JP2018049244A - Toner for electrostatic charge image development, electrostatic charge image developer, toner cartridge, process cartridge, image forming apparatus, and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner for electrostatic charge image development which suppresses generation of a color point when an image is formed using a toner after stored under high temperature and high humidity environment.SOLUTION: A toner has: toner particles which have a sea-island structure having a sea portion containing a binder resin and an island portion containing a mold release agent, where in a degree B of maldistribution of the island portion containing the mold releasing agent represented by formula (1) (formula (1): degree B of maldistribution=2d/D (D: equivalent circle diameter (μm) of toner, and d: distance (μm) between the center of gravity of the toner and the center of gravity of the island portion containing the mold releasing agent), the most frequent value in the distribution of the degree B of maldistribution is 0.75 or more and 0.98 or less, skewness in the distribution of the degree B of maldistribution is -1.10 or more and -0.50 or less, and average circularity is 0.94 or more and 0.98 or less; and an external additive containing first silica particles having an average primary particle diameter Da (nm) and second silica particles having an average primary particle diameter Db (nm) (satisfying expression (A1): 80≤Da≤120, expression (A2):120≤Db≤200 and expression (A3):15≤Db-Da≤120).SELECTED DRAWING: None

Description

  The present invention relates to an electrostatic charge image developing toner, an electrostatic charge image developer, a toner cartridge, a process cartridge, an image forming apparatus, and an image forming method.

  In electrophotographic image formation, a toner is used as an image forming material. For example, a toner containing toner particles containing a binder resin and a colorant and an external additive externally added to the toner particles is used. Many are used.

For example, Patent Document 1 states that “a core material having an electric resistance of 1 × 10 ⁷ Ωcm to 1 × 10 ¹⁰ Ωcm at 30 ° C. and 85% RH under an electric field of 4800 V / cm; A carrier layer having a coating layer containing a resin, and toner particles; first silica particles having a volume average particle diameter of 70 nm to 200 nm surface-treated with oil; and surface-treated with oil An electrostatic charge image developer including a toner having an external additive containing second silica particles having a volume average particle diameter of 10 nm to 50 nm is disclosed.
Patent Document 2, "at least a binder resin, a coloring particles containing a colorant and a releasing agent, a specific surface area of ^{40m 2} / ^g~400m 2 / g, and an average pore diameter on the surface 1.0nm~6 And a toner having inorganic particles having pores of 0.0 nm ”.

Patent Document 3 states that “in a dry toner containing at least a toner binder, a colorant, and a wax, the wax is encapsulated in the form of fine particles in the toner particles, and from the surface vicinity to the inside of the toner. The dry toner is characterized in that the concentration of wax existing and in the vicinity of the surface of the toner is higher than the concentration of wax existing in the toner. "
In Patent Document 4, “a toner containing at least a binder resin, a wax, and inorganic fine powder as an external additive, the binder resin contains a polyester resin, and the content of the wax is The amount of the toner is 3.0 parts by mass or more and 20.0 parts by mass or less with respect to 100 parts by mass of the binder resin, and the toner uses an ATR method under conditions of Ge as an ATR crystal and 45 ° as an incident angle of infrared light. in the measured obtained was FT-IR spectrum, the maximum absorption peak intensity of 2843cm ^-1 or 2853cm ^-1 the range Pa, the maximum absorption peak intensity of 1713 cm ^-1 or 1723 cm ^-1 or less in the range between Pb, ATR method In an FT-IR spectrum obtained by measurement under the conditions of KRS5 as an ATR crystal and 45 ° as an infrared light incident angle, 2843 cm −1 or more and 28 The maximum absorption peak intensity of 3 cm ^-1 or less in the range Pc, and the maximum absorption peak intensity of 1713 cm ^-1 or 1723 cm ^-1 following range when the Pd, and satisfies the following relationship formula (1) Toner, 1.05 ≦ P1 / P2 ≦ 2.00 Expression (1) ”is disclosed.

Japanese Patent Laid-Open No. 2015-230376 JP 2011-002559 A JP 2004-145243 A JP 2011-158758 A

Conventionally, a toner having toner particles in which a release agent is unevenly distributed in the surface layer portion is likely to cause thermal aggregation between toner particles in a high temperature and high humidity environment. In order to suppress thermal aggregation between the toner particles, for example, an external additive containing only large-diameter silica particles (for example, a volume average particle size of 80 nm to 200 nm) is externally added to the toner particles as silica particles. It is known.
However, even with an electrostatic charge image developing toner in which large-diameter silica particles are externally added to toner particles, when an image is formed after storage in a high-temperature and high-humidity environment, color points may occur. .

  Accordingly, an object of the present invention is to provide an electrostatic charge image developing toner having toner particles in which a release agent is unevenly distributed in a surface layer portion and an external additive containing silica particles, and the average primary particle size is 120 nm as silica particles. Provided is a toner for developing an electrostatic charge image in which generation of a color point is suppressed even when an image is formed after storage in a high-temperature and high-humidity environment as compared with the case where silica particles of 200 nm or less are contained alone. That is.

  The above problem is solved by the following means. That is,

The invention according to claim 1
It has a sea-island structure including a binder resin and a release agent, and has a sea part containing the binder resin and an island part containing the release agent, and includes the release agent represented by the following formula (1) The mode of the distribution of the uneven distribution degree B of the island is 0.75 or more and 0.98 or less, the skewness of the distribution of the uneven distribution degree B is −1.10 or more and −0.50 or less, and the average circularity Toner particles having a viscosity of 0.94 or more and 0.98 or less;
When the average primary particle diameter of the first silica particles is Da (nm) and the average primary particle diameter of the second silica particles is Db (nm), including the first silica particles and the second silica particles, the following formula ( An external additive satisfying the relationship of A1) to formula (A3);
A toner for developing an electrostatic charge image.
Formula (1): Uneven distribution degree B = 2d / D
(In formula (1), D represents the equivalent-circle diameter (μm) of the toner particles in the cross-sectional observation of the toner particles. D represents the center of gravity of the island portion including the release agent from the center of the toner particles in the cross-sectional observation of the toner particles. The distance (μm) is shown.)
Formula (A1): 80 ≦ Da ≦ 120
Formula (A2): 120 ≦ Db ≦ 200
Formula (A3): 15 ≦ Db−Da ≦ 120

The invention according to claim 2
The electrostatic image developing toner according to claim 1, wherein the second silica particles have an average circularity of 0.9 or more and 1.0 or less.
The invention according to claim 3
The electrostatic image developing toner according to claim 2, wherein the first silica particles have an average circularity of 0.9 or more and 1.0 or less.

The invention according to claim 4
The electrostatic image developing toner according to claim 1, wherein the binder resin is a polyester resin.
The invention according to claim 5
The electrostatic image developing toner according to claim 1, wherein the binder resin is a styrene (meth) acrylic resin.

The invention according to claim 6
An electrostatic charge image developer comprising the electrostatic charge image developing toner according to claim 1.

The invention according to claim 7 provides:
Containing the toner for developing an electrostatic charge image according to any one of claims 1 to 5,
A toner cartridge to be attached to and detached from the image forming apparatus.

The invention according to claim 8 provides:
A developing means for containing the electrostatic charge image developer according to claim 6 and developing the electrostatic charge image formed on the surface of the image carrier as a toner image by the electrostatic charge image developer,
A process cartridge attached to and detached from the image forming apparatus.

The invention according to claim 9 is:
An image carrier,
Charging means for charging the surface of the image carrier;
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image carrier;
Developing means for containing the electrostatic charge image developer according to claim 6 and developing the electrostatic charge image formed on the surface of the image carrier as a toner image by the electrostatic charge image developer;
Transfer means for transferring a toner image formed on the surface of the image carrier to the surface of a recording medium;
Fixing means for fixing the toner image transferred to the surface of the recording medium;
An image forming apparatus comprising:

The invention according to claim 10 is:
A charging step for charging the surface of the image carrier;
An electrostatic charge image forming step of forming an electrostatic charge image on the surface of the charged image carrier;
A developing step of developing an electrostatic charge image formed on the surface of the image carrier as a toner image with the electrostatic charge image developer according to claim 6;
A transfer step of transferring a toner image formed on the surface of the image carrier to the surface of a recording medium;
A fixing step of fixing the toner image transferred to the surface of the recording medium;
An image forming method comprising:

  According to the first, second, third, fourth, or fifth aspect of the invention, in the electrostatic image developing toner having toner particles in which a release agent is unevenly distributed in the surface layer portion and an external additive containing silica particles. As compared with the case where silica particles having an average primary particle size of 120 nm or more and 200 nm or less are contained alone, the generation of color points is suppressed even when an image is formed after storage in a high temperature and high humidity environment. An electrostatic charge image developing toner is provided.

  According to the invention of claim 6, 7, 8, 9, or 10, the toner for developing an electrostatic image comprising toner particles in which a release agent is unevenly distributed in the surface layer portion and an external additive containing silica particles. In the case where an image is formed after storage in a high-temperature and high-humidity environment, compared to the case where a toner for developing an electrostatic image containing silica particles having an average primary particle size of 120 nm to 200 nm alone is applied as silica particles. Even in such a case, an electrostatic charge image developer, a toner cartridge, a process cartridge, an image forming apparatus, or an image forming method in which generation of a color point is suppressed is provided.

1 is a schematic configuration diagram illustrating an image forming apparatus according to an exemplary embodiment. It is a schematic block diagram which shows the process cartridge which concerns on this embodiment. It is a schematic diagram for demonstrating the power feed addition method. FIG. 6 is a diagram illustrating a distribution of a degree of uneven distribution B of a release agent domain in the toner according to the exemplary embodiment.

  Hereinafter, an embodiment which is an example of the present invention will be described in detail.

<Toner for electrostatic image development>
The toner for developing an electrostatic charge image (hereinafter referred to as “toner”) according to the exemplary embodiment includes toner particles including a binder resin and a release agent, and an external additive including silica particles.
The toner particles have a sea-island structure having a sea part containing a binder resin and an island part containing a release agent. In this sea-island structure, the mode of distribution of the uneven distribution degree B of the island portion including the releasing agent represented by the formula (1) is not less than 0.75 and not more than 0.98, and the distribution distribution of the uneven distribution degree B is distorted. The degree is from −1.10 to −0.50. Further, the average circularity is 0.94 or more and 0.98 or less.
Formula (1): Unevenness B = 2d / D
(In the formula (1), D represents the equivalent circle diameter (μm) of the toner particles in the cross-sectional observation of the toner particles. The distance (μm) is shown.)
The silica particles have first silica particles and second silica particles.
And when the average primary particle diameter of the first silica particles is Da (nm) and the average primary particle diameter of the second silica particles is Db (nm), the following formulas (A1) to (A3) are satisfied. .
Formula (A1): 80 ≦ Da ≦ 120
Formula (A2): 120 ≦ Db ≦ 200
Formula (A3): 15 ≦ Db−Da ≦ 120

Conventionally, a toner having toner particles in which a release agent is unevenly distributed in the surface layer portion is likely to cause thermal aggregation between toner particles in a high temperature and high humidity environment. Therefore, for the purpose of suppressing thermal aggregation between toner particles, for example, it is known that an external additive containing only large-diameter silica particles (for example, a volume average particle size of 80 nm or more and 200 nm or less) is externally added to the toner particles. It has been.
However, even an electrostatic charge image developing toner in which large-diameter silica particles are externally added to toner particles, the image is stored after the toner is stored in a high-temperature and high-humidity environment (for example, 45 ° C., 95% RH). When formed, a color point may occur.

  The toner after storage in a high-temperature and high-humidity environment where color points were generated was investigated by observation with a scanning electron microscope. As a result, in the toner after storage, the convex portions and the concave portions of the toner particles are often in contact with the convex portions and the convex portions of the toner particles. It has been found that the toner particles in contact with each other are strongly thermally aggregated.

  For example, when toner particles and an external additive containing silica particles are mixed and mixed by mixing and stirring, the silica particles easily adhere to the convex portions of the toner particles. On the other hand, silica particles are less likely to adhere to the concave portions of the toner particles than the convex portions. Large-diameter silica particles tend to roll on the toner particles and easily move to the concave portions of the toner particles. However, in the concave portions of the toner particles, a portion that is not covered with the large-diameter silica particles may be generated. Therefore, even if large-diameter silica particles are externally added for the purpose of suppressing thermal aggregation between the toner particles, a portion where the surface of the toner particles not covered with the silica particles is exposed is generated. Then, it is considered that thermal aggregation of toner particles occurs in the toner after being stored in a high-temperature and high-humidity environment starting from the exposed portion.

  On the other hand, the toner according to the present embodiment includes an external additive including the first silica particles and the second silica particles satisfying the relations of the above-described formulas (A1) to (A3), and the sea part including the binder resin. And externally added to toner particles having a sea-island structure with an island containing a release agent, suppresses the generation of color points when images are formed using toner after storage in a high-temperature, high-humidity environment Is done. The reason for this is not clear, but is presumed as follows.

  When an external additive containing toner particles, small-diameter first silica particles, and large-diameter second silica particles is mixed and stirred, first, both the first silica particles and the second silica particles adhere to the toner particles. The first silica particles having a small diameter adhering to the toner particles adhere mainly to the convex portions of the toner particles and have a stronger adhesion to the toner particles than the second silica particles having a large diameter. Easy to stay. In addition, since the large-diameter second silica particles have a weaker adhesion to the toner particles than the small-diameter first silica particles, they easily roll on the toner particles and easily move to the concave portions of the toner particles. As a result, the first silica particles can cover the convex portions of the toner particles, and the second silica particles can cover the concave portions of the toner particles, so that the surface of the toner particles can be coated almost uniformly. Therefore, exposure of the toner particle surface is suppressed.

