Toner

Abstract

To provide a toner in which image failure due to detachment of silica aggregate particles is unlikely to occur even when used for a long term under a low temperature low humidity environment.SOLUTION: A toner has toner particles containing binder resin and silica aggregate particles, where boron atom deriving peak of the toner particles and peak derived from a boron-oxygen structure are detected. The silica aggregate particles are an aggregate of silica microparticles whose primary particle diameter of a number reference is between 20 nm and 75 nm. A largest Ferret diameter of the silica aggregate particle is between 110 nm and 500 nm, and its aspect ratio is between 1.50 and 4.00. When the silica aggregate particles are scattered in solvent and titration operation using NaOH solution is performed, the following formula (1) is satisfied: 0.01≤{(a-b)×c×NA} / (d×e)≤0.20...(1).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a toner used in an electrophotographic image forming apparatus. [Background technology]

[0002] In general, electrophotography involves forming a latent image on an image carrier (photoreceptor) using a photoconductive substance, developing the electrostatic latent image with toner to make it visible, transferring the toner image on the photoreceptor to a recording medium such as paper as necessary, and then fixing the toner image on the recording medium by heat, pressure, heat and pressure, etc., to obtain a copy or print. In this case, any toner remaining on the photoreceptor after transfer that has not been transferred to the recording medium is cleaned by various methods. In the above-mentioned transfer process for transferring the toner image on the photoreceptor to the recording medium, a contact transfer method has been proposed in which the toner image on the photoreceptor is pressed against the recording medium to transfer the toner image. In this contact transfer method, in order to faithfully transfer the toner image on the photoreceptor to the recording medium, it is important to appropriately charge the toner and to suppress a decrease in the fluidity of the toner. That is, in the transfer nip where the photoconductor and transfer member come into contact in the contact transfer method, when the toner image on the photoconductor is pressed by the transfer member, the toner tends to adhere to the photoconductor, and if the adhesion is strong, image defects may occur. The above image defects are noticeable in line images, and are called "transfer defects" because part of the line is missing (mainly the center), and they are a challenge in improving image quality. Additionally, in recent years, printers have begun to be used in places other than normal office environments, and there is an increasing demand for printers to be able to continue providing high-quality images in harsh environments until the end of their product life, i.e., for printers to have a longer life. In order to satisfy these demands, a toner is required to have durability that enables high-quality images to be output even when used for a long period of time. Conventionally, toners in which aggregated silica fine particles (hereinafter referred to as silica aggregate particles) are added to toner particles have been studied for the purpose of improving durability. Silica aggregate particles can reduce adhesion to various members with a small amount of addition due to the spacer effect. In addition, since silica aggregate particles have unevenness, they are less likely to be embedded in toner particles than non-aggregated silica fine particles, and durability can be improved. On the other hand, when silica aggregate particles are added, they may detach from the surface of the toner particles when the toner is rubbed, and the concentration of silica aggregate particles may increase in the storage container when used for a long period of time. In particular, the above phenomenon becomes prominent when used for a long period of time in a low temperature and low humidity environment (15°C, 10%) in which embedding of external additives is easily suppressed. When the concentration of silica aggregate particles increases in the storage container due to the detachment of silica aggregate particles, the flowability of the toner decreases because the silica aggregate particles have low rolling properties on the surface of the toner particles. As a result, when a toner containing silica aggregate particles is used for a long period of time in a low temperature and low humidity environment, although durability is improved, the detachment of silica aggregate particles causes transfer voids to worsen. Therefore, toners in which the moisture adsorption amount and shape of silica agglomerated particles are improved have been studied as a method for improving the suppression of transfer voids in toners containing silica agglomerated particles. Patent Document 1 proposes a toner to which silica agglomerated particles with an optimized pore volume are added for the purpose of adjusting the moisture adsorption amount. Patent Document 2 proposes a toner to which silica agglomerated particles with an optimized shape are added for the purpose of suppressing rolling on the toner particle surface. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-1721 A [Patent Document 2] JP 2018-45112 A Summary of the Invention [Problem to be solved by the invention]

[0004] As a result of the inventors' investigation, it is believed that the toner described in Patent Document 1 increases the adhesion to the toner in a low-temperature, low-humidity environment by adding silica agglomerated particles with an optimized pore volume. However, the inventors' investigation revealed that when the toner is used in a low-temperature, low-humidity environment for a long period of time, the detachment of the silica agglomerated particles cannot be sufficiently suppressed. As a result, the concentration of the silica agglomerated particles increases in the storage container, and the fluidity of the toner decreases. In other words, it was found that there is a problem with transfer defects caused by the detachment of the silica agglomerated particles when the toner is used in a low-temperature, low-humidity environment for a long period of time. On the other hand, the toner described in Patent Document 2 is thought to increase the adhesion to the toner by optimizing the shape. However, as in Patent Document 1, it was found that when the toner is used for a long period of time in a low-temperature, low-humidity environment, the detachment of silica aggregated particles cannot be sufficiently suppressed. As a result, the concentration of silica aggregated particles increases in the storage container, and the fluidity of the toner decreases. In other words, it was found that there is a problem with transfer defects caused by the detachment of silica aggregated particles when used for a long period of time in a low-temperature, low-humidity environment. Therefore, an object of the present invention is to provide a toner which is less susceptible to image defects caused by detachment of silica aggregated particles even when used for a long period of time in a low-temperature, low-humidity environment. [Means for solving the problem]

[0005] The present invention provides a toner having toner particles containing a binder resin and silica aggregate particles, In a TOF-SIMS measurement of the toner particles, a fragment peak derived from a boron atom and a fragment peak derived from a boron-oxygen structure are detected, The silica agglomerated particles are agglomerates of silica fine particles having a number-based primary particle size of 20 nm or more and 75 nm or less, The maximum Feret diameter of the silica agglomerated particles is 110 nm or more and 500 nm or less, the aspect ratio of the silica agglomerated particles is 1.50 or more and 4.00 or less; The toner is characterized in that when the silica aggregate particles are dispersed in a solvent and titrated with an aqueous NaOH solution, the following formula (1) is satisfied: 0.01≦{(ab)×c×NA} / (d×e)≦0.20···(1) (In formula (1), a is the titration amount (L) of NaOH aqueous solution required to adjust a mixture of 25.0 g of ethanol in which silica agglomerated particles are dispersed and 75.0 g of 20 mass % NaCl aqueous solution to pH 9. b is the titer (L) of NaOH solution required to adjust a mixture of 25.0 g of ethanol and 75.0 g of 20% NaCl solution to pH 9. c is the concentration (N) of the NaOH aqueous solution used in the titration. NA is Avogadro's number. d is the mass of the silica agglomerated particles (g). e is the BET specific surface area (nm 2 / g). Effect of the Invention

[0006] According to the present invention, it is possible to provide a toner which is less susceptible to image defects caused by detachment of silica aggregated particles even when used for a long period of time in a low-temperature, low-humidity environment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The expressions "xx or more and xx or less" or "xx to xx" expressing a numerical range mean a numerical range including the endpoints, that is, the lower limit and the upper limit, unless otherwise specified.

[0008] [Background to the invention] The present inventors have conducted extensive research into a toner containing silica agglomerated particles that can suppress detachment of silica agglomerated particles and continue to provide high-quality images even when images are output for a long period of time in a low-temperature, low-humidity environment.

[0009] To date, toners in which the moisture adsorption amount and shape of silica agglomerated particles have been optimized have been studied as an approach to suppress the detachment of silica agglomerated particles from toner particles. By optimizing the moisture adsorption amount of silica agglomerated particles, it is possible to increase the adhesion force to toner particles and suppress the detachment of silica agglomerated particles. In addition, by optimizing the shape of silica agglomerated particles, it is possible to increase the adhesion force to toner particles and suppress the detachment of silica agglomerated particles.

[0010] However, when considering the detachment of silica agglomerated particles when image output is performed for a long period of time in a low-temperature, low-humidity environment, the silica agglomerated particles may detach when the toner is rubbed. In particular, silica agglomerated particles with a large particle size form a convex portion on the toner particle surface, and the convex height from the toner particle surface becomes high, so that they tend to detach when the toner is rubbed. As a result, when image output is performed for a long period of time in a low-temperature, low-humidity environment, the silica agglomerated particles detach, and the concentration of the silica agglomerated particles increases in the storage container. When the concentration of the silica agglomerated particles in the storage container increases, the silica agglomerated particles have low rolling properties on the toner particle surface, so the fluidity of the toner decreases. When the toner with reduced fluidity is pressed against the toner image on the photoconductor by the transfer member at the transfer nip portion where the photoconductor and the transfer member are in contact with each other, the toner is easily brought into contact with the photoconductor, causing a transfer omission.

[0011] In other words, in the toners to which silica agglomerated particles are added as shown in Patent Documents 1 and 2, the silica agglomerated particles do not adhere sufficiently to the toner particle surface, and therefore, when the toner is used for a long period of time in a low-temperature, low-humidity environment, the silica agglomerated particles are detached, resulting in transfer defects.

[0012] As a result of intensive research, the present inventors have found that, with a toner containing silica aggregated particles, the following configuration makes it possible to continue to provide high-quality images even when image output is performed for a long period of time in a low-temperature, low-humidity environment.

[0013] That is, the toner of the present invention is a toner having toner particles containing a binder resin and silica aggregate particles, In a TOF-SIMS measurement of the toner particles, a fragment peak derived from a boron atom and a fragment peak derived from a boron-oxygen structure are detected, The silica agglomerated particles are agglomerates of silica fine particles having a number-based primary particle size of 20 nm or more and 75 nm or less, The maximum Feret diameter of the silica agglomerated particles is 110 nm or more and 500 nm or less, the aspect ratio of the silica agglomerated particles is 1.50 or more and 4.00 or less; The silica agglomerated particles are characterized in that when dispersed in a solvent and titrated with an aqueous NaOH solution, the following formula (1) is satisfied. 0.01≦{(ab)×c×NA} / (d×e)≦0.20···(1) (In formula (1), a is the titration amount (L) of NaOH aqueous solution required to adjust a mixture of 25.0 g of ethanol in which silica agglomerated particles are dispersed and 75.0 g of 20 mass % NaCl aqueous solution to pH 9. b is the titer (L) of NaOH solution required to adjust a mixture of 25.0 g of ethanol and 75.0 g of 20% NaCl solution to pH 9. c is the concentration (N) of the NaOH aqueous solution used in the titration. NA is Avogadro's number. d is the mass of the silica agglomerated particles (g). e is the BET specific surface area (nm 2 / g).

[0014] [Mechanism by which the present invention exerts its effects] The reason why the above-mentioned performance can be imparted by combining toner particles having boron-oxygen bonds (BO bonds) on the toner surface layer with silica aggregate particles in which the primary particle size, maximum Feret diameter, aspect ratio, and silanol content are controlled will be described.

[0015] The present inventors have found that in a toner containing silica aggregated particles, the following points are important in order to suppress detachment from the toner particles when the toner is used for a long period of time in a low-temperature, low-humidity environment. (1-1) An electrostatic interaction occurs between the silanol groups of the silica agglomerated particles and the surfaces of the toner particles, improving the adhesion of the silica agglomerated particles. (1-2) The silica agglomerated particles have a flat shape, and the contact area with the toner particle surface is increased, thereby improving the adhesion of the silica agglomerated particles.

[0016] The above (1-1) is strongly influenced by the amount of silanol in the silica agglomerated particles and the BO bonds in the toner surface layer. The silanol in the silica agglomerated particles is a basic substance and has polarity. In addition, the BO bonds in the toner surface layer have polarity due to polarization. For this reason, electrostatic interaction occurs between the silanol in the silica agglomerated particles and the BO bonds in the toner particle surface layer. As a result, the adhesion of the silica agglomerated particles is increased and the detachment of the silica agglomerated particles can be suppressed, so that transfer defects are less likely to occur even when image output is performed for a long period of time in a low-temperature, low-humidity environment.

[0017] On the other hand, the above (1-2) is strongly influenced by the primary particle size, maximum Feret's diameter, and aspect ratio of the silica agglomerated particles. Among these, the aspect ratio has a large effect, and by controlling the aspect ratio of the silica agglomerated particles to be high, the silica agglomerated particles can be made flat. As a result, the contact area with the toner particle surface increases, and the adhesion to the toner particles can be improved. In addition, by increasing the contact area between the silica agglomerated particles and the toner particle surface, it is expected that the electrostatic interaction acting between the silica agglomerated particles of the above (1-1) and the toner particle surface will be improved. Therefore, even if image output is performed for a long time in a low temperature and low humidity environment, transfer voids are less likely to occur.

[0018] As described above, only when the above (1-1) and (1-2) are satisfied can image defects caused by detachment of silica aggregated particles be suppressed even when image output is performed for a long period of time in a low-temperature, low-humidity environment.

[0019] [Configuration of the present invention] Specifically, in order to develop electrostatic interaction between the silica agglomerated particles and the BO bonds contained in the toner surface layer, it is necessary to satisfy the following points. That is, in a TOF-SIMS measurement of the toner particles, a fragment peak derived from a boron atom and a fragment peak derived from a BO structure must be detected, and when the silica agglomerated particles are titrated with an aqueous NaOH solution, the silanol amount defined by the following formula (1) must satisfy formula (1). When the silica agglomerated particles are titrated with an aqueous NaOH solution, the silanol amount defined by the following formula (1) must be 0.07 or more and 0.15 or less. 0.01≦{(ab)×c×NA} / (d×e)≦0.20···(1) (In formula (1), a is the titration amount (L) of NaOH aqueous solution required to adjust a mixture of 25.0 g of ethanol in which silica agglomerated particles are dispersed and 75.0 g of 20 mass % NaCl aqueous solution to pH 9. b is the titer (L) of NaOH solution required to adjust a mixture of 25.0 g of ethanol and 75.0 g of 20% NaCl solution to pH 9. c is the concentration (N) of the NaOH aqueous solution used in the titration. NA is Avogadro's number. d is the mass of the silica agglomerated particles (g). e is the BET specific surface area (nm 2 / g).

