfactant as described above can be used.(Polymerization Initiator)

[0088] The polymerization initiator is not particularly limited, and a known polymerization initiator can be used. Examples of the polymerization initiator include hydrogen peroxide, acetyl peroxide, cumyl peroxide, tert-butyl peroxide, propionyl peroxide, benzoyl peroxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, lauroyl peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, diisopropyl peroxycarbonate, tetralin hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide, pertriphenylacetic acid-tert-hydroperoxide, tert-butyl performate, tert-butyl peracetate, tert-butyl perbenzoate, tert-butyl perphenylacetate, tert-butyl permethoxyacetate, peroxides such as tert-butyl per -N-(3-toluyl) palmitate; 2,2'-azobis (2-amidinopropane) hydrochloride, 2,2'-azobis-(2-amidinopropane) nitrate, sodium 1,1'-azobis (1-methylbutyronitrile)-3-sulfonate), 4,4'-azobis-4-cyanovaleric acid, azo compounds such as poly (tetraethyleneglycol-2, 2'-azobisisobutyrate), and the like.

[0089] Of these, water solubility polymerization initiators, for example, ammonium persulfate, sodium persulfate, potassium persulfate, hydrogen peroxide, 2,2'-azobis (2-amidinopropane) hydrochloride, 2,2'-azobis-(2-amidinopropane) nitrate, 1,1'-azobis (1-methylbutyronitrile-3-sodium sulfonate) and 4,4'-azobis-4-cyanovaleric acid are preferable.

[0090] As the polymerization initiator, a redox polymerization initiator such as a combination of persulfate and metabisulfite or a combination of hydrogen peroxide and ascorbic acid may also be used.(Chain Transfer Agent)

[0091] In this step, particularly when an amorphous vinyl resin is used as the binder resin, a generally used chain transfer agent can be used for the purpose of adjusting the molecular weight of the resin. The chain transfer agent is not particularly limited, and examples thereof include alkyl mercaptan and mercapto fatty acid ester.

[0092] In the above-described step, the average particle size of the obtained binder particles is, for example, preferably within a range of 50 to 500 nm in volume-based median size. Note that the volume-based median size can be measured with "UPA-EX150" (trade name) (manufactured by MicrotracBEL Corp).(3) The step of mixing the colorant particle dispersion liquid and the binder resin particle dispersion liquid for core particles to obtain a resin particle dispersion liquid for aggregation, and aggregating and fusing the colorant particles and the binder resin particles in the presence of a coagulant to form aggregated particles as core particles (aggregation and fusion step)

[0093] This step is a step of aggregation and fusing the colorant particles and the binder resin particles contained in the dispersion liquid formed in the above step in an aqueous medium. In the step, a binder resin particle dispersion and a colorant particle dispersion are added to an aqueous medium, and these particles are aggregation and fused.

[0094] As a specific method of aggregating and fusing the coloring agent particle dispersion and the binder resin particle dispersion, for example, first, a coagulant is added to an aqueous medium to a critical aggregation concentration or more. Next, the mixture is heated to a temperature equal to or higher than the glass transition temperature of the binder resin particles and equal to or higher than the melting peak temperature of the release agent. Thus, salting-out of the coloring agent particles and the binder resin particles is allowed to proceed, and at the same time, fusion is allowed to proceed in parallel. When the particles have grown to a desired particle diameter, an aggregation terminator is added to stop the particle growth, and if necessary, heating is continued to control the particle shape.

[0095] In this method, it is preferable to heat the mixture to a temperature equal to or higher than the glass transition temperature of the binder resin as quickly as possible by minimizing the standing time after the addition of the coagulant. The reason for this is not clear, but there is a concern that the aggregation state of the particles changes depending on the standing time after salting-out, causing a problem that the particle size distribution becomes unstable or the surface properties of the fused particles change. The time required for this temperature increase is usually preferably within 30 minutes, more preferably within 10 minutes.

[0096] Furthermore, the rate of temperature increase is preferably 1°C / min or more. The upper limit of the heating rate is not particularly limited, but is preferably 15°C / min or less from the viewpoint of suppressing generation of coarse particles due to rapid progress of fusion. Further, after the temperature of the reaction system reaches a temperature equal to or higher than the glass transition temperature, it is important to maintain the temperature of the reaction system for a certain period of time to continue the fusion. As a result, the growth and fusion of the toner base particle can be effectively promoted, and the durability of the finally obtained toner can be improved.(Coagulant)

[0097] The coagulant is not particularly limited but is preferably a metal salt. Examples of the metal salt include a monovalent metal salt, a divalent metal salt, and a trivalent metal salt. Examples of the monovalent metal salt include salts of alkali metals such as sodium, potassium, and lithium. Examples of the divalent metal salt include calcium, magnesium, manganese, and copper. Examples of the trivalent metal salt include iron and aluminum. Specific examples of the metal salt include sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, and manganese sulfate. Among them, it is more preferable to use a divalent metal salt because aggregation can be promoted with a small amount and the aggregation properties can be easily controlled. They may be used alone or in combination of two or more.

[0098] When a surfactant is used, the same surfactant as described above can be used.

[0099] (4) The step of adding the dispersion liquid of binder resin particles for a shell layer containing binder resin particles for the shell layer to the dispersion liquid containing the core particles, and aggregation and fusing the particles for the shell layer on the surface of the core particles to form toner base particle having a core-shell structure (aggregation and fusing step) In the same manner as in the "step of aggregation and fusing colorant particles and binder resin particles in the presence of a coagulant to form aggregated particles as core particles (aggregation and fusion step)" of (3), the particles for a shell layer are aggregated and fused on the surface of the core particles to form toner base particle having a core-shell structure.

[0100] (5) Step of filtering out the toner base particle from the dispersion liquid of the toner base particle (toner base particle dispersion liquid) to remove the surfactant and the like (filtering out and washing step); (6) Step of drying the toner base particle (drying step), filtering out, washing step, and drying step can be performed by a known method.

[0101] (7) Step of Adding External Additive to Toner Base Particle to Obtain Electrostatic Charge Image Developing Toner (External Additive Treatment Step) The step is a step of adding and mixing an external additive to the dried toner base particle.

[0102] Examples of a method for adding the external additive include a dry method in which a powdery external additive is added to and mixed with the dried toner base particle. As a mixing apparatus, a mechanical mixing apparatus such as a Henschel mixer, a Nauta mixer, a turbula mixer, or a coffee mill can be used.

[0103] In particular, when a mixing device capable of applying shear force to particles to be processed, such as a Henschel mixer, is used and the mixing time is increased or the rotation peripheral speed of stirring blades is increased, the external additive can be firmly attached to the toner base particle.

[0104] In addition, when a plurality of types of external additives is used, the toner base particle may be mixed with all the external additives at once, or the toner base particle may be divided and mixed a plurality of times according to the external additives.4 method for producing carrier

[0105] A method for producing coated carrier particles will be described. A method for producing coated carrier particles is a method for forming a coating layer on core material particles, and examples thereof include a wet coating method and a dry coating method. In the toner of the present embodiment, a dry coating method is preferable. Hereinafter, each method will be described assuming that the coating material is a resin.(wet coating method)

[0106] Examples of the wet coating method include the following methods.(1) FLUIDIZED BED SPRAY COATING METHOD

[0107] A method in which an application liquid prepared by dissolving a coating resin in a solvent is spray-coated on the surface of a core particle using a fluidized bed, and then dried to form a coating layer.(2) Dip coating method

[0108] A method of forming a coating layer by immersing core particles in a application liquid prepared by dissolving a coating resin in a solvent to perform a coating treatment, and then drying the particles.(3) Polymerization method

[0109] A method of forming a coating layer by immersing core particles in a application liquid prepared by dissolving a monomer constituting a coating resin in a solvent to perform a coating treatment, and then performing a polymerization reaction by applying heat or the like.(dry coating method)

[0110] The dry coating method is a method in which the coating resin particles are attached to the surfaces of the core particles, and then a mechanical impact force is applied to melt or soften and fix the coating resin particles attached to the surfaces of the core particles, thereby forming a coating layer.

[0111] Specifically, the core particles, the coating resin, and, if necessary, the low-resistance fine particles are stirred at a high speed using a high-speed stirring mixer capable of applying a mechanical impact force without heating or with heating, and an impact force is repeatedly applied to the mixture. Thus, the coating resin is melted or softened and fixed to the surface of the core particles to form coating layers.

[0112] As coating conditions, in a case of heating, the temperature is preferably in a range of 80 to 130 °C, and the wind velocity causing impact force is preferably 10 m / s or more during heating and is preferably 5 m / s or less during cooling in order to suppress the aggregation of the carrier particles. In addition, the time for which the impact force is applied is preferably 20 to 60 minutes.

[0113] The resistance of the carrier can be adjusted by applying a stress to the carrier particles during or after the coating step of the resin to peel off the resin coated on the convex portions of the core material particles and moderately expose the core material particles.

[0114] In the resin coating step by the dry coating method, peeling of the resin can be caused by using a high-speed shear mixer or the like during cooling while lowering the heating temperature to 60 °C or less.

[0115] After the resin coating step, peeling of the resin can be caused by using an apparatus capable of forcible stirring, and examples thereof include a method of stirring and mixing with a turbula, a ball mill, a vibration mill, or the like.