  By the way, for example, when the first silica particles having a small diameter and the second silica particles having a large diameter are externally added to the toner particles in which most of the release agent contained in the toner particles is present on the surface, silica particles are added to the surface of the toner particles. Particles are easily trapped. However, when too much release agent is present on the surface of the toner particles, the silica particles are easily embedded in the toner particles. In this case, the spacer effect (buffering effect) due to the silica particles may be reduced, and it may be difficult to obtain the effect of suppressing thermal aggregation between the toner particles.

  Therefore, in the toner according to the exemplary embodiment, the first silica particles and the second silica particles are added to the toner particles having a sea-island structure having the sea part containing the binder resin and the island part containing the release agent. Attached. In this toner particle, the release agent is unevenly distributed on the surface layer portion of the toner particle, and is distributed with a gradient from the surface layer portion of the toner particle to the inside, and the release agent is appropriately present on the surface. Therefore, both the above-described silica particles can be easily captured on the surface of the toner particles, and the embedding of the silica particles is suppressed. In addition, in the toner particles, for example, a release agent may exist on the surface forming the concave portions of the toner particles. The second silica particles that roll on the toner particles and move to the recesses are captured by the release agent present on the surface of the recesses and are difficult to move from the recesses. For this reason, the surface of the toner particles is covered with the first silica particles having a small diameter and the concave portions of the toner particles are covered with a second silica particle having a large diameter so that the toner particles are coated in a nearly uniform state. The disilica particles are difficult to move from the recess. Thereby, the toner according to the exemplary embodiment is considered to suppress thermal aggregation between toner particles when stored in a high temperature and high humidity environment.

  When the average circularity of the toner particles is less than 0.94, the shape of the toner particles becomes indefinite, the fluidity is lowered, and thermal aggregation is likely to occur when stored in a high temperature and high humidity environment. Further, when the average circularity of the toner particles exceeds 0.98, the ratio of toner particles close to a sphere increases, so that the concave portions of the toner particles are reduced. In addition, the ratio of the release agent present in the recess is also reduced. Even if the large-diameter silica particles roll on the toner particles, the concave portions are few and the release agent trapped by the concave portions is also small, so that the large-diameter silica particles are easily released from the toner particles, and the toner particles have exposed portions. It tends to occur. Thereby, thermal aggregation is likely to occur when stored in a high temperature and high humidity environment. For this reason, it is considered that when the average circularity of the toner particles is 0.94 or more and 0.98 or less, thermal aggregation between the toner particles when stored in a high temperature and high humidity environment is easily suppressed.

  For the above reasons, it is assumed that the toner according to the present embodiment has the above-described configuration, so that generation of a color point is suppressed when an image is formed using the toner stored in a high temperature and high humidity environment. Is done.

  Hereinafter, details of the toner according to the exemplary embodiment will be described.

  The toner according to the exemplary embodiment includes toner particles and an external additive.

(Toner particles)
The toner particles have a sea-island structure having a sea part containing a binder resin and an island part containing a release agent. That is, the toner particles have a sea-island structure in which the release agent exists in an island shape in the continuous phase of the binder resin. In the toner particles having the sea-island structure, the mode of distribution of the uneven distribution degree B of the release agent domain (island part including the release agent) is 0.75 or more and 0.98 or less, and the uneven distribution degree B The skewness of the distribution of −1.10 or more and −0.50 or less.
Note that the release agent domain is preferably not present in the central portion (center of gravity) of the toner in the cross-sectional observation of the toner from the viewpoint of suppressing defective peeling.

  Here, the toner particles having the above characteristics will be described. The uneven distribution degree B of the island portion including the release agent (hereinafter also referred to as “release agent domain”) is an index indicating how far the gravity center of the release agent domain is separated from the gravity center of the toner particles. The uneven distribution degree B indicates that the release agent domain is present near the toner surface as the value is larger, and the release agent domain is present near the center of the toner particle as the value is smaller. The mode of distribution of the uneven distribution degree B indicates a portion where the release agent domain is most present in the radial direction of the toner particles. On the other hand, the skewness of the distribution of the uneven distribution degree B indicates the symmetry of the distribution. Specifically, the skewness of the distribution of the uneven distribution degree B indicates the degree of tailing of the distribution from the mode value. That is, the skewness of the distribution of the uneven distribution degree B indicates how much distribution of the release agent domain exists from the most numerous parts in the radial direction of the toner particles.

  That is, the mode value of the distribution of the uneven distribution degree B of the release agent domains is in the range of 0.75 or more and 0.98 or less means that the release agent domains are most present in the surface layer portion of the toner particles. It is shown that. When the skewness of the distribution of the uneven distribution degree B of the release agent domain is in the range of −1.10 or more and −0.50 or less, the release agent domain is directed from the surface layer portion of the toner particle toward the inside. , It is distributed with a gradient (see FIG. 4).

  As described above, the toner particles satisfying the above-described range of the distribution mode B of the distribution degree B of the uneven distribution degree of the release agent domain have a gradient and the inside of the toner particle having a gradient while the release agent domain is most present in the surface layer portion. The toner particles are distributed toward the surface layer.

  In toner particles having a sea-island structure, the mode of distribution of the degree of uneven distribution B of the release agent domain (island containing the release agent) is when an image is formed after storage in a high-temperature and high-humidity environment. However, it is preferably 0.75 or more and 0.95 or less, more preferably 0.80 or more and 0.95 or less, and still more preferably 0.85 or more and 0.90 or less in that the generation of color points is further suppressed.

  The skewness of the distribution of the uneven distribution degree B of the release agent domain (islands including the release agent) is −1.10 or more and −0.50 or less, and an image was formed after storage in a high-temperature and high-humidity environment. Even if it is a case, -1.00 or more and -0.60 or less are preferable and -0.95 or more and -0.65 or less are more preferable at the point by which generation | occurrence | production of a color point is suppressed more.

Here, a method for confirming the sea-island structure of toner particles will be described.
The sea-island structure of the toner particles is confirmed by, for example, a method of observing the cross section of the toner particles with a transmission electron microscope, or a method of observing the cross section of the toner particles with ruthenium tetroxide and observing with a scanning electron microscope. A method of observing with a scanning electron microscope is preferable in that the release agent domain in the cross section of the toner particles can be observed more clearly. The scanning electron microscope may be any model well known to those skilled in the art, and examples thereof include SU8020 manufactured by Hitachi High-Tech, JSM-7500F manufactured by JEOL.
A specific observation method is as follows. First, after embedding toner particles to be measured in an epoxy resin, the epoxy resin is cured. The cured product is thinned by a microtome equipped with a diamond blade to obtain an observation sample in which the cross section of the toner particles is exposed. The observation sample of the flakes is dyed with ruthenium tetroxide, and the cross section of the toner particles is observed with a scanning electron microscope. By this observation method, a sea-island structure in which a release agent having a luminance difference (contrast) exists in an island shape is observed in the cross section of the toner particle due to a difference in the degree of dyeing in the continuous phase of the binder resin. .

Next, a method for measuring the uneven distribution degree B of the release agent domain will be described.
The measurement of the uneven distribution degree B of the release agent domain is performed as follows. First, using a sea-island structure confirmation method, an image is recorded at a magnification at which the cross section of one toner particle can be viewed. The recorded image is subjected to image analysis under the condition of 0.010000 μm / pixel using image analysis software (WinROOF manufactured by Mitani Corporation). By this image analysis, the shape of the cross section of the toner particles is extracted based on the luminance difference (contrast) between the epoxy resin used for embedding and the binder resin of the toner particles. Based on the extracted cross-sectional shape of the toner particles, a projected area is obtained. Then, the equivalent circle diameter is obtained from this projected area. The equivalent circle diameter is calculated by the formula: 2√ (projected area / π). The obtained equivalent circle diameter is defined as the equivalent circle diameter D of the toner particles in the cross-sectional observation of the toner particles.
On the other hand, the position of the center of gravity is obtained based on the cross-sectional shape of the extracted toner particles. Subsequently, the shape of the release agent domain is extracted based on the luminance difference (contrast) between the binder resin and the release agent, and the position of the center of gravity of the release agent domain is obtained. Specifically, for each of the center of gravity positions, the number of pixels in the region is n, and the xy coordinates of each pixel are x _i , y _i (i = , N), the x coordinate of the center of gravity is obtained by dividing the sum of each x _i coordinate value by n, and the y coordinate of the center of gravity is obtained by dividing the sum of each y _i coordinate value by n. Then, the distance between the centroid position of the cross section of the toner particles and the centroid position of the release agent domain is obtained. The obtained distance is defined as a distance d from the center of gravity of the toner particle to the center of gravity of the island portion including the release agent in the cross-sectional observation of the toner particle.
Finally, the uneven distribution degree B of the release agent domain is obtained from each circle-equivalent diameter D and the distance d by Equation (1): uneven distribution degree B = 2d / D. Then, the same operation as described above is performed for each of the plurality of release agent domains existing in the cross section of one toner particle, and the uneven distribution degree B of the release agent domains is obtained.

Next, a method for calculating the mode of the distribution of the uneven distribution degree B of the release agent domain will be described.
First, the above-described degree of uneven distribution B of the release agent domain is measured for 200 toner particles. The data of the degree of uneven distribution B of each obtained release agent domain is subjected to statistical analysis processing in a data interval from 0 to 0.01 to obtain the distribution of the degree of uneven distribution B. The mode of the obtained distribution, that is, the value of the data section that appears most frequently in the distribution of the uneven distribution degree B of the release agent domain is obtained. And the value of this data section is made the mode value of the distribution of the uneven distribution degree B of the release agent domain.

Next, a method for calculating the skewness of the distribution of the uneven distribution degree B of the release agent domain will be described.
First, as described above, the distribution of the uneven distribution degree B of the release agent domain is obtained. The skewness of the distribution of the uneven distribution degree B is obtained based on the obtained following formula. In the following formula, the skewness is Sk, the number of data of the uneven distribution degree B of the release agent domain is n, and the value of the data of the uneven distribution degree B of each release agent domain is x _i (i = 1, 2,... n) The average value of the entire data of the uneven distribution degree B of the release agent domain is x (x with an upper bar), and the standard deviation of the entire data of the uneven distribution degree B of the release agent domain is s.

  A method for satisfying the distribution characteristics of the uneven distribution degree B of the release agent domain in the toner particles will be described in the toner manufacturing method.

  The average circularity of the toner particles is 0.94 or more and 0.98 or less as the average circularity of the toner particles. Even when an image is formed after storage in a high-temperature and high-humidity environment, 0.95 or more and 0.98 or less is preferable, and 0.96 or more and 0.98 or less is preferable in that generation of color points is suppressed. More preferred.

The average circularity of the toner particles is measured with a FPIA-3000 manufactured by Sysmex. This system employs a method in which particles dispersed in water or the like are measured by a flow-type image analysis method. The sucked particle suspension is guided to a flat sheath flow cell, and a flat sample flow is generated by the sheath liquid. It is formed. By irradiating the sample stream with stroboscopic light, the passing particles are captured as a still image by a CCD (Charge Coupled Device) camera through the objective lens. The captured particle image is subjected to two-dimensional image processing, and the circularity is calculated from the projected area and the perimeter. Regarding the circularity, at least 4,000 or more images are analyzed, and the average circularity is obtained by statistical processing.
Formula: Circularity = circle equivalent diameter perimeter / perimeter = [2 × (Aπ) ^1/2 ] / PM
In the above formula, A represents the projected area, and PM represents the perimeter.
Note that the HPF mode (high resolution mode) is used for the measurement, and the dilution factor is 1.0. In analyzing the data, the circularity analysis range is set to a range of 0.40 to 1.00 for the purpose of removing measurement noise.
The toner to be measured is dispersed in water containing a surfactant, and the toner particles (developer) to be measured are dispersed, and then subjected to ultrasonic treatment to remove toner particles from which the external additives are subjected to measurement. .

Hereinafter, the components of the toner particles will be described.
The toner particles include a binder resin and a release agent. The toner particles may contain a colorant and other additives as necessary.

-Binder resin-
Examples of the binder resin include styrenes (eg, styrene, parachlorostyrene, α-methylstyrene, etc.), (meth) acrylic acid esters (eg, methyl acrylate, ethyl acrylate, n-propyl acrylate, acrylic acid). n-butyl, lauryl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, lauryl methacrylate, 2-ethylhexyl methacrylate, etc.), ethylenically unsaturated nitriles (for example, acrylonitrile, Methacrylonitrile, etc.), vinyl ethers (eg, vinyl methyl ether, vinyl isobutyl ether, etc.), vinyl ketones (vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropenyl ketone, etc.), olefins (eg, ethylene, propylene, etc.) Emissions, a homopolymer of a monomer such as butadiene) and the like, or a vinyl-based resin composed of these monomers with two or more combinations copolymer.
As the binder resin, for example, epoxy resin, polyester resin, polyurethane resin, polyamide resin, cellulose resin, polyether resin, non-vinyl resin such as modified rosin, a mixture of these with the vinyl resin, or these Examples also include a graft polymer obtained by polymerizing a vinyl monomer in the coexistence.
These binder resins may be used alone or in combination of two or more.

