Toner and image forming method

Abstract

To provide a toner excellent in suppression of an external clinging additive ghost while suppressing scratches to a photoreceptor and toner fusion.SOLUTION: A toner includes toner particles and an external additive including silica fine particles subjected to surface treatment and titanic acid compound particles on the surfaces of the toner particles. The DD / MAS measurement of solid 29 Si-NMR of the silica particles observes a peak PD1 corresponding to a silicon atom in the D1 structure of a siloxane chain and a peak PD2 corresponding to a silicon atom in the D2 structure of the siloxane chain; when setting the area of the peak PD1 to SD1 and the area of the peak PD2 to SD2, SD1 and SD2 satisfy 1.2≤(SD1+SD2) / SD1≤10.0; the number average particle size of the primary particles of the titanic acid compound fine particles is 10 nm or more and 100 nm or less; and the average circularity of the primary particles of the titanic acid compound fine particles is 0.700 or more and 1.00 or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a toner used in electrophotography, electrostatic recording, electrostatic printing and the like, and an image forming method. [Background Art]

[0002] In recent years, full-color copiers employing electrophotography have been widely popularized, and their application to the printing market has begun. In the printing market, high image quality and high stability are increasingly required along with higher speed. To achieve higher image quality, it is necessary to stabilize the charging characteristics of toner. Various studies have been conducted on external additives to stabilize the charging characteristics of toners. For example, Patent Document 1 discloses a toner whose charging characteristics are improved by externally adding silica particles surface-treated with cyclic siloxane. Patent Document 2 discloses a toner whose charging stability is improved by externally adding strontium titanate in which the number-average particle diameter of primary particles is 10 nm or more and 95 nm or less, and the half-width of the diffraction angle in X-ray diffraction has a specific value. On the other hand, for high stability, a cleaning step of removing toner and external additives remaining on the photoreceptor without being transferred is important. When the toner on the photoreceptor is exposed to high temperatures, the toner fuses to the photoreceptor and causes image defects. In addition, part of the external additives externally added to the toner detaches and adheres to the photoreceptor. Patent Document 3 discloses a toner in which, by externally adding lanthanum-doped titanate compound particles, advantage is taken of the fact that the rounded titanate compound particles detach onto the photoreceptor, thereby improving the effect of polishing the toner and external additives adhering to the photoreceptor without damaging the photoreceptor in the cleaning step. [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2016-167029 [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2022-22414 [Patent Document 3] Japanese Patent Publication No. 2022-34384 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] However, with increasing speed, it has been found that using external additives with small particle size and round shape, such as those described in Patent Documents 2 and 3, can sometimes result in image inconsistencies. The following is considered to be the cause of image unevenness: When images with clearly separated image and non-image areas are output consecutively, differences occur in the amount of external additive that slips through the cleaning process and travels around on the photoreceptor. It has been found that when a halftone image is output in this state, image unevenness (hereinafter also referred to as external additive-carrying ghosting) may occur. External additive-related ghosting is an image defect that occurs when external additives, which detach from the toner and adhere to the photoreceptor, are not removed during the cleaning process and instead travel around on the photoreceptor. Blade cleaning is preferred for the photoreceptor cleaning process. When cleaning the photoreceptor with a blade, the angle and pressure at which the blade is pressed against the photoreceptor are important. If the pressure is too weak, the toner and external additives cannot be removed by the cleaning nip, and conversely, if the pressure is too high, the blade will vibrate, causing the toner and external additives to slip through. By setting the blade to the appropriate angle and pressure, it is possible to remove the toner and external additives, but as the particle size of the external additives becomes smaller and their shape becomes rounder, removal in the cleaning process becomes more difficult, and the amount that slips through increases. Further improvements to the toner were essential to suppress damage to the photoreceptor and toner fusion, while also suppressing ghosting caused by external additives. [Means for solving the problem]

[0005] The present invention relates to a toner having toner particles and an external additive on the surface of the toner particles, The external additive comprises silica microparticles and titanate compound microparticles. The silica nanoparticles are surface-treated silica nanoparticles, Solid silica fine particles 29 In DD / MAS measurements of Si-NMR, the Si in the structure represented by the following formula (1) a Peak PD1 corresponds to the silicon atom shown, and Si in the structure represented by the following formula (2). b A peak PD2 corresponding to the silicon atom shown is observed, and when the area of ​​peak PD1 is taken as SD1 and the area of ​​peak PD2 is taken as SD2, then SD1 and SD2 are 1.2 ≤ (SD1 + SD2) / SD1 ≤ 10.0 Satisfying the conditions, The number-average particle size of the primary particles of the titanate compound fine particles is 10 nm or more and 100 nm or less. The present invention relates to a toner characterized in that the average circularity of the primary particles of the titanate compound fine particles is 0.700 or more and 1.00 or less.

[0006] [ka] (In formulas (1) and (2), R independently represents a hydrogen atom, a methyl group, or an ethyl group.) Furthermore, the present invention relates to an image forming method comprising: a charging step of charging the surface of a photoreceptor; an electrostatic latent image forming step of forming an electrostatic latent image on the charged photoreceptor; a developing step of developing the electrostatic latent image with toner to form a toner image on the surface of the photoreceptor; a transfer step of transferring the toner image to a recording medium; a fixing step of fixing the toner image on the recording medium; and a cleaning step of contacting the photoreceptor with a cleaning blade to remove residual toner on the photoreceptor, The present invention relates to an image forming method characterized in that the toner is a toner having the above-described configuration. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a toner that suppresses scratches on the photoreceptor and toner fusion, while also effectively suppressing ghosting caused by external additives. The same effect can also be achieved by the image forming method of the present invention. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram illustrates the diameter a of the silica microparticles and the area b in which the silica microparticles are embedded, which are necessary for calculating the embedding rate of silica microparticles on the surface of toner particles. [Figure 2] This is a schematic diagram of a heat treatment apparatus suitable for surface-treating toner particles mixed with external silica microparticles using hot air. [Modes for carrying out the invention]

[0009] In this invention, unless otherwise specified, the descriptions of a numerical range, such as "greater than or equal to XX and less than or equal to XX" or "XX to XX," mean a numerical range that includes the lower and upper limits, which are the endpoints.

[0010] [Features of the present invention] The inventors of the present invention investigated toners that could achieve high image quality and high stability even at higher speeds. As a result, they found that by using a toner with silica fine particles and a titanate compound having the configuration of the present invention as external additives, scratches on the photoreceptor and toner fusion are suppressed over a long period of time, while ghosting caused by the external additives is effectively suppressed.

[0011] We believe the reasons for the effectiveness of this invention are as follows.

[0012] In order to suppress scratches on the photoreceptor and toner fusion, it is necessary to add titanate compound fine particles externally, with the number-average particle size of the primary particles of the titanate compound fine particles being between 10 nm and 100 nm, and the average circularity of the primary particles of the titanate compound fine particles being between 0.700 and 1.00.

[0013] The number-average particle size of the primary particles of the titanate compound fine particles is between 10 nm and 100 nm. This allows them to detach from the toner and adhere uniformly to the photoreceptor surface, resulting in a good polishing effect on the photoreceptor surface and preventing toner fusion to the photoreceptor.

[0014] Furthermore, an average circularity of 0.700 or higher for primary particles means that the titanate compound has a round shape, which suppresses scratching of the photoreceptor and exhibits a better polishing effect, thus preventing toner fusion to the photoreceptor.

[0015] However, when an external additive with a number-average particle size of 100 nm or less and a round shape detaches from the toner and adheres to the photoreceptor, it becomes difficult to remove during the cleaning process, resulting in a large amount of pass-through. Furthermore, when images with clearly separated image and non-image areas are output continuously, the image area contains a large amount of titanate compound fine particles detached from the toner, and the amount of pass-through is also large, causing ghosting that is associated with the external additive.

[0016] The inventors of the present invention conducted intensive studies to suppress ghosting of external additives and found that by using the titanate compound fine particles as an external additive together with silica fine particles having the structure of the present invention, the amount of external additive components that pass through is suppressed, resulting in good suppression of ghosting of external additives.

[0017] The silica nanoparticles of the present invention are surface-treated silica nanoparticles, and are solid 29 In DD / MAS measurements of Si-NMR, the Si in the structure represented by the following formula (1) a Peak PD1 corresponds to the silicon atom shown, and Si in the structure represented by the following formula (2). b A peak PD2 corresponding to the silicon atom shown is observed, and when the area of ​​peak PD1 is taken as SD1 and the area of ​​peak PD2 is taken as SD2, then SD1 and SD2 are 1.2 ≤ (SD1 + SD2) / SD1 ≤ 10.0 It is characterized by satisfying the following conditions.

[0018] [ka] (In formulas (1) and (2), R independently represents a hydrogen atom, a methyl group, or an ethyl group.)

[0019] The reason why ghosting due to external additives is effectively suppressed when using the silica microparticles of the present invention is thought to be because the silica microparticles firmly form a layer of silica microparticles and titanate compound microparticles on the nip portion of the cleaning blade.

[0020] As a result, we believe that the amount of silica and titanate compound microparticles that pass through was reduced, improving the suppression of ghosting caused by external additive penetration. Furthermore, by the titanate compound microparticles remaining in the external additive layer, the polishing effect on the photoreceptor was more effectively exhibited, resulting in better suppression of toner fusion to the photoreceptor.

[0021] The reason why the silica nanoparticles strongly formed a layer of silica nanoparticles and titanate compound nanoparticles is not clear, but it is thought to be as follows.

[0022] The silica nanoparticles are surface-treated silica nanoparticles characterized by having siloxane chains represented by formulas (1) and (2). The siloxane chains are solid. 29 In Si-NMR DD / MAS measurements, the D1 unit structure can be distinguished from the D2 unit structure shown in equation (1) and equation (2). Since the D1 unit structure represents the terminal group of the surface-treated molecule, 1.2 ≤ (SD1 + SD2) / SD1 ≤ 10.0 in this invention is an indicator of the length of the siloxane chain.

[0023] For a layer of silica microparticles to be firmly formed in the cleaning nip area, it is thought that the silica microparticles must be compacted in a form close to a close-packed structure, and that the silica must have high adhesion.

[0024] The silica nanoparticles of the present invention have a D1 unit structure at the end of the siloxane chain. Since the D1 unit structure has a polar group OR (R = hydrogen atom, methyl group, or ethyl group) at its end, it is thought that when compacted, the attractive force originating from the polar group acts strongly. In order to utilize the attractive force originating from the polar group, a certain length of siloxane chain is necessary for molecular mobility due to its stereochemistry, but if the siloxane chain is too long, the frequency of contact with the polar group decreases.

[0025] In the silica fine particles of the present invention, by controlling the length of the siloxane chain so as to satisfy 1.2≦(SD1+SD2) / SD1≦10.0, a strong layer can be formed in the cleaning nip portion due to the attractive force of the silica fine particles when consolidated.

[0026] (SD1+SD2) / SD1 is preferably 1.2 or more and 6.3 or less, more preferably 1.2 or more and 3.8 or less. When (SD1+SD2) / SD1 is within the above range, the contact frequency with polar groups increases, and a stronger layer can be formed.

[0027] The value of (SD1+SD2) / SD1 can be adjusted by changing the type of surface treatment agent containing a siloxane bond, or changing the temperature and time of the surface treatment, etc.

[0028] Furthermore, on the surface of the silica fine particle substrate, there are siloxane chains chemically bonded to the silica fine particle substrate, and it is preferable that such siloxane chains are sufficiently present.

[0029] The abundance of siloxane chains can be expressed as follows using the results of solid 29 Si-NMR DD / MAS measurement. In the solid 29 Si-NMR DD / MAS measurement, for Si in the structure represented by the following formula (3) c a peak PQ corresponding to the silicon atom indicated is observed, and when the area of the peak PQ is defined as SQ, the abundance (Ca) of the siloxane chain is given by the following formula (a) using SD1, SD2, and SQ. Ca=(SD1+SD2) / SQ×100 (a)

[0030]

Chemical Formula

[0031] The silica fine particles preferably have a Ca content of 1.0 or higher. More preferably, the Ca content is 4.0 or higher, and even more preferably 5.0 or higher. Considering that this is a surface treatment, the upper limit of the amount present is 30.0 or less for Ca.

[0032] Note that "Si in the structure represented by formula (3)" c The silicon atoms shown in the equation are what are known as Q-unit silicon atoms, and equation (a) above represents the ratio of the amount of D-unit silicon atoms to the amount of Q-unit silicon atoms. The silicon atoms in the silica nanoparticle substrate have a Q-unit structure, and there are almost no D-unit silicon atoms. Therefore, the D-unit silicon atoms are thought to originate from the surface treatment agent, and the above ratio represents the amount of siloxane chains that originate from the surface treatment.

[0033] The chemical bonding of siloxane chains to the surface of silica nanoparticles can be verified by washing the silica nanoparticles with a solvent (e.g., hexane) and confirming that the amount of the treatment agent changes little before and after washing.

[0034] The specific verification method is as follows:

[0035] 1.0 g of silica microparticles is weighed into a 50 ml screw-cap tube, and 20 ml of n-hexane is added. Then, the sample is extracted for 10 minutes at an intensity of 20 (output 10 W) using an ultrasonic homogenizer (TAITEC VP-050). The resulting extract is separated using a centrifuge, the supernatant is removed, and the n-hexane is removed from the resulting wet sample using an evaporator to obtain silica microparticles after hexane washing.

[0036] Using silica nanoparticles washed with hexane, solid 29 Si-NMR DD / MAS measurements were performed, and the Si in the structure represented by equation (1) a The area SD1w of the peak PD1w corresponding to the silicon atom shown, and the Si in the structure represented by equation (2). bThe area SD2w of the peak PD2w corresponding to the silicon atom shown, and the Si in the structure represented by equation (3) c The area SQw of the peak PQw corresponding to the silicon atom shown is obtained. Using the obtained areas SD1w, SD2w, and SQw, the amount of siloxane chain (Cb) after hexane washing is calculated from the following equation (b). Cb = (SD1w + SD2w) / SQw × 100 (b)

[0037] Using the above values ​​of Ca and Cb, and the following formula (c1), we determine the rate of decrease ΔC in the amount of siloxane chain after hexane washing compared to before hexane washing. ΔC(%) = (Ca - Cb) / Ca × 100 (c1)

[0038] This reduction rate ΔC is considered to be the ratio of the amount of siloxane chains not chemically bonded to the surface of the silica nanoparticles to the amount of siloxane chains present on the surface of the silica nanoparticle substrate, and in the present invention, it is preferably 30% or less. That is, Ca and Cb satisfy the following formula (c). (Ca-Cb) / Ca×100 ≤ 30 (c)

[0039] Furthermore, the reduction rate ΔC is preferably 0% or more and 20% or less, more preferably 0% or more and 5.0% or less, and even more preferably 0% or more and 1.0% or less.

[0040] When measuring the physical properties of the silica microparticles described above, if it is necessary to separate the silica microparticles from the toner particles, the measurements can be taken after separation using the method described later. In the separation method described later, separation is performed in an aqueous medium, so no elution of silicon compounds into the medium occurs. As a result, the silica microparticles can be separated from the toner particles while maintaining the physical properties of the silica microparticles before the separation process. Therefore, the values ​​of each physical property measured using the silica microparticles separated from the toner particles will be substantially the same as the values ​​of each physical property measured using the silica microparticles before external addition.

[0041] (Method for separating silica microparticles from toner particles) Weigh 20g of a 10% aqueous solution of "Contaminon N" (a pH 7 neutral detergent for cleaning precision measuring instruments consisting of a nonionic surfactant, anionic surfactant, and organic builder) into a 50mL vial and mix with 1g of toner.

[0042] The toner is placed in an Iwaki Sangyo Co., Ltd. "KM Shaker" (model: V.SX), and the speed is set to 50 and shaken for 30 seconds. This causes the silica microparticles to migrate from the surface of the toner particles to the aqueous solution. Then, in the case of magnetic toner containing magnetic material, the toner particles are restrained using a neodymium magnet, and the silica microparticles that have migrated to the supernatant are separated. The settled toner is then dried under vacuum (40°C / 24 hours) to obtain silica microparticles.

[0043] In the case of non-magnetic toner, the toner and the silica particles that have migrated to the supernatant liquid are separated using a centrifuge (H-9R; manufactured by Kokusan Co., Ltd.) (at 1000 rpm for 5 minutes).

