JP5371407B2 - Toner and toner production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a toner having superior low temperature fixability and excellent heat-resistant storage property, hardly causing a blocking phenomenon even when used in a high temperature environment, and having excellent stability of triboelectric charging. <P>SOLUTION: The toner includes toner particles comprising core particles containing at least a binder resin, a colorant and wax, and a coating layer formed by fixing resin particles on the surfaces of the core particles, and is characterized in that: the resin fine particles comprise a resin containing a functional group capable of developing self-dispersibility in at least water; a pH(a) representing an isoelectric point obtained by the measurement of a zeta potential of the resin fine particles in water is lower than a pH(b) representing an isoelectric point obtained by the measurement of a zeta potential of the core particles in water; and the zeta potential of the resin fine particles in water at pH(b) is -5.0 mV or lower. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a toner used to form a toner image by developing an electrostatic latent image formed by a method such as electrophotography, electrostatic recording, or toner jet recording, and a method for producing the same. .

  In recent years, printers and copiers are required to increase the resolution of images by digitization, and at the same time, increase the printing or copying speed, or save space and reduce power consumption by downsizing the apparatus. .

  In order to satisfy these requirements, improvement in the fixing performance of the toner itself has been demanded. That is, it is desired to realize a toner that can be fixed at a lower temperature.

  In general, toner is fine particles having a particle size of about 5 to 30 μm, mainly composed of a binder resin, a dye, a pigment, carbon black, and a colorant such as a magnetic material. Manufactured by a wet manufacturing method represented by a turbid polymerization method or a dissolution suspension method.

  The toner by the pulverization method melts and uniformly disperses the colorant and, if necessary, the charge control agent and wax in a thermoplastic resin as a binder resin, and then finely disperse the obtained resin composition. It is obtained by grinding and classifying.

  On the other hand, in the toner by the suspension polymerization method, a polymerizable monomer composition obtained by dissolving or dispersing the colorant or wax in a polymerizable monomer is placed in an aqueous medium containing a dispersion stabilizer together with a polymerization initiator. It is obtained by suspending and granulating, and polymerizing the polymerizable monomer while heating. At this time, a polyfunctional monomer, a chain transfer agent, and a charge control agent are added to the polymerizable monomer composition as necessary. Thus, polymer particles having a desired particle size can be obtained.

  In addition, the toner by the dissolution suspension method is obtained by dissolving or dispersing a binder resin, a colorant, and a wax in a solvent capable of dissolving the binder resin, and suspending it in an aqueous medium containing a dispersion stabilizer. After granulation, the solvent is removed by a method such as heating and decompression.

  As a general method for improving the low-temperature fixability of these toners, a method of lowering the glass transition temperature of a binder resin constituting the toner is known. However, simply lowering the glass transition temperature decreases the heat-resistant storage stability of the toner, and when used in a high-temperature environment, the toner that agglomerates between the toners that come into contact with each other tends to cause a blocking phenomenon. Arise. Further, there is a problem that the toner carrying member is easily contaminated and the filming on the photosensitive member is likely to occur, resulting in a deterioration in image quality.

  In order to solve these problems, a toner having a capsule structure composed of core particles containing a resin having a low glass transition temperature and a coating layer containing a resin having a high glass transition temperature formed on the surface of the core particles has been devised. Has been.

  For example, a mixed liquid of a core constituent material containing a monomer (polymerizable monomer) that is a raw material of a thermoplastic resin and an outer shell constituent material containing amorphous polyester is dispersed in a dispersion medium. In addition, a capsule toner in which an outer shell (coating layer) is formed by an in-situ polymerization method in which the outer shell constituent material is unevenly distributed on the surface of the droplet as the core particles are formed by polymerization has been proposed (see Patent Document 1). .

  Further, by adding an aqueous dispersion of resin fine particles obtained by emulsion polymerization or soap-free emulsion polymerization to polymer particles (core particles) obtained by suspension polymerization, 95% or more of the surface of the polymer particles is obtained. There has been proposed a toner which is coated with fine particles and then heated to a temperature higher than the glass transition temperature of the polymer particles so as to have a surface substantially free of bulges (see Patent Document 2).

  In addition, fine particles obtained by phase inversion emulsification of an acidic group-containing resin in the presence of a basic neutralizing agent are mixed with an aqueous dispersion of resin particles (core particles), and an acid is added to the resin particle surface to add the particles. There has been proposed a toner obtained by precipitating fine particles, removing a liquid medium, and then stirring and mixing a dried powder under heating (see Patent Document 3).

  Further, an intermediate layer having a charging property opposite to that of the toner inner particle is formed on the surface of the toner inner particle (core particle), and a resin (resin fine particle) having a charging property opposite to that of the intermediate layer is formed on the surface of the intermediate layer. A toner in which an outer shell layer (coating layer) is formed is disclosed (see Patent Document 4).

  Among the above-described conventional examples, the toner disclosed in Patent Document 1 utilizes the property that separation occurs in the liquid droplets of the mixed liquid due to the difference in solubility index between the core material and the outer shell material. Thus, an outer shell is formed, and a layer having a substantially uniform thickness is formed. However, the heat-resistant storage stability of the toner having the outer shell formed in this way is not necessarily sufficient, and in the case of core particles having a low glass transition temperature that actually satisfies the low-temperature fixability, in order to obtain sufficient heat-resistant storage stability. It is necessary to add a large amount of amorphous polyester as the outer shell constituent material. As a result, since the viscosity of the droplets is remarkably increased during granulation, there is a problem that manufacturing stability is impaired.

  Further, the toner disclosed in Patent Document 2 described above has a sufficient mechanical strength because the surface thereof is smooth without any protrusion. However, when heating is performed excessively in order to obtain such a smooth surface, a part of the resin fine particles attached to the surface of the core particle may be buried inside the core particle. As a result, the core particles were partially exposed, or a part of the contained wax oozed out, so that sufficient heat-resistant storage stability could not be obtained. On the other hand, when heating is performed under milder conditions in order to avoid such a problem, the surface smoothness is lowered and sufficient mechanical strength cannot be obtained. Peeling and falling off easily occurred, and sufficient heat resistant storage stability could not be obtained. In addition, it is difficult to obtain a stable triboelectric charge property with such a toner having poor surface smoothness.

  Further, the toner disclosed in Patent Document 3 described above is one in which an acid is added to an aqueous dispersion to precipitate the fine particles on the surface of the core particles, thereby forming a resin fine particle layer. However, in this method, the fine particles easily aggregate together, and the state of precipitation on the surface of the core particles is not necessarily uniform. In addition, since the fine particles that have been deposited may fall off due to filtration and drying without heat treatment, a toner having sufficient blocking resistance even when the powder thus obtained is stirred and mixed under heating. It was difficult to get. Further, since the smoothness of the toner surface is inferior, it is difficult to obtain a stable triboelectric chargeability.

  Further, the toner disclosed in Patent Document 4 described above is obtained by forming an intermediate layer by adhering inorganic fine particles such as tricalcium phosphate or organic fine particles such as benzoguanamine to a dispersion of core particles, The outer shell layer is formed by attaching fine particles. Such a toner production method is not only complicated in process, but particularly when inorganic fine particles are used as the intermediate layer, the fixing strength of each layer may not be sufficient, which may cause peeling or dropping, and sufficient blocking resistance. It was difficult to obtain a toner having the properties.

As described above, in a toner having a capsule structure composed of core particles having a low glass transition temperature and a coating layer having a high glass transition temperature, low temperature fixability, heat resistant storage stability, and friction stability without impairing production stability. It is difficult to produce a toner that combines properties.
Special registration 03030741 JP 2000-112174 A JP 2000-347455 A Japanese Patent Laid-Open No. 2003-091093

  An object of the present invention is to provide a toner and a method for producing the same that solve the above-described conventional problems.

  That is, an object of the present invention is a toner having excellent low-temperature fixability, excellent heat-resistant storage stability, hardly causing a blocking phenomenon even in use in a high-temperature environment, and excellent in frictional charging stability. And a manufacturing method capable of obtaining such a toner.

The present invention includes a step of producing core particles containing at least a binder resin, a colorant, and a wax in an aqueous medium, adding resin fine particles to a dispersion in which the core particles are dispersed, and adding the resin fine particles to the core particles. A method for producing a toner having a step of adhering to the surface of the toner,
The resin fine particles have self-dispersibility in water;
The pH (a) indicating the isoelectric point determined by measuring the zeta potential in water of the resin fine particles is smaller than the pH (b) indicating the isoelectric point determined by measuring the zeta potential in water of the core particle,
the zeta potential of the resin fine particles in water at pH (b) is −5.0 mV or less,
In the step of attaching the resin fine particles to the surface of the core particles, the dispersion fine particles are adjusted so that the pH of the dispersion is higher than pH (a) -0.30 and lower than pH (b). The present invention relates to a method for producing toner, characterized by being adhered to the surface of particles.

  The present invention also relates to a toner manufactured by the toner manufacturing method as described above.

  According to the production method of the present invention, a toner in which a uniform coating layer is formed on the entire surface of the core particle with a small amount of resin fine particles can be obtained. As a result, it is possible to provide a toner having excellent low-temperature fixability, excellent heat-resistant storage stability, hardly causing a blocking phenomenon even when used in a high-temperature environment, and having excellent frictional charging stability. it can.

  Hereinafter, the present invention will be described in more detail with reference to preferred embodiments.

  In a capsule structure toner in which a coating layer made of resin fine particles is provided on the surface of colored particles serving as core particles, the present inventors have described the core particles and the resin as factors that affect the adhesion of the coating layer to the core particles. We focused on the zeta potential when the fine particles were dispersed in water. When the zeta potential value at a specific pH of the core particles and the resin fine particles and the pH value indicating the isoelectric point obtained from the zeta potential measurement satisfy a specific relationship, the adhesion of the coating layer is greatly improved. I found out that

  That is, the pH (a) indicating the isoelectric point determined by measuring the zeta potential in water of the resin fine particles is smaller than the pH (b) indicating the isoelectric point determined by measuring the zeta potential in water of the core particle, and It was found that when the zeta potential of the resin fine particles in water at pH (b) is −5.0 mV or less, a homogeneous and strong coating layer can be formed.

  In the present invention, the resin fine particles are required to have self-dispersibility in a dispersion in which core particles are dispersed. For this purpose, the resin fine particles preferably have a polar functional group. Examples of polar functional groups that cause the resin fine particles to exhibit self-dispersibility in a dispersion include functional groups such as carboxylic acid groups, sulfonic acid groups, and phosphoric acid groups, or salts thereof.

  As a method of fixing such resin fine particles to the surface of the core particle, the pH of the aqueous medium is adjusted in a state in which these particles are dispersed in the aqueous medium, and the dispersion state of the resin fine particles is controlled. A general method is to heat-treat after adhering to the surface of the core particles.

  In the production method of the present invention, the pH (a) indicating the isoelectric point determined by the zeta potential measurement of the resin fine particles is smaller than the pH (b) indicating the isoelectric point determined by the zeta potential measurement of the core particle. is necessary. If the pH (a) is equal to or higher than pH (b), the resin fine particles are aggregated in the step of attaching the resin fine particles to the surface of the core particles, so that the core particles can be satisfactorily covered with the resin fine particles. Can not.

  Usually, the zeta potential of the core particles and resin fine particles in water shows a negative value in the pH range near neutrality. That is, if the pH (a) is smaller than the pH (b), the surface charge of the resin fine particles retains a negative charge at the pH (b) in which the zeta potential value of the core particle is 0 mV in the aqueous medium described above. When the zeta potential value of the resin fine particles is pH (a) at 0 mV, the surface charge of the core particles changes to a positive charge.

  That is, an electrical attractive force acts between the core particles and the resin fine particles under the condition that the resin fine particles lose their dispersibility in water. It is considered that this makes it possible to uniformly cover the surface of the core particle with the resin fine particles while suppressing aggregation of the resin fine particles.

  In the present invention, the zeta potential of the resin fine particles in water at pH (b) is −5.0 mV or less. Since the core particle and the resin fine particle have the largest change in zeta potential near their respective isoelectric points, the difference in zeta potential between the core particle and the resin fine particle is maximized at pH (a) to pH (b). Become. Here, the difference in zeta potential represents the difference in the surface charge density of each particle, and represents the strength of the above-described electric attractive force. Therefore, if the zeta potential of the resin fine particles in water at pH (b) is −5.0 mV or less, at least in the aqueous medium in the vicinity of pH (a) to pH (b), the core particles are between the resin fine particles. Sufficient adhesion can be obtained. Conversely, if the zeta potential of the resin fine particles in water at pH (b) is greater than −5.0 mV, it is difficult to obtain sufficient adhesion between the core particles and the resin fine particles.