A polyester resin is also suitable as the binder resin.
Examples of the polyester resin include known polyester resins.

  As a polyester resin, the condensation polymer of polyhydric carboxylic acid and polyhydric alcohol is mentioned, for example. In addition, as a polyester resin, a commercial item may be used and what was synthesize | combined may be used.

Examples of the polyvalent carboxylic acid include aliphatic dicarboxylic acids (eg, oxalic acid, malonic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, succinic acid, alkenyl succinic acid, adipic acid, sebacic acid, etc.) Alicyclic dicarboxylic acids (for example, cyclohexanedicarboxylic acid), aromatic dicarboxylic acids (for example, terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, etc.), their anhydrides, or lower (for example, having 1 or more carbon atoms) 5 or less) alkyl esters. Among these, as polyvalent carboxylic acid, aromatic dicarboxylic acid is preferable, for example.
The polyvalent carboxylic acid may be used in combination with a dicarboxylic acid or a trivalent or higher carboxylic acid having a crosslinked structure or a branched structure. Examples of the trivalent or higher carboxylic acid include trimellitic acid, pyromellitic acid, anhydrides thereof, and lower (for example, having 1 to 5 carbon atoms) alkyl esters.
Polyvalent carboxylic acid may be used individually by 1 type, and may use 2 or more types together.

Examples of the polyhydric alcohol include aliphatic diols (for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, etc.), alicyclic diols (for example, cyclohexanediol, cyclohexanedimethanol, Hydrogenated bisphenol A, etc.) and aromatic diols (for example, ethylene oxide adducts of bisphenol A, propylene oxide adducts of bisphenol A, etc.). Among these, as the polyhydric alcohol, for example, aromatic diols and alicyclic diols are preferable, and aromatic diols are more preferable.
As the polyhydric alcohol, a trihydric or higher polyhydric alcohol having a crosslinked structure or a branched structure may be used together with the diol. Examples of the trihydric or higher polyhydric alcohol include glycerin, trimethylolpropane, and pentaerythritol.
A polyhydric alcohol may be used individually by 1 type, and may use 2 or more types together.

The glass transition temperature (Tg) of the polyester resin is preferably 50 ° C. or higher and 80 ° C. or lower, and more preferably 50 ° C. or higher and 65 ° C. or lower.
The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), and more specifically, described in the method for determining the glass transition temperature in JIS K7121-1987 “Method for Measuring Transition Temperature of Plastic”. It is determined by “extrapolated glass transition start temperature”.

The weight average molecular weight (Mw) of the polyester resin is preferably from 5,000 to 1,000,000, and more preferably from 7,000 to 500,000.
The number average molecular weight (Mn) of the polyester resin is preferably from 2,000 to 100,000.
The molecular weight distribution Mw / Mn of the polyester resin is preferably 1.5 or more and 100 or less, and more preferably 2 or more and 60 or less.
The weight average molecular weight and the number average molecular weight are measured by gel permeation chromatography (GPC). The molecular weight measurement by GPC is performed with a THF solvent using a Tosoh GPC / HLC-8120GPC as a measuring device and a Tosoh column / TSKgel SuperHM-M (15 cm). The weight average molecular weight and the number average molecular weight are calculated using a molecular weight calibration curve prepared from a monodisperse polystyrene standard sample from this measurement result.

The polyester resin is obtained by a well-known manufacturing method. Specifically, for example, the polymerization temperature is set to 180 ° C. or higher and 230 ° C. or lower, the pressure in the reaction system is reduced as necessary, and the reaction is performed while removing water and alcohol generated during the condensation.
In addition, when the monomer of the raw material is not dissolved or compatible at the reaction temperature, a solvent having a high boiling point may be added and dissolved as a solubilizing agent. In this case, the polycondensation reaction is performed while distilling off the solubilizer. If there is a monomer with poor compatibility, it is recommended to condense the monomer with poor compatibility with the monomer and the acid or alcohol to be polycondensed in advance before polycondensing with the main component. .

A styrene (meth) acrylic resin is also suitable. Styrene (meth) acrylic resin is composed of styrene polymerizable monomer (polymerizable monomer having styrene skeleton) and (meth) acrylic polymerizable monomer (polymerizable monomer having (meth) acryloyl skeleton). ) At least a copolymer. The styrene (meth) acrylic resin includes, for example, a copolymer of the aforementioned styrene monomer and the aforementioned (meth) acrylic acid ester monomer.
“(Meth) acryl” is an expression including both “acryl” and “methacryl”.

Specific examples of the styrenic polymerizable monomer include styrene and alkyl-substituted styrene (for example, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, etc.), halogen-substituted styrene (for example, 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, etc.), vinylnaphthalene, and the like. A styrene-type polymerizable monomer may be used individually by 1 type, and may use 2 or more types together.
Among these, as the styrene polymerizable monomer, styrene is preferable from the viewpoint of easy reaction, easy control of reaction, and availability.

  Specific examples of the (meth) acrylic polymerizable monomer include (meth) acrylic acid and (meth) acrylic acid ester. Examples of (meth) acrylic acid esters include (meth) acrylic acid alkyl esters (for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and (meth) acrylic acid n. -Butyl, n-pentyl (meth) acrylate, n-hexyl acrylate, n-heptyl (meth) acrylate, n-octyl (meth) acrylate, n-decyl (meth) acrylate, (meth) acrylic acid n-dodecyl, n-lauryl (meth) acrylate, n-tetradecyl (meth) acrylate, n-hexadecyl (meth) acrylate, n-octadecyl (meth) acrylate, isopropyl (meth) acrylate, (meth) Isobutyl acrylate, t-butyl (meth) acrylate, isopentyl (meth) acrylate, (meth) acrylic acid Mill, neopentyl (meth) acrylate, isohexyl (meth) acrylate, isoheptyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, (meth) acryl Acid t-butylcyclohexyl, etc.), (meth) acrylic acid aryl esters (for example, phenyl (meth) acrylate, biphenyl (meth) acrylate, diphenylethyl (meth) acrylate, t-butylphenyl (meth) acrylate), (Meth) acrylic acid terphenyl etc.), (meth) acrylic acid dimethylaminoethyl, (meth) acrylic acid diethylaminoethyl, (meth) acrylic acid methoxyethyl, (meth) acrylic acid 2-hydroxyethyl, (meth) acrylic acid β-carboxyethyl, (meta ) Acrylamide and the like. The (meth) acrylic acid-based polymerizable monomer may be used alone or in combination of two or more.

  The copolymerization ratio (mass basis, styrene polymerizable monomer / (meth) acrylic polymerizable monomer) between the styrene polymerizable monomer and the (meth) acrylic polymerizable monomer is, for example, 85. / 15 to 70/30 is preferable.

  The styrene (meth) acrylic resin may have a crosslinked structure. The styrene (meth) acrylic resin having a cross-linked structure is, for example, a cross-linked cross-link by at least copolymerizing a styrene polymerizable monomer, a (meth) acrylic acid polymerizable monomer, and a cross-linkable monomer. Things.

Examples of the crosslinkable monomer include bifunctional or higher functional crosslinking agents.
Examples of the bifunctional crosslinking agent include divinylbenzene, divinylnaphthalene, and di (meth) acrylate compounds (for example, diethylene glycol di (meth) acrylate, methylenebis (meth) acrylamide, decanediol diacrylate, glycidyl (meth) acrylate, etc.) , Polyester type di (meth) acrylate, 2-([1′-methylpropylideneamino] carboxyamino) ethyl methacrylate, and the like.
Examples of the polyfunctional crosslinking agent include tri (meth) acrylate compounds (for example, pentaerythritol tri (meth) acrylate, trimethylolethane tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, etc.), tetra (meth) acrylate Compound (for example, pentaerythritol tetra (meth) acrylate, oligoester (meth) acrylate, etc.), 2,2-bis (4-methacryloxy, polyethoxyphenyl) propane, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, Examples include triallyl trimellitate and diaryl chlorendate.
The copolymerization ratio of the crosslinkable monomer to the total monomer (mass basis, crosslinkable monomer / total monomer) is preferably, for example, 2/1000 to 30/1000.

The glass transition temperature (Tg) of the styrene (meth) acrylic resin is, for example, 50 ° C. or higher and 75 ° C. or lower, preferably 55 ° C. or higher and 65 ° C. or lower, more preferably 57 ° C. or higher and 60 ° C. or lower. It is.
The glass transition temperature is determined from a DSC curve obtained by differential scanning calorimetry (DSC), and more specifically described in the method for determining the glass transition temperature in JIS K 7121-1987 “Method for Measuring Plastic Transition Temperature”. Of “extrapolated glass transition start temperature”.

The weight average molecular weight of the styrene (meth) acrylic resin is, for example, from 30,000 to 200,000, preferably from 40,000 to 100,000, and more preferably from 50,000 to 80,000 in terms of storage stability.
The weight average molecular weight is measured by gel permeation chromatography (GPC). The molecular weight measurement by GPC is performed with a THF solvent using a Tosoh GPC / HLC-8120GPC as a measuring device and a Tosoh column / TSKgel SuperHM-M (15 cm). The weight average molecular weight is calculated from the measurement result using a molecular weight calibration curve prepared with a monodisperse polystyrene standard sample.

  Various polymerization methods (for example, solution polymerization, precipitation polymerization, suspension polymerization, bulk polymerization, emulsion polymerization, etc.) are applied to the styrene (meth) acrylic resin. For the polymerization reaction, known operations (for example, batch-wise, semi-continuous, continuous, etc.) are applied.

  The content of the binder resin is, for example, preferably 40% by weight to 95% by weight, more preferably 50% by weight to 90% by weight, and more preferably 60% by weight to 85% by weight with respect to the entire toner particles. Further preferred.

-Release agent-
Examples of mold release agents include hydrocarbon waxes; natural waxes such as carnauba wax, rice wax, and candelilla wax; synthetic or mineral / petroleum waxes such as montan wax; and ester waxes such as fatty acid esters and montanic acid esters. And so on. The release agent is not limited to this.

  Among these, as the release agent, hydrocarbon wax (wax having a hydrocarbon as a skeleton) is preferable. Hydrocarbon wax is suitable because it easily forms a release agent domain and easily oozes out on the surface of toner particles at the time of fixing.

The melting temperature of the release agent is preferably 50 ° C. or higher and 110 ° C. or lower, and more preferably 60 ° C. or higher and 100 ° C. or lower.
Note that the melting temperature is obtained from the DSC curve obtained by differential scanning calorimetry (DSC) according to “melting peak temperature” described in JIS K 7121-1987 “Method for measuring the melting temperature of plastics”. .

  The content of the release agent is, for example, preferably 1% by mass to 20% by mass and more preferably 5% by mass to 15% by mass with respect to the entire toner particles.

-Colorant-
Examples of the colorant include carbon black, chrome yellow, hansa yellow, benzidine yellow, sren yellow, quinoline yellow, pigment yellow, permanent orange GTR, pyrazolone orange, vulcan orange, watch young red, permanent red, brilliant carmine 3B, and brilliant. Carmine 6B, Dupont Oil Red, Pyrazolone Red, Resol Red, Rhodamine B Lake, Lake Red C, Pigment Red, Rose Bengal, Aniline Blue, Ultramarine Blue, Calco Oil Blue, Methylene Blue Chloride, Phthalocyanine Blue, Pigment Blue, Phthalocyanine Green, Various pigments such as malachite green oxalate, or acridine, xanthene, , Benzoquinone, azine, anthraquinone, thioindico, dioxazine, thiazine, azomethine, indico, phthalocyanine, aniline black, polymethine, triphenylmethane, diphenylmethane, thiazole, and other dyes Etc.
A colorant may be used individually by 1 type and may use 2 or more types together.

  As the colorant, a surface-treated colorant may be used as necessary, or it may be used in combination with a dispersant. A plurality of colorants may be used in combination.

  The content of the colorant is, for example, preferably 1% by mass or more and 30% by mass or less, and more preferably 3% by mass or more and 15% by mass or less with respect to the entire toner particles.

-Other additives-
Examples of other additives include known additives such as a magnetic material, a charge control agent, and inorganic powder. These additives are contained in the toner particles as internal additives.

-Toner particle characteristics-
The toner particles may be toner particles having a single layer structure, or toner particles having a so-called core / shell structure composed of a core (core particle) and a coating layer (shell layer) covering the core. May be.
Here, the core / shell structure toner particles include, for example, a core portion including a binder resin and, if necessary, other additives such as a colorant and a release agent, and a binder resin. It is good to be comprised with the comprised coating layer.

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

In addition, various average particle diameters and various particle size distribution indexes of the toner particles are measured using Coulter Multisizer II (manufactured by Beckman Coulter), and the electrolyte is measured using ISOTON-II (manufactured by Beckman Coulter). The
In the measurement, 0.5 mg to 50 mg of a measurement sample is added as a dispersant to 2 ml of a 5% aqueous solution of a surfactant (preferably sodium alkylbenzenesulfonate). This is added to 100 ml or more and 150 ml or less of the electrolytic solution.
The electrolyte in which the sample is suspended is dispersed for 1 minute with an ultrasonic disperser, and the particle size distribution of particles having a particle size in the range of 2 μm to 60 μm is obtained using a 100 μm aperture with a Coulter Multisizer II. taking measurement. The number of particles to be sampled is 50,000.
For the particle size range (channel) divided based on the measured particle size distribution, the cumulative distribution is drawn from the smaller diameter side to the volume and number, respectively, and the particle size to be 16% is the volume particle size D16v, the number particle size D16p, a particle size that is 50% cumulative is defined as a volume average particle size D50v, a cumulative number average particle size D50p, and a particle size that is 84% cumulative is defined as a volume particle size D84v and a number particle size D84p.
Using these, the volume particle size distribution index (GSDv) is calculated as (D84v / D16v) ^1/2 and the number particle size distribution index (GSDp) is calculated as (D84p / D16p) ^1/2 .