[0116] Furthermore, heat and impact may be applied to the resin coating the core material particles to move the resin coating the convex portion of the core material particles to the concave portions of the core material particles, thereby moderately exposing the core material particles. In this case, it is preferable to take a long time to apply the impact, and specifically, it is preferable to be one and a half hours or longer.5 method for producing developer

[0117] The developer according to the present embodiment is obtained by mixing the toner according to the present embodiment and the carrier described above. The mixing apparatus used at the time of mixing is not particularly limited, and examples thereof include a Nauta mixer, a W-cone type mixer, and a V-type mixer.6 image forming method

[0118] One embodiment of the image forming method of the present disclosure is an image forming method including a developing step of performing developing with the electrostatic charge image developing toner of the present embodiment. In the image forming method of the present embodiment, developing is preferably performed using the electrostatic charge image developing toner of the present embodiment as the developer of the present embodiment. FIG. 1 is a flowchart showing the image forming method of the present embodiment. In the image forming method of the present embodiment, it is preferable to perform image formation by an electrophotographic method using the developer of the present embodiment. When the image forming method of the present embodiment is an electrophotographic method, as illustrated in FIG. 1, the image forming method preferably includes a charging step S01, an electrostatic charge image forming step S02, a developing step S03, a transfer step S04, a fixing step S05, and a cleaning step S06. The charging step S01 is a step of charging the surface of image holding members. The electrostatic charge image forming step S02 is a step of forming an electrostatic charge image on the surface of a charged image holding member. The developing step S03 is a step of developing the electrostatic charge image formed on the surface of the image holding member as a toner image. The transfer step S04 is a step of transferring a toner image formed on a surface of an image holding member onto a surface of a recording medium. The fixing step S05 is a step of fixing the toner image transferred onto the surface of the recording medium. The cleaning step S06 is a step of cleaning the surface of the image holding member.(charging step)

[0119] In this step, the electrophotographic photoreceptor is charged. The charging method is not particularly limited, and for example, a known method such as a charging roller method in which the electrophotographic photoreceptor is charged with a charging roller can be used.(electrostatic charge image forming step)

[0120] In this step, an electrostatic charge image is formed on the electrophotographic photoreceptor (electrostatic charge image carrier)

[0121] The electrophotographic photoreceptor is not particularly limited, and examples thereof include a drum-shaped photoreceptor formed of an organic photoreceptor such as polysilane or phthalopolymethine.

[0122] Formation of the electrostatic charge image is performed, for example, by uniformly charging the surface of the electrophotographic photoreceptor with a charging unit, and exposing the surface of the electrophotographic photoreceptor with an exposure means so as to form the image. The term "electrostatic charge image" refers to an image formed on the surface of the electrophotographic photoreceptor by such a charging means.

[0123] The charging means and the exposure means are not particularly limited, and known methods can be used in electrophotographic method.(developing step)

[0124] In the step, the electrostatic charge image is developed with the developer of the present embodiment to form a toner image.

[0125] A toner image is formed using the developer of the present embodiment and a DEVELOPING MEANS including a stirrer that frictionally stirs and charges the toner of the present embodiment and a rotatable magnet roller.

[0126] Specifically, in the DEVELOPING MEANS, for example, the toner of the present embodiment and the carrier are mixed and stirred, and the toner of the present embodiment is charged by friction at that time and is held on the surface of the rotating magnet roller to form a magnetic brush. Since the roller is arranged in the vicinity of the electrophotographic photoreceptor, a part of the toner of the present embodiment constituting the magnetic brush formed on the surface of the roller moves to the surface of the electrophotographic photoreceptor by an electrical attraction force. As a result, the electrostatic charge image is developed with the toner of the present embodiment to form a toner image on the surface of the electrophotographic photoreceptor.(transfer step)

[0127] In this step, the toner image is transferred onto the recording medium.

[0128] The transfer of the toner image to the recording medium is performed by charging and peeling the toner image from the recording medium.

[0129] As the transfer means, for example, a corona transfer device using corona discharge, a transfer belt, or a transfer roller can be used.

[0130] In addition, the transfer step can be performed by, for example, a mode in which an intermediate transfer member is used, a toner image is primarily transferred onto the intermediate transfer member, and then the toner image is secondarily transferred onto a recording medium, or a mode in which a toner image formed on an electrophotographic photoreceptor is directly transferred onto a recording medium.(fixing step)

[0131] The toner image transferred to the recording medium is an unfixed image. In the step, the recording medium on which the toner has been transferred and the unfixed image has been formed is passed between the heated fixing belt or fixing roller and the pressure member, so that the unfixed image is fixed onto the recording medium.

[0132] As a method of the fixing step, for example, a belt fixing method or a roller fixing method including a fixing belt or a fixing roller as a fixing rotating body and a pressure roller as a pressure member provided in a state of being pressed against the fixing belt or the fixing roller so as to form a fixing nip part may be mentioned.(cleaning step)

[0133] In this step, the developer that has not been used for image formation or that has not been transferred and remains on the developer carrier such as the photoreceptor or the intermediate transfer member is removed from the developer carrier.

[0134] The cleaning method is not particularly limited, and examples thereof include a method using a blade whose tip is provided in contact with the target to be cleaned such as the photoreceptor and which rubs the surface of the photoreceptor.(recording medium)

[0135] The recording medium is not particularly limited. Examples of the recording medium include paper such as plain paper ranging from thin paper to thick paper, wood-free paper, coated printing sheet such as art paper or coated sheet, commercially available Japanese paper or postcard sheet; resin films such as a polypropylene (PP) film, a polyethylene terephthalate (PET) film and a triacetyl cellulose (TAC) film; and a fabric. The color of the recording medium is not particularly limited, and recording media of various colors can be used.7 image forming apparatus

[0136] An image forming apparatus used for the image forming method of the present embodiment will be described. When the image forming method is an electrophotographic method, for example, an image forming apparatus 100 as illustrated in Fig. 2 can be used as the image forming apparatus. Fig. 2 is a schematic diagram schematically illustrating a cross section of the image forming apparatus used in the image forming method of the present embodiment. The image forming apparatus 100 is called a tandem-type color image forming apparatus. The image forming apparatus 100 includes four image forming sections (image forming units) 10Y, 10M, 10C, and 10Bk arranged in tandem in a vertical direction, an intermediate transfer unit 7, a sheet feed means 21, and a fixing means 24. At an upper part of a main body A of the image forming apparatus 100, a document image scanning device SC is arranged.

[0137] The intermediate transfer unit 7 includes an endless belt-shaped intermediate transfer body 70 which is rotatable by being wound around rollers 71, 72, 73, and 74, primary transfer rollers 5Y, 5M, 5C, and 5Bk, and CLEANING MEANS 6b.

[0138] Four image forming units 10Y, 10M, 10C, and 10Bk have drum-shaped photoreceptors 1Y, 1M, 1C, and 1Bk at their centers, respectively, and also have charging means 2Y, 2M,2C, and 2Bk, exposure means 3Y 3M 3C 3Bk, rotating developing means 4Y 4M 4C 4Bk, and cleaning means 6Y 6M 6C 6Bk for cleaning the photoreceptors 1Y 1M 1C 1Bk.

[0139] The image forming unit 10Y, 10M, 10C, and 10Bk form toner images in yellow, magenta, cyan, and black, respectively. The charging step, the exposure step, and the developing step in the image forming method according to the present embodiment are steps of forming a toner image on the photoreceptor. In the image forming apparatus 100, the following process is performed in the image forming units 10Y, 10M, 10C, and 10Bk using the photoreceptors 1Y, 1M, 1C, and 1Bk and the toner of the present embodiment. The toner of the present embodiment is preferably mixed with a carrier and used as the developer of the present embodiment.

[0140] The image forming units 10Y, 10M, 10C, and 10Bk have the same configuration except that the colors of the toner images formed on the photoreceptors 1Y, 1M, 1C, and 1Bk are different from each other, and thus the image forming unit 10Y will be described in detail as an example.

[0141] The image forming unit 10Y includes a charging means 2Y, an exposure means 3Y, a developing means 4Y, and a cleaning means 6Y, which are disposed around a photoreceptor 1Y that is an image forming body. The image forming unit 10Y forms a yellow (Y) toner image on the photoreceptor 1Y. Furthermore, in the image forming apparatus 100, at least the photoreceptor 1Y, the charging means 2Y, the DEVELOPING MEANS 4Y, and the CLEANING MEANS 6Y of the image forming unit 10Y are provided so as to be integrated.

[0142] The charging means 2Y is a unit that applies a uniform potential to the photoreceptor 1Y. In the image forming apparatus 100, examples of the charging means include a contact or non-contact roller charging method. Among these, a contact roller charging method is preferable from the viewpoint that the effect of the toner of the present embodiment becomes more effective.

[0143] The exposure means 3Y is a means that performs exposure based on an image signal (yellow), on the photoreceptor 1Y to which a uniform potential has been applied by the charging means 2Y, so as to form an electrostatic charge image corresponding to a yellow image. Examples of the exposure means 3Y include one composed of LEDs and image forming elements in which light emitting elements are arranged in an array in the axis direction of the photoreceptor 1Y, and one using a laser optical system.

[0144] The DEVELOPING MEANS 4Y is composed of, for example, a developing sleeve which incorporates a magnet and rotates while holding a two-component developer, and a voltage applying device which applies a direct current or an alternating current bias voltage between the photoreceptor 1Y and the developing sleeve.

[0145] The CLEANING MEANS 6Y is composed of a cleaning blade and a brush roller provided on the upstream side from the cleaning blade. The cleaning blade is provided such that its tip comes in contact with the surface of the photoreceptor 1Y. The brush roller is in contact with the surface of the photoreceptor 1Y. The cleaning blade has the function of scraping the surface of the photoreceptor 1Y as well as the function of removing the residual toner attached on the photoreceptor 1Y.

[0146] The brush roller has functions of removing the residual toner attached on the photoreceptor 1Y, collecting the residual toner removed by the cleaning blade, and scraping the surface of the photoreceptor 1Y. That is, the brush roller comes into contact with the surface of the photoreceptor 1Y. At the contact portion, the cleaning blade rotates in the same direction as the photoreceptor 1Y, removes residual toner and paper dust on the photoreceptor 1Y, and conveys and collects the residual toner removed by the cleaning blade.

[0147] In the image forming method using the image forming apparatus 100, an intermediate transfer is used in the transfer step. Specifically, a toner image formed on a photoreceptor is primarily transferred onto an intermediate transfer member, and then the toner image is secondarily transferred onto a recording medium.