  From the viewpoint of adhesion between the core particles and the resin fine particles, it is desirable that the difference in zeta potential is larger, and it is considered that a strong coating layer is formed. Accordingly, the zeta potential of the resin fine particles in water at pH (b) is more preferably -10.0 mV or less.

  In the toner production method of the present invention, core particles containing at least a binder resin, a colorant, and a wax are manufactured in an aqueous medium, and resin fine particles are added to a dispersion in which the core particles are dispersed. It is attached to the surface of the particles. Furthermore, it is necessary to adjust the pH of the dispersion when the resin fine particles are adhered to the surface of the core particle to be larger than pH (a) -0.30 and smaller than pH (b).

  As the pH of the dispersion approaches the isoelectric point (pH (b)) of the core particles, an electric attractive force acts between the core particles and the resin fine particles. Therefore, by adjusting the dispersion to a pH lower than pH (b), the resin fine particles can be smoothly adhered to the surface of the core particles, and the entire core particles can be coated with the resin fine particles without unevenness. Further, in order to eliminate unaggregated resin fine particles and to make sure that they adhere to the surface of the core particles, it is more preferable to adjust the pH of the dispersion to be smaller than pH (a).

  However, if the pH of the dispersion is excessively reduced, the fine resin particles once adhered may be detached from the surface of the core particles. This is thought to be because electrical repulsion occurs when both the core particles and the resin fine particles turn positive. Therefore, the pH of the dispersion needs to be higher than pH (a) -0.30. By doing so, it is possible to prevent the resin fine particles from being liberated and to coat the entire core particle without any unevenness.

  In the present invention, as a method for fixing the resin fine particles to the surface of the core particle, it is more preferable to use the following method.

  That is, after preparing the core particles in the aqueous medium in which the dispersion stabilizer is dispersed, the resin fine particles are added to the aqueous medium, and the resin fine particles are once attached to the core particles with the dispersion stabilizer attached to the surface. In this method, the dispersion stabilizer is dissolved and removed by adjusting the pH under heating.

  According to the above method, since the dispersion stabilizer having the positive polarity exists on the surface of the core particles having the negative polarity, the negative electrode resin fine particles can be more uniformly attached by the electric action.

  Incidentally, the adhesion between the core particles and the resin fine particles after the dispersion stabilizer is removed depends on the surface charge of each particle.

  Therefore, in order to obtain high adhesion between the core particle and the resin fine particle, the surface of the resin fine particle retains a negative charge at the pH when the dispersion stabilizer dissolves and the electric binding force disappears. In addition, it is preferable that the surface charge of the core particle is changed to a positive charge.

That is, when the pH at which the dispersion stabilizer is dissolved is pH (c), the pH (c) indicates the isoelectric point of the resin fine particles and the pH (b) indicates the isoelectric point of the core particles. Preferably satisfies the following relational expression (1). Thereby, even after the dispersion stabilizer is dissolved, the core particles and the resin fine particles can be stably adhered, so that a more uniform and strong coating layer can be formed.
Relational expression (1) pH (a) <pH (c) <pH (b)
When the core particles are produced using the dispersion stabilizer as described above, it is preferable to adjust the dispersion so that the pH of the dispersion is less than pH (c) in the step of fixing the resin fine particles to the surface of the core particles. By doing so, the dispersion stabilizer adhering to the surface of the core particles can be dissolved, and a toner having a uniform coating layer can be obtained.

  In the present invention, it is particularly preferable to use resin fine particles composed of a resin containing at least a sulfonic acid group and a carboxylic acid group as the resin fine particles.

  The sulfonic acid group has a high polarity, and the pH (a) indicating the isoelectric point of the resin fine particles can be lowered. Furthermore, at the isoelectric point pH (b) of the core particles, the zeta potential of the resin fine particles can be lowered, and as a result, high adhesion can be obtained between the core particles. However, when a coating layer is formed using resin fine particles containing only sulfonic acid groups, it is difficult to obtain toner particles having excellent surface smoothness, and stable triboelectric charging is obtained when heat treatment is insufficient. Sexuality may not be obtained. Moreover, when heat processing is performed excessively in order to improve the smoothness of a surface, particle | grains may cause aggregation.

  On the other hand, resin fine particles having a carboxylic acid group can easily obtain toner particles having high surface smoothness when a coating layer is formed, but also have a property of easily causing aggregation of particles. In addition, since the pH (a) indicating the isoelectric point becomes high and the zeta potential at the isoelectric point pH (b) of the core particles cannot be lowered, sufficient adhesion between the core particles can be obtained. Have difficulty.

  The present inventors have found that by using resin fine particles having both a sulfonic acid group and a carboxylic acid group, a capsule structure toner having excellent adhesion to the core particle and smoothness of the toner particle surface can be obtained. . Although the detailed mechanism of action is unclear, the effect up to this point is not manifested simply by using resin fine particles containing only sulfonic acid groups and resin fine particles containing only carboxylic acid groups. It is considered necessary to coexist at the molecular level.

  When resin fine particles having both sulfonic acid groups and carboxylic acid groups are used as described above, the acid value derived from the sulfonic acid groups of the resin fine particles is preferably 2.0 to 15.0 mg KOH / g, The acid value derived from the group is preferably 3.0 to 20.0 mgKOH / g, and the sum of the acid value derived from the sulfonic acid group and the acid value derived from the carboxylic acid group is 8.0 to 30. It is preferably 0 mg KOH / g.

  When the acid value derived from the sulfonic acid group is smaller than 2.0 mgKOH / g, the pH (a) indicating the isoelectric point of the resin fine particles is high, so the difference from the pH (b) is small. There is not a sufficient difference in zeta potential between the two and it is difficult to obtain adhesion between them. Further, when the acid value derived from the sulfonic acid group is larger than 15.0 mgKOH / g, not only it becomes difficult to increase the smoothness of the toner particle surface, but also the hygroscopicity when it is made into a toner is increased. Since the stability of frictional charging may be impaired, it is not preferable.

  When the acid value derived from the carboxylic acid group is smaller than 3.0 mgKOH / g, the effect of improving the smoothness of the toner particle surface cannot be obtained. On the other hand, when the acid value derived from the carboxylic acid group is larger than 20.0 mgKOH / g, the hygroscopicity when the toner is formed increases, and the stability of triboelectric charging may be impaired.

  Furthermore, when the sum of the acid value derived from the sulfonic acid group and the acid value derived from the carboxylic acid group is smaller than 8.0 mgKOH / g, fine particles having sufficient self-water dispersibility cannot be obtained. Further, when the sum of the acid value derived from the sulfonic acid group and the acid value derived from the carboxylic acid group is larger than 30.0 mgKOH / g, the hygroscopicity when the toner is formed increases, and the stability of the triboelectric charge is impaired. This is not preferable.

  The acid value referred to here represents the content of the functional group. When the functional group is in a salt state, the acid value is indicated as a value when the acid state is restored.

  As described above, the present invention provides a capsule-structure toner manufacturing method in which a coating layer of resin fine particles is provided on the surface of core particles, and the zeta potential under specific conditions of core particles and resin fine particles, which has not been considered in the past. The relationship with the isoelectric point obtained from the zeta potential measurement is specified. Further, in view of the smoothness of the surface of the obtained toner, the type and amount of the functional group of the resin fine particles to be used are defined.

  Therefore, it is difficult to achieve the object of the present invention with the conventional technique of simply fixing the resin fine particles, which is different from the conventional toner thus obtained. .

  As described above, according to the present invention, it has excellent low-temperature fixability, excellent heat-resistant storage stability, hardly causes a blocking phenomenon even in use under a high-temperature environment, and further has a frictional charging stability. In addition, an excellent toner can be realized.

  Here, the zeta potential of the core particles and the resin fine particles can be measured as follows using an ultrasonic zeta potential measuring device DT-1200 (manufactured by Dispersion Technology).

  First, pure water is prepared as a dispersion medium, and 0.5% by mass of core particles or resin fine particles are added thereto. At this time, if necessary, an appropriate amount of a nonionic surfactant that does not affect the zeta potential can be added. Next, after dispersing for 3 minutes using an ultrasonic disperser, stirring is performed while degassing for 10 minutes to obtain a dispersion of core particles or resin fine particles. About each dispersion liquid obtained in this way, a zeta potential is measured using the said apparatus. At this time, the pH of the dispersion is also measured.

  Next, an appropriate amount of a 1 mol / l hydrochloric acid aqueous solution (if necessary, a 1 mol / liter potassium hydroxide aqueous solution) is added to the dispersion to adjust the pH of the dispersion to about 0.5, and the same. To measure the zeta potential. Thereafter, this operation is repeated while sequentially changing the pH of the dispersion by about 0.5 until the zeta potential value turns positive.

  The pH and the zeta potential value thus obtained are plotted on a graph, and each plot is connected to create a pH-zeta potential curve. The pH value when the zeta potential is 0 mV is determined from the prepared pH-zeta potential curve, and this is defined as the pH indicating the isoelectric point.

  The pH at which the dispersion stabilizer is completely dissolved is, for example, when tricalcium phosphate is used as a dispersion stabilizer, an aqueous medium in which a colloid of tricalcium phosphate at a predetermined concentration is dispersed, and the acid is added dropwise with stirring. Then, the pH at which the white turbidity of the colloidal particles disappears may be obtained. When it is desired to obtain in more detail, the amount of acid dropped and the pH of the aqueous medium at that time can be plotted on a graph to create a dissolution curve, and the inflection point indicating the end of dissolution can be read from the graph.

  The acid value of the resin fine particles is represented by the amount of potassium hydroxide required to neutralize the functional group contained in 1 g of the resin, and is determined by the following method.

  The basic operation is based on JISK-0070. This method is particularly suitable for obtaining an acid value derived from a carboxylic acid group.

  1) First, 0.5 to 2.0 g of the sample is precisely weighed in a 300 ml beaker, and the mass at this time is defined as Wg. When the functional group of the sample is in a salt state, a sample that has been returned to an acid state in advance is used.

  2) To this, 150 ml of a mixed solution of toluene / ethanol (4/1) is added and dissolved.

  3) Titrate with 0.1 mol / l KOH ethanol solution. The titration can be performed, for example, using automatic titration using a potentiometric titration measuring device AT-400 (winworkstation) manufactured by Kyoto Electronics Co., Ltd. and an ABP-410 electric burette.

  4) The consumption of the KOH solution at this time is Sml. At the same time, a blank is measured, and the consumption of KOH at this time is defined as Bml.

5) Calculate the acid value according to the following formula. In the formula, f is a factor of KOH.
Acid value (mgKOH / g) = {(SB) × 0.1f × 56.1} / W
Moreover, when calculating | requiring the acid value derived from the sulfonic acid group in resin fine particles, quantitative analysis of S element is performed, for example using a fluorescent X ray analyzer (XRF), and the functional group equivalent contained in 1g of resin is water. It can be calculated in terms of the amount of potassium oxide. The measurement method conforms to JIS K 0119-1969, and is specifically as follows.

  As a measuring device, wavelength dispersion type X-ray fluorescence analyzer “Axios” (manufactured by PANalytical) and attached dedicated software “SuperQ ver. 4.0F” (manufactured by PANalytical) for setting measurement conditions and analyzing measurement data ) Is used. Rh is used as the anode of the X-ray tube, the measurement atmosphere is vacuum, the measurement diameter (collimator mask diameter) is 27 mm, and the measurement time is 10 seconds. Further, when measuring a light element, it is detected by a proportional counter (PC), and when measuring a heavy element, it is detected by a scintillation counter (SC).

  As a measurement sample, about 4 g of resin fine particles are put in a dedicated aluminum ring for press and leveled, and using a tablet molding compressor “BRE-32” (manufactured by Maekawa Tester), at 20 MPa, Pellets formed by pressing for 60 seconds and having a thickness of about 2 mm and a diameter of about 39 mm are used.

  Measurement is performed under the above conditions, the element is identified based on the obtained X-ray peak position, and the concentration (mass%) is calculated from the count rate (unit: cps) which is the number of X-ray photons per unit time. calculate.