(External additive)
The external additive includes first silica particles and second silica particles. The external additive may include other external additives. That is, only the first silica particles and the second silica particles may be externally added to the toner particles, or the first silica particles and the second silica particles and other external additives may be externally added. Good.

-Silica particles-
Both the first silica particles and the second silica particles may be silica, that is, particles containing SiO ₂ as a main component, and may be crystalline or amorphous. Moreover, both the first silica particles and the second silica particles may be particles produced from a silicon compound such as water glass or alkoxysilane, or particles obtained by pulverizing quartz. Also good.
Specifically, both the first silica particles and the second silica particles include, for example, sol-gel silica particles, aqueous colloidal silica particles, alcoholic silica particles, fumed silica particles obtained by a gas phase method, and fused silica particles. Can be mentioned. Among these, as the first silica particles and the second silica particles, both sol-gel silica particles are preferable from the viewpoint of satisfying the following characteristics.

The average primary particle size Da (nm) of the first silica particles and the average primary particle size Db (nm) of the second silica particles satisfy the relationship of the following formulas (A1) to (A3).
Formula (A1): 80 ≦ Da ≦ 120
Formula (A2): 120 ≦ Db ≦ 200
Formula (A3): 15 ≦ Db−Da ≦ 120

  By setting the average primary particle size Da of the first silica particles on the small diameter side to 80 nm or more and 120 nm or less, the first silica particles are likely to be present on the convex portions of the toner particles. In addition, when the average primary particle diameter Db of the second silica particles on the large diameter side is set to 120 nm or more and 200 nm or less, the second silica particles roll on the toner particles and easily exist in the concave portions of the toner.

  By making the particle size difference between the average primary particle size Da (nm) of the first silica particles and the average primary particle size Db (nm) of the second silica particles 15 nm or more, the first silica particles and the second silica particles are Since the surface of the toner particles can be coated in a nearly uniform state, the generation of a color point when an image is formed with toner after storage in a high temperature and high humidity environment is suppressed.

The average primary particle size Da (nm) of the first silica particles and the average primary particle size Db (nm) of the second silica particles are the color points when an image is formed with toner after being stored in a high temperature and high humidity environment. From the point that generation | occurrence | production of is suppressed more, it is preferable to satisfy | fill the relationship of following formula (A1-2)-formula (A3-2).
Formula (A1-2): 80 ≦ Da ≦ 110
Formula (A2-2): 120 ≦ Db ≦ 180
Formula (A3-2): 20 ≦ Db−Da ≦ 100

The average primary particle size Da (nm) of the first silica particles and the average primary particle size Db (nm) of the second silica particles are the color points when an image is formed with toner after being stored in a high temperature and high humidity environment. From the point that generation | occurrence | production of is suppressed more, it is more preferable to satisfy | fill the relationship of following formula (A1-3)-formula (A3-3).
Formula (A1-3): 85 ≦ Da ≦ 100
Formula (A2-3): 120 ≦ Db ≦ 160
Formula (A3-3): 20 ≦ Db−Da ≦ 60

Here, the average primary particle diameter of the silica particles is measured by the following method.
The primary particles of the silica particles are observed with a scanning electron microscope SEM (Scanning Electron Microscope) device (manufactured by Hitachi, Ltd .: S-4100) to take an image, and this image is taken as an image analysis device (LUZEXIII, (stock) ) (Manufactured by Nireco), the area of each particle is measured by image analysis of primary particles, and the equivalent circle diameter is calculated from the area value. The calculation of the equivalent circle diameter is performed for 100 silica particles. The 50% diameter (D50) in the volume-based cumulative frequency of the obtained equivalent circle diameter is defined as the average primary particle diameter (average equivalent circle diameter D50) of the silica particles. Note that the magnification of the electron microscope is adjusted so that about 10 to 50 silica particles are captured in one field of view, and the equivalent circle diameter of the primary particles is obtained by observing a plurality of fields of view.

  The average circularity of the first silica particles and the second silica particles is not particularly limited. For example, the average circularity of the second silica particles is preferably 0.9 or more and 1.0 or less, and 0.92 or more and 0.00. It is preferable that it is 98 or less. The average circularity of the first silica particles and the second silica particles is preferably 0.9 or more and 1.0 or less, and preferably 0.92 or more and 0.98 or less.

  In particular, when the average circularity of the second silica particles is 0.9 or more and 1.0 or less, the large-diameter silica particles easily roll on the toner particles and easily move to the concave portions of the toner particles. Thereby, since the silica particles can be coated in a nearly uniform state of the toner particles, thermal aggregation after storage in a high temperature and high humidity environment is more easily suppressed. In addition, by setting the average circularity of the silica particles of the first silica particles and the second silica particles to 0.9 or more and 1.0 or less, both the silica particles have a shape close to a sphere. Thereby, since the fluidity of the toner is improved, it is considered that thermal aggregation after storage in a high temperature and high humidity environment is more easily suppressed.

Here, the average circularity of the silica particles is measured by the following method.
The circularity of the silica particles is obtained by observing primary particles after dispersing the silica particles in a resin particle main body (for example, polyester resin, weight average molecular weight Mw = 500,000) having a volume average particle size of 100 μm, using an SEM apparatus. From the plane image analysis of the obtained primary particles, it is obtained as “100 / SF2” calculated by the following formula.
Formula: Circularity (100 / SF2) = 4π × (A / I ² )
[In the formula, I represents the perimeter of the primary particles on the image, and A represents the projected area of the primary particles.
The average circularity of the silica particles is obtained as 50% circularity in the cumulative frequency of 100 primary particles obtained by the planar image analysis.

The particle size distribution index of the first silica particles and the second silica particles is preferably 1.05 or more and 1.25 or less. The particle size distribution index of the first silica particles and the second silica particles is preferably 1.05 or more and 1.2 or less, more preferably 1.05 or more and 1.15 or less.
When the particle size distribution index of the first silica particles and the second silica particles is in the range of 1.05 or more and 1.25 or less, the particle size distribution is sharp (sharp), so that the surface of the toner particles is coated in a nearly uniform state. obtain. Thereby, it is considered that the generation of a color point is more easily suppressed when an image is formed with toner after being stored in a high temperature and high humidity environment.

Here, the particle size distribution index of the silica particles is measured by the following method.
The primary particles of the silica particles are observed with a scanning electron microscope SEM (Scanning Electron Microscope) device (manufactured by Hitachi, Ltd .: S-4100) to take an image, and this image is taken as an image analysis device (LUZEXIII, (stock) ) (Manufactured by Nireco), the area of each particle is measured by image analysis of primary particles, and the equivalent circle diameter is calculated from the area value. The calculation of the equivalent circle diameter is performed for 100 silica particles. Then, the 16% diameter (D16) and the 84% diameter (D84) in the volume-based cumulative frequency of the obtained equivalent circle diameter are obtained. The square root obtained by dividing the obtained 84% diameter (D84) by the 16% diameter (D16) is defined as a particle size distribution index (= (D84 / D16) ^1/2 ). Note that the magnification of the electron microscope is adjusted so that about 10 to 50 silica particles are captured in one field of view, and the equivalent circle diameter of the primary particles is obtained by observing a plurality of fields of view.

The surfaces of the first silica particles and the second silica particles are preferably subjected to a hydrophobic treatment. The hydrophobic treatment is performed, for example, by immersing inorganic particles in a hydrophobic treatment agent. The hydrophobizing agent is not particularly limited, and examples thereof include known organosilicon compounds having an alkyl group (for example, a methyl group, an ethyl group, a propyl group, a butyl group). Specifically, for example, a silazane compound ( Examples thereof include silane coupling agents such as silane compounds such as methyltrimethoxysilane, dimethyldimethoxysilane, trimethylchlorosilane, and trimethylmethoxysilane; hexamethyldisilazane; tetramethyldisilazane, and the like. Examples of the hydrophobizing agent include silicone oil, titanate coupling agents, and aluminum coupling agents. These may be used individually by 1 type and may use 2 or more types together.
The amount of the hydrophobizing agent is usually, for example, from 1 part by mass to 200 parts by mass with respect to 100 parts by mass of silica particles.

  The total content of the first silica particles and the second silica particles (total external addition amount) is preferably 0.5% by mass or more and 3% by mass or less, and preferably 1% by mass or more and 3% by mass or less with respect to the toner particles. More preferably, the content is 1% by mass or more and 2% by mass or less.

  Ratio of external addition amount (content) of first silica particles to external addition amount (content) of second silica particles (mass ratio: external addition amount of first silica particles / external addition amount of second silica particles) Is preferably 25/75 or more and 75/25 or less, more preferably 35/65 or more and 70/30 or less, and still more preferably 40/60 or more and 60/40 or less.

-Other external additives-
Examples of other external additives include inorganic particles other than the first silica particles and the second silica particles.
Examples of other inorganic particles include silica, aluminum oxide (alumina), titanium oxide, barium titanate, magnesium titanate, calcium titanate, strontium titanate, zinc oxide, chromium oxide, cerium oxide, magnesium oxide, zirconium oxide, Examples of the particles include silicon carbide and silicon nitride.

The surface of other inorganic particles is preferably subjected to a hydrophobic treatment. The hydrophobic treatment is performed, for example, by immersing inorganic particles in a hydrophobic treatment agent. The hydrophobizing agent is not particularly limited, and examples thereof include silane coupling agents, silicone oils, titanate coupling agents, and aluminum coupling agents. These may be used individually by 1 type and may use 2 or more types together.
The amount of the hydrophobizing agent is usually 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of other inorganic particles, for example.

  Other external additives include resin particles (polystyrene, polymethyl methacrylate (PMMA), resin particles such as melamine resin), cleaning agents (for example, metal salts of higher fatty acids represented by zinc stearate, fluorine-based high additives, etc. And molecular weight particles).

  The external addition amount (content) of other external additives is preferably 0.05% by mass or more and 5.0% by mass or less, and more preferably 0.5% by mass or more and 3.0% by mass with respect to the toner particles. The following is more preferable.

(Toner production method)
Next, a toner manufacturing method according to this embodiment will be described.
The toner according to the exemplary embodiment can be obtained by externally adding an external additive to the toner particles after the toner particles are manufactured.

The toner particles may be produced by any of a dry production method (for example, a kneading and pulverizing method) and a wet production method (for example, an aggregation coalescence method, a suspension polymerization method, a dissolution suspension method, etc.). The production method of the toner particles is not particularly limited, and a known production method is adopted.
Among these, it is preferable to obtain toner particles by an aggregation and coalescence method.

In particular, when producing toner (toner particles) satisfying the distribution characteristics of the uneven distribution degree B of the release agent domain described above, the toner particles are preferably produced by the following aggregation and coalescence method.
In the following aggregation and coalescence method, a method for producing a toner (toner particles) including a colorant will be described. The colorant is an additive contained in the toner particles as necessary.

Specifically, a step of preparing each dispersion (dispersion preparation step),
A first resin particle dispersion in which first resin particles to be a binder resin are dispersed and a colorant particle dispersion in which colorant particles (hereinafter also referred to as “colorant particles”) are mixed are obtained. A step of aggregating each particle in the dispersed liquid to form first agglomerated particles (first agglomerated particle forming step);
After obtaining the first agglomerated particle dispersion in which the first agglomerated particles are dispersed, the mixture in which the second resin particles to become the binder resin and the release agent particles (hereinafter also referred to as “release agent particles”) are dispersed. The dispersion is sequentially added to the first aggregated particle dispersion while gradually increasing the concentration of the release agent particles in the mixed dispersion, and second resin particles and release agent particles are further added to the surface of the first aggregated particles. A step of agglomerating to form second agglomerated particles (second agglomerated particle forming step);
After obtaining the second aggregated particle dispersion in which the second aggregated particles are dispersed, the second aggregated particle dispersion and the third resin particle dispersion in which the third resin particles serving as the binder resin are further dispersed Mixing and aggregating so that the third resin particles further adhere to the surface of the second aggregated particles to form third aggregated particles (third aggregated particle forming step);
Heating the third agglomerated particle dispersion in which the third agglomerated particles are dispersed, fusing and coalescing the third agglomerated particles to form toner particles (fusing and coalescing step);
Through this process, it is preferable to produce toner particles.

  The method for producing toner particles is not limited to the above. For example, the resin particle dispersion and the colorant particle dispersion are mixed, and the particles are aggregated in the obtained mixed dispersion. Next, in the aggregation process, the release agent particle dispersion is added to the mixed dispersion while gradually increasing the addition rate or increasing the concentration of the release agent particles, and further the aggregation of each particle is advanced. To form agglomerated particles. Then, the aggregated particles may be fused and combined to form toner particles.

  Details of each step will be described below.