[0148] The toner images in the respective colors formed by the image forming units 10Y, 10M, 10C, and 10Bk are sequentially transferred, by primary transfer rollers 5Y, 5M, 5C, and 5Bk serving as primary transfer means, onto a rotating endless belt-shaped intermediate transfer unit 70 of an intermediate transfer unit 7. Then, a superimposed color image is formed. The endless belt-shaped intermediate transfer member 70 is a semiconductive endless belt-shaped second image holding member wound around and rotatably supported by a plurality of rollers 71, 72, 73, and 74.

[0149] The color image synthesized on the endless belt-shaped intermediate transfer member 70 is then transferred to a recording medium P. The recording medium P is an image support that carries a fixing last image. Examples of the recording medium P include plain paper and a transparent sheet. Specifically, the recording medium P accommodated in the sheet feed cassette 20 is sheet fed by the sheet feed means 21. Next, the recording medium P is conveyed to a secondary transfer roller 5b as a secondary transfer means via a plurality of intermediate rollers 22A, 22B, 22C, and 22D, and registration roller 23. Then, the color images are collectively transferred (secondarily transferred) from the endless belt-shaped intermediate transferer 70 onto the recording medium P by the secondary transfer roller 5b. The recording medium P onto which the image has been transferred is subjected to fixing processing by the fixing means 24, pinched between the sheet ejection roller 25, and placed on a sheet ejection tray 26 outside the apparatus.

[0150] The fixing means 24 is, for example, of a heat roller fixing type which is composed of a heating roller internally provided with a heating source and a pressure roller provided in a state of being pressed against the heating roller so as to form a fixing nip part.

[0151] On the other hand, after the color image is transferred onto the recording medium P by the secondary transfer roller 5b as the secondary transfer means, the endless belt-shaped intermediate transfer member 70 from which the recording medium P is separated by curvature is subjected to removal of residual toner by the CLEANING MEANS 6b.

[0152] During the image formation processing, the primary transfer roller 5Bk is constantly in contact with the photoreceptor 1Bk. The other primary transfer rollers 5Y, 5M, and 5C contact the corresponding photoreceptors 1Y, 1M, and 1C, respectively, only when a color image is formed. The secondary transfer roller 5b comes into contact with the endless belt-shaped intermediate transfer member 70 only when the recording medium P passes therethrough and the secondary transfer is performed.

[0153] Furthermore, in the image forming apparatus 100, the image forming sections 10Y, 10M, 10C, and 10Bk and the housing 8 including the intermediate transfer unit 7 can be pulled out from the apparatus body A via the support rails 82 L and 82R.

[0154] An image forming apparatus 100 illustrated in Fig. 2 is an image forming apparatus in a color laser printer. Other examples of the image forming apparatus used in the image forming method of the present embodiment include a monochrome laser printer and a copier. In addition, as the exposure light source, a light source other than a laser, for example, an LED light source may be used.

[0155] [Example] Hereinafter, the present disclosure will be specifically described with reference to examples, but the present disclosure is not limited thereto. In the following Examples, operations are performed at room temperature (25°C) unless otherwise specified, and % by mass means mass%.<Electrostatic Charge Image Developing Toner >[Production of Inorganic Fine Particles] (Preparation of Silica Particle 1)

[0156] Silica particles 1 were prepared as inorganic fine particles to be used as an external additive. A hexane solvent was prepared by diluting 10 parts by mass of silicone oil having a kinetic viscosity of 100 mm 2< / s at 25 °C with 50 parts by mass of hexane. The silicone oil is a surface modifying agent. As the silicone oil, "KF96 100cs (trade name)" manufactured by Shin - Etsu Chemical Co., Ltd. was used. Sixty (60) parts by mass of the hexane solution was sprayed onto 100 parts by mass of the silica particles while the silica particles were stirred under a nitrogen atmosphere. Silica particles prepared by a gas phase method and having a number average primary particle diameter of 40 nm were used as the silica particles. The resultant reaction mixture was stirred at 250°C for 60 minutes under a nitrogen airflow, dried, and cooled, and silica particles were collected. In the column of surface modification 1 in Table 1, the blending amount (parts by mass) of the surface modifying agent is the blending amount (parts by mass) relative to 100 parts by mass of the silica particles.

[0157] The collected silica particles were put into hexane, subjected to a dispersion treatment for 10 minutes using an ultrasound disperser, and then centrifuged, and the precipitate was collected and dried under reduced pressure. A hexane solvent was prepared by diluting 0.5 parts by mass of a silicone oil having a kinetic viscosity of 10 mm 2< / s at 25 °C with 25 parts by mass of hexane. As the silicone oil, "KF96 10cs (trade name)" manufactured by Shin - Etsu Chemical Co., Ltd. was used. To 50 parts by mass of the solid content dried under reduced pressure, 25.5 parts by mass of the hexane solution was sprayed while stirring the solid content under a nitrogen atmosphere. The reaction mixture was stirred at 300°C for 60 minutes under a nitrogen airflow, dried, and cooled, and silica particle 1 was collected. In the column of surface modification 2 in Table 1, the blending amount (parts by mass) of the surface modifying agent is a blending amount (parts by mass) with respect to 50 parts by mass of the silica particles. The particle diameter of the silica particles 1 can be varied by the reaction conditions in the gas-phase process, for example the flame temperature, the hydrogen or oxygen content, the residence time in the flame or the length of the aggregation zone.(Preparation of Silica Particles 2 to 7, 11 to 17, and 23 to 29)

[0158] Silica particles 2 to 7, 11 to 17, and 23 to 29 were produced as the inorganic fine particles. Silica particles 2 to 7, 11 to 17, and 23 to 29 were produced in the same manner as the silica particle 1 except that the conditions of the surface modification were changed as illustrated in Table 1. In Tables 1 and 2, "Silica 1 to Silica 29" means "Silica particle 1 to silica particle 29".(Production of Silica Particle 8)

[0159] Silica particles 8 were prepared as inorganic fine particles. A hexane solvent was prepared by diluting 10 parts by mass of silicone oil having a kinetic viscosity of 100 mm 2< / s at 25 °C with 50 parts by mass of hexane. The silicone oil is a surface modifying agent. As the silicone oil, "KF96 100cs (trade name)" manufactured by Shin - Etsu Chemical Co., Ltd. was used. Sixty (60) parts by mass of the hexane solution was sprayed onto 100 parts by mass of the silica particles while the silica particles were stirred under a nitrogen atmosphere. Silica particles prepared by a gas phase method and having a number average primary particle diameter of 40 nm were used as the silica particles. The resultant reaction mixture was stirred at 250°C for 60 minutes under a nitrogen airflow, dried, and cooled, and silica particles were collected.

[0160] A hexane solvent was prepared by diluting 0.5 parts by mass of silicone oil having a kinetic viscosity of 200 mm 2< / s at 25 °C with 25 parts by mass of hexane. As the silicone oil, "KF96 200cs (trade name)" manufactured by Shin - Etsu Chemical Co., Ltd. was used. While the silica particles were stirred under a nitrogen atmosphere, 25.5 parts by mass of the hexane solution was sprayed onto 50 parts by mass of the collected silica particles. The reaction mixture was stirred at 250°C for 60 minutes under a nitrogen airflow, dried, and cooled, and silica particles 8 were collected.Preparation of Silica Particles 9 and 10)

[0161] Silica particles 9 and 10 were produced as inorganic fine particles. Silica particles 9and10 were produced in the same manner as the silica particle 8 except that the conditions for the surface modification were changed as illustrated in Table 1.(Production of Silica Particles 18 to 22)

[0162] Silica particles 18 to 22 were prepared as inorganic fine particles. Silica particles 18 to 22 were prepared in the same manner as the silica particle 1 except that the particle diameter of the silica particle was changed as illustrated in Table 2. The particle diameter of the silica particles was adjusted by changing the reaction conditions when the silica particles were prepared by a gas phase method. The reaction conditions varied were the flame temperature, the content of hydrogen or oxygen, the residence time in the flame or the length of the aggregation zone.[Table 1]

[0163] TABLE 1 EXTERNAL ADDITIVE SURFACE MODIFICATION 1 SURFACE MODIFICATION 2 INORGANIC FINE PARTICLE SURFACE MODIFYING AGENT BLENDING AMOUNT (PARTS BY MASS) SURFACE MODIFYING AGENT BLENDING AMOUNT (PARTS BY MASS) SILICA 1 KF-96-100cs 10 KF-96-10cs 0.5 SILICA 2 KF-96-100cs 10 KF-96-50cs 0.5 SILICA 3 KF-96-100cs 10 KF-96-50cs 0.2 KF-96-100cs 0.3 SILICA 4 KF-96-100cs 10 KF-96-100cs 0.5 SILICA 5 KF-96-100cs 10 KF-96-200cs 0.5 SILICA 6 KF-96-100cs 10 KF-96-300cs 0.5 SILICA 7 KF-96-100cs 10 KF-96-350cs 0.5 SILICA 8 KF-96-100cs 10 KF-96-200cs 0.5 SILICA 9 KF-96-100cs 10 KF-96-100cs 0.5 SILICA 10 KF-96-100cs 10 KF-96-10cs 2 SILICA 11 KF-96-50cs 10 KF-96-10cs 0.5 SILICA 12 KF-96-100cs 10 KF-96-50cs 0.1 SILICA 13 KF-96-100cs 10 KF-96-50cs 0.2 SILICA 14 KF-96-100cs 10 KF-96-50cs 1 SILICA 15 KF-96-100cs 10 KF-96-50cs 1.2 SILICA 16 KF-96-100cs 10 KF-96-50cs 1.3 SILICA 17 KF-96-100cs 10 KF-96-50cs 3 SILICA 18 KF-96-100cs 10 KF-96-50cs 0.5 SILICA 19 KF-96-100cs 10 KF-96-50cs 0.5 SILICA 20 KF-96-100cs 10 KF-96-50cs 0.5 SILICA 21 KF-96-100cs 10 KF-96-50cs 0.5 SILICA 22 KF-96-100cs 10 KF-96-50cs 0.5 SILICA 23 KF99 10 KF-96-20cs 0.5 SILICA 24 X-21-5841 10 KF-96-100cs 0.5 SILICA 25 XBE-3083 10 KF-96-100cs 0.5 SILICA 26 KF-96-100cs 10 KF-96-500cs 2 SILICA 27 KF-96-100cs 10 KF-96-10cs 0.5 SILICA 28 KF-96-100cs 10 KF-96-50cs 0.05 SILICA 29 KF-96-100cs 10 KF-96-50cs 5