In the toner of the present invention, the smoothness of the surface of the toner particles can be used as an index by determining the BET specific surface area. That is, the BET specific surface area S (m ² / g) of the toner particles to which the resin fine particles are fixed and the BET specific surface area S ₀ (m ² / g) of the core particles used therefor are measured, and the ratio S / S ₀ Is calculated. At this time, it can be judged that the surface smoothness is higher as the value of S / S ₀ is closer to 1.00. This index is particularly effective when substantially spherical core particles are used. Here, “substantially spherical” means that the value of average circularity described later is 0.970 or more.

  The measurement is performed as follows according to JIS Z8830 (2001).

  As a measuring device, an automatic specific surface area / pore distribution measuring device TriStar 3000 (manufactured by Shimadzu Corporation) which employs a gas adsorption method by a constant volume method as a measuring method is used. Setting of measurement conditions and analysis of measurement data are performed using dedicated software “TriStar3000 Version 4.00” attached to the apparatus, and a vacuum pump, a nitrogen gas pipe, and a helium gas pipe are connected to the apparatus. The value calculated by the BET multipoint method using nitrogen gas as the adsorption gas is defined as the BET specific surface area in the present invention.

  The BET specific surface area is calculated as follows.

First, nitrogen gas is adsorbed on toner particles (or core particles), and the equilibrium pressure P (Pa) and nitrogen adsorption amount Va (mol / g) in the sample cell at that time are measured. The relative pressure Pr, which is a value obtained by dividing the equilibrium pressure P (Pa) in the sample cell by the saturated vapor pressure Po (Pa) of nitrogen, is plotted on the horizontal axis, and the nitrogen adsorption amount Va (mol / g) is plotted on the vertical axis. An adsorption isotherm is obtained. Next, a monomolecular layer adsorption amount Vm (mol / g), which is an adsorption amount necessary for forming a monomolecular layer on the surface of toner particles (or core particles), is obtained by applying the following BET equation.
Pr / Va (1-Pr) = 1 / (Vm * C) + (C-1) * Pr / (Vm * C)
(Here, C is a BET parameter, which is a variable that varies depending on the measurement sample type, adsorbed gas type, and adsorption temperature.)

The BET equation is interpreted as a straight line with an inclination of (C-1) / (Vm × C) and an intercept of 1 / (Vm × C), where Pr is X axis and Pr / Va (1-Pr) is Y axis. Yes (this line is called a BET plot).
Straight line slope = (C-1) / (Vm × C)
Straight line intercept = 1 / (Vm × C)
When the measured value of Pr and the measured value of Pr / Va (1-Pr) are plotted on a graph and a straight line is drawn by the least square method, the slope and intercept value of the straight line can be calculated. Vm and C can be calculated by solving the above slope and intercept simultaneous equations using these values.

Further, the BET specific surface area S (m ² / g) is calculated from the Vm calculated above and the molecular occupation cross-sectional area (0.162 nm ² ) of the nitrogen molecule based on the following formula.
S = Vm × N × 0.162 × 10 ⁻¹⁸
(N is Avogadro's number (mol ⁻¹ ).)
The measurement using this apparatus follows the “TriStar 3000 Instruction Manual V4.0” attached to the apparatus, and specifically, the measurement is performed according to the following procedure.

  Thoroughly weigh the tare of a dedicated glass sample cell (stem diameter 3/8 inch, volume about 5 ml) that has been thoroughly cleaned and dried. Then, about 1.5 g of toner particles (or core particles) are put into the sample cell using a funnel.

  This sample cell is set in a “pretreatment device Bacuprep 061 (manufactured by Shimadzu Corporation)” connected with a vacuum pump and a nitrogen gas pipe, and vacuum degassing is continued at 23 ° C. for about 10 hours. During vacuum degassing, the toner particles (or core particles) are gradually degassed while adjusting the valve so that the toner particles (or core particles) are not sucked into the vacuum pump. The pressure in the cell gradually decreases with deaeration and finally becomes about 0.4 Pa (about 3 mTorr). After completion of vacuum degassing, nitrogen gas is gradually injected to return the inside of the sample cell to atmospheric pressure, and the sample cell is removed from the pretreatment device. Then, the mass of the sample cell is precisely weighed, and the exact mass of the toner particles (or core particles) is calculated from the difference from the tare. At this time, the sample cell is covered with a rubber stopper during weighing so that the toner particles (or core particles) in the sample cell are not contaminated by moisture in the atmosphere.

  Next, a dedicated “isothermal jacket” is attached to the stem portion of the sample cell containing toner particles (or core particles). Then, a dedicated filler rod is inserted into the sample cell, and the sample cell is set in the analysis port of the apparatus. The isothermal jacket is a cylindrical member having an inner surface made of a porous material and an outer surface made of an impermeable material capable of sucking liquid nitrogen to a certain level by capillary action.

  Subsequently, the free space of the sample cell including the connection tool is measured. Free space is measured by measuring the volume of the sample cell with helium gas at 23 ° C., and then measuring the volume of the sample cell after cooling the sample cell with liquid nitrogen in the same manner using helium gas. Calculated from the difference in volume. Further, the saturated vapor pressure Po (Pa) of nitrogen is automatically measured separately using a Po tube built in the apparatus.

  Next, after performing vacuum deaeration in the sample cell, the sample cell is cooled with liquid nitrogen while continuing the vacuum deaeration. Thereafter, nitrogen gas is gradually introduced into the sample cell to adsorb nitrogen molecules on the toner particles (or core particles). At this time, the adsorption isotherm is obtained by measuring the equilibrium pressure P (Pa) as needed, and the adsorption isotherm is converted into a BET plot. Note that the points of the relative pressure Pr for collecting data are set to a total of 6 points of 0.05, 0.10, 0.15, 0.20, 0.25, and 0.30. A straight line is drawn from the obtained measurement data by the least square method, and Vm is calculated from the slope and intercept of the straight line. Further, using the value of Vm, the BET specific surface area of the toner particles (or core particles) is calculated as described above.

  In the present invention, the glass transition temperature of the core particles is preferably 20 to 60 ° C. When the glass transition temperature is 20 ° C. or higher, an effect of improving heat-resistant storage stability is obtained, and when it is 60 ° C. or lower, low-temperature fixability is obtained.

  In the present invention, the glass transition temperature of the resin fine particles is preferably 10 to 50 ° C. higher than the core particles. If the difference in glass transition temperature is less than 10 ° C., a sufficient effect of improving heat-resistant storage stability cannot be obtained, and if it exceeds 50 ° C., the low-temperature fixability is impaired. A preferable glass transition temperature of the resin fine particles is 50 to 100 ° C.

  A glass transition temperature can be calculated | required as follows using the differential scanning calorimeter (2920MDSC) by TA Instruments, for example.

  First, about 6 mg of a sample is precisely weighed in an aluminum pan, and an empty aluminum pan is prepared as a reference pan. In a nitrogen atmosphere, the measurement temperature range is 20 to 150 ° C., the temperature rising rate is 2 ° C./min, and the modulation amplitude is ± 0. Measurement is performed under the conditions of 6 ° C. and a frequency of once / minute.

  From the reversing heat flow curve at the time of temperature rise obtained by measurement, draw a tangent line between the endothermic curve and the front and back baselines, find the midpoint of the straight line connecting the intersections of each tangent line, and this is the glass transition Let it be temperature.

  The core particle in this invention can be manufactured as follows, for example with a suspension polymerization method.

  First, at least a colorant and a wax are added to the polymerizable monomer that is the main constituent material of the core particles. Next, these are uniformly dissolved or dispersed using a disperser such as a homogenizer, ball mill, colloid mill, or ultrasonic disperser to prepare a polymerizable monomer composition. At this time, a polyfunctional monomer, a chain transfer agent, a charge control agent, a plasticizer, and other additives (for example, a dispersant) can be appropriately added to the polymerizable monomer composition. .

  Next, the polymerizable monomer composition is put into an aqueous medium containing a dispersion stabilizer prepared in advance and suspended using a high-speed disperser such as a high-speed stirrer or an ultrasonic disperser. And granulate.

  The polymerization initiator may be mixed with other additives when preparing the polymerizable monomer composition, or may be mixed into the polymerizable monomer composition just before being suspended in the aqueous medium. Good. Further, it may be added during granulation or after completion of granulation, that is, immediately before starting the polymerization reaction. Moreover, it can also add in the state melt | dissolved in the polymerizable monomer and other solvent as needed.

  In the polymerization reaction, the granulated suspension is heated to a temperature of 50 to 90 ° C., the particles of the polymerizable monomer composition in the suspension maintain the particle state, and the particles float and settle. To avoid this, it is carried out with stirring.

  The said polymerization initiator decomposes | disassembles easily by heating and produces | generates a free radical (radical). The generated radical is added to the unsaturated bond of the polymerizable monomer to newly generate an adduct radical. The generated adduct radical is further added to the unsaturated bond of the polymerizable monomer. By repeating such an addition reaction in a chain, the polymerization reaction proceeds, and core particles containing the polymerizable monomer as a main constituent material are formed.

  When the polymerization reaction is completed, the core particle dispersion is filtered by a known method, washed, and then dried or redispersed in water.

  Here, examples of the polymerizable monomer that can be used to obtain the binder resin that is the main constituent material of the core particles include the following.

  Styrene; α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-ethylstyrene, 2,4-dimethylstyrene, pn-butylstyrene, p-tert- Styrenes such as butyl styrene, pn-hexyl styrene, pn-octyl, pn-nonyl styrene, pn-decyl styrene, pn-dodecyl styrene, p-methoxy styrene, p-phenyl styrene Monomer: methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-propyl acrylate, n-octyl acrylate, dodecyl acrylate, 2-ethylhexyl acrylate, stearyl acrylate, acrylic acid 2-chloroethyl, phenyl acrylate, acrylic acid-2-hydro Acrylic esters such as ethyl; methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-octyl methacrylate, dodecyl methacrylate, 2-ethylhexyl methacrylate, methacrylic acid Methacrylic acid esters such as stearyl, phenyl methacrylate, 2-hydroxyethyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate; acrylonitrile, methacrylonitrile, acrylamide.

  Among these polymerizable monomers, it is preferable to use a mixture of styrene or a styrene derivative and another polymerizable monomer from the viewpoint of developing characteristics and durability of the toner. The mixing ratio of these polymerizable monomers may be appropriately selected in consideration of the desired glass transition temperature of the core particles.

  In the production of the core particles, a small amount of a polyfunctional monomer can be used in combination for the purpose of improving high temperature offset resistance. As the polyfunctional monomer, a compound having two or more polymerizable double bonds is mainly used. Aromatic divinyl compounds such as divinylbenzene and divinylnaphthalene; carboxylate esters having two double bonds such as ethylene glycol diacrylate, ethylene glycol dimethacrylate and 1,3-butanediol dimethacrylate; divinylaniline, divinyl ether and divinyl Divinyl compounds such as sulfide and divinyl sulfone; compounds having three or more vinyl groups.

  These polyfunctional monomers are not necessarily used, but the preferred addition amount when used is 0.01 to 1 part by mass with respect to 100 parts by mass of the monofunctional polymerizable monomer. .

  The polymerization initiator used in the production of the core particles is not particularly limited, and a known peroxide polymerization initiator or azo polymerization initiator can be used.

  Examples of peroxide polymerization initiators include the following. t-butyl peroxylaurate, t-butyl peroxyneodecanoate, t-butyl peroxypivalate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxyisobutyrate, t- Butyl peroxyacetate, t-butyl peroxyisononanoate, t-butyl peroxybenzoate, t-amyl peroxyneodecanoate, t-amyl peroxypivalate, t-amyl peroxy-2-ethylhexano Ate, t-amyl peroxyacetate, t-amyl peroxyisononanoate, t-amyl peroxybenzoate, t-hexyl peroxyneodecanoate, t-hexyl peroxypivalate, t-hexyl peroxy-2 -Ethyl hexanoate, t-hexyl peroxybenzoe Α-cumylperoxyneodecanoate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, 1,1,3,3-tetramethylbutylperoxyneodecanoate 1-cyclohexyl-1-methylethylperoxyneodecanoate, 2,5-dimethyl-2,5-bis (2-ethylhexanoylperoxy) hexane, 2,5-dimethyl-2,5-bis ( Peroxyester polymerization such as benzoylperoxy) hexane, t-butylperoxy-3,5,5-trimethylhexanoate, 2,5-dimethyl-2,5-bis (m-toluoylperoxy) hexane Initiator: di-n-propyl peroxydicarbonate, di-n-butyl peroxydicarbonate, di-n-pentylperoxydicarbonate Diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, di (2-ethoxyethyl) peroxydicarbonate, di (3-methoxybutyl) peroxydi Peroxydicarbonate-based polymerization initiators such as carbonate and di (4-t-butylcyclohexyl) peroxydicarbonate; diisobutyryl peroxide, diisononanoyl peroxide, di-n-octanoyl peroxide, dilauroylper Diacyl peroxide polymerization initiators such as oxide, distearoyl peroxide, dibenzoyl peroxide, di-m-toluoyl peroxide, benzoyl-m-toluoyl peroxide; t-hexyl peroxide Peroxymonocarbonate polymerization initiators such as pill monocarbonate, t-butylperoxyisopropyl monocarbonate, t-butylperoxy 2-ethylhexyl monocarbonate, t-butylperoxyallyl monocarbonate; 1,1-di-t -Hexylperoxycyclohexane, 1,1-di-t-butylperoxy-3,3,5-trimethylcyclohexane, 1,1-di-t-butylperoxycyclohexane, 2,2-di-t-butylper Peroxyketal polymerization initiators such as oxybutane; dialkyl peroxide polymerization initiators such as dicumyl peroxide, di-t-butyl peroxide, and t-butylcumyl peroxide.