[0020] TOF-SIMS can qualitatively measure the surface area of ​​the toner below 10 nm. The presence or absence of BO bonds is measured by TOF-SIMS using sodium tetraborate decahydrate manufactured by Fujifilm Wako Pure Chemical Industries, Ltd. as a standard sample. The peak positions of boron atoms and BO2 (a typical structure with BO bonds) are confirmed for the measurement data. Then, the presence or absence of boron atoms and BO bonds can be known by performing TOF-SIMS measurement of the target toner. If there are peaks of boron atoms and BO bonds, electrostatic interactions can be made to function with the silanol of the silica aggregated particles. Therefore, even when used for a long period of time in a low-temperature, low-humidity environment, it is possible to suppress transfer defects caused by detachment of silica aggregated particles.

[0021] The means for incorporating BO bonds in the surface layer of toner particles is not particularly limited, but for example, boric acid can be incorporated into the toner particles by adding it internally to the toner particles or using it as an aggregating agent in the aggregation method. Adding boric acid as an aggregating agent makes it easier to introduce boric acid near the surface of the toner particles. At the stage of using it as a raw material, it may be used in the form of organic boric acid, boric acid salt, boric acid ester, etc. When the toner particles are produced in an aqueous medium, it is preferable to add it as a boric acid salt from the viewpoint of reactivity and production stability, and specifically, for example, sodium tetraborate, ammonium borate, etc. can be mentioned, and in particular, borax is preferably used.

[0022] Borax is represented by the decahydrate of sodium tetraborate (Na2B4O7) and changes to boric acid in an acidic aqueous solution, so borax is preferably used when used in an aqueous medium under an acidic environment.

[0023] The amount of silanol in the silica agglomerated particles being within the range of the above formula (1) means that although the amount of silanol on the surface of the silica agglomerated particles is small, a small amount of silanol remains. Therefore, while the silica agglomerated particles are hydrophobic, electrostatic interaction occurs between the remaining silanol and the BO bond contained in the toner particle surface. Therefore, even when used for a long period of time in a low temperature and low humidity environment, detachment of the silica agglomerated particles can be suppressed, and transfer defects can be suppressed.

[0024] When the silanol content of the silica agglomerated particles is less than 0.01 as defined by the above formula (1), the amount of silanol remaining on the surfaces of the silica agglomerated particles is too small, which reduces the electrostatic interaction with the boron on the toner particle surfaces. As a result, the adhesion of the silica agglomerated particles to the toner particles is reduced, which worsens the suppression of transfer defects.

[0025] When the amount of silanol in the silica agglomerated particles, as defined by the above formula (1), is greater than 0.20, the amount of silanol remaining on the surfaces of the silica agglomerated particles becomes excessive, which reduces the hydrophobicity of the silica agglomerated particles and tends to result in excessive charging. A toner containing such silica agglomerated particles is prone to triboelectric charging due to the stirring blades in the storage container, and tends to undergo electrostatic aggregation due to mirror force, resulting in a broad charge distribution. As a result, the suppression of fog, in which the toner is developed in the white parts of a recording medium in a low-temperature, low-humidity environment, becomes poor.

[0026] The amount of silanol on the surface of silica agglomerated particles can be controlled by the type of treatment agent used for hydrophobizing the surface of the silica agglomerated particles, the amount of the treatment agent, and the treatment temperature and treatment time during the hydrophobization treatment. The amount of silanol on the surface of silica agglomerated particles can also be controlled by the ratio of hydrogen gas concentration and oxygen gas concentration to silicon tetrachloride in the flame hydrolysis step described in the method for producing silica agglomerated particles described later. That is, by increasing the ratio of hydrogen gas concentration and oxygen gas concentration to silicon tetrachloride in the flame hydrolysis step, the hydrolysis of silicon tetrachloride can be completed. As a result, even when the surface of the silica agglomerated particles is hydrophobized, a small amount of silanol can be left behind.

[0027] The silica agglomerated particles are agglomerates of silica fine particles having a primary particle size based on number of 20 nm or more and 75 nm or less.

[0028] The fact that the primary particle diameter based on the number of silica agglomerated particles is within the above range means that the primary particle diameter of the silica fine particles constituting the silica agglomerated particles is large and the number of silica fine particles constituting the silica agglomerated particles is small. By reducing the number of silica fine particles constituting the silica agglomerated particles, the number of junctions of the silica fine particles contained in the silica agglomerated particles can be reduced. This improves the impact resistance of the silica agglomerated particles, and prevents the silica agglomerated particles from cracking even when the toner is rubbed by a stirring blade in a storage container. This prevents the silica agglomerated particles from embedding even when used for a long period of time in a low-temperature, low-humidity environment, improving the prevention of transfer defects.

[0029] When the primary particle size based on the number of silica agglomerated particles is less than 20 nm, the number of silica fine particles constituting the silica agglomerated particles becomes excessive, so that the silica agglomerated particles are likely to break when the toner is rubbed by the stirring blade in the storage container, etc. When a toner containing such silica agglomerated particles is used for a long period of time in a low-temperature, low-humidity environment, the silica agglomerated particles become embedded, and the suppression of transfer defects becomes worse.

[0030] When the number-based primary particle size of the silica agglomerated particles is larger than 75 nm, the number of silica fine particles constituting the silica agglomerated particles becomes too small, making it difficult to control the silica agglomerated particles to have a flat shape. In a toner containing such silica agglomerated particles, the adhesion of the silica agglomerated particles to the toner particles is reduced. As a result, when used for a long period of time in a low-temperature, low-humidity environment, the suppression of transfer defects caused by the detachment of the silica agglomerated particles is deteriorated.

[0031] The silica agglomerated particles must also have a maximum Feret's diameter of 110 nm or more and 500 nm or less, and preferably 120 nm or more and 400 nm or less.

[0032] The maximum Feret diameter of the silica agglomerated particles being in the above range means that the particle diameter of the silica agglomerated particles is appropriately large. The toner containing the silica agglomerated particles having the maximum Feret diameter in the above range can reduce the adhesion of the toner to various members due to the spacer effect. In addition, since the height of the convex formed when the silica agglomerated particles are fixed to the toner particle surface can be suppressed, the transfer void caused by the detachment of the silica agglomerated particles can be suppressed even when the toner is used for a long period of time in a low temperature and low humidity environment.

[0033] When the maximum Feret diameter of the silica agglomerated particles is less than 110 nm, the silica agglomerated particles become embedded when the toner is used for a long period of time in a low-temperature, low-humidity environment. When the toner containing such silica agglomerated particles is used for a long period of time in a low-temperature, low-humidity environment, when the toner is pressed against the photoconductor in the transfer nip, part of the toner adheres to the photoconductor, which deteriorates the suppression of transfer defects.

[0034] When the maximum Feret diameter of silica agglomerated particles is larger than 500 nm, the height of the convexity formed when the silica agglomerated particles adhere to the toner particle surface becomes high, and the silica agglomerated particles are detached when the toner is rubbed in a container. When a toner containing such silica agglomerated particles is used for a long period of time in a low-temperature, low-humidity environment, the suppression of transfer defects caused by the detachment of the silica agglomerated particles is deteriorated.

[0035] Furthermore, the silica aggregate particles must have an aspect ratio of 1.50 or more and 4.00 or less, and preferably 1.70 or more and 3.85 or less.

[0036] The aspect ratio of the silica aggregated particles in the above range means that the silica aggregated particles have a flat shape. This increases the contact area between the silica aggregated particles and the toner particles. In addition, the height of the convexity formed when the silica aggregated particles are fixed to the toner particle surface can be suppressed, so that the transfer void caused by the detachment of the silica aggregated particles can be suppressed when the silica aggregated particles are used for a long period of time in a low temperature and low humidity environment.

[0037] When the aspect ratio of the silica agglomerated particles is less than 1.50, the silica agglomerated particles become nearly spherical, so that the contact area between the silica agglomerated particles and the toner particles decreases. When a toner containing such silica agglomerated particles is used for a long period of time in a low-temperature, low-humidity environment, the suppression of transfer defects caused by the detachment of the silica agglomerated particles becomes poor.

[0038] When the aspect ratio of the silica agglomerated particles is greater than 4.00, the silica agglomerated particles have a rod-like shape, so that the silica agglomerated particles cover the surface of the toner particles. A toner containing such silica agglomerated particles is prone to excessive charging on the toner particle surface, electrostatic aggregation due to mirror force, and a broad charge distribution. As a result, the suppression of fog, in which the toner is developed in the white parts of a recording medium in a low-temperature, low-humidity environment, is deteriorated.

[0039] The toner of the present invention preferably has an abundance (by mass) of boron atoms in the toner measured by an inductively coupled plasma mass spectrometer (ICP-MS) of 0.01 ppm or more and 2.00 ppm or less, and more preferably 0.05 ppm or more and 1.50 ppm or less.

[0040] By controlling the amount of boron atoms present on the toner particle surface within the above range, the effect of electrostatic interaction with the silanol of the silica agglomerated particles is enhanced. This improves the adhesion of the silica agglomerated particles to the toner particles. As a result, even when used for a long period of time in a low-temperature, low-humidity environment, it is possible to suppress transfer defects caused by detachment of the silica agglomerated particles. A specific measurement method using the above device will be described later.

[0041] In the present invention, the coverage of the silica aggregate particles with respect to the toner particles is preferably 0.5% or more and 10.0% or less.

[0042] By controlling the coverage rate of the silica aggregated particles within the above range, the adhesive force to various members can be reduced by the spacer effect. In addition, the decrease in toner fluidity caused by the silica aggregated particles can be suppressed. Therefore, even when used for a long period of time in a low-temperature, low-humidity environment, the deterioration of the toner can be suppressed, and the transfer void can be suppressed.

[0043] In the present invention, the dispersion evaluation index of the silica agglomerated particles on the surface of the toner particles is preferably 2.00 or less. When the dispersion evaluation index is within the above range, it indicates that the silica agglomerated particles are uniformly dispersed on the surface of the toner particles. As a result, the silica agglomerated particles on the surface of the toner particles can reduce the adhesion to various members without increasing the amount of silica agglomerated particles added. Therefore, even when used for a long period of time in a low-temperature, low-humidity environment, it is possible to suppress toner deterioration and improve the suppression of transfer defects.

[0044] The coverage rate and dispersibility evaluation index of the silica agglomerated particles can be controlled by the production conditions in the external addition step, the type of the silica agglomerated particles, and the amount of the silica agglomerated particles added.

[0045] In the present invention, when the amount of boron atoms present in the toner is B (ppm), and the amount of silanol defined by the following formula (2) when the silica aggregated particles are dispersed in a solvent and titrated with an aqueous NaOH solution is S, it is preferable that B and S satisfy the following formula (3). S={(ab)×c×NA} / (d×e)···(2) 0.03≦S / B≦20.0 (3) (In formula (2), a is the titration amount (L) of NaOH aqueous solution required to adjust a mixture of 25.0 g of ethanol in which silica agglomerated particles are dispersed and 75.0 g of 20 mass % NaCl aqueous solution to pH 9. b is the titer (L) of NaOH solution required to adjust a mixture of 25.0 g of ethanol and 75.0 g of 20% NaCl solution to pH 9. c is the concentration (N) of the NaOH aqueous solution used in the titration. NA is Avogadro's number. d is the mass of the silica agglomerated particles (g). e is the BET specific surface area (nm 2 / g).

[0046] The S / B defined by the above formula (3) is more preferably 0.03 or more and 15.0 or less, and further preferably 0.05 or more and 3.00 or less.

[0047] By setting the S / B ratio defined by the above formula (3) within the above range, the effect of electrostatic interaction between the silica agglomerated particles and the toner particles can be enhanced. This makes it possible to enhance the adhesion of the silica agglomerated particles to the toner particle surface when the silica agglomerated particles are added. Therefore, even when used for a long period of time in a low-temperature, low-humidity environment, it is possible to suppress transfer defects caused by the detachment of the silica agglomerated particles.

[0048] The toner of the present invention preferably contains, in addition to the silica aggregate particles, titanium oxide particles that satisfy the following (i) and (ii): (i) the major axis is 300 nm or more and 3000 nm or less; (ii) Aspect ratio is 5.0 or more

[0049] Titanium oxide particles that satisfy the above (i) and (ii) are classified as external additives with large particle size and low resistance, and have a needle-like structure. The use of titanium oxide particles suppresses overcharging in low-temperature, low-humidity environments, and also adheres to the toner particle surface, suppressing the embedding of silica aggregate particles through the spacer effect. This reduces the change in fluidity during long-term use, thereby suppressing toner deterioration and improving the suppression of transfer defects even when used for long periods in low-temperature, low-humidity environments.

[0050] The content of the titanium oxide particles in the toner is preferably 0.1 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the toner. The lower limit is more preferably 0.5 parts by mass or more. The upper limit is more preferably 8.0 parts by mass or less.

[0051] The titanium oxide particles are not particularly limited as long as they satisfy the above (i) and (ii). For example, rutile type titanium oxide particles are one of the preferred forms.

[0052] It is also preferable to use titanium oxide particles B, which do not fall under the above-mentioned titanium oxide particles, in combination, since this makes it easier to suppress changes in the charge amount. The titanium oxide particles B have a particle diameter on the toner surface of 20 nm or more and 250 nm or less.

[0053] In the present invention, the average circularity of the toner is preferably 0.960 or more and 0.990 or less. When the average circularity of the toner is 0.960 or more, the shape of the toner becomes spherical or close to spherical, and the toner has excellent fluidity. Therefore, even when the toner is used for a long period of time in a low-temperature, low-humidity environment, it is possible to suppress transfer defects due to a decrease in fluidity.