[0164] In Table 1, "KF99" represents methylhydrogenpolysiloxane. "X-21-5841" represents silanol-terminated silicone oil, and is dimethylpolysiloxane of which both terminals are silanol-modified. "XBE-3083" refers to octyltriethoxysilane. "KF-96-10cs" indicates polydimethylsiloxane (PDMS), and the kinetic viscosity at 25°C is 10 mm 2< / s. Similarly, "KF-96-50cs", "KF-96-100cs", "KF-96-200cs", "KF-96-300cs", "KF-96-350cs", and "KF-96-500cs" also indicate polydimethylsiloxane (PDMS), and a numerical value immediately preceding "cs" of each of them indicates a kinetic viscosity (mm 2 / < / s) at 25 °C.[Table 2]

[0165] TABLE IIEXTERNAL ADDITIVE SURFACE MODIFICATION TONER CARRIER FREE COMPONENT INORGANIC FINE PARTICLE *1 SURFACE MODIFYING AGENT *2 TYPE *3 TYPE Mw Mn Mw / Mn *4 EXAMPLE 1 SILICA 1 40 PDMS 6200 TO NER BASE PARTICLE 1 1.1 CARRIER 1 2000 1200 1.7 52 EXAMPLE 2 SILICA 2 40 PDMS 5800 TO NER BASE PARTICLE 1 1.1 CARRIER 1 7500 6300 1 130 EXAMPLE 3 SILICA 3 40 PDMS 8000 TO NER BASE PARTICLE 1 1.1 CARRIER 1 10000 8800 1.1 240 EXAMPLE 4 SILICA 4 40 PDMS 8500 TO NER BASE PARTICLE 1 1.1 CARRIER 1 10800 8800 1.2 300 EXAMPLE 5 SILICA 5 40 PDMS 4900 TO NER BASE PARTICLE 1 1.1 CARRIER 1 15000 9100 1.6 230 EXAMPLE 6 SILICA 6 40 PDMS 4990 TO TONER BASE PARTICLE 1 1.1 CARRIER 1 18800 15000 1.3 280 EXAMPLE 7 SILICA 7 40 PDMS 6300 TO NER BASE PARTICLE 1 1.1 CARRIER 1 20000 14000 380 EXAMPLE 8 SILICA 8 40 PDMS 8000 TO NER BASE PARTICLE 1 1.1 CARRIER 1 16000 5400 3.0 400 EXAMPLE 9 SILICA 9 40 PDMS 4000 TO NER BASE PARTICLE 1 1.1 CARRIER 1 9800 4000 2. 11 EXAMPLE 10 SILICA 10 40 PDMS 6800 TO NER BASE PARTICLE 1 1.1 CARRIER 1 5000 2700 1. 402 EXAMPLE 11 SILICA 11 40 PDMS 5000 TO NER BASE PARTICLE 1 1.1 CARRIER 1 1000 800 1.3 15 EXAMPLE 12 SILICA 12 40 PDMS 200 TO NER BASE PARTICLE 1 1.1 CARRIER 1 7500 6300 1 2 EXAMPLE 13 SILICA 13 40 PDMS 300 TO NER BASE PARTICLE 1 1.1 CARRIER 1 7500 6300 1.2 1 EXAMPLE 14 SILICA 14 40 PDMS 8000 TO NER BASE PARTICLE 1 1.1 CARRIER 1 7500 6300 1.2 200 EXAMPLE 15 SILICA 15 40 PDMS 10000 TO NER BASE PARTICLE 1 1.1 CARRIER 1 7500 6300 1.2 222 EXAMPLE 16 SILICA 16 40 PDMS 11000 TO NER BASE PARTICLE 1 1.1 CARRIER 1 7500 6300 1.2 250 EXAMPLE 17 SILICA 17 40 PDMS 30000 TO TONER BASE PARTICLE 1 1.1 CARRIER 1 7500 6300 1.2 680 EXAMPLE 18 SILICA 18 10 PDMS 8200 TO TONER BASE PARTICLE 1 0.4 CARRIER 1 7500 6300 1.2 104 EXAMPLE 19 SILICA 19 20 PDMS 6300 TO NER BASE PARTICLE 1 0.9 CARRIER 1 7500 6300 1.2 98 EXAMPLE 20 SILICA 20 60 PDMS 5900 TO NER BASE PARTICLE 1 0.9 CARRIER 1 7500 6300 1.2 111 EXAMPLE 21 SILICA 21 80 PDMS 4800 TO NER BASE PARTICLE 1 2 CARRIER 1 7500 6300 1.2 202 EXAMPLE 22 SILICA 22 110 PDMS 3000 TO NER BASE PARTICLE 1 3 CARRIER 1 7500 6300 1.2 183 EXAMPLE 23 SILICA 2 40 PDMS 5800 TO NER BASE PARTICLE 2 1.1 CARRIER 1 7500 6300 1.2 130 EXAMPLE 24 SILICA 2 40 PDMS 5800 TO NER BASE PARTICLE 1 1.1 CARRIER 2 7500 6300 1.2 130 EXAMPLE 25 TITANIA 20 PDMS 4500 TO NER BASE PARTICLE 1 1.8 CARRIER 1 7500 6300 1.2 144 EXAMPLE 26 SILICA 23 40 MHSO 5000 TO NER BASE PARTICLE 1 1.1 CARRIER 1 3200 2000 1.6 99 EXAMPLE 27 SILICA 24 40 SNSO 1000 TO NER BASE PARTICLE 1 1.1 CARRIER 1 8200 6200 1. 25 EXAMPLE 28 SILICA 25 40 OTES 200 TO NER BASE PARTICLE 1 1.1 CARRIER 1 7800 6500 1.2 5 EXAMPLE 29 SILICA 2 40 PDMS 5800 TO NER BASE PARTICLE 1 0.1 CARRIER 1 7500 6300 1.2 15 EXAMPLE 30 SILICA 2 40 PDMS 5800 TO NER BASE PARTICLE 1 0.5 CARRIER 1 7500 6300 1.2 7 22 EXAMPLE 31 SILICA 2 40 PDMS 5800 TO NER BASE PARTICLE 1 1.8 CARRIER 1 7500 6300 1.2 EXAMPLE 32 SILICA 2 40 PDMS 5800 TO NER BASE PARTICLE 1 2.2 CARRIER 1 7500 6300 1.2 300 COMPARATIVE EXAMPLE 1 SILICA 26 40 PDMS 2000 TO NER BASE PARTICLE 1 1.1 CARRIER 1 22000 10000 2.2 130 COMPARATIVE EXAMPLE 2 SILICA 27 40 PDMS 4500 TO NER BASE PARTICLE 1 1.1 CARRIER 1 900 700 1.3 COMPARATIVE EXAMPLE 3 SILICA 28 40 PDMS 100 TO NER BASE PARTICLE 1 1.1 CARRIER 1 7500 6300 1.2 1 COMPARATIVE EXAMPLE 4 SILICA 29 40 PDMS 33000 TO NER BASE PARTICLE 1 1.1 CARRIER 1 7500 6300 1.2 750 *1: PARTICLE DIAMETER *2: FREE COMPONENT CONTENT IN THE SILICA (mg / kg) *3: INORGANIC FINE PARTICLE CONTENT (PARTS BY MASS) *4: CONTENT IN TONER (mg / kg)

[0166] In Table II, "PDMS" refers to polydimethylsiloxane. "MHSO" indicates methylhydrogenpolysiloxane. "SNSO" indicates a silanol-terminated silicone oil and is "X-21-5841" described in Table I. "OTES" is "XBE-3083" as described in Table I, indicating octyltriethoxysilane. The inorganic fine particle content (parts by mass) in the column of toner means the content (parts by mass) of inorganic fine particles relative to 100 parts by mass of toner. In the column of "Content of free components in silica" in Table II, the content of free components in titania is described for example 25.(Production of Titania Particle 1)

[0167] Titania particle 1 was prepared as an inorganic fine particle. Titania particles 1 are prepared in the same manner as the silica particles 2, except that the titania particles are used instead of the silica particles. Titania particles prepared by a gas phase method and having a number average primary particle diameter of 20 nm were used as the titania particles.[Preparation of Toner Base Particle][Preparation of Styrene - Acrylic Resin Particle Dispersion](first stage polymerization)

[0168] A reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introduction device was charged with an aqueous surfactant solution prepared by dissolving 4 parts by mass of an anionic surfactant in 3040 parts by mass of ion-exchanged water. As the anionic surfactant, sodium dodecyl sulfate was used. Furthermore, a polymerization initiator solution in which 10 parts by mass of potassium persulfate (KPS) was dissolved in 400 parts by mass of ion-exchanged water was added, and the liquid temperature was raised to 75°C.

[0169] Next, a polymerizable monomer solution containing 532 parts by mass of styrene, 200 parts by mass of N-butylacrylic acid, 68 parts by mass of methacrylic acid, and 16.4 parts by mass of N-octylmercaptan was added dropwise thereto over 1 hour. After the dropwise addition, the mixture was heated and stirred at 75°C for 2 hours to perform polymerization (first stage polymerization), thereby preparing a dispersion liquid of styrene-acrylic resin particles. The styrene-acrylic resin particles may be referred to as "StAc resin particles" or "StAc".

