Toner for developing electrostatic images, electrostatic image developer, toner cartridge, process cartridge, image forming apparatus, and image forming method

Abstract

The present invention relates to a toner for developing electrostatic images, an electrostatic image developer, a toner cartridge, a process cartridge, an image forming apparatus, and an image forming method. The toner for developing electrostatic images comprises toner particles, layered compound particles, and inorganic particles, wherein the proportion of irregularly shaped inorganic particles having a circularity of 0.5 to 0.9 and a particle size of 0.015 μm to 0.350 μm is 2% by number to 70% by number relative to the total amount of the inorganic particles.

Description

Technical Field

[0001] The present invention relates to a toner for developing an electrostatic image, an electrostatic image developer, a toner cartridge, a process cartridge, an image forming apparatus, and an image forming method. Background Art

[0002] Japanese Patent Application Laid-Open No. 2006-317489 discloses a toner in which 0.1 to 2.0 parts by weight of melamine cyanurate powder having a volume average particle size of 3 to 9 μm is added to a base toner having an average circularity of 0.94 to 0.995 and a volume average particle size of 3 to 9 μm, based on 100 parts by weight of the base toner.

[0003] Japanese Patent Application Laid-Open No. 2009-237274 discloses a positively chargeable toner comprising colored resin particles comprising a binder resin, a colorant, and a positive charge control agent, to which is added 0.01 to 0.5 parts by weight of melamine cyanurate particles having a number-average primary particle size of 0.05 μm to 1.5 μm per 100 parts by weight of the colored resin particles. Summary of the Invention

[0004] Technical problem to be solved by the invention

[0005] The technical problem to be solved by the present invention is to provide a toner for electrostatic image development. Compared with a toner for electrostatic image development that contains toner particles, layered structure compound particles and inorganic particles and has a roundness of greater than 0.5 and less than 0.9 and a particle size of greater than 0.015 μm and less than 0.350 μm, in which the proportion of irregular inorganic particles relative to the total inorganic particles is less than 2% or greater than 70%. The toner for electrostatic image development of the present invention can suppress offset when the toner image is fixed to a recording medium.

[0006] Means for solving technical problems

[0007] According to the first embodiment of the present invention, a toner for electrostatic image development is provided, which comprises toner particles, layered structure compound particles and inorganic particles, wherein the proportion of irregular inorganic particles having a roundness of not less than 0.5 and not more than 0.9 and a particle size of not less than 0.015 μm and not more than 0.350 μm relative to the above-mentioned inorganic particles as a whole is not less than 2% by number and not more than 70% by number.

[0008] According to the second aspect of the present invention, the ratio of the irregular-shaped inorganic particles to the entire inorganic particles is 20% by number or more and 65% by number or less.

[0009] According to the third aspect of the present invention, the mass-based ratio Ma / Mb of the content Ma of the layered structure compound particles to the content Mb of the irregular-shaped inorganic particles is 0.004 or more and 1.0 or less.

[0010] According to a fourth aspect of the present invention, the ratio Ma / Mb is not less than 0.05 and not more than 0.6.

[0011] According to the fifth aspect of the present invention, the content of the layered structure compound particles is 0.01% by mass or more and 2.0% by mass or less based on the total mass of the electrostatic image developing toner.

[0012] According to a sixth aspect of the present invention, the irregular-shaped inorganic particles are irregular-shaped silica particles.

[0013] According to a seventh aspect of the present invention, the layered compound particles include at least one selected from the group consisting of melamine cyanurate particles, boron nitride particles, graphite fluoride particles, molybdenum disulfide particles, and mica particles.

[0014] According to an eighth aspect of the present invention, there is provided an electrostatic image developer comprising the above-mentioned electrostatic image developing toner.

[0015] According to a ninth aspect of the present invention, there is provided a toner cartridge that is detachably mounted in an image forming apparatus and stores the above-mentioned toner for developing an electrostatic image.

[0016] According to the tenth aspect of the present invention, there is provided a processing cartridge that is detachably mounted in an image forming apparatus and includes a developing mechanism that stores the electrostatic image developer and develops the electrostatic image formed on the surface of an image retaining member into a toner image using the electrostatic image developer.

[0017] According to an eleventh aspect of the present invention, there is provided an image forming apparatus comprising:

[0018] Image holding body;

[0019] a charging mechanism for charging the surface of the image holding member;

[0020] an electrostatic image forming mechanism for forming an electrostatic image on the charged surface of the image holding member;

[0021] a developing mechanism storing the electrostatic image developer and developing the electrostatic image formed on the surface of the image holding member into a toner image using the electrostatic image developer;

[0022] a transfer mechanism for transferring the toner image formed on the surface of the image holding member to the surface of a recording medium; and

[0023] The fixing mechanism fixes the toner image transferred to the surface of the recording medium.

[0024] According to a twelfth aspect of the present invention, there is provided an image forming method comprising:

[0025] Charging, charging the surface of the image holding body;

[0026] Electrostatic image formation, forming an electrostatic image on the charged surface of the image holding member;

[0027] developing the electrostatic image formed on the surface of the image holding member into a toner image using the electrostatic image developer;

[0028] Transferring the toner image formed on the surface of the image holding member to the surface of a recording medium; and

[0029] Fixing is to fix the toner image transferred to the surface of the recording medium.

[0030] Effects of the Invention

[0031] According to the above-mentioned scheme 1, 6 or 7, a toner for electrostatic image development is provided. Compared with a toner for electrostatic image development containing toner particles, layered structure compound particles and inorganic particles, wherein the proportion of irregular inorganic particles with a roundness of not less than 0.5 and not more than 0.9 and a particle size of not less than 0.015 μm and not more than 0.350 μm relative to the total inorganic particles is less than 2% or more than 70%. The toner for electrostatic image development of this scheme can suppress contamination when the toner image is fixed to a recording medium.

[0032] According to the above-mentioned second scheme, a toner for electrostatic image development is provided. Compared with a toner for electrostatic image development in which the ratio of irregular inorganic particles to the total inorganic particles is less than 20% or greater than 65%, the toner for electrostatic image development of this scheme can suppress the contamination when the toner image is fixed to the recording medium.

[0033] According to the third embodiment, a toner for developing an electrostatic image is provided, which can suppress the deterioration of the toner image when fixing the toner image to the recording medium, compared with a toner for developing an electrostatic image in which the mass basis ratio Ma / Mb of the content Ma of the layered structure compound particles to the content Mb of the irregular inorganic particles is less than 0.004 or greater than 1.0.

[0034] According to the fourth embodiment, a toner for developing an electrostatic image is provided, which can suppress the deterioration of the toner image when the toner image is fixed to the recording medium, compared with a toner for developing an electrostatic image in which the mass basis ratio Ma / Mb of the content Ma of the layered structure compound particles to the content Mb of the irregular inorganic particles is less than 0.05 or greater than 0.6.

[0035] According to the fifth embodiment, a toner for developing an electrostatic image is provided, which can suppress offset when fixing a toner image to a recording medium, compared to an electrostatic image developing toner having a content of layered structure compound particles of less than 0.01% by mass or greater than 2.0% by mass relative to the entire electrostatic image developing toner.

[0036] According to the above-mentioned eighth embodiment, an electrostatic image developer is provided. Compared with a case where the electrostatic image developing toner contains toner particles, layered structure compound particles and inorganic particles, and the proportion of irregular inorganic particles having a roundness of not less than 0.5 and not more than 0.9 and a particle size of not less than 0.015 μm and not more than 0.350 μm relative to the total inorganic particles is less than 2% by number or greater than 70% by number, the electrostatic image developer of this embodiment can suppress contamination when the toner image is fixed to a recording medium.

[0037] According to the above-mentioned ninth scheme, a toner cartridge is provided, which can suppress contamination when fixing a toner image to a recording medium, compared with a case where a toner for electrostatic image development contains toner particles, layered structure compound particles and inorganic particles, and the proportion of irregular inorganic particles with a roundness of not less than 0.5 and not more than 0.9 and a particle size of not less than 0.015 μm and not more than 0.350 μm relative to the total inorganic particles is less than 2% or more than 70%.

[0038] According to the above-mentioned scheme 10, a processing box is provided, which can suppress contamination when fixing the toner image to the recording medium, compared with the case where the toner for electrostatic image development contains toner particles, layered structure compound particles and inorganic particles, and the proportion of the irregular inorganic particles with a roundness of not less than 0.5 and not more than 0.9 and a particle size of not less than 0.015 μm and not more than 0.350 μm relative to the total inorganic particles is less than 2% or more than 70%.

[0039] According to the above-mentioned 11th scheme, an image forming device is provided. Compared with the case where the toner for electrostatic image development contains toner particles, layered structure compound particles and inorganic particles, and the proportion of irregular inorganic particles with a roundness of not less than 0.5 and not more than 0.9 and a particle size of not less than 0.015 μm and not more than 0.350 μm relative to the total inorganic particles is less than 2% or more than 70%. The image forming device of this scheme can suppress the contamination when the toner image is fixed to the recording medium.

