Method for producing toner

Abstract

To provide a method for manufacturing a toner having high cleaning property and image density stability.SOLUTION: Wherein the toner particles have a solidity of at least 0.90 and not more than 0.99, the metallic titanate compound particles have a shear adhesive force of at least 4000Pa and not more than 10000Pa, and the mixing step uses a mixing apparatus having a mixing tank and a rotatable stirring blade provided in the mixing tank, stirring and mixing the material to be treated by rotating the stirring blade at a tip peripheral speed of 30m / s or more and 70m / s or less in the mixing tank.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a toner used in an electrophotographic system, an electrostatic recording system, an electrostatic printing system, and a toner jet system. [Background technology]

[0002] Electrophotographic copying machines have become widespread and are increasingly being applied to the printing market. In recent years, the print-on-demand (POD) field has grown, and the printing market has placed even higher demands on toner. When considering the application of toner-based image formation methods to the POD market, it is necessary to be able to consistently produce high-quality print results even when printing large quantities at high speed over long periods of time. Patent Document 1 discloses technology relating to strontium titanate-based fine particles treated with silicone oil or alkoxysilane as an external toner additive, which can be used as a charge control agent for toner with excellent dispersibility, environmental friendliness, and charging properties, or as an abrasive to prevent filming on photoreceptors and image deletion. Patent Document 2 discloses that a two-component developer containing strontium titanate particles that have been surface-treated with a hydrophobic treatment agent is less likely to cause pinholes in the photoreceptor and is excellent in image density stability and fogging resistance. Patent Document 3 discloses a developer that satisfies both cleaning properties and image quality by using a toner having a specific degree of envelopment. Patent Document 4 discloses a process cartridge and an image forming method in which a toner has a uniaxial collapse stress within a specific range, thereby maintaining high print image density and preventing image defects even when paper is continuously fed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-137208 [Patent Document 2] Japanese Patent Application Publication No. 2020-129029 [Patent Document 3] Japanese Patent Application Laid-Open No. 2008-40465 [Patent Document 4] Japanese Patent Application Laid-Open No. 2016-38589 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when a system with a print speed faster than conventional systems is operated continuously for 24 hours, especially when images are formed at low coverage (low image ratio), there is a problem of toner fusing to the photoreceptor or slipping through the cleaning blade. With low coverage, less residual toner is supplied to the photoreceptor for cleaning, and the toner remaining in the cleaning area is less replaced. Therefore, heat generated by the friction between the cleaning blade and the photoreceptor deteriorates the remaining toner, making it more likely to fuse to the photoreceptor or slip through the blade. In particular, the higher the speed, the greater the amount of heat generated, making it more likely to cause image defects due to toner fusing to the photoreceptor. The object of the present invention is to solve the above-mentioned problems and achieve stable cleaning properties and image quality, i.e., to provide a method for producing a toner that does not cause toner fusion to a photoreceptor or slip through a cleaning blade, and that has excellent chargeability, environmental stability, image density stability, and fogging resistance. [Means for solving the problem]

[0005] The present invention provides a toner manufacturing method including a mixing step of stirring and mixing toner particles containing a binder resin and a colorant with a processing target containing metal titanate compound particles, the toner particles have a density of 0.90 or more and 0.99 or less; the metal titanate compound particles have a shear adhesive strength of 4000 Pa or more and 10000 Pa or less, The mixing step is a method for producing a toner, characterized in that the material to be treated is stirred and mixed by using a mixing device having a mixing tank and a rotatable stirring blade provided in the mixing tank, and rotating the stirring blade in the mixing tank at a tip peripheral speed of 30 m / s or more and 70 m / s or less. [Effects of the Invention]

[0006] The present invention can provide a method for producing a toner that does not cause toner fusion to a photoreceptor or slip through a cleaning blade, and that has excellent chargeability, environmental stability, image density stability, and fogging resistance. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram of a mechanical pulverizer suitable for obtaining toner particles according to the present invention. [Figure 2] 1 is a schematic diagram of a pulverizing system having a jet mill suitable for obtaining toner particles according to the present invention. [Figure 3] 1 is a schematic diagram of a thermal processing apparatus suitable for thermally processing toner particles. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Meaning and Features of the Present Invention] The toner manufacturing method of the present disclosure is a toner manufacturing method including a mixing step of stirring and mixing toner particles containing a binder resin and a colorant with a processing target containing metal titanate compound particles, the toner particles have a density of 0.90 or more and 0.99 or less; the metal titanate compound particles have a shear adhesive strength of 4000 Pa or more and 10000 Pa or less, The mixing step is characterized in that it is a step of stirring and mixing the material to be treated by using a mixing device having a mixing tank and a rotatable stirring blade provided in the mixing tank, and rotating the stirring blade in the mixing tank at a tip peripheral speed of 30 m / s or more and 70 m / s or less.

[0009] According to the toner manufacturing method of the present invention, it is possible to provide a toner that does not melt onto a photoreceptor (hereinafter also referred to as a drum) or slip through a cleaning blade, and that has excellent chargeability, environmental stability, image density stability, and fogging resistance.

[0010] The reason why the effects of the present invention are obtained is not clear, but the present inventors assume the mechanism as follows.

[0011] In the present invention, it is important that the density of the toner particles is 0.90 or more and 0.99 or less, the shear adhesive strength of the metal titanate compound is 4000 Pa or more and 10000 Pa or less, and the peripheral speed of the tip of the stirring blade in the mixing process is 30 m / s or more and 70 m / s or less.

[0012] By ensuring that each value is within the above range, agglomerates of the metal titanate compound, which have aggregated due to a specific shear adhesive force, can be adequately loosened by the stirring force of the stirring blade during the mixing process, and can be selectively fixed to the convex portions of toner particles, which have uneven particle surfaces due to a specific density.It is believed that by selectively fixing the metal titanate compound with a specific shear adhesive force to the convex portions of toner particles at a high concentration, it is possible to prevent the toner from fusing to the photoreceptor and slipping through the cleaning blade.

[0013] This will be explained in detail below.

[0014] Due to their cohesive strength, metal titanate compounds generally form large agglomerates. These large agglomerates are broken down during the mixing process with toner particles and gradually become smaller. The small agglomerates of the metal titanate compound first adhere to the recesses of the toner particles. The toner particles, with small agglomerates adhering to the recesses, then repeatedly collide with the stirring blades and the inner wall of the mixing vessel. In this situation, typical metal titanate compounds often either diffuse and adhere to the entire toner particle, or further aggregate in the recesses. However, after extensive research, the inventors have found that metal titanate compounds with specific shear adhesive strength can be selectively and highly concentratedly attached to the protruding portions of toner particles. While the detailed mechanism is unclear, the inventors speculate as follows: When the adhesive strength of the metal titanate compound falls within the range of the present invention, a good balance is achieved between the cohesive strength between the metal titanate compounds and the adhesive strength with the toner particles. As a result, the edges of the recesses and protruding portions on the toner particle surface crush the agglomerates of the metal titanate compound, allowing them to adhere to the protruding portions of the toner particles.

[0015] When toner particles come into contact with the surface of the photoreceptor or the carrier, the concave portions are less likely to come into direct contact, while the convex portions are more likely to come into contact. The metal titanate compound is adhered to the convex portions of the surface of the toner particles of the present invention at a high concentration. As a result, in the area where the transfer residual toner present on the surface of the photoreceptor comes into direct contact with the surface of the photoreceptor, the metal titanate compound is interposed between the photoreceptor surface and the toner particles, which serves to reduce the adhesive force between the toner and the drum.

[0016] Due to this function, in the process of cleaning residual toner from the photoreceptor surface, the metal titanate compound acts to slide the toner off the photoreceptor surface, thereby suppressing heat generation in the cleaning area and deterioration of the accumulated toner, thereby preventing toner from fusing to the photoreceptor and slipping through the cleaning blade.

[0017] Furthermore, by selectively adhering the metal titanate compound to the convex portions of the toner particles, the carrier and the metal titanate compound come into contact with each other frequently in the developer, enabling the developer to exhibit excellent charging properties, environmental stability, and fogging resistance.

[0018] Furthermore, since the metal titanate compound is fixed to the toner particles at a high concentration, it is difficult to be embedded in the toner particles even after long-term use, and the image density is excellently stable.

[0019] (Shear adhesion strength of metal titanate compounds) It is important that the shear adhesive strength of the metal titanate compound according to the present invention is 4000 Pa or more and 10000 Pa or less, preferably 4000 Pa or more and 8000 Pa or less, and more preferably 5000 Pa or more and 7000 Pa or less.

[0020] When the shear adhesive strength of the metal titanate compound is within the above range, the cohesive strength of the metal titanate compound is optimized, making it easier for agglomerates of the metal titanate compound to be optimally broken down during the mixing process, allowing the metal titanate compound to adhere selectively to the convex portions of the toner particles at a high concentration. As a result, the metal titanate compound on the convex portions of the toner particles effectively reduces the adhesive strength between the toner and the photoreceptor. Furthermore, the metal titanate compound simultaneously acts to allow the toner to slide, leading to the prevention of toner retention and slippage in the cleaning section.

[0021] When the shear adhesive strength of the metal titanate compound is less than 4000 Pa, the cohesive strength of the metal titanate compound is low, and the agglomerates of the metal titanate compound tend to break apart easily during the mixing process. As a result, the metal titanate compound is uniformly dispersed on the surface of the toner particles and does not adhere to the protrusions in high concentrations. This reduces the amount of metal titanate compound that comes into contact with the photoreceptor when the toner and the photoreceptor come into contact during photoreceptor cleaning. As a result, the metal titanate compound does not reduce the adhesive strength between the toner and the photoreceptor, and instead increases the adhesive strength between the toner and the photoreceptor, making it easier for the toner to accumulate in the cleaning area and causing the toner to melt onto the photoreceptor or slip through.

[0022] On the other hand, if the shear adhesive strength of the metal titanate compound is greater than 10,000 Pa, the cohesive strength of the metal titanate compound is so great that agglomerates of the metal titanate compound are difficult to break apart during the mixing process and tend to remain as agglomerates. As a result, when the toner and the photoconductor come into contact with each other during photoconductor cleaning, the photoconductor and the metal titanate compound are less likely to come into contact. This results in a high adhesive strength between the toner and the photoconductor, which can lead to toner retention in the cleaning section and toner melting onto the photoconductor or slipping through.

[0023] (Toner particle density) In order to selectively fix the metal titanate compound to the protrusions on the surface of the toner particles, it is necessary for the shape of the toner particles to have a specific density.

[0024] The toner particles according to the present invention have a density of 0.90 or more and 0.99 or less, preferably 0.91 or more and 0.97 or less, and more preferably 0.93 or more and 0.95 or less.

[0025] The density is a value expressed by the following formula, calculated from the area of ​​a toner particle and the area enclosed by the envelope, and the density was determined using a measuring device "FPIA-3000" (manufactured by Sysmex Corporation). Density = (area of ​​toner particle) / (area of ​​toner particle surrounded by envelope)

[0026] The density is a quantity that takes a value between 0 and 1, and the smaller the value, the more recesses there are and the more intricate the shape becomes. The density has the same meaning as the envelopment degree. The method for measuring the density of toner particles will be described in detail later, but the density in the present invention is the average density based on data measured on 3,000 toner particles.

[0027] When the density of the toner particles is within the above range, the metal titanate compound tends to selectively adhere to the convex portions of the toner particles at a high concentration during the mixing process. As a result, during the photoreceptor cleaning process, when the transfer residual toner comes into contact with the photoreceptor, the metal titanate compound has the effect of reducing the adhesive force between the toner and the photoreceptor. The metal titanate compound also serves to make the toner slippery, preventing the toner from fusing to the photoreceptor or slipping through the cleaning blade. Furthermore, a toner having excellent chargeability, environmental stability, image density stability, and fogging resistance can be obtained.

[0028] If the density of the toner particles is less than 0.90, the toner particles become more irregular in shape, making it difficult to selectively fix the metal titanate compound to the protruding portions of the toner particles.

[0029] On the other hand, when the density of toner particles is greater than 0.99, the toner particles become nearly spherical. Because there are almost no protrusions, it becomes impossible to adhere the metal titanate compound to the toner particle surface at a high concentration. Furthermore, toner particles that are nearly spherical may easily slip through the cleaning blade, and even if the metal titanate compound is adhered to the protrusions of the toner particles, sufficient effect may not be obtained.