[0044] Furthermore, if external additives other than silica microparticles are added to the toner, the silica microparticles and other external additives can be separated by centrifugal separation of the external additives separated from the toner using the method described above. Even if multiple types of silica microparticles are added to the toner, separation is possible by centrifugal separation as long as they have different particle size ranges. For example, separation can be performed using a CS120FNX (manufactured by Hitachi Koki Co., Ltd.) at 40,000 rpm for 20 minutes.

[0045] (solid 29 (Method for measuring SiNMR) solid 29 The specific measurement conditions for Si-NMR are as follows: Equipment: JNM-ECA400 (JEOL RESONANCE) Calibration: TMS (tetramethylsilane) to 0 ppm Temperature: room temperature Measurement method: DD / MAS method 29 Si 45° Sample tube: Zirconia 8.0 mmφ Sample: A test tube filled with silica microparticles in powder form. Sample rotation speed: 6kHz Relaxation delay: 90 seconds Scan: 5640

[0046] In the NMR spectrum obtained by the above-described measurement, the peak corresponding to the siloxane chain appearing around -20 ppm is separated to obtain peak PD1 corresponding to silicon atoms with a D1 unit structure and peak PD2 corresponding to silicon atoms with a D2 unit structure. From these peaks, the peak areas SD1 and SD2 are determined. Peak separation is performed using the following procedure.

[0047] (Peak separation method) Peak separation is performed by analyzing the NMR spectrum data obtained using the method described above. Peak separation can be performed using commercially available software or a program created in-house, following the procedure described below.

[0048] The peak positions are fixed at -18.2 ppm for peak PD1 and -21.0 ppm for peak PD2, and peak separation is performed using the Voigt function.

[0049] Silica nanoparticles are thought to have the structure shown in equation (4) below. In equation (4), the leftmost silicon atom (Q unit structure) is silicon from the silica nanoparticle substrate, and the parts that bond to it (D1 unit structure, D2 unit structure) are parts (siloxane chains) derived from the surface treatment agent chemically bonded to the surface of the silica nanoparticle substrate. The value of n in equation (4) is not specified, but considering that (SD1 + SD2) / SD1 is between 1.2 and 3.8 and WD2 is between 0.1 ppm and 6.0 ppm, it is presumed that n=1 or 2 is at the center of the distribution of n values, and that the distribution of n values ​​is within the range of n=0 to 5.

[0050] [ka] (In the formula, R independently represents a hydrogen atom, a methyl group, or an ethyl group, and n is an integer of 0 or greater (preferably between 0 and 5).)

[0051] [Silica microparticles] The silica nanoparticles in this invention will be described below.

[0052] It is preferable that the silica nanoparticles have a compound having a siloxane structure on their surface. Furthermore, it is preferable to obtain them by treating the surface of a silica nanoparticle substrate with a surface treatment agent containing siloxane bonds. In other words, it is preferable that the silica nanoparticles are products treated with a surface treatment agent containing siloxane bonds.

[0053] In this invention, when silica nanoparticles are surface-treated with a surface treatment agent containing siloxane bonds, the portion derived from the surface treatment agent is also referred to as silica nanoparticles. Silica nanoparticles before surface treatment are sometimes referred to as "silica nanoparticle substrates."

[0054] The surface treatment agent containing siloxane bonds is not particularly limited, and known materials can be used. To easily obtain the above physical properties, it is preferable to perform a surface treatment on the silica fine particle substrate.

[0055] Surface treatment agents containing siloxane bonds include, for example, silicone oils such as dimethyl silicone oil; silicone oils in which the side chains or terminals of dimethyl silicone oil are modified with organic groups, such as methyl hydrogen silicone oil, methylphenyl silicone oil, alkyl-modified silicone oil, chloroalkyl-modified silicone oil, chlorophenyl-modified silicone oil, fatty acid-modified silicone oil, polyether-modified silicone oil, alkoxy-modified silicone oil, carbinol-modified silicone oil, amino-modified silicone oil, and fluorine-modified silicone oil; and cyclic siloxanes such as hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane.

[0056] The surface treatment agent containing siloxane bonds is preferably a cyclic siloxane. More preferably, it is a cyclic siloxane with up to 10 membered rings. The cyclic siloxane may have substituents on some of the methyl groups bonded to the silicon atoms. Among the cyclic siloxanes, it is preferable that it be at least one selected from the group consisting of hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, and decamethylcyclopentasiloxane. From the viewpoint of ease of controlling (SD1+SD2) / SD1 and ease of purification, it is more preferable to include octamethylcyclotetrasiloxane.

[0057] The method for surface treatment of the silica microparticle substrate is not particularly limited and can be carried out by contacting the silica microparticle substrate with a surface treatment agent containing siloxane bonds. From the viewpoint of uniformly treating the surface of the silica microparticle substrate and easily achieving the above physical properties, it is preferable to contact the silica microparticle substrate with the surface treatment agent in a dry manner. As will be described later, examples of methods include contacting the silica microparticle substrate with the vapor of the surface treatment agent, or spraying the undiluted solution of the surface treatment agent or a diluted solution with various solvents into contact with the silica microparticle substrate.

[0058] The processing temperature is not particularly limited, as it varies depending on the reactivity of the surface treatment agent used. It is preferable to mix the silica fine particle substrate and the surface treatment agent and heat-treat them at a temperature of 300°C or higher. More preferably, it is 310°C to 380°C.

[0059] The processing time varies depending on the processing temperature and the reactivity of the surface treatment agent used, but is preferably 5 minutes to 300 minutes, more preferably 30 minutes to 240 minutes, and even more preferably 60 minutes to 200 minutes. The above-mentioned processing temperature and processing time are preferable from the viewpoint of allowing the treatment agent to react sufficiently with the silica fine particle substrate, as well as from the viewpoints of ease of control of (SD1+SD2) / SD1 and production efficiency.

[0060] For contact between the surface treatment agent and the silica microparticle substrate, it is preferable to contact the surface treatment agent vapor under reduced pressure or in an inert gas atmosphere such as a nitrogen atmosphere. Using the vapor contact method makes it easier to remove surface treatment agents that do not react with the silica microparticle surface. When using the vapor contact method, it is preferable to perform the treatment at a treatment temperature above the boiling point of the surface treatment agent. The vapor contact may be carried out in multiple steps (for example, 2 to 3 times).

[0061] The silica nanoparticles are obtained by treating a silica nanoparticle substrate with a cyclic siloxane, and it is more preferable that the treatment is carried out at a treatment temperature of 300°C or higher.

[0062] Since cyclic siloxanes react with the OSiOH groups on the surface of silica nanoparticle substrates via ring-opening reactions, a D1 unit structure can be effectively obtained, and the (SD1+SD2) / SD1 ratio can be easily controlled.

[0063] On the other hand, silicon atoms with terminal D1 unit structures that are generated during ring opening tend to become reaction sites with other cyclic siloxanes, leading to longer chain lengths. However, at a processing temperature of 300°C or higher, both the formation and cleavage of siloxane bonds occur. As a result, the siloxane chain becomes shorter and more uniform, and the value of (SD1+SD2) / SD1 falls within a predetermined range.

[0064] When using cyclic siloxane as a surface treatment agent, the amount of surface treatment agent is preferably 40 to 150 parts by mass, and more preferably 70 to 140 parts by mass, per 100 parts by mass of silica fine particle substrate. In particular, when surface treatment is performed by contacting the cyclic siloxane with vapor, it is preferable to add 70 parts by mass or more, and more preferably 100 parts by mass or more, per 100 parts by mass of silica fine particle substrate. This allows for more uniform surface treatment of the silica fine particle substrate and enables control of the amount of siloxane chain present (Ca) to 1.0 or higher.

[0065] Furthermore, when performing surface treatment under reduced pressure, it is preferable that the pressure due to the vapor of the surface treatment agent in the container be between 0.1 Pa and 100.0 Pa, and more preferably between 1.0 Pa and 10.0 Pa. By maintaining this pressure range, the frequency of contact between the vapor molecules of the surface treatment agent is reduced, suppressing chemical reactions between the surface treatment agents and allowing the chemical reaction between the surface treatment agent in contact with the surface of the silica microparticle substrate to proceed preferentially.

[0066] Furthermore, reaction byproducts generated by the chemical reaction between the silica microparticle substrate and the surface treatment agent can be easily removed from the vicinity of the silica microparticle surface, allowing the surface treatment agent to come into closer contact with the surface of the silica microparticle substrate, and enabling more uniform surface treatment of the silica microparticle substrate.

[0067] Furthermore, when performing surface treatment under reduced pressure, it is preferable to perform a degassing treatment by heating the silica microparticle substrate under reduced pressure to remove moisture and other substances adsorbed on the surface of the silica microparticle substrate before bringing the surface treatment agent into contact with the surface of the silica microparticle substrate. This makes it easier for the surface treatment agent to come into contact with the surface of the silica microparticle substrate, allowing for more uniform surface treatment of the silica microparticle substrate. In addition, from the viewpoint of making it easier for the surface treatment agent to come into contact with the surface of the silica microparticle substrate, it is also preferable to repeat the degassing treatment and the surface treatment of the silica microparticles with the surface treatment agent.

[0068] When using silicone oil as a surface treatment agent, the amount of the surface treatment agent is preferably 3 to 25 parts by mass, and more preferably 5 to 20 parts by mass, per 100 parts by mass of silica fine particle substrate. By using the above amount, the surface of the silica fine particles can be treated uniformly.

[0069] The kinematic viscosity of silicone oil at a temperature of 25°C is 30 mm, in terms of uniformly treating the surface of silica microparticles. 2 / s or more 500mm 2 Preferably less than / s, and 30mm 2 / s or more 200mm 2 / s or less is preferable.

[0070] By the method described above, it becomes possible to form siloxane chains on the surface of silica nanoparticles such that (SD1+SD2) / SD1 is between 1.2 and 10.0.

[0071] Furthermore, within the scope of satisfying the provisions of the present invention, after obtaining silica nanoparticles by the method described above, further treatment may be performed using the surface treatment agent containing the siloxane bond described above. The method of treatment is not particularly limited, and for example, it can be performed by bringing the surface treatment agent containing the siloxane bond into contact with the silica nanoparticles.

[0072] Silica nanoparticles are formed in which the hydrogen atoms of the silanol groups of the silica nanoparticle substrate are replaced by the siloxane chains described above, and they possess high hydrophobicity. The hydrophobicity of silica nanoparticles can be estimated by measuring the amount of moisture adsorbed by the silica nanoparticles. The silica nanoparticles have a BET specific surface area of ​​1 m² at a temperature of 30°C and a relative humidity of 80%. 2 The amount of water absorbed per unit is 0.010 cm³. 3 / m 2 More than 0.100cm 3 / m 2 Preferably, it is 0.020 cm. 3 / m 2 Above 0.070cm 3 / m 2 It is more preferable that it be less than 0.030 cm 3 / m 2 More than 0.060cm 3 / m 2 The following is even more preferable:

[0073] A method for manufacturing toner preferably includes the steps of preparing silica fine particles and mixing the silica fine particles with toner particles to obtain toner. Furthermore, a method for manufacturing toner preferably includes the step of preparing the silica fine particles obtained in the following steps.

[0074] The process for preparing silica nanoparticles preferably includes the steps of mixing a silica nanoparticle substrate with a surface treatment agent containing siloxane bonds (preferably a cyclic siloxane), performing a heat treatment at a temperature of 300°C or higher, and surface treating the surface of the silica nanoparticle substrate with the surface treatment agent containing siloxane bonds to prepare silica nanoparticles.

[0075] Examples of silica nanoparticle substrates include silicon compounds, particularly silicon halides, generally silicon chlorides, fumed silica typically produced by burning purified silicon tetrachloride in an oxyhydrogen flame, wet silica produced from water glass, sol-gel silica particles obtained by a wet process, gel silica particles, aqueous colloidal silica particles, alcoholic silica particles, molten silica particles obtained by a gas-phase process, and deflagration silica particles. Fumed silica is preferred.

[0076] The silica nanoparticles are preferably spherical silica nanoparticles. "Spherical" includes shapes that are slightly ellipsoidal or slightly missing, even if they are roughly spherical. The average circularity of the silica nanoparticles is preferably 0.900 to 1.000, and more preferably 0.930 to 0.990.

[0077] <Method for measuring water adsorption amount> The amount of moisture adsorbed by silica microparticles is measured using an adsorption equilibrium measuring device (BELSORP-aqua3: manufactured by Nippon Bell Co., Ltd.). This device measures the amount of adsorbed gas (water vapor) of the target gas.

[0078] (Degassing) Before measurement, degas any moisture adsorbed on the sample. Attach the cell, filler rod, and cap, and weigh the empty cell. Weigh 0.3g of sample and place it into the cell. Insert the filler rod into the cell, attach the cap, and connect it to the degassing port. Once all cells to be measured are connected to the degassing ports, open the helium valve. Turn on the button for the degassing port and press the "VAC" button. Degas the cells for at least one day.

[0079] (measurement) Turn on the power to the main unit (there is a switch on the back of the unit). Start the vacuum pump at the same time. Turn on the power to the main unit and control panel for circulating water. Launch "BELaqua3.exe" (measurement software) located in the center of the PC screen. Temperature control of the high-temperature air chamber: Double-click "SV" in the "TIC1" frame on the "Flow Diagram" window to open the "Temperature Setting" window. Enter the temperature (80℃) and click Set.

[0080] Controlling the adsorption temperature: Double-click "SV" under "Adsorption Temperature" in the "Flow Diagram" window and enter the "SV value" (adsorption temperature). Click "Start Circulation" and "Outside Temperature Control," then click "Settings."

[0081] Press the "PURGE" button to stop degassing, turn off the port button, remove the sample, attach cap 2, weigh the sample, and then attach the sample to the main unit's measuring section. On the PC, click "Measurement Conditions" to open the "Measurement Conditions Settings" window. The measurement conditions are as follows:

[0082] Air bath temperature: 80.0°C, Adsorption temperature: 30.0°C, Adsorbate name: H2O, Equilibrium time: 500 sec, Temperature waiting time: 60 min, Saturated vapor pressure: 4.245 kPa, Sample tube pumping speed: Normal, Chemistry: Not measured, Initial introduction volume: 0.20 cm 3 (STP)·g -1 Number of relative pressure measurement ranges: 4

[0083] Select the number of samples to measure, enter the "Measurement Data File Name" and "Sample Weight," and then start the measurement.

[0084] (analysis) The analysis software was launched and the amount of water adsorbed per unit mass at a relative water vapor pressure of 80% (cm³) was calculated. 3 The amount of water adsorbed per unit mass is calculated by dividing the calculated amount of water adsorbed per unit mass by the BET specific surface area of ​​the silica nanoparticles obtained by the method described below. 3 / m 2is obtained.

[0085] <Measurement of BET Specific Surface Area> The BET specific surface area of silica fine particles can be determined according to the BET method (multi-point BET method) by low-temperature gas adsorption using a dynamic constant pressure method. Using a specific surface area analyzer (trade name: Gemini 2375 Ver.5.0, manufactured by Shimadzu Corporation), nitrogen gas is adsorbed onto the surface of a sample, and measurement is performed using the multi-point BET method, whereby the BET specific surface area (m 2 / g) can be calculated.

[0086] The number-average particle diameter of primary particles of the silica fine particles is preferably 5 nm or more and 500 nm or less, more preferably 8 nm or more and 310 nm or less, still more preferably 50 nm or more and 300 nm or less, and particularly preferably 50 nm or more and 200 nm or less. This allows the silica fine particles to appropriately cover the toner particles, and also makes it easier for the silica fine particles adhering to the photoconductor to form a closest-packed structure at the cleaning nip portion. As a result, slipping-through of the external additive can be suppressed, and the effect of suppressing ghost caused by external additive carryover is improved.

[0087] The number-average particle diameter of primary particles of the silica fine particles can be adjusted by controlling conditions such as the reaction step, pulverization step, and classification step in the production process of the silica fine particles.

[0088] [Titanate Compound Fine Particles] For the titanate compound fine particles in the present invention, it is necessary that the number-average particle diameter of primary particles of the titanate compound fine particles is 10 nm or more and 100 nm or less, and the average circularity of primary particles of the titanate compound fine particles is 0.700 or more and 1.00 or less, in order to exhibit a good polishing effect on the surface of the photoconductor while suppressing scratches on the photoconductor.