[0054] It is preferable that the toner of the present invention has a shell layer on the surface of a toner particle, the shell layer present on the surface of the toner particle contains a polyester resin, the shell layer does not contain a crystalline material in a cross section of the toner observed with a transmission electron microscope, and when the thickness of the shell layer is T (nm), the following formula (4) is satisfied. 300≦T≦700 (4)

[0055] Toner particles with a polyester resin shell layer have polarity even in areas of the toner particle surface other than the BO structure, which enhances the effect of electrostatic interaction with the silanol of the silica aggregate particles. In addition, since the shell layer does not contain a crystalline material and satisfies the above formula (4), it is possible to suppress transfer defects even when used for a long period of time in a low-temperature, low-humidity environment.

[0056] The toner of the present invention preferably contains dodecylbenzenesulfonic acid or a dodecylbenzenesulfonate salt.

[0057] The BO bond present on the toner surface is a functional group that has high moisture adsorption properties, and is considered to retain moisture to a certain extent on the toner surface even in a low moisture environment such as a low temperature and low humidity environment. Furthermore, since dodecylbenzenesulfonic acid or dodecylbenzenesulfonate salts are water-soluble, they migrate into the moisture retained on the toner surface and become mobile on the toner surface containing moisture. Then, the sulfonic acid moiety in the dodecylbenzenesulfonic acid structure and the silanol group on the surface of the silica aggregated particles having the other polarity of the present invention are electrostatically adsorbed. As a result, it is considered that the excess charge of the silica is easily leaked into the surrounding moisture through the dodecylbenzenesulfonic acid or dodecylbenzenesulfonate salts, and overcharging can be suppressed.

[0058] The measurement of dodecylbenzenesulfonic acid will be described in detail later, but the ESI-MS measurement makes it possible to know whether or not dodecylbenzenesulfonic acid is present in the vicinity of the surface, and further, the amount of dodecylbenzenesulfonic acid contained in the toner.

[0059] [Toner components] <Silica agglomerated particles> The silica aggregate particles used in the toner of the present invention will be described below.

[0060] (Original substance) The raw material of the silica aggregate particles used in the present invention includes both dry silica, called dry method or fumed silica, produced by vapor phase oxidation of silicon halogen compounds, and wet silica produced from water glass, etc. In the present invention, dry silica, which has few silanol groups on the surface and inside and leaves no production residue, is preferred.

[0061] The dry method, for example, utilizes the thermal decomposition oxidation reaction of silicon tetrachloride gas in an oxyhydrogen flame, and the basic reaction formula is as follows: Specifically, the raw material silicon compound gas is introduced into the mixing chamber of a combustion burner together with an inert gas, mixed with hydrogen and air to obtain a mixed gas of a predetermined ratio, and this mixed gas is burned in the reaction chamber at a temperature of 1000 to 3000°C to generate silica, and after cooling, the generated silica is collected with a filter to obtain the raw material of silica aggregate particles. SiCl4+2H2+O2→SiO2+4HCl

[0062] In the above-mentioned manufacturing method, the temperature in the reaction chamber is maintained at or above the melting point of silica, and the raw silicon compound is retained in the reaction chamber, whereby the silica agglomerated particles are grown, and raw materials of silica agglomerated particles having a desired agglomerated structure can be obtained. Specifically, it is preferable to first generate primary particles of the silica agglomerated particles in the flame hydrolysis step, and then agglomerate the primary particles of the silica agglomerated particles in the agglomeration step. In the flame hydrolysis step, the primary particle size of the silica agglomerated particles can be controlled by the silica concentration, and in the agglomeration step, the agglomerated structure of the silica agglomerated particles can be controlled by the retention time, which is preferable.

[0063] (Surface treatment agent) The silica aggregate particles of the present invention preferably contain a silica base material that has been treated with hexamethyldisilazane or a polydimethylsiloxane represented by structural formula (A) as a surface treatment agent.

[0064] [ka] (In the formula, R 1 is a carbinol group, a hydroxyl group, an epoxy group, a carboxyl group, an alkyl group, or a hydrogen atom; R 2 is a carbinol group, a hydroxyl group, an epoxy group, a carboxyl group, or a hydrogen atom; m is the average number of repeating units, and m is 30 or more and 200 or less.

[0065] By treating the raw material of the silica agglomerated particles with the above-mentioned surface treatment agent, the surface of the raw material of the silica agglomerated particles can be hydrophobized while leaving silanols on the silica agglomerated particles, which is preferable. In the silica agglomerated particles surface-treated with hexamethyldisilazane, the trimethylsilyl group is a bulky substituent, so that silanols remain under the umbrella of the trimethylsilyl group. Similarly, in the polydimethylsiloxane represented by structural formula (A), the terminal functional group reacts with the silanol of the silica raw material and bonds to the silica raw material, so that silanols remain under the umbrella of the substituent. As a result, the effect of the electrostatic interaction acting between the silanol of the silica agglomerated particles and the BO structure present on the surface of the toner particles is improved, and the transfer void caused by the detachment of the silica agglomerated particles can be suppressed even when used for a long period of time in a low-temperature, low-humidity environment.

[0066] The molecular weight of the polydimethylsiloxane represented by structural formula (A) used in the present invention is, for example, preferably 250 to 50,000, particularly 250 to 10,000, particularly 250 to 5,000, in terms of number average molecular weight. If the molecular weight of the polydimethylsiloxane is too large, it is low in volatility, and it cannot be efficiently evaporated and removed in the surface treatment described below to react with the silica base material. On the other hand, if the molecular weight of the polydimethylsiloxane is too small, it becomes difficult to impart high hydrophobicity.

[0067] The polydimethylsiloxane represented by structural formula (A) is preferably diluted with hexane, toluene, alcohol (aliphatic alcohol having 1 to 8 carbon atoms, such as methanol, ethanol, and propanol), acetone, or in some cases, water, to, for example, about 5 to 50 mass % before use in the surface treatment, which allows for uniform treatment.

[0068] The amount of hexamethyldisilazane and polydimethylsiloxane used for surface treatment of silica agglomerated particles varies depending on the type of silica agglomerated particle raw material (specific surface area, etc.) and the type of surface treatment agent (molecular weight, etc.), but is usually preferably 0.1 to 10 parts by mass, particularly 0.1 to 5 parts by mass, and especially 0.1 to 3 parts by mass, per 100 parts by mass of silica agglomerated particles. If the amount of surface treatment agent used is too small, silica fine particles with high hydrophobicity cannot be obtained. On the other hand, if an excessive amount of surface treatment agent is used, the hydrophobicity of the silica fine particles can be increased, but it is not preferable because it makes the silica fine particles more likely to aggregate.

[0069] (Surface treatment method) The surface treatment method is preferably carried out in an inert gas atmosphere such as a nitrogen atmosphere to prevent hydrolysis and oxidation. Specifically, a method is adopted in which the silica agglomerated particle raw material is placed in a container equipped with a stirring device such as a Henschel mixer, stirred under nitrogen purging, the surface treatment agent is sprayed and mixed with the silica agglomerated particle raw material, and the surface treatment agent is heated to cause a reaction. The spraying may be carried out prior to heating, or may be carried out while heating to the treatment temperature or lower.

[0070] (Processing conditions) The surface treatment is a treatment in which a prescribed amount of the surface treatment agent described above is applied to the raw silica agglomerated particles and heated under stirring, thereby reacting and fixing the surface treatment agent on the surfaces of the raw silica agglomerated particles. Here, the polydimethylsiloxane represented by structural formula (A) may be diluted with the various solvents described above before being applied to the raw silica agglomerated particles.

[0071] The heating temperature in this surface treatment varies depending on the reactivity of the surface treatment agent used, but is preferably 150 to 280°C, and more preferably 200 to 280°C. The treatment time varies depending on the heating temperature and the reactivity of the surface treatment agent used, but is preferably 5 to 120 minutes, and more preferably 5 to 60 minutes, and even more preferably 5 to 40 minutes.

[0072] If the treatment temperature of the surface treatment is too low or the treatment time is too short, the surface treatment agent cannot react sufficiently with the silica base material, and the hydrophobicity of the silica aggregated particles decreases. On the other hand, if the treatment temperature is too high, the hydrophobicity may decrease. Moreover, if the treatment time is too long, the production efficiency decreases, which is not preferable.

[0073] The toner surface may contain inorganic fine particles other than the silica aggregate particles. Examples of the inorganic particles include silica particles, titanium oxide particles, alumina particles, and double oxide particles thereof.

[0074] <Binding resin> The toner particles of the present invention contain a binder resin. The content of the binder resin is preferably 50% by mass or more of the total amount of the resin components in the toner particles.

[0075] The binder resin is not particularly limited, and examples thereof include styrene-acrylic resin, epoxy resin, polyester resin, polyurethane resin, polyamide resin, cellulose resin, polyether resin, mixed resins and composite resins thereof, etc. Among these, styrene-acrylic resin and polyester resin are preferred from the viewpoints of low-temperature fixability and durability stability.

[0076] Examples of the styrene-acrylic resin include homopolymers made of the following polymerizable monomers, copolymers obtained by combining two or more of these, and mixtures thereof.

[0077] Styrenic monomers such as styrene, α-methylstyrene, β-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, p-methoxystyrene and p-phenylstyrene; (Meth)acrylic monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, iso-propyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-amyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, dimethyl phosphate ethyl (meth)acrylate, diethyl phosphate ethyl (meth)acrylate, dibutyl phosphate ethyl (meth)acrylate and 2-benzoyloxyethyl (meth)acrylate, (meth)acrylonitrile, 2-hydroxyethyl (meth)acrylate, (meth)acrylic acid, maleic acid; Vinyl ether monomers such as vinyl methyl ether and vinyl isobutyl ether; vinyl ketone monomers such as vinyl methyl ketone, vinyl ethyl ketone and vinyl isopropenyl ketone; Polyolefins such as ethylene, propylene, and butadiene.

[0078] The styrene acrylic resin may use a polyfunctional polymerizable monomer as required. Examples of the polyfunctional polymerizable monomer include diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 2,2'-bis(4-((meth)acryloxydiethoxy)phenyl)propane, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, divinylbenzene, divinylnaphthalene, and divinyl ether.

[0079] In order to control the degree of polymerization, it is also possible to further add a known chain transfer agent and a polymerization inhibitor. Examples of the polymerization initiator for obtaining the styrene-acrylic resin include organic peroxide-based initiators and azo-based polymerization initiators.

[0080] Examples of the organic peroxide initiator include benzoyl peroxide, lauroyl peroxide, di-α-cumyl peroxide, 2,5-dimethyl-2,5-bis(benzoylperoxy)hexane, bis(4-t-butylcyclohexyl)peroxydicarbonate, 1,1-bis(t-butylperoxy)cyclododecane, t-butylperoxymaleic acid, bis(t-butylperoxy)isophthalate, methyl ethyl ketone peroxide, tert-butylperoxy-2-ethylhexanoate, diisopropyl peroxycarbonate, cumene hydroperoxide, 2,4-dichlorobenzoyl peroxide, and tert-butylperoxypivalate.

[0081] Examples of the azo polymerization initiator include 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, azobismethylbutyronitrile, and 2,2'-azobis-(methyl isobutyrate).

[0082] Furthermore, a redox initiator, which is a combination of an oxidizing substance and a reducing substance, can also be used as the polymerization initiator.

[0083] Oxidizing substances include inorganic peroxides such as hydrogen peroxide, persulfates (sodium, potassium and ammonium salts) and oxidizing metal salts such as tetravalent cerium salts.

[0084] Examples of reducing substances include reducing metal salts (divalent iron salts, monovalent copper salts, and trivalent chromium salts), ammonia, lower amines (amines having from 1 to 6 carbon atoms, such as methylamine and ethylamine), amino compounds such as hydroxylamine, reducing sulfur compounds such as sodium thiosulfate, sodium hydrosulfite, sodium hydrogensulfite, sodium sulfite, and sodium formaldehyde sulfoxylate, lower alcohols (having from 1 to 6 carbon atoms), ascorbic acid or a salt thereof, and lower aldehydes (having from 1 to 6 carbon atoms).

[0085] The polymerization initiator is selected with reference to its 10-hour half-life temperature and is used alone or in combination. The amount of polymerization initiator added varies depending on the desired degree of polymerization, but is generally 0.5 to 20.0 parts by mass per 100.0 parts by mass of polymerizable monomer.

[0086] In the toner of the present invention, a structure in which the binder resin is a styrene acrylic resin and the shell layer is a polyester resin is preferred because it provides a good balance between chargeability and durability and is excellent in suppressing voids during transfer.

[0087] <Polyester resin> The polyester resin used in the toner particles of the present invention will be described below. The polyester resin contained in the shell layer present on the surface of the toner particles of the present invention can also be the polyester resin described below. The polyester resin that can be used in the present invention is not particularly limited, but is preferably an amorphous polyester resin, and examples thereof include the following.

[0088] The polyester resin can be obtained by selecting and combining suitable polycarboxylic acids, polyols, hydroxycarboxylic acids, etc., and synthesizing them using a known method such as an ester exchange method or a polycondensation method. Preferably, the polyester resin contains a condensation polymer of a dicarboxylic acid and a diol.

[0089] Polycarboxylic acids are compounds containing two or more carboxy groups in one molecule. Among them, dicarboxylic acids are compounds containing two carboxy groups in one molecule and are preferably used.

[0090] Examples of the acid include oxalic acid, succinic acid, glutaric acid, maleic acid, adipic acid, β-methyladipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, fumaric acid, citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-carboxylic acid, hexahydroterephthalic acid, malonic acid, pimelic acid, suberic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenylacetic acid, p-phenylenediacetic acid, m-phenylenediacetic acid, o-phenylenediacetic acid, diphenylacetic acid, diphenyl-p,p'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracenedicarboxylic acid, and cyclohexanedicarboxylic acid.

[0091] Examples of polyvalent carboxylic acids other than the dicarboxylic acids include trimellitic acid, trimesic acid, pyromellitic acid, naphthalene tricarboxylic acid, naphthalene tetracarboxylic acid, pyrene tricarboxylic acid, pyrene tetracarboxylic acid, itaconic acid, glutaconic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid, isododecyl succinic acid, isododecenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, etc. These may be used alone or in combination of two or more.