-Each dispersion preparation process-
First, it prepares with each dispersion liquid used by the aggregation coalescence method. Specifically, the first resin particle dispersion in which the first resin particles to be the binder resin are dispersed, the colorant particle dispersion in which the colorant particles are dispersed, and the second resin particles to be the binder resin are dispersed. The second resin particle dispersion, the third resin particle dispersion in which the third resin particles as the binder resin are dispersed, and the release agent particle dispersion in which the release agent particles are dispersed are prepared.
In each dispersion preparation step, the first resin particles, the second resin particles, and the third resin particles are referred to as “resin particles”.

  Here, the resin particle dispersion is prepared, for example, by dispersing resin particles in a dispersion medium using a surfactant.

Examples of the dispersion medium used for the resin particle dispersion include an aqueous medium.
Examples of the aqueous medium include water such as distilled water and ion exchange water, and alcohols. These may be used individually by 1 type and may use 2 or more types together.

Examples of the surfactant include anionic surfactants such as sulfate ester, sulfonate, phosphate, and soap; cationic surfactants such as amine salt type and quaternary ammonium salt type; polyethylene glycol And nonionic surfactants such as polyphenols, alkylphenol ethylene oxide adducts, and polyhydric alcohols. Among these, an anionic surfactant and a cationic surfactant are particularly mentioned. The nonionic surfactant may be used in combination with an anionic surfactant or a cationic surfactant.
Surfactant may be used individually by 1 type and may use 2 or more types together.

Examples of the method for dispersing the resin particles in the dispersion medium in the resin particle dispersion include a general dispersion method such as a rotary shear homogenizer, a ball mill having media, a sand mill, and a dyno mill. Depending on the type of resin particles, the resin particles may be dispersed in the resin particle dispersion using, for example, a phase inversion emulsification method.
The phase inversion emulsification method is a method in which a resin to be dispersed is dissolved in a hydrophobic organic solvent in which the resin is soluble, and a base is added to the organic continuous phase (O phase) to neutralize the aqueous medium. (W phase) is added to convert the resin from W / O to O / W (so-called phase inversion) to form a discontinuous phase and disperse the resin in an aqueous medium in the form of particles. It is.

The volume average particle size of the resin particles dispersed in the resin particle dispersion is, for example, preferably 0.01 μm to 1 μm, more preferably 0.08 μm to 0.8 μm, and further preferably 0.1 μm to 0.6 μm. preferable.
In addition, the volume average particle diameter of the resin particles is divided into particle size ranges (channels) using a particle size distribution obtained by measurement with a laser diffraction particle size distribution measuring apparatus (for example, LA-700 manufactured by Horiba, Ltd.). On the other hand, the cumulative distribution is drawn from the small diameter side with respect to the volume, and the particle diameter that is 50% cumulative with respect to all particles is measured as the volume average particle diameter D50v. The volume average particle size of particles in other dispersions is also measured in the same manner.

  As content of the resin particle contained in a resin particle dispersion liquid, 5 to 50 mass% is preferable, for example, and 10 to 40 mass% is more preferable.

  For example, a colorant particle dispersion and a release agent particle dispersion are also prepared in the same manner as the resin particle dispersion. In other words, regarding the volume average particle diameter of the particles in the resin particle dispersion, the dispersion medium, the dispersion method, and the content of the particles, the colorant particles dispersed in the colorant particle dispersion and the release agent particle dispersion The same applies to the release agent particles to be dispersed.

-First aggregated particle forming step-
Next, the first resin particle dispersion and the colorant particle dispersion are mixed.
Then, in this mixed dispersion, the first resin particles and the colorant particles are heteroaggregated to form first aggregated particles including the first resin particles and the colorant particles.

Specifically, for example, the flocculant is added to the mixed dispersion, and the pH of the mixed dispersion is adjusted to acidic (for example, the pH is 2 or more and 5 or less), and a dispersion stabilizer is added as necessary. Particles heated to the glass transition temperature of the first resin particles (specifically, for example, the glass transition temperature of the first resin particles −30 ° C. or more and the glass transition temperature −10 ° C. or less) and dispersed in the mixed dispersion liquid Are aggregated to form first aggregated particles.
In the first agglomerated particle forming step, for example, the flocculant is added at room temperature (for example, 25 ° C.) while stirring the mixed dispersion with a rotary shearing homogenizer, and the pH of the mixed dispersion is acidic (for example, pH is 2 or more). 5 or less) and, if necessary, after adding a dispersion stabilizer, the heating may be performed.

Examples of the flocculant include a surfactant having a polarity opposite to that of the surfactant used as the dispersant added to the mixed dispersion, an inorganic metal salt, and a divalent or higher-valent metal complex. In particular, when a metal complex is used as the flocculant, the amount of the surfactant used is reduced, and the charging characteristics are improved.
If necessary, an additive that forms a complex or a similar bond with the metal ion of the flocculant may be used. As this additive, a chelating agent is preferably used.

Examples of inorganic metal salts include metal salts such as calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate, and inorganic substances such as polyaluminum chloride, polyaluminum hydroxide, and calcium polysulfide. Examples thereof include metal salt polymers.
A water-soluble chelating agent may be used as the chelating agent. Examples of the chelating agent include oxycarboxylic acids such as tartaric acid, citric acid, and gluconic acid, iminodiacid (IDA), nitrilotriacetic acid (NTA), ethylenediaminetetraacetic acid (EDTA), and the like.
The addition amount of the chelating agent is preferably 0.01 parts by mass or more and 5.0 parts by mass or less, and more preferably 0.1 parts by mass or more and less than 3.0 parts by mass with respect to 100 parts by mass of the first resin particles. .

-Second aggregated particle forming step-
Next, after obtaining the first agglomerated particle dispersion in which the first agglomerated particles are dispersed, the mixed dispersion in which the second resin particles and the releasing agent particles are dispersed is used as the release agent particles in the mixed dispersion. Sequentially added to the first aggregated particle dispersion while increasing the concentration.
The second resin particles may be the same type as the first resin particles or different types.

  Then, in the dispersion liquid in which the first aggregated particles, the second resin particles, and the release agent particles are dispersed, the second resin particles and the release agent particles are aggregated on the surface of the first aggregated particles. Specifically, for example, in the first aggregated particle forming step, when the first aggregated particles reach the target particle size, the concentration of the release agent particles is gradually increased in the first aggregated particle dispersion, A mixed dispersion in which the second resin particles and the release agent particles are dispersed is added, and the dispersion is heated at a temperature equal to or lower than the glass transition temperature of the second resin particles.

  Through this step, aggregated particles in which the second resin particles and the release agent particles are attached to the surface of the first aggregated particles are formed. That is, the second aggregated particles in which the aggregates of the second resin particles and the release agent particles are attached to the surface of the first aggregated particles are formed. At this time, the mixed dispersion in which the second resin particles and the release agent particles are dispersed is sequentially added to the first aggregated particle dispersion while gradually increasing the concentration of the release agent particles in the mixed dispersion. On the surface of the first aggregated particles, the concentration (existence ratio) of the release agent particles gradually increases toward the outside in the particle diameter direction, and the aggregates of the second resin particles and the release agent particles adhere.

  Here, as a method for adding the mixed dispersion, it is preferable to use a power feed addition method. By utilizing this power feed addition method, the mixed dispersion can be added to the first aggregated particle dispersion while gradually increasing the concentration of the release agent particles in the mixed dispersion.

  Hereinafter, a method for adding a mixed dispersion using a power feed addition method will be described with reference to the drawings.

  FIG. 3 shows an apparatus used for the power feed addition method. In FIG. 3, 311 indicates the first aggregated particle dispersion, 312 indicates the second resin particle dispersion, and 313 indicates the release agent particle dispersion.

  The apparatus shown in FIG. 3 contains a first storage tank 321 in which first aggregated particles are dispersed and contains a first aggregated particle dispersion, and a second resin particle dispersion in which second resin particles are dispersed. The second storage tank 322 and the third storage tank 323 that stores the release agent particle dispersion in which the release agent particles are dispersed.

The first storage tank 321 and the second storage tank 322 are connected by a first liquid feeding pipe 331. A first liquid feed pump 341 is interposed in the middle of the path of the first liquid feed pipe 331. By driving the first liquid feed pump 341, the dispersion liquid stored in the second storage tank 322 is sent to the dispersion liquid stored in the first storage tank 321 through the first liquid supply pipe 331.
A first stirring device 351 is disposed in the first storage tank 321. When the dispersion liquid stored in the second storage tank 322 is fed to the dispersion liquid stored in the first storage tank 321 by driving the first stirring device 351, each dispersion liquid is stirred and Mixed.

The second storage tank 322 and the third storage tank 323 are connected by a second liquid feeding pipe 332. In the middle of the path of the second liquid feeding pipe 332, a second liquid feeding pump 342 is interposed. By driving the second liquid feed pump 342, the dispersion liquid stored in the third storage tank 323 is sent to the dispersion liquid stored in the second storage tank 322 through the second liquid supply pipe 332.
A second stirring device 352 is disposed in the second storage tank 322. When the dispersion liquid stored in the third storage tank 323 is fed to the dispersion liquid stored in the second storage tank 322 by driving the second stirring device 352, each dispersion liquid is stirred and Mixed.

  In the apparatus shown in FIG. 3, first, a first aggregated particle forming step is performed in the first storage tank 321 to produce a first aggregated particle dispersion, and the first aggregated particle dispersion is added to the first storage tank 321. Accommodate. Note that the first aggregated particle dispersion may be stored in the first storage tank 321 after the first aggregated particle forming step is performed in another tank to produce the first aggregated particle dispersion.

In this state, the first liquid pump 341 and the second liquid pump 342 are driven. By this driving, the second resin particle dispersion liquid stored in the second storage tank 322 is fed to the first aggregated particle dispersion liquid stored in the first storage tank 321. Each dispersion is stirred and mixed in the first storage tank 321 by driving the first stirring device 351.
On the other hand, the release agent particle dispersion liquid stored in the third storage tank 323 is fed to the second resin particle dispersion liquid stored in the second storage tank 322. Then, each dispersion liquid is stirred and mixed in the second storage tank 322 by driving the second stirring device 352.

  At this time, the release agent particle dispersion is sequentially fed to the second resin particle dispersion stored in the second storage tank 322, and the concentration of the release agent particles gradually increases. Therefore, the second storage tank 322 stores the mixed dispersion liquid in which the second resin particles and the release agent particles are dispersed, and the mixed dispersion liquid is stored in the first storage tank 321. It is sent to one aggregated particle dispersion. The mixed dispersion is fed continuously while the concentration of the release agent particle dispersion in the mixed dispersion is increased.

Thus, by using the power feed addition method, the mixed dispersion liquid in which the second resin particles and the release agent particles are dispersed while gradually increasing the concentration of the release agent particles in the first aggregated particle dispersion liquid. Can be added.
In the power feed addition method, the distribution characteristics of the release agent domains of the toner are adjusted by adjusting the liquid feed start timing and the liquid feed speed of the respective dispersions stored in the second storage tank 322 and the third storage tank 323. Is adjusted. Further, in the power feed addition method, the distribution of the toner release agent domain can also be adjusted by adjusting the liquid feeding speed during the liquid feeding of the respective dispersions stored in the second storage tank 322 and the third storage tank 323. Characteristics are adjusted.

  Specifically, for example, the mode of the distribution of the degree of uneven distribution B of the release agent domain is adjusted by the timing when the release agent particle dispersion liquid has been fed from the third storage tank 323 to the second storage tank 322. The More specifically, for example, before the liquid feeding from the second storage tank 322 to the first storage tank 321 is completed, the release agent particle dispersion liquid is fed from the third storage tank 323 to the second storage tank 322. When is finished, the concentration of the release agent particles in the mixed dispersion in the second storage tank 322 does not increase beyond that point. Thereby, the mode value of the distribution of the uneven distribution degree B of the release agent domain becomes small.

  Further, for example, the skewness of the distribution of the uneven distribution degree B of the release agent domain is determined by the timing of sending each dispersion liquid from the second storage tank 322 and the third storage tank 323 and the first storage tank from the second storage tank 322. It is adjusted by the liquid feeding speed at which the dispersion liquid is fed to 321. More specifically, for example, the liquid feed start timing of the release agent particle dispersion from the third storage tank 323 and the liquid feed start timing of the dispersion liquid from the second storage tank 322 are advanced, and the second storage tank 322 When the liquid feeding speed of the dispersion liquid is reduced, the release agent particles are arranged from the inner side to the outer side of the particles in the formed aggregated particles. Thereby, the skewness of the distribution of the uneven distribution degree B of the release agent domain is increased.

  In addition, the power feed addition method demonstrated above is not necessarily limited to the said method. For example, 1) Separately, a storage tank in which the second resin particle dispersion is stored, and a storage tank in which the second resin particles and the release agent particle dispersion are dispersed are provided, and the liquid feeding speed is changed. A method of feeding each dispersion liquid from each storage tank to the first storage tank 321, a separate storage tank containing the release agent particle dispersion liquid, and mixing in which the second resin particles and the release agent particle dispersion liquid are dispersed Various methods may be employed, such as a method of providing a storage tank containing the dispersion liquid and feeding each dispersion liquid from each storage tank to the first storage tank 321 while changing the liquid feeding speed.

  As described above, the second aggregated particles aggregated so that the second resin particles and the release agent particles adhere to the surface of the first aggregated particles are obtained.

-Third aggregated particle forming step-
Next, after obtaining the second aggregated particle dispersion in which the second aggregated particles are dispersed, the second aggregated particle dispersion, and the third resin particle dispersion in which the third resin particles serving as the binder resin are dispersed, , Are further mixed.
In addition, the 3rd resin particle may be the same kind as the 1st or 2nd resin particle, and a different kind may be sufficient as it.