[0170] The weight-average molecular weight (Mw) of the StAc resin particles in the dispersion of the StAc resin particles was 16500. The weight-average molecular weight (Mw) is determined by gel permeation chromatography (GPC: Gel Permeation Chromatography The weight average molecular weight was determined from the molecular weight distribution. Specifically, the measurement sample was added to tetrahydrofuran (THF) so as to have a concentration of 1 mg / mL, and dispersed for 5 minutes at room temperature using an ultrasonic disperser to obtain a THF solvent of the measurement sample. Thereafter, the THF solution was treated with a filter having a pore size of 0.2 µm to prepare a sample solution. For the GPC measurement, a GPC device HLC-8120GPC (manufactured by Tosoh Corporation) was used. As columns, three columns of "TSKguardcolumn + TSKgelSuperHZ -m" (manufactured by Tosoh Corporation) were used. In the measurement, tetrahydrofuran as carrier solvent was allowed to flow at a flow rate of 0. 2 mL / min while the column temperature was maintained at 40°C. Together with the carrier solvent, 10µ L of the prepared sample solution was injected into the GPC device, the sample was detected using a refractive index detector (RI detector), and the molecular weight distribution of the sample was calculated using the calibration curve. As the calibration curve, a calibration curve measured using monodisperse polystyrene standard particles was used. The calibration curve was prepared by measiring 10 polystyrene standard particles (manufactured by Pressure Chemical Co., Ltd) satisfying the molecular weight of 6×10 2< , 2.1×10 3< , 4×10 3< , 1.75×10 4< , 5.1×10 4< , 1.1×10 5< , 3.9×10 5< , 8.6×10 5< , 2×10 6< , and 4.48×10 6< .(second stage polymerization)

[0171] A flask equipped with a stirrer was charged with a polymerizable monomer solution containing 101.1 parts by mass of styrene, 62.2 parts by mass of N-butylacrylic acid, 12.3 parts by mass of methacrylic acid, and 1.75 parts by mass of N-octylmercaptan. Furthermore, 93.8 parts by mass of paraffin wax HNP-57 (manufactured by Nippon Wax Industries Co., Ltd) as a release agent was added, and the internal temperature was raised to 90°C to dissolve it, thereby preparing a monomer solution.

[0172] Another container was charged with an aqueous surfactant solution prepared by dissolving 3 parts by mass of the surfactant used in the first stage polymerization in 1560 parts by mass of ion-exchanged water. The aqueous surfactant solution was heated to 98°C. To this aqueous surfactant solution, 32.8 parts by mass (in terms of solid content) of the dispersion liquid of styrene-acrylic resin particles obtained by the first stage polymerization was added, and furthermore, the monomer solution containing paraffin wax was added. Using a mechanical disperser CLEARMIX (manufactured by M Technique Co., Ltd) having a circulation path, the mixture was mixed and dispersed over 8 hours. Thus, a dispersion liquid of emulsified particles (oil droplets) having a particle size of 340 nm was prepared.

[0173] To this dispersion liquid, a polymerization initiator solution prepared by dissolving 6 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water was added. The system was heated and stirred at 98°C for 12 hours to perform polymerization (second stage polymerization), thereby preparing a dispersion liquid of styrene-acrylic resin particles. The styrene-acrylic resin particles in the dispersion liquid had a weight-average molecular weight (Mw) of 23000.(third stage polymerization)

[0174] To the dispersion liquid of styrene-acrylic resin particles obtained in the second stage polymerization, a polymerization initiator solution prepared by dissolving 5.45 parts by mass of potassium persulfate in 220 parts by mass of ion-exchanged water was added. To this dispersion liquid, a polymerizable monomer solution containing 293.8 parts by mass of styrene, 154.1 parts by mass of N-butylacrylic acid, and 7.08 parts by mass of N-octylmercaptan was added dropwise over 1 hour under a temperature condition of 80°C. After the completion of the dropwise addition, the mixture was heated and stirred for 2 hours to perform polymerization (third stage polymerization). After the polymerization, the mixture was cooled to 28°C to obtain a dispersion liquid of target styrene-acrylic resin particles. The styrene-acrylic resin particles in the dispersion liquid had a weight-average molecular weight (Mw) of 26800.[Preparation of Amorphous Polyester Particle Dispersion]

[0175] A polyvalent carboxylic acid monomer and a polyhydric alcohol monomer were charged into a reaction vessel equipped with a stirrer, a nitrogen inlet tube, a temperature sensor, and a rectifying column. As polyvalent carboxylic acid monomers, 139.5 parts by mass of terephthalic acid and 15.5 parts by mass of isophthalic acid were charged. As the polyhydric alcohol monomers, 290.4 parts by mass of 2,2-bis (4-hydroxyphenyl) propanepropyleneoxide 2 mol adduct (molecular weight = 460) and 60.2 parts by mass of 2,2-bis (4-hydroxyphenyl) propaneethyleneoxide 2 mol adduct (molecular weight = 404) were charged.

[0176] The temperature of the reaction system charged in the reaction vessel was raised to 190°C over 1 hour, and after confirming that the inside of the reaction system was uniformly stirred, 3.21 parts by mass of tin octylate as a catalyst was charged. While the produced water was distilled off, the temperature of the reaction system was raised from the same temperature to 240°C over 6 hours, and a dehydration condensation reaction was continued for 6 hours in a state of being maintained at 240°C, to obtain an amorphous polyester resin. The obtained amorphous polyester resin had a peak molecular weight (Mp) of 12000 and a weight-average molecular weight (Mw) of 15000.(Preparation of Amorphous Polyester Resin Particle Dispersion)

[0177] The following components were placed in a separable flask, thoroughly mixed and dissolved, and then while stirring and heating at 40°C, ion-exchanged water was added dropwise at a liquid feed rate of 8 g / minute using a liquid feed pump. Amorphous polyester resin 200.00 parts by mass Methyl ethyl ketone 100.00 parts by mass Isopropyl alcohol 35.00 parts by mass 10% by mass aqueous ammonia solution 7.00 parts by mass

[0178] After the mixed solution became uniformly cloudy, the liquid feed rate was increased to 15 g / min to cause phase inversion, and the dropwise addition was stopped when the liquid feed amount reached 580 parts by mass. Thereafter, the solvent is removed under reduced pressure to obtain an amorphous polyester resin particle dispersion. The volume mean particle diameter of the obtained amorphous polyester resin particles is measured using a particle size analyzer "Nanotrack Wave" (manufactured by MicrotracBEL Corp) and is found to be 216 nm, and the solid concentration in the dispersion of amorphous polyester resin particles is found to be 20% by mass.[Coloring Agent Particle Dispersion]

[0179] Ninety (90) parts by mass of sodium dodecyl sulfate was dissolved in 1600 parts by mass of ion-exchanged water with stirring. While stirring, 420 parts by mass of carbon black Regal 330R (manufactured by Cabot Corporation) was gradually added. Next, the mixture was subjected to a dispersion treatment using a stirring apparatus CLEARMIX (trade name) (manufactured by M Technique Co., Ltd) to prepare a coloring agent particle dispersion. The particle size of the colorant particles in the dispersion liquid was measured using a particle size distribution analyzer "Nanotrack Wave (trade name)" (manufactured by MicrotracBEL Corp), and the particles were found to be 117 nm.[Production of toner base particle 1]

[0180] Into a reaction vessel equipped with a stirrer, a temperature sensor, and a cooling tube, 300 parts by mass of the styrene-acrylic resin particle dispersion in terms of solid content and 2000 parts by mass of ion-exchanged water were charged. Thereafter, a 5 mol / liter aqueous sodium hydroxide solution was added to the reaction vessel to adjust the pH to 10. Thereafter, 40 parts by mass of the coloring agent dispersion in terms of solid content was added. Then, an aqueous solution prepared by dissolving 60 parts by mass of magnesium chloride in 60 parts by mass of ion-exchanged water was added at 30°C over 10 minutes under stirring. Thereafter, the system was allowed to stand for 3 minutes, then the temperature increase was started, the system was heated to 80°C over 60 minutes, and the particle growth reaction was continued while maintaining 80°C. In this state, the particle diameter of the associated particles was measured with "Multisizer 3" (trade name) (manufactured by Beckman Coulter, Inc). When the volume-based median diameter (D 50 ) reached 5.6 µm, 30 parts by mass of the dispersion liquid of the amorphous polyester resin particles in terms of solid content was added over 30 minute. When the supernatant of the reaction liquid became transparent, an aqueous solution containing 190 parts by mass of sodium chloride dissolved in 760 parts by mass of ion-exchanged water was added to stop the particle growth. Furthermore, the temperature was raised, and fusion of the particles was allowed to proceed by heating and stirring in a state of 90°C, and when the average circularity of the particles reached 0.950, the temperature was cooled to 30°C, to prepare a dispersion liquid of toner base particle. The average circularity of the particles was measured using "measurement apparatus" "FPIA 2100" (trade name) (manufactured by Sysmex Corporation). The measurement of the average circularity of the particles by "FPIA-2100" was performed with the number of HPF detections as 4000.

[0181] The obtained dispersion liquid of the toner base particle was subjected to solid-liquid separation with a centrifuge to form a wet cake of the toner base particle. Then, the obtained wet cake was washed with ion-exchanged water at 35°C using the centrifugal separator until the electric conductivity of the filtrate became 5µ S / cm. Thereafter, the wet cake was transferred to "Flash Jet Dryer" (trade name) (manufactured by Seishin Enterprise Co., Ltd) and dried until the water content became 0.5% by mass, to thereby produce toner base particle 1. The obtained toner base particle 1 had a volume-based median diameter (D 50 ) of 5.9 µm and an average circularity of 0.955.[Production of toner base particle 2](Preparation of Crystalline Polyester Resin Particle Dispersion)

[0182] The following components were placed in a three flask to prepare a mixed solution, and then the pressure in the container was reduced by a pressure reducing operation. 1,9- Nonanediol 300.00 parts by mass Dodecanedioic acid 250.00 parts by mass Titanium butoxide (Ti (OBu) 4 ) 3.50 parts by mass

[0183] Furthermore, a nitrogen gas was introduced into the three flask to turn the inside of the flask into an inert atmosphere, and the mixed solution was refluxed for 6 hours at 180°C with mechanical stirring. Thereafter, an unreacted monomer component was removed by distillation under reduced pressure, the temperature was gradually raised to 220°C, and the mixture was stirred for 12 hours. When the mixture became viscous, the mixture was cooled to obtain a crystalline polyester resin particle dispersion.