[0040] According to the above-mentioned scheme 12, an image forming method is provided, which can suppress contamination when the toner image is fixed to a recording medium, compared with a case where the toner for electrostatic image development contains toner particles, layered structure compound particles and inorganic particles, and the proportion of irregular inorganic particles with a roundness of not less than 0.5 and not more than 0.9 and a particle size of not less than 0.015 μm and not more than 0.350 μm relative to the total inorganic particles is less than 2% or more than 70%. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a schematic structural diagram showing an example of the image forming apparatus according to the present embodiment.

[0042] Figure 2 This is a schematic structural diagram showing an example of a process cartridge that is attached to and detached from the image forming apparatus according to the present embodiment. DETAILED DESCRIPTION

[0043] The following describes embodiments of the present invention. These descriptions and examples are provided to illustrate the embodiments and are not intended to limit the scope of the embodiments.

[0044] In the present invention, the numerical range expressed using “to” indicates a range including the numerical values described before and after “to” as the minimum value and the maximum value, respectively.

[0045] In the numerical range described in stages in the present invention, the upper limit or lower limit described in one numerical range can be replaced by the upper limit or lower limit of the numerical range in other stages described. In addition, in the numerical range described in the present invention, the upper limit or lower limit of the numerical range can be replaced by the value shown in the embodiments.

[0046] The term "step" in the present invention includes not only an independent step but also a step that cannot be clearly distinguished from other steps as long as the intended purpose of the step can be achieved.

[0047] While the embodiments of the present invention are described with reference to the drawings, the configuration of the embodiments is not limited to that shown in the drawings. In addition, the sizes of the components in the drawings are schematic, and the relative sizes of the components are not limited thereto.

[0048] Each component in the present invention may contain two or more corresponding substances. When referring to the amount of each component in the composition of the present invention, if there are two or more substances corresponding to each component in the composition, unless otherwise stated, the amount refers to the total amount of the two or more substances present in the composition.

[0049] The particles corresponding to each component in the present invention may include two or more types. When two or more types of particles corresponding to each component are present in the composition, the particle size of each component refers to the value for the mixture of the two or more types of particles present in the composition unless otherwise stated.

[0050] In the present invention, the “toner for developing an electrostatic image” is also simply referred to as the “toner,” and the “developer for developing an electrostatic image” is also simply referred to as the “developer.”

[0051] <Toner for Electrostatic Image Development>

[0052] The toner of this embodiment includes toner particles, layered compound particles, and inorganic particles. The proportion of irregular inorganic particles having a circularity of 0.5 to 0.9 and a particle size of 0.015 μm to 0.350 μm is 2% to 70% by number relative to the total inorganic particles.

[0053] In the present invention, inorganic particles having a circularity of 0.5 to 0.9 and a particle size of 0.015 μm to 0.350 μm are referred to as irregular-shaped inorganic particles.

[0054] The toner of this embodiment can suppress offset when fixing a toner image to a recording medium. The mechanism is presumed to be as follows.

[0055] Toners containing added layered compound particles (e.g., melamine cyanurate particles and boron nitride particles) are well known. Layered compound particles are particles of a compound having a layered structure with interlayer distances on the order of angstroms, and are believed to exhibit a lubricating effect through interlayer slip. Layered compound particles added to toners act as a lubricant, for example, at the contact point between the image support and the cleaning blade.

[0056] However, when forming an image using a toner to which layered compound particles are added, staining (a phenomenon in which the toner image adheres to the fixing component and peels off from the recording medium) may occur when the toner image is fixed to a recording medium. This staining is believed to occur because the layered compound particles are less likely to be released from the toner particles than other lubricant particles (e.g., fatty acid metal salts) and are more likely to be transported to the fixing mechanism while attached to the toner particles. It is speculated that the layered compound particles, which are transported to the fixing mechanism while attached to the toner particles, release the fixing pressure applied by the fixing mechanism to the toner image on the recording medium in the direction of the surface of the recording medium due to their lubricating effect, resulting in insufficient fixing of the toner image on the recording medium, resulting in staining. This staining is significant when forming high-density images in a high-temperature, high-humidity environment, where the release of the layered compound particles from the toner particles is suppressed.

[0057] In contrast, it is speculated that using the toner of this embodiment, in which the ratio of irregular-shaped inorganic particles is limited to the above range, ensures friction between the fixing mechanism and the toner image on the recording medium. Therefore, the fixing pressure applied by the fixing mechanism is effectively transmitted to the toner image on the recording medium, thereby suppressing offset. If the ratio of irregular-shaped inorganic particles to the total number of inorganic particles is less than 2% by number, friction between the fixing mechanism and the toner image is difficult to achieve. If the ratio is 70% by number or greater, the toner image is more likely to adhere to the fixing mechanism. Therefore, the ratio of irregular-shaped inorganic particles is preferably between 2% and 70%.

[0058] The reasons for limiting the circularity and particle size of irregular-shaped inorganic particles to the above ranges are as follows. If the circularity of the inorganic particles is too low, they are difficult to release from the toner particles, making it difficult to achieve the intended effect of the inorganic particles on the image holder surface (e.g., abrasive effect on the image holder surface). If the circularity of the inorganic particles is too high, it is difficult to achieve friction between the fixing mechanism and the toner image. Therefore, the circularity of the irregular-shaped inorganic particles is 0.5 to 0.9. If the inorganic particles are too small, they are buried in the toner particles, making it difficult to achieve friction between the fixing mechanism and the toner image. If the inorganic particles are too large, the bonding area between the fixing mechanism and the toner image is reduced, and the thermal conductivity from the fixing mechanism is reduced. Therefore, the particle size of the irregular-shaped inorganic particles is 0.015 μm to 0.350 μm.

[0059] The composition, structure, and characteristics of the toner according to this embodiment will be described in detail below.

[0060] [Toner particles]

[0061] The toner particles contain, for example, a binder resin and, if necessary, a colorant, a release agent, and other additives.

[0062] - Adhesive resin -

[0063] Examples of the adhesive resin include vinyl resins formed from homopolymers of the following monomers or copolymers formed by combining two or more of these monomers: styrenes (e.g., styrene, p-chlorostyrene, α-methylstyrene, etc.), (meth)acrylates (e.g., methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (e.g., acrylonitrile, methacrylonitrile, etc.), vinyl ethers (e.g., vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (e.g., vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), olefins (e.g., ethylene, propylene, butadiene, etc.), and the like.

[0064] Examples of the adhesive resin include non-vinyl resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and modified rosin; mixtures of these resins with the above-mentioned vinyl resins; and graft polymers obtained by polymerizing vinyl monomers in the presence of these resins.

[0065] These adhesive resins may be used alone or in combination of two or more.

[0066] As the adhesive resin, polyester resin is suitable.

[0067] Examples of the polyester resin include known amorphous polyester resins. Among the polyester resins, an amorphous polyester resin and a crystalline polyester resin may be used in combination. The crystalline polyester resin is preferably used in an amount of 2% by mass to 40% by mass (preferably 2% by mass to 20% by mass) relative to the total binder resin.

[0068] The "crystallinity" of a resin means that there is no step-like change in endothermic value in differential scanning calorimetry (DSC) and that the resin has a clear endothermic peak. Specifically, it means that the half-value width of the endothermic peak is within 10°C when measured at a heating rate of 10 (°C / min).

[0069] On the other hand, the "amorphous" nature of a resin means that the half-value width is larger than 10°C, the resin exhibits a step-like change in endothermic value, or no clear endothermic peak is observed.

[0070] Amorphous polyester resin

[0071] Examples of the amorphous polyester resin include polycondensates of polycarboxylic acids and polyols. A commercially available amorphous polyester resin may be used, or a synthetic amorphous polyester resin may be used.

[0072] Examples of polycarboxylic acids include aliphatic dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, and sebacic acid), alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic acid), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, phthalic acid, and naphthalene dicarboxylic acid), and anhydrides or lower (e.g., C1-5) alkyl esters thereof. Among these, aromatic dicarboxylic acids are preferred as polycarboxylic acids.

[0073] Among the polycarboxylic acids, dicarboxylic acids and trivalent or higher carboxylic acids having a crosslinked or branched structure may be used in combination. Examples of trivalent or higher carboxylic acids include trimellitic acid, pyromellitic acid, their anhydrides, or their lower (e.g., C1-5) alkyl esters.

[0074] The polyvalent carboxylic acid may be used alone or in combination of two or more.

[0075] Examples of the polyol include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, and neopentyl glycol), alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, and hydrogenated bisphenol A), and aromatic diols (e.g., ethylene oxide adducts of bisphenol A and propylene oxide adducts of bisphenol A). Among these, aromatic diols and alicyclic diols are preferred, and aromatic diols are more preferred.