  Examples of the azo polymerization initiator include the following. 2,2′-azobis- (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis -4-methoxy-2,4-dimethylvaleronitrile, azobisisobutyronitrile.

  Among these polymerization initiators, peroxide-based polymerization initiators are preferable because there is little residue of decomposition products. In addition, two or more of these polymerization initiators can be used simultaneously as necessary. In this case, the preferred amount of the polymerization initiator used is 0.1 to 20 parts by mass with respect to 100 parts by mass of the monomer.

  In the production of the core particles, a chain transfer agent can be used for the purpose of adjusting the molecular weight. Examples of the chain transfer agent include the following. n-pentyl mercaptan, isopentyl mercaptan, 2-methylbutyl mercaptan, n-hexyl mercaptan, n-heptyl mercaptan, n-octyl mercaptan, t-octyl mercaptan, t-nonyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, alkyl mercaptans such as n-tetradecyl mercaptan, t-tetradecyl mercaptan, n-pentadecyl mercaptan, n-hexadecyl mercaptan, t-hexadecyl mercaptan, stearyl mercaptan; alkyl esters of thioglycolic acid; mercaptopropionic acid Alkyl esters; halogenated hydrocarbons such as chloroform, carbon tetrachloride, ethylene bromide, carbon tetrabromide; α-methylstyrene dimer.

  These chain transfer agents are not necessarily used, but a preferable addition amount when used is 0.05 to 3 parts by mass with respect to 100 parts by mass of the polymerizable monomer.

  Moreover, in manufacture of the said core particle, you may superpose | polymerize by adding resin in a polymerizable monomer composition. For example, a polyester resin is a relatively polar resin containing many ester bonds. When this polyester resin is dissolved in the polymerizable monomer composition and polymerized, the resin tends to move to the surface layer of the droplets in the aqueous medium, and is unevenly distributed on the surface of the particle as the polymerization proceeds. Therefore, the granulation property is improved and the release agent can be easily included.

  The addition amount of the resin is preferably in the range of 1 to 20 parts by mass with respect to 100 parts by mass of the polymerizable monomer. If it is less than 1 part by mass, the effect of addition is small, and if it exceeds 20 parts by mass, it becomes difficult to design various physical properties of the toner.

  In the production of the core particles, as the dispersion stabilizer added to the aqueous medium, known surfactants, organic dispersants, and inorganic dispersants can be used. Among these, inorganic dispersants can be suitably used because they are less likely to produce ultrafine powder during polymerization, are less likely to lose stability even when the polymerization temperature is changed, are easily washed with acid, and do not adversely affect the toner. . Examples of such inorganic dispersants include the following. Polyvalent metal phosphates such as tricalcium phosphate, magnesium phosphate, aluminum phosphate and zinc phosphate; carbonates such as calcium carbonate and magnesium carbonate; inorganic salts such as calcium metasuccinate, calcium sulfate and barium sulfate; Inorganic oxides such as calcium hydroxide, magnesium hydroxide, aluminum hydroxide, silica, bentonite and alumina.

  When these inorganic dispersants are used, they may be used as they are in an aqueous medium, but in order to obtain finer particles, they are prepared and used in an aqueous medium using a compound capable of generating inorganic dispersant particles. You can also. For example, in the case of tricalcium phosphate, sodium phosphate aqueous solution and calcium chloride aqueous solution can be mixed under high-speed stirring to produce water-insoluble tricalcium phosphate, which enables more uniform and fine dispersion. Become. These inorganic dispersants can be almost completely removed by adding an acid or an alkali after the polymerization and dissolving.

  These inorganic dispersants are preferably used alone in an amount of 0.2 to 20 parts by mass with respect to 100 parts by mass of the polymerizable monomer, but if necessary, 0.001 to 0.1 parts by mass. These surfactants may be used in combination. Examples of the surfactant include the following. Sodium dodecylbenzene sulfate, sodium tetradecyl sulfate, sodium pentadecyl sulfate, sodium octyl sulfate, sodium oleate, sodium laurate, sodium stearate, potassium stearate.

  Moreover, the core particle in this invention can also be manufactured as follows by the dissolution suspension method.

  First, the binder resin as the main constituent material of the core particles is dissolved in an organic solvent in which the binder resin can be dissolved, and at least a colorant and a wax are added, and a homogenizer, a ball mill, a colloid mill, an ultrasonic disperser, etc. A binder resin composition in which these are uniformly dissolved or dispersed is prepared using a disperser.

  At this time, additives such as a charge control agent and a dispersant can be appropriately added to the binder resin composition as necessary.

  The amount of the binder resin dissolved in the organic solvent varies depending on the viscosity and solubility of the binder resin, but is preferably in the range of 40 to 60% by mass. The binder resin may be dissolved by heating at a temperature not higher than the boiling point of the organic solvent.

  Next, the binder resin composition is put into an aqueous medium containing a dispersion stabilizer prepared in advance and suspended using a high-speed disperser such as a high-speed shearing disperser or an ultrasonic disperser. , Granulate.

  At this time, the rotational speed is not particularly limited, but is usually 1000 to 30000 rpm, preferably 3000 to 20000 rpm. Further, the dispersion time is usually 0.1 to 5 minutes in the case of the batch method. The temperature during dispersion is usually 10 to 150 ° C., preferably 10 to 100 ° C.

  As the aqueous medium, water alone may be used, but a water-soluble solvent may be used in combination. Specific examples include alcohols such as methanol, isopropanol, and ethylene glycol, cellsolves such as dimethylformamide, tetrahydrofuran, and methyl cellosolve, and lower ketones such as acetone and methyl ethyl ketone. It is also a preferable method to mix an appropriate amount of the organic solvent used for preparing the binder resin composition. Thereby, the droplet during granulation can be maintained more stably.

  Next, the organic solvent is removed from the obtained droplets of the binder resin composition. As a specific method, a method of gradually raising the temperature of the entire system and evaporating the organic solvent in the droplets can be employed. In this way, core particles whose main constituent material is the binder resin are formed.

  The core particle dispersion is filtered by a known method, washed, and then dried or redispersed in water.

  Organic solvents that can dissolve the binder resin include hydrocarbon solvents such as ethyl acetate, xylene and hexane, halogenated hydrocarbon solvents such as methylene chloride, chloroform and dichloroethane, methyl acetate, ethyl acetate and butyl acetate. And ester solvents such as isopropyl acetate, ether solvents such as diethyl ether, and ketone solvents such as acetone, methyl ethyl ketone, diisobutyl ketone, cyclohexanone and methylcyclohexane.

  As the binder resin used for the production of the core particles, various resins conventionally known as toner binder resins are used. Among them, (a) a polyester resin, (b) a hybrid resin having a polyester resin unit and a vinyl resin unit, (c) a mixture of a polyester resin and a hybrid resin, (d) a mixture of a polyester resin and a vinyl resin, ( It is preferable that a main component is a resin selected from e) a mixture of a hybrid resin and a vinyl resin, and (f) a mixture of a polyester resin, a hybrid resin, and a vinyl resin.

  As the polyester resin, one obtained by polycondensation of a polyhydric alcohol component and a polycarboxylic acid component by a known method can be used. Specifically, the following compounds are mentioned.

  As the dihydric alcohol component, polyoxypropylene (2.2) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (3.3) -2,2-bis (4-hydroxyphenyl) propane , Polyoxyethylene (2.0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2.0) -polyoxyethylene (2.0) -2,2-bis (4-hydroxy) Phenyl) propane, polyoxypropylene (6) -2,2-bis (4-hydroxyphenyl) propane-like alkylene oxide adducts such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1 , 3-propylene glycol, 1,4-butanediol, neopentylglycol 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A, Examples thereof include hydrogenated bisphenol A, bisphenol derivatives represented by the following general formula (I), and compounds represented by the following general formula (II).

(In the formula, R is an ethylene or propylene group, x and y are each an integer of 1 or more, and the average value of x + y is 2 to 10.)

(In the formula, R ′ represents —CH ₂ CH ₂ —, —CH ₂ CH (CH ₃ ) —, or —CH ₂ —C (CH ₃ ) ₂ —).

  Examples of the trivalent or higher alcohol component include sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1 , 2,5-pentanetriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene. .

  As the polyvalent carboxylic acid component, aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid or anhydrides thereof; alkyl dicarboxylic acids such as oxalic acid, adipic acid, sebacic acid and azelaic acid or anhydrides thereof; Succinic acid substituted with 6 to 12 alkyl groups or anhydrides thereof; Unsaturated dicarboxylic acids such as fumaric acid, maleic acid and citraconic acid or anhydrides thereof; n-dodecenyl succinic acid, isododecenyl succinic acid, trimellit Examples include acids.

  Among these, in particular, a bisphenol derivative represented by the general formula (I) and an alkyl diol having 2 to 6 carbon atoms as a diol component, a carboxylic acid composed of a divalent carboxylic acid or an acid anhydride thereof, or a lower alkyl ester thereof. Acid components (for example, fumaric acid, maleic acid, maleic acid, phthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, alkyl dicarboxylic acids having 4 to 10 carbon atoms, and acid anhydrides of these compounds) as acid components Polyester resins obtained by condensation polymerization of these are preferred because they have good charging characteristics as color toners.

  Examples of the method for producing the polyester resin include a synthesis method by an oxidation reaction, a synthesis from a carboxylic acid and a derivative thereof, an ester group introduction reaction represented by a reaction with Michael, and a dehydration condensation reaction from a carboxylic acid compound and an alcohol compound. , A reaction from an acid halide and an alcohol compound, and a transesterification reaction. As the catalyst, a general acidic or alkaline catalyst used in the esterification reaction, for example, zinc acetate or a titanium compound can be used. Thereafter, it may be highly purified by a method such as a recrystallization method or a distillation method.

The hybrid resin can be produced by the following methods (1) to (4).
(1) A method of performing addition polymerization by forming a polyester resin unit and then adding a vinyl monomer in the presence of the unit.
(2) A method of performing polycondensation after forming a vinyl-based resin unit and adding a polyhydric alcohol and a polycarboxylic acid as raw materials for the polyester in the presence of the unit.
(3) A method of forming a polyester resin unit and a vinyl resin unit and then dissolving or swelling them in a small amount of an organic solvent, adding an esterification catalyst, and bonding them by heating.
(4) A method in which a monomer (polyhydric alcohol and polyvalent carboxylic acid) as a raw material for a polyester and a vinyl monomer are mixed and addition polymerization and polycondensation are continuously performed.

  In these production methods, the polyester resin unit and / or the vinyl resin unit preferably contain a monomer component capable of reacting with both unit components. Among the monomers constituting the polyester resin unit, those that can react with the vinyl resin unit include the following. Unsaturated dicarboxylic acids such as fumaric acid, maleic acid, citraconic acid and itaconic acid, or anhydrides thereof. Among the monomers constituting the vinyl resin unit, the following can be cited as those capable of reacting with the polyester resin unit. Monomers having a carboxyl group, monomers having a hydroxy group, acrylic esters, and methacrylic esters.

  In addition, in the production method of (1) above, a block type in which a vinyl resin unit is bonded by introducing a compound having a vinyl group separately at the end of the polyester resin unit and subjecting the vinyl monomer to addition polymerization. It is also possible to obtain a hybrid resin having Examples of such a compound having a vinyl group include acrylic acid esters and methacrylic acid esters having an isocyanate group.