[0030] (Tip peripheral speed of the stirring blade during the mixing process) It is important that the tip peripheral speed of the stirring blade in the mixing step according to the present invention is 30 m / s or more and 70 m / s or less, preferably 30 m / s or more and 60 m / s or less, and more preferably 40 m / s or more and 60 m / s or less.

[0031] When the peripheral speed of the stirring blade tip during the mixing process is within the above range, the agglomerates of the metal titanate compound can be adequately loosened, allowing the compound to selectively adhere to the protruding portions of the toner particles at a high concentration. As a result, during photoreceptor cleaning, the metal titanate compound is likely to reduce the adhesive force between the toner and the photoreceptor when they come into contact with each other. The metal titanate compound also acts to make the toner slide, preventing toner retention and preventing the toner from fusing to or slipping through the photoreceptor.

[0032] If the peripheral speed of the stirring blade tip during the mixing process is less than 30 m / s, the ability to break up clumps of the metal titanate compound is weak, making it difficult to selectively adhere the metal titanate compound to the protruding portions of the toner particles at a high concentration. As a result, during photoreceptor cleaning, the toner and the metal titanate compound cannot come into contact with each other when they come into contact with each other. This results in a high adhesion between the toner and the photoreceptor, causing the toner to accumulate in the cleaning area, which can lead to the toner fusing to the photoreceptor or slipping through.

[0033] When the peripheral speed of the tip of the agitator blade during the mixing process exceeds 70 m / s, clumps of the metal titanate compound tend to break down. The metal titanate compound then disperses and adheres uniformly to the surface of the toner particles. As a result, less of the metal titanate compound comes into contact with the photoreceptor during photoreceptor cleaning. The metal titanate compound does not reduce the adhesive strength between the toner and the photoreceptor. The adhesive strength between the toner and the photoreceptor is so high that the toner accumulates in the cleaning area, potentially causing the toner to melt onto the photoreceptor or slip through.

[0034] (Surface treatment with metal titanate compounds) The surface of the metal titanate compound of the present invention is preferably treated with a silane coupling agent.

[0035] By treating a metal titanate compound with a silane coupling agent, the degree of hydrophobicity can be increased and adhesion can be reduced, which in turn can prevent the toner from fusing to the photoreceptor and slipping through the cleaning blade, and can also provide a toner that is excellent in chargeability, environmental stability, image density stability, and fogging resistance.

[0036] The silane coupling agent is not particularly limited, but examples thereof include alkoxysilanes such as methoxysilane, ethoxysilane, and propoxysilane; halosilanes such as chlorosilane, bromosilane, and iodosilane; hydrosilanes; alkylsilanes; arylsilanes; vinylsilanes; acrylicsilanes; epoxysilanes; silyl compounds; siloxanes; silylureas; silylacetamides; and silane compounds having the same different substituents as these silane compounds.

[0037] Specific examples include trimethylsilane, trimethylchlorosilane, trimethylethoxysilane, dimethyldichlorosilane, methyltrichlorosilane, trialkoxyalkylsilane, allyldimethylchlorosilane, α-chloroethyltrichlorosilane, β-chloroethyltrichlorosilane, chloromethyldimethylchlorosilane, dimethyldiethoxysilane, dimethyldimethoxysilane, and hexamethyldisiloxane.

[0038] Alkyltrialkoxysilanes are particularly preferred from the viewpoints of hydrophobicity, chargeability, and cleaning properties. Among these, methyltriethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, isobutyltrimethoxysilane, n-hexyltrimethoxysilane, n-octyltriethoxysilane, etc. are preferably used. More preferably, the alkyl group has 3 to 6 carbon atoms, and isobutyltrimethoxysilane is even more preferred. The amount of silane coupling agent to be treated is preferably 0.1 to 40 parts by mass per 100 parts by mass of the substrate. More preferably, it is 1 to 20 parts by mass.

[0039] The surface of the metal titanate compound of the present invention is preferably treated with silicone oil.

[0040] By treating the metal titanate compound with silicone oil, the hydrophobicity is increased, and the silicone oil creates a lubricating effect between the drum and the toner, allowing the toner to slide. As a result, it is possible to suppress toner fusion to the photoreceptor and slippage through the cleaning blade, and it is possible to obtain a toner with excellent charging properties, environmental stability, image density stability, and fogging resistance.

[0041] The silicone oil is not particularly limited, but examples thereof include dimethyl silicone oil, alkyl-modified silicone oil, α-methylstyrene-modified silicone oil, chlorophenyl silicone oil, and fluorine-modified silicone oil.

[0042] The above silicone oil has a viscosity of 1.0 x 10 at 25°C. -4 m 2 / s or more 0.1m 2 / s or less is preferable. Preferably, it is 1.0 × 10 -3 m 2 / s or more 0.03m 2 / s or less is preferable. Conventional techniques can be used for the silicone oil treatment method. For example, a powder of a metal titanate compound and silicone oil are mixed using a mixer. Silicone oil is sprayed into the powder of a metal titanate compound using a sprayer; or silicone oil is dissolved or dispersed in a solvent or water and then mixed. Treatment methods are not limited to these. The amount of silicone oil to be treated is preferably 0.1 to 10 parts by mass per 100 parts by mass of the substrate. It is more preferably 1 to 5 parts by mass.

[0043] In the case of a primary particle diameter of 0.02 μm or more and 0.3 μm or less, it is preferable to coat the particles with a hydrophobic agent in an aqueous system, since this provides better dispersibility. The method for treating the particles in an aqueous system is not particularly limited, but a preferred method is to emulsify silicone oil in water using an emulsifier and then adsorb it onto a strontium titanate slurry.

[0044] The surface of the metal titanate compound of the present invention is preferably treated with both a silane coupling agent and a silicone oil. Treating the metal titanate compound with both of the above-mentioned treatment agents enhances the effect of suppressing toner fusion to the photoreceptor and slippage through the cleaning blade compared to surface treatment with either one of them. Furthermore, a toner with superior charging properties, environmental stability, image density stability, and fogging resistance can be obtained. In particular, it is preferable to treat the compound with a silane coupling agent followed by a silicone oil treatment.

[0045] (Particle size and material of metal titanate compound) The metal titanate compound of the present invention preferably has a number average particle size of 10 nm or more and 500 nm or less, more preferably 10 nm or more and 100 nm or less, and even more preferably 10 nm or more and 50 nm or less.

[0046] When the particle size of the metal titanate compound is within the above range, the toner easily adheres to the protrusions on the toner particle surface, which prevents the toner from fusing to the photoreceptor or slipping through the cleaning blade, and also provides a toner with excellent chargeability, environmental stability, image density stability, and fogging resistance.

[0047] The metal titanate compound of the present invention is preferably strontium titanate particles, calcium titanate particles, magnesium titanate particles, or zinc titanate particles, more preferably strontium titanate particles.

[0048] By using the above-mentioned metal titanate compound, it is possible to prevent the toner from fusing to the photoreceptor and slipping through the cleaning blade, and further to obtain a toner that is excellent in chargeability, environmental stability, image density stability, and fogging resistance.

[0049] (Silica fine particles) The toner of the present invention may contain silica fine particles, which provides better chargeability, environmental stability, image density stability, and fogging resistance.

[0050] The number average particle diameter of the silica fine particles is preferably 50 nm or more and 200 nm or less, and more preferably 60 nm or more and 150 nm or less.

[0051] When the silica fine particles have a particle size within the above range, they are easily fixed to the toner particle surface and are not easily released, and therefore, in drum cleaning, the silica fine particles do not contaminate the drum and exhibit excellent cleaning properties.

[0052] [Toner raw materials] Next, the raw materials of the toner used in the present invention will be described.

[0053] <Metal titanate compounds> [Manufacturing method] The methods for producing particles of strontium titanate, calcium titanate, titanium magnesium and zinc titanate, which are preferred as the metal titanate compounds used in the present invention, will now be described.

[0054] Strontium titanate: The method for producing strontium titanate is not particularly limited, but includes a wet method and a sintering method, with the wet method being more preferred due to its high surface treatment efficiency.

[0055] The titanate compound particles may contain a dopant. The dopant for the strontium titanate particles is not particularly limited, but is preferably lanthanoid, silica, aluminum, magnesium, calcium, barium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, niobium, molybdenum, ruthenium, palladium, indium, antimony, tantalum, tungsten, rhenium, iridium, platinum, bismuth, yttrium, zirconium, niobium, silver, or tin. As the lanthanoid, lanthanum and cerium are preferred. Among these, lanthanum and silica are more preferred because they have a size that makes them easy to incorporate into the crystal structure.

[0056] The strontium titanate particles of the present invention can be obtained, for example, by a normal pressure heating reaction method. In this method, a mineral acid peptized product of a hydrolyzed titanium compound is used as the titanium oxide source, and a water-soluble acidic metal compound is used as the strontium metal source. The mixture is reacted with an aqueous alkali solution at 60°C or higher, followed by acid treatment.

[0057] (Normal pressure heating reaction method) The titanium oxide source is a mineral acid peptized product of a titanium compound hydrolyzate. Metatitanic acid with an SO3 content of 1.0 mass% or less, preferably 0.5 mass% or less, obtained by a sulfuric acid method, is preferably peptized by adjusting the pH to 0.8 to 1.5 with hydrochloric acid. Metatitanic acid with an SO3 content of more than 1.0 mass% is not preferred because it does not peptize well.

[0058] As the source of the metal other than titanium, nitrates, hydrochlorides, etc. of the metal can be used.

[0059] As the nitrate, for example, strontium nitrate can be used. As the hydrochloride, for example, strontium chloride can be used. Among these, when strontium nitrate or hydrochloride is used for production, the resulting strontium titanate particles have a perovskite crystal structure, which is preferable in that the environmental stability of charging is further improved.

[0060] As the alkaline aqueous solution, a caustic alkali can be used, but among these, an aqueous sodium hydroxide solution is preferred.

[0061] In the above-mentioned production method, factors that affect the particle size of the obtained strontium titanate particles include the mixing ratio of the titanium oxide source and the strontium source during the reaction, the concentration of the titanium oxide source at the beginning of the reaction, the temperature and addition rate when adding the alkaline aqueous solution, etc., and these can be appropriately adjusted to obtain the desired particle size and particle size distribution. Note that, in order to prevent the formation of carbonate during the reaction process, it is preferable to prevent the inclusion of carbon dioxide gas, for example by carrying out the reaction under a nitrogen gas atmosphere.

[0062] In the above-mentioned production method, factors that affect the particle size distribution of the resulting strontium titanate particles include the pH when the metatitanic acid is peptized with hydrochloric acid, the concentration of the titanium oxide source at the beginning of the reaction, the addition rate and reaction time when the alkaline aqueous solution is added, and the stirring conditions. In particular, if the reaction is stopped by suddenly lowering the temperature of the system after the addition of the alkaline aqueous solution, for example by immersing the system in ice water, the reaction can be stopped forcibly before crystal growth reaches saturation, which makes it easier to broaden the particle size. In addition, the particle size distribution tends to become broader by making the reaction system non-uniform by lowering the stirring speed or changing the stirring method.

[0063] The mixing ratio of the titanium oxide source and strontium source during the reaction is preferably 0.9 to 1.4, more preferably 1.05 to 1.20, in terms of the molar ratio MxO / TiO2, where M represents a metal other than titanium and its oxide is MxO (where x is 1 when M is an alkaline earth metal and 2 when M is an alkali metal). When the MxO / TiO2 molar ratio is 1 or less, the reaction product is likely to contain not only metal titanate but also unreacted titanium oxide. Because metal sources other than titanium have relatively high solubility in water, while the titanium oxide source has low solubility in water, when the MxO / TiO2 molar ratio is 1 or less, the reaction product is likely to contain not only metal titanate but also unreacted titanium oxide. The concentration of the titanium oxide source at the start of the reaction is preferably 0.05 mol / L to 1.3 mol / L, more preferably 0.08 mol / L to 1.0 mol / L, in terms of TiO2.

[0064] When adding the alkaline aqueous solution, a temperature above 100°C requires a pressure vessel such as an autoclave, and therefore a practical range of 60°C to 100°C is appropriate. Furthermore, the slower the rate of addition of the alkaline aqueous solution, the larger the particle size of the resulting strontium titanate particles, and the faster the rate of addition, the smaller the particle size of the resulting strontium titanate particles. The rate of addition of the alkaline aqueous solution is preferably 0.001 to 1.2 equivalents / h, and more preferably 0.002 to 1.1 equivalents / h, relative to the amount of raw material added, and can be adjusted appropriately depending on the particle size desired.

