Image forming system and image forming method

Abstract

To provide an image forming system and an image forming method that achieve both prevention of abrasion of an organic photoreceptor and reduction of attachment on the organic photoreceptor.SOLUTION: An image forming system of the present invention uses an organic photoreceptor, and a toner for electrostatic charge image development including toner particles. The organic photoreceptor has a protective layer containing curable resin. The toner particle has a shape in which at least one type of lubricant particles and at least one type of non-lubricant particles are contained in or attached onto surfaces of a plurality of convex parts or a surface between the plurality of convex parts on a toner base particle having the plurality of convex parts on the surface. An average interval D1 between the convex parts on the surfaces of the toner base particles, a median diameter D2 of the lubricant particle having the smallest median diameter, and a median diameter D3 of the non-lubricant particle having the largest median diameter satisfy the following formula (1). Formula (1) D3≤D1≤D2.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an image forming system and an image forming method. More specifically, the present invention relates to an image forming system that simultaneously suppresses wear of an organic photoreceptor and reduces deposits on the organic photoreceptor. [Background technology]

[0002] In order to extend the life of organic photoreceptors used in electrophotographic image formation, the application of curable resins to the surface layer of the photoreceptor has been investigated (see, for example, Patent Documents 1 and 2). In curable photoreceptors whose surface protective layer contains a curable resin, wear is suppressed and durability is improved. However, suppressing wear makes it difficult for the photoreceptor surface to be refreshed, which creates a new problem: foreign matter originating from toner is more likely to adhere to the photoreceptor surface. The deposits on the photoreceptor can grow and be transferred to a recording medium, or can cause poor charging of the photoreceptor, resulting in a decrease in image quality.

[0003] One method for solving the problem of foreign matter adhering to the photoreceptor is to supply sufficient lubricant particles onto the photoreceptor to reduce adhesion between the foreign matter and the photoreceptor. While a lubricant supply device can be used as a means for supplying lubricant onto the photoreceptor, from the viewpoint of simplifying the device configuration and reducing size, a method of externally adding lubricant to the surface of toner base particles is often adopted. The lubricant particles externally added to the surface of the toner base particles are released from the toner base particles on the photoreceptor and supplied onto the photoreceptor.

[0004] However, in image formation using a curable photoreceptor, the supply of lubricant using conventional lubricant-containing toner alone is not sufficient to reduce adhesion, and a new technology that can simultaneously suppress wear of the organic photoreceptor and reduce adhesion on the organic photoreceptor is required. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-84078 [Patent Document 2] JP 2019-95700 A Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above problems and circumstances, and its problem to be solved is to provide an image forming system and an image forming method that can simultaneously suppress wear of an organic photoreceptor and reduce deposits on the organic photoreceptor. [Means for solving the problem]

[0007] In order to solve the above problems, the inventors have investigated the causes of the above problems and have found that by using an organic photoreceptor having a protective layer containing a cured resin and a toner in which the relationship between the average spacing of convex portions on the surface of the toner base particles, the median diameter of the lubricant particles, and the median diameter of the non-lubricant particles is specified, it is possible to suppress wear of the organic photoreceptor and reduce deposits on the organic photoreceptor at the same time, thereby arriving at the present invention. That is, the above-mentioned problems of the present invention are solved by the following means.

[0008] 1. An image forming system using an organic photoreceptor and a toner for developing an electrostatic image containing toner particles, the organic photoreceptor has a protective layer containing a cured resin, the toner particles have a shape in which at least one type of lubricant particle and at least one type of non-lubricant particle are contained or adhered to the surfaces of the plurality of convex portions or to the surfaces between the plurality of convex portions of the toner base particle, The average interval D1 of the convex portions on the surface of the toner base particle, the median diameter D2 of the lubricant particles having the smallest median diameter, and the median diameter D3 of the non-lubricant particles having the largest median diameter satisfy the relationship of the following formula (1): death, the convex portions contain a hybrid amorphous polyester resin in which a vinyl-based polymerization segment and an amorphous polyester-based polymerization segment are bonded via a bireactive monomer, the lubricant particles are fatty acid metal salt particles, The non-lubricant particles are inorganic particles or organic particles. An image forming system comprising: Formula (1) D3≦D1≦D2

[0011] 2 At least one of the non-lubricant particles has a Mohs hardness of 8 or more. 2. The image forming system according to claim 1,

[0012] 3 The protective layer contains metal oxide particles. 2. The image forming system according to claim 1,

[0013] 4 Equipped with a roller charging system 2. The image forming system according to claim 1,

[0014] 5 In the toner particles, the liberation rate R of the fatty acid metal salt particles from the toner base particles, as determined by an ultrasonic treatment method under the following conditions, is within the range of 20 to 60%: The first feature is 1 Item 1. An image forming system according to item 1. [Conditions for ultrasonic treatment] Step 1: The net intensity W1 of the metal elements originating from the fatty acid metal salt particles in the toner particles is measured by X-ray fluorescence analysis. Step 2: Prepare an aqueous dispersion of toner particles. Step 3: The prepared aqueous dispersion is subjected to ultrasonic treatment. Step 4: The fatty acid metal salt particles liberated from the toner base particles by ultrasonic treatment are removed. Step 5: In the toner particles from which the liberated fatty acid metal salt particles have been removed, the net intensity W2 of the metal elements derived from the fatty acid metal salt particles is measured by fluorescent X-ray analysis. Step 6: Calculate the liberation rate R [%] using the following formula (2). Formula (2) R=(W1-W2) / W1×100

[0015] 6An image forming method using an organic photoreceptor and a toner for developing an electrostatic image containing toner particles, the organic photoreceptor has a protective layer containing a cured resin, the toner particles have a shape in which at least one type of lubricant particle and at least one type of non-lubricant particle are contained or adhered to the surfaces of the plurality of convex portions or to the surfaces between the plurality of convex portions of the toner base particle, The average interval D1 of the convex portions on the surface of the toner base particle, the median diameter D2 of the lubricant particles having the smallest median diameter, and the median diameter D3 of the non-lubricant particles having the largest median diameter satisfy the relationship of the following formula (1): death, the convex portions contain a hybrid amorphous polyester resin in which a vinyl-based polymerization segment and an amorphous polyester-based polymerization segment are bonded via a bireactive monomer, the lubricant particles are fatty acid metal salt particles, The non-lubricant particles are inorganic particles or organic particles. An image forming method comprising: Formula (1) D3≦D1≦D2 [Effects of the Invention]

[0016] The above-described means of the present invention can provide an image forming system and an image forming method that can simultaneously suppress wear of the organic photoreceptor and reduce deposits on the organic photoreceptor.

[0017] The mechanism by which the effects of the present invention are manifested or the mechanism by which it acts has not been clarified, but is speculated as follows.