  The vinyl monomer used for the production of the hybrid resin is not particularly limited, and the same monomer as the polymerizable monomer used as the main constituent material of the core particle by the suspension polymerization method described above. Can be used.

  In the production of the core particles, the dispersion stabilizer added to the aqueous medium may be the same as the dispersion stabilizer used for the production of the core particles by the suspension polymerization method described above.

  On the other hand, the resin fine particles used in the present invention may be produced by any method, and those produced by a known method such as an emulsion polymerization method, a soap-free emulsion polymerization method or a phase inversion emulsion method are used. be able to. Among these production methods, the phase inversion emulsification method is particularly suitable because it does not require an emulsifier or a dispersion stabilizer and resin particles having a smaller particle diameter can be easily obtained.

  In the phase inversion emulsification method, a resin having self-water dispersibility or a resin capable of expressing self-water dispersibility by neutralization is used. Here, the resin having self-water dispersibility is a resin containing a functional group capable of self-dispersion in an aqueous medium in the molecule, specifically, a carboxyl group, a sulfonic acid group, a phosphoric acid group or It is a resin containing these salts. Further, a resin that can exhibit self-water dispersibility by neutralization is a resin that contains functional groups in the molecule that can increase self-dispersibility in an aqueous medium by neutralization.

  When these self-water-dispersed resins are dissolved in an organic solvent, a neutralizing agent is added as necessary, and mixed with an aqueous medium while stirring, the resin solution causes phase inversion emulsification to form fine particles. Generate. The organic solvent is removed using a method such as heating and decompression after phase inversion emulsification.

  Thus, according to the phase inversion emulsification method, a stable aqueous dispersion of resin fine particles can be obtained without substantially using an emulsifier or a dispersion stabilizer due to the action of the functional group.

  The resin fine particles obtained in this manner can be directly used as an aqueous dispersion for the fixing step to the core particles. Further, an acid may be added to the aqueous dispersion to return the acidic group in the resin from the salt state to the acid state, and after filtration and washing, the acid group may be redispersed in water.

  The resin material may be any material that can be used as a binder resin for toner, and vinyl resin, polyester resin, epoxy resin, and urethane resin are used.

  The organic solvent is not particularly limited as long as it dissolves the resin, but it is more preferable to use a low boiling point solvent that can be easily removed.

  A preferable average particle diameter of the resin fine particles is a median diameter value determined by particle size distribution measurement by a laser scattering method, and is in the range of 10 to 100 nm. When the median particle size is less than 10 nm, it is difficult to form an outer shell having a sufficient thickness, and when it exceeds 100 nm, it is difficult to form an outer shell having a uniform thickness. On the contrary, if the particle diameter is within the above range, a toner having sufficient heat-resistant storage stability can be obtained.

  The median diameter is a particle diameter defined as a 50% value (central cumulative value) of a cumulative curve of particle size distribution. For example, a laser diffraction / scattering particle size distribution measuring apparatus (LA-) manufactured by HORIBA, Ltd. 920).

  When the resin fine particles are attached to the surface of the core particle, it is usually performed in a state where they are dispersed in an aqueous medium. When the polarities of the core particles and the resin fine particles are greatly different, they can be attached by an electric suction force. Otherwise, it is necessary to control the dispersion state of the resin fine particles using an external means. . As a specific method, in addition to the method of adjusting the pH of the aqueous medium described above, a method of adding an inorganic salt to the aqueous medium can be mentioned. In either case, if the dispersion state of the resin fine particles is suddenly changed, the resin fine particles cause single aggregation and cannot be uniformly adhered, so that these operations are preferably performed gradually.

  In addition, after the resin fine particles are adhered, they are fixed so as not to easily peel off or drop off. As a specific method, a method of heat-treating in a state dispersed in an aqueous medium, a method of adding a solvent that dissolves or swells resin fine particles to absorb and forming a film, removing the solvent, filtration and A method of stirring and mixing the powder taken out after drying is heated. Among these methods, the heat treatment method in an aqueous medium is preferable in that it can be fixed more uniformly and firmly and the operation is simple. However, if the amount of resin fine particles to be attached is small or the resin fine particles do not have a sufficiently high glass transition temperature with respect to the core particles, the core particles may be fused together. is necessary.

  A particularly preferred example will be described in detail as a method for attaching and fixing the resin fine particles to achieve the present invention.

  First, core particles are produced according to the suspension polymerization method or dissolution suspension method described above. At this time, as the dispersion stabilizer, for example, an inorganic dispersant having a significantly different polarity with respect to the core particles such as tricalcium phosphate is used, and the dispersion stabilizer attached to the surface is not removed even after the core particles are produced. Continue stirring.

  Next, an aqueous dispersion of resin fine particles composed of a resin having at least a sulfonic acid group and a carboxylic acid group and having a glass transition temperature higher than that of the core particle in the core particle dispersion with the dispersion stabilizer attached. Add body. At this time, since the resin fine particles have the same polarity with respect to the dispersion stabilizer as the core particles, they uniformly adhere to the surface of the core particles with the dispersion stabilizer interposed.

  Next, while stirring this dispersion, the dispersion is heated to a temperature range of not less than the glass transition temperature of the core particles and not more than the temperature obtained by subtracting 5 ° C. from the glass transition temperature of the resin fine particles.

  Then, while keeping the temperature of the dispersion within the above temperature range, acid is slowly added thereto, and the dispersion is adjusted so that the pH of the dispersion is less than pH (c) at which the dispersion stabilizer dissolves, and further stirred. to continue. In order to dissolve the dispersion stabilizer with certainty, it is preferable that the pH of the dispersion is not more than pH obtained by subtracting 0.5 from pH (c).

  In this way, when the dispersion stabilizer is gradually dissolved and the dispersion stabilizer is removed, the resin fine particles are simultaneously brought into contact with the surface of the core particle and fixed while maintaining a uniform state.

  In this way, it is possible to obtain a toner having a capsule structure that is a thin layer but has a coating layer that is homogeneous and excellent in mechanical strength.

  In the present invention, the coating layer formed of resin fine particles preferably covers 90% or more of the surface of the core particles, and particularly preferably 100%. A suitable use amount of the resin fine particles for satisfying such a coverage is not uniquely determined, and may be appropriately adjusted according to the particle diameters of the core particles and the resin fine particles. Further, the resin fine particles to be fixed do not necessarily have to be a single layer, and may be a multilayer in order to cover 100%.

  The coverage can also be obtained directly from an observation image of each toner cross section by a transmission electron microscope (TEM). However, an element inherent to the resin constituting the resin fine particles (for example, S derived from a sulfonic acid group). In the case of containing an element), the element can be quantitatively analyzed using a fluorescent X-ray analyzer (XRF), for example, and calculated.

  As the colorant used in the toner of the present invention, known ones can be used, and examples thereof include carbon black as a black colorant, magnetic powder, and yellow / magenta / cyan colorants shown below.

  Examples of the yellow colorant include the following. Condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, allylamide compounds. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 109, 110, 111, 128, 129, 147, 168, 180 are preferably used.

  Examples of the magenta colorant include the following. Condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinones, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, perylene compounds. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81: 1, 122, 144, 146, 166, 169, 177, 184, 185, 202, 206, 220, 221, and 254 are preferably used.

  Examples of the cyan colorant include the following. Copper phthalocyanine compounds and derivatives thereof, anthraquinone compounds, basic dye lake compounds. Specifically, C.I. I. Pigment Blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, 66 are preferably used.

  These colorants can be used alone or in combination, and further in the form of a solid solution. When magnetic powder is used as the black colorant, the amount added is preferably 40 to 150 parts by mass with respect to 100 parts by mass of the binder resin in the core particles. When carbon black is used as the black colorant, the amount added is preferably 1 to 20 parts by mass with respect to 100 parts by mass of the binder resin in the core particles. Further, in the case of a color toner, it is selected from the viewpoints of hue angle, saturation, lightness, weather resistance, OHP transparency, and dispersibility in the toner, and the preferred addition amount is 100 parts by mass of the binder resin in the core particles. 1 to 20 parts by mass with respect to.

  These colorants need to pay attention to polymerization inhibition and aqueous phase migration, and are preferably subjected to surface modification such as a hydrophobization treatment as necessary. For example, a preferable method for surface-treating a dye-based colorant includes a method in which a polymerizable monomer is polymerized in the presence of a dye in advance, and the obtained colored polymer is added to the monomer composition. . For carbon black, in addition to the same treatment as the above dye, a grafting treatment may be performed with a substance that reacts with the surface functional group of carbon black, for example, polyorganosiloxane.

  The magnetic powder is mainly composed of iron oxide such as triiron tetroxide and γ-iron oxide, and generally has hydrophilicity. Therefore, the magnetic powder is likely to be unevenly distributed on the particle surface due to the interaction with water as a dispersion medium, and the resulting toner particles are inferior in fluidity and frictional charging uniformity due to the magnetic powder exposed on the surface. Become. Therefore, the surface of the magnetic powder is preferably subjected to a hydrophobic treatment uniformly with a coupling agent. Examples of the coupling agent that can be used include a silane coupling agent and a titanium coupling agent, and a silane coupling agent is particularly preferably used.

  The toner of the present invention contains a wax for improving fixability. Usable waxes include the following. Petroleum wax such as paraffin wax, microcrystalline wax, petrolatum and derivatives thereof; montan wax and derivatives thereof; hydrocarbon wax and derivatives thereof according to Fischer-Tropsch method; polyolefin wax and derivatives thereof represented by polyethylene; carnauba wax and candelilla Natural waxes such as waxes and derivatives thereof. Derivatives include block copolymers with oxides and vinyl monomers, and graft modified products. Furthermore, higher fatty alcohols, fatty acids such as stearic acid and palmitic acid, or compounds thereof, acid amide waxes, ester waxes, ketones, hydrogenated castor oil and derivatives thereof, plant-based waxes and animal waxes can also be used. These waxes may be used alone or in combination of two or more.

  Among these waxes, those having a maximum endothermic peak temperature in the region of 40 to 130 ° C. at the time of temperature rise in the DSC curve measured by a differential scanning calorimeter are preferable, and further the maximum endothermic peak temperature in the region of 45 to 120 ° C. It is more preferable to have By using such a wax, the releasability can be effectively expressed while greatly contributing to the low-temperature fixability. When the maximum endothermic peak temperature is less than 40 ° C., the self-cohesive force of the wax component becomes weak, and as a result, the high temperature offset resistance is lowered. Further, exudation of wax is likely to occur at times other than during fixing, and the triboelectric charge amount of the toner is reduced, and the durability under high temperature and high humidity is reduced. On the other hand, if the maximum endothermic peak temperature exceeds 130 ° C., the fixing temperature becomes high and low temperature offset tends to occur, which is not preferable. Furthermore, if the maximum endothermic peak temperature is too high, the wax component precipitates during the granulation, and the dispersibility of the wax decreases, which is not preferable.

  The content of the wax is preferably 1 to 30 parts by mass and more preferably 3 to 20 parts by mass with respect to 100 parts by mass of the binder resin. When the content of the wax is less than 1 part by mass, a sufficient addition effect cannot be obtained, and the offset suppression effect also decreases. On the other hand, when it exceeds 30 parts by mass, the long-term storage stability is deteriorated and the dispersibility of other toner materials such as a colorant is deteriorated, so that the fluidity of the toner and the image characteristics are liable to be deteriorated. Further, the wax component oozes out at the time of fixing, and the durability under high temperature and high humidity is lowered.

  The toner of the present invention may contain a charge control agent as necessary for the purpose of stabilizing the charge characteristics. As a method of inclusion, there are a method of adding to the inside of toner particles and a method of adding externally. As the charge control agent, a known one can be used, but when added inside, a charge control agent having a low polymerization inhibitory property and substantially free from a solubilized product in an aqueous dispersion medium is particularly preferable. Specific examples of the negative charge control agent include the following compounds. Metallic compounds of aromatic carboxylic acids such as salicylic acid, alkylsalicylic acid, dialkylsalicylic acid, naphthoic acid, dicarboxylic acid; metal salts or metal complexes of azo dyes or azo pigments; polymer type having sulfonic acid or carboxylic acid group in the side chain Compound: Boron compound, urea compound, silicon compound, calixarene. Examples of positive charge control agents include quaternary ammonium salts, polymer compounds having quaternary ammonium salts in the side chain, guanidine compounds, nigrosine compounds, and imidazole compounds.