[0065] (acid treatment) In the manufacturing method of the present invention, it is preferable to further acid-treat the strontium titanate particles obtained by the atmospheric heating reaction. When synthesizing strontium titanate particles by the atmospheric heating reaction, if the mixing ratio of the titanium oxide source and the strontium source (MxO / TiO2) exceeds 1.0 in molar ratio, the unreacted strontium source remaining after the reaction reacts with carbon dioxide in the air to produce impurities such as metal carbonates. Furthermore, if impurities such as metal carbonates remain on the surface, the impurities will prevent uniform coating of the organic surface treatment agent during organic surface treatment to impart hydrophobicity. Therefore, it is preferable to perform an acid treatment to remove the unreacted metal source after adding an alkaline aqueous solution.

[0066] In the acid treatment, it is preferable to use hydrochloric acid to adjust the pH to 2.5 to 7.0, more preferably 4.5 to 6.0. As the acid, in addition to hydrochloric acid, nitric acid, acetic acid, etc. can be used for the acid treatment. The use of sulfuric acid is not preferable because it generates metal sulfates that have low solubility in water.

[0067] (sintering method) The strontium titanate particles of the present invention can also be obtained by, for example, a sintering method.

[0068] Specifically, for example, first, an equimolar amount of SrCl2 to TiO2 is added to metatitanic acid slurry obtained by a sulfuric acid method or the like, and then CO2 gas is blown in at twice the molar amount of TiO2 while simultaneously adding aqueous ammonia. The resulting precipitate is then washed with water, dried at 110°C for one day, and then sintered at 900°C to obtain strontium titanate particles with a number-average particle size of 200 nm to 500 nm. The resulting strontium titanate particles can be qualitatively analyzed by X-ray diffraction to identify any remaining strontium carbonate.

[0069] The strontium carbonate-containing strontium titanate particles thus obtained are then immersed in a strong acid solution to elute the strontium carbonate. It is preferable to stir the particles during immersion, and it is also preferable to wash and dry the particles after immersion.

[0070] Calcium titanate: The calcium titanate particles of the present invention can be obtained, for example, by a high-pressure liquid-phase reaction method, which comprises mixing a monobasic acid peptized product of a titanium compound hydrolysate, a water-soluble calcium-containing compound, sugar, and an alkali, heating the mixture to 100°C or higher and 270°C or lower to synthesize fine particles mainly composed of calcium titanate, and then subjecting the resulting fine particles mainly composed of calcium titanate to a decalcification treatment.

[0071] (High-pressure liquid phase reaction method) The monobasic acid peptized product of the titanium compound hydrolysate is preferably metatitanic acid obtained by the sulfuric acid method, with an SO₃ content of 15 g / kg or less, preferably 10 g / kg or less, and peptized by adjusting the pH to 0.8 to 1.5 with hydrochloric acid. This allows calcium titanate particles with a narrow particle size distribution to be obtained. If the SO₃ content in the metatitanic acid exceeds 15 g / kg, peptization will not proceed. In addition to hydrochloric acid, other monobasic acids such as nitric acid, hydrogen bromide, hydrogen iodide, formic acid, and acetic acid can also be used. Preferred calcium-containing water-soluble compounds include calcium nitrate, calcium chloride, and calcium hydroxide. Caustic alkalis can be used as the alkali, with sodium hydroxide being preferred.

[0072] Suitable sugars include monosaccharides and disaccharides such as glucose, fructose, glyceraldehyde, maltose, lactose, arabinose, cellobiose, sucrose, and trehalose. Adding these sugars to the high-pressure liquid-phase reaction method can make the calcium titanate particles synthesized granular and reduce their particle size. The particles constituting the powder of the present invention may contain carbon derived from these sugars. The carbon content of the powder particles of the present invention is preferably in the range of 10.0 g / kg to 50.0 g / kg, more preferably 15.0 g / kg to 40.0 g / kg. The carbon content of the calcium titanate powder particles can be adjusted by the amount of sugar added during the high-pressure liquid-phase reaction.

[0073] In the above-mentioned production method, factors that affect the shape and particle size of the obtained particles mainly composed of calcium titanate include the concentration and mixing ratio of the raw materials in the high-pressure liquid phase reaction method, the alkali concentration, and the reaction temperature.

[0074] The mixing ratio of the monobasic acid peptized product of the titanium compound hydrolysate to the calcium-containing water-soluble compound during the high-pressure liquid-phase reaction is preferably a Ca / Ti molar ratio of 1.00 to 1.60, and more preferably 1.10 to 1.50. Because the monobasic acid peptized product of the titanium compound hydrolysate has low solubility in water, a Ca / Ti molar ratio of less than 1.00 tends to result in the reaction product consisting not only of calcium titanate particles but also unreacted titanium oxide remaining. The concentration of the monobasic acid peptized product of the titanium compound hydrolysate during the high-pressure liquid-phase reaction is preferably 0.5 mol / L to 1.5 mol / L, more preferably 0.7 mol / L to 1.4 mol / L, in terms of Ti.

[0075] The sugar concentration during the high-pressure liquid-phase reaction should be 0.030 mol / L to 0.500 mol / L, preferably 0.050 mol / L to 0.350 mol / L. If the concentration is outside this range, titanium dioxide tends to remain, and if it is less than 0.030 mol / L, fine calcium titanate cannot be obtained.

[0076] The alkali concentration during the high-pressure liquid phase reaction is preferably 0.1 mol / L or more, more preferably in the range of 0.5 mol / L or more and 2.3 mol / L or less.

[0077] The temperature during the high-pressure liquid-phase reaction is 100°C or higher and 270°C or lower, and more preferably 120°C or higher and 200°C or lower. If the temperature is lower than 100°C, it becomes difficult to obtain fine calcium titanate, and if the temperature exceeds 270°C, the pressure increases and the equipment cost of a reaction vessel that can withstand the pressure becomes high. The reaction time varies depending on the temperature, but is preferably 1 hour or higher and 20 hours or lower. The reactor is not particularly limited as long as it can achieve the specified temperature and pressure. For example, a conventional autoclave device can be used.

[0078] (Decalcification treatment) After calcium titanate is synthesized by the high-pressure liquid-phase reaction method, it is subjected to a decalcification treatment. If the Ca / Ti molar ratio of the calcium titanate powder obtained by the high-pressure liquid-phase reaction exceeds 1.00, the unreacted calcium remaining after the reaction reacts with carbon dioxide in the air, producing impurity particles such as calcium carbonate. If these impurity particles remain in the powder, the particle size distribution of the powder becomes broad. Furthermore, if impurities such as calcium carbonate remain on the particle surface, the impurities prevent a uniform coating of the surface treatment agent during surface treatment to impart hydrophobicity. Therefore, a decalcification treatment is performed to remove the unreacted calcium.

[0079] Furthermore, in the decalcification treatment, it is preferable to adjust the molar ratio of calcium to titanium in the calcium titanate powder to 0.50 or more and 0.90 or less to prevent the formation of titanium dioxide, thereby making the particle surface calcium deficient compared to the stoichiometric ratio of calcium to titanium in calcium titanate. This molar ratio is more preferably 0.60 or more and 0.80 or less. This allows for a more uniform coating of the organic surface treatment agent, thereby imparting good charge stability and fluidity to the toner.

[0080] In the decalcification treatment, it is preferable to use hydrochloric acid to adjust the pH to between 2.5 and 7.0, more preferably between 4.5 and 6.0. In addition to hydrochloric acid, other acids such as nitric acid and acetic acid can be used for the decalcification treatment. However, using sulfuric acid is not preferable because it generates calcium sulfate, which has low solubility in water.

[0081] Magnesium titanate: The titanium magnesium oxide particles of the present invention can be obtained by mixing titanium oxide or a precursor that will become titanium oxide upon calcination with magnesium oxide or a precursor that will become magnesium oxide upon calcination, and calcining the mixed raw material in a chlorine-containing atmosphere, which is an atmosphere containing one kind of gas selected from the following (1) to (3): (1) Hydrogen chloride (2) A component prepared from molecular chlorine and water vapor (3) Molecular chlorine

[0082] When the atmosphere in which the mixture is fired is hydrogen chloride gas, the mixture is fired in an atmosphere containing preferably 1% by volume or more, more preferably 10% by volume or more, of hydrogen chloride at a temperature in the range of 600 to 1200°C, preferably 900 to 1100°C, for preferably 10 minutes to 6 hours.

[0083] When the atmosphere in which the mixture is fired is a gas atmosphere containing components prepared from molecular chlorine and water vapor, the mixture is fired in an atmosphere containing preferably 0.5 vol% or more of molecular chlorine and 0.5 vol% or more of water vapor, more preferably 5 vol% or more of molecular chlorine and 5 vol% or more of water vapor, at a temperature in the range of 600 to 1200°C, preferably 900 to 1100°C, for preferably 10 minutes to 6 hours.

[0084] When the atmosphere in which the mixture is fired is a molecular chlorine gas atmosphere, the mixture is fired in an atmosphere containing preferably 0.5% by volume or more, more preferably 5% by volume or more, of molecular chlorine at a temperature in the range of 600 to 1200°C, preferably 900 to 1100°C, for preferably 10 minutes to 6 hours.

[0085] For calcination, any furnace capable of controlling the gas atmosphere, such as an industrially used batch calcination furnace, tunnel furnace, or rotary kiln, can be used. If the resulting particles are large, adding fine magnesium titanate powder to the calcination raw material allows the fine magnesium titanate powder particles to act as seed crystals, thereby reducing the particle size. The larger the amount of fine magnesium titanate powder added, the smaller the particle size becomes.

[0086] The method for mixing the magnesium titanate powder into the barrier rib-forming glass paste is not particularly limited, but the magnesium titanate powder needs to be contained in a uniform and sufficiently dispersed state. Mixing can be carried out by a mixer equipped with high-speed stirring blades, such as a vertical granulator or a Loedige mixer, or by a mixing method using media, such as a ball mill, in a dry system or a wet system with the addition of water or an organic solvent.

[0087] Zinc titanate: The zinc titanate particles of the present invention were obtained as follows. Zinc oxide (ZnO) was used as the main component, and 10 mol % of titanium was added as titanium oxide (TiO2) and 10 mol % of nickel was added as nickel oxide (NiO) and wet-mixed. The resulting mixture was dried, granulated, and then fired at 1200°C to 1500°C. During firing, a zinc titanate (Zn2TiO4) particle layer was formed on the surface of the sintered body. The zinc titanate was removed from this particle layer and pulverized in a jet mill to obtain zinc titanate particles.

[0088] [others] The metal titanate compound particles of the present invention preferably have a coverage of 2% or more on the toner particle surface. When the metal titanate compound coverage of the toner particle surface is 2% or more, the effects of chargeability, image density stability, fluidity, and cleanability are easily exhibited. More preferably, the coverage is 2% or more and 40% or less, from the viewpoint of suppressing component contamination due to detachment of the metal titanate compound from the toner particles.

[0089] The content of the metal titanate compound particles in the toner is preferably 0.1 to 10.0 parts by weight per 100 parts by weight of toner particles. This range of content effectively inhibits toner fusion to the photoreceptor and toner slippage through the cleaning blade, and also provides a toner with excellent chargeability, environmental stability, image density stability, and fogging resistance. A content of 0.2 to 3.0 parts by weight is more preferred.

[0090] The toner particles and the metal titanate compound particles can be mixed using a known mixer such as a Henschel mixer, Mechano Hybrid (manufactured by Nippon Coke Corporation), Super Mixer, or Nobilta (manufactured by Hosokawa Micron Corporation), and the device is not particularly limited.

[0091] <Binder resin> The binder resin used in the toner particles of the present invention can be a common resin, and examples thereof include polyester resin, styrene-acrylic acid copolymer, polyolefin resin, vinyl resin, fluororesin, phenol resin, silicone resin, and epoxy resin. Among these, amorphous polyester resin is used from the viewpoint of improving low-temperature fixability, and it is known to use a low-molecular-weight polyester and a high-molecular-weight polyester in combination from the viewpoint of achieving both low-temperature fixability and hot offset resistance. Furthermore, crystalline polyester may be used as a plasticizer from the viewpoint of further improving low-temperature fixability and blocking resistance during storage.

[0092] <Magnetic iron oxide particles> The toner particles of the present invention may use magnetic iron oxide particles such as those exemplified below. Specific examples include magnetic iron oxide particles such as magnetite, maghemite, and ferrite, as well as magnetic iron oxide particles containing other metal oxides. Conventionally, iron oxides such as iron tetroxide (Fe3O4), iron sesquioxide (γ-Fe2O3), zinc iron oxide (ZnFe2O4), and yttrium iron oxide (Y3Fe5O 12 ), cadmium iron oxide (Cd3Fe2O4), gadolinium iron oxide (Gd3Fe5O 12 ), copper iron oxide (CuFe2O4), lead iron oxide (PbFe 12 O 19 ), nickel iron oxide (NiFe2O4), neodymium iron oxide (NdFe2O3), barium iron oxide (BaFe 12 O 19Known magnetic iron oxide particles include iron oxide magnesium (MgFe2O4), iron oxide manganese (MnFe2O4), iron lanthanum (LaFeO3), and iron powder (Fe). Particularly suitable magnetic iron oxide particles are fine powders of iron tetroxide or gamma ferric oxide. The above-mentioned magnetic iron oxide particles can be used alone or in combination of two or more.

[0093] <Coloring agent> Examples of colorants that can be contained in the toner particles of the present invention include the following: Examples of the colorant include known organic pigments or oil-based dyes, carbon black, and magnetic materials.

[0094] Examples of cyan colorants include copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, and basic dye lake compounds.

[0095] Examples of magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds.

[0096] Examples of yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds.

[0097] Examples of black colorants include carbon black, magnetic materials, and those toned to black using the above-mentioned yellow colorants, magenta colorants, and cyan colorants.

[0098] The colorants can be used alone or in combination of two or more.

[0099] <Release agent> If necessary, the toner particles may contain a release agent that suppresses the occurrence of hot offset during heat fixing of the toner. Typical examples of the release agent include low-molecular-weight polyolefins, silicone wax, fatty acid amides, ester waxes, carnauba wax, hydrocarbon waxes, and Fischer-Tropsch wax.

[0100] <Charge control agent> The toner particles according to the present invention may contain a charge control agent, if necessary. As the charge control agent, a metal compound of an aromatic carboxylic acid is preferred, from the viewpoints of being colorless, having a high charging speed of the toner, and being able to stably maintain a constant charge amount.

[0101] Examples of negative charge control agents include metal salicylate compounds, metal naphthoate compounds, metal dicarboxylic acid compounds, polymeric compounds having sulfonic acid or carboxylic acid on the side chain, polymeric compounds having sulfonate salts or sulfonic acid esters on the side chain, polymeric compounds having carboxylate salts or carboxylic acid esters on the side chain, boron compounds, urea compounds, silicon compounds, and calixarenes.

[0102] The charge control agent may be added internally or externally to the toner particles.

[0103] The content of the charge control agent in the toner particles is preferably 0.01 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the binder resin in the toner particles.

[0104] <Silica fine particles> As the silica microparticles used in the present invention, known silica particles can be used.Specific examples include sol-gel silica particles, aqueous colloidal silica particles, alcoholic silica particles, fumed silica particles obtained by gas phase method, fused silica particles, and deflagration silica particles.Among these, fumed silica particles are preferred in terms of chargeability.

[0105] The silica fine particles are preferably hydrophobized. Examples of hydrophobizing agents include dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diphenyldimethoxysilane, and diphenyldiethoxysilane. Among these, dimethyldimethoxysilane is preferred from the viewpoint of the reactivity of the treating agent.

[0106] Furthermore, it is preferable that the silica particles are treated with dimethyldimethoxysilane and then trimethylsilylated. This allows the small amount of silanol remaining after the dimethyldimethoxysilane treatment to be removed, improving charging stability. Examples of trimethylsilylating agents include trimethylsilanol, trimethylmethoxysilane, trimethylchlorosilane, and hexamethyldisilazane.

[0107] Alternatively, a surface treatment agent containing a siloxane bond may be used. Examples of the surface treatment agent containing a siloxane bond include silicone oils such as dimethyl silicone oil; silicone oils in which the side chain or end of a dimethyl silicone oil is modified with an organic group, such as methylhydrogen silicone oil, methylphenyl silicone oil, alkyl-modified silicone oil, chloroalkyl-modified silicone oil, chlorophenyl-modified silicone oil, fatty acid-modified silicone oil, polyether-modified silicone oil, alkoxy-modified silicone oil, carbinol-modified silicone oil, amino-modified silicone oil, and fluorine-modified silicone oil; and cyclic siloxanes such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane.

[0108] The surface treatment agent containing a siloxane bond is preferably a cyclic siloxane. More preferably, it is a cyclic siloxane having up to 10 ring members. The cyclic siloxane may have a substituent on some of the methyl groups bonded to the silicon atom. Among the cyclic siloxanes, at least one selected from the group consisting of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane is preferred. From the viewpoints of ease of control of the siloxane chain length and ease of purification, it is more preferred to include octamethylcyclotetrasiloxane.

[0109] <Other external additives> In addition to the metal titanate particles and silica fine particles described above, the toner of the present invention may contain other inorganic fine powders as needed. The inorganic fine powders may be added internally to the toner particles or may be mixed with the toner particles as an external additive. As the external additive, inorganic fine powders such as titanium oxide and aluminum oxide are preferred. The inorganic fine powders are preferably hydrophobized with a hydrophobizing agent such as a silane compound, silicone oil, or a mixture thereof.

[0110] As an external additive to improve fluidity, 2 / g or more 400m 2 / g or less, and for stable durability, a specific surface area of ​​10 m 2 / g or more 50m 2 In order to simultaneously improve the flowability and stabilize the durability, inorganic fine powders having a specific surface area within the above range may be used in combination.

[0111] The external additive is preferably used in an amount of 0.1 to 10.0 parts by mass relative to 100 parts by mass of toner particles. The toner particles and the external additive can be mixed using a known mixer such as a Henschel mixer.

[0112] <Career> The toner of the present invention may be mixed with a magnetic carrier and used as a toner for a two-component developer, from the viewpoint of obtaining stable images over a long period of time.

[0113] Examples of magnetic carriers include surface-oxidized iron powder, unoxidized iron powder, metal particles such as iron, lithium, calcium, magnesium, nickel, copper, zinc, cobalt, manganese, and rare earth elements, alloy particles of the above metals, oxide particles of the above metals, magnetic materials such as ferrite, and magnetic material-dispersed resin carriers (so-called resin carriers) containing a magnetic material and a binder resin that holds the magnetic material in a dispersed state.

[0114] [Toner manufacturing method] <Production of toner particles> The toner particles before the metal titanate compound particles are externally added and mixed can be produced by a known melt-kneading and pulverization method. The procedure for producing the toner particles will be described below.

[0115] In the toner particle raw material mixing process, the materials that make up the toner particles, such as binder resin, colorant or pigment dispersion, wax, and, if necessary, charge control agent, are weighed out in predetermined amounts, blended, and mixed. Examples of mixing devices include double cone mixers, V-type mixers, drum mixers, super mixers, Henschel mixers, Nauta mixers, and Mechano Hybrid (manufactured by Nippon Coke and Engineering Co., Ltd.).

[0116] Next, the mixed materials are melt-kneaded to disperse the magnetic material, colorant, etc. into the binder resin. In the melt-kneading process, batch kneaders such as pressure kneaders and Banbury mixers, or continuous kneaders, can be used. Due to their advantage of continuous production, single-screw or twin-screw extruders are the mainstream. Examples include the KTK twin-screw extruder (manufactured by Kobe Steel, Ltd.), the TEM twin-screw extruder (manufactured by Toshiba Machine Co., Ltd.), the PCM kneader (manufactured by Ikegai Corporation), the twin-screw extruder (manufactured by KCK Corporation), the Co-Kneader (manufactured by Buss Co., Ltd.), and the Kneedex (manufactured by Nippon Coke and Engineering Co., Ltd.).

[0117] The kneaded product obtained by melt-kneading may be rolled using a two-roll mill or cooled with water in a cooling step.

[0118] The cooled kneaded product is pulverized to a desired particle size in a pulverization process. In the pulverization process, the product is coarsely pulverized in a pulverizer, and then further pulverized in a fine pulverizer. Examples of pulverizers that perform coarse pulverization include crushers, hammer mills, and feather mills. Examples of fine pulverizers that perform fine pulverization include the Cryptron System (manufactured by Kawasaki Heavy Industries, Ltd.), Super Rotor (manufactured by Nisshin Engineering Inc.), Turbo Mill (manufactured by Turbo Kogyo Co., Ltd.), and fine pulverizers using an air jet system.

[0119] Thereafter, if necessary, the toner particles are classified using a classifier or sieving machine, such as an inertial classification machine such as Elbojet (manufactured by Nittetsu Mining Co., Ltd.), a centrifugal classification machine such as Turboplex (manufactured by Hosokawa Micron Corporation), TSP Separator (manufactured by Hosokawa Micron Corporation), or Faculty (manufactured by Hosokawa Micron Corporation).

[0120] As a means for achieving the density of toner particles within the above range, in addition to a method employing a pulverizing means such as a mechanical pulverizer or a jet pulverizer, any deforming means may be used, such as a Hybridization System (manufactured by Nara Machinery Works, Ltd.), COMPOSI (manufactured by Nippon Coke Co., Ltd.), or a surface modifying machine using hot air, such as Meteor Rainbow (manufactured by Nippon Pneumatic Co., Ltd.) In particular, pulverization using a mechanical pulverizer followed by surface modification using hot air is preferred, as it makes it easier to adjust the density.

[0121] FIG. 1 shows a schematic diagram of a mechanical mill used for fine grinding in the examples described below. When a predetermined amount of coarsely ground material (material to be ground) is fed into the powder supply port (powder inlet) 101 of the mechanical mill, the coarsely ground material is introduced into the grinding chamber, which is the gap between a rotor 103 and a stator 104. The material is then instantaneously ground by impact between the rotor, which rotates at high speed within the grinding chamber and the stator, which also has numerous grooves on its surface. The material is then discharged through a powder outlet 106. Furthermore, as shown in FIG. 1, the mechanical mill preferably includes a swirl chamber 102 connected to the supply port 101. The coarsely ground material entering through the supply port 101 swirls along the wall of the swirl chamber 102. As it continues to swirl, the coarsely ground material is introduced into the grinding chamber according to its particle size. This means that the flow is more rectified than in a mill without a swirl chamber, making it easier for the material to enter the desired location according to its particle size.

[0122] 2 shows an outline of a fine grinding system incorporating another jet mill used in the examples described below. In this fine grinding system, coarsely ground material is introduced into a raw material feeder 233, and then from the raw material feeder 233, it is introduced into an air classifier 232 via a conveying pipe 234. The air classifier 232 has a center core 240 and a separate core 241 in a collector 238. In the air classifier 232, the coarsely ground material is classified into finely ground material and coarse particles by secondary air introduced from a secondary air supply port 243. The classified finely ground material is discharged outside the system via a discharge pipe 242. The classified coarse particles are introduced into the jet mill fine grinder 231 via a main body hopper section 239. In the fine grinding mill, coarse particles are supplied to a nozzle 235 through which compressed air is introduced, and the coarse particles are transported by the high-speed compressed air and collide with a collision plate 236 in a grinding chamber 237 to be finely ground. The finely ground coarse particles are then introduced into a wind classifier 232 via a conveying pipe 234 and classified again.

[0123] Next, the heat treatment of the toner particles obtained through the pulverizing means using the heat treatment device using hot air shown in FIG. 3 will be described.

[0124] The toner particles supplied by the material supply means 301 are introduced into an introduction pipe 303, which is installed vertically to the material supply means, by compressed gas adjusted by a compressed gas adjustment means 302. The toner particles passing through the introduction pipe are uniformly dispersed by a conical protruding member 304 installed in the center of the material supply means, and are introduced into eight supply pipes 5 that radiate outward, and are then introduced into a treatment chamber 306 where heat treatment is carried out.

[0125] At this time, the flow of the toner particles supplied to the processing chamber is regulated by a regulating means 309 for regulating the flow of toner particles provided in the processing chamber, so that the toner particles supplied to the processing chamber are heat-treated while swirling in the processing chamber, and then cooled.

[0126] Heat for heat-treating the supplied toner particles is supplied from hot air supply means 307, distributed by distribution member 312, and introduced into the processing chamber by swirling member 313, which swirls the hot air in a spiral. The swirling member 313 for swirling the hot air has multiple blades, and the swirling of the hot air can be controlled by adjusting the number and angle of the blades. The hot air supplied into the processing chamber preferably has a temperature of 100°C to 300°C at the outlet of hot air supply means 307, and more preferably 130°C to 170°C. If the temperature at the outlet of the hot air supply means is within the above range, it is possible to uniformly adjust the density of the toner particles while preventing them from fusing or coalescing due to excessive heating. The hot air is supplied from hot air supply means outlet 311.

[0127] The heat-treated particles are then cooled by cold air supplied from the cold air supply means 308. The temperature of the cold air supplied from the cold air supply means 308 is preferably -20°C to +30°C. If the temperature of the cold air is within the above range, the heat-treated particles can be efficiently cooled, and fusion and excessive coalescence of the particles can be prevented without hindering the adjustment of a uniform density of the toner particles. The absolute moisture content of the cold air is 0.5 g / m 3 More than 15.0g / m 3 It is preferable that:

[0128] The toner particles and inorganic fine particles may be mixed in advance to prepare toner particles carrying inorganic fine particles, and then the heat treatment may be carried out.

[0129] Next, the cooled, heat-treated toner particles are collected by the collection means 310 at the bottom end of the processing chamber. A blower (not shown) is provided ahead of the collection means, and the toner particles are sucked and transported by the blower.

[0130] The powder particle supply port 314 is positioned so that the swirling direction of the supplied toner particles and the swirling direction of the hot air are the same, and the surface treatment device recovery means 310 is positioned on the outer periphery of the treatment chamber to maintain the swirling direction of the swirled powder particles. Furthermore, the cold air supplied from the cold air supply means 308 is configured to be supplied horizontally and tangentially from the outer periphery of the device to the circumferential surface of the treatment chamber. The swirling directions of the toner particles supplied from the powder supply port, the cold air supplied from the cold air supply means, and the hot air supplied from the hot air supply means are all the same. This prevents turbulence within the treatment chamber, strengthens the swirling flow within the device, applies a strong centrifugal force to the toner particles, and further improves dispersibility, resulting in heat-treated toner particles with fewer coalescence particles and uniform shapes.

[0131] <Toner manufacturing (mixing process of toner particles and external additives)> The toner is obtained by mixing (externally adding) the above-mentioned metal titanate compound particles and, if necessary, other external additives with the toner particles. The mixing can be performed using a mixer having a rotor with an agitating member (agitating blade) and a main casing (a mixing tank) provided with a gap between the agitating member and the rotor.

[0132] Examples of mixing devices include a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.), a Super Mixer (manufactured by Kawata Co., Ltd.), a Ribocone (manufactured by Okawara Manufacturing Co., Ltd.), a Nauta mixer, a Turbulizer, a Cyclomix, a Nobilta (manufactured by Hosokawa Micron Corporation), a Spiral Pin Mixer (manufactured by Pacific Machinery Works Co., Ltd.), and a Loedige Mixer (manufactured by Matsubo Co., Ltd.). In particular, a Henschel mixer (manufactured by Mitsui Mining Co., Ltd.) is suitable for uniformly mixing the external additive and the toner particles and for breaking up aggregates of the external additive.

[0133] The operation of the mixer is as follows.

[0134] The peripheral speed of the tip of the stirring blade of the mixer is set within a predetermined range as described above.

[0135] Next, the top cover of the processing chamber of the mixing device is opened, and the material to be processed containing the pre-measured toner particles and external additives is put in. After the material is put in, the top cover is closed, and the stirring blade is rotated at the tip peripheral speed described above.

[0136] Furthermore, while the stirring blades are rotating, cold water is supplied from the cold water generating means to the water cooling jacket, thereby adjusting the temperature inside the processing chamber to a temperature equal to or lower than the glass transition point (Tg) of the resin component contained in the toner particles.

[0137] After processing for a certain mixing time, the discharge valve is opened and the toner is discharged from the processing chamber. If necessary, it is then passed through a mesh with openings of 35 μm to 75 μm to remove coarse particles and obtain the toner.

[0138] The mixing time is preferably adjusted so that the temperature of the materials during processing is equal to or lower than the glass transition temperature (Tg) of the resin component contained in the toner particles. Specifically, the mixing time is preferably adjusted within a range of 0.5 minutes to 60 minutes.

[0139] [Methods for measuring various physical properties] The methods for measuring various physical properties of the toner and raw materials are described below.

[0140] <Measuring methods for volume average particle size (Dv), weight average particle size (D4), and number average particle size (D1)> The volume average particle diameter (Dv) (weight average particle diameter (D4)) and number average particle diameter (D1) of the toner are calculated as follows. The measurement device used is a particle counting and analysis device "CDA-1000X" (manufactured by Sysmex Corporation) that uses the pore electrical resistance method and is equipped with a 100 μm aperture tube. The measurement conditions are set and the measurement data is analyzed using the accompanying dedicated software "CDA-1000X" (manufactured by Sysmex Corporation).

[0141] The aqueous electrolyte solution used for the measurement may be, for example, "Cell Pack" (manufactured by Sysmex Corporation).

[0142] Before carrying out the measurements and analysis, the dedicated software was set up as follows.

[0143] On the "measurement condition setting" screen of the dedicated software, set the total count number to 50,000, the number of repeated measurements to 1, and the measurement mode to total count (no limit).

[0144] The specific measurement method is as follows. (1) Pour approximately 150 ml of the electrolyte solution into a dedicated glass round-bottom beaker, set it on the sample stage, and stir with the stirring propeller at 500 rpm. Then, click "Blank Check Measurement" in the dedicated software to start the measurement and confirm that the count is less than 500. If the count is 500 or more, repeatedly clean the beaker and aperture. (2) Approximately 30 ml of the above-mentioned aqueous electrolyte solution is placed in a 100 ml flat-bottom glass beaker, and approximately 0.3 ml of a dilution of Contaminon N (a 10% aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) diluted approximately three times by mass with ion-exchanged water is added as a dispersant. (3) Prepare an ultrasonic disperser "Ultrasonic Dispension System Tetra150" (manufactured by Nikkaki Bios Co., Ltd.) with an electrical output of 120 W and two built-in oscillators with an oscillation frequency of 50 kHz and a phase difference of 180 degrees. Place approximately 3.3 L of ion-exchanged water in the ultrasonic disperser's water tank and add approximately 2 mL of Contaminon N to this water tank. (4) Set the beaker (2) in the beaker fixing hole of the ultrasonic disperser, operate the ultrasonic disperser, and adjust the height of the beaker so that the resonance state of the liquid surface of the electrolytic solution in the beaker is maximized. (5) While ultrasonic waves are being applied to the electrolyte solution in the beaker from (4), approximately 10 mg of toner is added little by little and dispersed. The ultrasonic dispersion process is then continued for another 60 seconds. During the ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted to be between 10°C and 40°C. (6) Using a pipette, add the electrolyte solution (5) containing the dispersed toner to the round-bottom beaker (1) placed in the sample stand, and adjust the measurement concentration to approximately 6%. Then, measure the particle count until it reaches 50,000 particles. (7) The measurement data is analyzed using the dedicated software provided with the device to calculate the volume average particle size (Dv) (weight average particle size (D4)) and number average particle size (D1).

[0145] <Method for measuring the number average particle size of inorganic fine particles> The number-average particle size of inorganic particles is calculated from images of inorganic particles separated from toner (or a mixture with pigment if the toner particles contain pigment) taken with a Hitachi ultra-high resolution field emission scanning electron microscope S-4800 (Hitachi High-Technologies Corporation). The image taking conditions for the S-4800 are as follows:

[0146] (1) Sample preparation A thin layer of conductive paste is applied to a sample stage (aluminum sample stage 15 mm x 6 mm), and the inorganic particles separated from the toner are sprayed onto it. An air blow is then used to remove excess inorganic particles from the sample stage, and the stage is allowed to dry thoroughly. The sample stage is then placed in the sample holder, and the sample stage height is adjusted to 36 mm using the sample height gauge.

[0147] (2) S-4800 observation condition setting The number average particle diameter is calculated using images obtained by backscattered electron image observation using the S-4800. Liquid nitrogen is poured into the anti-contamination trap attached to the S-4800 housing until it overflows, and then left for 30 minutes. Start the S-4800's "PC-SEM" and perform flushing (cleaning the FE chip, which is the electron source). Click the accelerating voltage display area on the control panel on the screen and press the [Flushing] button to open the flushing execution dialog. Confirm that the flushing intensity is 2 and execute it. Confirm that the emission current due to flushing is 20-40 μA. Insert the sample holder into the sample chamber of the S-4800 housing. Press [Origin] on the control panel to move the sample holder to the observation position.

[0148] Click the accelerating voltage display to open the HV setting dialog, and set the accelerating voltage to [1.1 kV] and the emission current to [20 μA]. In the [Basic] tab of the operation panel, set the signal selection to [SE], select [Upper (U)] and [+BSE] for the SE detector, and select [LA100] in the selection box to the right of [+BSE] to set the mode for observation using backscattered electron images. Also in the [Basic] tab of the operation panel, set the probe current in the electron optical system condition block to [Normal], the focus mode to [UHR], and the WD to [4.5 mm]. Press the [ON] button in the accelerating voltage display on the control panel to apply the accelerating voltage.

[0149] (3) Focus adjustment Rotate the focus knob [COARSE] on the control panel until the image is in focus to some extent, then adjust the aperture alignment. Click [Align] on the control panel to display the alignment dialog and select [Beam]. Rotate the STIGMA / ALIGNMENT knobs (X, Y) on the control panel to move the displayed beam to the center of the concentric circles. Next, select [Aperture] and rotate the STIGMA / ALIGNMENT knobs (X, Y) one by one to stop the image movement or minimize its movement. Close the aperture dialog and use autofocus to adjust the focus. Then, set the magnification to 80,000 (80k)x and adjust the focus using the focus knob and STIGMA / ALIGNMENT knob as described above, then use autofocus to adjust the focus again. Repeat this process to adjust the focus. Here, if the inclination angle of the observation surface is large, the measurement accuracy of the number average particle diameter tends to be low. Therefore, when adjusting the focus, select an object that can simultaneously bring the entire observation surface into focus, and select an object with as little surface inclination as possible for analysis.

[0150] (4) Save image Adjust the brightness in ABC mode, take a photo at a size of 640 x 480 pixels, and save it. This image file will be used for the following analysis. To measure the particle size of at least 500 inorganic microparticles and calculate the number-average particle size, take images at multiple locations so as to avoid photographing the same inorganic microparticles, and obtain the required number of particles.

[0151] (5) Image analysis The particle diameters of at least 500 inorganic fine particles are measured to determine the number-average particle diameter. In the present invention, the number-average particle diameter is calculated by binarizing the image obtained by the above-mentioned method using image analysis software Image-Pro Plus ver. 5.0.

[0152] If the inorganic fine particles separated from the toner contain pigments or other contaminants, they are first subjected to elemental analysis using an energy dispersive X-ray analyzer (EDS) and discrimination based on particle size and shape, and measurements are then carried out after excluding particles other than the inorganic fine particles to be measured.

[0153] <Method for measuring density> The density of the toner particles is measured using a flow particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation) under the measurement and analysis conditions at the time of calibration work.

[0154] The specific measurement method is as follows. First, approximately 20 ml of ion-exchanged water, from which impurities such as solids have been removed, is placed in a glass container. Approximately 0.2 ml of a solution prepared by diluting "Contaminon N" (a 10% by weight aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) approximately three times by weight with ion-exchanged water is added. Approximately 0.02 g of the measurement sample is then added, and the mixture is dispersed for two minutes using an ultrasonic disperser to obtain a dispersion for measurement. The dispersion is then cooled appropriately so that its temperature is between 10°C and 40°C. A tabletop ultrasonic cleaner disperser with an oscillation frequency of 50 kHz and an electrical output of 150 W (e.g., "VS-150" manufactured by Vervoclear) is used as the ultrasonic disperser. A predetermined amount of ion-exchanged water is placed in the water tank, and approximately 2 ml of the Contaminon N is added to the water tank.

[0155] For the measurements, the flow particle image analyzer described above was equipped with an "UPlanApro" objective lens (10x magnification, 0.40 numerical aperture), and a particle sheath "PSE-900A" (manufactured by Sysmex Corporation) was used as the sheath liquid. The dispersion prepared according to the procedure described above was introduced into the flow particle image analyzer, and 3,000 toner particles were measured in HPF measurement mode and total count mode. The binary threshold for particle analysis was set to 85%, and the analyzed particle diameter was limited to a circle-equivalent diameter of 1.985 μm or more and less than 39.69 μm, and the toner particle density was determined.

[0156] Before starting the measurement, automatic focus adjustment is performed using standard latex particles (for example, Duke Scientific's "RESEARCH AND TEST PARTICLES Latex Microsphere Suspensions 5200A" diluted with ion-exchanged water). After that, it is preferable to perform focus adjustment every two hours from the start of the measurement.

[0157] In the examples of the present application, a flow-type particle image analyzer was used that had been calibrated by Sysmex Corporation and had a calibration certificate issued by Sysmex Corporation. Measurements were carried out under the same measurement and analysis conditions as when the calibration certificate was received, except that the particle diameters to be analyzed were limited to equivalent-circle diameters of 1.985 μm or more and less than 39.69 μm.

[0158] The measurement principle of the flow-type particle image analyzer "FPIA-3000" (Sysmex Corporation) is to capture still images of flowing particles and perform image analysis. A sample is added to the sample chamber and delivered to the flat sheath flow cell using a sample suction syringe. The sample is sandwiched between sheath fluid and forms a flat flow. A strobe light is irradiated onto the sample passing through the flat sheath flow cell at 1 / 60-second intervals, allowing for still images of the flowing particles. Furthermore, because the flow is flat, the images are captured in focus. Particle images are captured by a CCD camera, and the captured images are processed at a 512 x 512 resolution (0.37 x 0.37 μm per pixel). The contours of each particle image are extracted, and the perimeter and projected area of ​​the particle image, as well as the length and area of ​​the envelope of the toner particle's projected image, are measured.

[0159] Next, the density is calculated using the projected area and envelope area of ​​the toner particle image by the following formula: Density = (projected area of ​​toner particle) / (area of ​​toner particle projected image surrounded by envelope)

[0160] Density is a quantity that takes a value between 0 and 1, and the smaller the value, the more recesses there are and the more complex the shape.

[0161] <Method for measuring shear adhesion> The shear adhesive strength was measured using a "Ring Shear Tester RST-XS.s" (manufactured by Dr.-ing. Dietmar Schulze).

[0162] Specifically, measurements were performed at room temperature (23°C, 60% RH) using a rotating cell (cylindrical, inner diameter 32 mm, outer diameter 64 mm, volume 9.65 ml) capable of applying linear shear force in the cross-sectional direction. A metal titanate compound was placed in the cell, and a vertical load of 4.0 kPa was applied. A compacted powder layer was created to achieve the densest packing at this vertical load. Measurements using a ring shear tester are advantageous because they automatically detect the pressure at which this compaction occurs and can be created without individual variation. Similarly, compacted powder layers were created at vertical loads of 8.0 kPa, 12.0 kPa, and 16.0 kPa. The samples formed at each vertical load were then subjected to a gradual shear force while continuing to apply the vertical load applied when the compacted powder layer was formed. The fluctuations in shear stress during this process were measured, and the steady-state point was determined.

[0163] The steady state is judged to have been reached when, in the above test, the displacement of the shear stress and the vertical displacement of the load application means for applying the vertical load become small and both take stable values.

[0164] Next, the normal load is gradually removed from the consolidated powder layer that has reached a steady state, and a failure envelope (plot of normal load stress vs. shear stress) is created at each load, and the Y-intercept and slope are calculated. In analysis using the Mohr-Coulomb model, the failure envelope is expressed by the following formula, where the Y-intercept is the "shear adhesion force" and the slope is the "internal friction angle."

[0165]

number

[0166] [Configurations included in the embodiments of the present invention] The disclosure of this embodiment includes the following configuration. (Configuration 1) A method for producing a toner, comprising a mixing step of stirring and mixing toner particles containing a binder resin and a colorant with a material containing metal titanate compound particles, the toner particles have a density of 0.90 or more and 0.99 or less; the metal titanate compound particles have a shear adhesive strength of 4000 Pa or more and 10000 Pa or less, The toner manufacturing method is characterized in that the mixing step is a step of stirring and mixing the material to be treated by using a mixing device having a mixing tank and a rotatable stirring blade provided in the mixing tank, and rotating the stirring blade in the mixing tank at a tip peripheral speed of 30 m / s or more and 70 m / s or less. (Configuration 2) The method for producing a toner according to Configuration 1, wherein the metal titanate compound particles are selected from the group consisting of strontium titanate particles, calcium titanate particles, magnesium titanate particles, and zinc titanate particles. (Configuration 3) The method for producing a toner according to Configuration 1 or 2, wherein the metal titanate compound particles are treated with a silane coupling agent. (Configuration 4) The method for producing a toner according to Configuration 1 or 2, wherein the metal titanate compound particles are treated with silicone oil. (Configuration 5) The method for producing a toner according to Configuration 1 or 2, wherein the metal titanate compound particles are treated with a silane coupling agent and silicone oil. (Configuration 6) The method for producing a toner according to Configuration 3 or 5, wherein the silane coupling agent is an alkyltrialkoxysilane having an alkyl group having 3 to 6 carbon atoms. (Configuration 7) The method for producing a toner according to any one of Configurations 1 to 6, wherein the metal titanate compound particles have a number average particle diameter of 10 nm or more and 500 nm or less. (Configuration 8) The method for producing a toner according to any one of Configurations 1 to 7, wherein the toner contains silica fine particles having a number average particle diameter of 50 nm or more and 200 nm or less. [Example]

[0167] The present invention will be described below with reference to Production Examples and Examples. In the following description, the number of parts is based on parts by mass.

[0168] <Production Example of Metal Titanate Compound Particles 1> Metatitanic acid produced by the sulfuric acid method was deironized and bleached, then desulfurized by adding a 3N aqueous solution of sodium hydroxide to adjust the pH to 9.0, and then neutralized to pH 5.6 with 5N hydrochloric acid, filtered, and washed with water. Water was added to the washed cake to make a slurry of 1.90 mol / L in terms of TiO2, and hydrochloric acid was added to adjust the pH to 1.4, which was then subjected to peptization.

[0169] After desulfurization and peptization, 1.90 moles of metatitanic acid (TiO2) was collected and placed in a 3-L reaction vessel. To the peptized metatitanic acid slurry, 2.185 moles of strontium chloride aqueous solution was added to achieve a SrO / TiO2 molar ratio of 1.15, and the TiO2 concentration was adjusted to 1.039 moles / L. The mixture was then heated to 90°C with stirring, and 440 mL of 10N sodium hydroxide aqueous solution was added over 40 minutes. Stirring was continued at 95°C for 30 minutes, after which the mixture was poured into ice water and rapidly cooled to terminate the reaction.

[0170] The reaction slurry was heated to 70°C, 12N hydrochloric acid was added until the pH reached 5.0, and stirring was continued for 1 hour. The resulting precipitate was decanted. The slurry containing the resulting precipitate was adjusted to 40°C, and hydrochloric acid was added to adjust the pH to 2.5. 10 parts of isobutyltrimethoxysilane was then added per 100 parts of solids, and the mixture was stirred for 10 hours. The viscosity was then 0.015 m. 2 Three parts of dimethyl silicone oil (100 parts solids) was added and stirred for 10 hours. A 5N aqueous solution of sodium hydroxide was added to adjust the pH to 6.5, and stirring was continued for one hour. After filtration and washing, the resulting cake was dried in air at 120°C for eight hours to obtain strontium titanate. The shear adhesive strength of the resulting strontium titanate was 6000 Pa. Its physical properties are shown in Table 1.

[0171] <Production Examples of Metal Titanate Compound Particles 2 to 28 and 31> Metal titanate compound particles 2 to 28 and 31 were obtained in the same manner as in Production Example 1 of metal titanate compound particles 1, except that the particle size of the metal titanate compound, the type and amount of the silane coupling treatment agent, and the viscosity and amount of the silicone oil treatment agent were changed as shown in Table 1. Their physical properties are shown in Table 1.

[0172] <Production Example of Metal Titanate Compound Particles 29> Metatitanic acid obtained by the sulfuric acid method was deironized and bleached, then adjusted to pH 9.0 with aqueous sodium hydroxide, and desulfurized. It was then neutralized to pH 5.8 with hydrochloric acid, filtered, and washed to obtain a washed cake of metatitanic acid with a SO content of 9.3 g / kg. Water was added to the washed cake to form a slurry with a Ti content of 2.13 mol / L, and hydrochloric acid was added to adjust the pH to 1.4, followed by peptization. 0.764 mol of the peptized metatitanic acid (TiO2) was collected and placed in a reaction vessel. Calcium hydroxide was added to the mixture to achieve a Ca / Ti molar ratio of 1.15, followed by 0.044 mol of glucose, followed by 0.9 mol of sodium hydroxide. Water was added to bring the total volume to 0.6 L, and the resulting mixture was stirred for 30 minutes.

[0173] The mixed solution was further heated to 150°C while stirring, and stirring was continued for 10 hours to complete the reaction. The reaction-completed slurry was cooled to 50°C, and hydrochloric acid was added until the pH reached 5.0, followed by stirring for another hour. The resulting precipitate was decanted and separated by filtration, and then dried in air at 120°C for 10 hours to obtain calcium titanate. The shear adhesion strength of the resulting calcium titanate was 9520 Pa. The physical properties are shown in Table 1.

[0174] <Production Example of Metal Titanate Compound Particles 30> Metatitanic acid produced by the sulfuric acid method was deironized and bleached, then desulfurized by adding a 3N aqueous solution of sodium hydroxide to adjust the pH to 9.0, and then neutralized to pH 5.6 with 5N hydrochloric acid, filtered, and washed with water. Water was added to the washed cake to make a slurry of 1.90 mol / L in terms of TiO2, and hydrochloric acid was added to adjust the pH to 1.4, which was then subjected to peptization.

[0175] After desulfurization and peptization, 1.90 moles of metatitanic acid (TiO2) was collected and placed in a 3-L reaction vessel. To the peptized metatitanic acid slurry, 2.185 moles of barium chloride aqueous solution were added to achieve a BaO / TiO2 molar ratio of 1.15, and the TiO2 concentration was adjusted to 1.039 moles / L. The mixture was then heated to 90°C with stirring, and 440 mL of 10N sodium hydroxide aqueous solution was added over 40 minutes. Stirring was continued for 30 minutes at 95°C, after which the mixture was poured into ice water and rapidly cooled to terminate the reaction.

[0176] The reaction slurry was heated to 70°C, and 12N hydrochloric acid was added until the pH reached 5.0. Stirring was continued for 1 hour, and the resulting precipitate was decanted. After filtration and washing, the resulting cake was dried in the air at 120°C for 8 hours to obtain barium titanate. The shear adhesion strength of the obtained barium titanate was 9860 Pa. The physical properties are shown in Table 1.

[0177] <Production Example of Metal Titanate Compound Particles 32> Metal titanate compound particles 32 were obtained in the same manner as in the production example of metal titanate compound particles 30, except that the particle diameter of the metal titanate compound was changed as shown in Table 1. The physical properties are shown in Table 1.

[0178] [Table 1]

[0179] <Production example of binder resin L> Polyoxypropylene(2.2)-2,2-bis(4-hydroxyphenyl)propane: 72.0 parts (0.20 moles; 100.0 mole% based on the total number of moles of polyhydric alcohol) Terephthalic acid: 28.0 parts (0.17 moles; 100.0 mole % based on the total number of moles of polycarboxylic acids) 0.5 parts tin 2-ethylhexanoate (esterification catalyst) The above materials were weighed and placed in a reaction vessel equipped with a condenser, a stirrer, a nitrogen inlet tube, and a thermocouple. After the atmosphere in the flask was replaced with nitrogen gas, the temperature was gradually raised with stirring, and the mixture was allowed to react at 200°C for 4 hours with stirring.

[0180] The pressure inside the reactor was then reduced to 8.3 kPa and maintained at this temperature for 1 hour, after which the reactor was cooled to 180°C and returned to atmospheric pressure.

[0181] Trimellitic anhydride: 3 parts (0.01 mole; 4.0 mole% based on the total number of moles of polycarboxylic acids) tert-butylcatechol (polymerization inhibitor): 0.1 parts Thereafter, the above materials were added, the pressure in the reaction vessel was reduced to 8.3 kPa, and the reaction was carried out for 1 hour while maintaining the temperature at 180°C. After confirming that the softening point measured in accordance with ASTM D36-86 reached 90°C, the temperature was reduced to stop the reaction, and binder resin L was obtained.

[0182] <Production example of binder resin H> Polyoxypropylene(2.2)-2,2-bis(4-hydroxyphenyl)propane: 72.3 parts (0.20 moles; 100.0 mole% based on the total number of moles of polyhydric alcohol) Terephthalic acid: 18.3 parts (0.11 mole; 65.0 mol% based on the total number of moles of polycarboxylic acids) Fumaric acid: 2.9 parts (0.03 moles; 15.0 mole% based on the total number of moles of polycarboxylic acids) 0.5 parts tin 2-ethylhexanoate (esterification catalyst) The above materials were weighed and placed in a reaction vessel equipped with a condenser, a stirrer, a nitrogen inlet tube, and a thermocouple. After the atmosphere in the flask was replaced with nitrogen gas, the temperature was gradually raised with stirring, and the mixture was allowed to react at 200°C for 2 hours with stirring.

[0183] The pressure inside the reactor was then reduced to 8.3 kPa and maintained for 1 hour, after which the reactor was cooled to 180 and returned to atmospheric pressure.

[0184] Trimellitic anhydride: 6.5 parts (0.03 moles; 20.0 mole% based on the total number of moles of polycarboxylic acids) tert-butylcatechol (polymerization inhibitor): 0.1 parts Thereafter, the above materials were added, the pressure in the reaction vessel was reduced to 8.3 kPa, and the reaction was carried out for 15 hours while maintaining the temperature at 160°C. After it was confirmed that the softening point measured in accordance with ASTM D36-86 had reached 137°C, the temperature was reduced to stop the reaction, and binder resin H was obtained.

[0185] <Silica Microparticle Production Example 1> 500 g of fumed silica (silica fine particle substrate) having a number average particle size of 100 nm was placed in a reaction vessel, and the mixture was heated and stirred under a nitrogen purge, while the temperature inside the reaction vessel was controlled to 330°C.

[0186] Next, hexamethyldisilazane vapor was supplied as a surface treatment agent into the reaction vessel at 8 g / min for 60 minutes. The mixture was then heated and stirred for 120 minutes to perform surface treatment on the silica microparticle substrate. The reaction vessel was then purged with nitrogen to remove any unreacted surface treatment agent, yielding silica microparticles 1. The physical properties of the resulting silica microparticles 1 are shown in Table 2.

[0187] <Production Examples of Silica Microparticles 2 to 5> The fumed silica was produced in the same manner as for silica fine particles 1, except that the number average particle diameter was changed as shown in Table 2. The physical properties of the obtained silica fine particles 2 to 5 are shown in Table 2.

[0188] [Table 2]

[0189] <Production Example of Toner Particle 1> 70 parts of binder resin L Binding resin H 30 parts Fischer-Tropsch wax (hydrocarbon wax, maximum endothermic peak temperature 90°C) 5 parts CI Pigment Blue 15:3 5 parts The raw materials shown in the recipe above were mixed in a Henschel mixer (FM75J type, manufactured by Mitsui Miike Chemical Engineering Co., Ltd.) at a rotation speed of 20 s -1 After mixing for 5 minutes, the mixture was kneaded in a twin-screw kneader (PCM-30, manufactured by Ikegai Corporation) set at a temperature of 130°C and a barrel rotation speed of 200 rpm. The kneaded mixture was cooled and coarsely pulverized to 1 mm or less using a hammer mill to obtain a coarsely pulverized product.

[0190] The obtained coarsely crushed material was finely crushed in a mechanical crusher (T-250, manufactured by Turbo Kogyo Co., Ltd.) shown in FIG. 1. The operating conditions of the mechanical crusher were a feed of 10 kg / h and a rotation speed of 11,000 rpm. Further, classification was carried out using a rotary classifier (200TSP, manufactured by Hosokawa Micron Corporation), and toner particles 1 having a weight average particle size (D4) of 6.5 μm were obtained. The operating conditions of the rotary classifier (200TSP, manufactured by Hosokawa Micron Corporation) were a classification rotor rotation speed of 50.0 s -1 It was decided.

[0191] 5.0 parts of silica fine particles having a number-average particle diameter of 10 nm were added to 100 parts of the obtained toner particles, and the mixture was mixed in a Henschel mixer (FM-75 model, manufactured by Nippon Coke & Engineering Co., Ltd., mixing vessel capacity 75 liters) at a rotation speed of 30 s -1 The mixture was mixed for a rotation time of 10 minutes to obtain toner particles 1 before heat treatment.

[0192] The obtained pre-heat-treated toner particles were subjected to heat treatment using the surface treatment device shown in FIG. 3 to obtain heat-treated toner particles 1. The operating conditions were a feed rate of 5 kg / hr, a hot air temperature of 240° C., and a hot air flow rate of 6 m 3 / min., cold air temperature E=5℃, cold air flow rate=4m 3 / min., cold air absolute moisture content = 3g / m 3 , Blower air volume = 20m 3 / min., injection air flow rate = 1m 3 The density of the obtained heat-treated toner particles 1 was 0.94. The physical properties are shown in Table 3.

[0193] <Production Example of Toner Particle 2> Toner particles 2 were obtained by carrying out the same production procedure as in the production example of toner particles 1, except that the step of adding silica fine particles before the heat treatment was omitted.

[0194] <Production Examples of Toner Particles 3 to 5> Toner particles 3 to 5 were obtained by the same production procedure as in the production example of toner particle 2, except that the feed of the pulverizer and the hot air temperature of the heat treatment device were changed as shown in Table 3. Toner particle 5 was not subjected to heat treatment. The physical properties are shown in Table 3.

[0195] <Production Example of Toner Particle 6> In the production example of toner particles 2, pulverization was carried out using a jet pulverization device as shown in Figure 2 instead of the mechanical pulverizer. The operating conditions for the jet pulverizer were a feed of 10 kg / h. No heat treatment was carried out. The density of the obtained toner particles was 0.90. The physical properties are shown in Table 3.

[0196] <Production Example of Toner Particle 7> Toner particles 6 were obtained by the same production procedure as in the production example of toner particles 6, except that the feed of the pulverizer was changed as shown in Table 3. The resulting toner particles had a density of 0.89. The physical properties are shown in Table 3.

[0197] [Table 3]

[0198] <Toner 1 manufacturing example> 100 parts of toner particles 0.5 parts of metal titanate compound particles Silica particles 1 0.5 parts A Henschel mixer (FM-75 model, manufactured by Nippon Coke & Engineering Co., Ltd., mixing vessel capacity 75 liters) was prepared as a mixing device, and a Y1 blade was used as its stirring blade. The materials specified in the recipe were placed in the Henschel mixer, with cooling water at approximately 10°C flowing through the mixer jacket, and mixed at a stirring blade tip peripheral speed of 50 m / s for 10 minutes. The mixture was then sieved through a mesh with 150 μm openings to obtain Toner 1. The composition of Toner 1 is shown in Table 4.

[0199] <Production examples of toners 2 to 46> In the production example of Toner 1, production was carried out in the same manner as Toner 1, except that the toner particles, metal titanate compound particles, silica fine particles, and the peripheral speed of the tip of the stirring blade were changed as shown in Table 4. The compositions of Toners 2 to 46 are shown in Table 4.

[0200] [Table 4]

[0201] <Production example of magnetic core particle 1> Process 1 (weighing and mixing process): Fe2O362.7 parts MnCO329.5 parts Mg(OH)26.8 parts SrCO31.0 parts The ferrite raw materials were weighed so as to achieve the above composition ratio, and then pulverized and mixed for 5 hours in a dry vibration mill using stainless steel beads with a diameter of 1 / 8 inch.

[0202] Step 2 (pre-baking): The resulting pulverized material was made into pellets of approximately 1 mm square using a roller compactor. The pellets were passed through a vibrating sieve with 3 mm openings to remove coarse particles, and then through a vibrating sieve with 0.5 mm openings to remove fine particles. The pellets were then fired in a burner-type firing furnace at 1000°C for 4 hours in a nitrogen atmosphere (oxygen concentration 0.01% by volume) to produce calcined ferrite. The composition of the resulting calcined ferrite was as follows: (MnO)a(MgO)b(SrO)c(Fe2O3)d In the above formula, a=0.257, b=0.117, c=0.007, d=0.393

[0203] Step 3 (Crushing): After crushing the material to about 0.3 mm using a crusher, 30 parts of water were added to 100 parts of the calcined ferrite and crushed in a wet ball mill using zirconia beads with a diameter of 1 / 8 inch for 1 hour. The resulting slurry was crushed in a wet ball mill using alumina beads with a diameter of 1 / 16 inch for 4 hours to obtain a ferrite slurry (finely crushed calcined ferrite).

[0204] ·Process 4 (granulation process): To the ferrite slurry, 1.0 part of ammonium polycarboxylate as a dispersant and 2.0 parts of polyvinyl alcohol as a binder were added per 100 parts of calcined ferrite, and the mixture was granulated into spherical particles using a spray dryer (manufacturer: Okawahara Kakoki Co., Ltd.). After adjusting the particle size of the resulting particles, they were heated in a rotary kiln at 650°C for 2 hours to remove the organic components of the dispersant and binder.

[0205] Step 5 (firing): To control the firing atmosphere, the material was heated from room temperature to 1300°C in a nitrogen atmosphere (oxygen concentration 1.00% by volume) in an electric furnace over two hours, and then fired at 1150°C for four hours. The material was then cooled to 60°C over four hours, returned from the nitrogen atmosphere to the air, and removed at a temperature of 40°C or below.

[0206] Step 6 (sorting): After crushing the agglomerated particles, low magnetic particles were removed by magnetic separation, and coarse particles were removed by sieving through a sieve with a mesh size of 250 μm to obtain magnetic core particles 1 with a volume distribution-based 50% particle size (D50) of 37.0 μm.

[0207] <Preparation of Coating Resin 1> Cyclohexyl methacrylate monomer 26.8% by mass Methyl methacrylate monomer 0.2% by mass Methyl methacrylate macromonomer 8.4% by mass (a macromonomer with a weight-average molecular weight of 5000 and a methacryloyl group at one end) Toluene 31.3% by mass Methyl ethyl ketone 31.3% by mass Azobisisobutyronitrile 2.0% by mass Of the above materials, cyclohexyl methacrylate monomer, methyl methacrylate monomer, methyl methacrylate macromonomer, toluene, and methyl ethyl ketone were placed in a four-neck separable flask equipped with a reflux condenser, thermometer, nitrogen inlet tube, and stirrer, and nitrogen gas was introduced to replace the atmosphere inside the system. The mixture was then heated to 80°C, azobisisobutyronitrile was added, and the mixture was refluxed for 5 hours to polymerize. Hexane was added to the resulting reaction mixture to precipitate a copolymer. The precipitate was filtered and then vacuum-dried to obtain Coating Resin 1. 30 parts of the resulting Coating Resin 1 were dissolved in 40 parts of toluene and 30 parts of methyl ethyl ketone to obtain Polymer Solution 1 (solids content 30% by mass).

[0208] <Preparation of Coating Resin Solution 1> Polymer solution 1 (resin solids concentration 30%) 33.3% by mass Toluene 66.4% by mass Carbon black (Regal 330; manufactured by Cabot Corporation) 0.3% by mass (Primary particle size 25 nm, nitrogen adsorption specific surface area 94 m 2 / g, DBP oil absorption 75ml / 100g) The resulting dispersion was dispersed for 1 hour using zirconia beads with a diameter of 0.5 mm in a paint shaker. The resulting dispersion was filtered through a 5.0 μm membrane filter to obtain coating resin solution 1.

[0209] <Magnetic Carrier 1 Manufacturing Example> (Resin coating process): Coating resin solution 1 was added to a vacuum degassing kneader maintained at room temperature so that the resin component was 2.5 parts per 100 parts of magnetic core particles 1. After addition, the mixture was stirred at a rotation speed of 30 rpm for 15 minutes, and after a certain amount of solvent (80% by mass) had evaporated, the mixture was heated to 80°C while mixing under reduced pressure, and the toluene was distilled off over 2 hours, after which it was cooled. The obtained magnetic carrier was separated into low-magnetic particles by magnetic separation, passed through a sieve with 70 μm openings, and then classified with an air classifier to obtain magnetic carrier 1 having a 50% particle size (D50) based on volume distribution of 38.2 μm.

[0210] <Production example of two-component developer 1> To 92.0 parts of magnetic carrier 1, 8.0 parts of toner 1 were added and mixed in a V-type mixer (V-20, manufactured by Seishin Enterprises) to obtain two-component developer 1.

[0211] <Production examples of two-component developers 2 to 45> In the production example of two-component developer 1, the same procedure was carried out except that the combination of toners was changed as shown in Table 5, to obtain two-component developers 2 to 45.