Then, the third resin particles are aggregated on the surface of the second aggregated particles in the dispersion liquid in which the second aggregated particles and the third resin particles are dispersed. Specifically, for example, in the second aggregated particle forming step, when the second aggregated particle reaches a target particle size, the third resin particle dispersion is added to the second aggregated particle dispersion. The dispersion is heated below the glass transition temperature of the third resin particles.
Then, the progress of aggregation is stopped by adjusting the pH of the dispersion to a range of, for example, about 6.5 to 8.5.

-Fusion / unification process-
Next, with respect to the third aggregated particle dispersion in which the third aggregated particles are dispersed, for example, the glass transition temperature of the first, second, and third resin particles is higher than (for example, the first, second, and third resin particles). And a third aggregated particle is fused and united to form toner particles.

Through the above steps, toner particles are obtained.
In the toner particles (toner) obtained by the above steps, the distribution characteristic of the degree of uneven distribution B of the release agent domain falls within the above range.

Here, after completion of the fusion / unification process, toner particles formed in the solution are dried through a known washing process, solid-liquid separation process, and drying process to obtain toner particles.
In the washing step, it is preferable to sufficiently carry out substitution washing with ion-exchanged water from the viewpoint of chargeability. The solid-liquid separation step is not particularly limited, but suction filtration, pressure filtration, etc. are preferably performed from the viewpoint of productivity. In addition, the drying process is not particularly limited, but from the viewpoint of productivity, freeze drying, airflow drying, fluidized drying, vibration fluidized drying, or the like is preferably performed.

  The toner according to the exemplary embodiment is manufactured, for example, by adding an external additive to the obtained dry toner particles and mixing them. Mixing may be performed by, for example, a V blender, a Henschel mixer, a Laedige mixer, or the like. Further, if necessary, coarse toner particles may be removed using a vibration sieving machine, a wind sieving machine, or the like.

<Electrostatic image developer>
The electrostatic charge image developer according to the exemplary embodiment includes at least the toner according to the exemplary embodiment.
The electrostatic image developer according to this embodiment may be a one-component developer including only the toner according to this embodiment, or may be a two-component developer mixed with the toner and a carrier.

There is no restriction | limiting in particular as a carrier, A well-known carrier is mentioned. As a carrier, for example, a coated carrier in which the surface of a core made of magnetic powder is coated with a coating resin; a magnetic powder dispersion type carrier in which magnetic powder is dispersed and mixed in a matrix resin; a porous magnetic powder is impregnated with a resin Resin impregnated type carriers; and the like.
Note that the magnetic powder-dispersed carrier and the resin-impregnated carrier may be a carrier in which the constituent particles of the carrier are used as a core material and coated with a coating resin.

  Examples of the magnetic powder include magnetic metals such as iron, nickel, and cobalt, and magnetic oxides such as ferrite and magnetite.

Examples of the coating resin and the matrix resin include polyethylene, polypropylene, polystyrene, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl ether, polyvinyl ketone, vinyl chloride-vinyl acetate copolymer, styrene-acrylic acid ester. Examples thereof include a straight silicone resin comprising a copolymer, an organosiloxane bond, or a modified product thereof, a fluororesin, a polyester, a polycarbonate, a phenol resin, and an epoxy resin.
The coating resin and matrix resin may contain other additives such as conductive particles.
Examples of the conductive particles include particles of metals such as gold, silver, and copper, carbon black, titanium oxide, zinc oxide, tin oxide, barium sulfate, aluminum borate, and potassium titanate.

Here, in order to coat the surface of the core material with the coating resin, a method of coating with a coating layer forming solution obtained by dissolving the coating resin and, if necessary, various additives in an appropriate solvent may be mentioned. The solvent is not particularly limited, and may be selected in consideration of the coating resin to be used, coating suitability, and the like.
Specific resin coating methods include a dipping method in which the core material is immersed in the coating layer forming solution, a spray method in which the coating layer forming solution is sprayed on the surface of the core material, and a state in which the core material is suspended by flowing air. Examples thereof include a fluidized bed method in which a coating layer forming solution is sprayed, a kneader coater method in which a carrier core material and a coating layer forming solution are mixed in a kneader coater, and the solvent is removed.

  The mixing ratio (mass ratio) of the toner and the carrier in the two-component developer is preferably toner: carrier = 1: 100 to 30: 100, and more preferably 3: 100 to 20: 100.

<Image Forming Apparatus / Image Forming Method>
The image forming apparatus / image forming method according to the present embodiment will be described.
The image forming apparatus according to the present embodiment includes an image carrier, a charging unit that charges the surface of the image carrier, an electrostatic image forming unit that forms an electrostatic image on the surface of the charged image carrier, and an electrostatic charge. Development means for containing an image developer and developing the electrostatic image formed on the surface of the image carrier as a toner image with the electrostatic image developer, and the toner image formed on the surface of the image carrier as a recording medium Transfer means for transferring to the surface of the recording medium, and fixing means for fixing the toner image transferred to the surface of the recording medium. The electrostatic charge image developer according to this embodiment is applied as the electrostatic charge image developer.

  In the image forming apparatus according to this embodiment, a charging process for charging the surface of the image carrier, an electrostatic charge image forming process for forming an electrostatic image on the surface of the charged image carrier, and an electrostatic charge according to this embodiment. A developing step of developing an electrostatic charge image formed on the surface of the image carrier as a toner image with an image developer; a transfer step of transferring the toner image formed on the surface of the image carrier to the surface of the recording medium; An image forming method (an image forming method according to the present embodiment) including a fixing step of fixing the toner image transferred onto the surface of the recording medium is performed.

The image forming apparatus according to the present embodiment is a direct transfer type apparatus that directly transfers a toner image formed on the surface of an image carrier to a recording medium; the toner image formed on the surface of the image carrier is transferred to an intermediate transfer member An intermediate transfer type apparatus that primarily transfers the toner image transferred to the surface of the intermediate transfer body and then secondary transfer the toner image to the surface of the recording medium; after the toner image is transferred, the surface of the image carrier before charging is cleaned. An apparatus provided with a cleaning unit; a known image forming apparatus such as an apparatus provided with a charge removing unit that discharges the surface of an image holding member by irradiating a discharge light after charging a toner image and before charging is applied.
In the case of an intermediate transfer type apparatus, the transfer means includes, for example, an intermediate transfer body on which a toner image is transferred to the surface, and a primary transfer that primarily transfers the toner image formed on the surface of the image holding body to the surface of the intermediate transfer body. And a secondary transfer unit that secondarily transfers the toner image transferred onto the surface of the intermediate transfer member onto the surface of the recording medium.

  In the image forming apparatus according to the present embodiment, for example, the part including the developing unit may have a cartridge structure (process cartridge) that is detachable from the image forming apparatus. As the process cartridge, for example, a process cartridge including a developing unit containing the electrostatic charge image developer according to the present embodiment is preferably used.

  Hereinafter, an example of the image forming apparatus according to the present embodiment will be described, but the present invention is not limited thereto. In addition, the main part shown to a figure is demonstrated and the description is abbreviate | omitted about others.

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to the present embodiment.
The image forming apparatus shown in FIG. 1 is a first to first electrophotographic method that outputs yellow (Y), magenta (M), cyan (C), and black (K) images based on color-separated image data. Fourth image forming units 10Y, 10M, 10C, and 10K (image forming means) are provided. These image forming units (hereinafter sometimes simply referred to as “units”) 10Y, 10M, 10C, and 10K are arranged in parallel at a predetermined distance from each other in the horizontal direction. The units 10Y, 10M, 10C, and 10K may be process cartridges that are detachable from the image forming apparatus.

Above each of the units 10Y, 10M, 10C, and 10K, an intermediate transfer belt 20 as an intermediate transfer member is extended through each unit. The intermediate transfer belt 20 is provided by being wound around a drive roll 22 and a support roll 24 that are in contact with the inner surface of the intermediate transfer belt 20 that are spaced apart from each other in the left to right direction in the drawing. The vehicle travels in the direction toward the unit 10K. The support roll 24 is applied with a force in a direction away from the drive roll 22 by a spring or the like (not shown), and tension is applied to the intermediate transfer belt 20 wound around the support roll 24. An intermediate transfer member cleaning device 30 is provided on the side of the image carrier of the intermediate transfer belt 20 so as to face the drive roll 22.
Further, each of the developing devices (developing means) 4Y, 4M, 4C, and 4K of the units 10Y, 10M, 10C, and 10K has yellow, magenta, cyan, and black contained in the toner cartridges 8Y, 8M, 8C, and 8K. The toner including the four color toners is supplied.

  Since the first to fourth units 10Y, 10M, 10C, and 10K have the same configuration, here, the first unit that forms a yellow image disposed on the upstream side in the intermediate transfer belt traveling direction. 10Y will be described as a representative. It should be noted that reference numerals with magenta (M), cyan (C), and black (K) are attached to the same parts as those of the first unit 10Y instead of yellow (Y). Description of the units 10M, 10C, and 10K will be omitted.

The first unit 10Y includes a photoreceptor 1Y that functions as an image holding member. Around the photoreceptor 1Y, a charging roll (an example of a charging unit) 2Y that charges the surface of the photoreceptor 1Y to a predetermined potential, and the charged surface is exposed by a laser beam 3Y based on the color-separated image signal. Then, an exposure device (an example of an electrostatic image forming unit) 3 that forms an electrostatic image, and a developing device (an example of a developing unit) 4Y that develops the electrostatic image by supplying toner charged to the electrostatic image, developed A primary transfer roll 5Y (an example of a primary transfer unit) that transfers a toner image onto the intermediate transfer belt 20, and a photoconductor cleaning device (an example of a cleaning unit) 6Y that removes toner remaining on the surface of the photoconductor 1Y after the primary transfer. Are arranged in order.
The primary transfer roll 5Y is disposed inside the intermediate transfer belt 20, and is provided at a position facing the photoreceptor 1Y. Further, a bias power source (not shown) for applying a primary transfer bias is connected to each of the primary transfer rolls 5Y, 5M, 5C, and 5K. Each bias power source varies the transfer bias applied to each primary transfer roll under the control of a control unit (not shown).

Hereinafter, an operation of forming a yellow image in the first unit 10Y will be described.
First, prior to operation, the surface of the photoreceptor 1Y is charged to a potential of −600V to −800V by the charging roll 2Y.
The photoreceptor 1Y is formed by laminating a photosensitive layer on a conductive substrate (for example, volume resistivity at 20 ° C .: 1 × 10 ⁻⁶ Ωcm or less). This photosensitive layer usually has a high resistance (general resin resistance), but has a property that the specific resistance of the portion irradiated with the laser beam changes when irradiated with the laser beam 3Y. Therefore, a laser beam 3Y is output to the surface of the charged photoreceptor 1Y via the exposure device 3 in accordance with yellow image data sent from a control unit (not shown). The laser beam 3Y is applied to the photosensitive layer on the surface of the photoreceptor 1Y, whereby an electrostatic charge image having a yellow image pattern is formed on the surface of the photoreceptor 1Y.

The electrostatic charge image is an image formed on the surface of the photoreceptor 1Y by charging, and the specific resistance of the irradiated portion of the photosensitive layer is lowered by the laser beam 3Y, and the charged charge on the surface of the photoreceptor 1Y flows. On the other hand, this is a so-called negative latent image formed by the charge remaining in the portion not irradiated with the laser beam 3Y.
The electrostatic charge image formed on the photoreceptor 1Y is rotated to a predetermined development position as the photoreceptor 1Y travels. At this development position, the electrostatic charge image on the photoreceptor 1Y is visualized (developed image) as a toner image by the developing device 4Y.

  In the developing device 4Y, for example, an electrostatic charge image developer containing at least yellow toner and a carrier is accommodated. The yellow toner is triboelectrically charged by being agitated inside the developing device 4Y, and has a charge of the same polarity (negative polarity) as the charged electric charge on the photoreceptor 1Y, and has a developer roll (a developer holding member). Example) is held on. As the surface of the photoreceptor 1Y passes through the developing device 4Y, the yellow toner is electrostatically attached to the latent image portion on the surface of the photoreceptor 1Y, and the latent image is developed with the yellow toner. . The photoreceptor 1Y on which the yellow toner image is formed continues to run at a predetermined speed, and the toner image developed on the photoreceptor 1Y is conveyed to a predetermined primary transfer position.

When the yellow toner image on the photoreceptor 1Y is conveyed to the primary transfer, a primary transfer bias is applied to the primary transfer roll 5Y, and an electrostatic force from the photoreceptor 1Y toward the primary transfer roll 5Y is applied to the toner image, so that the photoreceptor is exposed. The toner image on 1Y is transferred onto the intermediate transfer belt 20. The transfer bias applied at this time has a (+) polarity opposite to the polarity (−) of the toner, and is controlled to +10 μA by the control unit (not shown) in the first unit 10Y, for example.
On the other hand, the toner remaining on the photoreceptor 1Y is removed and collected by the photoreceptor cleaning device 6Y.