[0018] The organic photoreceptor used in the image forming system of the present invention is characterized by having a protective layer containing a cured resin. This prevents the photoreceptor from wearing out. However, as described above, the suppression of wear makes it difficult for the photoreceptor surface to be refreshed, which makes it easier for foreign matter to adhere to the photoreceptor surface.

[0019] In image formation using an organic photoreceptor having a protective layer containing a cured resin, the reason why the amount of adhesion cannot be sufficiently reduced by simply supplying a lubricant to the photoreceptor is thought to be that non-lubricant particles that have separated from the toner base particles and adhered to the photoreceptor can act as nuclei for the adhesion of foreign matter. These non-lubricant particles are added externally to the toner base particles to improve the chargeability, heat resistance, fluidity, etc. of the toner. Unlike lubricant particles, non-lubricant particles do not have the function of reducing adhesion of foreign matter to the photoreceptor, and instead can act as nuclei for the adhesion of foreign matter.

[0020] In order to reduce adhesion of matter to the photoreceptor while maintaining the amount of non-lubricant particles added for purposes such as chargeability, it is preferable that the non-lubricant particles are not easily separated from the toner base particles. Non-lubricant particles that are not separated from the toner base particles are likely to be transferred to a recording medium together with the toner base particles or removed in a cleaning process, and are therefore unlikely to become nuclei for foreign matter adhesion.

[0021] On the other hand, as described above, the lubricant particles have the function of reducing adhesion between foreign matter and the photoreceptor by being separated from the toner base particles and supplied onto the photoreceptor, and therefore it is preferable that the lubricant particles are easily separated from the toner base particles.

[0022] Taking these circumstances into consideration, the present invention has realized a toner in which "lubricant particles are easily released from the toner base particles, and non-lubricant particles are not easily released from the toner base particles." Furthermore, by using such a toner together with an organic photoreceptor having a protective layer containing a cured resin, it has become possible to simultaneously suppress wear of the organic photoreceptor and reduce deposits on the organic photoreceptor.

[0023] "A toner in which lubricant particles are easily separated from the toner base particles and non-lubricant particles are difficult to separate from the toner base particles" was achieved by using toner base particles with multiple protrusions on their surfaces and by designing the toner composition so that the relationship in formula (1) below is satisfied.

[0024] Formula (1) D3≦D1≦D2 D1: Average spacing of convex portions on the surface of the toner base particle D2: Median diameter of the lubricant particle with the smallest median diameter D3: Median diameter of the non-lubricant particle with the largest median diameter

[0025] When there are convex portions on the surface of a toner base particle, external additive particles that are smaller than the spacing between the convex portions (≒concave portions) enter the concave portions during external addition and are strongly fixed to the surface of the toner base particle, making them less likely to become detached. On the other hand, external additive particles that are larger than the spacing between the convex portions cannot enter the concave portions during external addition and instead adhere to the surface of the convex portions, reducing the contact area with the toner base particle and making them more likely to become detached.

[0026] The part of formula (1) where D1≦D2 indicates that the median diameter D2 of the lubricant particle with the smallest median diameter is equal to or greater than the average spacing D1 between the convex portions on the surface of the toner base particle. If there is only one type of lubricant particle, the "lubricant particle with the smallest median diameter" refers to the lubricant particle of that type. If there are multiple types of lubricant particles, the "lubricant particle with the smallest median diameter" refers to the lubricant particle of the type with the smallest median diameter among them. When D1≦D2 is satisfied, most of the lubricant particles are made up of particles larger than the spacing between the convex portions of the toner base particle, and therefore the toner is "one in which the lubricant particles are easily released from the toner base particle."

[0027] The part of formula (1) that says D3≦D1 indicates that the median diameter D3 of the non-lubricant particle with the largest median diameter is equal to or less than the average spacing D1 of the convex portions on the surface of the toner base particle. If there is only one type of non-lubricant particle, the "non-lubricant particle with the largest median diameter" refers to the non-lubricant particle of that type. If there are multiple types of non-lubricant particles, the "non-lubricant particle of the type with the largest median diameter" refers to the non-lubricant particle of the type with the largest median diameter. When D3≦D1 is satisfied, most of the non-lubricant particles are composed of particles that are smaller than the spacing between the convex portions of the toner base particle, and therefore the "toner is one in which non-lubricant particles are difficult to separate from the toner base particle."

[0028] Therefore, by designing the toner composition so as to satisfy the relationship of formula (1), it is possible to achieve a toner in which "lubricant particles are easily separated from the toner base particles, and non-lubricant particles are difficult to separate from the toner base particles."

[0029] It is presumed that this mechanism allows the image forming system of the present invention to simultaneously suppress wear of the organic photoreceptor and reduce deposits on the organic photoreceptor. [Brief explanation of the drawings]

[0030] [Figure 1] SEM image of toner base particles with multiple protrusions on the surface [Figure 2] FIG. 1 is an explanatory diagram illustrating the average interval between protrusions on the surface of a toner base particle precursor; [Figure 3] FIG. 1 is a cross-sectional view illustrating an example of the configuration of an image forming apparatus. [Figure 4] FIG. 1 is a cross-sectional view illustrating an example of the configuration of a main part of an image forming apparatus. [Figure 5] Schematic diagram showing an example of the configuration of a charging unit DETAILED DESCRIPTION OF THE INVENTION

[0031] The image forming system of the present invention is an image forming system using an organic photoreceptor and a toner for developing electrostatic images containing toner particles, wherein the organic photoreceptor has a protective layer containing a cured resin, and the toner particles have a shape in which at least one type of lubricant particle and at least one type of non-lubricant particle are contained or adhered to the surface of a plurality of convex portions of a toner base particle having a surface, or to the surface between a plurality of convex portions, and the average spacing D1 of the convex portions on the surface of the toner base particle, the median diameter D2 of the lubricant particle having the smallest median diameter, and the median diameter D3 of the non-lubricant particle having the largest median diameter satisfy the relationship of the following formula (1): Formula (1) D3≦D1≦D2

[0032] This feature is a technical feature common to or corresponding to the following embodiments.

[0033] In an embodiment of the image forming system of the present invention, the convex portions preferably contain a hybrid amorphous polyester resin in which a vinyl-based polymer segment and an amorphous polyester-based polymer segment are bonded via a bireactive monomer. The coexistence of a polyester-based polymer segment and a vinyl-based polymer segment, which has a lower charging property than the polyester-based polymer segment, in the convex portions suppresses excessive charging of the toner particles and reduces the electrostatic adhesion between the toner particles and the organic photoreceptor, thereby further reducing the adhesion of toner-derived foreign matter to the organic photoreceptor. Furthermore, the presence of the vinyl-based polymer segment in the convex portions reduces the electrostatic adhesion between the toner base particles and the lubricant particles, making it easier for the lubricant particles to be supplied onto the organic photoreceptor.