[0076] As the polyol, a diol may be used in combination with a trivalent or higher polyol having a cross-linked structure or a branched structure. Examples of the trivalent or higher polyol include glycerin, trimethylolpropane, and pentaerythritol.

[0077] The polyols may be used alone or in combination of two or more.

[0078] The glass transition temperature (Tg) of the amorphous polyester resin is preferably 50°C or higher and 80°C or lower, and more preferably 50°C or higher and 65°C or lower.

[0079] The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), more specifically, by the "extrapolated glass transition onset temperature" method described in the glass transition temperature determination method of JIS K7121:1987 "Plastics - Determination of Transition Temperatures".

[0080] The weight average molecular weight (Mw) of the amorphous polyester resin is preferably 5,000 to 1,000,000, and more preferably 7,000 to 500,000.

[0081] The number average molecular weight (Mn) of the amorphous polyester resin is preferably 2,000 or more and 100,000 or less.

[0082] The molecular weight distribution Mw / Mn of the amorphous polyester resin is preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less.

[0083] The weight-average molecular weight and number-average molecular weight were measured by gel permeation chromatography (GPC). Molecular weight measurements using GPC were performed using a Tosoh GPC HLC-8120GPC, a Tosoh TSKgel SuperHM-M (15 cm) column, and THF as a solvent. The weight-average molecular weight and number-average molecular weight were calculated from the measurement results using a molecular weight calibration curve prepared using monodisperse polystyrene standard samples.

[0084] The amorphous polyester resin is obtained by a known production method. Specifically, for example, the polymerization temperature is set at 180° C. to 230° C., and the pressure in the reaction system is reduced as needed to allow the reaction to proceed while removing water or alcohol generated during condensation.

[0085] If the raw monomers are insoluble or incompatible at the reaction temperature, a high-boiling-point solvent can be added as a dissolution aid to dissolve them. In this case, the polycondensation reaction is carried out while distilling off the dissolution aid. If a monomer with poor compatibility is present during the copolymerization reaction, the monomer with poor compatibility can be pre-condensed with the acid or alcohol to be polycondensed with the monomer, and then polycondensed with the main component.

[0086] Crystalline polyester resin

[0087] Examples of the crystalline polyester resin include polycondensates of polycarboxylic acids and polyols. As the crystalline polyester resin, a commercially available product may be used, or a synthetic product may be used.

[0088] Here, in order to facilitate the formation of a crystal structure of the crystalline polyester resin, the crystalline polyester resin is preferably a polycondensate obtained using a linear aliphatic polymerizable monomer rather than a polycondensate obtained using a polymerizable monomer having an aromatic ring.

[0089] Examples of the polycarboxylic acid include aliphatic dicarboxylic acids (e.g., oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, and naphthalene-2,6-dicarboxylic acid), anhydrides thereof, or lower (e.g., carbon number 1 to 5) alkyl esters thereof.

[0090] Among the polycarboxylic acids, dicarboxylic acids may be used in combination with tricarboxylic acids or higher valence carboxylic acids that have a cross-linked structure or a branched structure. Examples of tricarboxylic acids include aromatic carboxylic acids (e.g., 1,2,3-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, etc.), their anhydrides, or their lower (e.g., C1-5) alkyl esters.

[0091] As the polycarboxylic acid, these dicarboxylic acids can be used in combination with a dicarboxylic acid having a sulfonic acid group or a dicarboxylic acid having an ethylenic double bond.

[0092] The polyvalent carboxylic acid may be used alone or in combination of two or more.

[0093] Examples of the polyol include aliphatic diols (e.g., linear aliphatic diols having a main chain portion with 7 to 20 carbon atoms). Examples of the aliphatic diol include ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,14-eicosanediol. Among these, preferred aliphatic diols are 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol.

[0094] Among the polyols, diols may be used in combination with trivalent or higher alcohols having a cross-linked structure or a branched structure. Examples of the trivalent or higher alcohols include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.

[0095] The polyols may be used alone or in combination of two or more.

[0096] Here, the content of the aliphatic diol in the polyol is preferably 80 mol% or more, and preferably 90 mol% or more.

[0097] The melting temperature of the crystalline polyester resin is preferably 50°C to 100°C, more preferably 55°C to 90°C, and even more preferably 60°C to 85°C.

[0098] The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) according to the “melting peak temperature” described in the method for measuring melting temperature in JIS K7121:1987 “Determination of transition temperatures of plastics”.

[0099] The weight average molecular weight (Mw) of the crystalline polyester resin is preferably 6,000 or more and 35,000 or less.

[0100] The crystalline polyester resin can be obtained, for example, by a known production method similar to the amorphous polyester.

[0101] The content of the binding resin is preferably 40% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 90% by mass or less, and even more preferably 60% by mass or more and 85% by mass or less, based on the entire toner particles.

[0102] -Colorant-

[0103] Examples of the colorant include carbon black, chrome yellow, Hansa yellow, benzidine yellow, vat yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, sulfur-resistant orange, Vochug red, permanent red, brilliant carmine 3B, brilliant carmine 6B, DuPont Oil Red, pyrazolone red, litho red, rhodamine B lake, red lake C, pigment red, rose red, aniline blue, ultramarine blue, oil-soluble blue, methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, malachite green oxalate and other pigments; and dyes such as acridine-based, xanthene-based, azo-based, benzoquinone-based, azine-based, anthraquinone-based, thioindigo-based, dioxazine-based, thiazine-based, azomethine-based, indigo-based, phthalocyanine-based, nigrosine-based, polymethine-based, triphenylmethane-based, diphenylmethane-based, and thiazole-based dyes.

[0104] The coloring agent may be used alone or in combination of two or more.

[0105] The colorant may be a colorant that has been subjected to surface treatment as needed, or may be used in combination with a dispersant. Furthermore, two or more colorants may be used in combination.

[0106] The content of the colorant is preferably from 1% by mass to 30% by mass, and more preferably from 3% by mass to 15% by mass, based on the total mass of the toner particles.

[0107] -Release agent-

[0108] Examples of release agents include hydrocarbon waxes, natural waxes such as carnauba wax, rice wax, and candelilla wax, synthetic or mineral / petroleum waxes such as montan wax, and ester waxes such as fatty acid esters and montanic acid esters, but the release agent is not limited thereto.

[0109] The melting temperature of the release agent is preferably 50°C to 110°C, more preferably 60°C to 100°C.

[0110] The melting temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC) according to the “melting peak temperature” described in the method for measuring melting temperature in JIS K7121:1987 “Determination of transition temperatures of plastics”.

[0111] The content of the release agent is preferably from 1% by mass to 20% by mass, and more preferably from 5% by mass to 15% by mass, based on the total mass of the toner particles.

[0112] -Other additives-

[0113] Examples of other additives include known additives such as magnetic materials, charge control agents, and inorganic powders. These additives may be contained in the toner particles as internal additives.

[0114] - Characteristics of toner particles, etc. -

[0115] The toner particles may be toner particles of a single-layer structure or toner particles of a so-called core / shell structure composed of a core (core particle) and a coating layer (shell layer) that covers the core.

[0116] The toner particles of a core / shell structure may be composed of, for example, a core portion comprising a binder resin and, if necessary, other additives such as a colorant and a release agent, and a coating layer comprising the binder resin.

[0117] The volume average particle diameter (D50v) of the toner particles is preferably 2 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less.

[0118] The volume average particle diameter (D50v) of the toner particles is measured using Coulter Multisizer II (manufactured by Beckman Coulter) and an electrolyte using ISOTON-II (manufactured by Beckman Coulter).

[0119] During measurement, 0.5 mg to 50 mg of the measurement sample is added to 2 ml of a 5% by mass aqueous solution of a surfactant (preferably sodium alkylbenzenesulfonate) as a dispersant, and then added to 100 ml to 150 ml of the electrolyte.

[0120] The electrolyte solution containing the sample was dispersed using an ultrasonic disperser for 1 minute. The particle size distribution of particles ranging from 2 μm to 60 μm was measured using a Coulter Multisizer II with a 100 μm aperture. A total of 50,000 particles were sampled. The volume-based particle size distribution was plotted starting from the smaller diameter, and the cumulative 50% particle size was defined as the volume average particle size (D50v).

[0121] The average circularity of the toner particles is preferably from 0.94 to 1.00, and more preferably from 0.95 to 0.98.

[0122] The average circularity of the toner particles is determined by (equivalent circular circumference) / (circumference) [(circumference of a circle having the same projected area as the particle image) / (circumference of the particle projected image)]. Specifically, it is a value measured by the following method.

[0123] First, the toner particles to be measured were collected by suction and formed into a flat stream. This stream was then momentarily flashed to obtain a still image of the particles. This image was then analyzed using a flow particle image analyzer (FPIA-3000, manufactured by Sysmex) to determine the average circularity. The number of samples used to determine the average circularity was 3,500.