Further, the primary transfer bias applied to the primary transfer rolls 5M, 5C, and 5K after the second unit 10M is also controlled in accordance with the first unit.
Thus, the intermediate transfer belt 20 onto which the yellow toner image has been transferred by the first unit 10Y is sequentially conveyed through the second to fourth units 10M, 10C, and 10K, and the toner images of the respective colors are superimposed and transferred in a multiple manner. The

  The intermediate transfer belt 20 on which the four color toner images are transferred in multiple ways through the first to fourth units is disposed on the image transfer surface side of the intermediate transfer belt 20, the support roll 24 in contact with the inner surface of the intermediate transfer belt 20. The secondary transfer roll (an example of a secondary transfer unit) 26 is formed to a secondary transfer portion configured. On the other hand, a recording paper (an example of a recording medium) P is fed at a predetermined timing into a gap where the secondary transfer roll 26 and the intermediate transfer belt 20 are in contact via a supply mechanism, and the secondary transfer bias is supplied to the support roll. 24. The transfer bias applied at this time is a (−) polarity that is the same polarity as the polarity (−) of the toner, and an electrostatic force from the intermediate transfer belt 20 toward the recording paper P is applied to the toner image, so The toner image is transferred onto the recording paper P. The secondary transfer bias at this time is determined according to the resistance detected by a resistance detection means (not shown) for detecting the resistance of the secondary transfer portion, and is voltage-controlled.

  Thereafter, the recording paper P is fed into the pressure contact portions (nip portions) of a pair of fixing rolls in a fixing device (an example of a fixing unit) 28, and the toner image is fixed on the recording paper P to form a fixed image.

Examples of the recording paper P to which the toner image is transferred include plain paper used in electrophotographic copying machines, printers, and the like. In addition to the recording paper P, the recording medium may be an OHP sheet.
In order to further improve the smoothness of the image surface after fixing, the surface of the recording paper P is also preferably smooth. For example, coated paper with the surface of plain paper coated with resin, art paper for printing, etc. are preferably used. Is done.

  The recording paper P on which the color image has been fixed is carried out toward the discharge unit, and a series of color image forming operations is completed.

<Process cartridge / toner cartridge>
The process cartridge according to this embodiment will be described.
The process cartridge according to the present embodiment accommodates the electrostatic charge image developer according to the present embodiment, and develops the electrostatic charge image formed on the surface of the image carrier as a toner image by the electrostatic charge image developer. And a process cartridge that can be attached to and detached from the image forming apparatus.

  Note that the process cartridge according to the present embodiment is not limited to the above-described configuration, and other means such as a developing device and other units such as an image carrier, a charging unit, an electrostatic charge image forming unit, and a transfer unit, if necessary. And at least one selected from the above.

  Hereinafter, an example of the process cartridge according to the present embodiment will be shown, but the present invention is not limited to this. In addition, the main part shown to a figure is demonstrated and the description is abbreviate | omitted about others.

FIG. 2 is a schematic configuration diagram showing a process cartridge according to the present embodiment.
The process cartridge 200 shown in FIG. 2 is provided around the photoconductor 107 and the photoconductor 107 by, for example, a housing 117 provided with an attachment rail 116 and an opening 118 for exposure. A charging roller 108 (an example of a charging unit), a developing device 111 (an example of a developing unit), and a photoconductor cleaning device 113 (an example of a cleaning unit) are integrally combined and held to form a cartridge. Yes.
In FIG. 2, 109 is an exposure device (an example of an electrostatic charge image forming unit), 112 is a transfer device (an example of a transfer unit), 115 is a fixing device (an example of a fixing unit), and 300 is a recording paper (a recording medium). An example).

Next, the toner cartridge according to this embodiment will be described.
The toner cartridge according to the present exemplary embodiment is a toner cartridge that accommodates the toner according to the present exemplary embodiment and is detachable from the image forming apparatus. The toner cartridge contains toner for replenishment to be supplied to the developing means provided in the image forming apparatus.

  The image forming apparatus shown in FIG. 1 is an image forming apparatus having a configuration in which toner cartridges 8Y, 8M, 8C, and 8K are attached and detached, and the developing devices 4Y, 4M, 4C, and 4K are each developing devices (colors). And a toner supply pipe (not shown). Further, when the amount of toner stored in the toner cartridge becomes low, the toner cartridge is replaced.

  Hereinafter, although an Example and a comparative example are given and this embodiment is described in detail in detail, this embodiment is not limited to these Examples at all. “Parts” and “%” are based on mass unless otherwise specified.

[Method for producing toner particles]
(Preparation of resin particle dispersion (1))
-Bisphenol A ethylene oxide adduct: 5 mol parts-Bisphenol A propylene oxide adduct: 95 mol parts-Terephthalic acid: 30 mol parts-Fumaric acid: 70 mol parts The above components are stirred, nitrogen introducing tube, temperature sensor, and The flask was put into a 5-liter flask equipped with a rectifying column. Thereafter, the temperature was raised to 210 ° C. over 1 hour, and 1 part of titanium tetraethoxide was added to 100 parts of the material. The temperature was raised to 230 ° C. over 0.5 hours while distilling off the produced water, and after the dehydration condensation reaction was continued at the temperature for 1 hour, the reaction product was cooled to obtain a polyester resin. It was 18,500 when the weight average molecular weight (Mw) of the obtained polyester resin was measured by the gel permeation chromatography (polystyrene conversion).
Next, 40 parts of ethyl acetate and 25 parts of 2-butanol were added to make a mixed solvent, and then 100 parts of a polyester resin was gradually added and dissolved therein. A 10% by mass aqueous ammonia solution (based on the acid value of the resin) 3 times equivalent amount by molar ratio) was added and stirred for 30 minutes.
Next, the inside of the container was replaced with dry nitrogen, the temperature was kept at 40 ° C., and 400 parts of ion-exchanged water was added dropwise at a rate of 2 parts / minute while stirring the mixed solution to carry out emulsification. After completion of the dropwise addition, the emulsion is returned to room temperature (20 ° C. to 25 ° C.), and stirred for 48 hours with dry nitrogen to reduce ethyl acetate and 2-butanol to 1,000 ppm or less. A resin particle dispersion in which resin particles having a diameter of 200 nm were dispersed was obtained. Ion exchange water was added to the resin particle dispersion to obtain a resin particle dispersion (1) having a solid content of 20% by mass.

(Preparation of colorant particle dispersion (1))
Cyan pigment (copper phthalocyanine, CI Pigment blue 15: 3, manufactured by Dainichi Seika): 100 parts Anionic surfactant (Neogen RK, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 10 parts Ion exchange water: 400 parts After mixing the above materials and dispersing for 10 minutes using a homogenizer (Ultra Turrax T50, manufactured by IKA), ion-exchanged water is added, and colorant particles having a volume average particle size of 190 nm and a solid content of 20% by mass A dispersion (1) was obtained.

(Preparation of release agent particle dispersion (1))
-Paraffin wax (HNP9, manufactured by Nippon Seiki Co., Ltd .: melting temperature 75 ° C): 46 parts-Anionic surfactant (Neogen RK, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.): 5 parts-Ion exchange water: 200 parts And heated to 100 ° C. and sufficiently dispersed with a homogenizer (Ultra Turrax T50, manufactured by IKA). Then, it was dispersed with a pressure discharge type gorin homogenizer (manufactured by Gorin) to obtain a release agent particle dispersion (1) having a volume average particle size of 200 nm and a solid content of 20%.

(Production of toner particles (T1))
The round stainless steel flask and the container A are connected by the tube pump A, and the liquid stored in the container A is sent to the flask by driving the tube pump A, and the container A and the container B are connected by the tube pump B. A device (see FIG. 3) for feeding the liquid stored in the container B to the container A by driving the tube pump B was prepared. And the following operation was implemented using this apparatus.

-Resin particle dispersion (1): 500 parts-Colorant particle dispersion (1): 40 parts-Anionic surfactant (TaycaPower): 2 parts The above materials are placed in a round stainless steel flask and 0.1 N After adjusting the pH to 3.5 by adding nitric acid, 30 parts of an aqueous nitric acid solution having a polyaluminum chloride concentration of 10% by mass was added. Subsequently, after dispersing at 30 ° C. using a homogenizer (IKA Ultra Turrax T50), the particle size of the aggregated particles is grown while raising the temperature at a rate of 1 ° C./30 minutes in a heating oil bath. It was.
On the other hand, 150 parts of the resin particle dispersion (1) was put into a container A of a polyester bottle, and 25 parts of the release agent particle dispersion (1) was put into the container B. Next, the liquid feeding speed of the tube pump A is set to 0.70 part / minute, the liquid feeding speed of the tube pump B is set to 0.14 part / minute, and the inside of the round stainless steel flask during the formation of aggregated particles is set. When the temperature reached 37.0 ° C., the tube pumps A and B were driven to start feeding each dispersion liquid. Thereby, while gradually increasing the concentration of the release agent particles, the mixed dispersion in which the resin particles and the release agent particles were dispersed was fed from the container A to the round stainless steel flask in which aggregated particles were being formed. Then, the feeding of each dispersion liquid to the flask was completed, and the liquid was held for 30 minutes from the time when the temperature in the flask reached 48 ° C., thereby forming second aggregated particles.
Thereafter, 50 parts of the resin particle dispersion (1) was gently added and held for 1 hour, and the pH was adjusted to 8.5 by adding a 0.1N aqueous sodium hydroxide solution. Heated to 0 ° C. and held for 5 hours. Thereafter, the mixture was cooled to 20 ° C. at a rate of 20 ° C./min, filtered, sufficiently washed with ion exchange water, and dried to obtain toner particles (T1) having a volume average particle diameter of 6.0 μm. The obtained toner had a volume average particle size of 6.1 μm, an average circularity of 0.95, a distribution of the uneven distribution degree B of the release agent domain, a mode value of 0.88, and a skewness of −0.79. It was.

(Production of toner particles (T2))
In the production of the toner particles (T1), the liquid feeding speed of the tube pump A is set to 0.70 parts / minute, the liquid feeding speed of the tube pump B is set to 0.14 parts / minute, and the temperature in the flask is set to 40. The toner particles (T2) were obtained in the same manner as the toner particles (T1) except that the tube pumps A and B were driven when the temperature reached 0.0 ° C. The obtained toner had a volume average particle size of 6.0 μm, an average circularity of 0.95, a distribution of the uneven distribution degree B of the release agent domain, a mode value of 0.94, and a skewness of −0.80. It was.

(Production of toner particles (T3))
In the production of the toner particles (T1), the liquid feeding speed of the tube pump A is set to 0.70 parts / minute, the liquid feeding speed of the tube pump B is set to 0.14 parts / minute, and the temperature in the flask is 33. The toner particles (T3) were obtained in the same manner as the toner particles (T1) except that the tube pumps A and B were driven when the temperature reached 0.0 ° C. The obtained toner had a volume average particle size of 6.1 μm, an average circularity of 0.95, a distribution of the uneven distribution degree B of the release agent domain, a mode value of 0.77, and a skewness of −0.82. It was.

(Production of toner particles (T4))
In the production of the toner particles (T1), the liquid feeding speed of the tube pump A is set to 0.85 parts / minute, the liquid feeding speed of the tube pump B is set to 0.14 parts / minute, and the temperature in the flask is 37. The toner particles (T4) were obtained in the same manner as the toner particles (T1) except that the tube pumps A and B were driven when the temperature reached 0.0 ° C. The obtained toner had a volume average particle size of 6.2 μm, an average circularity of 0.95, a distribution of the uneven distribution degree B of the release agent domain, a mode value of 0.84, and a skewness of −0.55. It was.

(Production of toner particles (T5))
In the production of the toner particles (T1), the liquid feeding speed of the tube pump A is set to 0.55 parts / minute, the liquid feeding speed of the tube pump B is set to 0.14 parts / minute, and the temperature in the flask is 35. The toner particles (T5) were obtained in the same manner as the toner particles (T1) except that the tube pumps A and B were driven when the temperature reached 0.0 ° C. The obtained toner had a volume average particle diameter of 6.2 μm, an average circularity of 0.95, a distribution of the uneven distribution degree B of the release agent domain, a mode value of 0.88, and a skewness of −1.01. It was.

(Production of toner particles (T6))
In the production of the toner particles (T1), after the second aggregated particles were formed, 50 parts of the resin particle dispersion (1) was gently added and held for 1 hour, and a 0.1N sodium hydroxide aqueous solution was added. After adjusting the pH to 8.5, the toner particles (T6) were obtained in the same manner as the toner particles (T1) except that the mixture was heated to 85 ° C. while stirring was continued and held for 6 hours. The obtained toner had a volume average particle size of 6.3 μm, an average circularity of 0.97, a distribution of the uneven distribution degree B of the release agent domain, a mode value of 0.88, and a skewness of −0.79. It was.

(Production of toner particles (T7))
In the production of the toner particles (T1), after the second aggregated particles were formed, 50 parts of the resin particle dispersion (1) was gently added and held for 1 hour, and a 0.1N sodium hydroxide aqueous solution was added. Then, after adjusting the pH to 8.5, the toner particles (T7) were obtained in the same manner as the toner particles (T1) except that the mixture was heated to 85 ° C. with continuous stirring and held for 4 hours. The obtained toner had a volume average particle size of 6.3 μm, an average circularity of 0.94, a distribution of the uneven distribution degree B of the release agent domain, a mode value of 0.88, and a skewness of −0.79. It was.

(Production of toner particles (T8))
In the production of the toner particles (T1), the liquid feeding speed of the tube pump A is set to 0.90 part / minute, the liquid feeding speed of the tube pump B is set to 0.14 part / minute, and the temperature in the flask is 32. Comparative toner particles (T8) were obtained in the same manner as the toner particles (T1) except that the tube pumps A and B were driven when the temperature reached 0.0 ° C. The obtained toner has a volume average particle diameter of 6.0 μm, an average circularity of 0.94, a distribution of the uneven distribution degree B of the release agent domain is a mode value of 0.92, and a skewness of −0.48. It was.