[0092] A polyol is a compound containing two or more hydroxyl groups in one molecule. Among them, a diol is a compound containing two hydroxyl groups in one molecule, and is preferably used.

[0093] Specifically, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,14-eicosanediol. Examples of bisphenols include dimethyl ether glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene ether glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-butenediol, neopentyl glycol, polytetramethylene glycol, hydrogenated bisphenol A, bisphenol A, bisphenol F, bisphenol S, and alkylene oxide (ethylene oxide, propylene oxide, butylene oxide, etc.) adducts of the above bisphenols.

[0094] Among these, preferred are alkylene glycols having from 2 to 12 carbon atoms and alkylene oxide adducts of bisphenols, and particularly preferred are alkylene oxide adducts of bisphenols and their combined use with alkylene glycols having from 2 to 12 carbon atoms. Examples of alkylene oxide adducts of bisphenol A include the compounds represented by the following formula (I).

[0095] [ka] (In formula (I), each R is independently an ethylene or propylene group, each of x and y is an integer of 0 or more, and the average value of x+y is 0 or more and 10 or less.)

[0096] The alkylene oxide adduct of bisphenol A is preferably a propylene oxide adduct and / or an ethylene oxide adduct of bisphenol A. More preferably, it is a propylene oxide adduct. The average value of x+y is preferably 1 or more and 5 or less.

[0097] Examples of trihydric or higher alcohols include glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, tetraethylolbenzoguanamine, sorbitol, trisphenol PA, phenol novolac, cresol novolac, alkylene oxide adducts of the above trihydric or higher polyphenols, etc. These may be used alone or in combination of two or more.

[0098] As for physical properties of the polyester resin used in the present invention, the weight average molecular weight is preferably 9,000 or more and 15,000 or less, and the acid value is preferably 4.0 mgKOH / g or more and 10.0 mgKOH / g or less.

[0099] <Wax> In the toner of the present invention, known waxes can be used.

[0100] Specific examples include petroleum waxes and derivatives thereof, such as paraffin wax, microcrystalline wax, and petrolatum, montan wax and derivatives thereof, hydrocarbon waxes produced by the Fischer-Tropsch process and derivatives thereof, polyolefin waxes and derivatives thereof, such as polyethylene, natural waxes and derivatives thereof, such as carnauba wax and candelilla wax, and derivatives thereof. Derivatives also include oxides, block copolymers with vinyl monomers, and graft modified products.

[0101] Other examples include alcohols such as higher aliphatic alcohols, fatty acids such as stearic acid and palmitic acid or their acid amides, esters and ketones, hydrogenated castor oil and its derivatives, vegetable waxes and animal waxes. These can be used alone or in combination.

[0102] Among these, polyolefin, Fischer-Tropsch hydrocarbon wax, or petroleum wax is preferably used since it tends to improve the developability and transferability. An antioxidant may be added to these waxes within a range that does not affect the effects of the toner. In addition, from the viewpoint of phase separation with respect to the binder resin or crystallization temperature, higher fatty acid esters such as behenyl behenate and dibehenyl sebacate are suitable examples.

[0103] The content of the release agent is preferably 1.0 part by mass or more and 30.0 parts by mass or less with respect to 100.0 parts by mass of the binder resin.

[0104] The melting point of the release agent is preferably from 30° C. to 120° C., and more preferably from 60° C. to 100° C. By using a release agent having the above-mentioned thermal characteristics, the release effect is efficiently exerted and a wider fixing area is secured.

[0105] <Plasticizer> The toner particles may contain a crystalline plasticizer in order to improve the sharp melting property. The plasticizer is not particularly limited, and any of the known plasticizers used in toners such as those described below can be used.

[0106] Specifically, the esters include esters of monohydric alcohols and aliphatic carboxylic acids, such as behenyl behenate, stearyl stearate, and palmityl palmitate, or esters of monohydric carboxylic acids and aliphatic alcohols; esters of dihydric alcohols and aliphatic carboxylic acids, such as ethylene glycol distearate, dibehenyl sebacate, and hexanediol dibehenate, or esters of dihydric carboxylic acids and aliphatic alcohols; esters of trihydric alcohols and aliphatic carboxylic acids, such as glycerin tribehenate, or esters of trihydric carboxylic acids and aliphatic alcohols; and pentaerythritol tetrastearate. esters of tetrahydric alcohols and aliphatic carboxylic acids, such as stearate and pentaerythritol tetrapalmitate, or esters of tetrahydric carboxylic acids and aliphatic alcohols; esters of hexahydric alcohols and aliphatic carboxylic acids, such as dipentaerythritol hexastearate and dipentaerythritol hexapalmitate, or esters of hexahydric carboxylic acids and aliphatic alcohols; esters of polyhydric alcohols and aliphatic carboxylic acids, such as polyglycerin behenate, or esters of polyhydric carboxylic acids and aliphatic alcohols; natural ester waxes, such as carnauba wax and rice wax. These may be used alone or in combination.

[0107] <Coloring agent> The toner particles may contain a colorant. Known pigments and dyes can be used as the colorant. Pigments are preferred as the colorant because they have excellent weather resistance.

[0108] Cyan colorants include copper phthalocyanine compounds and their derivatives, anthraquinone compounds, and basic dye lake compounds. Specific examples include the following: CI Pigment Blue 1, 7, 15, 15:1, 15:2, 15:3, 15:4, 60, 62, and 66.

[0109] Magenta colorants include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. Specific examples include CI Pigment Red 2, 3, 5, 6, 7, 23, 48:2, 48:3, 48:4, 57:1, 81:1, 122, 144, 146, 150, 166, 169, 177, 184, 185, 202, 206, 220, 221, and 254, and CI Pigment Violet 19.

[0110] Yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds. Specific examples include the following: CI Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 185, 191, and 194.

[0111] Examples of black colorants include those toned to black using the above yellow, magenta and cyan colorants, as well as carbon black and magnetic materials.

[0112] These colorants can be used alone or in mixture, or in the form of a solid solution. The colorant is preferably used in an amount of 1.0 to 20.0 parts by mass per 100.0 parts by mass of the binder resin. When using a magnetic material in a water-based medium, as described below, a hydrophobic treatment can be carried out in order to stably contain the magnetic material in the resin.

[0113] <Charge control agents and charge control resins> The toner particles may contain a charge control agent or a charge control resin. Any known charge control agent can be used as the charge control agent, and a charge control agent that has a high triboelectric charging speed and can stably maintain a constant triboelectric charge amount is particularly preferred. Furthermore, when the toner particles are produced by a suspension polymerization method, a charge control agent that has low polymerization inhibition and is substantially free of solubilized matter in an aqueous medium is particularly preferred.

[0114] Examples of toners that control the toner to be negatively charged include monoazo metal compounds, acetylacetone metal compounds, aromatic oxycarboxylic acids, aromatic dicarboxylic acids, oxycarboxylic and dicarboxylic acid-based metal compounds, aromatic oxycarboxylic acids, aromatic mono- and polycarboxylic acids and their metal salts, anhydrides, esters, phenol derivatives such as bisphenol, urea derivatives, metal-containing salicylic acid-based compounds, metal-containing naphthoic acid-based compounds, boron compounds, quaternary ammonium salts, calixarenes, and charge control resins.

[0115] The charge control resin may be a polymer or copolymer having a sulfonic acid group, a sulfonate group, or a sulfonate ester group. As the polymer having a sulfonic acid group, a sulfonate group, or a sulfonate ester group, a polymer containing a sulfonic acid group-containing acrylamide monomer or a sulfonate group-containing methacrylamide monomer in a copolymerization ratio of 2% by mass or more is preferable, and a polymer containing a sulfonic acid group-containing methacrylamide monomer in a copolymerization ratio of 5% by mass or more is more preferable.

[0116] The charge control resin preferably has a glass transition temperature (Tg) of 35° C. or more and 90° C. or less, a peak molecular weight (Mp) of 10,000 or more and 30,000 or less, and a weight average molecular weight (Mw) of 25,000 or more and 50,000 or less. When used, it is possible to impart preferable triboelectric charging characteristics without affecting the thermal characteristics required for the toner particles. Furthermore, when the charge control resin contains a sulfonic acid group, for example, the dispersibility of the charge control resin itself in the polymerizable monomer composition and the dispersibility of the colorant are improved, and the coloring power, transparency, and triboelectric charging characteristics can be further improved.

[0117] These charge control agents or charge control resins may be added alone or in combination of two or more. The amount of the charge control agent or charge control resin added is preferably 0.01 parts by mass or more and 20.0 parts by mass or less, more preferably 0.5 parts by mass or more and 10.0 parts by mass or less, relative to 100.0 parts by mass of the binder resin.

[0118] [Method of producing toner particles] The method for producing the toner is not particularly limited, and known methods such as a pulverization method, a suspension polymerization method, a solution suspension method, an emulsion aggregation method, and a dispersion polymerization method can be used. In any of these methods for producing toner particles, it is preferable to obtain toner particles by adding a boric acid source when mixing raw materials. Here, the toner is preferably produced by the method shown below. That is, the toner is preferably produced by an emulsion aggregation method.

[0119] Preferably, the method for producing the toner comprises the following steps (1) to (3): (1) a dispersing step for preparing a dispersion liquid of binder resin fine particles containing a binder resin; (2) The binder resin particles contained in the dispersion of the binder resin particles are aggregated to form aggregates. an agglomeration step, and (3) a fusion step of heating the aggregates to fuse them together having In step (2) or (3), a boric acid source is added to the dispersion.

[0120] Hereinafter, a detailed description will be given of a method for producing toner particles by an emulsion aggregation method.

[0121] (Dispersion liquid preparation process) The binder resin particle dispersion liquid is prepared, for example, as follows: When the binder resin is a homopolymer or copolymer (vinyl resin) of a vinyl monomer, the vinyl monomer is subjected to emulsion polymerization or seed polymerization in an ionic surfactant to prepare a dispersion liquid in which the vinyl resin particles are dispersed in the ionic surfactant.

[0122] When the binder resin is a resin other than a vinyl resin such as a polyester resin, the resin is mixed with an aqueous medium in which an ionic surfactant or a polymer electrolyte is dissolved.

[0123] Thereafter, this solution is heated to a temperature equal to or higher than the melting point or softening point of the resin to dissolve it, and a dispersion liquid in which the binder resin particles are dispersed in the ionic surfactant is prepared using a dispersing machine with strong shear force such as a homogenizer.

[0124] The dispersion means is not particularly limited, and examples thereof include known dispersion devices such as a rotary shear homogenizer, a ball mill having a media, a sand mill, and a dyno mill. A phase inversion emulsification method may also be used as a method for preparing a dispersion. The phase inversion emulsification method is a method in which a binder resin is dissolved in an organic solvent, a neutralizer and a dispersion stabilizer are added as necessary, and an aqueous solvent is dropped under stirring to obtain emulsified particles, and then the organic solvent in the resin dispersion is removed to obtain an emulsion. In this case, the order of adding the neutralizer and the dispersion stabilizer may be changed.

[0125] In the emulsion aggregation method, a colorant particle dispersion liquid may be used as necessary. The colorant particle dispersion liquid is obtained by dispersing at least colorant particles in a dispersant.

[0126] In the emulsion aggregation method, a plasticizer particle dispersion may be used as necessary. The plasticizer particle dispersion is prepared by dispersing at least plasticizer particles in a dispersant.

[0127] (Agglutination process) The aggregation step of forming aggregated particles is a step of forming aggregated particles containing binder resin particles, wax particles, and, if necessary, colorant particles and plasticizer particles in an aqueous medium containing binder resin particles, wax particles, and, if necessary, colorant particles and plasticizer particles.

[0128] (fusion process) The fusion process is a process in which the obtained aggregated particles are heated and fused. Prior to the fusion process, a pH adjuster, a polar surfactant, a non-polar surfactant, etc. may be appropriately added to prevent fusion between toner particles.

[0129] The heating temperature may be from the glass transition temperature of the resin contained in the aggregated particles (when there are two or more types of resin, the glass transition temperature of the resin having the highest glass transition temperature) to the decomposition temperature of the resin. Therefore, the heating temperature differs depending on the type of resin of the binder resin particles and cannot be generally specified, but is generally from the glass transition temperature of the resin contained in the aggregated particles to 140° C. or less. The heating can be performed using a heating device or tool known per se.

[0130] The fusion time is short if the heating temperature is high, and long if the heating temperature is low. In other words, the fusion time depends on the heating temperature and cannot be specified in general, but it is generally between 30 minutes and 10 hours.

[0131] The toner particles are obtained by carrying out the above-mentioned dispersion liquid preparation step, aggregation step, and fusion step. The obtained toner particles can be directly filtered, washed, and dried by a known method to obtain the toner particles.

[0132] In the method for producing toner particles, it is preferable to have a shell forming step in which, after obtaining toner particles (core particles) by any of the above-mentioned production methods, resin fine particles containing a shell resin are further added to the aqueous medium in which the core particles are dispersed, and are attached to the core particles to form a shell. In the method for producing toner by emulsion aggregation, it is preferable to have a shell forming step in which, after forming aggregated particles (core particles) by the aggregation step, resin fine particles containing a shell resin are further added to adhere to the core particles to form a shell. That is, it is preferable that the toner particles have core particles containing a binder resin and a shell on the surface of the core particles. The resin for the shell may be the same as the binder resin, or a different resin may be used. The amount of the resin for the shell added is preferably 1 part by mass or more and 10 parts by mass or less, more preferably 2 parts by mass or more and 7 parts by mass or less, relative to 100 parts by mass of the binder resin contained in the core particles.