[0089] The number-average particle diameter of primary particles of the titanate compound fine particles is preferably 10 nm or more and 70 nm or less, and more preferably 10 nm or more and 50 nm or less. The number-average particle diameter of primary particles of the titanate compound fine particles can be controlled by adjusting the raw material concentration, reaction temperature and reaction time.

[0090] On the other hand, the average circularity of the titanate compound fine particles is preferably 0.800 to 0.930, and more preferably 0.800 to 0.900. By controlling the average circularity within the above range, scratches on the photoreceptor, polishing effects, and ghosting due to external additive penetration are well suppressed.

[0091] In the present invention, it is preferable that the number-average particle size A of the silica fine particles is greater than the number-average particle size B of the primary particles of the titanate compound fine particles. When the number-average particle size A of the silica fine particles is greater than the number-average particle size B of the titanate compound fine particles, the titanate compound fine particles are effectively collected in the silica layer of the cleaning nip, suppressing slippage and enhancing the polishing effect of the photoreceptor.

[0092] The content of titanate compound fine particles is preferably 0.05 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of toner particles, and more preferably 0.1 parts by mass or more and 1.5 parts by mass or less.

[0093] The titanate compound fine particles used include potassium titanate, barium titanate, strontium titanate, calcium titanate, magnesium titanate, lead titanate, aluminum titanate, and lithium titanate. In particular, strontium titanate and calcium titanate are preferred for obtaining a polishing effect on the photoreceptor.

[0094] The titanate compound fine particles are preferably surface-treated as needed for the purpose of hydrophobicity and triboelectric control. Examples of treatment agents include unmodified silicone varnish, various modified silicone varnishes, unmodified silicone oil, various modified silicone oils, silane coupling agents, silane compounds having functional groups, or other organosilicon compounds. Various treatment agents may be used in combination. Among these, treatment with a silane coupling agent is particularly preferred. In other words, it is preferable that the titanate compound fine particles are surface-treated fine particles with a silane coupling agent.

[0095] Examples of silane coupling agents include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(β-methoxyethoxy)silane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, phenyltrimethoxysilane, and diphthoxysilane. Examples include phenyldimethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, n-butyltrimethoxysilane, isobutyltrimethoxysilane, trimethylmethoxysilane, n-hexyltrimethoxysilane, n-octyltrimethoxysilane, n-octyltriethoxysilane, n-decyltrimethoxysilane, hydroxypropyltrimethoxysilane, n-hexadecyltrimethoxysilane, n-octadecyltrimethoxysilane, trifluoropropyltrimethoxysilane, and hydrolysates thereof.

[0096] Among these, n-octyltriethoxysilane, isobutyltrimethoxysilane, and trifluoropropyltrimethoxysilane are preferred, with isobutyltrimethoxysilane being more preferred. Furthermore, these treatment agents may be used individually or in combination of two or more.

[0097] Titanate compound nanoparticles may be doped with metallic elements other than those constituting the titanate salt. There are no particular restrictions on the metallic elements used for doping, but examples include lanthanum, silicon, aluminum, magnesium, calcium, manganese, rhodium, ruthenium, iridium, tantalum, chromium, antimony, nickel, rhodium, and niobium. Among these, lanthanum is preferred for controlling circularity.

[0098] While there are no particular restrictions on the preparation method of titanate compound fine particles, for example, strontium titanate can be produced by the following method: A dispersion of titania sol obtained by adjusting the pH of a hydrated titanium oxide slurry obtained by hydrolyzing an aqueous solution of titanyl sulfate is mixed with strontium nitrate, strontium chloride, etc., and after heating to the reaction temperature, an alkaline aqueous solution is added to the dispersion. The reaction temperature is preferably 60 to 100°C.

[0099] In the step of adding an alkaline aqueous solution to control the number-average particle size and circularity of the primary particles, it is preferable to limit the time spent adding the alkaline aqueous solution to 60 minutes or less. Furthermore, in the step of adding the alkaline aqueous solution, it is preferable to add it while applying ultrasonic vibrations to control the circularity.

[0100] Furthermore, rapidly cooling the aqueous solution after the reaction is complete by adding an alkaline aqueous solution is preferable for controlling the primary particle size and circularity. Methods of rapid cooling include, for example, adding pure water cooled to 10°C or below until the desired temperature is reached. Rapid cooling allows for high control of circularity during the cooling process.

[0101] <Average particle size of external additives> The number and particle size (maximum diameter) of silica microparticles and titanate compound microparticles present on the surface of toner particles can be determined by observing them with a scanning electron microscope (SEM). Energy-dispersive X-ray spectroscopy (EDS), which is associated with the SEM, can be used to confirm that the measured material is either silica microparticles or titanate compound microparticles. The average particle size is calculated by measuring 100 toner particles and averaging the results.

[0102] <Measurement of the average circularity of external additives> Silica nanoparticles and titanate compound nanoparticles were imaged using a scanning electron microscope (SEM) at a magnification of 25,000x and a resolution of 1280 x 960 pixels (each pixel being approximately 4 nm x 4 nm). The acquired images were then analyzed using ImageJ image analysis software (available from https: / / imagej.nih.gov / ij / ) to determine their circularity.

[0103] First, contour extraction is performed on silica microparticles or titanate compound microparticles, and their projected area S and perimeter L are measured.

[0104] Next, the equivalent diameter and circularity are determined using the area S and perimeter L mentioned above. The equivalent diameter is the diameter of a circle with the same area as the projected area of ​​the particle image, and the circularity is defined as the value obtained by dividing the perimeter of the circle obtained from the equivalent diameter by the perimeter of the particle projection image, and is calculated by the following formula. Circularity = 2 × (π × S) 1 / 2 / L

[0105] The above circularity is calculated for at least 100 silica microparticles, and the arithmetic mean is taken as the average circularity of the silica microparticles or titanate compound microparticles.

[0106] [Toner particle composition] (Binding resin) The toner particles contain a binder resin, and known binder resins can be used for the toner particles. For example, the following are examples of binder resins.

[0107] Styrene resins, styrene copolymer resins, polyester resins, polyol resins, polyvinyl chloride resins, phenol resins, naturally modified phenol resins, naturally modified maleic acid resins, acrylic resins, methacrylic resins, polyvinyl acetate, silicone resins, polyurethane resins, polyamide resins, furan resins, epoxy resins, xylene resins, polyvinyl butyral, terpene resins, coumarone indene resins, and petroleum resins. Preferably used resins include styrene copolymer resins, polyester resins, and hybrid resins obtained by mixing polyester resin and styrene copolymer resin or by partial reaction of both. Preferably, polyester resin is used.

[0108] The components that make up polyester resin are described in detail. Note that depending on the type and application, one or more of the following components may be used.

[0109] Examples of divalent carboxylic acid components constituting polyester resins include the following dicarboxylic acids or their derivatives: benzenedicarboxylic acids such as phthalic acid, terephthalic acid, isophthalic acid, and phthalic anhydride, or their anhydrides or lower alkyl esters; alkyldicarboxylic acids such as succinic acid, adipic acid, sebacic acid, and azelaic acid, or their anhydrides or lower alkyl esters; alkenyl succinic acids or alkyl succinic acids with an average number of carbon atoms of 1 to 50, or their anhydrides or lower alkyl esters; and unsaturated dicarboxylic acids such as fumaric acid, maleic acid, citraconic acid, and itaconic acid, or their anhydrides or lower alkyl esters.

[0110] Examples of alkyl groups in the lower alkyl ester include methyl, ethyl, propyl, and isopropyl groups.

[0111] On the other hand, the following are examples of divalent alcohol components that make up polyester resin.

[0112] Ethylene glycol, polyethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, 2-methyl-1,3-propanediol, 2-ethyl-1,3-hexanediol, 1,4-cyclohexanedimethanol (CHDM), hydrogenated bisphenol A, bisphenols represented by formula (I-1) and their derivatives: and diols represented by formula (I-2).

[0113] [ka] (In formula (I-1), R is an ethylene group or a propylene group, x and y are integers greater than or equal to 0, and the average value of x + y is between 0 and 10.)

[0114] [ka] (In formula (I-2), R' is an ethylene group or a propylene group, x' and y' are integers greater than or equal to 0, and the average value of x'+y' is between 0 and 10.)

[0115] In addition to the divalent carboxylic acid component and divalent alcohol component described above, the components of the polyester resin may also contain trivalent or higher carboxylic acid components and trivalent or higher alcohol components.

[0116] There are no particular limitations on the carboxylic acid component with a valency of three or higher, but examples include trimellitic acid, trimellitic anhydride, and pyromellitic acid. Examples of alcohol components with a valency of three or higher include trimethylolpropane, pentaerythritol, and glycerin.

[0117] In addition to the compounds mentioned above, the polyester resin may also contain monovalent carboxylic acid components and monovalent alcohol components. Specifically, examples of monovalent carboxylic acid components include palmitic acid, stearic acid, arachidic acid, behenic acid, cerotic acid, heptacosanoic acid, montanic acid, melissic acid, laxeric acid, tetracontanoic acid, and pentacontanoic acid.

[0118] Other examples of monohydric alcohol components include behenyl alcohol, ceryl alcohol, melicyl alcohol, and tetracontanol.

[0119] (Coloring agent) The toner can be used as a magnetic one-component toner, a non-magnetic one-component toner, or a non-magnetic two-component toner.

[0120] When used as a magnetic single-component toner, magnetic iron oxide particles are preferably used as the colorant. Examples of magnetic iron oxide particles contained in the magnetic single-component toner include magnetic iron oxides such as magnetite, maghemite, and ferrite, and magnetic iron oxides containing other metal oxides; metals such as Fe, Co, and Ni; or alloys of these metals with metals such as Al, Co, Cu, Pb, Mg, Ni, Sn, Zn, Sb, Be, Bi, Cd, Ca, Mn, Se, Ti, W, and V; and mixtures thereof. The content of magnetic iron oxide particles is preferably 30 parts by mass or more and 150 parts by mass or less per 100 parts by mass of the binder resin.

[0121] Examples of colorants used when used as non-magnetic one-component toners and non-magnetic two-component toners include the following:

[0122] As black pigments, carbon blacks such as furnace black, channel black, acetylene black, thermal black, and lamp black are used, as well as magnetic powders such as magnetite and ferrite.

[0123] Suitable colorants for the yellow color include pigments or dyes. Examples of pigments include CI Pigment Yellow 1, 2, 3, 4, 5, 6, 7, 10, 11, 12, 13, 14, 15, 17, 23, 62, 65, 73, 74, 81, 83, 93, 94, 95, 97, 98, 109, 110, 111, 117, 120, 127, 128, 129, 137, 138, 139, 147, 151, 154, 155, 167, 168, 173, 174, 176, 180, 181, 183, 191, and CI Bat Yellow 1, 3, 20. Examples of dyes include CI Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, and 162. These can be used individually or in combination of two or more.

[0124] Suitable colorants for cyan include pigments or dyes. Examples of pigments include CI Pigment Blue 1, 7, 15, 15;1, 15;2, 15;3, 15;4, 16, 17, 60, 62, 66, CI Bat Blue 6, and CI Acid Blue 45. Examples of dyes include CI Solvent Blue 25, 36, 60, 70, 93, 95. These can be used individually or in combination of two or more.

[0125] Suitable colorants for magenta include pigments or dyes. Examples of pigments include CI Pigment Red 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22, 23, 30, 31, 32, 37, 38, 39, 40, 41, 48, 48; 2, 48; 3, 48; 4, 49, 50, 51, 52, 53, 54, 55, 57, 57; 1, 58, 60, 63, 64, 68, Examples include 81, 81; 1, 83, 87, 88, 89, 90, 112, 114, 122, 123, 144, 146, 150, 163, 166, 169, 177, 184, 185, 202, 206, 207, 209, 220, 221, 238, 254, CI Pigment Violet 19; CI Bat Red 1, 2, 10, 13, 15, 23, 29, 35.

[0126] Examples of magenta dyes include oil-soluble dyes such as CI Solvent Red 1, 3, 8, 23, 24, 25, 27, 30, 49, 52, 58, 63, 81, 82, 83, 84, 100, 109, 111, 121, 122, CI Disperse Red 9, CI Solvent Violet 8, 13, 14, 21, 27, and CI Disperse Violet 1, as well as basic dyes such as CI Basic Red 1, 2, 9, 12, 13, 14, 15, 17, 18, 22, 23, 24, 27, 29, 32, 34, 35, 36, 37, 38, 39, 40, and CI Basic Violet 1, 3, 7, 10, 14, 15, 21, 25, 26, 27, and 28. These can be used individually or in combination of two or more.

[0127] The coloring agent content is preferably 1 part by mass or more and 20 parts by mass or less per 100 parts by mass of the binder resin.

[0128] (Release agent) A release agent (wax) may be used to give the toner release properties.

[0129] Examples of waxes include: aliphatic hydrocarbon waxes such as low molecular weight polyethylene, low molecular weight polypropylene, olefin copolymers, microcrystalline wax, paraffin wax, and Fischer-Tropsch wax; oxidized forms of aliphatic hydrocarbon waxes such as oxidized polyethylene wax; waxes mainly composed of fatty acid esters such as carnauba wax, behenyl behenate, and montanate ester wax; and waxes in which fatty acid esters have been partially or completely deoxidized, such as deoxidized carnauba wax.

[0130] Furthermore, saturated linear fatty acids such as palmitic acid, stearic acid, and montanic acid; unsaturated fatty acids such as brassic acid, eleostearic acid, and valinalic acid; saturated alcohols such as stearyl alcohol, aralkyl alcohol, behenyl alcohol, carnaubyl alcohol, ceryl alcohol, and melissyl alcohol; polyhydric alcohols such as sorbitol; fatty acid amides such as linoleic acid amide, oleic acid amide, and lauric acid amide; saturated fatty acid bisamides such as methylenebisstearate, ethylenebiscaprate, ethylenebislaurate, and hexamethylenebisstearate; ethylenebisoleamide, hexamethylenebisoleamide, N,N Examples include unsaturated fatty acid amides such as '-dioleyl adipic acid amide and N,N'-dioleyl sebacin acid amide; aromatic bisamides such as m-xylene bisstearamide and N,N'-distearyl isophthalic acid amide; fatty acid metal salts (generally known as metal soaps) such as calcium stearate, calcium laurate, zinc stearate, and magnesium stearate; waxes grafted onto aliphatic hydrocarbon waxes with vinyl copolymer monomers such as styrene and acrylic acid; partially esterified fatty acids and polyhydric alcohols such as behenic acid monoglyceride; and methyl ester compounds having hydroxyl groups obtained by hydrogenation of vegetable oils and fats.

[0131] Particularly preferred waxes are aliphatic hydrocarbon waxes. For example, preferred waxes include low molecular weight hydrocarbons obtained by radical polymerization of alkylenes under high pressure or polymerization of Ziegler catalysts or metallocene catalysts under low pressure; Fischer-Tropsch waxes synthesized from coal or natural gas; paraffin waxes; olefin polymers obtained by thermal decomposition of high molecular weight olefin polymers; synthetic hydrocarbon waxes obtained from the distillation residue of hydrocarbons obtained by the Aage process from synthesis gas containing carbon monoxide and hydrogen, or synthetic hydrocarbon waxes obtained by hydrogenation of these.

[0132] Furthermore, it is more preferable to use hydrocarbon waxes that have been separated by methods such as press efflorescence, solvent method, vacuum distillation, or fractional crystallization. In particular, among paraffin waxes, n-paraffin wax and Fischer-Tropsch wax, which mainly consist of linear components, are preferred from the viewpoint of molecular weight distribution.

[0133] These waxes may be used individually or in combination of two or more types. Preferably, the wax is added in an amount of 1 to 20 parts by mass per 100 parts by mass of the binder resin.