[0124] When the toner has an external additive, the toner (developer) to be measured is dispersed in water containing a surfactant and then subjected to ultrasonic treatment to obtain toner particles from which the external additive is removed.

[0125] [Layered compound particles]

[0126] The layered compound particles are particles of a compound having a layered structure. Examples of the layered compound particles include melamine cyanurate particles, boron nitride particles, graphite fluoride particles, molybdenum disulfide particles, and mica particles.

[0127] From the perspective of suppressing the aggregation of the layered structure compound particles, the volume average particle size of the layered structure compound particles is preferably 0.1 μm to 5.0 μm, more preferably 0.1 μm to 4.0 μm, and even more preferably 0.1 μm to 3.0 μm. The volume average particle size of the layered structure compound particles can be controlled by pulverization, classification, or a combination of pulverization and classification.

[0128] The volume average particle size of the layered structure compound is determined by the following measurement method.

[0129] First, the layered compound particles are separated from the toner. The method for separating the layered compound particles from the toner is not limited. For example, the toner is dispersed in water containing a surfactant, ultrasonic waves are applied to the resulting dispersion, and the dispersion is then centrifuged at high speed to separate the toner particles, layered compound particles, and inorganic particles based on their specific gravity. The fraction containing the layered compound particles is extracted and dried to obtain the layered compound particles.

[0130] Next, the layered structure compound particles are added to an aqueous electrolyte solution (isotonic aqueous solution) and dispersed by applying ultrasonic waves for 30 seconds or longer. This dispersion is used as a sample, and the particle size is measured using a laser diffraction scattering particle size distribution analyzer (e.g., Microtrac MT3000II manufactured by Microtrac BEL). The volume-based particle size distribution is calculated as the volume average particle size, with the particle size at the cumulative 50% point from the smaller diameter side being the volume average particle size.

[0131] To achieve the lubricating effect of the layered structure compound particles, the content of the layered structure compound particles is preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and even more preferably 0.05% by mass or more, relative to the total toner. To suppress aggregation of the layered structure compound particles, the content of the layered structure compound particles is preferably 2.0% by mass or less, more preferably 1.0% by mass or less, and even more preferably 0.8% by mass or less, relative to the total toner.

[0132] [Inorganic particles]

[0133] Examples of inorganic particles include SiO2, TiO2, Al2O3, CuO, ZnO, SnO2, CeO2, Fe2O3, MgO, BaO, CaO, K2O, Na2O, ZrO2, CaO·SiO2, K2O·(TiO2) n , Al2O3·2SiO2, CaCO3, MgCO3, BaSO4, MgSO4, etc.

[0134] The surface of the inorganic particles is suitably subjected to hydrophobization treatment. Hydrophobization treatment is carried out by, for example, immersing the inorganic particles in a hydrophobization treatment agent. There is no particular limitation on the hydrophobization treatment agent, and for example, silane coupling agents, silicone oils, titanate coupling agents, aluminum coupling agents, etc. can be cited. These treatment agents can be used alone or in combination with two or more. About the amount of the hydrophobization treatment agent, for example, relative to 100 mass parts of inorganic particles, it is generally less than 10 mass parts by more than 1 mass part.

[0135] From the perspective of suppressing offset when fixing a toner image to a recording medium, the number average particle size of the inorganic particles as a whole is preferably from 0.010 μm to 0.400 μm, more preferably from 0.012 μm to 0.380 μm, and even more preferably from 0.015 μm to 0.350 μm. The number average particle size is the particle size at the cumulative 50% point from the smallest diameter side in a number-based particle size distribution.

[0136] From the perspective of suppressing offset when fixing a toner image to a recording medium, the average circularity of the inorganic particles as a whole is preferably 0.6 or greater, more preferably 0.7 or greater, and even more preferably 0.8 or greater. The average circularity is the cumulative circularity of 50% of the points with the smallest circularity in a number-based circularity distribution.

[0137] From the perspective of suppressing staining when the toner image is fixed to the recording medium, the proportion of irregular inorganic particles (preferably irregular silica particles) having a roundness of 0.5 to 0.9 and a particle size of 0.015 μm to 0.350 μm relative to the total inorganic particles is 2% to 70%, preferably 10% to 65%, and more preferably 20% to 65%.

[0138] The average circularity of the irregular inorganic particles (preferably irregular silica particles) having a roundness of 0.5 to 0.9 and a particle size of 0.015 μm to 0.350 μm is preferably 0.5 to 0.9, more preferably 0.7 to 0.9, and the number average particle size is preferably 0.015 μm to 0.350 μm, more preferably 0.020 μm to 0.200 μm.

[0139] The circularity and particle size of the inorganic particles and the number ratio of irregular-shaped inorganic particles were measured as follows.

[0140] First, the inorganic particles are separated from the toner. The method for separating the inorganic particles from the toner is not limited. For example, the toner is dispersed in water containing a surfactant, ultrasonic waves are applied to the resulting dispersion, and then the dispersion is centrifuged at high speed to separate the toner particles, layered compound particles, and inorganic particles based on their specific gravity. The fraction containing the inorganic particles is extracted and dried to obtain the inorganic particles.

[0141] Next, the inorganic particles were imaged using a scanning electron microscope (SEM), and the circularity of each of 1000 randomly selected primary particles was determined by image analysis (=4π×(area of particle image)÷(circumference of particle image) 2 ) and equivalent circle diameter (μm). The equivalent circle diameter is the particle size.

[0142] The ratio of irregular-shaped inorganic particles to all inorganic particles was calculated based on the number of particles having a roundness of 0.5 to 0.9 and a particle size of 0.015 μm to 0.350 μm among 1000 primary particles.

[0143] As inorganic particles and irregularly shaped inorganic particles, silica particles are preferred because they can easily control their roundness. For example, fumed silica particles can be mixed with sol-gel silica particles to adjust the ratio of irregularly shaped silica particles (silica particles having a roundness of 0.5 to 0.9 and a particle size of 0.015 μm to 0.350 μm) relative to the total number of silica particles.

[0144] Methods for producing fumed silica particles are well known. The sol-gel method for producing sol-gel silica particles is also well known. For example, the sol-gel method involves mixing tetraalkoxysilane, water, and alcohol, and adding aqueous ammonia to the resulting mixture to prepare a silica sol suspension; centrifuging the wet silica gel from the silica sol suspension; and drying the wet silica gel to obtain silica particles. Examples of tetraalkoxysilanes include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, and tetrabutoxysilane.

[0145] From the perspective of suppressing contamination when fixing the toner image to the recording medium, the content of the entire inorganic particles is preferably 0.3 mass % to 20 mass % relative to the entire toner, more preferably 1.0 mass % to 15 mass %, and even more preferably 2.0 mass % to 10 mass %.

[0146] From the perspective of suppressing staining when the toner image is fixed to the recording medium, the mass ratio of irregular inorganic particles (preferably irregular silica particles) having a roundness of 0.5 to 0.9 and a particle size of 0.015 μm to 0.350 μm relative to the total inorganic particles is preferably 3.0 mass % to 82 mass %, more preferably 17 mass % to 78 mass %, and even more preferably 32 mass % to 78 mass %.

[0147] From the perspective of suppressing contamination when the toner image is fixed to the recording medium, the mass basis ratio Ma / Mb of the content Ma of the layered structure compound particles contained in the toner of this embodiment to the content Mb of the irregular inorganic particles (preferably irregular silica particles) is preferably not less than 0.004 and not more than 1.0, more preferably not less than 0.01 and not more than 0.8, and further preferably not less than 0.05 and not more than 0.6.

[0148] [Other additives]

[0149] The toner of this embodiment may contain external additives other than the layered structure compound particles and the inorganic particles. Examples of such external additives include resin particles (polystyrene, polymethyl methacrylate, melamine resin, and the like), detergent active agents (such as metal salts of higher fatty acids, such as zinc stearate, and particles of fluorine-based high molecular weight substances), and the like.

[0150] When the toner of this embodiment contains external additives other than the layered structure compound particles and the inorganic particles, the total amount of the external additives added is preferably 0.01% by mass to 5.0% by mass, more preferably 0.01% by mass to 2.0% by mass, relative to the toner particles.

[0151] [Toner Manufacturing Method]

[0152] The toner according to this embodiment is obtained by adding an external additive to the toner particles after producing the toner particles.

[0153] Toner particles can be produced by any of dry methods (e.g., kneading and pulverization methods) or wet methods (e.g., aggregation and coalescence methods (aggregation-coagulation methods), suspension polymerization methods, and dissolution-suspension methods). These methods are not particularly limited, and known methods can be employed. Among these, toner particles are preferably produced by aggregation and coalescence methods.