[0133] In this case, the method for producing the toner preferably includes the following steps. (1) a dispersing step for preparing a dispersion liquid of binder resin fine particles containing a binder resin; (2-1) Forming aggregates by aggregating the binder resin fine particles contained in the dispersion of the binder resin fine particles a flocculation step for (2-2) Adding resin particles containing a shell resin to the dispersion liquid containing the aggregates to form the aggregates a shell forming step of attaching the agglomerate to the shell to form an agglomerate having a shell; and (3) a fusion step of heating the agglomerates on which the shells have been formed to fuse them together; In order to make it easier to incorporate boric acid in the vicinity of the surface of the toner particles, it is preferable to add a boric acid source together with the resin particles containing the shell resin to the dispersion liquid containing the aggregates in the step (2-2).

[0134] The boric acid source may be boric acid or a compound that can be converted to boric acid by pH control during toner production. For example, at least one selected from the group consisting of boric acid, borax, organic boric acid, borate salts, borate esters, etc. may be used. For example, a boric acid source may be added and controlled so that boric acid is contained in the aggregates. Preferably, the pH is controlled to an acidic condition in the aggregation step (2-1), and then the shell formation step is performed.

[0135] The boric acid may be present in the aggregate in an unsubstituted state. The boric acid source is preferably at least one selected from the group consisting of boric acid and borax. When the toner is produced in an aqueous medium, it is preferable to add the boric acid source as a borate salt from the viewpoint of reactivity and production stability. Specifically, the boric acid source more preferably includes at least one selected from the group consisting of sodium tetraborate, borax, ammonium borate, etc., and further preferably is borax.

[0136] Borax is represented by the decahydrate of sodium tetraborate (Na2B4O7), and since it changes to boric acid in an acidic aqueous solution, borax is preferably used when used in an aqueous medium under an acidic environment. The addition method may be in the form of either a dry powder or an aqueous solution dissolved in an aqueous medium, but in order to cause uniform aggregation, it is preferable to add it in the form of an aqueous solution. The concentration of the aqueous solution may be appropriately changed depending on the concentration contained in the toner, and is, for example, 1 to 20 mass %. In order to change to boric acid, it is preferable to make the pH an acidic condition before, during, or after the addition. For example, it may be controlled to 1.5 to 5.0, preferably 2.0 to 4.0. The pH is preferably controlled before the aggregation step in which aggregates are formed.

[0137] That is, it is preferable to control the pH to an acidic condition in a mixing step, prior to the aggregation step, in which the binder resin fine particle dispersion and, if necessary, other dispersions such as the release agent fine particle dispersion are mixed.

[0138] <Various measurement methods> Various measuring methods relating to the physical properties of the present invention will be described below.

[0139] <Measuring method for fragment peaks derived from boron atoms and BO structures> The detection of fragment peaks originating from boron atoms and BO structures in the toner was carried out by using TOF-SIMS.

[0140] To measure the fragment ions on the toner surface using TOF-SIMS, TRIFT-IV manufactured by ULVAC-PHI, Inc. The analysis conditions are as follows: Sample preparation: Attaching silica particles to an indium sheet Primary ion: Au ion Acceleration voltage: 30 kV Charge neutralization mode: On Measurement mode: Positive Raster: 200μm Measurement time: 60s From the obtained mass profile of secondary ion mass / secondary ion charge number (m / z), it is confirmed whether or not fragment ions derived from boron atoms are observed. In the present invention, the presence or absence of a BO bond is judged based on the presence or absence of a mass profile of BO2, taking into account the balance of peak intensity.

[0141] <Method of measuring number-based primary particle size, maximum Feret diameter, and aspect ratio of silica agglomerated particles> The number-based primary particle size, maximum Feret's diameter, and aspect ratio of the silica aggregate particles are calculated from an image of silica fine particles on the toner surface taken with a Hitachi ultra-high resolution field emission scanning electron microscope S-4800 (Hitachi High-Technologies Corporation). The image taking conditions for the S-4800 are as follows.

[0142] (1) Sample preparation Apply a thin layer of conductive paste to a sample stage (aluminum sample stage 15 mm x 6 mm) and spray toner onto it. Then use air to remove excess toner from the sample stage and dry thoroughly. Set the sample stage in the sample holder and adjust the sample stage height to 36 mm using the sample height gauge.

[0143] (2) S-4800 observation condition setting The number-based primary particle size, maximum Feret's diameter, and aspect ratio of silica agglomerated particles are calculated using images obtained by backscattered electron image observation with the S-4800. Backscattered electron images cause less charge-up of silica particles than secondary electron images, so the particle size of silica particles can be measured with high accuracy.

[0144] Pour liquid nitrogen into the anti-contamination trap attached to the S-4800 housing until it overflows, and leave it for 30 minutes. Start the S-4800's "PC-SEM" and perform flushing (cleaning the FE chip, which is the electron source). Click the accelerating voltage display area on the control panel on the screen, and press the [Flushing] button to open the flushing execution dialog. Check that the flushing intensity is 2, and execute it. Check that the emission current due to flushing is 20 to 40 μA. Insert the sample holder into the sample chamber of the S-4800 housing. Press [Origin] on the control panel to move the sample holder to the observation position.

[0145] Click the accelerating voltage display to open the HV setting dialog, and set the accelerating voltage to [0.8kV] and the emission current to [20μA]. In the [Basic] tab of the operation panel, set the signal selection to [SE], select the SE detector to [Upper (U)] and [+BSE], and select [LA100] in the selection box to the right of [+BSE] to set the mode to observation with backscattered electron images. In the same [Basic] tab of the operation panel, set the probe current in the electron optical system condition block to [Normal], the focus mode to [UHR], and the WD to [3.0mm]. Press the [ON] button in the accelerating voltage display of the control panel to apply the accelerating voltage.

[0146] (3) Focus adjustment Drag within the magnification display area on the control panel to set the magnification to 100,000 (100k). Rotate the focus knob [COARSE] on the operation panel to adjust the aperture alignment once the image is in focus to a certain extent. Click [Align] on the control panel to display the alignment dialog and select [Beam]. Rotate the STIGMA / ALIGNMENT knobs (X, Y) on the operation panel to move the displayed beam to the center of the concentric circles. Next, select [Aperture] and rotate the STIGMA / ALIGNMENT knobs (X, Y) one by one to stop the image movement or adjust it so that it moves as little as possible. Close the aperture dialog and use autofocus to adjust the focus. Repeat this operation two more times to adjust the focus.

[0147] (4) Image storage Adjust the brightness in ABC mode, take a photo with a size of 640 x 480 pixels, and save it. Use this image file to perform the following analysis. Take one photo for each silica aggregate particle, and obtain images for at least 300 toner particles.

[0148] (5) Calculation of primary particle size based on number of silica agglomerated particles The primary particle size of 300 silica agglomerated particles is measured to determine the number-based primary particle size. Since the silica agglomerated particles exist as aggregates, the maximum diameter of those that can be confirmed as primary particles is determined, and the number-based primary particle size of the silica agglomerated particles is determined by arithmetically averaging the maximum diameters obtained.

[0149] (6) Calculation of maximum Feret diameter and aspect ratio of silica aggregate particles The maximum Feret's diameter and aspect ratio of the silica agglomerated particles are calculated by analyzing the 300 silica agglomerated particle images taken in the above (4) Image storage using image analysis software Image-Pro Plus ver.5.0 (Nippon Roper Co., Ltd.). The analysis conditions for the image analysis software Image-Pro Plus ver.5.0 are as follows. Software Image-ProPlus5.1J

[0150] From the "Measurement" menu on the toolbar, select "Count / Size" and then "Options" to set the binarization conditions. In the object extraction options, select 8 connectivity and set smoothing to 0. In addition, do not select pre-sort, fill holes, or encompass lines, and set "Exclude borders" to "None." From the "Measurement" menu on the toolbar, select "Shape descriptors" and "Feret's diameter."

[0151] The maximum Feret diameter and aspect ratio of the silica agglomerated particles are calculated by automatically binarizing the data using "Processing"-Binarization to determine the maximum Feret diameter and aspect ratio of the silica agglomerated particles.

[0152] <Measurement of the amount of silanol defined by formula (1) of silica agglomerated particles> The silanol amount of the silica agglomerated particles defined by the formula (1) is determined by using silica agglomerated particles separated from the toner by the method for separating silica agglomerated particles from the toner surface described below.

[0153] (1) Method for separating silica aggregate particles from the toner surface Add 1.6 kg of sucrose (Kishida Chemical) to 1 L of ion-exchanged water and dissolve it in a hot water bath to prepare a concentrated sucrose solution. Place 31 g of the concentrated sucrose solution and 6 mL of Contaminon N (a 10% by weight aqueous solution of a neutral detergent for cleaning precision measuring instruments, pH 7, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) in a centrifuge tube to prepare a dispersion. Add 10 g of toner to this dispersion, and break up the toner clumps with a spatula or the like.

[0154] The centrifuge tube is placed in an Iwaki Sangyo KM Shaker (model: V.SX) and shaken for 20 minutes at 350 reciprocations per minute. After shaking, the solution is transferred to a glass tube (50 mL) for a swing rotor and centrifuged at 3,500 rpm for 30 minutes.

[0155] After centrifugation, the toner particles are present in the top layer in the glass tube, and the inorganic fine particle mixture containing silica aggregate particles is present in the aqueous solution side of the lower layer. The aqueous solution of the lower layer is separated and then dried to obtain the inorganic fine particle mixture. The above centrifugation process is repeated until the amount of the obtained inorganic fine particle mixture is 10 g or more in total.

[0156] Next, 10 g of the obtained inorganic fine particle mixture is dispersed in a dispersion liquid containing 100 mL of ion-exchanged water and 6 mL of Contaminon N. The obtained dispersion liquid is transferred to a glass tube (50 mL) for a swing rotor, and centrifuged in a centrifuge at 3500 rpm for 30 minutes.

[0157] After centrifugation, the silica aggregate particles are present in the top layer in the glass tube, and other inorganic fine particles are present in the aqueous solution in the lower layer. The aqueous solution in the upper layer is collected and centrifuged repeatedly as necessary. After sufficient separation, the dispersion is dried and the silica aggregate particles are collected.

[0158] Next, the amount of silanol in the silica aggregate particles recovered from the toner is measured under the measurement conditions shown below.

[0159] Mix 25.0 g of ethanol and 75.0 g of 20% by mass sodium chloride aqueous solution to prepare sample solution 1. Also, weigh out 2.00 g of silica microparticles into a glass bottle and add a mixed solvent of 25.0 g of ethanol and 75.0 g of 20% by mass sodium chloride aqueous solution to prepare sample solution 2. Stir sample solution 2 with a magnetic stirrer for 5 minutes or more to disperse the silica microparticles.

[0160] Next, for each of sample solutions 1 and 2, measure the pH change of the sample solution while dropping 0.1 mol / L sodium hydroxide solution at 0.01 mL / min. Record the titer (L) of the sodium hydroxide solution when the pH reaches 9.0. 2 Amount of silanol per nanometer S (pieces / nm 2 ) can be calculated. S = {(ab) × c × NA} / (d × e) a: NaOH titration amount (L) of sample solution 2 b: NaOH titration amount (L) of sample solution 1 c: Concentration of the NaOH solution used in the titration (mol / L) NA: Avogadro's number d: mass of silica agglomerated particles (g) e: BET specific surface area of ​​silica agglomerated particles (nm 2 / g)

[0161] <Measurement of the amount of boron atoms present on the surface of toner particles> The content of boron atoms on the surface of the toner particles is measured by the following measurement method using an inductively coupled plasma mass spectrometer (ICP-MS (manufactured by Agilent Technologies)). (a) 20 g of a 50% by weight aqueous solution of methanol is added to 1 g of the toner, and the mixture is shaken for 5 minutes at a shaking speed of 150 revolutions per minute using a shaker, and then the toner is taken out. This operation is repeated 10 times. (b) Prepare a 6.0 mol / L aqueous solution of nitric acid using 60% nitric acid (Kanto Chemical, Ultrapur) and ultrapure water. Add 5.00 g of 6.0 mol / L nitric acid to 50.0 mg of the toner, mix, and stir to prepare a toner-containing solution sample. Leave the sample for 120 minutes to extract boron atoms from the surface of the toner particles. (c) After filtering using filter paper with a pore size of 1 μm to prepare a toner cake, 10.00 g of ultrapure water is added to the toner cake as washing water to separate the toner from the toner-containing solution sample. Ultrapure water is added to the filtrate solution sample so that the total weight becomes 50.00 g to prepare a solution sample for boron atom measurement. (d) Using an inductively coupled plasma mass spectrometer (ICP-MS), a blank solution sample was prepared by adding ultrapure water to 5.00 g of 6.0 mol / L aqueous nitric acid solution to a total of 50.00 g, and a solution sample with a known boron atom content was prepared, and a calibration curve was created. The boron atom content of the toner surface was measured by quantifying the boron atoms contained in the boron atom measurement sample.

[0162] <Method for measuring the coverage rate of silica aggregate particles on the toner particle surface> The coverage rate of silica agglomerated particles is calculated by analyzing a toner surface image taken with a Hitachi ultra-high resolution field emission scanning electron microscope S-4800 (Hitachi High-Technologies Corporation) using image analysis software Image-Pro Plus ver.5.0 (Nippon Roper Co., Ltd.). The image taking conditions for the S-4800 are as follows. Note that (1) sample preparation and (2) S-4800 observation condition setting are performed in the same manner as the measurement methods for the number-based primary particle size, maximum Feret's diameter, and aspect ratio of the silica agglomerated particles described above.

[0163] (3) Focus adjustment Rotate the focus knob [COARSE] on the operation panel, and adjust the aperture alignment once the image is in focus to a certain extent. Click [Align] on the control panel to display the alignment dialog, and select [Beam]. Rotate the STIGMA / ALIGNMENT knobs (X, Y) on the operation panel to move the displayed beam to the center of the concentric circles. Next, select [Aperture], and rotate the STIGMA / ALIGNMENT knobs (X, Y) one by one to stop the image movement or to minimize its movement. Close the aperture dialog, and adjust the focus using autofocus. After that, set the magnification to 50,000 (50k), and adjust the focus using the focus knob and STIGMA / ALIGNMENT knob in the same way as above, and then adjust the focus using autofocus again. Repeat this operation two more times to adjust the focus. Here, if the inclination angle of the observation surface is large, the measurement accuracy of the coverage rate is likely to be low, so when adjusting the focus, select an observation surface with as little surface inclination as possible for analysis by selecting one that can simultaneously bring the entire observation surface into focus.