[0134] (Charge control agent) A charge control agent may be used in the toner. Known charge control agents can be used. Examples include azo iron compounds, azo chromium compounds, azo manganese compounds, azo cobalt compounds, azo zirconium compounds, chromium compounds of carboxylic acid derivatives, zinc compounds of carboxylic acid derivatives, aluminum compounds of carboxylic acid derivatives, and zirconium compounds of carboxylic acid derivatives. Aromatic hydroxycarboxylic acids are preferred as the carboxylic acid derivatives. A charge control resin can also be used. One or more charge control agents may be used in combination as needed. It is preferable to use 0.1 parts by mass or more and 10 parts by mass of the charge control agent per 100 parts by mass of the binder resin.

[0135] [Addition of external additives to toner particles] (Additional amount / addition method) The toner comprises toner particles and silica fine particles and titanate compound fine particles on the surface of the toner particles. The toner can be obtained by externally adding silica fine particles and titanate compound fine particles to the toner particles as external additives. The silica fine particle content in the toner is preferably 0.01 parts by mass or more and 10.00 parts by mass or less, more preferably 1.00 parts by mass or more and 8.00 parts by mass or less, and even more preferably 3.00 parts by mass or more and 6.00 parts by mass or less, per 100 parts by mass of toner particles.

[0136] This allows silica microparticles to more adequately coat toner particles, enables proper control of the amount adhering to the photoreceptor, forms a stronger layer in the cleaning nip area, and improves the suppression of ghosting caused by external additives.

[0137] Furthermore, the content of titanate compound fine particles in the toner is preferably 0.05 parts by mass or more and 2.00 parts by mass or less per 100 parts by mass of toner particles, and more preferably 0.10 parts by mass or more and 1.50 parts by mass or less.

[0138] The addition of external additives such as silica microparticles and titanate compound microparticles to toner particles can be done by mixing the toner particles and the external additives using a mixer as described below.

[0139] Examples of mixing machines include: Henschel mixer (manufactured by Mitsui Mining Co., Ltd.); Super Mixer (manufactured by Kawata Co., Ltd.); Ribocone (manufactured by Okawara Seisakusho Co., Ltd.); Nauter mixer, Turbulizer, Cyclomix (manufactured by Hosokawa Micron Co., Ltd.); Spiral Pin Mixer (manufactured by Taiheiyo Kiko Co., Ltd.); and Redigge mixer (manufactured by Matsubo Co., Ltd.).

[0140] (Embedding rate of silica microparticles) It is preferable that a portion of the silica fine particles are embedded on the surface of the toner particles. In the case of silica fine particles embedded on the surface of the toner particles, the embedding rate of the silica fine particles in the toner particles is preferably 5% to 50%, more preferably 5% to 40%, even more preferably 10% to 30%, particularly preferably 12% to 25%, and especially preferably 14% to 20%.

[0141] By keeping the embedding rate within the above range, the adhesion force of the toner attached to the photoreceptor surface can be effectively reduced, thereby suppressing toner fusion.

[0142] <Calculation of the embedding rate of silica microparticles on the surface of toner particles> First, as a pretreatment, silica microparticles that are not embedded or have a low embedding rate are separated from the toner. 20g of a 10% aqueous solution of "Contaminon N" (a pH 7 neutral detergent for cleaning precision measuring instruments consisting of a nonionic surfactant, anionic surfactant, and organic builder) is weighed into a 50mL vial and mixed with 1g of toner.

[0143] Place the toner in an Iwaki Sangyo Co., Ltd. "KM Shaker" (model: V.SX), set the speed to 50, and shake for 30 seconds. This will cause any unburied silica particles to migrate from the toner particle surface to the aqueous solution.

[0144] Subsequently, in the case of magnetic toner containing magnetic material, the toner particles are restrained using a neodymium magnet, and the silica microparticles that have migrated to the supernatant liquid are separated. The settled toner particles are then dried under vacuum (40°C / 24 hours) to obtain the sample.

[0145] For non-magnetic toners, a centrifuge (H-9R; manufactured by Kokusan Co., Ltd.) (1000 rpm for 5 minutes) is used to separate the toner particles from the unburied silica microparticles that have migrated to the supernatant liquid. The remaining toner particles are collected as powder by suction filtration and then dried.

[0146] Toner particles are fixed to the sample stage of an electron microscope using carbon tape, and the toner particles are observed under the following conditions: Images are taken from areas where the inclination angle of the toner particle surface is large (for example, 70-110°, preferably around 90°). • Equipment used: Hitachi High-Technologies Corporation SU8220 Acceleration voltage: 2kV Emission current: 10μA Image acquisition: Secondary electron detector Image magnification: 50000x Pixel count: 1280 x 960 (each pixel is approximately 2nm x 2nm)

[0147] The acquired images are analyzed using the image analysis software ImageJ (available from https: / / imagej.nih.gov / ij / ). As shown in Figure 1, silica nanoparticles are fitted into a perfect circle (a perfect circle is created by using [Oval selections] (the shape is fixed as a perfect circle when operating while holding down the shift key)), and the embedding rate is calculated from the diameter a of the silica nanoparticle and the length b of the part where the silica nanoparticle is embedded using the following formula. The length b is measured on a straight line passing through the top of the embedded side in the depth direction and the center of the silica nanoparticle in the silica nanoparticle fitted into a perfect circle. Embedding rate (%) = Length of the portion where silica nanoparticles are embedded b / Diameter of silica nanoparticle a

[0148] The above embedding rate is calculated for at least 100 silica microparticles, and the arithmetic mean is taken as the embedding rate of the silica microparticles.

[0149] The embedding rate of silica microparticles can be controlled, for example, by adjusting the temperature when mixing toner particles and silica microparticles in a mixer as described above. Alternatively, it can be controlled by performing a surface treatment (silica microparticle embedding treatment) on the toner particles after mixing the toner particles and silica microparticles, and adjusting the conditions (temperature of the treatment atmosphere and exhaust air volume of the treatment space). Heat treatment is preferred for the surface treatment. For example, treatment with hot air can be used. Titanate compound microparticles may also be mixed when mixing toner particles and silica microparticles.

[0150] (Surface treatment of toner particles) Surface treatment of toner particles can be performed using the following equipment: Hybridization System (manufactured by Nara Machine Works), Novilta (manufactured by Hosokawa Micron Corporation), Mechanofusion System (manufactured by Hosokawa Micron Corporation), Faculty (manufactured by Hosokawa Micron Corporation), Inomizer (manufactured by Hosokawa Micron Corporation), Theta Composer (manufactured by Tokuju Kogyo Co., Ltd.), MechanoMill (manufactured by Okada Seikou Co., Ltd.), and Meteor Rainbow MR Type (manufactured by Nippon Pneumatic Co., Ltd.).

[0151] Furthermore, the silica microparticles and titanate compound microparticles may be added externally after the embedding process is carried out using the method described above.

[0152] The following provides a specific example of a method for surface-treating toner particles (for example, toner particles mixed with externally added silica fine particles) using hot air, employing the heat treatment apparatus shown in Figure 2. In this example, toner particles are referred to as the workpiece.

[0153] The material to be processed, supplied in a fixed quantity by the raw material quantitative supply means 1, is guided by compressed gas adjusted by the compressed gas flow rate adjustment means 2 into an introduction pipe 3 installed vertically to the raw material supply means. The material to be processed, having passed through the introduction pipe 3, is uniformly dispersed by a conical projection member 4 located in the center of the raw material supply means, and is guided into eight radially spreading supply pipes 5 to a processing chamber 6 where heat treatment takes place.

[0154] At this time, the material to be processed supplied to the processing chamber 6 has its flow restricted by a restricting means 9 provided within the processing chamber 6 to regulate the flow of the material to be processed. As a result, the material supplied to the processing chamber 6 is heat-treated while swirling around inside the processing chamber 6, and then cooled.

[0155] The hot air used to heat-treat the supplied material is supplied from the hot air supply means 7, distributed by the distribution member 12, and introduced into the processing chamber 6 in a spiral motion by the swirling member 13 for swirling the hot air. The swirling member 13 for swirling the hot air has multiple blades, and the swirling of the hot air can be controlled by the number and angle of these blades (note that 11 indicates the outlet of the hot air supply means).

[0156] The hot air supplied into the processing chamber 6 preferably has a temperature of 100°C to 300°C at the outlet of the hot air supply means 7, and more preferably 130°C to 190°C. If the temperature at the outlet of the hot air supply means 7 is within the above range, it is possible to prevent fusion or coalescence due to overheating of the workpiece while maintaining a desirable embedding rate for the silica fine particles. The hot air is supplied from the hot air supply means 7.

[0157] Furthermore, the heat-treated resin particles are cooled by cold air supplied from the cold air supply means 8. The temperature of the cold air supplied from the cold air supply means 8 is preferably between -20°C and 30°C. If the temperature of the cold air is within the above range, the heat-treated workpiece can be cooled efficiently, and fusion or coalescence of the workpiece is less likely to occur. Also, the absolute moisture content of the cold air is 0.5 g / m³. 3 More than 15.0g / m 3 The following is preferable:

[0158] Next, the cooled material to be processed is collected by a collection means 10 located at the lower end of the processing chamber 6. A blower (not shown) is provided at the end of the collection means 10, which is used to suction and transport the material.

[0159] Furthermore, the powder particle supply port 14 is positioned so that the direction of rotation of the supplied material to be processed and the direction of rotation of the hot air are the same, and the recovery means 10 is also positioned tangentially on the outer periphery of the processing chamber 6 to maintain the rotation direction of the rotated material to be processed. In addition, the cold air supplied from the cold air supply means 8 is configured to be supplied horizontally and tangentially from the outer periphery of the device to the circumferential surface of the processing chamber.

[0160] The swirling direction of the material to be processed supplied from the powder particle supply port 14, the swirling direction of the cold air supplied from the cold air supply means 8, and the swirling direction of the hot air supplied from the hot air supply means 7 are all in the same direction. As a result, turbulence does not occur in the processing chamber, the swirling flow within the apparatus is strengthened, and a strong centrifugal force is applied to the material to be processed before heat treatment, further improving dispersibility, making it easier to obtain toner particles with fewer aggregated particles.

[0161] [Method for manufacturing toner particles] In the process of obtaining toner particles, the method for producing toner particles is not particularly limited and can be produced by known methods. Examples include grinding, emulsification and agglutination, suspension polymerization, and dissolution and suspension methods.

[0162] (Crushing method) Toner particles produced by the pulverization method are manufactured, for example, as follows:

[0163] The binder resin, colorant, and other additives as needed are thoroughly mixed using a mixer such as a Henschel mixer or ball mill. The mixture is then melt-kneaded using a thermal kneader such as a twin-screw extruder, heated roll, kneader, or extruder. Wax, magnetic iron oxide particles, and metal-containing compounds can also be added at this stage.

[0164] After the molten mixture is cooled and solidified, it is crushed and classified to obtain toner particles. During this process, the embedding rate of silica microparticles on the surface of the toner particles can be controlled by adjusting the exhaust temperature during fine grinding. The toner particles and external additives such as silica microparticles are then mixed using a mixer such as a Henschel mixer to obtain the toner.

[0165] Examples of mixing machines include: Henschel mixer (manufactured by Mitsui Mining Co., Ltd.); Super Mixer (manufactured by Kawata Co., Ltd.); Ribocone (manufactured by Okawara Seisakusho Co., Ltd.); Nauter mixer, Turbulizer, Cyclomix (manufactured by Hosokawa Micron Co., Ltd.); Spiral Pin Mixer (manufactured by Taiheiyo Kiko Co., Ltd.); and Redigge mixer (manufactured by Matsubo Co., Ltd.).

[0166] Examples of mixing machines include: KRC kneader (manufactured by Kurimoto Iron Works); Buss-Co kneader (manufactured by Buss); TEM type extruder (manufactured by Toshiba Machine Co.); TEX twin-screw mixer (manufactured by Japan Steel Works); PCM mixer (manufactured by Ikegai Iron Works); three-roll mill, mixing roll mill, kneader (manufactured by Inoue Seisakusho); NideX (manufactured by Mitsui Mining Co.); MS type pressurized kneader, kneader-ruder (manufactured by Moriyama Seisakusho); Banbury mixer (manufactured by Kobe Steel).

[0167] Examples of crushing machines include: counter jet mill, micron jet, inomizer (manufactured by Hosokawa Micron Co., Ltd.); IDS type mill, PJM jet crusher (manufactured by Nippon Pneumatic Mfg. Co., Ltd.); cross jet mill (manufactured by Kurimoto Iron Works Co., Ltd.); Ulmax (manufactured by Nisso Engineering Co., Ltd.); SK Jet-O-Mill (manufactured by Seishin Enterprise Co., Ltd.); Cryptron (manufactured by Kawasaki Heavy Industries, Ltd.); Turbo Mill (manufactured by Turbo Industries Co., Ltd.); and Super Rotor (manufactured by Nisshin Engineering Co., Ltd.).

[0168] Furthermore, if necessary, after grinding, the surface treatment of the toner particles can be performed using a hybridization system (manufactured by Nara Machine Works), Nobilta (manufactured by Hosokawa Micron Corporation), Mechanofusion system (manufactured by Hosokawa Micron Corporation), Faculty (manufactured by Hosokawa Micron Corporation), Inomizer (manufactured by Hosokawa Micron Corporation), Theta Composer (manufactured by Tokuju Kogyo Co., Ltd.), Mechanomill (manufactured by Okada Seikou Co., Ltd.), or Meteor Rainbow MR Type (manufactured by Nippon Pneumatic Co., Ltd.) to control the embedding rate of silica microparticles on the surface of the toner particles.

[0169] Examples of classifiers include: Classil, Micron Classifier, Spedick Classifier (manufactured by Seishin Corporation); Turbo Classifier (manufactured by Nisshin Engineering Co., Ltd.); Micron Separator, Turboplex (ATP), TSP Separator (manufactured by Hosokawa Micron Corporation); Elbow Jet (manufactured by Nippon Steel Mining Co., Ltd.), Dispersion Separator (manufactured by Nippon Pneumatic Mfg. Co., Ltd.); and YM Microcut (manufactured by Yaskawa Trading Co., Ltd.).

[0170] Examples of sieving devices used to separate coarse particles include: Ultrasonic (manufactured by Koei Sangyo Co., Ltd.); Resona Sieve, Gyro Shifter (manufactured by Tokuju Kogyo Co., Ltd.); Vibrasonic System (manufactured by Dalton Co., Ltd.); Soniclean (manufactured by Shinto Kogyo Co., Ltd.); Turbo Screener (manufactured by Turbo Engineering Co., Ltd.); Micro Shifter (manufactured by Makino Sangyo Co., Ltd.); and circular vibrating screen.

[0171] (Emulsification aggregation method) Toner particles are manufactured by emulsification and agglutination, for example, as shown below.

[0172] • Steps to prepare a resin fine particle dispersion (preparation step): For example, polyester resin or styrene-acrylic resin is dissolved in an organic solvent to form a homogeneous solution. Then, basic compounds or surfactants are added as needed. An aqueous medium is slowly added to this solution while applying shear force using a homogenizer or the like to form resin microparticles of the binder resin. Finally, the organic solvent is removed to prepare a resin microparticle dispersion.

[0173] When preparing a resin fine particle dispersion, the amount of resin component to be dissolved in the organic solvent is preferably 10 parts by mass or more and 50 parts by mass or less, and more preferably 30 parts by mass or more and 50 parts by mass or less, per 100 parts by mass of the organic solvent.

[0174] Any organic solvent capable of dissolving the resin components can be used, but solvents with high solubility for olefin resins, such as toluene, xylene, and ethyl acetate, are preferred.

[0175] The surfactant is not particularly limited. Examples include anionic surfactants such as sulfate esters, sulfonates, carboxylates, 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.

[0176] Examples of basic compounds include inorganic bases such as sodium hydroxide and potassium hydroxide, and organic bases such as triethylamine, trimethylamine, dimethylaminoethanol, and diethylaminoethanol. These basic compounds may be used individually or in combination of two or more.

[0177] ·Agglomeration process: The aggregation process involves, for example, mixing the resin microparticle dispersion with a coloring agent microparticle dispersion, a wax microparticle dispersion, and a silicone oil emulsion as needed to prepare a mixture, and then agglomerating the microparticles contained in the prepared mixture to form aggregate particles.

[0178] Suitable methods for forming aggregate particles include adding and mixing a flocculant into the above-mentioned mixed liquid, and then increasing the temperature or applying mechanical power as appropriate.