[0154] Specifically, for example, in the case of producing toner particles by an agglomeration and merging method, the toner particles are produced through the following steps: a step of preparing a resin particle dispersion in which resin particles serving as a binding resin are dispersed (resin particle dispersion preparation step); a step of agglomerating resin particles (and other particles if necessary) in the resin particle dispersion (in a dispersion after mixing other particle dispersions if necessary) to form agglomerated particles (agglomerated particle formation step); and a step of heating the agglomerated particle dispersion in which the agglomerated particles are dispersed to fuse / merge (fusion and unification) the agglomerated particles to form toner particles (fusion / merging step).

[0155] The details of each step are described below.

[0156] In the following description, a method for obtaining toner particles containing a colorant and a release agent is described, but the colorant and the release agent are additives used as needed. Of course, other additives besides the colorant and the release agent may also be used.

[0157] - Resin particle dispersion preparation step -

[0158] A resin particle dispersion in which resin particles serving as a binder resin are dispersed is prepared, and at the same time, for example, a colorant particle dispersion in which colorant particles are dispersed and a release agent particle dispersion in which release agent particles are dispersed are prepared.

[0159] The resin particle dispersion is prepared by, for example, dispersing the resin particles in a dispersion medium using a surfactant.

[0160] Examples of the dispersion medium used in the resin particle dispersion include aqueous media.

[0161] Examples of the aqueous medium include water such as distilled water and ion-exchanged water, and alcohols. These media may be used alone or in combination of two or more.

[0162] Examples of surfactants include anionic surfactants such as sulfate esters, sulfonates, phosphates, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycols, alkylphenol ethylene oxide adducts, and polyols. Among these, anionic surfactants and cationic surfactants are particularly useful. Nonionic surfactants may also be used in combination with anionic or cationic surfactants.

[0163] The surfactant may be used alone or in combination of two or more.

[0164] In the resin particle dispersion, as a method for dispersing the resin particles in the dispersion medium, for example, common dispersion methods using a rotary shearing homogenizer or a ball mill, sand mill, bead mill, etc. with a medium can be cited. In addition, depending on the type of resin particles, the resin particles can also be dispersed in the dispersion medium using a phase inversion emulsification method. The phase inversion emulsification method is a method in which the resin to be dispersed is dissolved in a hydrophobic organic solvent that can dissolve the resin, a base is added to the organic continuous phase (O phase) for neutralization, and then an aqueous medium (W phase) is added to thereby invert the phase from W / O to O / W, so that the resin is dispersed in the aqueous medium in the form of particles.

[0165] The volume average particle size of the resin particles dispersed in the resin particle dispersion is, for example, preferably 0.01 μm or more and 1 μm or less, more preferably 0.08 μm or more and 0.8 μm or less, and even more preferably 0.1 μm or more and 0.6 μm or less.

[0166] The volume average particle size of the resin particles is determined using a particle size distribution obtained by measurement using a laser diffraction particle size analyzer (e.g., LA-700 manufactured by Horiba, Ltd.). For each of the divided particle size ranges (bins), a cumulative distribution is plotted starting from the smaller particle size side. The particle size at the 50% cumulative point relative to all particles is measured and designated as the volume average particle size D50v. The volume average particle size of particles in other dispersions is similarly measured.

[0167] The content of the resin particles contained in the resin particle dispersion is preferably from 5% by mass to 50% by mass, and more preferably from 10% by mass to 40% by mass.

[0168] For example, a colorant particle dispersion and a release agent particle dispersion are prepared in the same manner as the resin particle dispersion. Specifically, the volume average particle size, dispersion medium, dispersion method, and particle content of the particles in the resin particle dispersion are the same for the colorant particles dispersed in the colorant particle dispersion and the release agent particles dispersed in the release agent particle dispersion.

[0169] - Agglomerated Particle Formation Step-

[0170] Next, the resin particle dispersion, the colorant particle dispersion, and the release agent particle dispersion are mixed.

[0171] Thereafter, the resin particles, the colorant particles, and the release agent particles are heterogeneously aggregated in the mixed dispersion to form aggregated particles containing the resin particles, the colorant particles, and the release agent particles and having a diameter close to that of the target toner particles.

[0172] Specifically, for example, a coagulant is added to the mixed dispersion, and the pH of the mixed dispersion is adjusted to acidic (for example, pH 2 or higher and pH 5 or lower), and a dispersion stabilizer is added as needed. Thereafter, the mixture is heated to a temperature close to the glass transition temperature of the resin particles (specifically, for example, the glass transition temperature of the resin particles is -30°C to the glass transition temperature is -10°C), so that the particles dispersed in the mixed dispersion are agglomerated to form agglomerated particles.

[0173] In the aggregated particle formation step, for example, a coagulant can be added to the mixed dispersion at room temperature (e.g., 25° C.) while stirring the mixed dispersion using a rotary shearing homogenizer, the pH of the mixed dispersion can be adjusted to acidic (e.g., pH 2 to 5), and a dispersion stabilizer can be added as needed, followed by heating.

[0174] Examples of the coagulant include surfactants with opposite polarity to the surfactant contained in the mixed dispersion, inorganic metal salts, and divalent or higher metal complexes. When a metal complex is used as the coagulant, the amount of surfactant used is reduced, and charging characteristics are improved.

[0175] If necessary, an additive that forms a complex or similar bond with the metal ion of the coagulant can be used together with the coagulant. As such an additive, a chelating agent is preferably used.

[0176] Examples of the inorganic metal salt include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate; and inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide.

[0177] As the chelating agent, a water-soluble chelating agent can be used. Examples of the chelating agent include hydroxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid; aminocarboxylic acids such as iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA); and the like.

[0178] The amount of the chelating agent added is preferably 0.01 parts by mass or more and 5.0 parts by mass or less, and more preferably 0.1 parts by mass or more and less than 3.0 parts by mass, relative to 100 parts by mass of the resin particles.

[0179] - Fusion / Merging Steps-

[0180] Next, the aggregated particle dispersion containing the dispersed aggregated particles is heated to, for example, a temperature equal to or higher than the glass transition temperature of the resin particles (eg, 10° C. to 30° C. higher than the glass transition temperature of the resin particles) to fuse / combine the aggregated particles to form toner particles.

[0181] Through the above steps, toner particles are obtained.

[0182] After obtaining a dispersion of aggregated particles in which aggregated particles are dispersed, colorant particles can be manufactured by the following steps: further mixing the aggregated particle dispersion with a resin particle dispersion in which resin particles are dispersed, and agglomerating the resin particles so as to further adhere to the surface of the aggregated particles to form second aggregated particles; and heating the second aggregated particle dispersion in which the second aggregated particles are dispersed to fuse / merge the second aggregated particles to form colorant particles with a core / shell structure.

[0183] After the fusion / merging step, the toner particles formed in the solution are subjected to known washing, solid-liquid separation, and drying steps to obtain dry toner particles. For the washing step, displacement washing with ion-exchanged water is suitable for charging performance. For the solid-liquid separation step, suction filtration, pressure filtration, etc. are suitable for productivity. For the drying step, freeze drying, airflow drying, fluidized bed drying, vibrating fluidized bed drying, etc. are suitable for productivity.

[0184] The toner of this embodiment is then produced by, for example, adding an external additive to the resulting dried toner particles and mixing them. Mixing can be performed using, for example, a V-blender, Henschel mixer, or Loedige mixer. Furthermore, if necessary, coarse toner particles can be removed using a vibrating screen or pneumatic screen.

[0185] <Electrostatic Image Developer>

[0186] The electrostatic image developer according to the present embodiment includes at least the toner according to the present embodiment.

[0187] The electrostatic image developer of the present embodiment may be a one-component developer containing only the toner of the present embodiment, or a two-component developer in which the toner is mixed with a carrier.

[0188] The carrier is not particularly limited, and known carriers may be used. Examples include coated carriers in which a core material composed of magnetic powder is coated with a resin; magnetic powder-dispersed carriers in which magnetic powder is dispersed and mixed in a matrix resin; and resin-impregnated carriers in which porous magnetic powder is impregnated with a resin. Magnetic powder-dispersed carriers and resin-impregnated carriers may also be carriers in which the constituent particles of the carrier serve as a core material and are coated with a resin.

[0189] Examples of the magnetic powder include magnetic metals such as iron, nickel, and cobalt; and magnetic oxides such as ferrite and magnetite.

[0190] Examples of coating resins and base resins include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymers, styrene-acrylate copolymers, pure silicone resins containing organosiloxane bonds or modified forms thereof, fluororesins, polyesters, polycarbonates, phenolic resins, and epoxy resins. The coating resin and base resin may contain other additives such as conductive particles. Examples of conductive particles include particles of metals such as gold, silver, and copper, carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

[0191] When utilizing the surface of the resin coating core material, can cite the method etc. of coating with the coating layer formation solution that utilizes coating resin and various additives (used as needed) dissolved in appropriate solvent.As solvent, there is no particular limitation, consider the kind of resin used, coating suitability etc. and select and get final product.