[0164] (4) Image storage Adjust the brightness in ABC mode, take a photo with a size of 640 x 480 pixels, and save it. Use this image file to perform the following analysis. Take one photo for each toner, and obtain images of at least 25 toner particles.

[0165] (5) Image analysis In the present invention, the image obtained by the above-mentioned method is binarized using the following analysis software to calculate the coverage. At this time, the above-mentioned screen is divided into 12 squares and each is analyzed. The analysis conditions for the image analysis software Image-Pro Plus ver.5.0 are as follows. Software Image-ProPlus5.1J

[0166] From the "Measure" menu on the toolbar, select "Count / Size" and then "Options" to set the binarization conditions. In the object extraction options, select 8 connectivity and set smoothing to 0. In addition, do not select pre-select, fill holes, or inclusion lines, and set "Exclude borders" to "None." From the "Measure" menu on the toolbar, select "Measurement item" and enter 2 to 107 as the area selection range.

[0167] The coverage rate X is calculated by enclosing a square region. In this case, the area (C) of the region should be 24,000 to 26,000 pixels. Automatic binarization is performed using "Processing"-Binarization, and the total area (D) of the region without inorganic fine particles (A) (e.g. silica) is calculated.

[0168] The coverage rate can be calculated from the area C of the square region and the total area D of the region without inorganic fine particles (A) by the following formula. Coverage rate (%)=100-(D / C×100)

[0169] The average value of all the data obtained is taken as the coverage rate.

[0170] <Dispersion evaluation index of silica aggregate particles on the toner particle surface> The dispersion evaluation index of silica aggregate particles on the toner particle surface is calculated using a scanning electron microscope "S-4800". The toner with silica aggregate particles added externally was observed in a 10,000 times magnified field of view at an accelerating voltage of 1.0 kV in the same field of view. The following calculations were made from the observed images using the image processing software "ImageJ".

[0171] The images were binarized so that only silica agglomerated particles were extracted, and the number of external additives n and the coordinates of the center of gravity for all external additives were calculated, and the distance dn min between each silica agglomerated particle and the nearest silica agglomerated particle was calculated. If the average value of the nearest distance between external additives in the image is dave, the degree of dispersion is expressed by the following formula.

[0172]

number

[0173] The degree of dispersion of 50 toner particles randomly observed was determined by the above procedure, and the average value was taken as the degree of dispersion evaluation index.

[0174] <Method for measuring maximum Feret diameter and aspect ratio of titanium oxide particles> The maximum Feret diameter and aspect ratio of the titanium oxide particles are measured in the same manner as in the measurement of the number-based primary particle diameter, maximum Feret diameter, and aspect ratio of the silica agglomerated particles.

[0175] Furthermore, by combining elemental analysis using energy dispersive X-ray analysis (EDS), it is possible to determine whether or not the toner is titanium oxide. Specifically, a scanning electron microscope "S-4800" (product name; manufactured by Hitachi) is used to observe the toner at a field of view magnified up to 100,000 times. The focus is adjusted to the surface of the toner particles, and the external additive to be identified is observed. An EDS analysis is performed on the external additive to be identified, and it is possible to determine whether it is titanium oxide from the elemental peak.

[0176] <Method for measuring average circularity of toner> The average circularity of the toner particles was measured using a flow type particle image analyzer "FPIA-3000" (manufactured by Sysmex Corporation) under the measurement and analysis conditions during the calibration work.

[0177] The specific measurement method is as follows. First, about 20 ml of ion-exchanged water from which impurities such as solids have been removed is placed in a glass container. About 0.2 ml of a dilution of "Contaminon N" (a 10% aqueous solution of a neutral detergent for cleaning precision measuring instruments with a pH of 7, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) diluted about three times by mass with ion-exchanged water is added to the container. About 0.02 g of the measurement sample is further added, and the dispersion treatment is performed for 2 minutes using an ultrasonic disperser to obtain a dispersion liquid for measurement. At that time, the dispersion liquid is appropriately cooled so that the temperature is 10°C or higher and 40°C or lower. As the ultrasonic disperser, a tabletop ultrasonic cleaner disperser (e.g., "VS-150" (manufactured by Vervoclear Co., Ltd.) with an oscillation frequency of 50 kHz and an electrical output of 150 W is used, a predetermined amount of ion-exchanged water is placed in the water tank, and about 2 ml of the Contaminon N is added to the water tank.

[0178] For the measurement, the flow type particle image analyzer equipped with "LUCPLFLN" (magnification 20 times, numerical aperture 0.40) was used as the objective lens, and particle sheath "PSE-900A" (manufactured by Sysmex Corporation) was used as the sheath liquid. The dispersion liquid prepared according to the above procedure was introduced into the flow type particle image analyzer, and 2000 toner particles were measured in HPF measurement mode and total count mode. Then, the binarization threshold during particle analysis was set to 85%, and the analyzed particle diameter was limited to a circle equivalent diameter of 1.977 μm or more and less than 39.54 μm, and the average circularity of the toner particles was obtained. For the measurement, automatic focus adjustment was performed using standard latex particles (for example, "RESEARCH AND TEST PARTICLES Latex Microsphere Suspensions 5100A" manufactured by Duke Scientific Co., Ltd., diluted with ion-exchanged water) before the start of the measurement. Thereafter, it is preferable to perform focus adjustment every 2 hours from the start of the measurement.

[0179] In the examples of the present application, a flow-type particle image analyzer was used that had been calibrated by Sysmex Corp. and had a calibration certificate issued by Sysmex Corp. Measurements were performed under the same measurement and analysis conditions as when the calibration certificate was received, except that the particle diameters analyzed were limited to a circle-equivalent diameter of 1.977 μm or more and less than 39.54 μm.

[0180] <Method for measuring thickness T of shell layer present on toner particle surface> The shell layer is a region that does not contain crystalline material and is 25% or less of the distance from the contour of the toner cross section to the center of gravity of the cross section. The cross sections of 100 or more toner particles were observed, and the average value of the distance from the contour to the region that does not contain crystalline material was calculated, and this value was taken as the thickness of the shell layer.

[0181] <Determining the presence of dodecylbenzenesulfonic acid or dodecylbenzenesulfonate salts in toner> The presence or absence of dodecylbenzenesulfonic acid or dodecylbenzenesulfonate salts is determined by analysis using the MS / MS (mass-mass spectrometry) method with a tandem mass spectrometer directly connected to a liquid chromatograph ESI / MS analyzer.

[0182] The MS / MS method is a mass spectrometry technique that allows the detection of fragments with smaller molecular weights by measuring fragments extracted in a first analytical system using a second analytical system, making it easy to perform structural analysis of a sample. Dissolution condition A: At 25° C., 10 times the mass of the toner is used in methanol (JIS K8891 equivalent), and the toner is stirred for 10 hours at a rotor speed of 200 rpm using a stirring device. Centrifugation condition A: Rotation is performed for 30 minutes at 25° C., a rotation radius of 10.1 cm, and a rotation speed of 3,500 rpm.

[0183] The sample is prepared by using a toner under the above-mentioned elution condition A, and then separated into a solid content and a supernatant liquid under the above-mentioned centrifugation condition A.

[0184] The supernatant obtained by the above adjustment is supplied to the measuring device described below, and liquid chromatograph ESI / MS analysis is performed under the analytical condition B described below. A mass spectrometry spectrum of the anions is obtained, and it is confirmed that a peak is detected at m / z=325. In addition, the ion detected as a peak at m / z=325 is supplied as a precursor ion to a tandem mass spectrometer, and an MS / MS spectrum is obtained under the analytical condition B. Measurement device: Ultimate3000 (Thermo Fisher Scientific) Mass spectrometer: LCQ Fleet (manufactured by Thermo Fisher Scientific) Analysis condition B: Under the following conditions, the ionized material is detected as anion under the capillary voltage: -35 V, tube lens voltage: -110 V, and the ion detected at m / z = 325 is selected as a precursor ion, and the ion that is collision-induced dissociated in an inert gas: He with a collision energy of 35 eV is detected. Ionization method: Electrospray Ionization (ESI) Sheath Gas: 10 (arb.unit.) Aux Gas: 5 (arb. unit.) Spray voltage: 5kV Capillary temperature: 275℃ Mobile phase: Methanol (JISK8891 standard equivalent) Column: Not used (no stationary phase) Flow rate: 1ml / min Injection volume: 10μl Chromatogram detector: UV detector MS acquisition time: 5min MS measurement range: 50-1500 m / z Collision inert gas: He (helium) Collision energy: 35 eV

[0185] <Method for measuring molecular weight of polyester resin> The molecular weight of the polyester resin is measured by gel permeation chromatography (GPC) as follows.

[0186] First, polyester resin is dissolved in tetrahydrofuran (THF) at room temperature. The obtained solution is then filtered through a solvent-resistant membrane filter "Maeshori Disk" (manufactured by Tosoh Corporation) with a pore size of 0.2 μm to obtain a sample solution. The sample solution is adjusted so that the concentration of components soluble in THF is 0.8 mass%. This sample solution is used to perform measurements under the following conditions. Equipment: High-speed GPC equipment "HLC-8220GPC" [Tosoh Corporation] Column: LF-604 in two columns Eluent:THF Flow rate: 0.6ml / min Oven temperature: 40℃ Sample injection volume: 0.020 ml In calculating the molecular weight of the sample, a molecular weight calibration curve prepared using standard polystyrene resins (e.g., trade names "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) is used.

[0187] <Acid value of polyester resin> The acid value is the number of milligrams of potassium hydroxide required to neutralize the acid contained in 1 g of a sample. The acid value in the present invention is measured in accordance with JIS K 0070-1992, and specifically, is measured according to the following procedure.

[0188] Titration is performed using a 0.1 mol / l potassium hydroxide ethyl alcohol solution (Kishida Chemical Co., Ltd.). The factor of the potassium hydroxide ethyl alcohol solution can be determined using a potentiometric titrator (Kyoto Electronics Manufacturing Co., Ltd. Potentiometric titration measuring device AT-510). 100 ml of 0.100 mol / l hydrochloric acid is placed in a 250 ml tall beaker and titrated with the potassium hydroxide ethyl alcohol solution, and the factor is determined from the amount of the potassium hydroxide ethyl alcohol solution required for neutralization. The 0.100 mol / l hydrochloric acid used is prepared in accordance with JIS K 8001-1998.

[0189] The conditions for measuring the acid value are shown below. Titrator: Potentiometric titrator AT-510 (Kyoto Electronics Manufacturing Co., Ltd.) Electrode: Composite glass electrode double junction type (Kyoto Electronics Manufacturing Co., Ltd.) Control software for titrator: AT-WIN Titration analysis software: Tview The titration parameters and control parameters during titration are as follows: Titration parameters Titration mode: Blank titration Titration method: Total volume titration Maximum titration volume: 20ml Waiting time before titration: 30 seconds Titration direction: automatic Control Parameter End point potential: 30dE End point potential: 50 dE / dmL End point detection judgment: Not set Control speed mode: Standard Gain: 1 Data collection potential: 4mV Data collection titration amount: 0.1ml Main test: 0.100 g of the measurement sample is accurately weighed into a 250 ml tall beaker, 150 ml of a mixed solution of toluene / ethanol (3:1) is added, and the mixture is dissolved over 1 hour. Using the above potentiometric titration apparatus, titrate with the above potassium hydroxide ethyl alcohol solution. Blank test: Perform titration in the same manner as above, except that no sample is used (i.e., only a mixed solution of toluene / ethanol (3:1) is used). Substitute the obtained results into the following formula to calculate the acid value. A = [(CB) × f × 5.611] / S (In the formula, A is the acid value (mgKOH / g), B is the amount (ml) of potassium hydroxide ethyl alcohol solution added for the blank test, C is the amount (ml) of potassium hydroxide ethyl alcohol solution added for the main test, f is the factor of the potassium hydroxide solution, and S is the sample (g).)

[0190] <Calculation method for shell thickness in core-shell structure> In the calculation method for the number of microdomains and the number-average particle size of the major axis, the shell is defined as a portion that does not contain crystalline material in an area that is 25% or less of the distance from the contour of the cross section of the crystalline material of the toner to the center of gravity of the cross section. The cross sections of 100 or more toner particles were observed, and the average value of the distance from the contour to the area that does not contain crystalline material was calculated, and this value was defined as the thickness of the shell.

[0191] <Method of measuring weight average particle size (D4) of toner> The weight-average particle diameter (D4) of the toner was measured with an effective measurement channel count of 25,000 channels using a precision particle size distribution measuring device equipped with a 100 μm aperture tube and a fine hole electrical resistance method, called "Coulter Counter Multisizer 3" (registered trademark, manufactured by Beckman Coulter, Inc.), and the accompanying dedicated software "Beckman Coulter Multisizer 3 Version 3.51" (manufactured by Beckman Coulter, Inc.), for setting measurement conditions and analyzing measurement data. The weight-average particle diameter (D4) of the toner was calculated by analyzing the measurement data.

[0192] The electrolyte solution used for the measurement is prepared by dissolving special grade sodium chloride in ion-exchanged water to a concentration of approximately 1% by mass, for example, "ISOTON II" (manufactured by Beckman Coulter).

[0193] Before carrying out the measurements and analyses, the dedicated software was set up as follows.

[0194] In the "Change Standard Measurement Method (SOM) screen" of the dedicated software, set the total count number in the 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" (Beckman Coulter). Press the threshold / noise level measurement button to automatically set the threshold and noise level. In addition, set the current to 1600 μA, the gain to 2, the electrolyte to ISOTON II, and check the aperture tube flush after measurement.