[0179] A dispersion of colorant microparticles is prepared by dispersing the colorant described above. The colorant microparticles are dispersed by known methods, but media-type dispersers such as rotary shear homogenizers, ball mills, sand mills, and attritors, and high-pressure opposing impact dispersers are preferably used. In addition, surfactants or polymer dispersants that impart dispersion stability can be added as needed.

[0180] Wax particulate dispersions and silicone oil emulsions are prepared by dispersing each material in an aqueous medium. Each material is dispersed by known methods, but media-type dispersers such as rotary shear homogenizers, ball mills, sand mills, and attritors, and high-pressure opposing impact dispersers are preferably used. In addition, surfactants or polymer dispersants that impart dispersion stability can be added as needed.

[0181] Examples of flocculants include monovalent metal salts such as sodium and potassium; divalent metal salts such as calcium and magnesium; trivalent metal salts such as iron and aluminum; and polyvalent metal salts such as polyaluminum chloride. From the viewpoint of particle size controllability in the flocculation process, divalent metal salts such as calcium chloride and magnesium sulfate are preferred.

[0182] The addition and mixing of the flocculant is preferably carried out within a temperature range of room temperature to 75°C. Under these temperature conditions, the flocculation proceeds in a stable manner. The mixing can be carried out using known mixing devices, homogenizers, mixers, etc.

[0183] ·Fusion process: The fusion process involves heating the aggregate particles to a temperature preferably above the melting point of the olefin resin and fusing them together to produce particles with a smooth surface.

[0184] Before proceeding to the fusion process, chelating agents, pH adjusters, surfactants, etc., can be added as appropriate to prevent fusion between the resulting resin particles.

[0185] Examples of chelating agents include alkali metal salts such as ethylenediaminetetraacetic acid (EDTA) and its sodium salt, sodium gluconate, sodium tartrate, potassium citrate and sodium citrate, nitrilotriacetate (NTA) salts, and many water-soluble polymers (polyelectrolytes) that contain both COOH and OH functionalities.

[0186] The time required for the fusion process varies depending on the heating temperature; a shorter time is sufficient at higher temperatures, while a longer time is needed at lower temperatures. In other words, the heating and fusion time cannot be precisely defined as it depends on the heating temperature, but it is generally between 10 minutes and 10 hours.

[0187] ·Cooling process: This step involves cooling the temperature of the aqueous medium containing the resin particles obtained in the fusion process. While not particularly limited, the specific cooling rate is approximately 0.1 to 50°C / minute.

[0188] • Cleaning process: The resin particles produced through the above process can be cleaned and filtered repeatedly to remove impurities from them.

[0189] Specifically, it is preferable to wash the resin particles with an aqueous solution containing a chelating agent such as ethylenediaminetetraacetic acid (EDTA) and its sodium salt, and then wash them further with pure water.

[0190] By repeatedly washing and filtering with pure water, metal salts and surfactants in the resin particles can be removed. From the viewpoint of manufacturing efficiency, 3 to 20 filtrations are preferable, and 3 to 10 filtrations are more preferable.

[0191] ·Drying and classification process: Toner particles can be obtained by drying the washed resin particles and classifying them as appropriate.

[0192] (Dissolution and suspension method) Toner particles produced by the dissolution-suspension method are manufactured, for example, as follows:

[0193] In the dissolution-suspension method, a resin composition obtained by dissolving a binder resin component, such as polyester resin or styrene-acrylic resin, in an organic solvent is dispersed in an aqueous medium to granulate particles of the resin composition. Toner particles are then produced by removing the organic solvent contained in the particles of the resin composition.

[0194] This dissolution and suspension method is applicable to any resin component that dissolves in an organic solvent, and it also allows for easy shape control depending on the conditions during solvent removal.

[0195] The following describes, but is not limited to, a toner manufacturing method using the dissolution suspension method.

[0196] ·Resin component dissolution process: In the resin component dissolution step, the binder resin, and optionally other components such as colorants, waxes, and silicone oils, are dissolved or dispersed in an organic solvent to prepare the resin composition.

[0197] Any organic solvent capable of dissolving the resin components can be used. Specifically, examples include toluene, xylene, chloroform, methylene chloride, and ethyl acetate. However, toluene and ethyl acetate are preferred due to their ability to promote crystallization of crystalline resins and their ease of solvent removal.

[0198] There are no restrictions on the amount of organic solvent used, but it should be an amount that allows the resin composition to disperse in a poor medium such as water and achieve a viscosity that enables granulation. Specifically, a mass ratio of the resin component, and optionally other components such as colorants, waxes, and silicone oils, to the organic solvent of 10 / 90 to 50 / 50 is preferred from the viewpoint of granulation properties and toner particle production efficiency, as described later.

[0199] On the other hand, the colorants, waxes, and silicone oils do not need to be dissolved in organic solvents; they may be dispersed. When using the colorants, waxes, and silicone oils in a dispersed state, it is preferable to disperse them using a disperser such as a bead mill.

[0200] ·Granulation process: The granulation process is a step in which the obtained resin composition is dispersed in an aqueous medium using a dispersant to obtain a predetermined toner particle size, thereby preparing particles of the resin composition.

[0201] Water is the primary water-based medium used.

[0202] Furthermore, it is preferable that the aqueous medium contains 1% to 30% by mass of a monovalent metal salt. The presence of a monovalent metal salt suppresses the diffusion of organic solvents in the resin composition into the aqueous medium, thereby increasing the crystallinity of the resin components contained in the resulting toner particles.

[0203] As a result, the toner tends to have good blocking resistance and a good particle size distribution.

[0204] Examples of monovalent metal salts include sodium chloride, potassium chloride, lithium chloride, and potassium bromide, of which sodium chloride and potassium chloride are preferred.

[0205] Furthermore, the mixing ratio (mass ratio) of the aqueous medium and the resin composition is preferably aqueous medium / resin composition = 90 / 10 to 50 / 50.

[0206] The above-mentioned dispersant is not particularly limited, but as an organic dispersant, cationic, anionic, and nonionic surfactants can be used, with anionic surfactants being preferred.

[0207] Examples include sodium alkylbenzene sulfonate, sodium α-olefin sulfonate, sodium alkyl sulfonate, and sodium alkyl diphenyl ether disulfonate. On the other hand, examples of inorganic dispersants include tricalcium phosphate, hydroxyapatite, calcium carbonate microparticles, titanium dioxide microparticles, and silica microparticles.

[0208] Of these, the inorganic dispersant tricalcium phosphate is preferred. This is because it has very little adverse effect on granulation properties, stability, and the characteristics of the resulting toner.

[0209] The amount of dispersant added is determined according to the particle size of the granules; as the amount of dispersant added increases, the particle size decreases. For this reason, although the amount of dispersant added varies depending on the desired particle size, it is preferable to use an amount in the range of 0.1% by mass or more and 15.0% by mass or less relative to the resin composition.

[0210] Furthermore, when preparing resin composition particles in an aqueous medium, it is preferable to do so under high-speed shearing conditions. Examples of devices that provide high-speed shearing include various high-speed dispersers and ultrasonic dispersers.

[0211] • Solvent removal process: In the solvent removal process, the organic solvent contained in the particles of the obtained resin composition is removed to produce toner particles. The removal of the organic solvent is preferably carried out while stirring.

[0212] • Washing, drying, and classification process: After the solvent removal step, a washing and drying step may be performed in which the toner particles are washed multiple times with water or the like, filtered, and dried. Furthermore, if a dispersant that dissolves under acidic conditions, such as tricalcium phosphate, is used, it is preferable to wash with hydrochloric acid followed by washing with water. Washing removes the dispersant used for granulation. After washing, toner particles can be obtained by filtering and drying, and then appropriately classifying the material.

[0213] (Suspension polymerization method) Toner particles are manufactured by suspension polymerization, for example, as shown below.

[0214] A polymerizable monomer composition is prepared by uniformly dissolving or dispersing polymerizable monomers that generate a binder resin, colorants, wax components, and polymerization initiators using a disperser such as a homogenizer, ball mill, or ultrasonic disperser. After granulating the polymerizable monomer composition particles by dispersing the polymerizable monomer composition in an aqueous medium, toner particles are obtained by polymerizing the polymerizable monomers in the particles made of the polymerizable monomer composition.

[0215] In this case, it is preferable that the polymerizable monomer composition is prepared by mixing a dispersion in which a colorant is dispersed in a first polymerizable monomer (or a portion of the polymerizable monomers) with at least a second polymerizable monomer (or the remaining polymerizable monomers). That is, by thoroughly dispersing the colorant in the first polymerizable monomer and then mixing it with the second polymerizable monomer together with other toner materials, the colorant can be present in the polymerized particles in a better dispersed state.

[0216] The resulting toner particles may be filtered, washed, dried, and classified by known methods as needed.

[0217] (Process of adding external additives to toner particles) The toner particles obtained by the method described above and the external additive can be mixed using a mixer such as a Henschel mixer to obtain toner.

[0218] The weight-average particle size (D4) of the toner is preferably 4.0 μm or more and 15.0 μm or less. More preferably 4.0 μm or more and 9.0 μm or less, and even more preferably 6.0 μm or more and 8.0 μm or less.

[0219] The weight-average particle size (D4) of the toner can be adjusted, for example, by classifying the toner particles.

[0220] <Method for measuring the weight-average particle size (D4) of toner> The weight-average particle size (D4) of the toner is measured using the "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter), a precision particle size distribution analyzer using the pore electrical resistance method with a 100 μm aperture tube, and the accompanying dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter) for setting measurement conditions and analyzing measurement data, with an effective measurement channel count of 25,000. The measurement data is then analyzed and calculated.

[0221] The electrolytic aqueous solution used for measurement is prepared by dissolving special grade sodium chloride in deionized water to a concentration of approximately 1% by mass; for example, "ISOTON II" (manufactured by Beckman Coulter) can be used.

[0222] Before performing measurements and analysis, configure the dedicated software as follows.

[0223] In the dedicated software's "Change Standard Measurement Method (SOM)" screen, set the total count in control mode to 50,000 particles, the number of measurements to 1, and the Kd value to the value obtained using "Standard Particle 10.0 μm" (manufactured by Beckman Coulter). Press the Threshold / Noise Level measurement button to automatically set the threshold and noise level. Also, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and check the box for flushing the aperture tube after measurement.

[0224] In the dedicated software's "Pulse to Particle Size Conversion Settings Screen," set the bin spacing to logarithmic particle size, the particle size bins to 256 particle size bins, and the particle size range to 2 μm or more and 60 μm or less.

[0225] The specific measurement method is as follows: (1) Pour approximately 200 ml of the electrolytic solution into a 250 ml round-bottom glass beaker specifically designed for the Multisizer 3, set it on the sample stand, and stir the mixture with the stirrer rod at 24 revolutions per second in a counterclockwise direction. Then, use the "Aperture Tube Flash" function of the dedicated software to remove any dirt and air bubbles from inside the aperture tube. (2) Place approximately 30 ml of the electrolytic aqueous solution into a 100 ml flat-bottomed glass beaker, and add approximately 0.3 ml of a diluted solution of "Contaminon N" (a 10% by mass aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, anionic surfactant, and organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) diluted three times by mass with deionized water as a dispersant. (3) Two oscillators with an oscillation frequency of 50 kHz are built in with their phases shifted by 180 degrees, and a predetermined amount of deionized water is placed in the water tank of an ultrasonic dispersion device called "Ultrasonic Dispersion System Tetora150" (manufactured by Nikko Bios Co., Ltd.) with an electrical output of 120 W. Approximately 2 ml of the aforementioned Contaminon N is added to this water tank. (4) Place the beaker from (2) into the beaker fixing hole of the ultrasonic disperser and operate the ultrasonic disperser. Then, adjust the height of the beaker so that the resonance state of the liquid surface of the electrolytic aqueous solution inside the beaker is maximized. (5) While irradiating the aqueous electrolyte solution in the beaker of (4) above with ultrasonic waves, add about 10 mg of toner to the aqueous electrolyte solution little by little and disperse the toner. Then, continue the ultrasonic dispersion treatment for an additional 60 seconds. In addition, for ultrasonic dispersion, adjust appropriately such that the water temperature of the water tank is 10°C or higher and 40°C or lower. (6) Using a pipette, drop the aqueous electrolyte solution with toner dispersed therein obtained in (5) above into the round-bottom beaker of (1) placed in a sample stand, and adjust the measurement concentration to be about 5%. Then, perform measurement until the number of measured particles reaches 50000. (7) Analyze the measurement data with the dedicated software attached to the apparatus, and calculate the weight-average particle diameter (D4). When "Graph / Volume %" is set in the dedicated software, the "average diameter" on the analysis / volume statistical value (arithmetic mean) screen is the weight-average particle diameter (D4).

[0226] [Magnetic Carrier] The toner described above may be mixed with a magnetic carrier for use as a two-component developer. As the magnetic carrier, conventional magnetic carriers such as ordinary ferrite and magnetite, and resin-coated carriers can be used. Further, magnetic material-dispersed resin particles having magnetic powder dispersed in a resin component, or porous magnetic core particles having a resin contained in voids can be used.

[0227] As the magnetic component used for the magnetic material-dispersed resin particles, the following can be used: magnetite particle powder, maghemite particle powder, or magnetic iron oxide particle powder containing at least one selected from the group consisting of silicon oxides, silicon hydroxides, aluminum oxides and aluminum hydroxides added thereto; magnetoplumbite-type ferrite particle powder containing barium, strontium, or barium-strontium; and various magnetic iron compound particle powders such as spinel-type ferrite particle powder containing at least one selected from the group consisting of manganese, nickel, zinc, lithium and magnesium.

[0228] Furthermore, in addition to magnetic components, non-magnetic inorganic compound particle powders such as hematite particle powder, non-magnetic hydrated ferric oxide particle powder, goethite particle powder, titanium oxide particle powder, silica particle powder, talc particle powder, alumina particle powder, barium sulfate particle powder, barium carbonate particle powder, cadmium yellow particle powder, calcium carbonate particle powder, and zinc oxide particle powder may be used in combination with magnetic iron compound particle powder.

[0229] Examples of materials for porous magnetic core particles include magnetite or ferrite. A specific example of ferrite is shown by the following general formula. (M12O) x (M2O) y (Fe2O3) Z

[0230] In the above equation, M1 is a monovalent metal and M2 is a divalent metal. When x + y + z = 1.0, x and y are 0 ≤ (x, y) ≤ 0.8, and z is 0.2. <z<1.0である)

[0231] In the formula, it is preferable to use at least one metal atom selected from the group consisting of Li, Fe, Mn, Mg, Sr, Cu, Zn, and Ca as M1 and M2. Other metals that can be used include Ni, Co, Ba, Y, V, Bi, In, Ta, Zr, B, Mo, Na, Sn, Ti, Cr, Al, Si, and rare earth elements.

[0232] The magnetic carrier preferably has magnetic carrier core particles and a resin coating layer on the surface of the magnetic carrier core particles as a resin-coated carrier. The resin coating layer, for example, coats the surface of the magnetic carrier core particles. The magnetic carrier core particles are preferably porous magnetic core particles that contain resin in their voids.

[0233] Either a thermoplastic resin or a thermosetting resin may be used to fill the voids in the porous magnetic core particles.

[0234] Examples of thermoplastic resins used for filling include: novolac resin, saturated alkyl polyester resin, polyarylate, polyamide resin, and acrylic resin.

[0235] Examples of thermosetting resins include phenolic resins, epoxy resins, unsaturated polyester resins, and silicone resins.

[0236] The method for coating the surface of magnetic carrier core particles with resin is not particularly limited, but examples include immersion, spraying, brush application, and application methods such as a fluidized bed. Among these, the immersion method is preferred.

[0237] The amount of resin coating the surface of the magnetic carrier core particles (amount of resin coating layer) is preferably 0.1 parts by mass or more and 5.0 parts by mass or less per 100 parts by mass of magnetic carrier core particles in order to control the ability to impart charge to the toner.

[0238] Examples of resins used in the resin coating layer include acrylic resins such as acrylic acid ester copolymers and methacrylic acid ester copolymers, styrene-acrylic resins such as styrene-acrylic acid ester copolymers and styrene-methacrylic acid ester copolymers, fluorine-containing resins such as polytetrafluoroethylene, tetrafluoroethylene-hexafluoropropylene copolymer, monochlorotrifluoroethylene polymer, and polyvinylidene fluoride, silicone resins, polyester resins, polyamide resins, polyvinyl butyral, aminoacrylate resins, iomonomer resins, and polyphenylene sulfide resins.