[0184] The weight-average molecular weight (Mw) of the crystalline polyester resin contained in the obtained crystalline polyester resin particle dispersion was 19500. The melting point of the crystalline polyester resin was 75°C. Note that the weight-average molecular weight (Mw) and the melting point were measured by the following methods.(Method for measuring weight-average molecular weight)

[0185] The weight-average molecular weight was calculated using a calibration curve of monodisperse polystyrene standard particles by gel permeation chromatography (GPC) measurement under the following conditions. The calibration curve was prepared by measiring 10 polystyrene standard particles (manufactured by Pressure Chemical Co., Ltd) satisfying the molecular weight of 6.00×10 2< , 2.10×10 3< , 4.00×10 3< , 1.75×10 4< , 5.10×10 4< , 1.10×10 5< , 3.90×10 5< , 8.60×10 5< , 2.00×10 6< , and 4.48×10 6< .

[0186] Note that a sample was added to tetrahydrofuran (THF) so as to have a concentration of 1 mg / mL, was subjected to dispersion treatment at room temperature for 5 minutes using an ultrasonic disperser, and was then treated with a filter having a pore size of 0.2 µm. device: GPC device "HLC-8220GPC" (manufactured by Tosoh Corporation) column: "TSKguardcolumn + TSKgel (R) SuperHZM-M3 series" (manufactured by Tosoh Corporation) Carrier solvent: tetrahydrofuran (THF) detector: differential refractive index detector (RI detector) Column temperature: 40°C Flow rate: 0.2 mL / min samples: 10µ L (method for measuring melting point)

[0187] A DSC curve was obtained using a differential scanning calorimeter "Diamond DSC" (manufactured by PerkinElmer, Inc) under measurement conditions (temperature increase / cooling conditions) including a first temperature increase process of increasing the temperature from 0°C to 200°C at an elevating rate of 10°C / min, a cooling process of cooling from 200°C to 0°C at a cooling rate of 10°C / min, and a second temperature increase process of increasing the temperature from 0°C to 200°C at a temperature increase rate of 10°C / min in this order with sample 3. 0 mg sealed in an aluminum pan and set in a holder, and an empty aluminum pan set as a reference. Then, based on this DSC curve, the endothermic peak top temperature derived from the sample in the first heating process was defined as the melting point.(Preparation of Amorphous Polyester Resin Particle Dispersion (2))(Preparation of Amorphous Polyester Resin (2))

[0188] The following monomers and a catalyst were placed in a heat-dried three flask, and then, the air in the container was depressurized by a depressurizing operation, an inert atmosphere was further provided with nitrogen gas, and the mixture was refluxed for 5 hours at 180°C with mechanical stirring. Bisphenol A propylene oxide 2100.00 parts by mass Bisphenol A ethylene oxide 1600.00 parts by mass 1,3,5-benzenetricarboxylic acid 55.00 parts by mass 1,2,4-benzenetricarboxylic acid 620.00 parts by mass terephthalic acid 730.00 parts by mass Fumaric acid 400.00 parts by mass Dibutyltin oxide 25.00 parts by mass

[0189] Thereafter, while the water produced in the reaction system was distilled off by vacuum distillation, the temperature was gradually raised to 240°C. Furthermore, the dehydration condensation reaction was continued at 240°C for 3 hours. When a viscous state was reached, the molecular weight was confirmed by gel permeation chromatography (GPC), and then the reaction was stopped. When the mass average molecular weight reached 36000, the distillation under reduced pressure was stopped to obtain an amorphous polyester resin (2).(Preparation of Amorphous Polyester Resin Particle Dispersion (2))

[0190] The following components were placed in a separable flask, thoroughly mixed and dissolved, and then while stirring and heating at 40°C, ion-exchanged water was added dropwise at a liquid feed rate of 8 g / minute using a liquid feed pump. Amorphous polyester resin (2) 200.00 parts by mass Methyl ethyl ketone 100.00 parts by mass Isopropyl alcohol 35.00 parts by mass 10% by mass aqueous ammonia solution 7.00 parts by mass

[0191] After the mixed solution became uniformly cloudy, the liquid feed rate was increased to 15 g / min to cause phase inversion, and the dropwise addition was stopped when the liquid feed amount reached 580 parts by mass. Thereafter, the solvent is removed under reduced pressure to obtain an amorphous polyester resin particle dispersion (2). When the volume mean particle diameter of the obtained amorphous polyester resin particles is measured using a particle size analyzer "Nanotrack Wave" (manufactured by MicrotracBEL Corp), it is 164 nm, and the solid concentration in the dispersion liquid of amorphous polyester resin particles (2) is 35% by mass.(Preparation of Coloring Agent Particle Dispersion)

[0192] The following components were mixed, stirred and dissolved. Sodium dodecyl sulfate 90.00 parts by mass ion-exchanged water 1600.00 parts by mass

[0193] While the obtained solution was stirred, the following components were gradually added thereto. carbon black "REGAL (R) 330R" (manufactured by Cabot Corporation) 420.00 parts by mass

[0194] Next, the mixture was subjected to dispersion treatment using a stirring apparatus CLEARMIX (manufactured by M Technique Co., Ltd) to prepare a coloring agent particle dispersion. The volume mean particle diameter of the obtained colorant particles was measured using a particle size analyzer "Nanotrack Wave" (manufactured by MicrotracBEL Corp), and the particles were found to be 117 nm.(Preparation of Release Agent Particle Dispersion)

[0195] The following components were mixed, and the release agent was dissolved at an internal liquid temperature of 120°C using a pressure discharge-type homogenizer (Gaulin homogenizer manufactured by Gaulin). Thereafter, the mixture was dispersed at a dispersion pressure of 5 MPa for 120 minutes and subsequently at 40 MPa for 360 minutes, and cooled to obtain a dispersion liquid. Paraffin wax "HNP0190" (manufactured by NIPPON SEIRO CO., LTD., melting point: 85°C) 270.00 parts by mass Anionic surfactant "NEOGEN (R) RK" (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., active ingredient 60%, 3% relative to release agent) 13.50 parts by mass ion-exchanged water 21.60 parts by mass

[0196] Ion-exchanged water was added to adjust the solid content concentration to 20% by mass, thereby obtaining a release agent particle dispersion. The volume mean particle diameter of the resulting release agent particles was measured using a particle size analyzer "Nanotrack Wave" (manufactured by MicrotracBEL Corp) and found to be 215 nm.(Aggregation-fusion step and aging step)

[0197] The following components were placed in a polymerization vessel equipped with a pH -meter, a stirring impeller, and a thermometer, and the mixture was stirred in a 140 rpm for 15 minutes to mix the surfactant with the dispersion (2) of amorphous polyester resin particles and the dispersion of crystalline polyester resin particles. Amorphous polyester resin particle dispersion (2): 100.00 parts by mass Crystalline polyester resin particle dispersion 12.80 parts by mass Anionic surfactants (20% by mass aqueous solutions of "DOWFAX (R) 2A1" (manufactured by Dow Toray Industries, Inc)) 4.10 parts by mass ion-exchanged water 250.00 parts by mass

[0198] Next, the following components were added and mixed, and then an aqueous nitrate solution of 0. 3M was added to adjust the pH level to 4.8. Coloring agent particle dispersion 15.00 parts by mass Release agent particle dispersion 12.00 parts by mass

[0199] Next, the following components were added dropwise as a coagulant while applying a shear force at a rotational speed of 4000 rpm using a homogenizer "ULTRA-TURRAX (R) Series" (manufactured by IKA). Note that during the dropwise addition of the coagulant (the following components), the viscosity of the raw material mixture rapidly increased, and therefore, at the time point when the viscosity increased, the dropwise addition rate was reduced to prevent the coagulant from being biased to one place. After the coagulant was added dropwise, the number of rotations was further increased to 5000 rpm and the mixture was stirred for 5 minutes to sufficiently mix the coagulant and the raw material mixture. 22.00 parts by mass of a 10 mass% aqueous nitric acid solution of aluminum sulfate

[0200] Next, the raw-material mixture was stirred at a rotational speed within a range of 400 to 600 rpm while being heated to 30°C with a mantle heater. After stirring for 10 minutes, formation of stable primary particles was confirmed using a precision particle size distribution analyzer "Coulter Multisizer 3" (manufactured by Beckman Coulter, Inc., aperture diameter: 100 µm), and then the temperature was increased to 46°C at a temperature increase rate of 0.1 °C / min in order to grow core particles. The growth of the core particles was confirmed at any time using a Coulter counter, and the aggregation temperature and the number of rotations of the stirring blade were appropriately adjusted according to the aggregation rate.