[0192] Specific resin coating methods include: an immersion method, in which the core material is immersed in a coating layer forming solution; a spray method, in which the coating layer forming solution is sprayed onto the surface of the core material; a fluidized bed method, in which the coating layer forming solution is sprayed while the core material is suspended by flowing air; a kneading coater method, in which the core material of the carrier is mixed with the coating layer forming solution in a kneading coater and the solvent is then removed; and the like.

[0193] The mixing ratio (mass ratio) of the toner and the carrier in the two-component developer is preferably toner:carrier=1:100 to 30:100, more preferably 3:100 to 20:100.

[0194] <Image Forming Apparatus, Image Forming Method>

[0195] The image forming apparatus of this embodiment includes: an image holder; a charging mechanism for charging the surface of the image holder; an electrostatic image forming mechanism for forming an electrostatic image on the charged surface of the image holder; a developing mechanism for storing an electrostatic image developer and developing the electrostatic image formed on the surface of the image holder into a toner image using the electrostatic image developer; a transfer mechanism for transferring the toner image formed on the surface of the image holder to the surface of a recording medium; and a fixing mechanism for fixing the toner image transferred to the surface of the recording medium. The electrostatic image developer of this embodiment is used as the electrostatic image developer.

[0196] An image forming method (image forming method of this embodiment) having the following steps is implemented using the image forming device of this embodiment: a charging step of charging the surface of the image retainer; an electrostatic image forming step of forming an electrostatic image on the charged surface of the image retainer; a developing step of developing the electrostatic image formed on the surface of the image retainer into a toner image using the electrostatic image developer of this embodiment; a transferring step of transferring the toner image formed on the surface of the image retainer to the surface of the recording medium; and a fixing step of fixing the toner image transferred to the surface of the recording medium.

[0197] The image forming device of this embodiment can be applied to the following well-known image forming devices: a device using a direct transfer method for directly transferring a toner image formed on the surface of an image holder to a recording medium; a device using an intermediate transfer method for transferring a toner image formed on the surface of an image holder to the surface of an intermediate transfer member for the first time, and transferring the toner image transferred to the surface of the intermediate transfer member to the surface of a recording medium for a second time; a device having a cleaning mechanism for cleaning the surface of an image holder after the transfer of the toner image and before charging; a device having a static elimination mechanism for irradiating the surface of an image holder with static elimination light for static elimination after the transfer of the toner image and before charging; and the like.

[0198] When the image forming device of this embodiment is an intermediate transfer type device, the transfer mechanism used is, for example, a structure having the following components: an intermediate transfer body that transfers the colorant image to the surface; a primary transfer mechanism that transfers the colorant image formed on the surface of the image retaining body to the surface of the intermediate transfer body for the first time; and a secondary transfer mechanism that transfers the colorant image transferred to the surface of the intermediate transfer body to the surface of the recording medium for the second time.

[0199] In the image forming apparatus of this embodiment, for example, the portion including the developing mechanism may be a cartridge structure (process cartridge) that is detachable from the image forming apparatus. For example, a process cartridge that stores the electrostatic image developer of this embodiment and includes a developing mechanism is suitable.

[0200] An example of the image forming apparatus according to the present embodiment is shown below, but the present invention is not limited thereto. In the following description, the main parts shown in the drawings are described, and the other parts are omitted.

[0201] Figure 1 2 is a diagram schematically showing the configuration of the image forming apparatus according to this embodiment.

[0202] Figure 1 The image forming apparatus shown includes first to fourth electrophotographic image forming units 10Y, 10M, 10C, and 10K (image forming mechanisms) that output images of yellow (Y), magenta (M), cyan (C), and black (K) based on color-separated image data. These image forming units (hereinafter sometimes referred to as "units") 10Y, 10M, 10C, and 10K are arranged in parallel horizontally at a predetermined distance from one another. These units 10Y, 10M, 10C, and 10K may be process cartridges that are attachable to and detachable from the image forming apparatus.

[0203] An intermediate transfer belt (an example of an intermediate transfer member) 20 extends above each unit 10Y, 10M, 10C, and 10K, passing through each unit. The intermediate transfer belt 20 is wound around a drive roller 22 and a support roller 24, running from the first unit 10Y toward the fourth unit 10K. The support roller 24 is biased away from the drive roller 22 by a spring (not shown), thereby applying tension to the intermediate transfer belt 20 wound between the two units. An intermediate transfer member cleaning device 30 is provided on the image holder side of the intermediate transfer belt 20, facing the drive roller 22.

[0204] Yellow, magenta, cyan and black toners stored in toner cartridges 8Y, 8M, 8C and 8K are supplied to developing devices (an example of developing mechanisms) 4Y, 4M, 4C and 4K of the respective units 10Y, 10M, 10C and 10K.

[0205] The first to fourth units 10Y, 10M, 10C, and 10K have the same configuration and operation, and therefore the first unit 10Y disposed upstream in the running direction of the intermediate transfer belt and forming a yellow image will be described as a representative.

[0206] The first unit 10Y includes a photoreceptor 1Y, which functions as an image holder. Sequentially arranged around the photoreceptor 1Y are: a charging roller (an example of a charging mechanism) 2Y, which charges the surface of the photoreceptor 1Y to a predetermined potential; an exposure device (an example of an electrostatic image forming mechanism) 3, which exposes the charged surface using laser light 3Y based on a color separation image signal to form an electrostatic image; a developing device (an example of a developing mechanism) 4Y, which supplies the charged toner to the electrostatic image to develop it; a primary transfer roller 5Y (an example of a primary transfer mechanism), which transfers the developed toner image to the intermediate transfer belt 20; and a photoreceptor cleaning device (an example of a cleaning mechanism) 6Y, which removes toner remaining on the surface of the photoreceptor 1Y after the primary transfer.

[0207] The primary transfer roller 5Y is disposed inside the intermediate transfer belt 20, positioned opposite the photoreceptor 1Y. Each of the primary transfer rollers 5Y, 5M, 5C, and 5K in each unit is connected to a bias power supply (not shown) for applying a primary transfer bias. Each bias power supply is controlled by a control unit (not shown) to change the value of the transfer bias applied to each primary transfer roller.

[0208] Next, the operation of forming a yellow image in the first unit 10Y will be described.

[0209] First, before operation, the surface of the photoreceptor 1Y is charged to a potential of -600V to -800V by the charging roller 2Y.

[0210] The photoreceptor 1Y has a conductivity (e.g., a volume resistivity of 1×10 -6 The photosensitive layer is formed by laminating a photosensitive layer on a substrate (with a resistance of Ωcm or less). This photosensitive layer normally has a high electrical resistance (commonly seen in resins), but when irradiated with laser light, the resistivity of the portion exposed to the laser light changes. Therefore, based on yellow image data sent from a control unit (not shown), laser light 3Y is irradiated from exposure device 3 onto the charged surface of photoreceptor 1Y. This forms an electrostatic image of a yellow image pattern on the surface of photoreceptor 1Y.

[0211] The electrostatic image is an image formed on the surface of the photoreceptor 1Y by charging, which is a so-called negative latent image. The negative latent image is formed as follows: the resistivity of the irradiated portion of the photosensitive layer is reduced by using the laser beam 3Y, so that the charged charge on the surface of the photoreceptor 1Y flows; on the other hand, the charge of the portion not irradiated by the laser beam 3Y remains, thereby forming the negative latent image.

[0212] The electrostatic image formed on the photoreceptor 1Y rotates to a predetermined development position as the photoreceptor 1Y moves. At the development position, the electrostatic image on the photoreceptor 1Y is developed into a toner image by the developing device 4Y and visualized.

[0213] The developing device 4Y stores an electrostatic image developer, for example, containing at least yellow toner and a carrier. The yellow toner is triboelectrically charged by agitation within the developing device 4Y, acquiring a charge of the same polarity (negative) as the charge on the photoreceptor 1Y and being retained on the developer roller (an example of a developer retainer). The surface of the photoreceptor 1Y then passes through the developing device 4Y, where the yellow toner electrostatically adheres to the de-electrified latent image on the surface of the photoreceptor 1Y, developing the latent image with the yellow toner. The photoreceptor 1Y, bearing the yellow toner image, continues to operate at a predetermined speed, transferring the developed toner image on the photoreceptor 1Y to a predetermined primary transfer position.

[0214] When the yellow toner image on the photoreceptor 1Y is transported to the primary transfer position, a primary transfer bias is applied to the primary transfer roller 5Y. The electrostatic force from the photoreceptor 1Y toward the primary transfer roller 5Y acts on the toner image, transferring the toner image on the photoreceptor 1Y to the intermediate transfer belt 20. The transfer bias applied at this time has a polarity (+) opposite to the polarity (-) of the toner and is controlled by a control unit (not shown) in the first unit 10Y to, for example, +10 μA.

[0215] On the other hand, the toner remaining on the photoreceptor 1Y is removed and recovered by the photoreceptor cleaning device 6Y.