[0239] These resins can be used individually or in combination. Acrylic resins are preferred.

[0240] Among these, a copolymer containing a (meth)acrylic acid ester having an alicyclic hydrocarbon group is particularly preferred from the viewpoint of electrostatic stability. It is preferable that the resin in the resin coating layer has monomer units of a (meth)acrylic acid ester having an alicyclic hydrocarbon group. That is, the resin in the resin coating layer contains a polymer of monomers including at least a (meth)acrylic acid ester having an alicyclic hydrocarbon group.

[0241] (Meth)acrylic acid esters having an alicyclic hydrocarbon group are preferably cyclobutyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate, cycloheptyl acrylate, dicyclopentenyl acrylate, dicyclopentanyl acrylate, cyclobutyl methacrylate, cyclopentyl methacrylate, cyclohexyl methacrylate, cycloheptyl methacrylate, dicyclopentenyl methacrylate, and dicyclopentanyl methacrylate.

[0242] The alicyclic hydrocarbon group is preferably a cycloalkyl group, with a carbon number of 3 to 10, and more preferably 4 to 8. One or more of these may be selected and used.

[0243] Furthermore, the content of monomer units made of (meth)acrylic acid ester having alicyclic hydrocarbon groups in the copolymer used in the resin coating layer (copolymerization ratio based on the mass of (meth)acrylic acid ester) is preferably 5.0% by mass or more and 80.0% by mass or less, more preferably 50.0% by mass or more and 80.0% by mass or less, and even more preferably 70.0% by mass or more and 80.0% by mass or less. Within the above range, good electrostatic properties are obtained in high temperature and high humidity environments.

[0244] Furthermore, from the viewpoint of charging stability, and from the viewpoint of enhancing the adhesion between magnetic carrier core particles and the resin coating layer and suppressing local peeling of the resin coating layer, it is more preferable that the resin in the resin coating layer contains a macromonomer as a copolymerization component. An example of a specific macromonomer is represented by formula (B). That is, it is preferable that the resin in the resin coating layer has a monomer unit derived from a macromonomer represented by the following formula (B).

[0245]

Chemical Formula

[0246] In formula (B), A represents a polymer of at least one compound selected from the group consisting of methyl acrylate, methyl methacrylate, butyl acrylate, butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, styrene, acrylonitrile and methacrylonitrile. R 3 is H or CH3.

[0247] A is preferably a polymer of methyl methacrylate.

[0248] In order to improve the adhesion between the magnetic carrier core particles and the resin coating layer, the weight average molecular weight of the macromonomer is preferably 3,000 or more and 10,000 or less, more preferably 4,000 or more and 7,000 or less.

[0249] In order to improve the adhesion between the magnetic carrier core particles and the resin coating layer, the content of the monomer unit derived from the macromonomer in the resin used for the resin coating layer is preferably 0.5 mass% or more and 30.0 mass% or less, more preferably 10.0 mass% or more and 30.0 mass% or less, and still more preferably 20.0 mass% or more and 25.0 mass% or less.

[0250] <Measurement of weight average molecular weight of macromonomer> The weight-average molecular weight is measured using gel permeation chromatography (GPC) following the procedure below.

[0251] First, the sample to be measured is prepared as follows.

[0252] The sample (the coating resin separated from the magnetic carrier and separated using a preparative apparatus) was mixed with tetrahydrofuran (THF) at a concentration of 5 mg / ml and allowed to stand at room temperature for 24 hours to dissolve the sample in THF. The mixture was then passed through a sample processing filter (Myshori Disc H-25-2, manufactured by Tosoh Corporation) to be used as the GPC sample.

[0253] Next, using a GPC measuring device (HLC-8120GPC, manufactured by Tosoh Corporation), measurements are performed under the following conditions, in accordance with the device's operation manual.

[0254] (Measurement conditions) Equipment: High-speed GPC "HLC8120 GPC" (manufactured by Tosoh Corporation) Columns: Shodex KF-801, 802, 803, 804, 805, 806, 807 (7 columns, manufactured by Showa Denko) Eluent:THF Flow rate: 1.0ml / min Oven temperature: 40.0℃ Sample injection volume: 0.10 ml Furthermore, in calculating the weight-average molecular weight of the sample, the calibration curve used is a molecular weight calibration curve created using standard polystyrene resins (TSK Standard Polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000, A-2500, A-1000, A-500, manufactured by Tosoh Corporation).

[0255] [Image forming method] The toner of the present invention can be used in known image forming methods. Specifically, it is preferably used in image forming methods that include a charging step of charging the surface of a photoreceptor, an electrostatic latent image forming step of forming an electrostatic latent image on the charged photoreceptor, a developing step of developing the electrostatic latent image with toner to form a toner image on the surface of the photoreceptor, a transfer step of transferring the toner image to a recording medium, a fixing step of fixing the toner image on the recording medium, and a cleaning step of bringing a cleaning blade into contact with the photoreceptor to remove residual toner on the photoreceptor.

[0256] The contact force per unit length in the longitudinal direction between the photoreceptor and the cleaning blade is preferably 0.196 N / cm or more and 0.490 N / cm or less.

[0257] By setting the contact force to 0.196 N / cm or higher, toner and external additives adhering to the photoreceptor can be effectively removed. On the other hand, by setting it to 0.490 N / cm or lower, frictional heat between the photoreceptor and the cleaning blade can be suppressed, preventing toner fusion and suppressing the leakage of external additives due to cleaning blade chatter. As a result, toner fusion and leakage of external additives are suppressed, and ghosting caused by external additives is effectively suppressed.

[0258] [Configurations included in embodiments of the present invention] This embodiment includes the following configuration. (Configuration 1) A toner having toner particles and an external additive on the surface of the toner particles, The external additive comprises silica microparticles and titanate compound microparticles. The silica nanoparticles are surface-treated silica nanoparticles, Solid silica fine particles 29 In DD / MAS measurements of Si-NMR, the Si in the structure represented by formula (1) above a Peak PD1 corresponds to the silicon atom shown, and Si in the structure represented by formula (2) above. bA peak PD2 corresponding to the silicon atom shown is observed, and when the area of ​​peak PD1 is taken as SD1 and the area of ​​peak PD2 is taken as SD2, then SD1 and SD2 are 1.2 ≤ (SD1 + SD2) / SD1 ≤ 10.0 Satisfying the conditions, The number-average particle size of the primary particles of the titanate compound fine particles is 10 nm or more and 100 nm or less. A toner characterized in that the average circularity of the primary particles of the titanate compound fine particles is 0.700 or more and 1.00 or less. (Configuration 2) The toner described in Configuration 1, wherein (SD1+SD2) / SD1 is between 1.2 and 6.3. (Configuration 3) Solid silica nanoparticles 29 In DD / MAS measurements of Si-NMR, the Si in the structure represented by the above formula (3) c A peak PQ corresponding to the silicon atom shown is observed, and when the area of ​​the peak PQ is denoted as SQ, then SD1, SD2 and SQ are, (SD1+SD2) / SQ×100≧1.0 Toner according to configuration 1 or 2 that satisfies the requirements. (Configuration 4) Solid silica nanoparticles 29 Using SD1, SD2, and SQ obtained from Si-NMR DD / MAS measurements, the following equation is used: Ca = (SD1 + SD2) / SQ × 100 Ca calculated from, Solid silica microparticles after washing with hexane 29 Si in the structure represented by formula (1) obtained from DD / MAS measurement of Si-NMR a The area SD1w of the peak PD1w corresponding to the silicon atom shown, and the Si in the structure represented by formula (2) above. b The area SD2w of the peak PD2w corresponding to the silicon atom shown, and the Si in the structure represented by formula (3) above. c Using the area SQw of the peak PQw corresponding to the silicon atom shown, the following equation is used: Cb = (SD1w + SD2w) / SQw × 100 The Cb calculated from this is (Ca-Cb) / Ca×100≦30 A toner described in any of configurations 1 to 3 that satisfies the requirements. (Configuration 5) The toner according to any one of Configurations 1 to 4, wherein the number-average particle size of the primary particles of the silica fine particles is 5 nm or more and 500 nm or less. (Configuration 6) The toner according to any one of Configurations 1 to 5, wherein the silica fine particles are contained in an amount of 0.01 parts by mass or more and 10.00 parts by mass or less per 100 parts by mass of toner particles. (Configuration 7) The toner according to any one of Configurations 1 to 6, wherein the titanate compound fine particles are strontium titanate particles or calcium titanate particles. (Configuration 8) The toner according to any one of Configurations 1 to 7, wherein the content of the titanate compound fine particles is 0.05 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of toner particles. (Configuration 9) The number-average particle size A of the silica fine particles is, with respect to the number-average particle size B of the titanate compound fine particles, A>B The toner described in any of configurations 1 to 8. (Configuration 10) The silica fine particles have a BET specific surface area of ​​1 m² at a temperature of 30°C and a relative humidity of 80%. 2 The amount of water absorbed per unit is 0.01 cm 3 / m 2 More than 0.1cm 3 / m 2 The toner described in one of the following configurations 1 to 9. (Configuration 11) Solid silica fine particles 29 In DD / MAS measurements of Si-NMR, the Si in the structure represented by the above formula (3) c A peak PQ corresponding to the silicon atom shown is observed, and when the area of ​​the peak PQ is denoted as SQ, then SD1, SD2 and SQ are, (SD1+SD2) / SQ×100≧1.0 Satisfying the conditions, The solid silica fine particles 29 Using SD1, SD2, and SQ obtained from Si-NMR DD / MAS measurements, the following formula is used: Ca = (SD1 + SD2) / SQ × 100 Ca calculated from, Solid silica microparticles after washing with hexane 29 Si in the structure represented by formula (1) obtained from DD / MAS measurement of Si-NMR a The area SD1w of the peak PD1w corresponding to the silicon atom shown, and the Si in the structure represented by formula (2) above. b The area SD2w of the peak PD2w corresponding to the silicon atom shown, and the Si in the structure represented by formula (3) above. c Using the area SQw of the peak PQw corresponding to the silicon atom shown, the following equation is used: Cb = (SD1w + SD2w) / SQw × 100 The Cb calculated from this is (Ca-Cb) / Ca×100≦30 Satisfying the conditions, The aforementioned silica nanoparticles have a BET specific surface area of ​​1 m² at a temperature of 30°C and a relative humidity of 80%. 2 The amount of water absorbed per unit is 0.01 cm 3 / m 2 More than 0.1cm 3 / m 2 The toner described in one of the following configurations 1 to 10. (Configuration 12) An image forming method comprising: a charging step of charging the surface of a photoreceptor; an electrostatic latent image forming step of forming an electrostatic latent image on the charged photoreceptor; a developing step of developing the electrostatic latent image with toner to form a toner image on the surface of the photoreceptor; a transfer step of transferring the toner image to a recording medium; a fixing step of fixing the toner image on the recording medium; and a cleaning step of bringing a cleaning blade into contact with the photoreceptor to remove residual toner on the photoreceptor, The toner is a toner having toner particles and an external additive on the surface of the toner particles, The external additive comprises silica microparticles and titanate compound microparticles. The silica nanoparticles are surface-treated silica nanoparticles, Solid silica fine particles 29 In DD / MAS measurements of Si-NMR, the Si in the structure represented by formula (1) above aPeak PD1 corresponds to the silicon atom shown, and Si in the structure represented by formula (2) above. b A peak PD2 corresponding to the silicon atom shown is observed, and when the area of ​​peak PD1 is taken as SD1 and the area of ​​peak PD2 is taken as SD2, then SD1 and SD2 are 1.2 ≤ (SD1 + SD2) / SD1 ≤ 10.0 Satisfying the conditions, The number-average particle size of the primary particles of the titanate compound fine particles is 10 nm or more and 100 nm or less. An image forming method characterized in that the average circularity of the primary particles of the titanate compound fine particles is 0.700 or more and 1.00 or less. [Examples]

[0259] The basic structure and features of this disclosure have been described above; the disclosure will now be explained in detail based on examples. However, this disclosure is not limited to these examples. Unless otherwise specified, parts and percentages are based on mass.

[0260] <Example of manufacturing of binder resin 1> • Bisphenol A ethylene oxide (2.2 molar adduct): 50.0 molar parts • Bisphenol A propylene oxide (2.2 molar adduct): 50.0 molar parts Terephthalic acid: 90.0 molar parts • Trimellitus anhydride: 10.0 moles 100 parts by mass of the monomer constituting the above polyester unit was mixed with 500 ppm of titanium tetrabutoxide in a 5-liter autoclave.

[0261] A reflux condenser, moisture separator, N2 gas introduction tube, thermometer, and stirring device were attached to the autoclave, and a condensation polymerization reaction was carried out at 230°C while introducing N2 gas into the autoclave. The reaction time was adjusted to achieve the desired softening point, and after the reaction was completed, the material was removed from the container, cooled, and pulverized to obtain binder resin 1. The softening point of binder resin 1 was 130°C, and the Tg was 57°C.

[0262] The softening point was measured as follows:

[0263] (Measurement of softening point) The softening point is measured using a constant-load extrusion type capillary rheometer, the "Flow Characteristics Evaluation Device Flow Tester CFT-500D" (manufactured by Shimadzu Corporation), according to the manual included with the device. With this device, a constant load is applied from the top of the sample by a piston, the sample filled in the cylinder is heated and melted, and the molten sample is extruded from a die at the bottom of the cylinder. A flow curve showing the relationship between the piston descent amount and temperature can be obtained.

[0264] The softening point is defined as the "melting temperature in the 1 / 2 method" as described in the manual included with the "Flow Characteristics Evaluation Device Flow Tester CFT-500D".

[0265] The melting temperature in the 1 / 2 method was calculated as follows:

[0266] First, we calculate half the difference between the piston's descent Smax at the end of the outflow and the piston's descent Smin at the start of the outflow (let's call this X; X = (Smax - Smin) / 2). Then, the temperature on the flow curve when the piston's descent is the sum of X and Smin is the melting temperature using the 1 / 2 method.

[0267] The sample used for measurement is approximately 1.3 g of sample, compressed at 10 MPa for 60 seconds at 25°C using a tablet molding compressor (e.g., NT-100H, manufactured by NPA Systems Co., Ltd.) to form a cylindrical shape with a diameter of approximately 8 mm. The measurement conditions for CFT-500D are as follows: Test mode: Temperature increase method Starting temperature: 50℃ Achieved temperature: 200℃ Measurement interval: 1.0℃ Heating rate: 4.0℃ / min Piston cross-sectional area: 1,000 cm² 2 Test load (piston load): 10.0 kgf / cm2 (0.9807 MPa) Preheating time: 300 seconds Die hole diameter: 1.0mm Die length: 1.0mm

[0268] <Example of manufacturing silica nanoparticle 1> 500 g of fumed silica (silica microparticle substrate) with an average particle size of 120 nm was placed in a reaction vessel, and the mixture was heated and stirred under nitrogen purging, with the temperature inside the reaction vessel controlled to 330°C.

[0269] Next, octamethylcyclotetrasiloxane vapor was supplied into the reaction vessel at a rate of 8 g / min for 60 minutes as a surface treatment agent. The silica nanoparticle substrate was then surface-treated by heating and stirring for 120 minutes. Afterward, the reaction vessel was purged with nitrogen to remove unreacted surface treatment agents, yielding silica nanoparticles 1. The physical properties of the obtained silica nanoparticles 1 are shown in Table 2.

[0270] <Examples of manufacturing silica microparticles 2-4> Fumed silica with the number-average particle size shown in Table 1 was manufactured in the same manner as silica nanoparticle 1, except that the surface treatment agent and treatment conditions were changed as shown in Table 1. The physical properties of the obtained silica nanoparticles 2 to 4 are shown in Table 2.

[0271] <Example of manufacturing silica microparticle 5> 500 g of fumed silica (silica microparticle substrate) with an average particle size of 200 nm was placed in a reaction vessel, and the mixture was heated and stirred under nitrogen purging, with the temperature inside the reaction vessel controlled to reach 300°C.