(Production of toner particles (T9))
In the production of the toner particles (T1), the liquid feeding speed of the tube pump A is set to 0.50 part / minute, the liquid feeding speed of the tube pump B is set to 0.14 part / minute, and the temperature in the flask is 34. Comparative toner particles (T9) were obtained in the same manner as the toner particles (T1) except that the tube pumps A and B were driven when the temperature reached 0.0 ° C. The obtained toner had a volume average particle diameter of 6.1 μm, an average circularity of 0.96, a distribution of the uneven distribution degree B of the release agent domain, a mode value of 0.85, and a skewness of −1.16. It was.

(Production of toner particles (T10))
In the production of the toner particles (T1), the liquid feeding speed of the tube pump A is set to 0.70 parts / minute, the liquid feeding speed of the tube pump B is set to 0.14 parts / minute, and the temperature in the flask is 31. Comparative toner particles (T10) were obtained in the same manner as the toner particles (T1) except that the tube pumps A and B were driven when the temperature reached 0.0 ° C.
The obtained toner had a volume average particle size of 6.1 μm, an average circularity of 0.94, a distribution of the uneven distribution degree B of the release agent domain, a mode value of 0.70, and a skewness of −0.80. It was.

(Production of toner particles (T11))
In the production of the toner particles (T1), after the second aggregated particles were formed, 50 parts of the resin particle dispersion (1) was gently added and held for 1 hour, and a 0.1N sodium hydroxide aqueous solution was added. After adjusting the pH to 8.5, the toner particles (T11) were obtained in the same manner as the toner particles (T1) except that the mixture was heated to 85 ° C. while stirring and maintained for 8 hours. The obtained toner had a volume average particle size of 6.3 μm, an average circularity of 0.99, a distribution of the uneven distribution degree B of the release agent domain was a mode value of 0.88, and a skewness of −0.79. It was.

(Production of toner particles (T12))
In the production of the toner particles (T1), after the second aggregated particles were formed, 50 parts of the resin particle dispersion (1) was gently added and held for 1 hour, and a 0.1N sodium hydroxide aqueous solution was added. After adjusting the pH to 8.5, the toner particles (T12) were obtained in the same manner as the toner particles (T1) except that the mixture was heated to 85 ° C. while continuing stirring and held for 3 hours. The obtained toner had a volume average particle diameter of 6.0 μm, an average circularity of 0.92, a distribution of the uneven distribution degree B of the release agent domain, a mode value of 0.88, and a skewness of −0.79. It was.

(Production of toner particles (T13))
-Preparation of resin particle dispersion (2)-
· Styrene: 320 parts by mass · n-butyl acrylate: 80 parts by mass · β-carboxyethyl acrylate: 9 parts by mass · 1'10-decanediol diacrylate: 1.5 parts by mass · Dodecanethiol: 2.7 parts by mass A solution prepared by dissolving 4 parts of an anionic surfactant (Dowfax, manufactured by Dow Chemical Co., Ltd.) in 550 parts of ion-exchanged water is added to the mixture and dissolved, and the mixture is dispersed and emulsified in a flask, and slowly stirred for 10 minutes. While mixing, 50 parts of ion-exchanged water in which 6 parts of ammonium persulfate was further dissolved was added. Next, after performing nitrogen substitution in the flask, the solution in the flask was heated with an oil bath to 70 ° C. while stirring, and emulsion polymerization was continued as it was for 5 hours to obtain a resin particle dispersion liquid having a solid content of 41% by mass ( 2) was obtained.

Toner particles (T13) were obtained in the same manner as toner particles (T1), except that resin particle dispersion liquid (2) was used instead of resin particle dispersion liquid (1). .
The obtained toner had a volume average particle size of 5.9 μm, an average circularity of 0.96, a distribution of the uneven distribution degree B of the release agent domain, a mode value of 0.89, and a skewness of −0.81. It was.

  The mode of distribution of the degree of uneven distribution B of the release agent domain of each toner particle and the skewness were measured by the method described above. The results are summarized in Table 1.

[Production of silica particles]
(Preparation of silica particles (S1))
-Preparation of silica particle dispersion (S1)-
To a 1.5 L glass reaction vessel equipped with a stirrer, a dropping nozzle, and a thermometer, 300 parts of methanol and 70 parts of 10% ammonia water were added and mixed to obtain an alkali catalyst solution. After adjusting this alkaline catalyst solution to 30 ° C., 169 parts of tetramethoxysilane (TMOS) and 45 parts of 8.0% aqueous ammonia are simultaneously added dropwise with stirring to obtain a hydrophilic silica particle dispersion (solid content concentration of 12 0.0%). Here, the dropping time was 29 minutes. Thereafter, the obtained silica particle dispersion was condensed with a rotary filter R-Fine (manufactured by Kotobuki Industries Co., Ltd.) to a solid content concentration of 40%. This condensed product was used as a silica particle dispersion (S1).

-Production of silica particles (S1)-
To 250 parts of the silica particle dispersion (S1), 62 parts of hexamethyldisilazane (HMDS) is added as a hydrophobizing agent, reacted at 130 ° C. for 2 hours, cooled, and then dried by spray drying. Hydrophobic silica particles (S1) in which the surface of the particles was hydrophobized were obtained.

(Preparation of silica particles (S2) to (S10))
According to Table 2, alkali catalyst solution (amount of methanol and 10% ammonia water), silica particle production conditions (total amount of tetramethoxysilane (TMOS) and 8% ammonia water added to the alkali catalyst, and dropping time), and hydrophobicity Silica particles (S2) to (S10) were produced in the same manner as the silica particles (S1) except that the type and amount of the chemical treatment agent were changed.

  Further, for each of the obtained silica particles, the average circularity and the average primary particle size were measured by the method described above. The results are shown in Table 2.

In Table 2, “TMOS” represents tetramethoxysilane, “HMDS” represents hexamethyldisilazane, and “NH ₃ water” represents ammonia water.

<Example 1>
To 100 parts of toner particles (T1), 0.85 parts of silica particles (S1) and 0.85 parts of silica particles (S2) are added as external additives (first silica particles and second silica particles), and Henschel is added. The toner of Example 1 was obtained by mixing with a mixer at a stirring peripheral speed of 30 m / sec for 15 minutes.

<Examples 2 to 17 and Comparative Examples 1 to 13>
According to Tables 3 and 4, the toner of each example was obtained in the same manner as in Example 1 except that the type of toner particles, the type of external additives (first silica particles, second silica particles) and the number of parts were changed. It was.

<Evaluation>
(Evaluation of thermal cohesion)
1 g of the obtained toner was put in a container and stored in an environment of 45 ° C. and 95% RH for 2 days. The toner state after storage was visually observed and evaluated based on the following evaluation criteria. In addition, let G3 be an allowable range.
G1: Aggregates of toner particles are hardly seen even after storage.
G2: Aggregates of toner particles are observed between G1 and G3 after storage. G3: Aggregates of toner particles are slightly observed after storage.
G4: Toner particles are aggregated after storage.

(Evaluation of color point)
-Production of developer-
Each toner after being stored under the conditions for thermal aggregation evaluation and the carrier prepared under the following conditions are put in a V blender at a ratio of toner: carrier = 8: 92 (mass ratio), and stirred for 20 minutes. Got.

In addition, the carrier produced as follows was used.
Ferrite particles (volume average particle size: 36 μm) 100 parts Toluene 14 parts Styrene-methyl methacrylate copolymer 2 parts (component ratio: 90/10, Mw = 80000)
Carbon black (R330: manufactured by Cabot Corporation) 0.2 part First, the above components except for ferrite particles are stirred for 10 minutes with a stirrer to prepare a dispersed coating solution, and then the coating solution and ferrite particles are combined. After putting in a vacuum degassing type kneader and stirring at 60 ° C. for 30 minutes, the carrier was obtained by further depressurizing while heating and degassing and drying.

The developer of each example was accommodated in a developing device of a modified machine of the image forming apparatus “Apeos PortIVC5575 (manufactured by Fuji Xerox)”. Using this modified image forming apparatus, the image was left for 1 day in a high-temperature and high-humidity environment (28 ° C., 85% RH environment), and 1000 images with an image density of 1% were continuously formed on A4 paper. The occurrence of color spots was visually observed on 100 sheets of 900 to 1000 sheets and evaluated according to the following criteria. The allowable range is up to G3.
-Evaluation criteria-
G1: No color point is generated. G2: One or more color points are generated at least one and two or less G3: Three or more color points are generated at one or more points. G4: Color point The number of occurrences of one or more places exceeds 5

  In Table 1, “R (ave.)” Represents average circularity. Da is the average primary particle size of the first silica particles, Db is the average primary particle size of the second silica particles, and Db-Da is the average primary particle size of the second silica particles and the first The difference from the average primary particle size of the silica particles is expressed respectively.

  From the above results, it can be seen that this example has a better evaluation result of the color point when an image is formed after storing the toner in a high temperature and high humidity environment as compared with the comparative example.

1Y, 1M, 1C, 1K photoconductor (an example of an image carrier)
2Y, 2M, 2C, 2K charging roll (an example of charging means)
3. Exposure device (an example of electrostatic charge image forming means)
3Y, 3M, 3C, 3K Laser beams 4Y, 4M, 4C, 4K Developing device (an example of developing means)
5Y, 5M, 5C, 5K primary transfer roll (an example of primary transfer means)
6Y, 6M, 6C, 6K Photoconductor cleaning device (an example of cleaning means)
8Y, 8M, 8C, 8K Toner cartridge 10Y, 10M, 10C, 10K Image forming unit 20 Intermediate transfer belt (an example of an intermediate transfer member)
22 Drive roll 24 Support roll 26 Secondary transfer roll (an example of secondary transfer means)
30 Intermediate transfer member cleaning device 107 Photosensitive member (an example of an image holding member)
108 Charging roll (an example of charging means)
109 Exposure apparatus (an example of electrostatic charge image forming means)
111 Developing device (an example of developing means)
112 Transfer device (an example of transfer means)
113 photoconductor cleaning device (an example of cleaning means)
115 Fixing device (an example of fixing means)
116 Mounting rail 117 Housing 118 Opening 200 for exposure Process cartridge 300 Recording paper (an example of a recording medium)
P Recording paper (an example of a recording medium)

Claims (10)

It has a sea-island structure including a binder resin and a release agent, and has a sea part containing the binder resin and an island part containing the release agent, and includes the release agent represented by the following formula (1) The mode of the distribution of the uneven distribution degree B of the island is 0.75 or more and 0.98 or less, the skewness of the distribution of the uneven distribution degree B is −1.10 or more and −0.50 or less, and the average circularity Toner particles having a viscosity of 0.94 or more and 0.98 or less;
When the average primary particle diameter of the first silica particles is Da (nm) and the average primary particle diameter of the second silica particles is Db (nm), including the first silica particles and the second silica particles, the following formula ( An external additive satisfying the relationship of A1) to formula (A3);
A toner for developing an electrostatic charge image.
Formula (1): Uneven distribution degree B = 2d / D
(In the formula (1), D represents the equivalent circle diameter (μm) of the toner particles in the cross-sectional observation of the toner particles. The distance (μm) is shown.)
Formula (A1): 80 ≦ Da ≦ 120
Formula (A2): 120 ≦ Db ≦ 200
Formula (A3): 15 ≦ Db−Da ≦ 120   The electrostatic image developing toner according to claim 1, wherein the second silica particles have an average circularity of 0.9 or more and 1.0 or less.   The electrostatic image developing toner according to claim 2, wherein the first silica particles have an average circularity of 0.9 or more and 1.0 or less.   The electrostatic image developing toner according to claim 1, wherein the binder resin is a polyester resin.   The electrostatic image developing toner according to claim 1, wherein the binder resin is a styrene (meth) acrylic resin.   An electrostatic charge image developer comprising the electrostatic charge image developing toner according to claim 1. Containing the toner for developing an electrostatic charge image according to any one of claims 1 to 5,
A toner cartridge to be attached to and detached from the image forming apparatus. A developing means for containing the electrostatic charge image developer according to claim 6 and developing the electrostatic charge image formed on the surface of the image carrier as a toner image by the electrostatic charge image developer,
A process cartridge attached to and detached from the image forming apparatus. An image carrier,
Charging means for charging the surface of the image carrier;
An electrostatic charge image forming means for forming an electrostatic charge image on the surface of the charged image carrier;
Developing means for containing the electrostatic charge image developer according to claim 6 and developing the electrostatic charge image formed on the surface of the image carrier as a toner image by the electrostatic charge image developer;
Transfer means for transferring a toner image formed on the surface of the image carrier to the surface of a recording medium;
Fixing means for fixing the toner image transferred to the surface of the recording medium;
An image forming apparatus comprising: A charging step for charging the surface of the image carrier;
An electrostatic charge image forming step of forming an electrostatic charge image on the surface of the charged image carrier;
A developing step of developing an electrostatic charge image formed on the surface of the image carrier as a toner image with the electrostatic charge image developer according to claim 6;
A transfer step of transferring a toner image formed on the surface of the image carrier to the surface of a recording medium;
A fixing step of fixing the toner image transferred to the surface of the recording medium;
An image forming method comprising: