Toner for electrostatic image development, electrostatic image developer, toner cartridge, process cartridge, and image forming apparatus

Abstract

To provide a toner for electrostatic charge image development that prevents faulty cleaning of an image carrier when images with a high image density are formed continuously at high speed.SOLUTION: A toner for electrostatic charge image development contains alkylsilane-treated silica particles, cyclic siloxane, and toner particles.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Patent Document 1 states, "Particle size (D) measured by laser diffraction method" 50 ) is 300nm or less, particle size distribution index (D 90 / D 10 A hydrophobic silica powder has been proposed, having a pH of 3.0 or less, a degree of hydrophobicity of 60% by volume or more, and an organic acid content of 1 to 300 ppm. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-142959 [Overview of the initiative] [Problems that the invention aims to solve]

[0004] The object of the present invention is to provide an electrostatic image developing toner containing alkylsilane-treated silica particles and toner particles that suppresses cleaning defects of the image holder when forming images with high image density (e.g., image density of 90% or more) continuously and at high speed, compared to a toner that does not contain cyclic siloxane. [Means for solving the problem]

[0005] The means to solve the above problems include the following: <1> Alkylsilane-treated silica particles and Cyclic siloxanes and Toner for electrostatic image development containing toner particles. <2> The alkylsilane is at least one selected from the group consisting of alkylsilanes represented by the following formulas (1), (2), and (3). <1> Toner for developing electrostatic images as described above.

[0006] [ka]

[0007] (R1 to R in formula (1) to formula (3) 12 Each of these independently represents an alkyl group having between 1 and 3 carbon atoms. <3> The alkyl group in the aforementioned alkylsilane is entirely a methyl group. <2> Toner for developing electrostatic images as described above. <4> The cyclic structure of the cyclic siloxane is composed of 3 to 6 siloxane units. <1> ~ <3> A toner for developing electrostatic images, as described in one of the following. <5> The cyclic siloxane having 3 to 6 siloxane units has a methyl group. <4> Toner for developing electrostatic images as described above. <6> The content of the cyclic siloxane is 10 ppm or more and 1000 ppm or less relative to the total amount of silica particles. <1> ~ <5> A toner for developing electrostatic images, as described in one of the following. <7> The ratio of the content of the cyclic siloxane to the amount of surface treatment of the alkylsilane (content of cyclic siloxane / amount of surface treatment of alkylsilane) is 0.0001 or more and 0.01 or less. <1> ~ <6> A toner for developing electrostatic images, as described in one of the following. <8> The cyclic siloxane is contained in the silica particles. <1> ~ <7> A toner for developing electrostatic images, as described in one of the following. <9> Contains strontium titanate particles with an average primary particle size of 10 nm to 100 nm. <1> ~ <8> A toner for developing electrostatic images, as described in one of the following. <10> The average primary particle size of the strontium titanate particles (average primary particle size of strontium titanate particles / average primary particle size of silica particles) is 0.01 or more and 2.0 or less relative to the average primary particle size of the silica particles. <9> Toner for developing electrostatic images as described above. <11> The content of strontium titanate particles relative to the content of silica particles (content of strontium titanate particles / content of silica particles) is 0.01 or more and 1.0 or less. <9> or <10> Toner for developing electrostatic images as described above. <12> <1> ~ <11> A electrostatic image developer containing an electrostatic image developing toner as described in any one of the following. <13> <1> ~ <11> It contains the electrostatic image developing toner described in one of the following: A toner cartridge that is attached to and detached from an image forming machine. <14> <12> The development means contains the electrostatic image developer described above, and develops the electrostatic image formed on the surface of the image holder as a toner image using the electrostatic image developer, A process cartridge that is attached to and detached from an image forming apparatus. <15> Image holder and, A charging means for charging the surface of the image holder, A means for forming an electrostatic image on the surface of the charged image holder, <12> A developing means containing the electrostatic image developer described above, and developing the electrostatic image formed on the surface of the image holder as a toner image using the electrostatic image developer, A transfer means for transferring a toner image formed on the surface of the image holder to the surface of a recording medium, Fixing means for fixing the toner image transferred to the surface of the recording medium, An image forming apparatus equipped with the following features. [Effects of the Invention]

[0008] <1> or <2> According to the invention, an electrostatic image developing toner is provided which includes alkylsilane-treated silica particles and toner particles, and which suppresses cleaning defects of the image holder when a high-density image is formed continuously and at high speed, compared to a case that does not contain cyclic siloxane. According to the invention defined in <3>, compared with the case where the alkylsilane is triethylmethoxysilane, there is provided a toner for developing electrostatic images that suppresses poor cleaning of an image bearing member when forming images with high image density continuously at high speed. According to the invention defined in <4>, compared with the case where the number of siloxane units constituting the cyclic structure of the cyclic siloxane exceeds 6, there is provided a toner for developing electrostatic images that suppresses poor cleaning of an image bearing member when forming images with high image density continuously at high speed. According to the invention defined in <5>, compared with the case where the cyclic siloxane having 3 or more and 6 or less siloxane units has an ethyl group, there is provided a toner for developing electrostatic images that suppresses poor cleaning of an image bearing member when forming images with high image density continuously at high speed.

[0009] According to the invention defined in <6>, compared with the case where the content of the cyclic siloxane is less than 10 ppm or more than 1000 ppm based on the total mass of the silica particles, there is provided a toner for developing electrostatic images that suppresses poor cleaning of an image bearing member when forming images with high image density continuously at high speed. According to the invention defined in <7>, compared with the case where the ratio of the content of the cyclic siloxane to the surface treatment amount of the alkylsilane (content of cyclic siloxane / surface treatment amount of alkylsilane) is less than 0.0001 or more than 0.01, there is provided a toner for developing electrostatic images that suppresses poor cleaning of an image bearing member when forming images with high image density continuously at high speed. According to the invention defined in <8>, compared with the case where the cyclic siloxane is contained in a component other than the silica particles, there is provided a toner for developing electrostatic images that suppresses poor cleaning of an image bearing member when forming images with high image density continuously at high speed. According to the invention defined in <9>, compared with the case containing strontium titanate particles having an average primary particle diameter of less than 10 nm or containing strontium titanate particles having an average primary particle diameter of more than 100 nm, there is provided a toner for developing electrostatic images that suppresses poor cleaning of an image bearing member when forming images with high image density continuously at high speed. According to the invention according to <10>, compared with the case where the ratio of the average primary particle diameter of the strontium titanate particles to the average primary particle diameter of the silica particles (average primary particle diameter of strontium titanate particles / average primary particle diameter of silica particles) is less than 0.01 or more than 2.0, there is provided a toner for developing electrostatic images that suppresses poor cleaning of an image carrier when forming continuous, high-speed images with high image density.

[0010] According to the invention according to <11>, compared with the case where the ratio of the content of the strontium titanate particles to the content of the silica particles (content of strontium titanate particles / content of silica particles) is less than 0.01 or more than 1.0, there is provided a toner for developing electrostatic images that suppresses poor cleaning of an image carrier when forming continuous, high-speed images with high image density. According to the invention according to <12>, <13>, <14> or <15>, in a toner for developing electrostatic images comprising alkylsilane-treated silica particles and toner particles, compared with the case where the toner for developing electrostatic images contains no cyclic siloxane, there is provided an electrostatic charge image developer, a toner cartridge, a process cartridge or an image forming apparatus that includes a toner for developing electrostatic images that suppresses poor cleaning of an image carrier when forming continuous, high-speed images with high image density. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] [Figure 1] It is a schematic configuration diagram showing the image forming apparatus according to the present embodiment. [Figure 2] It is a schematic configuration diagram showing the process cartridge according to the present embodiment. MODES FOR CARRYING OUT THE INVENTION

[0012] Hereinafter, embodiments which are examples of the present invention will be described. These descriptions and examples are intended to exemplify embodiments, and do not limit the scope of the invention. In numerical ranges described stepwise within this specification, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described stepwise. Furthermore, in numerical ranges described within this specification, the upper or lower limit of that range may be replaced with the values ​​shown in the examples.

[0013] Each component may contain multiple types of the relevant substance. When referring to the amount of each component in a composition, if there are multiple substances corresponding to each component in the composition, unless otherwise specified, it refers to the total amount of those multiple substances present in the composition.

[0014] <Toner for developing electrostatic images> The electrostatic image developing toner (hereinafter also referred to as "toner") according to this embodiment comprises alkylsilane-treated silica particles, a cyclic siloxane, and toner particles.

[0015] The toner according to this embodiment, with the above configuration, suppresses cleaning defects of the image holder when high-density images are formed continuously and at high speed. The reason for this is presumed to be as follows.

[0016] From the viewpoint of toner fluidity, toner charge control, and cleaning maintenance, hydrophobically treated silica particles are sometimes used as an external additive. The externally added silica particles are released from the toner particles by mechanical loads such as agitation in the developing mechanism and scraping at the cleaning nip. When the silica particles released from the toner particles reach the cleaning nip, they are dammed at the tip of the cleaning nip (the part downstream in the direction of rotation of the image holder at the contact point between the cleaning blade and the image holder), and the pressure from the cleaning blade causes the external additive to accumulate between the cleaning blade and the image holder (hereinafter, this accumulation of external additive is referred to as the "external additive dam"), thereby improving the toner scraping performance. As a result, the occurrence of toner slippage from the cleaning nip (cleaning failure) is suppressed, and cleaning performance can be maintained. Here, cleaning maintenance (the maintenance of suppression of cleaning failure) is influenced by the strength of the external additive dam. To improve cleaning performance, linear silicone oil is sometimes added to the silica particles. However, when high-density images are formed continuously and at high speed, the amount of linear silicone oil supplied to the external additive dam can become too large, causing the strength of the dam to increase excessively. This is thought to be because the linear silicone oil is easily released from the silica particles when subjected to pressure from the cleaning blade. Consequently, when high-density images are formed continuously and at high speed, a large amount of untransferred toner remains on the image carrier. This large amount of untransferred toner reaches the cleaning nip and is dammed up by the external additive dam. This can cause micro-vibrations of the cleaning blade during image formation, leading to toner slipping out of the cleaning nip and resulting in poor cleaning. Furthermore, if the strength of the external additive dam is weak, when high-density images are formed continuously and at high speed, a large amount of untransferred toner remains on the image carrier. When a large amount of untransferred toner reaches the cleaning nip, the external additive dam may collapse, causing the toner to leak out of the cleaning nip, i.e., resulting in poor cleaning.

[0017] The toner according to this embodiment contains a cyclic siloxane along with alkylsilane-treated silica particles. By using this configuration, the cyclic siloxane is released from the toner particles together with the alkylsilane-treated silica particles and reaches the cleaning nip. Furthermore, when a high-density image is formed continuously and at high speed, the pressure from the cleaning blade causes the cyclic siloxane to be released from the alkylsilane-treated silica particles in a moderate and continuous manner, rather than being released in large quantities all at once. This is thought to be because the cyclic portion of the cyclic siloxane easily intertwines with the alkyl group contained in the alkylsilane-treated silica particles. Therefore, when high-density images are formed continuously and at high speed, the amount of cyclic siloxane supplied to the external additive dam is maintained at an appropriate level over time. This makes it easier to maintain the strength of the external additive dam, thus improving cleaning performance.

[0018] From the above, it is presumed that the toner according to this embodiment suppresses cleaning defects of the image holder when a high-density image is formed continuously and at high speed.

[0019] (Alkylsilane-treated silica particles) The toner according to this embodiment contains alkylsilane-treated silica particles. Alkylsilane-treated silica particles are silica particles that have been surface-treated with alkylsilane. Hereinafter, the silica particles to be surface-treated with alkylsilane can be any particles whose main component is silica, i.e., SiO2. In this specification, "main component" refers to a component that accounts for 50% or more of the total mass of a mixture of multiple components.

[0020] Alkylsilanes are silicon compounds that have an alkyl group directly bonded to a silicon atom. The alkyl group of the alkylsilane preferably has 1 to 3 carbon atoms, more preferably 1 to 2 carbon atoms, and even more preferably 1 carbon atom.

[0021] The alkylsilane is preferably a silicon compound having an alkyl group and an alkoxy group, and more preferably a compound consisting of an alkyl group, an alkoxy group and a silicon atom.

[0022] The preferred numerical range for the number of carbon atoms in the alkoxy group is the same as the numerical range for the number of carbon atoms in the alkyl group of the alkylsilane.

[0023] The number of alkyl groups in the alkylsilane is preferably one to three per silicon atom, more preferably one or three, and even more preferably three. The number of alkoxy groups in the alkylsilane is preferably one to three per silicon atom, more preferably one or three, and even more preferably one.

[0024] The alkylsilane is preferably at least one selected from the group consisting of alkylsilanes represented by the following formulas (1), (2), and (3).

[0025] [ka]

[0026] In formulas (1) to (3), R1 to R 12 Each of these independently represents an alkyl group having 1 to 3 carbon atoms. R1~R 12 The preferred numerical range for the number of carbon atoms in the alkyl group represented by is the same as the numerical range for the number of carbon atoms in the alkyl group of the alkylsilane.

[0027] In formula (1), R1 to R4 are preferably at least one selected from the group consisting of a methyl group, an ethyl group, and a propyl group, and it is more preferable that all of R1 to R4 are methyl groups. In formula (2), R5 to R8 are preferably at least one selected from the group consisting of a methyl group, an ethyl group, and a propyl group, and it is more preferable that all of R5 to R8 are methyl groups. In formula (3), R9~R 12 It is preferable that R9~R be at least one selected from the group consisting of methyl, ethyl, and propyl groups. 12 It is more preferable that all of them are methyl groups.

[0028] By applying at least one alkylsilane selected from the group consisting of alkylsilanes represented by formulas (1) to (3) above, cleaning defects of the image holder are further suppressed when high-density images are formed continuously and at high speed. It is presumed that alkylsilanes represented by formulas (1) to (3) above are more likely to intertwine with the cyclic portion of cyclic siloxanes.

[0029] From the viewpoint of further suppressing cleaning defects, the alkylsilane is preferably an alkylsilane represented by formula (1) or formula (3) above, and more preferably an alkylsilane represented by formula (3) above.

[0030] It is preferable that all alkyl groups in the alkylsilane represented by formulas (1) to (3) are methyl groups. When all alkyl groups in the alkylsilanes represented by formulas (1) to (3) are methyl groups, steric hindrance is small, making it easier to uniformly distribute the material on silica particles and to intertwine more easily with the cyclic portion of the cyclic siloxane. Therefore, it is presumed that the cyclic siloxane is released gradually and continuously rather than in large quantities at once, thus further suppressing cleaning defects of the image holder when high-density images are formed continuously and at high speed.

[0031] The content of alkylsilane-treated silica particles is preferably 0.01% to 10% by mass, more preferably 0.05% to 5% by mass, and even more preferably 0.1% to 3% by mass, relative to the mass of toner particles.

[0032] -Method for producing alkylsilane-treated silica particles- Alkylsilane-treated silica particles are produced through the process of manufacturing silica matrix particles and then undergoing alkylsilane treatment.

[0033] • Manufacturing of silica matrix particles Silica matrix particles are preferably manufactured by a wet process. The "wet process" is distinct from the gas-phase process and is a method of production that involves neutralizing sodium silicate with mineral acid or hydrolyzing alkoxysilane. Among wet processes, silica matrix particles are preferably produced by the sol-gel method.

[0034] The following describes the method for producing silica matrix particles, using the sol-gel method as an example. Furthermore, the method for producing silica matrix particles is not limited to this sol-gel method. The particle size of the silica matrix particles can be freely controlled by the weight ratio of alkoxysilane, ammonia, alcohol, and water in the hydrolysis and condensation polymerization steps of the sol-gel method, as well as the reaction temperature, stirring speed, and supply speed.

[0035] The following describes in detail the method for producing silica matrix particles using the sol-gel method. Specifically, tetramethoxysilane is added dropwise while heating and stirring in the presence of water and alcohol, with aqueous ammonia as a catalyst. Next, the solvent is removed from the silica sol suspension obtained by the reaction, and the silica matrix particles are dried to obtain the desired silica matrix particles.

[0036] • Alkylsilane treatment Methods for treating with alkylsilane include: a method using supercritical carbon dioxide to dissolve alkylsilane in supercritical carbon dioxide and deposit the alkylsilane onto the surface of silica mother particles; a method in which a solution containing alkylsilane and a solvent that dissolves alkylsilane is applied (e.g., by spraying or coating) to the surface of silica mother particles in the atmosphere to deposit the alkylsilane onto the surface of silica mother particles; and a method in which a solution containing alkylsilane and a solvent that dissolves alkylsilane is added to a silica mother particle dispersion in the atmosphere, held, and then dried the mixed solution of the silica mother particle dispersion and the solution.

[0037] (Cyclic siloxane) The toner according to this embodiment contains a cyclic siloxane. A cyclic siloxane is a compound that has a cyclic structure composed of multiple siloxane units. Here, a siloxane unit refers to the constituent unit represented by the following formula (4).

[0038] [ka]

[0039] In equation (4), * represents a bond. The functional groups that can bond to the bond represented by * are not particularly limited, but examples include hydrogen atoms, hydrocarbon groups, phenyl groups, and groups containing polyethers. From the viewpoint of further suppressing cleaning defects, the functional group bonded to the bond represented by * is preferably a hydrocarbon group, and more preferably an alkyl group. From the viewpoint of further suppressing cleaning defects, the functional group that binds to the bond represented by * is preferably a methyl group, an ethyl group, or a propyl group, and more preferably a methyl group. Note that the functional groups attached to the bonds represented by * may be the same or different.

[0040] The number of siloxane units constituting the cyclic structure of the cyclic siloxane is preferably 3 to 6, more preferably 4 to 6, and even more preferably 5 to 6.

[0041] By setting the number of siloxane units constituting the cyclic structure of the cyclic siloxane to between 3 and 6, cleaning defects of the image holder are further suppressed when high-density images are formed continuously and at high speed. The reason for this is presumed to be as follows. By setting the number of siloxane units constituting the cyclic structure of the cyclic siloxane to three or more, the ring structure of the cyclic siloxane becomes stable, and the cyclic portion of the cyclic siloxane becomes more easily intertwined with the alkyl group contained in the alkylsilane-treated silica particles, thus moderately suppressing the release of cyclic siloxane from the alkylsilane-treated silica particles. Furthermore, by setting the number of siloxane units constituting the cyclic structure of the cyclic siloxane to six or less, the degree of freedom of the cyclic siloxane's ring structure is moderately suppressed, and because the cyclic portion is of an appropriate size, it becomes more easily intertwined with the alkyl group contained in the alkylsilane-treated silica particles, thus moderately suppressing the release of cyclic siloxane from the alkylsilane-treated silica particles.

[0042] It is preferable that the cyclic structure of the cyclic siloxane has 3 to 6 siloxane units and that it has a methyl group. In other words, it is preferable that the cyclic siloxane has 3 to 6 siloxane units that constitute its cyclic structure and that it has a methyl group. The presence of a methyl group in cyclic siloxanes with 3 to 6 siloxane units constituting the cyclic structure of the cyclic siloxane further suppresses cleaning defects of the image holder when high-density images are formed continuously and at high speed. The reason for this is presumed to be as follows. When a cyclic siloxane has 3 to 6 siloxane units constituting its cyclic structure, the presence of a methyl group reduces steric hindrance compared to cases containing ethyl groups, propyl groups, etc. This facilitates entanglement between the cyclic structure of the cyclic siloxane and the alkyl group contained in the alkylsilane-treated silica particles, thereby moderately suppressing the release of the cyclic siloxane.

[0043] Examples of cyclic siloxanes include hexamethylcyclotrisiloxane and dodecamethylcyclohexanesiloxane, and dodecamethylcyclohexanesiloxane is preferred from the viewpoint of further suppressing cleaning defects.

[0044] Cyclic siloxanes are preferably included in alkylsilane-treated silica particles. The inclusion of cyclic siloxanes in alkylsilane-treated silica particles further suppresses cleaning defects of the image holder when high-density images are formed continuously and at high speed. It is presumed that the presence of cyclic siloxanes in alkylsilane-treated silica particles makes it easier for the alkyl groups derived from the alkylsilane and the cyclic siloxanes to come into close proximity and thus become more likely to intertwine.

[0045] One method for incorporating cyclic siloxanes into alkylsilane-treated silica particles is to perform alkylsilane treatment of silica particles using supercritical carbon dioxide, in which the alkylsilane is dissolved in supercritical carbon dioxide, and then, after a certain period of time, the cyclic siloxane is dissolved in the supercritical carbon dioxide.

[0046] (Amount of surface treatment of alkylsilane and content of cyclic siloxane) -Cyclic siloxane content- The cyclic siloxane content is preferably 10 ppm to 1000 ppm, more preferably 10 ppm to 500 ppm, and even more preferably 10 ppm to 300 ppm, relative to the total alkylsilane-treated silica particles.

[0047] By setting the cyclic siloxane content to between 10 ppm and 1000 ppm relative to the total alkylsilane-treated silica particles, cleaning defects of the image holder are further suppressed when high-density images are formed continuously and at high speed. The reason for this is presumed to be as follows. By setting the cyclic siloxane content to 10 ppm or more, it is presumed that the cyclic siloxane is present in an amount sufficient for the alkyl group derived from the alkylsilane to intertwine sufficiently. By setting it to 1000 ppm or less, it is presumed that the cyclic siloxane is present in an amount that makes it difficult for the cyclic structure of the cyclic siloxane to intertwine with the alkyl group derived from the alkylsilane due to steric hindrance, while also preventing it from easily detaching from the alkylsilane-treated silica particles. Therefore, the amount of cyclic siloxane supplied to the external additive dam will be an amount that moderately improves the strength of the external additive dam.

[0048] The cyclic siloxane content in alkylsilane-treated silica particles is calculated using the following procedure. Specifically, the "cyclic siloxane content per 10g of toner" and the "cyclic siloxane content per 10g of toner" are calculated, and from these values, the "cyclic siloxane content relative to alkylsilane-treated silica particles" is calculated.

[0049] (Calculation of cyclic siloxane content per 10g of toner) 10 g of the toner to be measured is added to 100 ml of a 0.5% aqueous solution of a surfactant (preferably sodium alkylbenzenesulfonate) to obtain a toner dispersion. The dispersion is dispersed using an ultrasonic disperser for 5 minutes, and the dispersion is filtered using a 0.5 μm mesh filter to separate the toner particles. After measuring the mass of the dried filtrate obtained by drying the filtrate, 200 mg of the dried filtrate is weighed out and the cyclic siloxane content is analyzed using a headspace gas scuttogram mass spectrometer (Shimadzu Corporation GCMS-QP2020). 200 mg of the dried filtrate is weighed into a vial and heated to 190°C for 3 minutes. The volatile components in the vial are then introduced into a column (RTX-1, film thickness 1 μm, inner diameter 0.32 mm, length 60 m), and the measurement is performed under the following column separation conditions. The peak detection amount at a retention time of 14 minutes is converted to n-hexane and expressed as the cyclic siloxane content per 200 mg of filtrate dry product. Column separation conditions: Initial temperature 40°C, hold for 5 minutes, heating to 250°C at a rate of 5 minutes / minute, hold at 250°C for 11 minutes. Pressure 120 Pa, purge flow rate 30 ml / min. Ion source temperature 260°C, interface temperature 260°C. The cyclic siloxane content per 200 mg of filtrate dry material calculated using the above procedure is converted to a value per total amount of filtrate dry material, and this value is taken as the cyclic siloxane content per 10 g of toner.

[0050] (Content of alkylsilane-treated silica particles per 10g of toner) Next, we calculate the amount of alkylsilane-treated silica particles per 10g of toner. Furthermore, the content of alkylsilane-treated silica particles in the toner will be analyzed using the X-ray fluorescence measurement method described below. First, 150 mg of the toner to be measured is accurately weighed, and then a 10 mm diameter, disc-shaped sample is prepared by pressurizing it in a pressure molding machine at 5 t / cm² for 1 minute. Next, the prepared sample is subjected to a wavelength-dispersive X-ray fluorescence analyzer XRF-1500 (manufactured by Shimadzu Corporation) under the following measurement conditions: Rh target, tube voltage 40KV, tube current 70mA, and measurement time 30 minutes. The Net intensity (kcps) value, which represents the amount of X-rays generated from each element, is then measured. On the other hand, seven levels of toner are prepared in advance: six levels with varying amounts of silica particles (0.5% by mass, 1% by mass, 2% by mass, 5% by mass, 10% by mass, and 20% by mass (all representing the amount of silica particles added relative to the toner particles)) and toner without silica particles. A calibration curve is then created showing the correlation between the amount of silica particles added and the Net intensity value of the fluorescent X-rays. Based on this approximation formula, the amount of alkylsilane-treated silica particles per 10g of toner is calculated from the Net intensity (kcps) value of the sample being measured.

[0051] (Calculation of cyclic siloxane content in alkylsilane-treated silica particles) Using the "cyclic siloxane content per 10g of toner" and the "alkylsilane-treated silica particle content per 10g of toner" calculated in the above procedure, the cyclic siloxane content relative to the alkylsilane-treated silica particles is calculated using the following formula and expressed in ppm. Formula: Content of cyclic siloxane in alkylsilane-treated silica particles = (Content of cyclic siloxane per 10g of toner / Content of alkylsilane-treated silica particles per 10g of toner)

[0052] -Ratio (Cyclic siloxane content / Amount of alkylsilane surface treatment)- The ratio of the cyclic siloxane content to the amount of alkylsilane surface treatment (cyclic siloxane content / alkylsilane surface treatment amount) is preferably 0.0001 or more and 0.01 or less, more preferably 0.0003 or more and 0.01 or less, and even more preferably 0.0005 or more and 0.006 or less.

[0053] By setting the ratio (cyclic siloxane content / alkylsilane surface treatment amount) to 0.0001 or higher, it is presumed that the cyclic siloxane content is sufficient to ensure that the alkyl group derived from the alkylsilane and the cyclic portion of the cyclic siloxane are sufficiently intertwined. By setting the ratio (cyclic siloxane content / alkylsilane surface treatment amount) to 0.01 or less, the amount of cyclic siloxane relative to the alkyl group derived from alkylsilane becomes appropriate. Therefore, it is presumed that the steric hindrance between cyclic siloxanes is suppressed, and the amount of cyclic siloxane is sufficient to allow the alkyl group derived from alkylsilane and the cyclic portion of the cyclic siloxane to intertwine adequately. Therefore, it is presumed that the amount of cyclic siloxane supplied to the external additive dam will be sufficient to moderately improve the strength of the external additive dam. Based on the above, by keeping the ratio (cyclic siloxane content / alkylsilane surface treatment amount) within the above numerical range, cleaning defects of the image holder are further suppressed when high-density images are formed continuously and at high speed.

[0054] The ratio (cyclic siloxane content / alkylsilane surface treatment amount) is calculated by dividing the "cyclic siloxane content relative to alkylsilane-treated silica particles," calculated using the procedure above, by the "alkylsilane surface treatment amount," calculated using the procedure below. The units for both "cyclic siloxane content relative to alkylsilane-treated silica particles" and "alkylsilane surface treatment amount" are "mass%."

[0055] The amount of alkylsilane surface-treated can be measured by the amount charged or as follows. If the alkylsilane used in the surface treatment of the alkylsilane-treated silica particles to be measured has not been identified, the alkylsilane used in the surface treatment can be identified using pyrolysis GC-MS (Shimadzu Corporation GCMS-QP2020 / Frontier Lab Co., Ltd. PY2020D). The measurement conditions are as follows: an UltraALLOY-5 column (inner diameter 0.25 mm, film thickness 0.25 μm, length 30 m) is used, the oven temperature is 50°C, the vaporization chamber temperature is 310°C, and the separation conditions are: heating at a rate of 10°C / min to 310°C, followed by a 30-minute hold. The ion source is 200°C and the interface temperature is 310°C, and the MS spectrum is acquired from elution time 1.5 minutes onwards to identify the alkylsilane. Surface-treated silica particles with varying amounts of alkylsilane surface treatment are prepared as standard samples. The standard samples are prepared according to the following procedure.

[0056] • Preparation of standard samples Prepare silica particles produced by the sol-gel method with the same particle size as the alkylsilane-treated silica particles to be measured. Prepare an autoclave with a stirrer (capacity 500 ml) and a device equipped with a back pressure valve, and put the silica particles into the autoclave. Then, fill the autoclave with liquefied carbon dioxide. Next, operate the stirrer and raise the temperature to 170°C with a heater, then increase the pressure to 20 MPa with a carbon dioxide pump. Next, when the amount of supercritical carbon dioxide flowed (cumulative value: measured as the amount of carbon dioxide flowing under standard conditions) reaches 20 L, stop the flow of supercritical carbon dioxide, and then add the same alkylsilane used for surface treatment of the alkylsilane-treated silica particles to be measured. Subsequently, the temperature was maintained at 170°C using a heater and the pressure at 20 MPa using a carbon dioxide pump, maintaining the supercritical state of carbon dioxide in the autoclave while the agitator was operated and the mixture was held for 30 minutes. After 30 minutes, supercritical carbon dioxide was circulated again, the pressure was released to atmospheric pressure through the back pressure valve, and the mixture was cooled to room temperature. After that, the standard sample was removed from the autoclave. Following the procedure described above, surface-treated silica particles with different amounts of alkylsilane surface treatment are prepared as standard samples. Specifically, surface-treated silica particles with alkylsilane surface treatment amounts of 0 mass, 5 mass, 10 mass, 20 mass, 30 mass, 40 mass, and 50 mass% are prepared as standard samples (in all cases, the amount of alkylsilane surface treatment is the mass of alkylsilane used for surface treatment relative to the total mass of the surface-treated silica particles).

[0057] A calibration curve is created by measuring the amount of alkylsilane treatment on a standard sample using TG-DTA (Shimadzu Corporation DTG-60). The measurement conditions for TG-DTA are as follows: The temperature is raised to 600°C at a heating rate of 10°C / min and held at 600°C for 10 minutes. A calibration curve is created using the difference between the absolute mass loss when the temperature is raised to 600°C and the absolute mass loss when the temperature is raised to 180°C (i.e., "absolute mass loss when the temperature is raised to 600°C - absolute mass loss when the temperature is raised to 180°C") as the amount of alkylsilane treatment. This calibration curve is represented as a graph with the amount of alkylsilane treatment (i.e., "absolute mass loss when the temperature is raised to 600°C - absolute mass loss when the temperature is raised to 180°C") on the vertical axis and the surface treatment amount of alkylsilane on the standard sample on the horizontal axis.

[0058] 10 g of the toner to be measured is added to 100 ml of a 0.5% aqueous solution of a surfactant (preferably sodium alkylbenzenesulfonate) to obtain a toner dispersion. The dispersion is dispersed using an ultrasonic disperser for 5 minutes, and the dispersion is filtered using a 0.5 μm mesh filter to separate the toner particles. The alkylsilane-treated silica particles are recovered by drying the filtrate. 1 g of the recovered alkylsilane-treated silica particles is washed with 100 ml of methanol and thoroughly dried. The amount of alkylsilane treatment (i.e., "absolute value of mass loss when heated to 600°C - absolute value of mass loss when heated to 180°C") is measured under the same conditions as the measurement of the standard sample, and the amount of alkylsilane surface treatment (i.e., the mass of alkylsilane used for surface treatment relative to the total mass of alkylsilane-treated silica particles; unit is mass %) is calculated from the calibration curve.

[0059] (Strontium titanate particles) The toner according to this embodiment preferably contains strontium titanate particles. The average primary particle size of the strontium titanate particles is preferably 10 nm to 100 nm, more preferably 20 nm to 80 nm, even more preferably 20 nm to 60 nm, and particularly preferably 30 nm to 60 nm.

[0060] By setting the average primary particle size of strontium titanate particles to between 10 nm and 100 nm, cleaning defects of the image holder are further suppressed when high-density images are formed continuously and at high speed. The reason for this is presumed to be as follows. Because strontium titanate particles have a small electrostatic repulsion with alkylsilane-treated silica particles, they are released from the toner particles along with the alkylsilane-treated silica particles and reach the cleaning nip area, where they are contained within the external dam. When high-density images are formed continuously and at high speed, the pressure from the cleaning blade causes the alkylsilane-treated silica particles and strontium titanate particles to collide appropriately within the external dam, forming a densely packed structure. This allows the alkylsilane-treated silica particles to be retained within the external dam and also assists in the moderate and continuous release of cyclic siloxanes from the alkylsilane-treated silica particles. By setting the average primary particle size of strontium titanate particles to 10 nm or more, they are more easily released from toner particles and incorporated into the external dam. The collision energy when they collide with silica particles promotes the release of cyclic siloxanes from alkylsilane-treated silica particles. By setting the average primary particle size of strontium titanate particles to 100 nm or less, the collision energy with silica in the external dam does not become too strong, and cyclic siloxanes from alkylsilane-treated silica are released moderately and continuously, rather than in large quantities at once, and are retained without being discharged.

[0061] The method for measuring the average primary particle size of strontium titanate particles will be described later.

[0062] The average primary particle size of strontium titanate particles can be controlled, for example, by various conditions during the wet manufacturing process of strontium titanate particles.

[0063] From the viewpoint of excellent transfer retention, the shape of strontium titanate particles is preferably rounded rather than cubic or rectangular.

[0064] It is preferable that strontium titanate particles are doped with metallic elements other than titanium and strontium (hereinafter also referred to as dopants). The presence of dopants in strontium titanate particles reduces the crystallinity of the perovskite structure, resulting in a rounded shape.

[0065] Specific examples of dopants for strontium titanate particles include lanthanides, silica, aluminum, magnesium, calcium, barium, phosphorus, sulfur, calcium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, gallium, yttrium, zinc, niobium, molybdenum, ruthenium, rhodium, palladium, silver, indium, tin, antimony, barium, tantalum, tungsten, rhenium, osmium, iridium, platinum, and bismuth. Lanthanides such as lanthanum and cerium are preferred. Among these, lanthanum is preferred from the viewpoint of being easy to dope and allowing for easy control of the shape of strontium titanate particles.

[0066] From the viewpoint of improving the effect of the strontium titanate particles, it is preferable that the strontium titanate particles have a hydrophobic treated surface, and it is more preferable that the strontium titanate particles have a hydrophobic treated surface with a silicon-containing organic compound.

[0067] -Manufacturing of strontium titanate particles- The wet process for producing strontium titanate particles involves, for example, reacting a mixture of a titanium dioxide source and a strontium source while adding an alkaline aqueous solution, followed by acid treatment. In this process, the particle size of the strontium titanate particles is controlled by factors such as the mixing ratio of the titanium dioxide source and the strontium source, the initial concentration of the titanium dioxide source, and the temperature and rate of addition of the alkaline aqueous solution.

[0068] As a source of titanium dioxide, mineral acid-resolved products of titanium compounds hydrolysates are preferred. As a source of strontium, examples include strontium nitrate and strontium chloride.

[0069] The mixing ratio of the titanium dioxide source and the strontium source is preferably 0.9 to 1.4 in terms of SrO / TiO2 molar ratio, and more preferably 1.05 to 1.20. The initial concentration of the titanium dioxide source as TiO2 is preferably 0.05 mol / L to 1.3 mol / L, and more preferably 0.5 mol / L to 1.0 mol / L.

[0070] From the viewpoint of making the strontium titanate particles rounded rather than cubic or rectangular, it is preferable to add a dopant source to a mixture of a titanium oxide source and a strontium source. Examples of dopant sources include oxides of metals other than titanium and strontium. The metal oxide used as a dopant source is added, for example, as a solution dissolved in nitric acid, hydrochloric acid, or sulfuric acid. The amount of dopant source added is preferably such that the amount of metal in the dopant source is 0.1 moles or more and 20 moles or less per 100 moles of strontium contained in the strontium source, and more preferably 0.5 moles or more and 10 moles or less.

[0071] As the alkaline aqueous solution, an aqueous sodium hydroxide solution is preferred. The higher the temperature of the reaction solution when adding the alkaline aqueous solution, the better the crystalline strontium titanate particles obtained. From the viewpoint of obtaining a rounded shape while having a perovskite-type crystal structure, the temperature of the reaction solution when adding the alkaline aqueous solution is preferably in the range of 60°C to 100°C. The slower the rate of addition of the alkaline aqueous solution, the larger the particle size of the strontium titanate particles obtained, and the faster the rate of addition, the smaller the particle size of the strontium titanate particles obtained. The rate of addition of the alkaline aqueous solution is, for example, 0.001 equivalents / h to 1.2 equivalents / h relative to the raw materials, and 0.002 equivalents / h to 1.1 equivalents / h is appropriate.

[0072] After adding an alkaline aqueous solution, an acid treatment is performed to remove unreacted strontium sources. The acid treatment is carried out using, for example, hydrochloric acid to adjust the pH of the reaction solution to 2.5 to 7.0, more preferably 4.5 to 6.0. After the acid treatment, the reaction solution is separated into solid and liquid components, and the solid components are dried to obtain strontium titanate particles.

[0073] • Surface treatment The surface treatment of strontium titanate particles is carried out, for example, by preparing a treatment solution by mixing a silicon-containing organic compound, which is a hydrophobic treatment agent, with a solvent, mixing the strontium titanate particles with the treatment solution under stirring, and continuing to stir. After the surface treatment, a drying treatment is performed to remove the solvent from the treatment solution.

[0074] Examples of silicon-containing organic compounds used for surface treatment of strontium titanate particles include alkylsilanes, silazane compounds, and silicone oils.

[0075] For surface treatment of strontium titanate particles, the same alkylsilane compounds used for surface treatment of silica particles described above can be applied.

[0076] Examples of silazane compounds used for surface treatment of strontium titanate particles include dimethyldisilazane, trimethyldisilazane, tetramethyldisilazane, pentamethyldisilazane, and hexamethyldisilazane.

[0077] Examples of silicone oils used for surface treatment of strontium titanate particles include silicone oils such as dimethylpolysiloxane, diphenylpolysiloxane, and phenylmethylpolysiloxane; and reactive silicone oils such as amino-modified polysiloxane, epoxy-modified polysiloxane, carboxyl-modified polysiloxane, carbinol-modified polysiloxane, fluorine-modified polysiloxane, methacrylic-modified polysiloxane, mercapto-modified polysiloxane, and phenol-modified polysiloxane.

[0078] As the solvent used to prepare the above-mentioned treatment solution, if the silicon-containing organic compound is alkylsilane, an alcohol (e.g., methanol, ethanol, propanol, butanol) is preferred, and if the silicon-containing organic compound is silicone oil, a hydrocarbon (e.g., benzene, toluene, n-hexane, n-heptane) is preferred.

[0079] In the aforementioned treatment solution, the concentration of the silicon-containing organic compound is preferably 1% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 40% by mass or less, and even more preferably 10% by mass or more and 30% by mass or less.

[0080] The amount of silicon-containing organic compound used for surface treatment is preferably 1 to 50 parts by mass, more preferably 5 to 40 parts by mass, and even more preferably 5 to 30 parts by mass, per 100 parts by mass of strontium titanate particles.

[0081] (Average primary particle size of strontium titanate particles / Average primary particle size of alkylsilane-treated silica particles) When the toner according to this embodiment contains strontium titanate particles, the average primary particle size of the strontium titanate particles (average primary particle size of strontium titanate particles / average primary particle size of alkylsilane-treated silica particles) relative to the average primary particle size of alkylsilane-treated silica particles is preferably 0.01 or more and 2.0 or less, more preferably 0.07 or more and 1.8 or less, and even more preferably 0.1 or more and 1.5 or less.

[0082] By setting the average primary particle size of strontium titanate particles to 0.01 or more and 2.0 or less relative to the average primary particle size of alkylsilane-treated silica particles, cleaning defects of the image holder are further suppressed when high-density images are formed continuously and at high speed. The reason for this is presumed to be as follows. By setting the ratio of the average primary particle diameter of strontium titanate particles to the average primary particle diameter of alkylsilane-treated silica particles to 0.01 or more, collision energy sufficient to appropriately promote the release of cyclic siloxane from the alkylsilane-treated silica upon collision with silica in an external addition dam is obtained. By setting the ratio of the average primary particle diameter of strontium titanate particles to the average primary particle diameter of alkylsilane-treated silica particles to 2.0 or less, the collision frequency energy required to appropriately release cyclic siloxane from the alkylsilane-treated silica upon collision with silica in an external addition dam can be satisfied.

[0083] -Method for Measuring Average Primary Particle Diameter- Hereinafter, methods for measuring the average primary particle diameter of alkylsilane-treated silica particles and the average primary particle diameter of strontium titanate particles are described.

[0084] · Method for Measuring Average Primary Particle Diameter of Alkylsilane-Treated Silica Particles A toner containing alkylsilane-treated silica particles is imaged at a magnification of 40,000 times using a scanning electron microscope (SEM) (S-4800, manufactured by Hitachi High-Technologies Corporation) equipped with an energy dispersive X-ray spectrometer (EDX apparatus) (EMAX Evolution X-Max80mm, manufactured by Horiba Ltd. 2 ). By EDX analysis, 300 or more primary silica particles are identified from within one field of view based on the presence of Si. SEM observation is performed at an accelerating voltage of 15 kV, an emission current of 20 μA, and a WD of 15 mm, and EDX analysis is performed under the same conditions with a detection time of 60 minutes. The identified silica particles are analyzed with image processing analysis software WinRoof (Mitani Corporation), the equivalent circle diameter, area, and perimeter of each primary particle image are obtained, and circularity = 4π × (area) ÷ (perimeter)2 is further obtained. In the distribution of equivalent circle diameters, the equivalent circle diameter corresponding to a cumulative 50% from the small diameter side is taken as the average primary particle diameter.

[0085] · Method for Measuring Average Primary Particle Diameter of Strontium Titanate Particles In this embodiment, the primary particle size of the strontium titanate particles is the diameter of a circle having the same area as the primary particle image of the strontium titanate particles (so-called equivalent circle diameter), and the average primary particle size of the strontium titanate particles is the particle size that accounts for 50% of the cumulative distribution from the smallest diameter side in the number-based distribution of the primary particle sizes of the strontium titanate particles. The average primary particle size of the strontium titanate particles is determined by image analysis of at least 300 strontium titanate particles B.

[0086] Toner containing strontium titanate particles will be imaged at 40,000x magnification using a scanning electron microscope (SEM) (Hitachi High-Technologies Corporation, S-4800) equipped with an energy-dispersive X-ray analyzer (EDX analyzer) (Horiba, Ltd., EMAX Evolution X-Max 80mm²). EDX analysis will identify more than 300 primary strontium titanate particles based on the presence of Sr. The SEM will be observed under acceleration voltage of 15kV, emission current of 20μA, and WD15mm, while the EDX analysis will be performed under the same conditions with a detection time of 60 minutes. The identified strontium titanate particles were analyzed using the image processing software WinRoof (Mitani Corporation) to determine the equivalent circle diameter, area, and perimeter of each primary particle image. Furthermore, the circularity was calculated as 4π × (area) ÷ (perimeter)². The average primary particle size was then defined as the equivalent circle diameter at which the cumulative 50% of the distribution of equivalent circle diameters from the smallest diameter side occurred.

[0087] (Content ratio of alkylsilane-treated silica particles and strontium titanate particles) The ratio of strontium titanate particles to silica particles (strontium titanate particle content / silica particle content) is preferably 0.01 to 1.0, more preferably 0.02 to 0.9, and even more preferably 0.03 to 0.8.

[0088] By setting the strontium titanate particle content to 0.01 to 1.0 relative to the silica particle content, cleaning defects of the image holder are further suppressed when high-density images are formed continuously and at high speed. The reason for this is presumed to be as follows. By setting the content of strontium titanate particles to 0.01 or more relative to the content of silica particles, the amount of strontium titanate particles in the external dam becomes appropriately high. This is thought to provide the necessary collision frequency for appropriately releasing cyclic siloxanes from alkylsilane-treated silica during collisions with silica in the external dam, thereby improving the effect of assisting in the appropriate and continuous release of cyclic siloxanes. By setting the content of strontium titanate particles to 1.0 or less relative to the silica particle content, the amount of strontium titanate particles in the external dam becomes appropriate. This allows for the collision frequency necessary to appropriately release cyclic siloxanes from alkylsilane-treated silica during collisions with silica in the external dam, thereby improving the effect of assisting in the appropriate and continuous release of cyclic siloxanes. The collision frequency with silica in the external dam does not become excessive, and cyclic siloxanes from alkylsilane-treated silica can be released appropriately and continuously without a large amount being released at once.

[0089] (Toner particles) Toner particles are composed of, for example, a binder resin, and optionally, a colorant, a release agent, and other additives.

[0090] -Binding resin- Examples of binder resins include vinyl resins consisting of monomers such as styrenes (e.g., styrene, parachlorostyrene, α-methylstyrene, etc.), (meth)acrylic acid esters (e.g., methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (e.g., acrylonitrile, methacrylonitrile, etc.), vinyl ethers (e.g., vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), and olefins (e.g., ethylene, propylene, butadiene, etc.), or copolymers of two or more of these monomers. Examples of binder resins include non-vinyl resins such as epoxy resins, polyester resins, polyurethane resins, polyamide resins, cellulose resins, polyether resins, and modified rosin; mixtures of these with the aforementioned vinyl resins; and graft polymers obtained by polymerizing vinyl monomers in the presence of these. These binding resins may be used individually or in combination of two or more types.

[0091] Polyester resin is preferred as the binder resin. Examples of polyester resins include well-known polyester resins.

[0092] Examples of polyester resins include condensation polymers of polycarboxylic acids and polyhydric alcohols. Commercially available polyester resins or synthesized polyester resins may be used.

[0093] Examples of polycarboxylic acids include aliphatic dicarboxylic acids (e.g., oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenylsuccinic acid, adipic acid, sebacic acid, etc.), alicyclic dicarboxylic acids (e.g., cyclohexanedicarboxylic acid, etc.), aromatic dicarboxylic acids (e.g., terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, etc.), their anhydrides, or their lower alkyl esters (e.g., with 1 to 5 carbon atoms). Among these, aromatic dicarboxylic acids are preferred as polycarboxylic acids. Polycarboxylic acids may be used in combination with dicarboxylic acids, or with trivalent or higher carboxylic acids that have a cross-linked or branched structure. Examples of trivalent or higher carboxylic acids include trimellitic acid, pyromellitic acid, their anhydrides, or their lower alkyl esters (e.g., having 1 to 5 carbon atoms). Polycarboxylic acids may be used individually or in combination of two or more.

[0094] Examples of polyhydric alcohols include aliphatic diols (e.g., ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (e.g., cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, etc.), and aromatic diols (e.g., ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, etc.). Among these, aromatic diols and alicyclic diols are preferred as polyhydric alcohols, and aromatic diols are more preferred. As for the polyhydric alcohol, a trihydric or higher polyhydric alcohol with a cross-linked or branched structure may be used in combination with the diol. Examples of trihydric or higher polyhydric alcohols include glycerin, trimethylolpropane, and pentaerythritol. Polyhydric alcohols may be used individually or in combination of two or more types.

[0095] The glass transition temperature (Tg) of the polyester resin is preferably 50°C to 80°C, and more preferably 50°C to 65°C. The glass transition temperature is determined from the DSC curve obtained by differential scanning calorimetry (DSC), and more specifically, it is determined by the "extracorporeal glass transition onset temperature" described in the method for determining the glass transition temperature in JIS K 7121-1987 "Method for Measuring the Transition Temperature of Plastics".

[0096] The weight-average molecular weight (Mw) of the polyester resin is preferably 5,000 to 1,000,000, and more preferably 7,000 to 500,000. The number-average molecular weight (Mn) of the polyester resin is preferably between 2,000 and 100,000. The molecular weight distribution (Mw / Mn) of the polyester resin is preferably 1.5 to 100, and more preferably 2 to 60. The weight-average molecular weight and number-average molecular weight are measured by gel permeation chromatography (GPC). GPC molecular weight measurement is performed using a Tosoh GPC-HLC-8120GPC analyzer, a Tosoh TSKgel SuperHM-M (15cm) column, and THF solvent. The weight-average molecular weight and number-average molecular weight are calculated from these measurement results using a molecular weight calibration curve prepared with monodisperse polystyrene standard samples.

[0097] Polyester resins can be obtained by well-known manufacturing methods. Specifically, for example, they can be obtained by a method in which the polymerization temperature is set to 180°C or higher and 230°C or lower, and the reaction system is subjected to reduced pressure as needed, while removing water and alcohol generated during condensation. If the monomers of the raw materials do not dissolve or become miscible at the reaction temperature, a high-boiling point solvent may be added as a solubilizer to dissolve them. In this case, the polycondensation reaction should be carried out while distilling off the solubilizer. If there are monomers with poor miscibility, it is advisable to condense the poorly miscible monomers with the acid or alcohol to be polycondensed with them beforehand, and then polycondense them together with the main component.

[0098] The binder resin content is preferably 40% to 95% by mass, more preferably 50% to 90% by mass, and even more preferably 60% to 85% by mass, relative to the total toner particles.

[0099] -Colorants- Examples of colorants include carbon black, chrome yellow, Hansa yellow, benzidine yellow, surene yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, balkan orange, Watch Young red, permanent red, brilliant carmine 3B, brilliant carmine 6B, DuPont oil red, pyrazolone red, risole red, rhodamine B lake, lake red C, pigment red, rose bengal, aniline blue, and ultramarine. Examples include various pigments such as phosphorus blue, chalcioyl blue, methylene blue chloride, phthalocyanine blue, pigment blue, phthalocyanine green, and malachite green oxalate, as well as various dyes such as acridine, xanthene, azo, benzoquinone, azine, anthraquinone, thioindico, dioxazine, thiazine, azomethine, indico, phthalocyanine, aniline black, polymethine, triphenylmethane, diphenylmethane, and thiazole. Colorants may be used individually or in combination of two or more types.

[0100] The coloring agent may be a surface-treated coloring agent as needed, and may be used in combination with a dispersant. Furthermore, multiple types of coloring agents may be used in combination.

[0101] The colorant content is preferably 1% to 30% by mass, and more preferably 3% to 15% by mass, relative to the total toner particles.

[0102] -Release agent- Examples of release agents include hydrocarbon waxes; natural waxes such as carnauba wax, rice wax, and candelilla wax; synthetic or mineral / petroleum-based waxes such as montan wax; and ester waxes such as fatty acid esters and montanic acid esters. However, the release agents are not limited to these.

[0103] The melting temperature of the release agent is preferably 50°C to 110°C, and more preferably 60°C to 100°C. The melting temperature is determined from the DSC curve obtained by differential scanning calorimetry (DSC) using the "melting peak temperature" described in JIS K 7121-1987 "Method for determining the transition temperature of plastics".

[0104] The release agent content is preferably 1% to 20% by mass, and more preferably 5% to 15% by mass, relative to the total toner particles.

[0105] -Other additives- Other additives include well-known additives such as magnetic materials, charge control agents, and inorganic powders. These additives are included in the toner particles as internal additives.

[0106] -Characteristics of toner particles, etc.- The toner particles may be single-layer toner particles, or they may be toner particles with a so-called core-shell structure, consisting of a core (core particle) and a coating layer (shell layer) that covers the core. Here, the core-shell structure of the toner particles may consist of, for example, a core portion comprising a binder resin and, if necessary, other additives such as a colorant and a release agent, and a coating layer comprising a binder resin.

[0107] The volume-average particle size (D50v) of the toner particles is preferably 2 μm or more and 10 μm or less, and more preferably 4 μm or more and 8 μm or less.

[0108] The average particle size and particle size distribution indices of the toner particles are measured using the Coulter Multisizer II (manufactured by Beckman Coulter), and the electrolyte is measured using the ISOTON-II (manufactured by Beckman Coulter). For measurement, add 0.5 mg to 50 mg of the sample to be measured in 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzenesulfonate) as a dispersant. Add this to 100 ml to 150 ml of electrolyte. The electrolyte containing the suspended sample is dispersed in an ultrasonic disperser for 1 minute. The particle size distribution of particles with a diameter of 2 μm to 60 μm is then measured using a Coulter Multisizer II with an aperture diameter of 100 μm. The number of particles sampled is 50,000. Based on the measured particle size distribution, a cumulative distribution of volume and number is drawn for each divided particle size range (channel) from the smallest diameter side. The particle size at which the cumulative total reaches 16% is defined as the volume particle size D16v and the number particle size D16p, the particle size at which the cumulative total reaches 50% is defined as the volume average particle size D50v and the cumulative number average particle size D50p, and the particle size at which the cumulative total reaches 84% ​​is defined as the volume particle size D84v and the number particle size D84p. Using these, the volume particle size distribution index (GSDv) is (D84v / D16v) 1 / 2 The GSDp index is (D84p / D16p) 1 / 2 It is calculated as follows.

[0109] The average circularity of the toner particles is preferably 0.94 to 1.00, and more preferably 0.95 to 0.98.

[0110] The average circularity of toner particles is determined by (circular equivalent perimeter) / (perimeter) [(perimeter of a circle with the same projected area as the particle image) / (perimeter of the particle projection image)]. Specifically, it is a value measured by the following method. First, the toner particles to be measured are collected by suction, a flattened flow is formed, and a still image of the particles is captured by instantaneous strobe flashing. This particle image is then analyzed using a flow-type particle image analyzer (FPIA-3000 manufactured by Sysmex Corporation). The number of samples used to determine the average circularity is 3500. If the toner contains external additives, the toner (developer) to be measured is dispersed in water containing a surfactant, and then ultrasonic treatment is performed to obtain toner particles from which the external additives have been removed.

[0111] (External additive) The toner according to this embodiment may also contain inorganic particles other than alkylsilane-treated silica particles and strontium titanate particles as external additives. Examples of such inorganic particles include TiO2, Al2O3, CuO, ZnO, SnO2, CeO2, Fe2O3, MgO, BaO, CaO, K2O, Na2O, ZrO2, CaO·SiO2, K2O·(TiO2)n, Al2O3·2SiO2, CaCO3, MgCO3, BaSO4, MgSO4, and the like.

[0112] The surface of the inorganic particles used as an external additive should preferably be hydrophobic. Hydrophobic treatment is carried out, for example, by immersing the inorganic particles in a hydrophobic agent. The hydrophobic agent is not particularly limited, but examples include silane-based coupling agents, silicone oil, titanate-based coupling agents, and aluminum-based coupling agents. These may be used individually or in combination of two or more. The amount of hydrophobic treatment agent is typically, for example, 1 to 10 parts by mass per 100 parts by mass of inorganic particles.

[0113] Examples of external additives include resin particles (such as polystyrene, polymethyl methacrylate (PMMA), and melamine resin), and cleaning activators (for example, metal salts of higher fatty acids represented by zinc stearate, and fluorine-based high molecular weight particles).

[0114] The amount of external additive used in combination with alkylsilane-treated silica particles is preferably 0% to 5% by mass, and more preferably 0% to 3% by mass, relative to the toner particles.

[0115] (Toner manufacturing method) Next, a description of the toner manufacturing method according to this embodiment will be given. The toner according to this embodiment is obtained by manufacturing toner particles and then adding alkylsilane-treated silica particles and, if necessary, strontium titanate particles to the toner particles.

[0116] Toner particles may be manufactured by either a dry process (e.g., kneading and grinding method) or a wet process (e.g., agglomeration, suspension polymerization, dissolution and suspension method). There are no particular restrictions on the manufacturing method of toner particles, and any well-known method may be used. Among these methods, obtaining toner particles by the aggregation and coalescence method is preferable.

[0117] Specifically, for example, when manufacturing toner particles by an aggregation and coalescence method, Toner particles are manufactured through the following steps: preparing a resin particle dispersion in which resin particles that will serve as a binder are dispersed (resin particle dispersion preparation step); a step of agglomerating resin particles (and other particles as needed) in the resin particle dispersion (and in a dispersion after mixing with other particle dispersions as needed) to form aggregated particles (aggregated particle formation step); and a step of heating the aggregated particle dispersion in which the aggregated particles are dispersed to fuse and combine the aggregated particles to form toner particles (fusion and combination step).

[0118] The details of each step are explained below. The following explanation describes a method for obtaining toner particles containing a colorant and a release agent, but the colorant and release agent are used only as needed. Of course, other additives besides colorants and release agents may also be used.

[0119] -Resin particle dispersion preparation process- First, a resin particle dispersion containing resin particles that will act as a binder is prepared, along with, for example, a coloring agent particle dispersion containing coloring agent particles and a release agent particle dispersion containing release agent particles.

[0120] Here, the resin particle dispersion is prepared, for example, by dispersing resin particles in a dispersion medium with a surfactant.

[0121] Examples of dispersion media used in resin particle dispersions include aqueous media. Examples of aqueous media include water such as distilled water and deionized water, and alcohols. These may be used individually or in combination of two or more.

[0122] Examples of surfactants include anionic surfactants such as sulfate esters, sulfonates, phosphates, and soaps; cationic surfactants such as amine salts and quaternary ammonium salts; and nonionic surfactants such as polyethylene glycol, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, anionic surfactants and cationic surfactants are particularly noteworthy. Nonionic surfactants may be used in combination with anionic or cationic surfactants. Surfactants may be used individually or in combination of two or more types.

[0123] In resin particle dispersions, common dispersion methods for dispersing resin particles in a dispersion medium include, for example, rotary shear homogenizers, ball mills with media, sand mills, and dyno mills. Depending on the type of resin particles, the resin particles may also be dispersed in the resin particle dispersion using, for example, a phase inversion emulsification method. Phase inversion emulsification is a method in which the resin to be dispersed is dissolved in a hydrophobic organic solvent in which the resin is soluble, a base is added to the organic continuous phase (O phase) to neutralize it, and then an aqueous medium (W phase) is added. This causes a conversion of the resin from W / O to O / W (so-called phase inversion), resulting in a discontinuous phase, and the resin is dispersed in the aqueous medium in particulate form.

[0124] The volume-average particle size of the resin particles dispersed in the resin particle dispersion is preferably 0.01 μm or more and 1 μm or less, more preferably 0.08 μm or more and 0.8 μm or less, and even more preferably 0.1 μm or more and 0.6 μm or less. The volume-average particle size of the resin particles is measured using a laser diffraction particle size distribution analyzer (e.g., LA-700, manufactured by Horiba, Ltd.). The particle size distribution is obtained by subtracting the cumulative distribution from the smallest particle size side for each divided particle size range (channel), and the particle size that accounts for 50% of the total particle size is measured as the volume-average particle size D50v. The volume-average particle size of particles in other dispersions is measured in the same manner.

[0125] The resin particle content in the resin particle dispersion is preferably, for example, 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 40% by mass or less.

[0126] Furthermore, colorant particle dispersions and release agent particle dispersions are prepared in the same manner as resin particle dispersions. In other words, the volume average particle size, dispersion medium, dispersion method, and particle content of the resin particle dispersions are the same for colorant particles dispersed in colorant particle dispersions and release agent particles dispersed in release agent particle dispersions.

[0127] -Agglomerated particle formation process- Next, the resin particle dispersion is mixed with the coloring agent particle dispersion and the mold release agent particle dispersion. Then, in the mixed dispersion, the resin particles, colorant particles, and release agent particles are heteroaggregated to form aggregated particles containing the resin particles, colorant particles, and release agent particles, which have a diameter close to the diameter of the target toner particles.

[0128] Specifically, for example, a coagulant is added to a mixed dispersion, the pH of the mixed dispersion is adjusted to be acidic (for example, pH 2 to 5), a dispersion stabilizer is added as needed, and then the mixture is heated to a temperature of the glass transition temperature of the resin particles (specifically, for example, above the glass transition temperature of the resin particles -30°C or below the glass transition temperature of -10°C) to agglomerate the particles dispersed in the mixed dispersion and form agglomerated particles. In the agglomerated particle formation step, for example, the mixed dispersion may be stirred in a rotary shear homogenizer, the above-mentioned flocculant may be added at room temperature (e.g., 25°C), the pH of the mixed dispersion may be adjusted to acidic (e.g., pH 2 to 5), a dispersion stabilizer may be added as needed, and then the above-mentioned heating may be performed.

[0129] Examples of flocculants include surfactants with opposite polarity to the surfactant used as a dispersant added to a mixed dispersion, inorganic metal salts, and metal complexes with a valency of 2 or higher. In particular, when a metal complex is used as a flocculant, the amount of surfactant used is reduced and the electrostatic properties are improved. Additives that form complexes or similar bonds with the metal ions of the flocculant may be used as needed. Chelating agents are preferably used as such additives.

[0130] Examples of inorganic metal salts include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate, as well as inorganic metal salt polymers such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. As a chelating agent, a water-soluble chelating agent may be used. Examples of chelating agents include oxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid, as well as iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), and ethylenediaminetetraacetic acid (EDTA). The amount of chelating agent to be added is preferably 0.01 parts by mass or more and 5.0 parts by mass or less per 100 parts by mass of resin particles, and more preferably 0.1 parts by mass or more and less than 3.0 parts by mass.

[0131] -Fusion / unification process- Next, the dispersion of aggregated particles is heated to a temperature above the glass transition temperature of the resin particles (for example, 10 to 30°C higher than the glass transition temperature of the resin particles) to fuse and combine the aggregated particles and form toner particles.

[0132] Toner particles are obtained through the above process. Furthermore, toner particles may be manufactured by further mixing a dispersion of aggregated particles containing dispersed aggregated particles with a dispersion of resin particles containing dispersed resin particles, thereby agglomerating the aggregated particles so that resin particles adhere to the surface of the aggregated particles to form second aggregated particles, and by heating the second dispersion of aggregated particles containing the second aggregated particles to fuse and combine the second aggregated particles to form toner particles with a core / shell structure.

[0133] After the fusion and combination process is complete, the toner particles formed in the solution are subjected to known washing, solid-liquid separation, and drying processes to obtain dried toner particles. The washing process should be thoroughly performed using ion-exchanged water for displacement washing, considering the electrostatic charge. The solid-liquid separation process is not particularly restricted, but suction filtration, pressure filtration, etc., are preferable for productivity. The drying process is also not particularly restricted, but freeze-drying, air-flow drying, fluidized bed drying, vibratory fluidized bed drying, etc., are preferable for productivity.

[0134] The toner according to this embodiment is manufactured, for example, by adding alkylsilane-treated silica particles and, if necessary, strontium titanate particles to the obtained dried toner particles and mixing them. Mixing can be performed using, for example, a V-blender, a Henschel mixer, a Redigge mixer, etc. Furthermore, if necessary, coarse particles of the toner may be removed using a vibrating screen separator, a wind screen separator, etc.

[0135] <Electrostatic Image Developer> The electrostatic image developer according to this embodiment includes at least the toner according to this embodiment. The electrostatic image developer according to this embodiment may be a one-component developer containing only the toner according to this embodiment, or it may be a two-component developer mixed with the toner and a carrier.

[0136] There are no particular restrictions on the carriers, and known carriers can be used. Examples of carriers include coated carriers in which a coating resin is applied to the surface of a core material made of magnetic powder; magnetic powder dispersed carriers in which magnetic powder is dispersed and blended in a matrix resin; and resin-impregnated carriers in which resin is impregnated into porous magnetic powder. Furthermore, magnetic powder dispersed carriers and resin-impregnated carriers may be carriers in which the constituent particles of the carrier are used as a core material and coated with a coating resin.

[0137] Examples of magnetic powders include magnetic metals such as iron, nickel, and cobalt, and magnetic oxides such as ferrite and magnetite.

[0138] Examples of coating resins and matrix resins include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic acid ester copolymer, straight silicone resin or modified thereof containing organosiloxane bonds, fluororesin, polyester, polycarbonate, phenolic resin, epoxy resin, and the like. Furthermore, the coating resin and matrix resin may contain conductive particles or other additives. Examples of conductive particles include metals such as gold, silver, and copper, as well as carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

[0139] To coat the surface of the core material with a coating resin, one method is to coat it with a coating layer-forming solution in which the coating resin and, if necessary, various additives are dissolved in a suitable solvent. The solvent is not particularly limited and should be selected considering the coating resin used, its suitability for coating, etc. Specific resin coating methods include the immersion method, in which the core material is immersed in a coating layer forming solution; the spray method, in which the coating layer forming solution is sprayed onto the surface of the core material; the fluidized bed method, in which the coating layer forming solution is sprayed onto the core material while it is suspended by fluidized air; and the kneader coater method, in which the carrier core material and the coating layer forming solution are mixed in a kneader coater and the solvent is removed.

[0140] In a two-component developer, the mixing ratio (mass ratio) of toner and carrier is preferably toner:carrier = 1:100 to 30:100, and more preferably 3:100 to 20:100.

[0141] <Image forming device / image forming method> An image forming apparatus / image forming method according to this embodiment will be described. The image forming apparatus according to this embodiment comprises an image holder, a charging means for charging the surface of the image holder, an electrostatic image forming means for forming an electrostatic image on the charged surface of the image holder, a developing means for containing an electrostatic image developer and developing the electrostatic image formed on the surface of the image holder as a toner image using the electrostatic image developer, a transfer means for transferring the toner image formed on the surface of the image holder to the surface of a recording medium, and a fixing means for fixing the toner image transferred to the surface of the recording medium. The electrostatic image developer according to this embodiment is applied as the electrostatic image developer.

[0142] The image forming apparatus according to this embodiment implements an image forming method (image forming method according to this embodiment) comprising: a charging step of charging the surface of an image holder; an electrostatic image forming step of forming an electrostatic image on the charged surface of the image holder; a developing step of developing the electrostatic image formed on the surface of the image holder as a toner image using an electrostatic image developer according to this embodiment; a transfer step of transferring the toner image formed on the surface of the image holder to the surface of a recording medium; and a fixing step of fixing the toner image transferred to the surface of the recording medium.

[0143] The image forming apparatus according to this embodiment may be a direct transfer type apparatus that directly transfers a toner image formed on the surface of an image holder to a recording medium; an intermediate transfer type apparatus that first transfers a toner image formed on the surface of an image holder to the surface of an intermediate transfer body, and secondarily transfers the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium; an apparatus equipped with cleaning means for cleaning the surface of the image holder before charging after the transfer of the toner image; or an apparatus equipped with static elimination means for irradiating the surface of the image holder with static elimination light before charging after the transfer of the toner image. In the case of an intermediate transfer method apparatus, the transfer means may include, for example, an intermediate transfer body on which a toner image is transferred; a primary transfer means for primaryly transferring the toner image formed on the surface of the image holder to the surface of the intermediate transfer body; and a secondary transfer means for secondary transferring the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium.

[0144] In the image forming apparatus according to this embodiment, for example, the part including the developing means may be a cartridge structure (process cartridge) that can be attached to and detached from the image forming apparatus. As the process cartridge, for example, a process cartridge equipped with a developing means containing the electrostatic image developer according to this embodiment is preferably used.

[0145] The following is an example of an image forming apparatus according to this embodiment, but it is not limited to this example. The main parts shown in the figure will be described, and other parts will be omitted from the explanation.

[0146] Figure 1 is a schematic diagram showing the image forming apparatus according to this embodiment. The image forming apparatus shown in Figure 1 is equipped with first to fourth electrophotographic image forming units 10Y, 10M, 10C, and 10K (image forming means) that output images of yellow (Y), magenta (M), cyan (C), and black (K) based on color-separated image data. These image forming units (hereinafter sometimes simply referred to as "units") 10Y, 10M, 10C, and 10K are arranged side by side at predetermined distances from each other in the horizontal direction. These units 10Y, 10M, 10C, and 10K may also be process cartridges that can be attached to and detached from the image forming apparatus.

[0147] In the drawings of each unit 10Y, 10M, 10C, and 10K, an intermediate transfer belt 20 is extended through each unit as an intermediate transfer body. The intermediate transfer belt 20 is wound around drive rolls 22 and support rolls 24 that are spaced apart from each other from left to right in the drawing and are in contact with the inner surface of the intermediate transfer belt 20, and is configured to travel in the direction from the first unit 10Y to the fourth unit 10K. The support rolls 24 are subjected to a force that moves away from the drive rolls 22 by a spring or the like (not shown), and tension is applied to the intermediate transfer belt 20 wound around both. In addition, an intermediate transfer body cleaning device 30 is provided on the side of the image holder of the intermediate transfer belt 20, facing the drive rolls 22. Furthermore, each of the developing devices (developing means) 4Y, 4M, 4C, and 4K for each unit 10Y, 10M, 10C, and 10K is supplied with toner containing four colors of toner: yellow, magenta, cyan, and black, contained in toner cartridges 8Y, 8M, 8C, and 8K.

[0148] Since the first to fourth units 10Y, 10M, 10C, and 10K have equivalent configurations, the first unit 10Y, which forms the yellow image and is located on the upstream side in the direction of travel of the intermediate transfer belt, will be described as a representative example. The descriptions of the second to fourth units 10M, 10C, and 10K will be omitted by assigning reference numerals to parts equivalent to the first unit 10Y, with magenta (M), cyan (C), and black (K) instead of yellow (Y).

[0149] The first unit 10Y has a photoreceptor 1Y that acts as an image holder. Around the photoreceptor 1Y are, in order, a charging roll (an example of a charging means) 2Y that charges the surface of the photoreceptor 1Y to a predetermined potential, an exposure device (an example of a charge image forming means) 3 that exposes the charged surface with a laser beam 3Y based on a color-separated image signal to form a charge image, a developing device (an example of a developing means) 4Y that supplies charged toner to the charge image to develop the charge image, a primary transfer roll 5Y (an example of a primary transfer means) that transfers the developed toner image onto an intermediate transfer belt 20, and a photoreceptor cleaning device (an example of a cleaning means) 6Y that removes toner remaining on the surface of the photoreceptor 1Y after primary transfer. The primary transfer roll 5Y is positioned inside the intermediate transfer belt 20, facing the photoreceptor 1Y. Furthermore, each of the primary transfer rolls 5Y, 5M, 5C, and 5K is connected to a bias power supply (not shown) that applies a primary transfer bias. Each bias power supply varies the transfer bias applied to each primary transfer roll through control by a control unit (not shown).

[0150] The following describes the process of forming the yellow image in the first unit 10Y. First, prior to operation, the surface of the photoreceptor 1Y is charged to a potential of -600V to -800V by the charging roll 2Y. The photoreceptor 1Y is conductive (e.g., volume resistivity at 20°C: 1 × 10⁻⁶). -6The photosensitive layer is formed by laminating a photosensitive layer on a substrate (less than Ωcm). This photosensitive layer normally has high resistance (resistance of general resin), but when irradiated with a laser beam 3Y, the resistivity of the irradiated area changes. Therefore, a laser beam 3Y is output to the surface of the charged photoreceptor 1Y via the exposure device 3 according to image data for yellow sent from a control unit (not shown). The laser beam 3Y irradiates the photosensitive layer on the surface of the photoreceptor 1Y, thereby forming an electrostatic image of the yellow image pattern on the surface of the photoreceptor 1Y.

[0151] A static charge image is an image formed on the surface of a photoreceptor 1Y due to charging. It is a so-called negative latent image formed when the resistivity of the irradiated portion of the photoreceptor layer decreases due to the laser beam 3Y, causing the charged material on the surface of the photoreceptor 1Y to flow, while the charge remains in the portion not irradiated by the laser beam 3Y. The electrostatic charge image formed on the photoreceptor 1Y is rotated to a predetermined development position as the photoreceptor 1Y moves. At this development position, the electrostatic charge image on the photoreceptor 1Y is made visible as a toner image (developed image) by the developing device 4Y.

[0152] The developing device 4Y contains, for example, an electrostatic image developer including at least yellow toner and a carrier. The yellow toner is triboelectrically charged by being agitated inside the developing device 4Y and is held on the developer roll (an example of a developer holder) with a charge of the same polarity (negative polarity) as the static charge on the photoreceptor 1Y. As the surface of the photoreceptor 1Y passes through the developing device 4Y, the yellow toner electrostatically adheres to the discharged latent image on the surface of the photoreceptor 1Y, and the latent image is developed by the yellow toner. The photoreceptor 1Y, on which the yellow toner image has been formed, continues to move at a predetermined speed, and the toner image developed on the photoreceptor 1Y is transported to a predetermined primary transfer position.

[0153] When the yellow toner image on the photoreceptor 1Y is transported to the primary transfer, a primary transfer bias is applied to the primary transfer roll 5Y, and an electrostatic force from the photoreceptor 1Y toward the primary transfer roll 5Y acts on the toner image, transferring the toner image on the photoreceptor 1Y onto the intermediate transfer belt 20. The transfer bias applied at this time has a polarity opposite to the toner's polarity (-) (+), and in the first unit 10Y, for example, it is controlled to +10 μA by a control unit (not shown). Meanwhile, any toner remaining on the photoreceptor 1Y is removed and recovered by the photoreceptor cleaning device 6Y.

[0154] Furthermore, the primary transfer bias applied to the primary transfer rolls 5M, 5C, and 5K of the second unit from 10M onward is also controlled in accordance with the first unit. Thus, the intermediate transfer belt 20, on which the yellow toner image has been transferred in the first unit 10Y, is sequentially transported through the second to fourth units 10M, 10C, and 10K, and the toner images of each color are superimposed and transferred in multiple layers.

[0155] The intermediate transfer belt 20, on which four-color toner images have been multiple-transferred through the first to fourth units, proceeds to a secondary transfer section composed of the intermediate transfer belt 20, a support roll 24 in contact with the inner surface of the intermediate transfer belt, and a secondary transfer roll (an example of a secondary transfer means) 26 positioned on the image-holding surface side of the intermediate transfer belt 20. Meanwhile, recording paper (an example of a recording medium) P is fed via a supply mechanism into the gap between the secondary transfer roll 26 and the intermediate transfer belt 20 at a predetermined timing, and a secondary transfer bias is applied to the support roll 24. The transfer bias applied at this time has the same polarity (-) as the toner's polarity (-), and an electrostatic force from the intermediate transfer belt 20 toward the recording paper P acts on the toner image, transferring the toner image on the intermediate transfer belt 20 onto the recording paper P. The secondary transfer bias at this time is determined according to the resistance detected by a resistance detection means (not shown) that detects the resistance of the secondary transfer section, and is voltage-controlled.

[0156] After this, the recording paper P is fed to the contact area (nip area) of a pair of fixing rolls in a fixing device (an example of fixing means) 28, where the toner image is fixed onto the recording paper P, and a fixed image is formed.

[0157] Examples of recording paper P used to transfer toner images include plain paper used in electrophotographic photocopiers and printers. Other recording media besides recording paper P include OHP sheets. To further improve the smoothness of the image surface after fixing, it is preferable that the surface of the recording paper P is also smooth. For example, coated paper, which is plain paper coated with resin or the like, or art paper for printing are preferably used.

[0158] Once the color image has been fixed onto the recording paper P, it is discharged towards the output section, and the series of color image formation operations is completed.

[0159] <Processor Cartridges / Toner Cartridges> The process cartridge according to this embodiment will be described. The process cartridge according to this embodiment contains the electrostatic image developer according to this embodiment and includes a developing means for developing the electrostatic image formed on the surface of the image holder as a toner image using the electrostatic image developer, and is a process cartridge that can be attached to and detached from an image forming apparatus.

[0160] The process cartridge according to this embodiment is not limited to the above configuration, and may also include a developing device and, as necessary, at least one other means selected from, for example, an image holder, a charging means, an electrostatic image forming means, and a transfer means.

[0161] The following shows an example of a process cartridge according to this embodiment, but it is not limited to this example. The main parts shown in the figure will be described, and other parts will not be explained.

[0162] Figure 2 is a schematic diagram showing the process cartridge according to this embodiment. The process cartridge 200 shown in Figure 2 is constructed by integrally holding a photoreceptor 107 (an example of an image holder), a charging roll 108 (an example of a charging means) provided around the photoreceptor 107, a developing device 111 (an example of a developing means), and a photoreceptor cleaning device 113 (an example of a cleaning means) within a housing 117 equipped with a mounting rail 116 and an opening 118 for exposure, and is then formed into a cartridge. In Figure 2, 109 represents an exposure apparatus (an example of electrostatic image formation means), 112 represents a transfer apparatus (an example of a transfer means), 115 represents a fixing apparatus (an example of a fixing means), and 300 represents recording paper (an example of a recording medium).

[0163] Next, the toner cartridge according to this embodiment will be described. The toner cartridge according to this embodiment is a toner cartridge that contains the toner according to this embodiment and is attached to and detached from an image forming apparatus. The toner cartridge contains replenishment toner for supply to a developing means provided within the image forming apparatus.

[0164] The image forming apparatus shown in Figure 1 is an image forming apparatus with removable toner cartridges 8Y, 8M, 8C, and 8K. The developing units 4Y, 4M, 4C, and 4K are connected to toner cartridges corresponding to each developing unit (color) by toner supply pipes (not shown). When the toner contained in a toner cartridge becomes low, the toner cartridge is replaced. [Examples]

[0165] Examples are described below, but the present invention is not limited to these examples. In the following description, unless otherwise specified, "parts" and "%" all refer to mass.