  The amount of these charge control agents to be used is determined by the toner production method including the type of binder resin, the presence or absence of other additives, and a dispersion method, and is not uniquely limited. When added internally, it is preferably used in the range of 0.1 to 10 parts by mass, more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the binder resin. In the case of external addition, the amount is preferably 0.005 to 1.0 part by mass, more preferably 0.01 to 0.3 part by mass with respect to 100 parts by mass of the toner particles.

  The toner obtained according to the present invention has a weight average particle diameter (D4) of 3.0 to 10.0 μm in order to faithfully develop finer electrostatic latent image dots and obtain a high-quality image. preferable. When the weight average particle diameter is less than 3.0 μm, the transfer residual toner on the photoconductor increases due to a decrease in transfer efficiency, and it becomes difficult to suppress the photoconductor scraping and toner fusion in the contact charging step. In addition to increasing the surface area of the entire toner, the fluidity and agitation of the powder are reduced, making it difficult to triboelectrically charge individual toner particles, resulting in ghosting, fogging, and transferability. Tends to decrease. On the other hand, if the weight average particle diameter exceeds 10.0 μm, the characters and line images are likely to be scattered and it becomes difficult to obtain high resolution. Also, as the device becomes higher in resolution, the reproducibility of one dot tends to deteriorate.

  Here, the average particle size and particle size distribution of the toner can be measured using a Coulter Counter TA-II type or Coulter Multisizer (both manufactured by Coulter). In the present invention, a Coulter multisizer was used, and an interface (manufactured by Nikka Machine Co., Ltd.) for outputting the number distribution and the volume distribution and a PC9801 personal computer (manufactured by NEC Corporation) were connected thereto. As the electrolytic solution, a 1% NaCl aqueous solution prepared using primary sodium chloride was used.

  As a measurement method, 0.1 to 5 ml of a surfactant, preferably alkylbenzene sulfonate, is added as a dispersant to 100 to 150 ml of the electrolytic solution, and 2 to 20 mg of a measurement sample is further added. Next, the electrolytic solution is subjected to a dispersion treatment with an ultrasonic disperser for about 1 to 3 minutes, and the volume and number of particles having a size of 2 μm or more are measured by the Coulter Multisizer using a 100 μm aperture as an aperture. Calculate the distribution. Then, a weight average particle diameter (D4) and a number average particle diameter (D1) are obtained.

  The average circularity of the toner obtained by the present invention is preferably 0.970 or more. The average circularity is an index representing the degree of unevenness of toner particles, and is 1.000 when the toner is a perfect sphere, and the value becomes smaller as the shape becomes more complicated. That is, that the average circularity is 0.970 or more means that the toner shape is substantially spherical. The toner having such a shape is likely to have uniform frictional charging and is effective in suppressing fogging and sleeve ghosting. Further, since the toner ears formed on the toner carrier are uniform, control in the developing unit is facilitated. Furthermore, since it has a spherical shape, it has good fluidity and is not easily stressed in the developing device, so that the chargeability is not easily lowered even when used for a long time under high humidity. Further, since heat and pressure are easily applied to the entire toner even at the time of fixing, it contributes to improvement of fixing properties.

  The average circularity in the present invention was measured using a flow type particle image analyzer (FPIA-3000 type) manufactured by Sysmex Corporation.

  As a specific measurement method, an appropriate amount of a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant to 20 ml of ion-exchanged water, and then 0.02 g of a measurement sample is added. Then, a dispersion process for 2 minutes is performed using a tabletop ultrasonic cleaner / disperser (eg, VS-150 manufactured by Vervo Creer) having an oscillation frequency of 50 kHz and an electric output of 150 W, To do. In that case, it cools suitably so that the temperature of a dispersion liquid may become 10 to 40 degreeC.

  For the measurement, the flow type particle image measuring apparatus equipped with a standard objective lens (10 times) is used, and a particle sheath (PSE-900A) manufactured by Sysmex Corporation is used as the sheath liquid. The dispersion liquid prepared according to the above procedure is introduced into the flow type particle image measuring apparatus, 3000 toner particles are measured in the total count mode, and the analysis particle diameter is limited to a circle equivalent diameter of 3.00 μm to 200.00 μm. The average circularity of the toner particles is obtained.

  In measurement, automatic focus adjustment is performed using standard latex particles (for example, a product obtained by diluting 5200A manufactured by Duke Scientific with ion-exchanged water) before the measurement is started. Thereafter, it is preferable to perform focus adjustment every two hours from the start of measurement.

  In the examples, a flow-type particle image measuring apparatus that has been calibrated by Sysmex Corporation and that has been issued a calibration certificate issued by Sysmex Corporation was used. Measurement was performed under the measurement and analysis conditions when the calibration certificate was received, except that the analysis particle diameter was limited to a circle equivalent diameter of 3.00 μm or more and 200.00 μm or less.

  The toner of the present invention is preferably externally added with a fluidity improver to improve image quality. As the fluidity improver, inorganic fine powders such as silica, titanium oxide, and aluminum oxide are preferably used. These inorganic fine powders are preferably hydrophobized with a silane coupling agent, silicone oil, or both.

  The toner of the present invention can be used as it is as a one-component developer or as a two-component developer by mixing with a magnetic carrier. When used as a two-component developer, the 50% particle size (D50) of the carrier to be mixed is preferably 10 to 100 μm, and the toner concentration in the two-component developer is preferably 2 to 15% by mass. .

  Hereinafter, the production method of the present invention will be specifically described with reference to examples.

<Synthesis Example 1: Resin fine particle dispersion (a)>
(Production of polyester resin)
The following monomers were charged into a reaction vessel equipped with a stirrer, condenser, thermometer and nitrogen introduction tube, 0.03 parts by mass of tetrabutoxy titanate was added as an esterification catalyst, and the temperature was raised to 220 ° C. in a nitrogen atmosphere. Warmed and reacted for 5 hours with stirring.
Bisphenol A-propylene oxide 2-mol adduct: 49.2 parts by mass Ethylene glycol: 9.0 parts by mass Terephthalic acid: 22.0 parts by mass Isophthalic acid: 12.6 parts by mass 5-sodium sulfoisophthalic acid: 3.8 parts by mass Then, 3.4 parts by mass of trimellitic anhydride was added, and the reaction was further carried out for 5 hours while reducing the pressure in the reaction vessel to 5 to 20 mmHg to obtain a polyester resin.

(Preparation of resin fine particle dispersion)
A reaction vessel equipped with a stirrer, a condenser, a thermometer, and a nitrogen introduction tube was charged with 100.0 parts by mass of the obtained polyester resin and 75.0 parts by mass of butyl cellosolve, heated to 90 ° C. and dissolved, then 70 Cooled to ° C.

  Next, 18.0 parts by mass of a 1 mol / liter aqueous ammonia solution was added, and the mixture was stirred for 30 minutes while maintaining the above temperature. Then, 300.0 parts by mass of ion-exchanged water having a temperature of 70 ° C. was added and dispersed in water. It was. The obtained aqueous dispersion was transferred to a distillation apparatus and distilled until the fraction temperature reached 100 ° C.

  After cooling, ion-exchanged water was added to the obtained aqueous dispersion to adjust the resin concentration in the dispersion to 20%. The obtained dispersion was cloudy and no precipitation was observed. This was designated as resin fine particle dispersion (a).

<Synthesis Example 2: Resin fine particle dispersion (b)>
(Production of polyester resin)
In Synthesis Example 1, an aqueous polyester resin dispersion was obtained in the same manner as in Synthesis Example 1 except that the amount of monomer charged was changed as follows. The obtained dispersion was cloudy and no precipitation was observed. This was designated as resin fine particle dispersion (b).
Bisphenol A-propylene oxide 2-mol adduct: 49.4 parts by mass Ethylene glycol: 9.1 parts by mass Terephthalic acid: 22.2 parts by mass Isophthalic acid: 12.8 parts by mass 5-sodium sulfoisophthalic acid: 1.4 parts by mass Parts Trimellitic anhydride: 5.1 parts by mass

<Synthesis Example 3: Resin fine particle dispersion (c)>
In Synthesis Example 1, an aqueous polyester resin dispersion was obtained in the same manner as in Synthesis Example 1 except that the amount of monomer charged was changed as follows. The obtained dispersion was cloudy and no precipitation was observed. This was designated as resin fine particle dispersion (c).
Bisphenol A-propylene oxide 2-mol adduct: 49.5 parts by mass Ethylene glycol: 9.2 parts by mass Terephthalic acid: 22.2 parts by mass Isophthalic acid: 12.8 parts by mass 5-sodium sulfoisophthalic acid: 0.5 mass Parts Trimellitic anhydride: 5.8 parts by mass

<Synthesis Example 4: Resin fine particle dispersion (d)>
In Synthesis Example 1, an aqueous polyester resin dispersion was obtained in the same manner as in Synthesis Example 1 except that the amount of monomer charged was changed as follows. The obtained dispersion was cloudy and no precipitation was observed. This was designated as resin fine particle dispersion (d).
Bisphenol A-propylene oxide 2 mol adduct: 49.0 parts by mass Ethylene glycol: 8.7 parts by mass Terephthalic acid: 20.2 parts by mass Isophthalic acid: 10.6 parts by mass 5-sodium sulfoisophthalic acid: 6.7 parts by mass Parts Trimellitic anhydride: 4.8 parts by mass

<Synthesis Example 5: Resin fine particle dispersion (e)>
(Production of polyester resin)
The following monomers were charged into a reaction vessel equipped with a stirrer, condenser, thermometer and nitrogen introduction tube, 0.03 parts by mass of tetrabutoxy titanate was added as an esterification catalyst, and the temperature was raised to 220 ° C. in a nitrogen atmosphere. Warmed and reacted for 5 hours with stirring.
Bisphenol A-propylene oxide 2 mol adduct: 49.0 parts by mass Ethylene glycol: 8.6 parts by mass Terephthalic acid: 21.8 parts by mass Isophthalic acid: 12.0 parts by mass 5-sodium sulfoisophthalic acid: 8.6 parts by mass Part Next, the reaction vessel was further reacted for 5 hours while reducing the pressure in the reaction vessel to 5 to 20 mmHg to obtain a polyester resin.

(Preparation of resin fine particle dispersion)
A reaction vessel equipped with a stirrer, a condenser, a thermometer, and a nitrogen introduction tube was charged with 100.0 parts by mass of the obtained polyester resin, 45.0 parts by mass of methyl ethyl ketone, and 45.0 parts by mass of tetrahydrofuran, and heated to a temperature of 80 ° C. And dissolved.

  Next, after stirring, 300.0 parts by mass of ion-exchanged water having a temperature of 80 ° C. is added and dispersed in water, and the resulting aqueous dispersion is transferred to a distillation apparatus and distilled until the fraction temperature reaches 100 ° C. went.

  After cooling, ion-exchanged water was added to the obtained aqueous dispersion to adjust the resin concentration in the dispersion to 20%. The obtained dispersion was cloudy and no precipitation was observed. This was designated as resin fine particle dispersion (e).

<Synthesis Example 6: Resin fine particle dispersion (f)>
In Synthesis Example 1, an aqueous dispersion of a polyester resin was obtained in the same manner as in Synthesis Example 1, except that the monomer charge was changed as follows. This was designated as resin fine particle dispersion (f).
Bisphenol A-propylene oxide 2 mol adduct: 49.5 parts by mass Ethylene glycol: 9.2 parts by mass Terephthalic acid: 23.5 parts by mass Isophthalic acid: 14.3 parts by mass 5-sodium sulfoisophthalic acid: 1.5 parts by mass Parts Trimellitic anhydride: 2.0 parts by mass

<Synthesis Example 7: resin fine particle dispersion (g)>
In Synthesis Example 1, an aqueous dispersion of a polyester resin was obtained in the same manner as in Synthesis Example 1, except that the monomer charge was changed as follows. The obtained dispersion was cloudy and no precipitation was observed. This was designated as resin fine particle dispersion (g).
Bisphenol A-propylene oxide 2 mol adduct: 49.5 parts by mass Ethylene glycol: 9.2 parts by mass Terephthalic acid: 23.0 parts by mass Isophthalic acid: 12.1 parts by mass Trimellitic anhydride: 6.2 parts by mass With respect to the obtained resin fine particle dispersions (a) to (g), the median diameter of the resin fine particles in each dispersion was measured using a laser diffraction / scattering particle size distribution measuring apparatus LA-920 (manufactured by Horiba, Ltd.). It was measured.