[0212] [Table 5]

[0213] Example 1 Evaluation was carried out using the above two-component developer 1. Evaluation was carried out based on the following evaluation methods, and the results are shown in Table 6.

[0214] <Evaluation 1: Evaluation of toner fusion to photosensitive drum> The image forming device was a Canon full-color copier, imagePRESS V1350, modified to a process speed of 650 mm / sec. A two-component developer was placed in the developing unit of the cyan station, and the evaluation was carried out. The evaluation environment was a room temperature, low humidity environment (NL: 23°C, 5% RH), and the evaluation paper was CS-680 (68.0 g / m 2 Paper (A4 size) (sold by Canon Marketing Japan Inc.) was used.

[0215] In a room temperature, low humidity environment, 100,000 sheets of a chart with an image ratio of 1% were continuously printed out. After the 100,000 sheets had been continuously printed, a solid black image was output and the degree of white spots on the solid black image was evaluated. The evaluation was performed according to the following evaluation criteria. (Evaluation criteria) A: No defects were observed on the drum surface or in the image (very good). B: Slight staining is observed on the drum surface, but 1 to 3 white dots are observed on the image (Excellent). C: Some contamination was observed on the drum surface, and 3 to less than 5 white spots appeared on the image (good). D: Slight contamination of the drum surface was observed, with 5 to 7 white dots on the image (a level that is acceptable for the present invention). E: Slight contamination of the drum surface was observed, and 7 or more white spots appeared on the image (not acceptable for the present invention)

[0216] <Evaluation 2: Evaluation of initial HH backside soiling (slip-through of cleaning blade)> The image forming apparatus was a Canon full-color copier, imagePRESS V1350, modified to a process speed of 650 mm / sec. A two-component developer was added to the cyan station's developer unit, and the evaluation was carried out. The evaluation environment was a high-temperature, high-humidity environment (HH: 30°C, 80% RH), and the evaluation paper was CS-680 (68.0 g / m 2 Paper (A4 size) (sold by Canon Marketing Japan Inc.) was used.

[0217] The toner that has slipped through the cleaning blade will stain the back side of a single-sided print. This staining is measured. The initial back side staining was measured using the following procedure.

[0218] The average reflectance Dr (%) of the evaluation paper before image output was measured using a reflectometer ("REFLECTOMETER MODEL TC-6DS" manufactured by Tokyo Denshoku Co., Ltd.).

[0219] An initial (first) print was made using a chart with an image ratio of 80% under a high-temperature, high-humidity environment, and the reflectance Ds (%) of the back surface was measured. The back stain (%) was calculated from the obtained Dr and Ds using the following formula. The obtained back stain was evaluated according to the following evaluation criteria. Backside dirt (%) = Dr (%) - Ds (%) (Evaluation criteria) A: Less than 0.3% (very good) B: 0.3% or more and less than 0.6% (excellent) C: 0.6% or more and less than 0.9% (good) D: 0.9% or more and less than 1.2% (a level that is acceptable for the present invention) E: 1.2% or more (unacceptable in the present invention)

[0220] <Evaluation 3: Image evaluation in a high temperature and humidity environment (HH: 30°C, 80% RH)> The image forming apparatus was a Canon full-color copier, imagePRESS V1350, modified to a process speed of 650 mm / sec. A two-component developer was added to the cyan station's developer unit, and the evaluation was carried out. The evaluation environment was a high-temperature, high-humidity environment (HH: 30°C, 80% RH), and the evaluation paper was CS-680 (68.0 g / m 2 Paper (A4 size) (sold by Canon Marketing Japan Inc.) was used.

[0221] The image used in the paper feed durability test was a full-page halftone image with an image duty of 80%, and a high-duty image durability test was performed. 100,000 chart images with an image duty of 80% were output continuously, and the image density and fog of the image on the 10,000th sheet were evaluated as an initial evaluation. The image density and fog of the image after outputting 100,000 sheets were evaluated as a durability test.

[0222] The image density was evaluated using a full solid image (printing rate 100%).

[0223] For the evaluation of fogging, a solid white image (0% printing rate) was used. The reflectance Dr (%) of the evaluation paper before image printing and the reflectance Ds (%) after image printing were measured using a reflectometer ("REFLECTOMETER MODEL TC-6DS" manufactured by Tokyo Denshoku Co., Ltd.). The fogging rate (%) was calculated from the obtained Dr and Ds using the following formula. Fog rate (%) = Dr (%) - Ds (%) (Evaluation criteria) Image density A: 1.40 or above (very good) B: 1.35 or more and less than 1.40 (excellent) C: 1.30 or more and less than 1.35 (good) D: 1.25 or more and less than 1.30 (a level that is acceptable for the present invention) E: Less than 1.25 (unacceptable in the present invention) ·Fog A: Less than 0.3% (very good) B: 0.3% or more and less than 0.6% (excellent) C: 0.6% or more and less than 0.9% (good) D: 0.9% or more and less than 1.2% (a level that is acceptable for the present invention) E: 1.2% or more (unacceptable in the present invention)

[0224] <Evaluation 4: Image evaluation in a normal temperature and low humidity environment (NL; 23°C, 5% RH)> The image forming apparatus was a Canon imagePRESS V1350 full-color copier, modified to a process speed of 650 mm / sec. A two-component developer was added to the cyan station's developer unit, and the evaluation was carried out. The evaluation environment was a normal temperature and low humidity environment (NL: 23°C, 5% RH), and the evaluation paper was CS-680 (68.0 g / m 2 Paper (A4 size) (sold by Canon Marketing Japan Inc.) was used.

[0225] The image used in the paper feed durability test was a full-page halftone image with an image duty of 1%, and this was used as a low-duty image durability test. 100,000 chart images with an image duty of 1% were output continuously, and the image density and fog of the image on the 10,000th sheet were evaluated as an initial evaluation. The image density and fog of the image after outputting 100,000 sheets were evaluated as a durability test.

[0226] The image density was evaluated using a full solid image (printing rate 100%).

[0227] The fogging was evaluated using a full white image (printing rate 0%). (Evaluation criteria) Image density A: 1.40 or above (very good) B: 1.35 or more and less than 1.40 (excellent) C: 1.30 or more and less than 1.35 (good) D: 1.25 or more and less than 1.30 (a level that is acceptable for the present invention) E: Less than 1.25 (unacceptable in the present invention) ·Fog A: Less than 0.3% (very good) B: 0.3% or more and less than 0.6% (excellent) C: 0.6% or more and less than 0.9% (good) D: 0.9% or more and less than 1.2% (a level that is acceptable for the present invention) E: 1.2% or more (unacceptable in the present invention)

[0228] <Evaluation 5: Image evaluation under normal temperature and humidity conditions (NN; 23°C, 50% RH)> The image forming apparatus was a Canon full-color copier, imagePRESS V1350, modified to a process speed of 650 mm / sec. A two-component developer was added to the cyan station's developer unit, and the evaluation was carried out. The evaluation environment was normal temperature and humidity (NN; 23°C, 50% RH), and the evaluation paper was CS-680 (68.0 g / m 2 Paper (A4 size) (sold by Canon Marketing Japan Inc.) was used.

[0229] The image used in the paper feed durability test was a full-page halftone image with an image duty of 10%, and a medium-duty image durability test was conducted. 100,000 chart images with an image duty of 10% were output continuously, and the image density and fog of the image on the 10,000th sheet were evaluated as an initial evaluation. The image density and fog of the image after outputting 100,000 sheets were evaluated as a durability test.

[0230] The image density was evaluated using a full solid image (printing rate 100%).

[0231] The fogging was evaluated using a full white image (printing rate 0%). (Evaluation criteria) Image density A: 1.40 or above (very good) B: 1.35 or more and less than 1.40 (excellent) C: 1.30 or more and less than 1.35 (good) D: 1.25 or more and less than 1.30 (a level that is acceptable for the present invention) E: Less than 1.25 (unacceptable in the present invention) ·Fog A: Less than 0.3% (very good) B: 0.3% or more and less than 0.6% (excellent) C: 0.6% or more and less than 0.9% (good) D: 0.9% or more and less than 1.2% (a level that is acceptable for the present invention) E: 1.2% or more (unacceptable in the present invention)

[0232] [Examples 2 to 41 and Comparative Examples 1 to 5] Except for changing the developer, evaluation was carried out in the same manner as in Example 1. The evaluation results are shown in Table 6.

[0233] [Table 6-1]

[0234] [Table 6-2]

[0235] In Comparative Example 1, the peripheral speed of the tip of the stirring blade during the mixing step was slow, and the metal titanate compound particles remained aggregated. As a result, the image density and fogging deteriorated after durability testing, particularly in the NL and HH environments, and the objectives of the present invention could not be achieved.

[0236] In Comparative Example 2, the peripheral speed of the tip of the stirring blade during the mixing process was high, and the metal titanate compound particles remained dispersed. As a result, the image density and fogging before and after durability testing in each environment deteriorated, and the goal of the present invention was not achieved.

[0237] In Comparative Example 3, the shear adhesion strength of the metal titanate compound particles was low. When the shear adhesion strength was low, the cohesion strength was weak, making it difficult to selectively adhere the toner particles to the convex portions of the toner particles. As a result, the toner melt-adhesion to the photoreceptor and slip-through during drum photoreceptor cleaning deteriorated, and the image density and fogging after endurance testing in various environments also deteriorated. This failed to achieve the objectives of the present invention.

[0238] In Comparative Example 4, the shear adhesive force of the metal titanate compound particles was large. High shear adhesive force resulted in strong cohesion, making it difficult to selectively adhere to the toner particle convex portions. As a result, toner melting and slipping through the photoreceptor during drum photoreceptor cleaning was further exacerbated, resulting in poor image density and fogging after endurance testing in various environments, failing to achieve the objectives of the present invention.

[0239] The toner particle density was low in Comparative Example 5. As a result, the toner melt-adhesion to the photoreceptor and slip-through became worse during drum photoreceptor cleaning, and the image density and fogging before and after durability testing in each environment also worsened, failing to achieve the goal of the present invention. [Explanation of symbols]

[0240] 101: supply port, 102: volute chamber, 103: rotor, 104: stator, 105: rear chamber, 106: discharge port, 107: rotating shaft, 108: cold air generator, 109: cold water supply port, 110: cold water discharge port, 231: pulverizer, 232: classifier, 233: raw material feeder, 234: conveying pipe, 235: nozzle, 236: collision plate, 237: pulverizing chamber, 238: collector, 239: main body hopper section, 240: center core, 241: Separate core, 242: Discharge pipe, 243: Secondary air supply port, 301: Raw material constant volume supply means, 302: Compressed gas flow rate adjustment means, 303: Inlet pipe, 304: Projecting member, 305: Supply pipe, 306: Treatment chamber, 307: Hot air supply means, 308: Cold air supply means, 309: Regulating means, 310: Recovery means, 311: Hot air supply means outlet, 312: Distribution member, 313: Swirling member, 314: Powder particle supply port

Claims

1. A toner manufacturing method including a mixing step of stirring and mixing toner particles containing a binder resin and a colorant with a processing target containing metal titanate compound particles, the toner particles have a density of 0.90 or more and 0.99 or less; the metal titanate compound particles have a shear adhesive strength of 4000 Pa or more and 10000 Pa or less, The method for producing a toner is characterized in that the mixing step is a step of stirring and mixing the material to be treated by using a mixing device having a mixing tank and a rotatable stirring blade provided in the mixing tank, and rotating the stirring blade in the mixing tank at a tip peripheral speed of 30 m / s or more and 70 m / s or less.

2. 2. The method for producing a toner according to claim 1, wherein the metal titanate compound particles are selected from the group consisting of strontium titanate particles, calcium titanate particles, magnesium titanate particles, and zinc titanate particles.

3. 3. The method for producing a toner according to claim 1, wherein the metal titanate compound particles are treated with a silane coupling agent.

4. 3. The method for producing a toner according to claim 1, wherein the metal titanate compound particles are treated with silicone oil.

5. 3. The method for producing a toner according to claim 1, wherein the metal titanate compound particles are treated with a silane coupling agent and silicone oil.

6. 4. The method for producing a toner according to claim 3, wherein the silane coupling agent is an alkyltrialkoxysilane having an alkyl group having 3 to 6 carbon atoms.

7. 3. The method for producing a toner according to claim 1, wherein the metal titanate compound particles have a number average particle diameter of 10 nm or more and 500 nm or less.

8. 3. The method for producing a toner according to claim 1, wherein the toner contains silica fine particles having a number average particle diameter of 50 nm or more and 200 nm or less.

Images