[0166] <Production of toner particles> [Preparation of amorphous polyester resin dispersion (A1)] • Ethylene glycol: 37 parts • Neopentyl glycol: 65 parts • 1,9-nonanediol: 32 parts Terephthalic acid: 96 parts The above materials were placed in a reaction vessel, and the temperature was raised to 200°C over 1 hour. After confirming that the reaction system was uniformly stirred, 1.2 parts of dibutyltin oxide were added. The temperature was raised to 240°C over 6 hours while distilling off the generated water, and stirring was continued at 240°C for 4 hours to obtain amorphous polyester resin (acid value 9.4 mg KOH / g, weight-average molecular weight 13,000, glass transition temperature 62°C). The amorphous polyester resin, in its molten state, was transferred to an emulsifier / disperser (Cavitron CD1010, Eurotech) at a rate of 100 g per minute. Separately, 0.37% dilute ammonia water, obtained by diluting reagent ammonia water with deionized water, was placed in a tank and transferred to the emulsifier / disperser simultaneously with the amorphous polyester resin at a rate of 0.1 liters per minute while being heated to 120°C in a heat exchanger. The emulsifier / disperser was operated at a rotor speed of 60 Hz and a pressure of 5 kg / cm². 2 The system was operated under the specified conditions to obtain an amorphous polyester resin dispersion (A1) with a volume-average particle size of 160 nm and a solid content of 20%.

[0167] [Preparation of crystalline polyester resin dispersion (C1)] Decandioic acid: 81 parts • Hexanediol: 47 parts The above materials were placed in a reaction vessel, and the temperature was raised to 160°C over 1 hour. After confirming that the reaction system was uniformly stirred, 0.03 parts of dibutyltin oxide were added. The temperature was raised to 200°C over 6 hours while distilling off the water produced, and stirring was continued at 200°C for 4 hours. Next, the reaction mixture was cooled, solid-liquid separation was performed, and the solid was dried at 40°C under reduced pressure to obtain crystalline polyester resin (C1) (melting point 64°C, weight-average molecular weight 15,000).

[0168] Crystalline polyester resin (C1): 50 parts • Anionic surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Neogen RK): 2 parts • Ion-exchanged water: 200 bottles The above materials were heated to 120°C and thoroughly dispersed in a homogenizer (Ultra-Turrax T50, IKA Corporation), followed by dispersion treatment in a pressure-discharge homogenizer. When the volume-average particle size reached 180 nm, the mixture was collected to obtain a crystalline polyester resin dispersion (C1) with a solid content of 20%.

[0169] [Preparation of mold release agent particle dispersion (W1)] • Paraffin wax (HNP-9, manufactured by Nippon Seiro Co., Ltd.): 100 units • Anionic surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Neogen RK): 1 part • Ion-exchanged water: 350 units The above materials were mixed and heated to 100°C, dispersed using a homogenizer (IKA Ultra-Turrax T50), and then dispersed again using a pressure-discharge type Gorin homogenizer to obtain a release agent particle dispersion containing release agent particles with a volume-average particle size of 200 nm. Deionized water was added to this release agent particle dispersion to adjust the solid content to 20%, resulting in release agent particle dispersion (W1).

[0170] [Preparation of colorant particle dispersion (C1)] • Cyan pigment (pigment blue 15:3, Dainichi Seika Kogyo): 50 units • Anionic surfactant (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., Neogen RK): 5 parts • Ion-exchanged water: 195 units The above materials were mixed and dispersed for 60 minutes using a high-pressure impact disperser (Ultimizer HJP30006, Sugino Machine Co., Ltd.) to obtain a colorant particle dispersion (C1) with a solid content of 20%.

[0171] [Production of toner particles] • Ion-exchanged water: 200 bottles • Amorphous polyester resin dispersion (A1): 150 parts • Crystalline polyester resin dispersion (C1): 10 parts • Release agent particle dispersion (W1): 10 parts • Coloring agent particle dispersion (C1): 15 parts • Anionic surfactant (TaycaPower): 2.8 parts The above materials were placed in a reaction vessel, and 0.1N nitric acid was added to adjust the pH to 3.5. Then, an aqueous solution of aluminum chloride (Oji Paper Co., Ltd., 30% powder) was added, which was prepared by dissolving 2 parts of aluminum chloride in 30 parts of deionized water. The mixture was dispersed at 30°C using a homogenizer (IKA Ultra-Turrax T50), and then heated in a heating oil bath to 45°C, where it was held until the volume-average particle size reached 4.9 μm. Next, 60 parts of amorphous polyester resin dispersion (A1) were added and held for 30 minutes. When the volume-average particle size reached 5.2 μm, another 60 parts of amorphous polyester resin dispersion (A1) were added and held for 30 minutes. Subsequently, 20 parts of a 10% NTA (nitrilotriacetic acid) metal salt aqueous solution (Kirest 70, Kirest Co., Ltd.) were added, and a 1N sodium hydroxide aqueous solution was added to adjust the pH to 9.0. Next, 1 part of anionic surfactant (TaycaPower) was added, and the mixture was heated to 85°C while continuing to stir, and held for 5 hours. Then, it was cooled to 20°C at a rate of 20°C / min. Finally, the mixture was filtered, thoroughly washed with deionized water, and dried to obtain toner particles with a volume-average particle size of 5.7 μm and an average circularity of 0.971.

[0172] <Preparation of alkylsilane-treated silica particles> (Alkylsilane-treated silica particles (S1)) - Fabrication of silica matrix particles - 255 parts methanol and 33 parts 10% aqueous ammonia were added to a 1.5 L glass reaction vessel equipped with a stirrer, dropping nozzle, and thermometer, and mixed to obtain a mixture. After adjusting this mixture to 25°C, 153 parts tetramethoxysilane and 49 parts 3.8% aqueous ammonia were added simultaneously while stirring, and the addition was carried out dropwise over 60 minutes to obtain 420 parts of hydrophilic silica particle dispersion. Subsequently, 420 parts of methanol were added to the hydrophilic silica particle dispersion, and the mixture was heated at 60°C with stirring until the dispersion was concentrated to a mass of 420 parts. This process was repeated two more times to obtain a concentrated dispersion. The silica weight ratio in the concentrated dispersion was adjusted to 50%, and the weight ratio of water to alcohol in the concentrated dispersion was 0, thereby obtaining a silica mother particle dispersion.

[0173] -Alkylsilane treatment- The silica dispersion was subjected to solvent removal treatment and alkylsilane treatment as shown below. An autoclave with a stirrer (capacity 500 ml) and a back pressure valve was prepared, and 400 parts of the silica mother particle dispersion were poured into the autoclave. The autoclave was then filled with liquefied carbon dioxide. Next, the stirrer was operated at 200 rpm, the temperature was raised to 150°C using a heater, and then the pressure was increased to 20 MPa using a carbon dioxide pump. This circulated supercritical carbon dioxide within the autoclave, removing the solvent from the silica mother particle dispersion. A trap device was maintained at 0°C using a refrigerant, allowing for the separation of the removed solvent from the carbon dioxide. The carbon dioxide flow rate was measured using a gas flow meter. Next, when the amount of supercritical carbon dioxide flowed (cumulative value: measured as the amount of carbon dioxide flowing under standard conditions) reached 20 L, the flow of supercritical carbon dioxide was stopped. Then, trimethylmethoxysilane was added as an alkylsilane so that the surface treatment amount of alkylsilane on the alkylsilane-treated silica particles was 30% by mass. Subsequently, dodecamethylcyclohexanesiloxane was added as a cyclic siloxane so that the cyclic siloxane content relative to the total mass of the alkylsilane-treated silica particles was 120 ppm. Subsequently, the temperature was maintained at 150°C using a heater and the pressure at 20 MPa using a carbon dioxide pump, maintaining a supercritical state of carbon dioxide in the autoclave. The agitator was operated at 200 rpm, and the mixture was held for 30 minutes as a hydrophobic treatment time. After 30 minutes, supercritical carbon dioxide was circulated again, and the pressure was released to atmospheric pressure through the back pressure valve, allowing it to cool to room temperature. After that, the alkylsilane-treated silica particles (S1) were removed from the autoclave.

[0174] (Alkylsilane-treated silica particles (S2)~(S15)) Alkylsilane-treated silica particles were obtained using the same procedure as for alkylsilane-treated silica particles (S1), except that the types of alkylsilane and cyclic siloxane were as shown in Table 1, the amount of alkylsilane added was adjusted so that the surface treatment amount of alkylsilane on the alkylsilane-treated silica particles was as shown in Table 1, and the amount of cyclic siloxane added was adjusted so that the content of cyclic siloxane relative to the total mass of the alkylsilane-treated silica particles was as shown in Table 1.

[0175] [Table 1]

[0176] (Alkylsilane-treated silica particles (S16)~(S24)) In the preparation of silica matrix particles, alkylsilane-treated silica particles were obtained using the same procedure as for alkylsilane-treated silica particles (S2), except that the amount of 3.8% aqueous ammonia added and the amount of tetramethoxysilane (indicated as "TMOS" in Table 2) added were changed as shown in Table 2.

[0177] [Table 2]

[0178] <Production of strontium titanate particles> (Strontium titanate particles (1)) 0.7 moles of metatitanic acid, the desulfurized and gelatinized titanium source, were taken as TiO2 and placed in a reaction vessel. Next, 0.77 moles of strontium chloride aqueous solution were added to the reaction vessel so that the SrO / TiO2 molar ratio was 1.1. Then, a solution of lanthanum oxide dissolved in nitric acid was added to the reaction vessel in an amount such that 2.5 moles of lanthanum were added for every 100 moles of strontium. The initial TiO2 concentration in the mixture of the three materials was adjusted to 0.75 moles / L. Next, the mixture was stirred, heated to 90°C, and while maintaining the temperature at 90°C and stirring, 153 mL of 10N sodium hydroxide aqueous solution was added over 0.7 hours, and stirring was continued for 1 hour while maintaining the temperature at 90°C. Next, the reaction mixture was cooled to 40°C, and hydrochloric acid was added until the pH reached 5.5, and stirring was carried out for 1 hour. Finally, the precipitate was washed by repeated decantation and redispersion in water. Hydrochloric acid was added to the slurry containing the washed precipitate to adjust the pH to 6.5, and solid-liquid separation was performed by filtration, and the solid was dried. An ethanol solution of i-butyltrimethoxysilane was added to the dried solid in an amount of 20 parts i-butyltrimethoxysilane per 100 parts solid, and the mixture was stirred for 1 hour. Solid-liquid separation was performed by filtration, and the solid was dried in air at 130°C for 7 hours to obtain strontium titanate particles (1).

[0179] (Strontium titanate particles (2)) Strontium titanate particles (2) were prepared in the same manner as strontium titanate particles (1), except that the time for adding the 10N sodium hydroxide solution dropwise was changed to 1 hour.

[0180] (Strontium titanate particles (3)) Strontium titanate particles (3) were prepared in the same manner as strontium titanate particles (1), except that the time for adding the 10N sodium hydroxide solution dropwise was changed to 3 hours.

[0181] (Strontium titanate particles (4)) Strontium titanate particles (4) were prepared in the same manner as strontium titanate particles (1), except that the time for adding the 10N sodium hydroxide solution dropwise was changed to 9.5 hours.

[0182] (Strontium titanate particles (5)) Strontium titanate particles (5) were prepared in the same manner as for strontium titanate particles (1), except that the time for adding the 10N sodium hydroxide solution dropwise was changed to 12 hours.

[0183] (Strontium titanate particles (6)) Strontium titanate particles (6) were prepared in the same manner as for the preparation of strontium titanate particles (1), except that the time for adding the 10N sodium hydroxide aqueous solution dropwise was changed to 15 hours.

[0184] <Example 1: Preparation of toner and developer> Toner was obtained by adding 2 parts alkylsilane-treated silica particles (S1) to 100 parts toner particles and mixing them in a Henschel mixer at a peripheral speed of 30 m / sec for 15 minutes.

[0185] Then, the obtained toners and the resin-coated carriers described below were placed in a V-blender in a toner:carrier ratio of 8:92 (by mass) and stirred for 20 minutes to obtain a developer.

[0186] -Career- Mn-Mg-Sr ferrite particles (average particle size 40 μm): 100 parts • Toluene: 14 parts • Polymethyl methacrylate: 2 parts • Carbon Black (VXC72: Cabot): 0.12 parts Mix the above materials, excluding ferrite particles, with glass beads (1 mm in diameter, in the same amount as toluene). The mixture was then stirred for 30 minutes at a rotation speed of 1200 rpm using a sand mill manufactured by Kansai Paint Co., Ltd. to obtain a dispersion. This dispersion and ferrite particles were placed in a vacuum-degassed kneader and dried under reduced pressure while stirring to obtain a resin-coated carrier.