[0216] The primary transfer bias applied to the primary transfer rollers 5M, 5C, and 5K in and after the second unit 10M is also controlled in accordance with the first unit.

[0217] In this manner, the intermediate transfer belt 20 to which the yellow toner image has been transferred by the first unit 10Y is sequentially conveyed through the second to fourth units 10M, 10C, and 10K, and the toner images of the respective colors are multiply transferred in a superimposed manner.

[0218] After passing through the first through fourth units and having the four-color toner images multiply transferred onto the intermediate transfer belt 20, it reaches the secondary transfer section. This section consists of the intermediate transfer belt 20, a backup roller 24 in contact with the inner surface of the intermediate transfer belt, and a secondary transfer roller (an example of a secondary transfer mechanism) 26 positioned on the image-holding side of the intermediate transfer belt 20. Meanwhile, recording paper (an example of recording medium) P is fed by a feeding mechanism at a predetermined timing to the gap between the secondary transfer roller 26 and the intermediate transfer belt 20, and a secondary transfer bias is applied to the backup roller 24. The applied transfer bias has the same (-) polarity as the toner (-). Electrostatic force from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, transferring the toner image from the intermediate transfer belt 20 to the recording paper P. The secondary transfer bias is determined based on the resistance detected by a resistance detection mechanism (not shown) that detects the resistance of the secondary transfer section, and the voltage is controlled accordingly.

[0219] Thereafter, the recording paper P is fed into a pressure-contact portion (nip portion) of a pair of fixing rollers in a fixing device (an example of a fixing mechanism) 28 , whereby the toner image is fixed to the recording paper P to form a fixed image.

[0220] Examples of the recording paper P to which the toner image is transferred include plain paper used in electrophotographic copy machines, printers, etc. Examples of the recording medium include, in addition to the recording paper P, OHP transparent films and the like.

[0221] To further improve the smoothness of the image surface after fixing, the surface of the recording paper P is preferably smooth. For example, coated paper obtained by coating the surface of plain paper with resin or the like, or art paper for printing, is suitable.

[0222] The recording paper P on which the color image has been fixed is fed to the discharge portion, completing a series of color image forming operations.

[0223] <Process Cartridge, Toner Cartridge>

[0224] The process cartridge of this embodiment is a process cartridge that is detachably mounted in an image forming apparatus and includes a developing mechanism that stores the electrostatic image developer of this embodiment and develops an electrostatic image formed on a surface of an image holding member into a toner image using the electrostatic image developer.

[0225] The process cartridge of this embodiment is not limited to the above-described configuration, and may include a developing mechanism and, if necessary, at least one other mechanism selected from an image holding member, a charging mechanism, an electrostatic image forming mechanism, and a transfer mechanism.

[0226] An example of the process cartridge according to the present embodiment is shown below, but the present invention is not limited thereto. In the following description, the main parts shown in the drawings are described, and the other descriptions are omitted.

[0227] Figure 2 It is a schematic structural diagram showing the process cartridge of this embodiment.

[0228] Figure 2 The processing box 200 shown is constructed by, for example, integrally combining and retaining a photosensitive body 107 (an example of an image holding body) and a charging roller 108 (an example of a charging mechanism) provided around the photosensitive body 107, a developing device 111 (an example of a developing mechanism), and a photosensitive body cleaning device 113 (an example of a cleaning mechanism) through a shell 117 having a mounting guide 116 and an opening 118 for exposure to form an ink cartridge.

[0229] Figure 2 In the figure, 109 denotes an exposure device (an example of an electrostatic image forming mechanism), 112 denotes a transfer device (an example of a transfer mechanism), 115 denotes a fixing device (an example of a fixing mechanism), and 300 denotes recording paper (an example of a recording medium).

[0230] The toner cartridge of the present embodiment stores the toner of the present embodiment and is detachably mounted in an image forming apparatus. The toner cartridge stores replenishment toner to be supplied to a developing mechanism provided in the image forming apparatus.

[0231] Figure 1 The image forming apparatus shown is an image forming apparatus having a detachable configuration of toner cartridges 8Y, 8M, 8C, and 8K. The developing devices 4Y, 4M, 4C, and 4K are connected to the toner cartridges corresponding to the respective developing devices (colors) via toner supply tubes (not shown). When the toner stored in a toner cartridge becomes insufficient, the toner cartridge is replaced.

[0232] [Example]

[0233] The following examples illustrate the embodiments of the present invention in detail, but the embodiments of the present invention are not limited to these examples. In the following description, "parts" and "%" are based on mass unless otherwise specified.

[0234] <Production of Toner Particles>

[0235] [Preparation of Amorphous Polyester Resin Dispersion (A1)]

[0236] Ethylene glycol: 37 parts

[0237] Neopentyl glycol: 65 parts

[0238] 1,9-nonanediol: 32 parts

[0239] Terephthalic acid: 96 parts

[0240] The above materials were put into a flask and the temperature was raised to 200°C over 1 hour. After confirming that the reaction system was uniformly stirred, 1.2 parts of dibutyltin oxide was added. While distilling off the generated water, the temperature was raised to 240°C over 6 hours. Stirring was continued at 240°C for 4 hours to obtain an amorphous polyester resin (acid value 9.4 mgKOH / g, weight average molecular weight 13,000, glass transition temperature 62°C). The amorphous polyester resin was kept in a molten state and conveyed to an emulsifier (Cavitron CD1010, Eurotec) at a rate of 100 g per minute. A 0.37% concentration of dilute ammonia water prepared by diluting the reagent ammonia water with ion exchange water was added to a tank, heated to 120°C using a heat exchanger, and conveyed to the emulsifier at a rate of 0.1 liter per minute together with the amorphous polyester resin. The emulsifier was operated at a rotor rotation speed of 60 Hz and a pressure of 5 kg / cm 2 The reaction mixture was operated under the conditions of , to obtain an amorphous polyester resin dispersion (A1) having a volume average particle size of 160 nm and a solid content of 20%.

[0241] [Preparation of Crystalline Polyester Resin Dispersion (C1)]

[0242] Decanediol: 81 parts

[0243] Hexanediol: 47 parts

[0244] The above materials were placed in a flask and the temperature was raised to 160°C over 1 hour. After confirming uniform stirring within the reaction system, 0.03 parts of dibutyltin oxide was added. While distilling off the generated water, the temperature was raised to 200°C over 6 hours and stirring was continued at 200°C for 4 hours. The reaction solution was then cooled, solid-liquid separation was performed, and the solid matter was dried at 40°C under reduced pressure to obtain a crystalline polyester resin (C1) (melting point 64°C, weight-average molecular weight 15,000).

[0245] Crystalline polyester resin (C1): 50 parts

[0246] Anionic surfactant (Neogen RK, manufactured by Daiichi Kogyo Chemical Co., Ltd.): 2 parts

[0247] Ion exchange water: 200 parts

[0248] The above materials were heated to 120°C, fully dispersed using a homogenizer (ULTRA-TURRAXT50, IKA), and then dispersed using a pressure-dispensing homogenizer. After the volume average particle size reached 180 nm, the particles were recovered to obtain a crystalline polyester resin dispersion (C1) with a solid content of 20%.

[0249] [Preparation of Release Agent Particle Dispersion (W1)]

[0250] Paraffin wax (HNP-9 manufactured by Nippon Seira Co., Ltd.): 100 parts

[0251] Anionic surfactant (Neogen RK, manufactured by Daiichi Kogyo Chemical Co., Ltd.): 1 part

[0252] Ion exchange water: 350 parts

[0253] The above materials were mixed, heated to 100°C, and dispersed using a homogenizer (ULTRA-TURRAXT50 manufactured by IKA). The mixture was then dispersed using a pressure-dispensing Gaulin homogenizer to obtain a release agent particle dispersion containing release agent particles with a volume average particle size of 200 nm. Ion-exchanged water was added to this release agent particle dispersion to adjust the solids content to 20%. This was designated release agent particle dispersion (W1).

[0254] [Preparation of Colorant Particle Dispersion (K1)]

[0255] Carbon black (Regal 330 manufactured by Cabot Corporation): 50 parts

[0256] Anionic surfactant (Neogen RK, manufactured by Daiichi Kogyo Chemical Co., Ltd.): 5 parts

[0257] Ion exchange water: 195 parts

[0258] The above materials were mixed and dispersed using an Ultimaizer (manufactured by Sugino Machine Co., Ltd.) at 240 MPa for 10 minutes to obtain a colorant particle dispersion (K1) having a solid content of 20%.