[0201] On the other hand, for the shell layer, the following components were mixed to prepare a binder resin particle dispersion for a shell layer, and the pH was set to 3.8. Amorphous polyester resin particle dispersion (2): 55.00 parts by mass ion-exchanged water 22.00 parts by mass Anionic surfactants (20% by mass aqueous solutions of "DOWFAX (R) 2A1" (manufactured by Dow Toray Industries, Inc)) 0.80 parts by mass

[0202] When the particle size of the core particles had grown to 5.2 µm in the above aggregation step, the previously prepared binder resin particle dispersion for shell layers was added, and the mixture was held for 10 minutes with stirring. Thereafter, in order to stop the growth of the coated (shell-layer-formed) core particles, the following components were added, and then an aqueous sodium hydroxide solution of 1M was added to adjust the pH level of the starting material mixture to 7.5. 20% by mass solution of EDTA (ethylenediaminetetraacetic acid) 0.80 parts by mass

[0203] Then, in order to fuse the coated core particles, the temperature was increased to 85°C at a temperature increase rate of 1°C / min while the pH was adjusted to 7.5. After reaching 85°C, the pH was adjusted to 7.5 in order to promote coalescence.

[0204] (Cooling Step) Thereafter, when the average circularity reached 0.965 using a flow particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation), the mixture was rapidly cooled at a temperature lowering rate of 10°C / min to obtain toner base particle dispersion 2.(filtration / washing step and drying step)

[0205] The obtained toner base particle dispersion 2 was filtered and sufficiently washed with ion-exchanged water. Then, the resultant was dried at 40°C to obtain toner base particle 2. The resulting toner base particle 2 had a volume-based median diameter of 6.1 µm and an average circularity of 0.954. The toner base particle 2 is toner base particle for use in the toner in Example 23.[Preparation of toner 1]

[0206] Silica particle 1, which is an inorganic fine particle, was added as an external additive to the "toner base particle 1" prepared as described above. The content of the silica particle 1 was 1.1 parts by mass relative to 100 parts by mass of the content of the toner base particle 1. Next, the mixture of the toner base particle 1 and the silica particles 1 was loaded into a Henschel mixer "Model: FM20C / I" (product of Nippon Coke & Engineering Co., Ltd). Then, the number of rotations was set so that the peripheral speed of the blade tip became 50 m / s, and the mixture was stirred for 20 minutes to prepare "toner 1" containing toner base particle 1 and silica particles 1.

[0207] The temperature of the mixture during stirring of the mixture with the Henschel mixer was set to 40°C ± 1°C. When the temperature reached 41°C, cooling water was passed through the outer bath of the Henschel mixer at a flow rate of 5 L / minute. When the temperature reached 39°C, cooling water was allowed to flow at a rate of 1 L / min to control the temperature inside the Henschel mixer.(free component)

[0208] A free component was separated from the toner, and the weight-average molecular weight, the number-average molecular weight, and the content of the free component were determined.(separation of free component)

[0209] The free component was separated from the toner by the following separation method. First, the toner 3 g was placed in a 50 mL screw-cap bottle, wetted with methanol 40 g, and stirred. Then, the mixture was transferred to a 60 mL disposable cup, and the tip φ36 of an ultrasound transducer was adjusted with an ultrasound homogeniser "US-1200T" (manufactured by NISSEI Corporation) so as to be immersed in the liquid to the extent of 3 cm. Thereafter, the ultrasound energy was adjusted to 100 W, and ultrasound waves were applied for 1 minute to obtain a dispersion liquid. The resulting dispersion liquid was transferred to a 15 mL tube and allowed to stand overnight, and then the supernatant was collected. The operation of collecting the supernatant liquid from the toner 3 g was repeated 50 times. The entire amount of the collected supernatant was concentrated to dryness. The solid obtained by concentration to dryness was refluxed with methyl ethyl ketone, and the methyl ethyl ketone-soluble matter was removed to obtain a solid sample. Specifically, after the refluxing, a solid content was separated by ultra-cooling centrifugation to obtain a solid content sample. The ultra-cold centrifugation was performed under conditions of a temperature of 10°C and a rotational speed of 50000 rpm. As a measurement apparatus for the ultra-cooling separation, himac CS150NX (trade name) (manufactured by Eppendorf - Himac Technologies) was used. The resulting solids samples were weighed into glass 50 mL centrifuge tubes. Then, chloroform 20 mL was put in the centrifugal tube, ultrasound waves were applied for 10 minutes using the ultrasound homogeniser, and centrifugal separation was performed for 10 minutes in a 3500 rpm. The transparent supernatant obtained by centrifugation was transferred to a 100 mL eggplant-shaped flask and dried under reduced pressure. The solid matter obtained by drying under reduced pressure was subjected to the above-described operation again from the above-described "putting in a glass 50 mL centrifuge tube and weighing" to obtain a free component.(weight-average molecular weight of free component)

[0210] The weight-average molecular weight of the free component was calculated by performing GPC measurement under the following conditions and using a calibration curve of standard polystyrene and N-hexylbenzene. For the GPC measurement of the free component, the free component 2 mg was weighed, 2 mL toluene was added dropwise, and the mixture was filtered through a filter having a pore size of 0.2 µm to prepare a sample solution for the GPC measurement. The conditions for the GPC measurement of the free component were as follows. GPC measurement apparatus: HLC-8420GPC (manufactured by Tosoh Corporation) column: Shodex K-806M (manufactured by Resonac Corporation) Column temperature: 45°C Carrier solvent: HPLC toluene Carrier solvent speed: 1.0mL / min Sample solution: 200µ L detector: differential refractive index detector (RI detector)

[0211] The calibration curves are prepared by measuring 11 standard polystyrenes (manufactured by Agilent Technologies) and N-hexylbenzene (manufactured by Tokyo Chemical Industry Co., Ltd) each having a 5.80 × 10 2< , 1.25 × 10 3< , 4.91 × 10 3< , 9.82 × 10 3< , 2.29 × 10 4< , 6.76 × 10 4< , 2.17 × 10 5< , 5.37 × 10 5< , 9.20 × 10 5< , 3.15 × 10 6< , 6.57 × 10 6< molecular weight.(number-average molecular weight of free component)

[0212] The number-average molecular weight of the free component was measured by the same method as the method for measuring the weight-average molecular weight described above, and was obtained by calculating the number average instead of the weight average.(content of free component in toner)

[0213] The content of the free component in the toner is "the amount of the free component extracted from the toner" with respect to "the amount of the entire toner", and is represented by the mass (mg) of the free component in the toner 1 kg. The content of the free component in the toner was determined using the free component obtained by the method of "separation of free component" described above. Since the free component obtained by the method of the above-described "separation of free component" may contain impurities, the accurate content of the free component was determined by performing GPC measurement. Then, the content (mg / kg) of the free component in the toner was obtained by expressing the value of the mass obtained by GPC measurement of the obtained free component with respect to the mass of the toner used in the above-described method of "separation of free component" by the mass (mg) of the free component in the toner 1 kg. The content of the free component was obtained by GPC measurement under the following conditions using polydimethylsiloxane as a standard product. Specifically, a polydimethylsiloxane solution having a known concentration was subjected to GPC measurement under the following conditions, and the polydimethylsiloxane was obtained by an absolute calibration curve method using the polydimethylsiloxane as a standard. As the polydimethylsiloxane, a commercially available product (Sigma -Aldrich 181846-25G, manufactured by Buchi Co) was used. GPC measurement apparatus: HLC-8420GPC (manufactured by Tosoh Corporation) column: Shodex K-806M (manufactured by Resonac Corporation) Column temperature: 45°C Carrier solvent: HPLC toluene Carrier solvent speed: 1.0mL / min Sample solution: 200µ L detector: differential refractive index detector (RI detector) (free component content in silica)

[0214] The "content of free components in silica", which is the content of free components in the inorganic fine particles, was measured by the same method as the method for measuring the "content of free components in toner". The method for taking out the free component from the silica particles or the titania particles is as follows. The prepared silica particles or titania particles were placed in a glass 50 mL centrifuge tube and subjected to 0. 8 g weighing. Next, the chloroform 20 mL was put in the centrifugation tube, and ultrasound waves were applied for 10 minutes using the ultrasound homogeniser. Thereafter, centrifugation was performed in a 3500 rpm for 10 minutes. The transparent supernatant obtained by centrifugation was transferred to a 100 mL eggplant-shaped flask and dried under reduced pressure. The solid matter obtained by drying under reduced pressure was subjected to the above-described operation again from the above-described "putting in a glass 50 mL centrifuge tube and weighing" to obtain a free component. The obtained free component was subjected to GPC measurement to determine the accurate amount of the free component, and the accurate amount of the free component relative to the amount of the silica particles used for obtaining the free component was expressed in terms of the mass (mg) of the free component in the silica 1 kg to obtain the content (mg / kg) of the free component in the silica.[Production of carrier](Production of carrier Core Material Particle 1)

[0215] MnO: 35mol%, MgO: 14.5 mol%, Fe 2 O 3 :50mol% and SrO: The raw materials were weighed so as to be 0.5 mol%, mixed with water, and then pulverized with a wet media mill for 5 hours to obtain slurry. The obtained slurry was dried with a spray dryer to obtain truly spherical particles. The particles are classified to adjust the particle size, Pre-baking was performed by heating at 950°C for 2 hours. The resultant was pulverized for 1 hour with a wet ball-mill using stainless steel beads having a size of 0. 3 cm, and then further pulverized for 4 hours using zirconia beads having a size of 0. 5 cm. Polyvinyl alcohol (PVA) was added as a binder in an amount of 0.8 parts by mass relative to 100 parts by mass of the solid content, then granulated and dried by a spray dryer, and held in an electric furnace at a temperature of 1350°C for 5 hours to perform main firing. Thereafter, the resultant was disintegrated, further classified to adjust the particle size, and then subjected to magnetic separation to separate a low-magnetic product, thereby obtaining carrier core material particles 1. The particle diameter of the carrier core material particle 1 was 35 µm.(Production of Coating Material 1)

[0216] Cyclohexyl methacrylate and methyl methacrylate were added to a 0.3% by mass aqueous sodium benzene sulfonate solution. At this time, the mass ratio of cyclohexyl methacrylate to methyl methacrylate was set as "5:5". This "5:5" is the copolymerization ratio. Then, potassium persulfate was added in an amount corresponding to 0.5 parts by mass with respect to 100 parts by mass of the total amount of the monomers, and emulsion polymerization was performed to obtain a reaction liquid. Next, the obtained reaction liquid was dried by spray drying, thereby producing a "coating material 1". The weight-average molecular weight of the obtained coating material 1 was 500000. The coating material is a resin for coating a core material.(Production of carrier 1)

[0217] The high-speed stirring mixer equipped with a horizontal stirring blade was charged with 100 parts by mass of the "carrier core material particles 1" as core material particles and 4.5 parts by mass of the "coating material 1" as a core material coating resin. Next, the materials were mixed and stirred at 22°C for 15 minutes under conditions in which the circumferential speed of the horizontal rotary wings was 8 m / s. Thereafter, the materials were mixed and stirred at 120°C for 50 minutes to coat the surfaces of the core material particles with the coating material by the action of mechanical impact force (mechanochemical method), thereby producing "carrier 1".(Production of Coating Material 2)

[0218] Styrene and methyl methacrylate were added to an aqueous solution of 0.3% by mass of sodium benzene sulfonate. At this time, the mass ratio of styrene and methyl methacrylate was set as "5:5". This "5:5" is the copolymerization ratio. Then, potassium persulfate was added in an amount corresponding to 0.5 parts by mass with respect to 100 parts by mass of the total amount of the monomers, and emulsion polymerization was performed to obtain a reaction liquid. Next, the obtained reaction liquid was dried by spray drying, thereby producing a "coating material 2". The weight-average molecular weight of the obtained coating material 2 was 450,000.(Production of carrier 2)

[0219] Into the high-speed stirring mixer equipped with a horizontal stirring blade, 100 parts by mass of the "carrier core material particles 1" as core material particles and 4.5 parts by mass of the "coating material 2" as a core material coating resin were charged. Next, the materials were mixed and stirred at 22°C for 15 minutes under conditions in which the circumferential speed of the horizontal rotary wings was 8 m / s. Thereafter, the materials were mixed and stirred at 120°C for 50 minutes to coat the surfaces of the core material particles with the coating material by the action of mechanical impact force (mechanochemical method), thereby producing "carrier 2".(Preparation of Developer)

[0220] The toner and the carrier produced as described above were mixed so that the toner concentration was 6% by mass, to produce a developer (Example 1). The mixture was mixed for 30 minutes using a V-type mixer. Developers (Examples 2 to 32 and Comparative Examples 1 to 4) were produced in the same manner as in Example 1 except that the conditions of the type of the external additive, the type and amount of surface modification, the type of the toner base particle and content of the inorganic fine particles, the type of the carrier, and the free component were changed as described in Table II. The obtained developer was evaluated as follows.<Evaluation method >

[0221] A commercially available multifunction peripheral "bizhub Pro C14000 (trade name) (manufactured by Konica Minolta, Inc)" was used to evaluate developing leakage and density fluctuation after endurance.[Developing Leakage]

[0222] In a printing environment of ordinary temperature and ordinary humidity (20°C, 50% RH), after printing of 250000 sheets of a character image with a print coverage of 5% was finished, the developing bias was set so that the adhesion amount became 4.0 g / m 2< . Thereafter, a solid image was output, and it was confirmed whether obvious leakage occurred. The developing bias was increased to the negative voltage side one by one, the presence or absence of the occurrence of leakage was similarly confirmed by the solid image, and the voltage Δ V which is the difference between the lowest developing bias at which leakage occurred and the initial developing bias was compared. A Δ V of 200 V or more was considered to be acceptable.(evaluation criterion)

[0223] A: Δ V is greater than or equal to 400 V B: Δ V is greater than or equal to 300 V and less than 400 V, and C: Δ V is greater than or equal to 200 V and less than 300 V, and D: Δ V is less than 200 V [Density Fluctuation]

[0224] In a printing environment of normal temperature and normal humidity (20°C and 50% RH), after printing of a character image having a print coverage of 50% on 1000 sheets was completed, the image density difference between the first sheet and the 1000 th sheet was evaluated. The evaluation was performed for each solid image of a cyan single color (C) and green (G). The image density of the output image was measured using "Spectrolina / Scan Bundle (trade name) (manufactured by Gretag Macbeth)" under the following conditions. An image density difference was calculated from the obtained image density. An image density difference of 0.20 or less was determined to be acceptable.(Measurement Condition)

[0225] light source: D50 light source observation field of view: 2 ° density: ANSI T white reference: Abs filter: UV Cut Measurement mode: reflectance language: Japanese The difference in the solid image density ID was calculated for each of cyan (C) and green (G). (evaluation criterion)

[0226] A: Image density difference is 0.00 to 0.04 B: Image density difference of 0.05 to 0.10 C: Image density difference is 0.11 to 0.20 D: Image density difference is 0.21 or more

[0227] The evaluation results are shown in Table III.[Table 3]

[0228] TABLE III EVALUATION DEVELOPING LEAKAGE DENSITY FLUCTUATION EVALUATION RESULTS MEASUREMENT VALUE (V) EVALUATION RESULTS MEASUREMENT VALUE C G EXAMPLE 1 A 400 A 0.01 0.02 EXAMPLE 2 A 450 A 0.01 0.02 EXAMPLE 3 A 450 A 0.01 0.02 EXAMPLE 4 B 350 B 0.03 0.04 EXAMPLE 5 B 300 B 0.10 0.10 EXAMPLE 6 C 250 C 0.14 0.17 EXAMPLE 7 C 200 C 0.15 0.19 EXAMPLE 8 C 200 C 0.18 0.20 EXAMPLE 9 C 250 C 0.13 0.15 EXAMPLE 10 B 300 B 0.09 0.10 EXAMPLE 11 C 200 B 0.09 0.10 EXAMPLE 12 B 350 B-C 0.10 0.11 EXAMPLE 13 A 450 B 0.08 0.08 EXAMPLE 14 A 450 A 0.02 0.03 EXAMPLE 15 A 400 A-B 0.03 0.05 EXAMPLE 16 B 350 B 0.09 0.10 EXAMPLE 17 C 250 C 0.13 0.13 EXAMPLE 18 C 250 A 0.04 0.04 EXAMPLE 19 A 400 A 0.02 0.02 EXAMPLE 20 A 400 A 0.04 0.05 EXAMPLE 21 B 350 B 0.08 0.10 EXAMPLE 22 B 300 B-C 0.10 0.12 EXAMPLE 23 C 250 C 0.13 0.15 EXAMPLE 24 B 300 B-C 0.10 0.11 EXAMPLE 25 C 200 C 0.18 0.19 EXAMPLE 26 A 450 A 0.01 0.02 EXAMPLE 27 A 450 A 0.01 0.01 EXAMPLE 28 C 200 C 0.15 0.19 EXAMPLE 29 C 200 B 0.08 0.09 EXAMPLE 30 B 300 B 0.07 0.06 EXAMPLE 31 B 350 B-C 0.10 0.12 EXAMPLE 32 B 350 C 0.15 0.17 COMPARATIVE EXAMPLE 1 D 150 D 0.22 0.25 COMPARATIVE EXAMPLE 2 D 150 D 0.21 0.21 COMPARATIVE EXAMPLE 3 D 150 D 0.22 0.25 COMPARATIVE EXAMPLE 4 C 200 D 0.21 0.24

[0229] In Table III, in a case where the measurement values of the density fluctuation of C and G are different evaluation results, the measurement values are between the both evaluation results. For example, in example 12, since C is evaluated as B and G is evaluated as C, the evaluation result is "B-C" in the sense that the evaluation result is between these evaluations.

[0230] From Table III, it is found that in example, the weight-average molecular weight of the free component is 1000 or more and 20000 or less and the content of the free component is 2 mg / kg or more and 700 mg / kg or less, so that the developing leakage is suppressed and the density fluctuation is small. In comparative example 1, since the weight-average molecular weight of the free component is too large, the density fluctuation is large. Comparative Example 1 also has large developing leakage. In comparative example 2, since the weight-average molecular weight of the free component is too small, the developing leakage is large. In comparative example 2, the density fluctuation is large. In comparative example 3, the free component content (mg / kg) in the toner is excessively low, and thus the developing leakage is great. In comparative example 3, the density fluctuation is large. In comparative example 4, the free component content (mg / kg) in the toner is excessively large, and therefore, the density fluctuation is large.

[0231] Although embodiments of the present invention have been described and illustrated in detail, the disclosed embodiments are made for purposes of illustration and example only and not limitation. The scope of the present invention should be interpreted by terms of the appended claims.

Claims

1. An electrostatic charge image developing toner comprising a toner base particle and an external additive, wherein the external additive includes at least an inorganic fine particle, the inorganic fine particle has a surface modifying agent on a surface thereof, the electrostatic charge image developing toner includes a free component, a weight-average molecular weight of the free component is 1000 or more and 20000 or less, a content of the free component is 2 mg / kg or more and 700 mg / kg or less, and the free component is a chloroform extract from a methyl ethyl ketone insoluble matter extracted from the electrostatic charge image developing toner with methanol.

2. The electrostatic charge image developing toner according to claim 1, wherein a value of Mw / Mn is 1 or more and 3 or less, where Mw is the weight-average molecular weight of the free component and Mn is a number-average molecular weight of the free component.

3. The electrostatic charge image developing toner according to claim 1, wherein the free component has a weight-average molecular weight of 1000 or more and 10000 or less.

4. The electrostatic charge image developing toner according to claim 1, wherein the content of the free component is 2 mg / kg or more and 500 mg / kg or less.

5. The electrostatic charge image developing toner according to claim 1, wherein the surface modifying agent is a silicone oil.

6. The electrostatic charge image developing toner according to claim 1, wherein the inorganic fine particle is a silica particle.

7. A developer, which is a mixture of the electrostatic charge image developing toner according to any one of claims 1 to 6 and a carrier.

8. An image forming method comprising a developing step of performing developing using the electrostatic charge image developing toner according to any one of claims 1 to 6.

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