[0187] <Examples 2-29, Comparative Example 1> Toner and developer were obtained using the same procedure as in Example 1, except that the type and amount of alkylsilane-treated silica particles and the type and amount of strontium titanate particles added to the toner particles were changed as shown in Table 3. When preparing toner containing strontium titanate particles, the strontium titanate particles were added to the toner particles along with alkylsilane-treated silica particles during toner preparation and mixed in a Henschel mixer.

[0188] <Rating> In a DCC400 image forming apparatus (manufactured by Fujifilm Business Innovation Co., Ltd.) with the density sensor disabled, the developer obtained in each example was loaded, and 10 A3 images with solid color (100% image density) were printed under conditions of 10°C and 15% RH. Subsequently, blank pages (0% image density) were printed repeatedly, for a total of 100,000 blank pages. Next, one blank page was printed, and the number of streaky stains that appeared on that blank page was checked and evaluated according to the evaluation criteria below. -Evaluation Criteria- G1: The number of streaky stains is less than 5. G1.5: The number of streaky stains is 5 or more but less than 10. G2: The number of streaky stains is 10 or more but less than 20. G2.5: The number of streaky stains is 20 or more but less than 30. G3: The number of streaky stains is 30 or more but less than 50. G3.5: The number of streaky stains is 50 or more but less than 70. G4: The number of streaky stains is 70 or more but less than 90. G4.5: The number of streaky stains is 90 or more but less than 110. G5: There are 110 or more streaky stains.

[0189] [Table 3-1]

[0190] [Table 3-2]

[0191] [Table 3-3]

[0192] Descriptions of the entries in Table 3 are provided below. • Abbreviations for the type of alkylsilane and the type of cyclic siloxane: have the same meanings as those in Table 1. • "Content (%) relative to silica particles" described in the lower column for cyclic siloxane: means the content of cyclic siloxane relative to the total alkylsilane-treated silica particles. • Ratio (amount of CSi / amount of AlSi): means the ratio of the content of cyclic siloxane to the surface treatment amount of alkylsilane (content of cyclic siloxane / surface treatment amount of alkylsilane). • SrTiO₃ particle size / SiO₂ particle size: the average primary particle size of strontium titanate particles relative to the average primary particle size of silica particles (average primary particle size of strontium titanate particles / average primary particle size of silica particles) • SrTiO₃ amount / SiO₂ amount: the content of strontium titanate particles relative to the content of silica particles (content of strontium titanate particles / content of silica particles)

[0193] From the above results, it can be seen that the toner of the present example suppresses poor cleaning of the image bearing member when forming continuous, high-speed images with high image density.

[0194] (((1))) alkylsilane-treated silica particles, a cyclic siloxane, and toner particles; a toner for developing electrostatic images comprising the foregoing. The toner for developing electrostatic images according to (((1))), wherein (((2))) the alkylsilane is at least one selected from the group consisting of alkylsilanes represented by the following formula (1), the following formula (2) and the following formula (3).

[0195]

Chemical Formula

[0196] (In formulas (1) to (3), R1 to R 12 each independently represent an alkyl group having 1 to 3 carbon atoms.) The toner for developing electrostatic images according to (((2))), wherein (((3))) all alkyl groups of the alkylsilane are methyl groups. The toner for developing electrostatic images according to any one of (((1))) to (((3))), wherein (((4))) the number of siloxane units constituting the cyclic structure of the cyclic siloxane is 3 or more and 6 or less. The toner for developing electrostatic images according to (((4))), wherein (((5))) the cyclic siloxane having 3 or more and 6 or less siloxane units has a methyl group. The toner for developing electrostatic images according to any one of (((1))) to (((5))), wherein (((6))) the content of the cyclic siloxane is 10 ppm or more and 1000 ppm or less based on a total amount of the silica particles. The toner for developing electrostatic images according to any one of (((1))) to (((6))), wherein (((7))) a ratio of the content of the cyclic siloxane to a surface treatment amount of the alkylsilane (content of cyclic siloxane / surface treatment amount of alkylsilane) is 0.0001 or more and 0.01 or less. The toner for developing electrostatic images according to any one of (((1))) to (((7))), wherein (((8))) the cyclic siloxane is contained in silica particles. The toner for developing electrostatic images according to any one of (((1))) to (((8))), comprising strontium titanate particles having an average primary particle diameter of 10 nm or more and 100 nm or less, wherein (((9))). (((10))) The toner for developing electrostatic images according to (((9))), wherein the average primary particle size of the strontium titanate particles (average primary particle size of strontium titanate particles / average primary particle size of silica particles) is 0.01 or more and 2.0 or less. (((11))) The toner for developing electrostatic images according to (((9))) or (((10))), wherein the content of strontium titanate particles (content of strontium titanate particles / content of silica particles) relative to the content of silica particles is 0.01 or more and 1.0 or less. A electrostatic image developer containing the toner for electrostatic image development described in any one of (((12))) (((1))) to (((11))). (((13))) (((1))) to (((11))) contain the electrostatic image developing toner described in any one of the above, A toner cartridge that is attached to and detached from an image forming machine. (((14))) (((12))) The developing means contains the electrostatic image developer described in (((14))) and develops the electrostatic image formed on the surface of the image holder as a toner image using the electrostatic image developer, A process cartridge that is attached to and detached from an image forming apparatus. (((15))) Image holder and, A charging means for charging the surface of the image holder, A means for forming an electrostatic image on the surface of the charged image holder, A developing means containing the electrostatic image developer described in (((12))) and developing the electrostatic image formed on the surface of the image holder as a toner image using the electrostatic image developer, A transfer means for transferring a toner image formed on the surface of the image holder to the surface of a recording medium, Fixing means for fixing the toner image transferred to the surface of the recording medium, An image forming apparatus equipped with the following features.

[0197] According to the invention of (((1))) or (((2))), an electrostatic image developing toner is provided which includes alkylsilane-treated silica particles and toner particles, and which suppresses cleaning defects of the image holder when a high-density image is formed continuously and at high speed, compared to the case in which a cyclic siloxane is not included. According to the invention of (((3))), an electrostatic image developing toner is provided that suppresses cleaning defects of the image holder when a high-density image is formed continuously and at high speed, compared to the case where the alkylsilane is triethylmethoxysilane. According to the invention of (((4))), an electrostatic image developing toner is provided that suppresses cleaning defects of the image holder when a high-density image is formed continuously and at high speed, compared to the case where the number of siloxane units constituting the cyclic structure of the cyclic siloxane exceeds 6. According to the invention of (((5))), an electrostatic image developing toner is provided that suppresses cleaning defects of the image holder when a high-density image is formed continuously and at high speed, compared to the case in which a cyclic siloxane having 3 to 6 siloxane units has an ethyl group.

[0198] According to the invention of (((6))), an electrostatic image developing toner is provided that suppresses cleaning defects of the image holder when a high-density image is formed continuously and at high speed, compared to the case where the content of the cyclic siloxane is less than 10 ppm or more than 1000 ppm relative to the total silica particles. According to the invention of (((7))), an electrostatic image developing toner is provided that suppresses cleaning defects of the image holder when a high-density image is formed continuously and at high speed, compared to the case where the ratio of the content of the cyclic siloxane to the amount of surface treatment of the alkylsilane (content of cyclic siloxane / amount of surface treatment of alkylsilane) is less than 0.0001 or greater than 0.01. According to the invention of (((8))), an electrostatic image developing toner is provided that suppresses cleaning defects of the image holder when a high-density image is formed continuously and at high speed, compared to the case in which cyclic siloxane is included in a particle other than silica particles. According to the invention of (((9))), an electrostatic image developing toner is provided that suppresses cleaning defects of the image holder when a high-density image is formed continuously and at high speed, compared to the case in which strontium titanate particles with an average primary particle size of less than 10 nm are included or the case in which strontium titanate particles with an average primary particle size of more than 100 nm are included. According to the invention of (((10))), an electrostatic image developing toner is provided that suppresses cleaning defects of the image holder when a high-density image is formed continuously and at high speed, compared to the case where the average primary particle size of the strontium titanate particles (average primary particle size of strontium titanate particles / average primary particle size of silica particles) is less than 0.01 or greater than 2.0 with respect to the average primary particle size of the silica particles.

[0199] According to the invention of (((11))), an electrostatic image developing toner is provided that suppresses cleaning defects of the image holder when a high-density image is formed continuously and at high speed, compared to the case where the content of strontium titanate particles (content of strontium titanate particles / content of silica particles) relative to the content of silica particles is less than 0.01 or greater than 1.0. According to the inventions of (((12))), (((13))), (((14))), or (((15))), an electrostatic image developer, toner cartridge, process cartridge, or image forming apparatus is provided, which includes an electrostatic image developer toner comprising alkylsilane-treated silica particles and toner particles, which suppresses cleaning defects of the image holder when forming high-density images continuously and at high speed, compared to the case in which an electrostatic image developer toner without cyclic siloxane is included. [Explanation of symbols]

[0200] 1Y, 1M, 1C, 1K photoreceptors (examples of image retainers) 2Y, 2M, 2C, 2K Charging rolls (an example of charging means) 3 Exposure device (an example of electrostatic charge image forming means) 3Y, 3M, 3C, 3K Laser beams 4Y, 4M, 4C, 4K Developing devices (an example of developing means) 5Y, 5M, 5C, 5K Primary transfer rolls (an example of primary transfer means) 6Y, 6M, 6C, 6K Photoreceptor cleaning devices (an example of cleaning means) 8Y, 8M, 8C, 8K Toner cartridges 10Y, 10M, 10C, 10K Image forming units 20 Intermediate transfer belt (an example of intermediate transfer member) 22 Driving roll 24 Support roll 26 Secondary transfer roll (an example of secondary transfer means) 30 Intermediate transfer member cleaning device 107 Photoreceptor (an example of image holding member) 108 Charging roll (an example of charging means) 109 Exposure device (an example of electrostatic charge image forming means) 111 Developing device (an example of developing means) 112 Transfer device (an example of transfer means) 113 Photoreceptor cleaning device (an example of cleaning means) 115 Fixing device (an example of fixing means) 116 Mounting rail 118 Opening for exposure 117 Housing 200 Process cartridge 300 Recording paper (an example of recording medium) P Recording paper (an example of recording medium)

Claims

1. Alkylsilane-treated silica particles and Cyclic siloxanes and Toner particles, and, The alkylsilane is at least one selected from the group consisting of alkylsilanes represented by the following formulas (1), (2), and (3): The cyclic siloxane has at least one selected from the group consisting of a methyl group, an ethyl group, and a propyl group. The cyclic siloxane is a toner for developing electrostatic images, contained in the alkylsilane-treated silica particles. 【Chemistry 1】 (In formulas (1) to (3), R1 to R12 each independently represent an alkyl group having 1 to 3 carbon atoms.)

2. The electrostatic image developing toner according to claim 1, wherein R1 to R12 in formulas (1) to (3) are methyl groups.

3. The electrostatic image developing toner according to claim 1, wherein the siloxane units constituting the cyclic structure of the cyclic siloxane are 3 to 6.

4. The toner for developing electrostatic images according to claim 3, wherein the cyclic siloxane having 3 to 6 siloxane units has a methyl group.

5. The toner for developing electrostatic images according to claim 1, wherein the content of the cyclic siloxane is 10 ppm or more and 1000 ppm or less relative to the total amount of silica particles.

6. The toner for developing electrostatic images according to claim 1, wherein the ratio of the content of the cyclic siloxane to the amount of surface treatment of the alkylsilane (content of cyclic siloxane / amount of surface treatment of alkylsilane) is 0.0001 or more and 0.01 or less.

7. The toner for developing electrostatic images according to claim 1, comprising strontium titanate particles having an average primary particle size of 10 nm or more and 100 nm or less.

8. The toner for developing electrostatic images according to claim 7, wherein the average primary particle size of the strontium titanate particles (average primary particle size of strontium titanate particles / average primary particle size of silica particles) is 0.01 or more and 2.0 or less, relative to the average primary particle size of the silica particles.

9. The electrostatic image developing toner according to claim 7, wherein the content of strontium titanate particles relative to the content of silica particles (content of strontium titanate particles / content of silica particles) is 0.01 or more and 1.0 or less.

10. A electrostatic image developer comprising the electrostatic image developing toner according to any one of claims 1 to 9.

11. A toner for electrostatic image development according to any one of claims 1 to 9 is contained, A toner cartridge that is attached to and detached from an image forming machine.

12. The development means comprises a static charge image developer according to claim 10, and develops a static charge image formed on the surface of an image holder as a toner image using the static charge image developer, A process cartridge that is attached to and detached from an image forming apparatus.

13. Image holder and, A charging means for charging the surface of the image holder, A means for forming an electrostatic image on the surface of the charged image holder, A developing means comprising: containing the electrostatic image developer described in claim 10; and developing the electrostatic image formed on the surface of the image holder as a toner image using the electrostatic image developer; A transfer means for transferring a toner image formed on the surface of the image holder to the surface of a recording medium, Fixing means for fixing the toner image transferred to the surface of the recording medium, An image forming apparatus equipped with the following features.

Images