[0259] [Production of Toner Particles]

[0260] Ion exchange water: 200 parts

[0261] Amorphous polyester resin dispersion (A1): 150 parts

[0262] Crystalline polyester resin dispersion (C1): 10 parts

[0263] Release agent particle dispersion (W1): 10 parts

[0264] Colorant particle dispersion (K1): 15 parts

[0265] Anionic surfactant (TaycaPower): 2.8 parts

[0266] The above materials were placed in a round stainless steel flask, 0.1N nitric acid was added to adjust the pH to 3.5, and then an aqueous solution of polyaluminum chloride (30% powder, manufactured by Oji Paper Co., Ltd.) was added, obtained by dissolving 2 parts of polyaluminum chloride in 30 parts of ion-exchanged water. After dispersion at 30°C using a homogenizer (ULTRA-TURRAXT50 manufactured by IKA), the mixture was heated to 45°C in a heating oil bath and maintained until the volume average particle size reached 4.9 μm. Next, 60 parts of the amorphous polyester resin dispersion (A1) were added and maintained for 30 minutes. Then, after the volume average particle size reached 5.2 μm, 60 parts of the amorphous polyester resin dispersion (A1) were further added and maintained for 30 minutes. Then, 20 parts of a 10% aqueous solution of NTA (nitrilotriacetic acid) metal salt (Chelest 70, manufactured by Chelest Co., Ltd.) were added, and the pH was adjusted to 9.0 by adding a 1N aqueous solution of sodium hydroxide. Then, 1 part of anionic surfactant (Tayca Power) was added, and the mixture was heated to 85°C while being stirred and maintained for 5 hours. The mixture was then cooled to 20°C at a rate of 20°C / min. The mixture was filtered, thoroughly washed with ion-exchanged water, and dried to obtain toner particles (1) having a volume average particle size of 5.7 μm and an average circularity of 0.971.

[0267] <Production of Layered Compound Particles>

[0268] [Production of melamine cyanurate granules]

[0269] Commercially available melamine cyanurate (MC-4500, manufactured by Nissan Chemical Co., Ltd.) was pulverized with a jet mill and classified to obtain melamine cyanurate particles (1) to (4). "MC" in Table 1 means melamine cyanurate.

[0270] [Production of Boron Nitride Particles]

[0271] Commercially available boron nitride particles were pulverized with a jet mill and classified. "BN" in Table 1 means boron nitride.

[0272] [Preparation of Molybdenum Disulfide Particles]

[0273] Commercially available molybdenum disulfide particles were pulverized with a jet mill and classified. "MoS2" in Table 1 means molybdenum disulfide.

[0274] <Production of Silica Particles>

[0275] Hydrophobic fumed silica particles treated with hexamethyldisilazane for hydrophobization and hydrophobic sol-gel silica particles treated with hexamethyldisilazane for hydrophobization are prepared. The hydrophobic fumed silica particles and the hydrophobic sol-gel silica particles are classified as needed and mixed to obtain silica particles (1) to (7) having adjusted number ratios and mass ratios of irregularly shaped silica particles.

[0276] <Carrier Preparation>

[0277] 14 parts of toluene, 2 parts of styrene-methyl methacrylate copolymer (polymerization mass ratio 90:10, weight-average molecular weight 80,000), and 0.2 parts of carbon black (Cabot R330) were mixed and stirred for 10 minutes using a stirrer to prepare a dispersion. The dispersion and 100 parts of ferrite particles (volume-average particle size 36 μm) were then placed in a vacuum degassing kneader and stirred at 60°C for 30 minutes. The mixture was then degassed under reduced pressure while heating and dried to obtain a carrier.

[0278] <Example 1>

[0279] 100 parts by mass of toner particles (1), 0.5 parts by mass of melamine cyanurate particles (1), and 1.82 parts by mass of silica particles (1) were placed in a sample mill and mixed at 10,000 rpm for 30 seconds. The mixture was then sieved using a vibrating sieve with a mesh size of 45 μm to produce a toner having a volume average particle size of 5.7 μm. The toner and carrier were placed in a V-type blender at a ratio of toner:carrier = 5:95 (mass ratio) and stirred for 20 minutes to obtain a developer.

[0280] <Examples 2 to 16, Comparative Examples 1 and 2>

[0281] A toner and a developer were obtained in the same manner as in Example 1 except that the type or amount of melamine cyanurate particles or the type or amount of silica particles were changed.

[0282] <Performance Evaluation>

[0283] The fixing device was modified using ApeosPort-IV C5575 (manufactured by Fuji Xerox Co., Ltd.), and a peeling test was performed in the following procedure.

[0284] -Preparation of the fixing unit-

[0285] (1) A separation claw of the same type as that used in ApeosPort-IV C5575 (manufactured by Fuji Xerox Co., Ltd.) was prepared, the oblique line portion of the separation claw was cut off, and a strain gauge (KFG-1-120-C1-16 manufactured by Kyowa Electric Co., Ltd.) was bonded.

[0286] (2) Use weights to find the relationship between the load applied to the separation claw and the strain of the claw, and create a conversion curve.

[0287] (3) Cut a groove with a width of 4 mm and a depth of 1 mm along the circumference of the central part of the heating roller.

[0288] (4) Place the heating roller that has undergone the above processing in a modified fusing unit of ApeosPort-IV C5575 (manufactured by Fuji Xerox Co., Ltd.), and further fix the separation claw to the fusing unit body in such a way that the front end part is inserted into the groove and does not contact the heating roller body.

[0289] -Measurement of peeling force-

[0290] Pass the unfused image through the modified fusing unit of ApeosPort-IV C5575 (manufactured by Fuji Xerox Co., Ltd.) set up according to the previous item (4) in an environment with a temperature of 28°C and a relative humidity of 85%. Use a dynamic strain gauge ((manufactured by) Kyowa Electronic Instruments Co., Ltd.: DMP-911B) connected to a strain gauge to read the strain of the separation claw at this time, and find the peeling force according to the conversion curve made in the previous item (2). The judgment criteria for the peeling force F are as follows.

[0291] F ≦ 20 gf: The fixed body peels off from the fusing roller without any problems.

[0292] 20 gf < F ≦ 35 gf: Image unevenness defects occur under the peeling stress, but it is at a level that is not a problem in practical use.

[0293] 35 gf < F ≦ 50 gf: The peeling is unstable, and part of it winds around the fusing roller.

[0294] 50 gf < F: The fixed body cannot peel off and winds around the fusing roller entirely.

[0295]

Claims

1. A toner for developing electrostatic images, wherein: The toner contains toner particles, melamine cyanurate particles and inorganic particles. The proportion of irregular-shaped inorganic particles having a roundness of 0.5 to 0.9 and a particle size of 0.015 μm to 0.350 μm relative to the entire inorganic particles is 2% by number to 70% by number. The mass-based ratio Ma / Mb of the content Ma of the melamine cyanurate particles to the content Mb of the irregular-shaped inorganic particles is 0.004 or more and 1.0 or less.

2. The electrostatic image developing toner according to claim 1, wherein The ratio of the irregular-shaped inorganic particles to the total amount of the inorganic particles is 20% by number or more and 65% by number or less.

3. The electrostatic image developing toner according to claim 1, wherein The ratio Ma / Mb is not less than 0.05 and not more than 0.

6.

4. The electrostatic image developing toner according to claim 1 or 2, wherein The content of the melamine cyanurate particles is 0.01% by mass or more and 2.0% by mass or less based on the total mass of the electrostatic image developing toner.

5. The electrostatic image developing toner according to claim 1 or 2, wherein The irregularly shaped inorganic particles include irregularly shaped silica particles.

6. The electrostatic image developing toner according to claim 1 or 2, wherein The number average particle size of the inorganic particles as a whole is 0.015 μm or more and 0.350 μm or less. The average circularity of the inorganic particles as a whole is 0.8 or more. 7 . An electrostatic image developer comprising the electrostatic image developing toner according to claim 1 . 8 . A toner cartridge that is detachably mounted in an image forming apparatus, the toner storing the electrostatic image developing toner according to claim 1 .

9. A process cartridge detachably mounted in an image forming apparatus, comprising a developing mechanism storing the electrostatic image developer according to claim 7 and developing an electrostatic image formed on a surface of an image holding member into a toner image using the electrostatic image developer.

10. An image forming apparatus comprising: Image holding body; a charging mechanism for charging the surface of the image holding member; an electrostatic image forming mechanism for forming an electrostatic image on the charged surface of the image holding member; a developing mechanism storing the electrostatic image developer according to claim 7 and developing the electrostatic image formed on the surface of the image holding member into a toner image using the electrostatic image developer; a transfer mechanism for transferring the toner image formed on the surface of the image holding member to the surface of the recording medium; as well as The fixing mechanism fixes the toner image transferred to the surface of the recording medium.

11. An image forming method comprising: Charging, charging the surface of the image holding body; Electrostatic image formation, forming an electrostatic image on the charged surface of the image holding member; developing the electrostatic image formed on the surface of the image holding member into a toner image using the electrostatic image developer according to claim 7; Transferring the toner image formed on the surface of the image holding member to the surface of the recording medium; as well as Fixing is to fix the toner image transferred to the surface of the recording medium.

Images