  Further, the zeta potential of each resin fine particle is measured using an ultrasonic zeta potential measuring device DT-1200 (manufactured by Dispersion Technology), and the pH (a) value indicating the isoelectric point is obtained according to the above-described method. It was.

  Moreover, after extracting a part of each dispersion liquid, filtering and washing | cleaning, drying and taking out as solid content, the acid value and glass transition temperature of the resin which were obtained were measured, respectively. The carboxylic acid value was determined by the above-described titration method, and the sulfonic acid value was determined by calculation from the quantitative result of S element by a fluorescent X-ray analyzer (XRF).

  The results are summarized in Table 1 respectively.

<Synthesis Example 8: Core particle dispersion (A)>
(Preparation of pigment dispersion paste)
Styrene: 212.9 parts by mass Cu phthalocyanine (CI Pigment Blue 15: 3): 19.7 parts by mass After sufficiently premixing the above materials in a container, an attritor (with a temperature of 20 ° C. or less) Using a Mitsui Miike Chemical Industries Co., Ltd.), the mixture was uniformly dispersed and mixed for about 4 hours to prepare a pigment dispersion paste.

(Preparation of core particle dispersion)
Into 1152.0 parts by mass of ion-exchanged water, 390.0 parts by mass of a 0.1 mol / liter-sodium phosphate (Na ₃ PO ₄ ) aqueous solution was added and stirred using CLEARMIX (M Technique Co., Ltd.). , Heated to 60 ° C. To this, 58.0 parts by mass of 1.0 mol / liter-calcium chloride (CaCl ₂ ) aqueous solution was added and stirring was continued, and a dispersion stabilizer composed of tricalcium phosphate (Ca ₃ (PO ₄ ) ₂ ) was added. An aqueous medium containing was prepared.

  Part of the obtained aqueous medium is withdrawn, and a 0.1 mol / liter hydrochloric acid aqueous solution is slowly dropped while stirring, and the dropping is continued until the cloudiness of the tricalcium phosphate colloid disappears by visual observation. The change in pH was measured. Thus, a hydrochloric acid dropping amount-pH curve was prepared, and the pH (c) when tricalcium phosphate was completely dissolved was determined from the inflection point of the graph.

On the other hand, the following materials were added to the pigment dispersion paste and dispersed and mixed using an attritor (manufactured by Mitsui Miike Chemical Industries) to prepare a polymerizable monomer composition.
n-butyl acrylate: 114.7 parts by mass Saturated polyester resin (terephthalic acid-propylene oxide modified bisphenol A polycondensate, weight average molecular weight (Mw): 20,000, Tg: 60 ° C., acid value: 10 mgKOH / g): 20 0.0 part by mass The above polymerizable monomer composition is heated to 60 ° C., and ester wax (main component C ₁₉ H ₂₉ COOC ₂₀ H ₄₁ , DSC maximum endothermic peak temperature 68.6 ° C.) is 32.7 parts by mass. Part was added and mixed and dissolved.

  Next, 9.8 parts by mass of 2,2'-azobis (2,4-dimethylvaleronitrile) was further added and dissolved as a polymerization initiator.

  This was put into the aqueous medium, and granulated by stirring for 15 minutes at a rotation speed of 12,000 rpm under a nitrogen atmosphere at a temperature of 60 ° C. using CLEARMIX (M Technique Co., Ltd.).

  Furthermore, the obtained suspension was polymerized at a temperature of 60 ° C. for 10 hours while stirring with a paddle stirring blade.

  After completion of the polymerization, the obtained dispersion of polymer particles was cooled, and ion exchange water was added to adjust the concentration of the polymer particles in the dispersion to 20% by mass. This was designated as core particle dispersion (A).

  A part of the obtained core particle dispersion (A) was extracted, and after adding hydrochloric acid to remove the dispersion stabilizer, filtration, washing and drying were performed.

The core particles (A) thus obtained were measured for average particle diameter and average circularity, glass transition temperature, and BET specific surface area. As a result, the weight average particle diameter (D4) was 6.4 μm, the number average particle diameter (D1) was 5.5 μm, the average circularity was 0.978, the glass transition temperature was 45 ° C., and the BET specific surface area was 1.04 m ^2. / G. Further, the value of isoelectric point pH (b) was determined by measuring the zeta potential and found to be 2.15.

<Synthesis Example 9: Core particle dispersion (B)>
(Production of polyester resin)
The following monomers and condensation catalyst were charged into a reaction vessel equipped with a stirrer, a condenser, a thermometer, and a nitrogen introduction tube.
1,3-propanediol: 847 parts by mass Terephthalic acid dimethyl ester: 861 parts by mass 1,6-hexanedioic acid: 212 parts by mass Tetrabutoxy titanate (catalyst): 3 parts by mass The temperature in the reaction vessel is 170 ° C. in a nitrogen atmosphere. The reaction was carried out for 7 hours while stirring and distilling off the methanol produced.

  Next, the temperature was gradually raised to 240 ° C., the reaction was carried out for 5 hours while distilling off the produced propylene glycol and water, and the reaction was further carried out under a reduced pressure of 20 mmHg.

  The produced solid content was taken out, cooled to room temperature, pulverized and granulated to obtain a polyester resin. The glass transition temperature of the obtained polyester resin was 44 ° C.

(Preparation of binder resin solution)
50 parts by mass of ethyl acetate was put into a sealed container equipped with stirring blades, 50 parts by mass of the polyester resin was added to the stirring at a rotation speed of 100 rpm, and the binder resin solution was prepared by stirring at room temperature for 3 days. .

(Preparation of wax dispersion)
82 parts by mass of ethyl acetate and 18 parts by mass of carnauba wax (DSC maximum endothermic peak temperature 83 ° C.) are charged into a vessel equipped with stirring blades, and the carnauba wax is dissolved in ethyl acetate by heating the inside to a temperature of 70 ° C. I let you.

  Subsequently, it cooled to the temperature of 30 degreeC over 2 hours, stirring gently at the rotation speed of 100 rpm, and the milky white liquid was obtained.

  Furthermore, this solution was put into a heat-resistant container together with 20 parts by weight of 1 mm glass beads, dispersed for 3 hours with a paint shaker, and then the glass beads were removed with a nylon mesh to obtain a wax dispersion.

(Preparation of colorant dispersion)
Polyester resin: 20 parts by mass Cu phthalocyanine (CI Pigment Blue 15: 3): 20 parts by mass Ethyl acetate: 60 parts by mass After sufficiently premixing the above materials in a container, the temperature is kept at 20 ° C. or lower. The mixture was uniformly dispersed and mixed for about 4 hours using an attritor (manufactured by Mitsui Miike Chemical Industries) to obtain a colorant dispersion.

(Preparation of oil phase)
Wax dispersion (wax solid content: 18% by mass): 50 parts by mass Colorant dispersion (pigment solid content: 20% by mass, resin solid content: 20% by mass): 25 parts by mass Binder resin solution (resin solid content: 50 parts by mass): 160 parts by mass Ethyl acetate: 15 parts by mass The above materials are put into a container, and stirred and dispersed for 5 minutes at a rotation speed of 2000 rpm using a homodisper (manufactured by Tokushu Kika Kogyo Co., Ltd.). To prepare an oil phase.

(Preparation of aqueous phase)
Into 1152.0 parts by mass of ion-exchanged water, 390.0 parts by mass of a 0.1 mol / liter-sodium phosphate (Na ₃ PO ₄ ) aqueous solution was added and stirred using CLEARMIX (M Technique Co., Ltd.). , Heated to 60 ° C. To this, 58.0 parts by mass of 1.0 mol / liter-calcium chloride (CaCl ₂ ) aqueous solution was added and stirring was continued, and a dispersion stabilizer composed of tricalcium phosphate (Ca ₃ (PO ₄ ) ₂ ) was added. An aqueous medium was prepared, and 100 parts by mass of ethyl acetate was further mixed to prepare an aqueous phase.

(Preparation of core particle dispersion)
The oil phase is charged into the aqueous phase, and granulation is performed using Claremix (M Technique Co., Ltd.) under a nitrogen atmosphere at a temperature of 60 ° C. and stirring at a rotation speed of 10,000 rpm for 1 minute. It was.

  Further, the obtained suspension was stirred for 5 hours with stirring at a paddle stirring blade at a temperature of 60 ° C. and a reduced pressure of 500 mgHg.

  The dispersion thus obtained was cooled, and ion exchange water was added to adjust the particle concentration in the dispersion to 20% by mass. This was used as a core particle dispersion (B).

  A part of the obtained core particle dispersion (B) was extracted, and hydrochloric acid was added to remove the dispersion stabilizer, followed by filtration, washing with water and drying.

The core particles (B) thus obtained were measured for average particle diameter and average circularity, glass transition temperature, and BET specific surface area. As a result, the weight average particle diameter (D4) was 6.6 μm, the number average particle diameter (D1) was 5.3 μm, the average circularity was 0.970, the glass transition temperature was 45 ° C., and the BET specific surface area was 1.15 m ^2. / G. In addition, the zeta potential was measured and the value of isoelectric point pH (b) was determined to be 2.12.

<Synthesis Example 10: Core particle dispersion (C)>
In Synthesis Example 8, after the polymerization was completed, the obtained dispersion of polymer particles was cooled, and a 1 mol / liter hydrochloric acid aqueous solution was added to dissolve the dispersion stabilizer, followed by filtration, washing with water and core particles (C )

A part of the obtained core particles (C) was dried, and the average particle diameter and average circularity, glass transition temperature, and BET specific surface area were measured. As a result, the weight average particle diameter (D4) was 6.4 μm, the number average particle diameter (D1) was 5.5 μm, the average circularity was 0.978, the glass transition temperature was 45 ° C., and the BET specific surface area was 1.04 m ^2. / G. Further, the value of isoelectric point pH (b) was determined by measuring the zeta potential and found to be 2.15.

  Ion exchange water was added to the core particles (C) and reslurried to adjust the polymer particle concentration in the dispersion to 20% by mass. This was designated as core particle dispersion (C).

<Example 1>
(Production of toner particles)
The fine resin particle dispersion (a) 25.0 obtained in Synthesis Example 1 is stirred with 500.0 parts by mass (solid content 100.0 parts by mass) of the core particle dispersion (A) obtained in Synthesis Example 8. After adding mass part (solid content 5.0 mass part) and continuing stirring for 30 minutes, it heated up at the temperature of 60 degreeC.

  Next, a 0.2 mol / liter hydrochloric acid aqueous solution was added dropwise at a dropping rate of 0.005 liter / min until the pH of the dispersion reached 1.50. Stirring was continued for 3 hours while maintaining the above temperature, and the resin fine particles were fixed to the surface of the core particles, then cooled, filtered, washed with water and dried to obtain toner particles.

(Production of toner)
100 parts by weight of silica fine powder is treated with 10 parts by weight of hexamethyldisilazane, and further treated with 10 parts by weight of silicone oil to give a hydrophobic number average primary particle size of 12 nm and a BET specific surface area of 120 m ² / g. Silica fine powder was prepared. Next, 1.0 part by mass of the hydrophobic silica fine powder was added to 100.0 parts by mass of the toner particles, and mixed using a Henschel mixer (manufactured by Mitsui Miike Chemical Industries). Thus, the toner of the present invention was produced.

<Example 2>
A toner of the present invention was produced in the same manner as in Example 1 except that a 0.2 mol / liter hydrochloric acid aqueous solution was dropped until the pH of the dispersion became 2.00.

<Comparative Example 1>
A toner of Comparative Example was prepared in the same manner as in Example 1 except that a 0.2 mol / liter hydrochloric acid aqueous solution was dropped until the pH of the dispersion became 1.20.

<Comparative example 2>
A toner of Comparative Example was prepared in the same manner as in Example 1 except that a 0.2 mol / liter hydrochloric acid aqueous solution was dropped until the pH of the dispersion became 2.50.

<Examples 3 to 7>
In Example 1, the toner of the present invention was prepared in the same manner as in Example 1 except that the resin fine particle dispersions (b) to (f) were used in place of the fine particle dispersion (a).

<Example 8>
A toner of the present invention was produced in the same manner as in Example 1 except that instead of the core particle dispersion (A), the core particle dispersion (B) was used.

<Comparative Example 3>
To the core particle dispersion (A) obtained in Synthesis Example 8, a 1 mol / liter hydrochloric acid aqueous solution was added to dissolve the dispersion stabilizer without adding the resin fine particle dispersion, followed by filtration, washing and washing. Thus, toner particles were obtained.

  A hydrophobic silica fine powder was externally added to the obtained toner particles in the same manner as in Example 1 to prepare a comparative toner.

<Comparative example 4>
To the core particle dispersion (B) obtained in Synthesis Example 9, a 1 mol / liter hydrochloric acid aqueous solution was added to dissolve the dispersion stabilizer without adding the resin fine particle dispersion, followed by filtration, washing, and drying. Thus, toner particles were obtained.

  A hydrophobic silica fine powder was externally added to the obtained toner particles in the same manner as in Example 1 to prepare a comparative toner.

<Comparative Example 5>
A toner of Comparative Example was produced in the same manner as in Example 1 except that the resin fine particle dispersion (g) was used in place of the resin fine particle dispersion (a).

<Example 9>
In Example 1, the toner of the present invention was produced in the same manner as in Example 1 except that the toner particles were produced as follows.

(Production of toner particles)
The fine resin particle dispersion (a) 25.0 obtained in Synthesis Example 1 is stirred with 500.0 parts by mass (solid content 100.0 parts by mass) of the core particle dispersion (C) obtained in Synthesis Example 10. Part by mass (solid content: 5.0 parts by mass) was added.

  Then, a 0.2 mol / liter aqueous hydrochloric acid solution was added dropwise at a dropping rate of 0.005 liter / min until the pH of the dispersion reached 1.70, and stirring was continued for 30 minutes to bring the surface of the core particles to the surface. Resin fine particles were fixed.

  The dispersion was heated to 60 ° C., and the stirring was continued for 3 hours while maintaining this temperature. Then, the dispersion was cooled, filtered, washed with water and dried to obtain toner particles.

<Comparative Example 6>
A toner of a comparative example was produced in the same manner as in Example 9, except that the resin fine particle dispersion (g) was used instead of the fine particle dispersion (a).

  For each toner obtained in Examples 1 to 9 and Comparative Examples 1 to 6, the isoelectric point pH (a) of the resin fine particles used, the isoelectric point pH (b) of the core particles, and the dispersion stabilizer are dissolved. The relationship of pH (c) is summarized in Table 2.

  Further, from the pH-zeta potential curve of the resin fine particles used for each toner, the value of the zeta potential at pH (b) indicating the isoelectric point of the corresponding core particle was determined and is shown together in Table 2.

  From Table 2, it can be seen that the value of the zeta potential at the isoelectric point pH (a) of the resin fine particles and the pH (b) indicating the isoelectric point of the core particles is largely dependent on the acid value derived from the sulfonic acid group. Recognize.

  Next, the average particle diameter and average circularity of each toner obtained in Examples 1 to 9 and Comparative Examples 1 to 6 were measured. Further, the BET specific surface area of each toner particle before external addition of the hydrophobic silica fine powder was measured. The results are summarized in Table 3.

  When the average circularity of each toner and the value of the BET specific surface area (S) of the toner particles are compared in Examples 1 and 2 and Comparative Examples 1 and 2 in Table 3, the toner of the comparative example is compared to the toner of the example. There is a tendency that the average circularity is small and the BET specific surface area (S) tends to be large. From this, it has been found that the pH at which the resin fine particles are fixed to the core particle is affected whether it is too high or too low.

Further, in Example 1, Examples 3 to 5, Example 7 and Example 8 using resin fine particles containing both sulfonic acid groups and carboxylic acid groups, each toner particle and the BET of the core particle used in this are used. It can be seen that the ratio to the specific surface area (S / S ₀ ) is relatively small and stable. In contrast, in Example 6 using a resin fine particle containing only sulfonic acid groups, the value of S / S ₀ is increased, it was found that it is difficult to smooth the particle surface. On the other hand, in Comparative Example 5 using a resin fine particle containing only carboxylic acid groups, although the value of S / S ₀ is particularly small, since the increase in the average particle size is observed, it was found that aggregation occurs .

  Further, in the comparison between Example 9 and Comparative Example 6 using the core particles (C), the average circularity tends to be small and the BET specific surface area (S) tends to be large, but the value of Comparative Example 6 is particularly remarkable. I found it inferior.

  Next, for each of the toners obtained in Examples 1 to 9 and Comparative Examples 1 to 6, the evaluation of blocking resistance, low-temperature fixability, image density, and image density reduction rate due to continuous image output will be described below. I went according to the procedure. The results are summarized in Table 4.

<Blocking resistance>
10 g of toner is weighed into a 100 ml capacity polycup and placed in a thermostat with an internal temperature of 50 ° C. and left for 7 days. Thereafter, the polycup is taken out, and the state change of the toner inside is visually evaluated. Judgment criteria are as follows.
A: No change B: There is an aggregate, but loosens immediately C: A little aggregate, difficult to loosen D: Many aggregates, not easily loosened E: Not loosened at all

<Low-temperature fixability>
A two-component developer is prepared by mixing toner and a magnetic fine particle-dispersed resin carrier (average particle diameter 35 μm) surface-coated with a silicone resin so that the toner concentration is 7.0% by mass.

  Next, the two-component developer is allowed to stand for 7 days at high temperature and high humidity (30 ° C./80%), and then left for another 3 days at room temperature and normal humidity (23 ° C./60%). Reset.

As a test machine, a commercially available full-color copying machine (CLC-700, manufactured by Canon Inc.) was used, and an unfixed toner image (toner applied amount per unit area of 0. 0 g / m ² ) on an image receiving paper (80 g / m ² ). 6 mg / cm ² ).

  The fixing test is performed using a fixing unit which is removed from the copying machine and modified so that the fixing temperature can be adjusted. The specific evaluation method is as follows.

  In a normal temperature and humidity environment (23 ° C, 60% RH), the process speed is set to 180 mm / s, the initial temperature is set to 120 ° C, and the set temperature is sequentially raised by 5 ° C, and the unfixed state at each temperature. Fix the image.

In the present invention, the low temperature fixability is the density reduction rate before and after rubbing when the low temperature offset is not observed and the obtained fixed image is rubbed 5 times with sylbon paper applied with a load of 4.9 kPa. Was the fixing start temperature, and the evaluation was made according to the following criteria.
A: Fixing start temperature is 120 ° C. (low temperature fixing performance is particularly excellent)
B: Fixing start temperature is 125 ° C. (low temperature fixing performance is good)
C: Fixing start temperature is 130 ° C. (low temperature fixing performance is at a level where there is no problem)
D: Fixing start temperature is 135 ° C. (low temperature fixing performance is slightly inferior)
E: Fixing start temperature is 140 ° C. (low temperature fixing performance is inferior)

<Image density>
Using a commercially available color laser printer (LBP-5900SE, manufactured by Canon), the toner in the cyan cartridge was taken out, 150 g of the toner thus prepared was filled therein, and the cartridge was mounted on the cyan station of the printer.

Under normal temperature and normal humidity (23 ° C., 60% RH), using an image receiving paper (Canon Office Planner 64 g / m ² ), the amount of applied toner per unit area is 0.35 mg / cm ² in a solid image. Adjustments were made to produce a fixed image.

The density of the produced image was measured using a reflection densitometer (500 Series Spectrodensitometer manufactured by X-rite) and evaluated according to the following criteria.
A: Reflection density is 1.50 or more (particularly high density is obtained and excellent)
B: Reflection density is 1.45 or more and less than 1.50 (sufficient density is obtained and good)
C: Reflection density is 1.40 or more and less than 1.45 (slightly low density, but no problem level)
D: Reflection density is 1.35 or more and less than 1.40 (density is low and slightly inferior)
E: Reflection density is less than 1.35 (particularly low density)

<Image density reduction rate>
Using the above-mentioned evaluation machine, using a receiving paper (Canon office planner 64 g / m ² ) under normal temperature and normal humidity (23 ° C., 60% RH), continuous printing of 5000 sheets of a 2% printing rate chart went.

After the continuous printing of 5000 sheets, a fixed image by a solid image was prepared, and the image density was similarly measured by the reflection densitometer (500 Series Spectrodensitometer manufactured by X-rite), and the image density was measured according to the following evaluation criteria. The decrease was evaluated.
A: Less than 5% reduction in image density (very little reduction in image density)
B: Image density decrease is 5% or more and less than 10% (less decrease in image density)
C: Decrease in image density is 10% or more and less than 15% (There is no problem in reducing image density)
D: Image density decrease is 15% or more and less than 20% (image density decrease is large)
E: Image density reduction is 20% or more (Image density reduction is very large)

  From Table 4, it can be seen that each of the toners evaluated this time has good performance in terms of low-temperature fixability.

  On the other hand, regarding blocking resistance, the toners of Comparative Examples 3 and 4 in which the coating layer of resin fine particles was not provided were significantly inferior. In other toners, the lower the acid value derived from the sulfonic acid of the resin fine particles used, the lower the tendency. Particularly, the blocking resistance of the toners of Comparative Examples 5 and 6 using resin fine particles containing only carboxylic acid groups is low, and the blocking resistance of the toner of Comparative Example 2 that did not sufficiently lower the pH in the toner particle preparation process. Moreover, the tendency to fall was seen. From this, it was found that these toners did not provide sufficient adhesion between the core particles and the coating layer.

  Further, regarding the image density due to the solid image and the image density reduction rate after the continuous printing of 5000 sheets, among the toners of the examples, in particular, the resin particles containing only sulfonic acid groups in Example 6 were used. It was suggested that the toner and the toner of Example 7 having a low total acid value had a large density reduction rate and were inferior in frictional charging stability. On the other hand, each of the toners of Comparative Examples 5 and 6 using resin fine particles containing only carboxylic acid groups also had a large density reduction rate, but these had a low initial density, and thus were essentially charged. It seems that it was insufficient.

Claims (7)

A step of producing core particles containing at least a binder resin, a colorant and a wax in an aqueous medium, adding resin fine particles to a dispersion in which the core particles are dispersed, and fixing the resin fine particles to the surface of the core particles A method for producing a toner comprising a step of:
The resin fine particles have self-dispersibility in water;
The pH (a) indicating the isoelectric point determined by measuring the zeta potential in water of the resin fine particles is smaller than the pH (b) indicating the isoelectric point determined by measuring the zeta potential in water of the core particle,
the zeta potential of the resin fine particles in water at pH (b) is −5.0 mV or less,
In the step of fixing the resin fine particles to the surface of the core particles, the dispersion is adjusted so that the pH of the dispersion is higher than pH (a) -0.30 and lower than pH (b). A method for producing a toner, comprising adhering to a particle surface. A step of producing core particles containing at least a binder resin, a colorant, and a wax in an aqueous medium in which a dispersion stabilizer is dispersed; adding resin fine particles to the dispersion in which the core particles are dispersed; By adhering the dispersion stabilizer to the surface of the core particle and adjusting the pH of the dispersion to dissolve the dispersion stabilizer, A method for producing a toner having a step of fixing to a surface,
The resin fine particles have self-dispersibility in water;
The pH (a) indicating the isoelectric point determined by measuring the zeta potential in water of the resin fine particles is smaller than the pH (b) indicating the isoelectric point determined by measuring the zeta potential in water of the core particle,
the zeta potential of the resin fine particles in water at pH (b) is −5.0 mV or less,
When the pH at which the dispersion stabilizer is dissolved is defined as pH (c), pH (a) <pH (c) <pH (b)
In the step of fixing the resin fine particles to the surface of the core particle, the pH of the dispersion is adjusted to be greater than pH (a) -0.30 and less than pH (c). Toner manufacturing method.   3. The toner manufacturing method according to claim 1, wherein the resin fine particles are composed of a resin containing at least a sulfonic acid group and a carboxylic acid group.   The resin particles have an acid value derived from a sulfonic acid group of 2.0 to 15.0 mg KOH / g, an acid value derived from a carboxylic acid group of 3.0 to 20.0 mg KOH / g, and a sulfone group. 4. The method for producing a toner according to claim 3, wherein the sum of the acid value derived from the acid group and the acid value derived from the carboxylic acid group is 8.0 to 30.0 mgKOH / g.   The core particles are prepared by suspending a polymerizable monomer composition containing at least a polymerizable monomer, a colorant, and a wax in an aqueous medium in which a dispersion stabilizer is dispersed. 5. The method for producing a toner according to claim 1, wherein the toner is obtained through a step of polymerizing a toner.   The core particles are suspended in an aqueous medium in which a dispersion stabilizer is dispersed, at least including a binder resin, a colorant, a wax, and a solvent capable of dissolving the binder resin. The toner production method according to claim 1, wherein the toner is obtained through a step of removing the solvent.   A toner manufactured by the toner manufacturing method according to claim 1.