[0272] Next, octamethylcyclotetrasiloxane vapor was supplied into the reaction vessel at a rate of 8 g / min for 60 minutes as a surface treatment agent. The silica nanoparticle substrate was then surface-treated by heating and stirring for 120 minutes. Finally, the reaction vessel was purged with nitrogen to remove any unreacted surface treatment agent.

[0273] Next, as a surface treatment agent, polydimethylsiloxane (kinematic viscosity at 25°C: 50 mm) 2 A solution prepared by diluting 15 g of silica (average repeating units n=60) with 150 g of hexane was supplied by spray atomization. Subsequently, the silica microparticles were surface-treated by heating and stirring for 120 minutes to obtain silica microparticles 5. The physical properties of the obtained silica microparticles 5 are shown in Table 2.

[0274] <Example of manufacturing silica microparticle 6> 500 g of fumed silica (silica microparticle substrate) with an average particle size of 300 nm was placed in a reaction vessel, and the mixture was heated and stirred under nitrogen purging, with the temperature inside the reaction vessel controlled to 330°C.

[0275] Next, as a surface treatment agent, polydimethylsiloxane (kinematic viscosity at 25°C: 50 mm) 2 A solution prepared by diluting 25 g of silica (average repeating units n=60) with 250 g of hexane was supplied by spray atomization. Subsequently, the silica nanoparticle substrate was surface-treated by heating and stirring for 30 minutes to obtain silica nanoparticles 6. The physical properties of the obtained silica nanoparticles 6 are shown in Table 2.

[0276] <Manufacturing examples of silica microparticles 7-10> Fumed silica with the number-average particle size shown in Table 1 was manufactured in the same manner as silica nanoparticles 6, except that the surface treatment agent and treatment conditions were changed as shown in Table 1, to obtain silica nanoparticles 7 to 10. The physical properties of the obtained silica nanoparticles 7 to 10 are shown in Table 2.

[0277] <Example of manufacturing silica nanoparticles 11> Fumed silica with a number-average particle size as shown in Table 1 was manufactured in the same manner as silica nanoparticles 1, except that the surface treatment conditions were changed as shown in Table 1. The physical properties of the obtained silica nanoparticles 11 are shown in Table 2.

[0278] [Table 1]

[0279] In Table 1, the amount of treatment agent (parts) indicates the number of parts by mass of the surface treatment agent per 100 parts by mass of silica fine particle substrate.

[0280] [Table 2]

[0281] In Table 2, SD1 represents the area of ​​the peak corresponding to the silicon atom having a D1 unit structure, SD2 represents the area of ​​the peak corresponding to the silicon atom having a D2 unit structure, Ca is (SD1 + SD2) / SQ × 100, and the reduction rate ΔC (%) represents the reduction rate of the amount of siloxane chain after hexane washing compared to before hexane washing.

[0282] <Example of manufacturing titanate compound fine particles 1> A hydrated titanium oxide slurry obtained by hydrolyzing an aqueous solution of titanyl sulfate was washed with an alkaline aqueous solution until the electrical conductivity of the supernatant reached 50 μS / cm, thereby reducing impurities and purifying the solution. Next, hydrochloric acid was added to the hydrated titanium oxide slurry to adjust the pH to 0.7 to obtain a titania sol dispersion.

[0283] To 2.2 moles (in terms of titanium dioxide) of the titania sol dispersion, 1.3 times the molar amount of strontium chloride aqueous solution was added and placed in a reaction vessel, which was then purged with nitrogen gas. Furthermore, pure water was added to a concentration of 1.1 moles / L in terms of titanium dioxide.

[0284] Next, the mixture was stirred and heated to 90°C. Then, while applying ultrasonic vibration, 440 mL of 10N sodium hydroxide aqueous solution was added over 15 minutes, and the reaction was carried out for 20 minutes. After the reaction, 5°C pure water was added to the slurry and it was rapidly cooled to below 30°C, after which the supernatant was removed. Furthermore, a pH 5.0 hydrochloric acid aqueous solution was added to the slurry and stirred for 1 hour to dissolve and remove strontium carbonate, and then the mixture was washed repeatedly with pure water.

[0285] Next, an aqueous hydrochloric acid solution with a pH of 3.0 was added to the slurry, and then 7.0% by mass of isobutyltrimethoxysilane relative to the solid content of the slurry was added and the mixture was stirred for 10 hours. After that, it was neutralized with an aqueous sodium hydroxide solution, filtered through a Nucche filter, and washed with pure water. The resulting cake was dried to obtain titanate compound fine particles 1. The physical properties are shown in Table 3.

[0286] <Example of manufacturing titanate compound fine particles 2> A hydrated titanium oxide slurry obtained by hydrolyzing an aqueous solution of titanyl sulfate was washed with an alkaline aqueous solution until the electrical conductivity of the supernatant reached 50 μS / cm, thereby reducing impurities and purifying the solution. Next, hydrochloric acid was added to the hydrated titanium oxide slurry to adjust the pH to 0.7 to obtain a titania sol dispersion.

[0287] To 2.0 moles (in terms of titanium dioxide) of the titania sol dispersion, 1.2 times the molar amount of strontium chloride aqueous solution was added and placed in a reaction vessel, which was then purged with nitrogen gas. Furthermore, pure water was added to achieve a titanium dioxide concentration of 1.0 mol / L.

[0288] Next, the mixture was stirred and heated to 85°C. Then, while applying ultrasonic vibration, 800 mL of 5N sodium hydroxide aqueous solution was added over 20 minutes, and the reaction was carried out for another 20 minutes. After the reaction, 5°C pure water was added to the slurry and it was rapidly cooled to below 30°C, after which the supernatant was removed. Furthermore, a pH 5.0 hydrochloric acid aqueous solution was added to the slurry and stirred for 1 hour to dissolve and remove strontium carbonate, and then the mixture was washed repeatedly with pure water.

[0289] Next, an aqueous hydrochloric acid solution with a pH of 3.0 was added to the slurry, and then 30.0% by mass of isobutyltrimethoxysilane relative to the solid content of the slurry was added and the mixture was stirred for 10 hours. After that, it was neutralized with an aqueous sodium hydroxide solution, filtered through a Nucche filter, and washed with pure water. The resulting cake was dried to obtain titanate compound fine particles 2. The physical properties are shown in Table 3.

[0290] <Example of manufacturing titanate compound fine particles 3> A hydrated titanium oxide slurry obtained by hydrolyzing an aqueous solution of titanyl sulfate was washed with an alkaline aqueous solution until the electrical conductivity of the supernatant was 100 μS / cm to reduce impurities and purify the solution. Next, hydrochloric acid was added to the hydrated titanium oxide slurry to adjust the pH to 0.7 to obtain a titania sol dispersion.

[0291] To 1.4 moles (in terms of titanium dioxide) of the titania sol dispersion, 1.1 times the molar amount of strontium chloride aqueous solution was added and placed in a reaction vessel, which was then purged with nitrogen gas. Furthermore, pure water was added to achieve a titanium dioxide concentration of 0.7 mol / L.

[0292] Next, the mixture was stirred and heated to 80°C. Then, while applying ultrasonic vibration, 500 mL of 20N sodium hydroxide aqueous solution was added over 5 minutes, and the reaction was carried out for 20 minutes. The slurry after the reaction was cooled to below 30°C over 1 hour, and the supernatant was removed. Furthermore, a pH 5.0 hydrochloric acid aqueous solution was added to the slurry and stirred for 1 hour to dissolve and remove strontium carbonate, and then the mixture was washed repeatedly with pure water.

[0293] Next, a pH 3.0 hydrochloric acid aqueous solution was added to the slurry, and then 2.0% by mass of n-octyltriethoxysilane relative to the solid content of the slurry was added and the mixture was stirred for 10 hours. After that, it was neutralized with an aqueous sodium hydroxide solution, filtered through a Nucche filter, and washed with pure water. The resulting cake was dried to obtain titanate compound fine particles 3. The physical properties are shown in Table 3.

[0294] <Example of manufacturing titanate compound fine particles 4> A hydrated titanium oxide slurry obtained by hydrolyzing an aqueous solution of titanyl sulfate was washed with an alkaline aqueous solution until the electrical conductivity of the supernatant reached 50 μS / cm, thereby reducing impurities and purifying the solution. Next, hydrochloric acid was added to the hydrated titanium oxide slurry to adjust the pH to 0.7 to obtain a titania sol dispersion.

[0295] To 2.6 moles (in terms of titanium dioxide) of the titania sol dispersion, 1.2 times the molar amount of strontium chloride aqueous solution was added and placed in a reaction vessel, which was then purged with nitrogen gas. Furthermore, pure water was added to achieve a titanium dioxide concentration of 1.3 mol / L.

[0296] Next, the mixture was stirred and heated to 95°C. Then, while applying ultrasonic vibration, 312 mL of 15N sodium hydroxide aqueous solution was added over 5 minutes, and the reaction was carried out for 20 minutes. After the reaction, 5°C pure water was added to the slurry and it was rapidly cooled to below 30°C, after which the supernatant was removed. Furthermore, a pH 5.0 hydrochloric acid aqueous solution was added to the slurry and stirred for 1 hour to dissolve and remove strontium carbonate, and then the mixture was washed repeatedly with pure water.

[0297] Next, an aqueous hydrochloric acid solution with a pH of 3.0 was added to the slurry, and then 5.0% by mass of isobutyltrimethoxysilane relative to the solid content of the slurry was added and the mixture was stirred for 10 hours. After that, it was neutralized with an aqueous sodium hydroxide solution, filtered through a Nucche filter, and washed with pure water. The resulting cake was dried to obtain titanate compound fine particles 4. The physical properties are shown in Table 3.

[0298] <Example of manufacturing titanate compound fine particles 5> A hydrated titanium oxide slurry obtained by hydrolyzing an aqueous solution of titanyl sulfate was washed with an alkaline aqueous solution until the electrical conductivity of the supernatant was 100 μS / cm to reduce impurities and purify the solution. Next, hydrochloric acid was added to the hydrated titanium oxide slurry to adjust the pH to 0.7 to obtain a titania sol dispersion.

[0299] To 0.6 moles (in terms of titanium dioxide) of the titania sol dispersion, 1.0 molar volume of strontium chloride aqueous solution was added and placed in a reaction vessel, which was then purged with nitrogen gas. Furthermore, pure water was added to achieve a titanium dioxide concentration of 0.3 mol / L.

[0300] Next, the mixture was stirred and heated to 70°C. Then, 750 mL of 2N sodium hydroxide aqueous solution was added over 120 minutes, and the reaction was carried out for 20 minutes. The slurry after the reaction was cooled to below 30°C over 1 hour, and the supernatant was removed. Furthermore, the slurry was washed with pure water and dried.

[0301] Next, the inorganic fine particles were placed in a sealed high-speed stirrer and stirred while purging with nitrogen. A treatment agent, prepared by diluting 2% by mass of dimethyl silicone oil with hexane 6.5 times relative to the solid content of the slurry, was sprayed into the stirrer. After spraying the entire amount of treatment agent, the temperature inside the stirrer was raised to 350°C while stirring, and the mixture was stirred for 3 hours. After the temperature inside the stirrer was returned to room temperature while stirring, the mixture was removed and crushed in a pin mill to obtain titanate compound fine particles 5. The physical properties are shown in Table 3.

[0302] <Example of manufacturing titanate compound fine particles 6> A hydrated titanium oxide slurry obtained by hydrolyzing an aqueous solution of titanyl sulfate was washed with an alkaline aqueous solution until the electrical conductivity of the supernatant was 100 μS / cm to reduce impurities and purify the solution. Next, hydrochloric acid was added to the hydrated titanium oxide slurry to adjust the pH to 0.7 to obtain a titania sol dispersion.

[0303] To 0.6 moles (in terms of titanium dioxide) of the titania sol dispersion, 1.0 molar volume of strontium chloride aqueous solution was added and placed in a reaction vessel, which was then purged with nitrogen gas. Furthermore, pure water was added to achieve a titanium dioxide concentration of 0.3 mol / L.

[0304] Next, the mixture was stirred and heated to 70°C. Then, 750 mL of 2N sodium hydroxide aqueous solution was added over 120 minutes, and the reaction was carried out for 20 minutes. The slurry after the reaction was cooled to below 30°C over 1 hour, and the supernatant was removed. Furthermore, the slurry was washed with pure water and dried.

[0305] Next, the inorganic fine particles were placed in a sealed high-speed stirrer and stirred while purging with nitrogen. A treatment agent, prepared by diluting 2% by mass of dimethyl silicone oil with hexane 6.5 times relative to the solid content of the slurry, was sprayed into the stirrer. After spraying the entire amount of treatment agent, the temperature inside the stirrer was raised to 350°C while stirring, and the mixture was stirred for 3 hours. The temperature inside the stirrer was returned to room temperature while stirring, and the mixture was removed to obtain titanate compound fine particles 6. The physical properties are shown in Table 3.

[0306] [Table 3]

[0307] <Example of Toner 1 manufacturing> • Binding resin 1 100 parts by mass Paraffin wax (melting point 78°C) 4 parts by mass CI Pigment Blue 15:3 4 parts by mass The above materials were pre-mixed using a Henschel mixer (product name: FM-10C, manufactured by Nippon Coke Co., Ltd.), and then melt-kneaded at 160°C using a twin-screw kneading extruder.

[0308] The resulting mixture was cooled, coarsely ground in a hammer mill, and then finely ground in a turbo mill.

[0309] The obtained finely ground material was classified using a multi-segment classifier utilizing the Coanda effect to obtain toner base particles 1 with a weight-average particle size (D4) of 6.5 μm.

[0310] (First external treatment) Next, silica fine particles 1 were added to the obtained toner matrix particles 1 as the first external addition treatment, as shown below.

[0311] Toner matrix particles 1:100 parts by mass • Silica fine particles 1:3.0 parts by mass The above ingredients were mixed using a Henschel mixer (product name: FM-10C, manufactured by Nippon Coke Co., Ltd.) at a rotation speed of 67 seconds. -1 The rotation speed was set to 4000 rpm, the rotation time to 2 minutes, and the heating temperature to room temperature.

[0312] (Surface treatment of toner particles) Subsequently, heat treatment was performed using the surface heat treatment apparatus shown in Figure 2, embedding a portion of the silica fine particles 1 into the toner matrix particle surface. The operating conditions of the surface heat treatment apparatus were: feed rate = 1.0 kg / hr, hot air temperature = 180°C, and hot air flow rate = 1.4 m³. 3 / min., cold air temperature E=3℃, cold air flow rate=1.2m 3 I set it to / min.

[0313] Next, using a wind-powered classifier utilizing the Coanda effect ("Elbow Jet Lab EJ-L3," manufactured by Nippon Steel Mining Co., Ltd.), fine and coarse powders were simultaneously classified and removed to obtain toner particles 1 in which silica fine particles 1 were embedded on the surface.

[0314] (Second external treatment) The heat-treated toner particles 1 obtained in this way were then subjected to a second external topping treatment, which involved adding silica fine particles, as described below. • Toner particles 1: 100 parts by mass • Silica fine particles 1: 2.0 parts by mass • Titanate compound fine particles 1: 1.2 parts by mass The above ingredients were mixed using a Henschel mixer (product name: FM-10C, manufactured by Nippon Coke Co., Ltd.) at a rotation speed of 67 seconds. -1 After mixing at room temperature with a rotation time of 2 minutes at 4000 rpm, the mixture was passed through an ultrasonic vibrating sieve with a mesh size of 54 μm to obtain toner 1. The embedding rate of silica nanoparticles in the obtained toner 1 is shown in Table 4.

[0315] <Manufacturing examples for toners 2-11> Toners 2-11 were obtained in the same manner as in the manufacturing example of toner 1, except that the first external additive treatment, surface treatment of toner particles, and second external additive treatment were performed using the formulations and conditions shown in Table 4. The embedding rates of silica microparticles in toners 2-6 are also shown in Table 4.

[0316] [Table 4]

[0317] <Example of manufacturing magnetic carrier core particle 1> Process 1 (Weighing and Mixing Process) Fe2O368.3% by mass MnCO328.5% by mass Mg(OH)22.0% by mass SrCO31.2% by mass The above ferrite raw materials were weighed, and 20 parts by mass of water were added to 80 parts by mass of the ferrite raw materials. Then, a slurry was prepared by wet mixing for 3 hours using a zirconia ball mill with a diameter (φ) of 10 mm. The solid content concentration of the slurry was 80% by mass.