[0195] In the "Pulse to particle size conversion setting screen" of the dedicated software, set the bin interval to logarithmic particle size, the particle size bin to 256 particle size bins, and the particle size range from 2 μm to 60 μm.

[0196] The specific measurement method is as follows. 1. Pour about 200 ml of the electrolyte solution into a 250 ml round-bottom glass beaker made exclusively for the Multisizer 3, set it on the sample stand, and stir the stirrer rod counterclockwise at 24 revolutions per second. Then, use the "aperture flush" function of the analysis software to remove dirt and air bubbles from inside the aperture tube. 2. Place approximately 30 ml of the above electrolyte solution in a 100 ml flat-bottom glass beaker, and add approximately 0.3 ml of a solution prepared by diluting "Contaminon N" (a 10% by weight aqueous solution of a neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, with a pH of 7, manufactured by Wako Pure Chemical Industries, Ltd.) three times by weight with ion-exchanged water as a dispersant. 3. A specified amount of ion-exchanged water is placed in the water tank of an ultrasonic disperser "Ultrasonic Dispersion System Tetora150" (manufactured by Nikkaki Bios) that has two oscillators with an oscillation frequency of 50 kHz built in with a phase shift of 180 degrees and an electrical output of 120 W, and approximately 2 ml of the above-mentioned Conaminon N is added to this water tank. 4. Set the beaker from step 2 in 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 electrolyte solution level in the beaker is maximized. 5. While the electrolyte solution in the beaker in step 4 is being irradiated with ultrasonic waves, about 10 mg of toner is added little by little to the electrolyte solution and dispersed. Then, ultrasonic dispersion treatment is continued for another 60 seconds. During ultrasonic dispersion, the water temperature in the water tank is appropriately adjusted to be between 10°C and 40°C. 6. Using a pipette, add the electrolyte solution (5) in which the toner has been dispersed, to the round-bottom beaker (1) placed in the sample stand, and adjust the measurement concentration to about 5%. Then, measurements are continued until the number of particles measured reaches 50,000. 7. Analyze the measurement data using the dedicated software that comes with the device and calculate the weight-average particle size (D4). Note that when the dedicated software is set to Graph / Volume%, the "Arithmetic diameter" on the Analysis / Volume Statistics (Arithmetic Mean) screen is the weight-average particle size (D4).

[0197] [Configuration included in the embodiment of the present invention] The disclosure of this embodiment includes the following configuration. (Configuration 1) A toner having toner particles containing a binder resin and silica aggregate particles, In a TOF-SIMS measurement of the toner particles, a fragment peak derived from a boron atom and a fragment peak derived from a boron-oxygen structure are detected, The silica agglomerated particles are agglomerates of silica fine particles having a number-based primary particle size of 20 nm or more and 75 nm or less, The maximum Feret diameter of the silica agglomerated particles is 110 nm or more and 500 nm or less, the aspect ratio of the silica agglomerated particles is 1.50 or more and 4.00 or less; The toner is characterized in that when the silica aggregate particles are dispersed in a solvent and titrated with an aqueous NaOH solution, the following formula (1) is satisfied: 0.01≦{(ab)×c×NA} / (d×e)≦0.20···(1) (In formula (1), a is the titration amount (L) of NaOH aqueous solution required to adjust a mixture of 25.0 g of ethanol in which silica agglomerated particles are dispersed and 75.0 g of 20 mass % NaCl aqueous solution to pH 9. b is the titer (L) of NaOH solution required to adjust a mixture of 25.0 g of ethanol and 75.0 g of 20% NaCl solution to pH 9. c is the concentration (N) of the NaOH aqueous solution used in the titration. NA is Avogadro's number. d is the mass of the silica agglomerated particles (g). e is the BET specific surface area (nm 2 / g). (Configuration 2) The toner according to configuration 1, wherein the amount (by mass) of boron atoms present in the toner as measured by an inductively coupled plasma mass spectrometer (ICP-MS) is 0.1 ppm or more and 2.00 ppm or less. (Configuration 3) The toner according to configuration 1 or 2, wherein the coverage of the silica aggregate particles with respect to the toner particles is 0.5% or more and 10.0% or less. (Configuration 4) The toner according to any one of Configurations 1 to 3, wherein the dispersibility evaluation index of the silica aggregate particles on the surface of the toner particles is 2.00 or less. (Configuration 5) The toner according to any one of Configurations 1 to 4, wherein the toner further contains titanium oxide particles that satisfy the following (i) and (ii), in addition to the silica aggregate particles: (i) the maximum Feret diameter is 300 nm or more and 3000 nm or less; (ii) Aspect ratio is 5.0 or more (Configuration 6) The amount of boron atoms present (by mass) in the toner is B (ppm), and the amount of silanol defined by the following formula (2) when the silica aggregate particles are dispersed in a solvent and titrated with the NaOH aqueous solution is S (silanol / nm 2 6. The toner according to any one of configurations 1 to 5, wherein, when B and S satisfy the following formula (3): S={(ab)×c×NA} / (d×e)···(2) 0.03≦S / B≦20.0 (3) (Configuration 7) The toner according to any one of Configurations 1 to 6, wherein the toner has an average circularity of 0.960 or more and 0.990 or less. (Configuration 8) The toner according to any one of Configurations 1 to 7, which has a shell layer on a surface of the toner particle, the shell layer present on the surface of the toner particle contains a polyester resin, the shell layer does not contain a crystalline material in a cross section of the toner particle observed with a transmission electron microscope, and when the thickness of the shell layer is T (nm), the following formula (4) is satisfied: 300≦T≦700 (4) (Configuration 9) The toner according to any one of Configurations 1 to 8, wherein the toner particles contain dodecylbenzenesulfonic acid or a dodecylbenzenesulfonate salt. EXAMPLES

[0198] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is in no way limited thereto. Parts used in the examples are by weight unless otherwise specified.

[0199] <Production Example of Silica Aggregated Particles 1> 60 kg / h of silicon tetrachloride (SiCl4) and 50 m 3 / h (standard conditions) of hydrogen (primary combustible gas) and 33 m 3 / h (standard condition) of oxygen (primary oxygen-containing gas) is introduced into the mixing chamber of the combustion burner and mixed, and this mixed gas is sprayed from the burner, ignited and burned in the reaction chamber, retained in the mixing chamber for 0.001 seconds, and then sprayed for a further 20 m 3 / h (standard conditions) of hydrogen (primary combustible gas) and 30m 3 / h (standard condition) of oxygen (primary oxygen-containing gas) was additionally supplied and the mixture was allowed to remain in the tank for 0.020 seconds. The resulting silica powder was collected using a filter.

[0200] The obtained silica base particles (BET specific surface area: 15.4 m 2A solution of 1 part hexamethyldisilazane diluted with 100 parts hexane was added with stirring under nitrogen purging, and treatment was carried out at the reaction temperature and for the reaction time shown in the treatment conditions while continuing to stir, thereby obtaining silica agglomerated particles 1.

[0201] The obtained silica agglomerated particles 1 had a number-based primary particle size of 30 nm, a maximum Feret diameter of 290 nm, an aspect ratio of 2.10, and a silanol amount defined by formula (1) of 0.15. The physical properties of silica agglomerated particles 1 are shown in Table 1.

[0202] <Production Examples of Silica Aggregated Particles 2 to 16> Silica agglomerated particles 2 to 16 were produced in the same manner as in the production example of silica agglomerated particles 1, except that the production example of silica base particles (flow rate of silicon tetrachloride, flow rate of hydrogen gas, flow rate of oxygen gas, silica concentration, and residence time) and the surface treatment conditions of the silica agglomerated particles (type of surface treatment agent, amount added, reaction temperature, and reaction time) in the production example of silica agglomerated particles 1 were changed as shown in Table 1. The physical properties of silica agglomerated particles 2 to 16 are shown in Table 1.

[0203] [Table 1]

[0204] <Production Examples of Titanium Oxide Particles 1 to 5> Titanium oxide particles were produced as follows. A 50% NaOH aqueous solution was added to metatitanic acid obtained by the sulfuric acid method in an amount four times the molar amount of NaOH relative to TiO2, and the mixture was heated at 95°C for 2 hours. After thorough washing, 31% HCl was added so that the HCl / TiO2 ratio became 0.26, and the mixture was heated at the boiling point for 1 hour. After cooling, the mixture was neutralized to pH 7 with 1 mol / L NaOH, washed and dried to produce titanium oxide microparticles. The specific surface area of ​​the obtained titanium oxide microparticles was 115 g / m 2 It was.

[0205] To 100 parts of this titanium oxide fine particle, 100 parts of NaCl and 25 parts of Na2P2O7·10H2O were added and mixed in a vibrating ball mill for 1 hour, and the mixture was fired at 850°C for 2 hours in an electric furnace. The fired product obtained was placed in pure water and heated at 80°C for 6 hours, and then washed to remove soluble salts. All of the particles obtained after drying had a minor axis in the range of 0.03 μm to 0.07 μm and a major axis in the range of 0.4 μm to 0.8 μm, giving titanium oxide particles 1 to 5. The physical properties of titanium oxide particles 1 to 5 are shown in Table 2.

[0206] [Table 2]

[0207] <Production Example of Polyester Resin 1> The following materials were mixed in a reaction vessel equipped with a nitrogen inlet line, a dehydration line, and a stirrer, and 100 parts of the mixture and 0.52 parts of tin di(2-ethylhexanoate) as a catalyst were placed in a polymerization tank. Terephthalic acid 45.0 parts Bisphenol A without ethylene oxide 53.0 parts

[0208] Next, after the inside of the polymerization tank was filled with nitrogen, the polycondensation reaction was carried out for 6 hours while heating at 200°C. After the temperature was further increased to 210°C, 2.0 parts of trimellitic anhydride was added, and the inside of the polymerization tank was depressurized to 40 kPa, after which the condensation reaction was further carried out. The obtained polyester resin had an acid value of 6.0 mgKOH / g and a weight average molecular weight (Mw) of 12,400.

[0209] <Production example of styrene acrylic resin 1> The following materials were mixed in a reaction vessel equipped with a cooling tube, a stirrer, and a nitrogen inlet tube, and the temperature was raised and maintained at 180°C while stirring. Styrene 77.0 parts n-Butyl acrylate 21.0 parts Acrylic acid 2.0 parts 300.0 parts xylene

[0210] Next, 50.0 parts of a 2.0 mass% xylene solution of t-butyl hydroperoxide was continuously dropped into the system over 4.5 hours, and after cooling, the solvent (xylene) was separated and removed to synthesize styrene acrylic resin 1. The obtained styrene acrylic resin had a weight average molecular weight Mw of 14,500 and a Tg of 65°C.

[0211] "Preparation of resin particle dispersion 1" Styrene acrylic resin 1 100 parts Methyl ethyl ketone 50 parts 20 parts isopropyl alcohol Methyl ethyl ketone and isopropyl alcohol were added to the container. The resin was then gradually added, stirred, and completely dissolved to obtain a styrene acrylic resin 1 solution. The container containing the styrene acrylic resin 1 solution was set to 65°C, and a total of 5 parts of 10% aqueous ammonia was gradually added dropwise while stirring, and 230 parts of ion-exchanged water was gradually added at a rate of 10 ml / min to cause phase inversion emulsification. The pressure was then reduced with an evaporator to remove the solvent, and a resin particle dispersion 1 of styrene acrylic resin 1 was obtained. The volume average particle size of the resin particles was 135 nm. The resin particle solid content was adjusted to 20% with ion-exchanged water.

[0212] "Preparation of resin particle dispersion 2" 100 parts polyester resin 1 Methyl ethyl ketone 50 parts 20 parts isopropyl alcohol Methyl ethyl ketone and isopropyl alcohol were added to the container. The above materials were then gradually added and stirred to completely dissolve, obtaining a polyester resin 1 solution. The container containing the polyester resin 1 solution was set to 40°C, and a 10% aqueous ammonia solution was gradually dripped into the container while stirring to a total of 3.5 parts, and 230 parts of ion-exchanged water were gradually dripped into the container at a rate of 10 ml / min to cause phase inversion emulsification. The pressure was further reduced to remove the solvent, obtaining a resin particle dispersion 2 of polyester resin 1. The volume average particle size of the resin particles was 155 nm. The resin particle solid content was adjusted to 20% with ion-exchanged water.

[0213] "Preparation of colorant particle dispersion" Copper phthalocyanine (pigment blue 15:3) 45 parts Ionic surfactant Neogen RK (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 5 parts 190 parts deionized water The above components were mixed and dispersed for 10 minutes using a homogenizer (IKA Ultra Turrax), and then dispersed for 20 minutes at a pressure of 250 MPa using an Ultimizer (opposed collision type wet grinder: Sugino Machine Ltd.) to obtain a colorant particle dispersion having a volume average particle size of 120 nm and a solid content of 20%.

[0214] "Preparation of release agent particle dispersion" Release agent (hydrocarbon wax, melting point: 79°C) 15 parts Ionic surfactant Neogen RK (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 2 parts 240 parts deionized water The above was heated to 100°C and thoroughly dispersed using an IKA Ultra Turrax T50, and then the mixture was heated to 115°C using a pressure discharge type Gaulin homogenizer and dispersed for 1 hour to obtain a release agent particle dispersion with a volume average particle size of 160 nm and a solid content of 20%.

[0215] <Production Example of Toner Particle 1> ·Resin particle dispersion 1 900 parts Colorant particle dispersion 50 parts Release agent particle dispersion 80 parts First, in the core formation step, the above materials were put into a round stainless steel flask and mixed. Then, the mixture was dispersed for 10 minutes at 5000 r / min using a homogenizer Ultra Turrax T50 (manufactured by IKA). After adding a 1.0% aqueous nitric acid solution and adjusting the pH to 3.0, the mixture was heated to 58°C in a heating water bath using a stirring blade while appropriately adjusting the rotation speed so that the mixture was stirred. The volume average particle size of the formed aggregated particles was appropriately confirmed using a Coulter Multisizer III, and when aggregated particles (cores) of 5.0 μm were formed, the following materials were put in and further stirred for 1 hour as the shell layer formation step to form a shell layer. ·Resin particle dispersion 2 40 parts 300 parts of ion-exchanged water ·19 parts of 10.0% by mass borax aqueous solution (Borax; Sodium tetraborate decahydrate, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.)

[0216] Thereafter, the pH was adjusted to 9.0 using a 5% aqueous solution of sodium hydroxide, and the mixture was heated to 89°C while continuing to stir. When the desired surface shape was obtained, heating was stopped, the mixture was cooled to 25°C, filtered and separated into solid and liquid, and then washed with ion-exchanged water. After washing, the mixture was dried using a vacuum dryer to obtain toner particles with a weight average particle size (D4) of 6.3 μm.

[0217] Furthermore, a 1% aqueous solution of sodium dodecylbenzenesulfonate (product name: Neogen RK (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was sprayed onto the toner so that the dodecylbenzenesulfonic acid content in the toner was 500 ppm, thereby obtaining toner particles 1.

[0218] <Production Examples of Toner Particles 2 to 11 and 13> Toner particles 2 to 11 and 13 were obtained in the same manner as in the production example of toner particle 1, except that the recipe and conditions were changed as shown in Table 3. The physical properties of the obtained toner particles 2 to 11 and 13 are shown in Table 3.

[0219] <Production Example of Toner Particles 12> (Production of toner base particles) The following materials were thoroughly mixed in an FM mixer (manufactured by Nippon Coke and Engineering Co., Ltd.), and then melt-kneaded in a twin-screw kneader (manufactured by Ikegai Iron Works Co., Ltd.) set at a temperature of 100°C. Styrene acrylic resin 1 95.0 parts Polyester resin 1 5.0 parts HNP9 (melting point: 76°C, manufactured by Nippon Seiro Co., Ltd.) 5.0 parts ·CIPigment Blue15:3 6.0 copies

[0220] The obtained kneaded product was cooled and coarsely crushed to 1 mm or less using a hammer mill to obtain a coarsely crushed product.

[0221] Next, the obtained coarsely crushed material was milled using a Turbo Mill manufactured by Turbo Kogyo Co., Ltd. to obtain finely pulverized material of about 5 μm, and then a multi-division classifier utilizing the Coanda effect was used to remove fine and coarse powder to obtain toner base particles 1. The weight average particle size (D4) of toner base particles 1 was 6.8 μm and Tg was 58° C.

[0222] (Production of toner base particle dispersion) Into a reaction vessel containing 390.0 parts of ion-exchanged water, 15.0 parts of sodium phosphate (12-hydrate) were added, and the mixture was kept at 65° C. for 1.0 hour while being purged with nitrogen.

[0223] Using a TK homomixer (manufactured by Tokushu Kika Kogyo Co., Ltd.), the mixture was stirred at 12,000 rpm. While maintaining the stirring, an aqueous calcium chloride solution in which 9.0 parts of calcium chloride (dihydrate) was dissolved in 10.0 parts of ion-exchanged water was added to the reaction vessel all at once to prepare an aqueous medium containing inorganic fine particles as a dispersant. Furthermore, 1.0 mol / L of hydrochloric acid was added to the aqueous medium in the reaction vessel to adjust the pH to 6.0, and aqueous medium 1 was prepared.

[0224] 200.0 parts of toner base particles 1 were added to the aqueous medium 1 and dispersed for 30 minutes while rotating at 7000 rpm using a TK homomixer at a temperature of 40° C. Ion-exchanged water was added to adjust the toner base particle concentration in the dispersion to 20.0%, and toner base particle dispersion 1 was obtained.

[0225] (Production of toner particles) The following samples were weighed and placed in a reaction vessel, and mixed using a propeller agitator. Toner base particle dispersion 1 500.0 parts ·Resin particle dispersion 2 10.0 parts

[0226] Next, the pH of the resulting mixture was adjusted to 4.0 using a 1 mol / L NaOH aqueous solution, and the temperature of the mixture was adjusted to 30°C, after which 1.5 parts of boric acid powder was added and the mixture was held for 1.0 hour while being mixed at 200 rpm using a propeller impeller. The temperature was then increased to 80°C at a rate of 1°C / min while being stirred with a propeller impeller, and held for 2 hours.

[0227] Subsequently, the temperature of the contents was cooled to room temperature (about 25° C.), the pH was adjusted to 1.5 with 1 mol / L hydrochloric acid, and the contents were stirred for 1.0 hour, and then the contents were washed with ion-exchanged water and filtered to obtain toner particles 12. The physical properties of the obtained toner particles 12 are shown in Table 3.

[0228] <Production Example of Toner Particle 14> Toner particles 14 were obtained in the same manner as in the production example of toner particles 12, except that the recipe and conditions were changed as shown in Table 3. The physical properties of the obtained toner particles 14 are shown in Table 3.

[0229] [Table 3]

[0230] <Toner 1 Manufacturing Example> Into an FM mixer (FM500 manufactured by Nippon Coke & Engineering Co., Ltd.), 100.0 parts of toner particles 1, 0.7 parts of silica agglomerated particles 1, and 0.2 parts of titanium oxide particles 1 were charged. Then, external addition was performed by mixing at 800 rpm for 10 minutes.

[0231] At this time, at the same time as the start of mixing, hot water and cold water were appropriately passed through the jacket to maintain the temperature inside the tank at 45°C.

[0232] Thereafter, the toner was sieved through a mesh having an opening of 75 μm to obtain Toner 1. The physical properties of Toner 1 are shown in Table 5.

[0233] <Production Examples of Toners 2 to 31> Toners 2 to 31 were obtained in the same manner as in Production Example of Toner 1, except that the type of toner particles, the type and added amount of silica aggregated particles, and the type and added amount of titanium oxide particles were changed as shown in Table 4. The physical properties of the obtained Toners 2 to 31 are shown in Table 5.

[0234] [Table 4]

[0235] [Table 5]

[0236] Example 1 The following evaluations were carried out using the above Toner 1. The evaluation results are shown in Table 6.

[0237] A modified version of the commercially available Canon laser beam printer "LBP7600C" was used. The modification involved changing the gears and software of the evaluation machine itself to set the rotation speed of the transport roller to rotate at a constant speed relative to the drum. By making the above modifications, the transfer of toner from the photoconductor to the recording medium is suppressed, making it a more severe mode for evaluating the level of transfer defects.

[0238] Next, the electrophotographic apparatus and the process cartridge were left in an environment of 15°C and 10% RH for 48 hours in order to acclimate them to the measurement environment. After leaving them, the electrophotographic apparatus and the process cartridge were printed with Business 4200 paper of LETTER size (manufactured by XEROX, 75 g / m) in the same low temperature and low humidity environment (15°C / 10% RH). 2 ) with 50 mm margins on each side, an image with a printing rate of 4.0% was printed in the center in the horizontal direction up to 20,000 sheets, and evaluation was performed on the initial image and after printing 20,000 sheets.

[0239] <Evaluation of image density> The image density was measured using a Macbeth Sales Densitometer RD918 (manufactured by Macbeth) in accordance with the attached instruction manual by measuring the relative density to the image of the white background area with an image density of 0.00, and the obtained relative density was used as the image density value.

[0240] The initial density and density after the above durability test were measured. Durability was judged by the degree of density decrease from the initial test to the end of durability test. Three solid images were printed out at the initial test and after durability test, and the average value of the central densities was used as the image density. The evaluation criteria are as follows, and C or higher was judged as good.

[0241] (Initial image density) A: Image density is 1.45 or more B: Image density is 1.40 or more and less than 1.45 C: Image density is 1.35 or more and less than 1.40 D: Image density is less than 1.35

[0242] (Image density reduction rate) The image density reduction rate was calculated using the following formula. Image density reduction rate = (Initial image density - Image density after durability) / Initial image density x 100 A: Image density reduction rate is less than 5.0% B: Image density reduction rate is 5.0% or more and less than 10.0% C: Image density reduction rate is 10.0% or more and less than 15.0% D: Image density is 15.0% or more

[0243] <Evaluation of fogging> The fogging was measured by measuring the reflectance using a REFLECTMETER MODEL TC-6DS manufactured by Tokyo Denshoku Co., Ltd. A green filter was used. The fogging was calculated from the reflectance before and after outputting a solid white image using the following formula. Fog (reflectance) (%) = Reflectance of standard paper (%) - Reflectance of solid white image sample (%)

[0244] After the durability test, fog was measured. After the durability test, three solid white images were printed, and the average fog value in the center of the images was evaluated as fog. The evaluation criteria were as follows, and a grade of C or higher was considered to be good. A: Less than 1.0% B: 1.0% or more, less than 2.0% C: 2.0% or more, less than 3.0% D: 3.0% or more

[0245] <Evaluation of the increase rate of silica aggregate particles> The initial coverage of the silica agglomerated particles and the coverage of the silica agglomerated particles after the above-mentioned durability test were measured. The increase in the silica agglomerated particles was determined from the increase in coverage of the silica agglomerated particles from the initial to the end of the durability test. The increase in the silica agglomerated particles was calculated using the following formula. Increase rate of silica agglomerated particles = (coverage rate of silica agglomerated particles after durability test - coverage rate of initial silica agglomerated particles) / coverage rate of initial silica agglomerated particles x 100

[0246] The evaluation criteria were as follows, with C or above being considered as good. A: The increase in silica aggregate particles is less than 5.0% B: The increase rate of silica aggregate particles is 5.0% or more and less than 10.0% C: The increase rate of silica aggregate particles is 10.0% or more and less than 15.0% D: The increase rate of silica aggregate particles is 15.0% or more.

[0247] <Evaluation of transfer defects> After the durability test, the amount of toner on the paper was measured. 2 The development contrast is adjusted so that the image is formed so that thin lines exist in both the vertical and horizontal directions, and two lines of 2, 4, 6, 8, and 10 dots are printed so that the width of the non-latent image area between each line is approximately 1 mm. The results are observed visually and with a 20x loupe and evaluated according to the following criteria. The evaluation criteria are as follows, and a grade of C or higher is considered good. A: In the two-dot line, almost no hollow is observed even under magnification, and cannot be confirmed by visual inspection. B: In the two-dot line, some hollows can be observed under magnification, but cannot be confirmed by the naked eye. C: Holes can be visually confirmed in the 2-dot line, but no holes can be visually confirmed in the 4-dot line. D: Hollow areas can be visually confirmed in the 4-dot line.

[0248] [Examples 2 to 25, Comparative Examples 1 to 8] The above evaluations were carried out using the above toners 2 to 33. The evaluation results are shown in Table 6.

[0249] [Table 6]

Claims

1. A toner having toner particles containing a binder resin and silica aggregate particles, In a TOF-SIMS measurement of the toner particles, a fragment peak derived from a boron atom and a fragment peak derived from a boron-oxygen structure are detected, The silica agglomerated particles are agglomerates of silica fine particles having a number-based primary particle size of 20 nm or more and 75 nm or less, The maximum Feret's diameter of the silica agglomerated particles is 110 nm or more and 500 nm or less, the aspect ratio of the silica agglomerated particles is 1.50 or more and 4.00 or less; The toner is characterized in that when the silica agglomerated particles are dispersed in a solvent and titrated with an aqueous NaOH solution, the following formula (1) is satisfied: 0.01≦{(a-b)×c×NA} / (d×e)≦0.20...(1) (In formula (1), a is the titration amount (L) of the NaOH aqueous solution required to adjust a mixed solution of 25.0 g of ethanol in which the silica agglomerated particles are dispersed and 75.0 g of a 20 mass % NaCl aqueous solution to pH 9. b is the titration amount (L) of the aqueous NaOH solution required to adjust a mixed solution of 25.0 g of ethanol and 75.0 g of a 20% by mass aqueous NaCl solution to pH 9. c is the concentration (N) of the aqueous NaOH solution used in the titration. NA is Avogadro's number. d is the mass (g) of the silica agglomerated particles. e is the BET specific surface area (nm 2 / g).

2. 2. The toner according to claim 1, wherein the amount (by mass) of boron atoms present in the toner as measured by an inductively coupled plasma mass spectrometer (ICP-MS) is 0.1 ppm or more and 2.00 ppm or less.

3. 3. The toner according to claim 1, wherein a coverage rate of the silica aggregate particles with respect to the toner particles is 0.5% or more and 10.0% or less.

4. 3. The toner according to claim 1, wherein a dispersion evaluation index of the silica aggregate particles on the surface of the toner particles is 2.00 or less.

5. 3. The toner according to claim 1, further comprising, in addition to the silica aggregate particles, titanium oxide particles which satisfy the following (i) and (ii): (i) The maximum Feret diameter is 300 nm or more and 3000 nm or less; (ii) Aspect ratio is 5.0 or more.

6. The amount of boron atoms present (by mass) in the toner is represented as B (ppm), and the amount of silanol defined by the following formula (2) when the silica aggregate particles are dispersed in a solvent and titrated with the NaOH aqueous solution is represented as S (silanol / nm 2 3. The toner according to claim 1, wherein, when B and S satisfy the following formula (3): S={(a-b)×c×NA} / (d×e)...(2) 0.03≦S / B≦20.0 (3)

7. 3. The toner according to claim 1, wherein the toner has an average circularity of 0.960 or more and 0.990 or less.

8. 3. The toner according to claim 1 or 2, which has a shell layer on a surface of the toner particle, the shell layer present on the surface of the toner particle contains a polyester resin, and in a cross section of the toner particle observed with a transmission electron microscope, the shell layer does not contain a crystalline material, and when a thickness of the shell layer is T (nm), the following formula (4) is satisfied: 300≦T≦700 (4)

9. 3. The toner according to claim 1, wherein the toner particles contain dodecylbenzenesulfonic acid or a dodecylbenzenesulfonate salt.