[0318] Step 2 (Calibration Process) After drying the mixed slurry using a spray dryer (manufactured by Okawara Chemical Machinery Co., Ltd.), calcined ferrite was produced by firing it in a batch-type electric furnace under a nitrogen atmosphere (oxygen concentration 1.0 vol%) at a temperature of 1050°C for 3.0 hours.

[0319] Step 3 (Grinding Process) Calcined ferrite was crushed to approximately 0.5 mm using a crusher, and then water was added to prepare a slurry. The solid content concentration of the slurry was set to 70% by mass. This slurry was then ground for 3 hours in a wet ball mill using 1 / 8-inch stainless steel beads to obtain a slurry. This slurry was further ground for 4 hours in a wet bead mill using 1 mm diameter zirconia to obtain a calcined ferrite slurry with a volume-based 50% particle size (D50) of 1.3 μm.

[0320] Process 4 (granulation process) To 100 parts by mass of the above-mentioned calcined ferrite slurry, 1.0 part of ammonium polycarboxylate was added as a dispersant and 1.5 parts by mass of polyvinyl alcohol was added as a binder. The mixture was then granulated into spherical particles using a spray dryer (manufactured by Okawara Chemical Machinery Co., Ltd.) and dried. After adjusting the particle size of the resulting granules, the mixture was heated in a rotary electric furnace at 700°C for 2 hours to remove organic matter such as dispersants and binders.

[0321] Step 5 (Baking process) Under a nitrogen atmosphere (oxygen concentration 1.0 vol%), the temperature was raised from room temperature to the firing temperature (1100°C) in 2 hours, and then maintained at 1100°C for 4 hours for firing. After that, the temperature was lowered to 60°C over 8 hours, the atmosphere was changed from nitrogen to air, and the product was removed at a temperature of 40°C or lower.

[0322] Process 6 (Sorting Process) After crushing the aggregated particles, coarse particles were removed by sieving with a 150 μm mesh sieve, fine powder was removed by air classification, and low magnetic force components were further removed by magnetic separation to obtain porous magnetic core particles.

[0323] Process 7 (filling process) 100 parts by mass of porous magnetic core particles 1 were placed in the stirring container of a mixing and stirring machine (Dalton NDMV type universal stirring machine), and 5 parts dropwise were added a filling resin consisting of methyl silicone oligomer: 95.0% by mass and γ-aminopropyltrimethoxysilane: 5.0% by mass at atmospheric pressure while maintaining a temperature of 60°C.

[0324] After the dropping was complete, stirring was continued while adjusting the time, and the temperature was raised to 70°C to fill the particles of each porous magnetic core with the resin composition.

[0325] The resin-filled magnetic core particles obtained after cooling were transferred to a mixer with spiral blades (Drum Mixer UD-AT type, manufactured by Sugiyama Heavy Industries Co., Ltd.) in a rotatable mixing container, and the temperature was raised to 140°C at a heating rate of 2°C / min under a nitrogen atmosphere while stirring. Heating and stirring were then continued at 140°C for 50 minutes.

[0326] The ferrite particles were then cooled to room temperature, filled with resin, and hardened. Non-magnetic materials were removed using a magnetic separator. Coarse particles were then removed using a vibrating screen to obtain resin-filled magnetic carrier core particles 1.

[0327] (Examples of coating resin manufacturing) • Cyclohexyl methacrylate monomer 26.8% by mass • Methyl methacrylate monomer 0.2% by mass • Methyl methacrylate macromonomer 8.4% by mass (A macromonomer with a weight-average molecular weight of 5000, having a methacryloyl group at one end.) • Toluene 31.3% by mass • Methyl ethyl ketone 31.3% by mass • Azobisisobutyronitrile 2.0% by mass Of the above materials, cyclohexyl methacrylate monomer, methyl methacrylate monomer, methyl methacrylate macromonomer, toluene, and methyl ethyl ketone were placed in a four-necked separable flask equipped with a reflux condenser, thermometer, nitrogen inlet tube, and stirrer. After introducing nitrogen gas into the separable flask to create a sufficient nitrogen atmosphere, the mixture was heated to 80°C, azobisisobutyronitrile was added, and polymerization was carried out under reflux for 5 hours.

[0328] Hexane was injected into the resulting reactant to precipitate the copolymer.

[0329] The obtained precipitate was filtered off and then vacuum-dried to obtain a resin. 30 parts by mass of the resin was dissolved in a mixed solvent of 40 parts by mass of toluene and 30 parts by mass of methyl ethyl ketone to obtain a resin solution (solid content concentration 30%).

[0330] (Preparation of coating resin solution) ·Resin solution (solid content concentration 30%) 33.3% by mass • Toluene 66.4% by mass • Carbon black (Regal330; manufactured by Cabot) 0.3% by mass (Number-average particle size of primary particles: 25 nm, Nitrogen adsorption specific surface area: 94 m²) 2 / g, DBP oil absorption: 75ml / 100g) The above materials were placed in a paint shaker and dispersed for 1 hour using zirconia beads with a diameter of 0.5 mm. The resulting dispersion was filtered through a 5.0 μm membrane filter to obtain a coating resin solution.

[0331] <Manufacturing example of magnetic carrier 1> The above-mentioned coating resin solution and magnetic carrier core particles 1 were added to a vacuum-degassed kneader maintained at room temperature (the amount of coating resin solution added was 2.5 parts by mass of resin component per 100 parts by mass of magnetic carrier core particles 1).

[0332] After adding the solvent, the mixture was stirred at a rotation speed of 30 rpm for 15 minutes. Once a certain amount (80%) of the solvent had evaporated, the temperature was raised to 80°C while mixing under reduced pressure. Toluene was then removed by distillation over 2 hours, followed by cooling.

[0333] The obtained magnetic carriers were separated for low magnetic force by magnetic separation, passed through a sieve with an opening of 70 μm, and then classified using an air classifier to obtain magnetic carrier 1 with a 50% particle size (D50) of 38.2 μm based on volume distribution.

[0334] [Example 1] <Preparation of two-component developer 1> Toner 1 and magnetic carrier 1 were added to achieve a toner concentration of 8.0% by mass, and mixed using a V-type mixer (V-10 model: Tokuju Manufacturing Co., Ltd.) for 0.5 seconds. -1 Two-component developer 1 was prepared by mixing under conditions of a rotation time of 5 minutes.

[0335] <Rating> The following evaluations were performed using the obtained two-component developer 1 in the image forming apparatus described below. Two-component developer 1 received an A rating in all evaluations.

[0336] Using a modified Yanon imageRUNNER ADVANCE C5560 full-color copier as the image forming apparatus, the two-component developer 1 was placed in the cyan developer unit of the image forming apparatus, and toner 1 was filled into a cyan toner bottle for the evaluation described below.

[0337] The modifications included removing the mechanism that discharges excess magnetic carriers from inside the developer, and increasing the image formation speed from 60 A4 size images per minute to 80 images per minute. Additionally, the contact force of the cleaning blade against the photoreceptor was set to 0.245 N / cm.

[0338] The evaluation paper used is white paper (product name: CS-814 (A4, 81.4 g / m²)). 2 (Canon Marketing Japan Inc.) was used.

[0339] [Evaluation of damage to the photoreceptor] Using the image forming apparatus described above, 100,000 A4 landscape charts with a print density of 5% were printed intermittently in a 5-sheet pattern under conditions of 10°C and 5% RH. Subsequently, halftone images with a print density of 30% were printed. Meanwhile, scratches on the surface of the photoreceptor were visually observed to determine the presence of image defects originating from scratches on the photoreceptor. (Evaluation Criteria) A: Scratches on the photoreceptor are not showing up as image defects. B: Scratches on the photoreceptor are appearing as image defects.

[0340] [Evaluation of the Ghost that Accompanies External Additives] Using the image forming apparatus described above, 100,000 A4 landscape charts with a print density of 30% were continuously printed in a normal temperature and low humidity environment (temperature 23°C, humidity 5%RH). Subsequently, 100 images were printed at an image ratio of 10%, with vertical bands parallel to the paper feeding direction and white areas remaining outside the vertical bands. The vertical band areas are FFh images (solid images). After feeding 100 sheets, a full-screen halftone image (80h) was printed, and ghosting due to external additives was evaluated.

[0341] Using an X-Rite color reflectance densitometer (500 series: manufactured by X-Rite), the image density of the areas that produced vertical bands and the areas that produced white backgrounds in the halftone image was measured, and the ghosting associated with the external additive was evaluated from the difference Δ between the two image densities according to the following criteria. (Evaluation Criteria) A: Less than 0.03 B: 0.03 or higher, less than 0.06 C: 0.06 or higher and less than 0.11 D:0.11 or more

[0342] [Toner fusion] Using the image forming apparatus described above, 100,000 A4 landscape charts with a print density of 30% were continuously printed in a high-temperature, high-humidity environment (temperature 30°C, humidity 80%RH). Subsequently, an FFh image (solid image) was formed on the entire surface of the A4 evaluation paper, and the number of white dots that appeared on the solid image was visually evaluated. (Evaluation Criteria) A:0 pieces B: 1 or more but less than 5 C: 6 or more but less than 10 D: 10 or more

[0343] [Examples 2-7, Comparative Examples 1-4] <Preparation and evaluation of two-component developers 2-11> Two-component developers 2-11 were prepared in the same manner as two-component developer 1, except that toner 1 was replaced with toners 2-11.

[0344] Next, evaluation was carried out in the same manner as in Example 1, except that two-component developers 2 to 11 were used. The evaluation results are shown in Table 5.

[0345] [Table 5]

Claims

1. A toner having toner particles and an external additive on the surface of the toner particles, The external additive comprises silica microparticles and titanate compound microparticles. The silica nanoparticles are surface-treated silica nanoparticles, Solid silica fine particles 29 In Si-NMR DD / MAS measurements, the Si in the structure represented by the following formula (1) a Peak PD1, which corresponds to the silicon atom shown, and Si in the structure represented by the following formula (2) b A peak PD2 corresponding to the silicon atom shown is observed, and when the area of ​​peak PD1 is taken as SD1 and the area of ​​peak PD2 is taken as SD2, then SD1 and SD2 are 1.2≦(SD1+SD2) / SD1≦10.0 Satisfying the conditions, The number-average particle size of the primary particles of the titanate compound fine particles is 10 nm or more and 100 nm or less. A toner characterized in that the average circularity of the primary particles of the titanate compound fine particles is 0.700 or more and 1.00 or less. 【Chemistry 1】 (In the formula, R represents a hydrogen atom, a methyl group, or an ethyl group, independently.)

2. The toner according to claim 1, wherein (SD1 + SD2) / SD1 is 1.2 or more and 6.3 or less.

3. The toner according to claim 1, wherein (SD1 + SD2) / SD1 is 1.2 or more and 3.8 or less.

4. The toner according to claim 1, wherein (SD1 + SD2) / SD1 is 1.2 or more and 2.8 or less.

5. The solid silica fine particles 29 In Si-NMR DD / MAS measurements, the Si in the structure represented by the following formula (3) c A peak PQ corresponding to the silicon atom shown is observed, and when the area of ​​the peak PQ is denoted as SQ, then SD1, SD2 and SQ are, (SD1+SD2) / SQ×100≧1.0 The toner according to claim 1 or 2, satisfying the requirements. 【Chemistry 2】

6. The solid silica fine particles 29 Using SD1, SD2, and SQ obtained from Si-NMR DD / MAS measurements, the following equation is used: Ca=(SD1+SD2) / SQ×100 Ca calculated from, Solid silica fine particles after washing with hexane 29 Si in the structure represented by formula (1), obtained by DD / MAS measurement of Si-NMR a the area SD1w of the peak PD1w corresponding to the silicon atom represented by, and Si in the structure represented by formula (2) b the area SD2w of the peak PD2w corresponding to the silicon atom represented by, and Si in the structure represented by formula (3) c using the area SQw of the peak PQw corresponding to the silicon atom represented by, the following formula: Cb=(SD1w+SD2w) / SQw×100 The Cb calculated from this is (Ca-Cb) / Ca×100≦30 The toner according to claim 5 that satisfies the requirements.

7. The toner according to claim 1 or 2, wherein the number-average particle size of the primary particles of the silica fine particles is 5 nm or more and 500 nm or less.

8. The toner according to claim 1 or 2, wherein the content of the silica fine particles is 0.01 parts by mass or more and 10.00 parts by mass or less per 100 parts by mass of toner particles.

9. The toner according to claim 1 or 2, wherein the titanate compound fine particles have a number-average particle size of 10 nm or more and 70 nm or less, and an average circularity of 0.800 or more and 0.900 or less.

10. The toner according to claim 1 or 2, wherein the titanate compound fine particles are strontium titanate particles or calcium titanate particles.

11. The toner according to claim 1 or 2, wherein the content of the titanate compound fine particles is 0.05 parts by mass or more and 2.0 parts by mass or less per 100 parts by mass of toner particles.

12. The number-average particle size A of the silica fine particles is, relative to the number-average particle size B of the titanate compound fine particles, A > B The toner according to claim 1 or 2.

13. The aforementioned silica fine particles have a BET specific surface area of ​​1 m² at a temperature of 30°C and a relative humidity of 80%. 2 The amount of water absorbed per unit is 0.01 cm 3 / m 2 0.1cm or more 3 / m 2 The toner according to claim 1 or 2, which is as follows:

14. The solid silica fine particles 29 In Si-NMR DD / MAS measurements, the Si in the structure represented by the following formula (3) c A peak PQ corresponding to the silicon atom shown is observed, and when the area of ​​the peak PQ is denoted as SQ, then SD1, SD2 and SQ are, (SD1+SD2) / SQ×100≧1.0 Satisfying the conditions, The solid silica fine particles 29 Using SD1, SD2, and SQ obtained from Si-NMR DD / MAS measurements, the following equation is used: Ca=(SD1+SD2) / SQ×100 Ca calculated from, Solid silica microparticles after washing with hexane 29 Si in the structure represented by formula (1), obtained from DD / MAS measurement of Si-NMR a The area SD1w of the peak PD1w corresponding to the silicon atom shown, and the Si in the structure represented by formula (2) above. b The area SD2w of the peak PD2w corresponding to the silicon atom shown, and the Si in the structure represented by formula (3). c Using the area SQw of the peak PQw corresponding to the silicon atom shown, the following equation is used: Cb=(SD1w+SD2w) / SQw×100 The Cb calculated from this is (Ca-Cb) / Ca×100≦30 Satisfying the conditions, The aforementioned silica fine particles have a BET specific surface area of ​​1 m² at a temperature of 30°C and a relative humidity of 80%. 2 The amount of water absorbed per unit is 0.01 cm 3 / m 2 0.1cm or more 3 / m 2 The toner according to claim 1 or 2, which is as follows: 【Transformation 3】

15. An image forming method comprising: a charging step of charging the surface of a photoreceptor; an electrostatic latent image forming step of forming an electrostatic latent image on the charged photoreceptor; a developing step of developing the electrostatic latent image with toner to form a toner image on the surface of the photoreceptor; a transfer step of transferring the toner image to a recording medium; a fixing step of fixing the toner image on the recording medium; and a cleaning step of bringing a cleaning blade into contact with the photoreceptor to remove residual toner on the photoreceptor, The toner is a toner having toner particles and an external additive on the surface of the toner particles, The external additive comprises silica microparticles and titanate compound microparticles. The silica nanoparticles are surface-treated silica nanoparticles, Solid silica fine particles 29 In Si-NMR DD / MAS measurements, the Si in the structure represented by the following formula (1) a Peak PD1, which corresponds to the silicon atom shown, and Si in the structure represented by the following formula (2) b A peak PD2 corresponding to the silicon atom shown is observed, and when the area of ​​peak PD1 is taken as SD1 and the area of ​​peak PD2 is taken as SD2, then SD1 and SD2 are 1.2≦(SD1+SD2) / SD1≦10.0 Satisfying the conditions, The number-average particle size of the primary particles of the titanate compound fine particles is 10 nm or more and 100 nm or less. An image forming method characterized in that the average circularity of the primary particles of the titanate compound fine particles is 0.700 or more and 1.00 or less. 【Chemistry 4】 (In the formula, R represents a hydrogen atom, a methyl group, or an ethyl group, independently.)

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