[0034] In an embodiment of the image forming system of the present invention, the lubricant particles are preferably fatty acid metal salt particles. By using positively charged fatty acid metal salt particles as the lubricant particles, excessive charging of the toner is suppressed, and the electrostatic adhesion force between the toner particles and the photoreceptor is reduced, thereby further reducing the adhesion of toner-derived foreign matter to the photoreceptor.

[0035] In an embodiment of the image forming system of the present invention, it is preferable that at least one of the non-lubricant particles has a Mohs hardness of at least 8. The adhesion strength of the non-lubricant particles, which serve as the nucleus material of deposits on the photoreceptor, to the toner base particles is increased, and the amount of liberation is reduced, thereby further reducing deposits on the photoreceptor.

[0036] In an embodiment of the image forming system of the present invention, the protective layer preferably contains metal oxide particles, which suppresses wear and further improves durability.

[0037] In an embodiment of the image forming system of the present invention, it is preferable to have a charging device that is a roller charging type. By using a charging device of the roller charging type, the amount of ozone generated can be significantly reduced, and the applied voltage can be reduced compared to a corona charging type, which has the effect of suppressing power consumption and also enables space saving.

[0038] In an embodiment of the image forming system of the present invention, the toner particles preferably have a liberation rate R of the fatty acid metal salt particles from the toner base particles, determined by the ultrasonic treatment method under the above conditions, within a range of 20 to 60%. If the liberation rate R is 20% or more, an appropriate amount of lubricant particles that can reduce toner adhesion can be supplied to the photoreceptor. Furthermore, if the liberation rate is 60% or less, extreme liberation of the lubricant particles is suppressed, and excessive lubricant particles are not supplied to the photoreceptor, thereby suppressing image defects such as lubricant memory.

[0039] The image forming method of the present invention is an image forming method using an organic photoreceptor and a toner for developing electrostatic images containing toner particles, wherein the organic photoreceptor has a protective layer containing a cured resin, and the toner particles have a shape in which at least one type of lubricant particle and at least one type of non-lubricant particle are contained or adhered to the surface of a plurality of convex portions of a toner base particle having a surface, or to a surface between a plurality of convex portions, and the average spacing D1 of the convex portions on the surface of the toner base particle, the median diameter D2 of the lubricant particle having the smallest median diameter, and the median diameter D3 of the non-lubricant particle having the largest median diameter satisfy the relationship of the following formula (1): Formula (1) D3≦D1≦D2

[0040] The present invention, its components, and embodiments for carrying out the present invention will be described in detail below. In this application, the symbol "to" is used to mean that the numerical values ​​before and after it are included as lower and upper limits.

[0041] <1. Image Forming System Overview> The image forming system of the present invention is an image forming system that uses an organic photoreceptor and a toner for developing electrostatic images (hereinafter simply referred to as "toner") containing toner particles, wherein the organic photoreceptor has a protective layer containing a cured resin, and the toner particles have a shape in which at least one type of lubricant particle and at least one type of non-lubricant particle are contained or adhered to the surface of a plurality of convex portions of a toner base particle having a surface, or to the surface between a plurality of convex portions, and is characterized in that the average spacing D1 of the convex portions on the surface of the toner base particle, the median diameter D2 of the lubricant particle with the smallest median diameter, and the median diameter D3 of the non-lubricant particle with the largest median diameter satisfy the relationship of the following formula (1): Formula (1) D3≦D1≦D2

[0042] In the image forming system of the present invention, the device section is particularly referred to as an "image forming device", and the image forming system of the present invention forms an image by using the image forming device and the toner of the present invention.

[0043] The toner and the image forming apparatus will be described below.

[0044] <2 Toner> In the present invention, "toner" refers to an aggregate of toner particles. Also, "toner particles" refers to toner base particles to which external additives have been added. In the present invention, when there is no need to distinguish between toner base particles and toner particles, they may be simply referred to as toner particles.

[0045] The toner particles according to the present invention are characterized in that they have a shape in which at least one type of lubricant particle and at least one type of non-lubricant particle are contained or adhered to the surfaces of the plurality of convex portions or to the surfaces between the plurality of convex portions of a toner base particle having a plurality of convex portions on the surface thereof.

[0046] Fig. 1 is a scanning electron microscope (SEM) image of a toner base particle according to the present invention. The SEM image in Fig. 1 shows that the toner base particle is composed of a toner base particle precursor 1 and a plurality of protrusions 2 on its surface.

[0047] The toner particles according to the present invention have a shape in which external additives (not shown), such as lubricant particles or non-lubricant particles, are contained or adhered to the surfaces of a plurality of convex portions or the surfaces between a plurality of convex portions of a toner base particle, as shown in the SEM image of FIG.

[0048] In the present invention, the convex portions formed on the surface of the toner base particle are specified as follows. That is, for toner particles contained in an image photographed at 10,000x magnification using an SEM, a profile along the curved surface of the toner base particle is extracted and fitted to the curve. The cross-sectional profile is corrected so that the curve becomes a straight line, and the obtained straight line is extended in a direction perpendicular to the photographed image plane to form a reference plane. A convex portion is defined as a portion that is 30 nm or more away from the obtained reference plane in a direction away from the center of the toner base particle, and the long side length is the longest distance between two parallel lines that sandwich the outline of the portion. The long side length is 30 to 2,000 nm.

[0049] Below, we will explain the relationship between the average spacing of the convex portions on the surface of the toner base particle, the median diameter of the lubricant particles, and the median diameter of the non-lubricant particles (D3≦D1≦D2), which are defined as essential requirements for solving the problems of the present invention, as well as preferred embodiments of the toner.

[0050] <2.1 D3≦D1≦D2> The toner particles according to the present invention are characterized by satisfying the relationship of the following formula (1). As a result, the toner, which is an aggregate of the toner particles, becomes a toner in which the lubricant particles are easily separated from the toner base particles and the non-lubricant particles are difficult to separate from the toner base particles.

[0051] Formula (1) D3≦D1≦D2 D1: Average spacing of convex portions on the surface of the toner base particle D2: Median diameter of the lubricant particle with the smallest median diameter D3: Median diameter of the non-lubricant particle with the largest median diameter

[0052] (Average spacing D1 of convex portions on the surface of the toner base particle) The average spacing D1 between the convex portions is a value determined using SEM image data. How to determine the average spacing D1 between the convex portions will be explained with reference to FIG.

[0053] First, one convex portion having a long side length of 30 nm or more is randomly picked from SEM image data of a toner base particle observed at 10,000x magnification. The picked convex portion is illustrated as convex portion 2a in FIG. 2. Next, with convex portion 2a as the center, four convex portions are picked in order of proximity to convex portion 2a. The four picked convex portions are illustrated as convex portion 2b in FIG. 2. The long side length X of the four picked convex portions 2b is not important. The shortest distances (Y1 to Y4) from the outer periphery of the central convex portion 2a to the outer peripheries of the four picked convex portions 2b are measured, respectively. Next, the average shortest distance Yave is calculated as the average value of Y1 to Y4.

[0054] For the same toner base particle, the first randomly picked convex portion is changed, and the average shortest distance Yave between the centers of 20 convex portions is measured. Furthermore, for a total of five toner base particles, the toner base particle is changed, and the average shortest distance Yave between the centers of 20 convex portions is measured in the same manner. The 100 average shortest distances Yave are averaged to obtain the average spacing D1 between the convex portions.

[0055] D1 is preferably in the range of 20 to 200 nm. If D1 is 20 nm or more, non-lubricant particles can easily enter between convex portions. If D1 is 200 nm or less, the non-lubricant particles are densely present, which increases the adhesion force to the toner base particles and further reduces the amount of liberation.

[0056] (Median diameter D2 of the lubricant particle with the smallest median diameter) The "lubricant particles with the smallest median diameter" in D2 refers to lubricant particles of the same type if there is only one type of lubricant particle, or to the type of lubricant particles with the smallest median diameter if there are multiple types of lubricant particles.

[0057] D2 is preferably in the range of 500 to 3000 nm. If D2 is 500 nm or more, the lubricant particles are less likely to adhere between the convex portions. If D2 is 3000 nm or less, excessive liberation is suppressed, and the lubricant particles are not excessively supplied onto the photoreceptor, thereby suppressing image defects such as lubricant memory.

[0058] (Median diameter D3 of non-lubricant particles with the largest median diameter) The "non-lubricant particles with the largest median diameter" in D3 refers to the non-lubricant particles of the same type if there is only one type of non-lubricant particle, or to the non-lubricant particles of the type with the largest median diameter if there are multiple types of non-lubricant particles.

[0059] D3 is preferably in the range of 50 to 200 nm. If D3 is 50 nm or more, aggregation of non-lubricant particles is suppressed and they easily adhere to the base particle surface as primary particles, making it easier for them to penetrate between convex portions. Furthermore, if D3 is 200 nm or less, adhesion to the toner base particle surface is strengthened, further reducing the amount of liberation.

[0060] (Method for measuring the median diameter of lubricant particles and non-lubricant particles) The median diameters of the lubricant particles and non-lubricant particles in the present invention are measured in accordance with JIS Z 8825-1 (2001). Specifically, the measurement is as follows.

[0061] The measurement device used is the laser diffraction / scattering particle size distribution analyzer "LA-920" (manufactured by HORIBA, Ltd.). The measurement conditions are set and the measurement data is analyzed using the dedicated software "HORIBA LA-920 WET (LA-920) Ver. 2.02" that comes with the LA-920. The measurement solvent used is ion-exchanged water from which impurities such as solids have been removed in advance. The measurement procedure is as follows:

[0062] (1) Attach the batch cell holder to the LA-920. (2) A predetermined amount of ion-exchanged water is placed in the batch cell, and the batch cell is set in the batch cell holder. (3) A special stirrer tip is used to stir the contents of the batch cell. (4) Click the "Refractive Index" button on the "Display Condition Settings" screen and select the file "110A000I" (relative refractive index 1.10). (5) On the "Display Condition Settings" screen, set the particle size standard to volume standard. (6) After warming up for at least one hour, adjust the optical axis, fine-tune the optical axis, and perform a blank measurement. (7) Approximately 60 mL of ion-exchanged water is placed in a 100 mL flat-bottom glass beaker. Approximately 0.3 mL of a solution prepared by diluting Contaminon N (a 10% by weight aqueous solution of a pH 7 neutral detergent for cleaning precision measuring instruments, consisting of a nonionic surfactant, an anionic surfactant, and an organic builder, manufactured by Wako Pure Chemical Industries, Ltd.) with ion-exchanged water approximately three times by weight is added as a dispersant. (8) Prepare an ultrasonic disperser "Ultrasonic Dispension System Tetora150" (manufactured by Nikkaki Bios Co., Ltd.) with an electrical output of 120 W and two built-in oscillators with an oscillation frequency of 50 kHz and a phase difference of 180 degrees. Place approximately 3.3 L of ion-exchanged water in the ultrasonic disperser's water tank and add approximately 2 mL of Contaminon N to this water tank. (9) Set the beaker (7) in the beaker fixing hole of the ultrasonic disperser, operate the ultrasonic disperser, and adjust the height of the beaker so that the resonance state of the aqueous solution in the beaker is maximized. (10) While the aqueous solution in the beaker in (9) is being irradiated with ultrasonic waves, approximately 1 mg of the specimen (particles to be measured) is added little by little to the aqueous solution in the beaker and dispersed. The ultrasonic dispersion process is then continued for another 60 seconds. Note that the specimen may form clumps and float to the surface of the liquid during this process. In this case, the clumps are submerged by shaking the beaker, and ultrasonic dispersion is then continued for 60 seconds. During ultrasonic dispersion, the water temperature in the water bath is appropriately adjusted to 10 to 40°C. (11) The aqueous solution containing the dispersed sample prepared in (10) is immediately added in small amounts to a batch cell, taking care to avoid the introduction of air bubbles, and the transmittance of the tungsten lamp is adjusted to 90-95%. Then, the particle size distribution is measured. The volume-based median diameter is calculated based on the obtained volume-based particle size distribution data.

[0063] 2.2 Toner base particles The toner base particles according to the present invention are characterized by having a plurality of protrusions on the surface.

[0064] As described above, the average spacing D1 between the protrusions is equal to or greater than the median diameter D3 of the non-lubricant particles having the largest median diameter and equal to or less than the median diameter D2 of the lubricant particles having the smallest median diameter. As described above, the average spacing D1 between the protrusions is preferably within the range of 20 to 200 nm.

[0065] The toner base particles having a plurality of convex portions on their surfaces are composed of a toner base particle precursor and a plurality of convex portions formed on the surface of the toner base particle precursor. The toner base particle precursor may be composed of a resin for the toner base particle precursor, a colorant, a release agent, a charge control agent, etc. The convex portions may be composed of a resin for the convex portions.

[0066] (1) Resin for toner base particle precursor The resin for the toner base particle precursor preferably contains, for example, a vinyl resin, and more preferably contains a vinyl resin and a crystalline resin.

[0067] In the present invention, a "crystalline resin" refers to a resin that has a melting point, i.e., a clear endothermic peak, when heated, in an endothermic curve obtained by differential scanning calorimetry (DSC). A "clear endothermic peak" refers to a peak with a half-width of 15°C or less in an endothermic curve obtained when the temperature is increased at a heating rate of 10°C / min. On the other hand, an "amorphous resin" refers to a resin that, in an endothermic curve obtained by performing the same differential scanning calorimetry as above, shows a baseline curve indicating the occurrence of a glass transition, but does not show the clear endothermic peak described above.

[0068] (1-1) Vinyl resin The vinyl resin according to the present invention is a resin obtained by polymerization of at least a vinyl monomer. Specific examples of amorphous vinyl resins include acrylic resins and styrene-acrylic copolymer resins. Among these, styrene-acrylic resins, which are obtained by polymerizing a styrene monomer and an acrylic monomer, are preferred as amorphous vinyl resins. This provides the effect of more reliably suppressing the occurrence of filming.

[0069] Examples of polymerizable monomers used in the styrene-acrylic resin include aromatic vinyl monomers and (meth)acrylic acid ester monomers, and those having an ethylenically unsaturated bond capable of undergoing radical polymerization are preferred.

[0070] Examples of aromatic vinyl monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, p-ethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, 2,4-dimethylstyrene, 3,4-dichlorostyrene, and derivatives thereof. These aromatic vinyl monomers can be used alone or in combination of two or more.

[0071] Examples of (meth)acrylic acid ester monomers include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, etc. These (meth)acrylic acid ester monomers can be used alone or in combination of two or more.

[0072] Among the above, it is preferable to use a styrene-based monomer in combination with an acrylic acid ester-based monomer or a methacrylic acid ester-based monomer.

[0073] The polymerizable monomer may also be a third vinyl monomer, such as an acid monomer such as acrylic acid, methacrylic acid, maleic anhydride, or vinylacetic acid, acrylamide, methacrylamide, acrylonitrile, ethylene, propylene, butylene vinyl chloride, N-vinylpyrrolidone, or butadiene.

[0074] The polymerizable monomer may further include a polyfunctional vinyl monomer. Examples of polyfunctional vinyl monomers include diacrylates of ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, and the like; and dimethacrylates and trimethacrylates of tertiary or higher alcohols such as divinylbenzene, pentaerythritol, and trimethylolpropane. The copolymerization ratio of the polyfunctional vinyl monomer to the total polymerizable monomers is typically within the range of 0.001 to 5% by mass, preferably 0.003 to 2% by mass, and more preferably 0.01 to 1% by mass. The use of the polyfunctional vinyl monomer generates a gel component insoluble in tetrahydrofuran, but the proportion of the gel component in the total polymer is typically 40% by mass or less, preferably 20% by mass or less.

[0075] (1-2) Crystalline resin The crystalline resin contained in the toner base particle precursor according to the present invention is preferably contained in an amount of 3 to 20% by mass, and more preferably 5 to 15% by mass, based on the total mass of the resin contained in the toner base particles. When the amount is 3% by mass or more, good fixability is achieved, and when the amount is 20% by mass or less, a decrease in heat resistance due to excessive presence of the crystalline resin on the surfaces of the toner base particle precursor and the toner base particles can be prevented, and transfer defects due to a decrease in electrical resistance can also be prevented.

[0076] The crystalline resin contained in the toner base particle precursor according to the present invention may be any known crystalline resin.

[0077] From the viewpoint of obtaining excellent low-temperature fixability, it is preferable that the toner base particles contain a crystalline polyester resin as the crystalline resin, and the content of the crystalline polyester resin in the toner base particles is, for example, in the range of 3 to 20% by mass. When the content is 3% by mass or more, sufficient low-temperature fixability can be obtained more reliably, and when it is 20% by mass or less, toner scattering due to a decrease in chargeability can be more reliably suppressed.

[0078] The crystalline polyester resin is a resin that exhibits crystallinity among polyester resins obtained by a polymerization reaction between a divalent or higher carboxylic acid (polycarboxylic acid) monomer and a divalent or higher alcohol (polyalcohol) monomer.

[0079] Examples of polycarboxylic acid monomers that can be used in the synthesis of crystalline polyester resins include saturated aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, n-dodecylsuccinic acid, 1,10-decanedicarboxylic acid (dodecanedioic acid), and 1,12-dodecanedicarboxylic acid (tetradecanedioic acid); alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, and terephthalic acid; trivalent or higher polycarboxylic acids such as trimellitic acid and pyromellitic acid; and anhydrides and alkyl esters having 1 to 3 carbon atoms of these carboxylic acid compounds. These may be used alone or in combination of two or more.

[0080] Examples of polyhydric alcohol monomers that can be used in the synthesis of crystalline polyester resins include aliphatic diols such as 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, neopentyl glycol, and 1,4-butenediol; and trihydric or higher polyhydric alcohols such as glycerin, pentaerythritol, trimethylolpropane, and sorbitol. These may be used alone or in combination of two or more.

[0081] (1-3) Glass transition temperature and softening point of the resin for the toner base particle precursor The glass transition temperature Tg of the toner base particle precursor resin is preferably within a range of, for example, 40 to 60° C. The softening point Tsp of the toner base particle precursor resin is preferably within a range of, for example, 80 to 130° C.

[0082] In the present invention, the glass transition temperature Tg of the resin for the toner base particle precursor can be measured by the method (DSC method) specified in ASTM (American Society for Testing and Materials) D3418-82.

[0083] Specifically, 3.0 mg of sample was weighed accurately to two decimal places, sealed in an aluminum pan, and set in the sample holder of a differential scanning calorimeter "Diamond DSC" (manufactured by PerkinElmer). An empty aluminum pan was used as a reference. Temperature control was performed using a heating-cooling-heating cycle with a measurement temperature range of 0 to 200°C, a heating rate of 10°C / min, and a cooling rate of 10°C / min. Analysis was performed based on the data from the second heating cycle. The glass transition temperature (Tg) was determined as the intersection point between the extension of the baseline before the onset of the first endothermic peak and the tangent line representing the maximum slope from the onset of the first endothermic peak to the peak apex.

[0084] In the present invention, the softening point Tsp of the resin for the toner base particle precursor can be measured as follows.

[0085] First, in an environment of 20±1°C and 50±5% RH, 1.1 g of resin was placed in a petri dish and flattened. After leaving it for 12 hours or more, it was pressed at 3820 kg / cm using a molding machine "SSP-10A" (Shimadzu Corporation). 2 The molded sample was then extruded from the cylindrical die hole (1 mm diameter x 1 mm) using a piston with a diameter of 1 cm at the end of preheating under the conditions of a load of 196 N (20 kgf), a starting temperature of 60 °C, a preheating time of 300 seconds, and a heating rate of 6 °C / min using a flow tester "CFT-500D" (Shimadzu Corporation). The offset temperature T was measured using the melt temperature measurement method with an offset value of 5 mm. offset is the softening point Tsp of the resin.

[0086] (1-4) Method for producing resin for toner base particle precursor The toner base particle precursor resin according to the present invention is preferably prepared by, for example, emulsion polymerization. Emulsion polymerization can be carried out by dispersing polymerizable monomers such as styrene and acrylic acid esters in an aqueous medium and polymerizing them. A dispersion stabilizer is preferably used to disperse the polymerizable monomers in the aqueous medium, and a polymerization initiator, a chain transfer agent, etc. can be used for polymerization.

[0087] (1-4-1) Dispersion stabilizer When preparing a resin for toner base particle precursors by emulsion polymerization by dispersing a polymerizable monomer in an aqueous medium, a dispersion stabilizer is usually added to prevent aggregation of the dispersed droplets. Known surfactants can be used as the dispersion stabilizer, and dispersion stabilizers selected from cationic surfactants, anionic surfactants, nonionic surfactants, etc. can be used. These surfactants can be used alone or in combination of two or more. The dispersion stabilizer can also be used in dispersions of colorants, offset inhibitors, etc.

[0088] Specific examples of cationic surfactants include dodecylammonium bromide, dodecyltrimethylammonium bromide, dodecylpyridinium chloride, dodecylpyridinium bromide, and hexadecyltrimethylammonium bromide.

[0089] Specific examples of nonionic surfactants include dodecyl polyoxyethylene ether, hexadecyl polyoxyethylene ether, norylphenyl polyoxyethylene ether, lauryl polyoxyethylene ether, sorbitan monooleate polyoxyethylene ether, styrylphenyl polyoxyethylene ether, and monodecanoyl sucrose.

[0090] Specific examples of anionic surfactants include aliphatic soaps such as sodium stearate and sodium laurate, sodium lauryl sulfate, sodium dodecylbenzenesulfonate, and polyoxyethylene (2) lauryl ether sodium sulfate.

[0091] (1-4-2) Polymerization initiator The polymerization initiator used for the polymerization of the resin for the toner base particle precursor is not particularly limited, and known initiators can be used. Specifically, for example, hydrogen peroxide, acetyl peroxide, cumyl peroxide, tert-butyl peroxide, propionyl peroxide, benzoyl peroxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, lauroyl peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, diisopropyl peroxycarbonate, tetralin hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide, triphenylacetic acid tert-hydroperoxide, tert-butyl performate, and tert-butyl peracetic acid. Examples of the polymerization initiator include peroxides such as tert-butyl perbenzoate, tert-butyl perphenylacetate, tert-butyl permethoxyacetate, and tert-butyl per-N-(3-toluyl)palmitate; and azo compounds such as 2,2'-azobis(2-aminodipropane) hydrochloride, 2,2'-azobis(2-aminodipropane) nitrate, 1,1'-azobis(1-methylbutyronitrile-3-sodium sulfonate), 4,4'-azobis-4-cyanovaleric acid, and poly(tetraethylene glycol-2,2'-azobisisobutyrate). The amount of polymerization initiator added varies depending on the desired molecular weight and molecular weight distribution, but is preferably within the range of 0.1 to 5.0% by mass, for example, relative to the polymerizable monomer.

[0092] (1-4-3) Chain transfer agent In the production of the toner base particle precursor resin according to the present invention, a chain transfer agent may be added together with the polymerizable monomer. The molecular weight of the polymer can be controlled by adding a chain transfer agent. When polymerizing the aromatic vinyl monomer and (meth)acrylic acid ester monomer, a commonly used chain transfer agent can be used to adjust the molecular weight of the styrene-acrylic polymer segment. The chain transfer agent is not particularly limited, and examples thereof include alkyl mercaptans and mercapto fatty acid esters.

[0093] The amount of the chain transfer agent added varies depending on the desired molecular weight and molecular weight distribution, but specifically, it is preferably within the range of, for example, 0.1 to 5.0% by mass based on the polymerizable monomer.

[0094] (2) Release agent The toner base particle precursor may contain a release agent such as wax.

[0095] Examples of waxes include hydrocarbon waxes such as low-molecular-weight polyethylene wax, low-molecular-weight polypropylene wax, Fischer-Tropsch wax, microcrystalline wax, and paraffin wax, and ester waxes such as carnauba wax, pentaerythritol behenate, behenyl behenate, and behenyl citrate. These may be used alone or in combination of two or more.

[0096] The wax to be used preferably has a melting point within the range of 50 to 95° C. in order to ensure that the toner has low-temperature fixability and releasability.

[0097] In the present invention, the melting point of the release agent can be determined by differential scanning calorimetry (DSC) of the toner. For the DSC, a differential scanning calorimeter "Diamond DSC" (manufactured by PerkinElmer) can be used. The measurement is performed under the following measurement conditions (heating and cooling conditions): a first heating process in which the temperature is raised from 0°C to 200°C at a rate of 10°C / min and isothermally maintained at 200°C for 5 minutes; a cooling process in which the temperature is lowered from 200°C to 0°C at a rate of 10°C / min and isothermally maintained at 0°C for 5 minutes; and a second heating process in which the temperature is raised from 0°C to 200°C at a rate of 10°C / min. The above measurement is performed by sealing 3.0 mg of the release agent in an aluminum pan and setting it in the sample holder of the DSC differential scanning calorimeter. An empty aluminum pan is used as a reference. In the above measurement, an analysis is performed on the endothermic curve obtained in the first temperature rise process, and the top temperature of the endothermic peak derived from the release agent component is taken as the melting point [°C].

[0098] The wax content is preferably within a range of 2 to 20% by mass, more preferably within a range of 3 to 18% by mass, and even more preferably within a range of 4 to 15% by mass, based on the total amount of the resin for the toner base particle precursor.

[0099] (3) Coloring agent As the colorant that can be contained in the toner base particle precursor, for example, carbon black, magnetic material, dye, pigment, etc. can be used arbitrarily.

[0100] Examples of carbon black that can be used include channel black, furnace black, acetylene black, thermal black, and lamp black.

[0101] As the magnetic material, for example, ferromagnetic metals such as iron, nickel, and cobalt, alloys containing these metals, and compounds of ferromagnetic metals such as ferrite and magnetite can be used.

[0102] Examples of pigments include CI Pigment Red 2, 3, 5, 7, 15, 16, 48:1, 48:3, 53:1, 57:1, 81:4, 122, 123, 139, 144, 149, 166, 177, 178, 208, 209, 222, CI Pigment Orange 31, 43, CI Pigment Yellow 3, 9, 14, 17, 35, Examples of pigments that can be used include phthalocyanine pigments having a central metal such as zinc, titanium, magnesium, etc., such as CI Pigment Green 7, CI Pigment Blue 15:3, CI Pigment Blue 15:4, CI Pigment Green 60, and mixtures of these pigments.

[0103] Examples of dyes include CI Solvent Red 1, 3, 14, 17, 18, 22, 23, 49, 51, 52, 58, 63, 87, 111, 122, 127, 128, 131, 145, 146, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 176, 179, and pyrazolothria. Examples of suitable dyes include azole azo dyes, pyrazolotriazole azomethine dyes, pyrazolone azo dyes, pyrazolone azomethine dyes, CI Solvent Yellow 19, 44, 77, 79, 81, 82, 93, 98, 103, 104, 112, 162, CI Solvent Blue 25, 36, 60, 70, 93, and 95, and mixtures thereof can also be used.

[0104] The content of the colorant is preferably in the range of 1 to 30% by mass, more preferably in the range of 2 to 20% by mass, based on the total amount of the resin for the toner base particle precursor.

[0105] (4) Charge control agent As the charge control agent that can be contained in the toner base particle precursor, various known ones can be used.

[0106] As the charge control agent, for example, various known compounds that can be dispersed in an aqueous medium can be used, and specific examples include nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, metal salicylate salts or metal complexes thereof, etc.

[0107] The content of the charge control agent is preferably in the range of 0.1 to 10.0% by mass, more preferably in the range of 0.5 to 5.0% by mass, based on the total amount of the resin for the toner base particle precursor.

[0108] (5) Other additives The toner base particle precursor may contain other additives as needed, such as magnetic powder, a flowability improver, a conductivity adjuster, a reinforcing filler such as a fibrous substance, an antioxidant, and a cleaning property improver.

[0109] (6) Average circularity of toner base particle precursor The average circularity of the toner base particle precursor is preferably 0.890 or more.

[0110] The average circularity of the toner base particle precursor is the arithmetic mean value of the circularity obtained by adding up the circularity of each toner base particle precursor and dividing the sum by the total number of particles measured.

[0111] The circularity of the toner base particle precursor can be measured using a flow particle image analyzer "FPIA-2100" (manufactured by Sysmex Corporation). Specifically, the toner base particle precursor is wetted in a surfactant aqueous solution, ultrasonically dispersed for one minute, and then dispersed. After dispersion, the circularity is measured using the "FPIA-2100" in the HPF (high magnification imaging) mode under measurement conditions at an appropriate concentration within the HPF detection count range of 3,000 to 10,000 particles. Within this range, reproducible measured values ​​can be obtained. When toner base particles are produced by the emulsion aggregation method, the process of wetting the particles in the surfactant aqueous solution and ultrasonically dispersing them for one minute can be omitted because they are produced using a wet method.

[0112] The circularity is calculated by the following formula: Circularity = (perimeter of a circle with the same projected area as the particle image) / (perimeter of the projected particle image)

[0113] (7) Resin for convex parts As the resin for the convex portion, for example, when a polyester resin is used for the resin for the toner base particle precursor, it is preferable that the resin contains a vinyl resin or the like, and when a vinyl resin is used for the resin for the toner base particle precursor, it is preferable that the resin for the convex portion contains a hybrid amorphous polyester resin in which a vinyl-based polymer segment and a polyester-based polymer segment are bonded via a bireactive monomer.

[0114] (7-1) Hybrid amorphous polyester resin "Hybrid amorphous polyester resin" is a resin in which a vinyl-based polymer segment composed of a styrene-acrylic polymer, etc., and a polyester-based polymer segment composed of an amorphous polyester resin are bonded via a bireactive monomer.

[0115] The resin for the convex portions preferably contains a hybrid crystalline polyester resin. The coexistence of polyester-based polymer segments and vinyl-based polymer segments, which have lower charging properties than the polyester-based polymer segments, in the convex portions suppresses excessive charging of toner particles and reduces the electrostatic adhesion between the toner particles and the photoreceptor, thereby further reducing the adhesion of toner-derived foreign matter to the photoreceptor. Furthermore, the presence of vinyl-based polymer segments in the convex portions reduces the electrostatic adhesion between the toner base particles and the lubricant particles, making it easier for the lubricant particles to be supplied onto the photoreceptor.

[0116] The vinyl polymer segment refers to a polymer portion obtained by polymerizing a vinyl monomer, and is preferably a polymer portion obtained by polymerizing an aromatic vinyl monomer and a (meth)acrylic acid ester monomer.

[0117] In the present invention, the content of the vinyl-based polymerized segment in the hybrid amorphous polyester resin is preferably, for example, within a range of 5 to 30 mass %, particularly preferably within a range of 10 to 20 mass %, relative to the total mass of the hybrid amorphous polyester resin. The hybrid amorphous polyester resin preferably contains the polyester-based polymerized segment in a range of, for example, 50 to 95 mass %.

[0118] By including a vinyl-based polymer segment in the hybrid amorphous polyester resin in the range of 5 to 30% by mass, it is possible to make it difficult for the protrusions to detach from the toner base particles, thereby improving the durability of the toner base particles. Furthermore, it is possible to make it difficult for the protrusions to coalesce with each other during toner preparation, and it is possible to make it difficult for the crystalline resin to be exposed on the surface of the toner base particle precursor, thereby fully achieving the effect of the protrusions.

[0119] The content of the vinyl-based polymerization segment in the hybrid amorphous polyester resin specifically refers to the ratio of the mass of the vinyl-based monomer that becomes the vinyl-based polymerization segment to the total mass of the resin materials used to synthesize the hybrid amorphous polyester resin, i.e., the total mass of the polymerizable monomer that forms the unmodified polyester resin that becomes the polyester-based polymerization segment, the vinyl-based monomer that becomes the vinyl-based polymerization segment, and the bireactive monomer that bonds these.

[0120] Furthermore, it is preferable that the content of the hybrid amorphous polyester resin in the toner base particles is, for example, within the range of 5 to 20% by mass of the total amount of resin, in order to obtain the effect of the convex portions without impairing the fixability.

[0121] From the viewpoint of low-temperature fixability, the hybrid amorphous polyester resin preferably has a glass transition temperature Tg in the range of 50 to 70°C, more preferably in the range of 50 to 65°C, and a softening point Tsp in the range of 80 to 110°C.

[0122] The glass transition temperature Tg of the hybrid amorphous polyester resin is a value measured by the method (DSC method) specified in ASTM (American Society for Testing and Materials) D3418-12el, and can be measured by the same measurement method as that for the resin for the toner base particle precursor described above.

[0123] The softening point Tsp of the hybrid amorphous polyester resin can be measured by the same method as the softening point Tsp of the resin for the toner base particle precursor described above.

[0124] (7-2) Method for producing hybrid amorphous polyester resin The hybrid amorphous polyester resin can be produced by any of the existing general schemes. Typical methods include the following four (A) to (D). The following examples illustrate the case where the vinyl polymerized segment is a polymer portion obtained by polymerizing an aromatic vinyl monomer and a (meth)acrylic acid ester monomer.

[0125] (A) A method of forming a vinyl polymerization segment by first polymerizing a polyester polymerization segment, reacting the polyester polymerization segment with a bireactive monomer, and then reacting an aromatic vinyl monomer and a (meth)acrylic acid ester monomer to form a vinyl polymerization segment. That is, a method of polymerizing the aromatic vinyl monomer and the (meth)acrylic acid ester monomer to form the vinyl polymerization segment in the presence of a bireactive monomer having a polymerizable unsaturated group and a group reactive with a polycarboxylic acid monomer or a polyhydric alcohol monomer to form the polyester polymerization segment, and an unmodified polyester resin.

[0126] (B) A method of forming a polyester-based polymerization segment by polymerizing a vinyl-based polymerization segment in advance, reacting the vinyl-based polymerization segment with a bireactive monomer, and further reacting the vinyl-based polymerization segment with a polycarboxylic acid monomer and a polyhydric alcohol monomer for forming a polyester-based polymerization segment.

[0127] (C) A method in which a polyester polymerized segment and a vinyl polymerized segment are polymerized in advance, and then the two are bonded together by reacting them with a bireactive monomer.

[0128] (D) A method in which a polyester polymerized segment is polymerized in advance, and then a vinyl polymerizable monomer is addition polymerized to the polymerizable unsaturated group of the polyester polymerized segment, or reacted with a vinyl group in the vinyl polymerized segment to bond the two.

[0129] Here, the bireactive monomer is a monomer having a group capable of reacting with a polycarboxylic acid monomer or a polyhydric alcohol monomer for forming a polyester-based polymer segment of the hybrid amorphous polyester resin, and a polymerizable unsaturated group.

[0130] Specifically, method (A) involves a mixing step in which an unmodified polyester resin is mixed with an aromatic vinyl monomer, a (meth)acrylic acid ester monomer, and a bireactive monomer to form a polyester polymerized segment, followed by a polymerization step in which the aromatic vinyl monomer and the (meth)acrylic acid ester monomer are polymerized in the presence of the bireactive monomer and the unmodified polyester resin to form a vinyl polymerized segment at the end of the polyester polymerized segment. In this case, the hydroxyl group at the end of the polyester polymerized segment forms an ester bond with the carboxyl group of the bireactive monomer, and the vinyl group of the bireactive monomer bonds with the vinyl group of the aromatic vinyl monomer or the (meth)acrylic acid monomer, thereby forming the vinyl polymerized segment. Among the above synthesis methods, method (A) is the most preferred.

[0131] In the mixing step, heating is preferably performed. The heating temperature may be within a range that allows mixing of the unmodified polyester resin, aromatic vinyl monomer, (meth)acrylic acid ester monomer, and bireactive monomer. Specifically, from the viewpoint of allowing these materials to be mixed well and facilitating polymerization control, the heating temperature is preferably within a range of, for example, 80 to 120°C, more preferably within a range of 85 to 115°C, and even more preferably within a range of 90 to 110°C.

[0132] The relative proportions of the aromatic vinyl monomer and the (meth)acrylic acid ester monomer are preferably such that the glass transition temperature Tg calculated by the FOX formula represented by the following formula (i) is in the range of 35 to 80°C, preferably 40 to 60°C. Formula (i): 1 / Tg = Σ(Wx / Tgx) (In the above formula (i), Wx represents the mass fraction of the monomer x, and Tgx represents the glass transition point of the homopolymer of the monomer x.)

[0133] In the present invention, the bireactive monomer is not used in the calculation of the glass transition temperature.

[0134] The polymerization temperature in the polymerization step of polymerizing the aromatic vinyl monomer and the (meth)acrylic acid ester monomer is not particularly limited and can be appropriately selected within a range in which the polymerization between the aromatic vinyl monomer and the (meth)acrylic acid ester monomer and the bonding to the polyester resin proceeds. For example, the temperature is preferably within a range of 85 to 125°C, more preferably within a range of 90 to 120°C, and even more preferably within a range of 95 to 115°C.

[0135] In the production of the hybrid amorphous polyester resin, it is practically preferable that the volatile organic substances from the emulsion of residual monomers and the like after the polymerization step be suppressed to 1000 ppm or less, more preferably 500 ppm or less, and even more preferably 200 ppm or less.

[0136] (7-2-1) Polyester polymer segment The resin used to prepare the polyester-based polymer segment constituting the hybrid amorphous polyester resin according to the present invention is preferably one obtained by a polycondensation reaction using a polycarboxylic acid monomer (derivative) and a polyhydric alcohol monomer (derivative) as raw materials in the presence of an appropriate catalyst.

[0137] As the polycarboxylic acid monomer, for example, alkyl esters, acid anhydrides, and acid chlorides of polycarboxylic acid monomers can be used, and as the polyhydric alcohol monomer, for example, esters of polyhydric alcohol monomers and hydroxycarboxylic acids can be used.

[0138] Examples of polycarboxylic acid monomers include oxalic acid, succinic acid, maleic acid, mesaconic acid, adipic acid, β-methyladipic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, fumaric acid, citraconic acid, diglycolic acid, cyclohexane-3,5-diene-1,2-dicarboxylic acid, malic acid, citric acid, hexahydroterephthalic acid, malonic acid, pimelic acid, tartaric acid, mucic acid, phthalic acid, isophthalic acid, terephthalic acid, tetrachlorophthalic acid, chlorophthalic acid, nitrophthalic acid, p-carboxyphenyl Examples of suitable carboxylic acids include dicarboxylic acids such as m-phenylenediglycolic acid, p-phenylenediglycolic acid, o-phenylenediglycolic acid, diphenylacetic acid, diphenyl-p,p'-dicarboxylic acid, naphthalene-1,4-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-2,6-dicarboxylic acid, anthracenedicarboxylic acid, and dodecenylsuccinic acid; and tricarboxylic acids or higher such as trimellitic acid, pyromellitic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, pyrenetricarboxylic acid, and pyrenetetracarboxylic acid.

[0139] Among them, as the polycarboxylic acid monomer, it is preferable to use unsaturated aliphatic dicarboxylic acids such as fumaric acid, maleic acid, mesaconic acid, etc., and it is particularly preferable to use unsaturated aliphatic dicarboxylic acids represented by the above general formula (A). In addition, in the present invention, anhydrides of dicarboxylic acids such as maleic anhydride can also be used.

[0140] Examples of polyhydric alcohol monomers include dihydric alcohols such as ethylene glycol, propylene glycol, butanediol, diethylene glycol, hexanediol, cyclohexanediol, octanediol, decanediol, dodecanediol, an ethylene oxide adduct of bisphenol A, and a propylene oxide adduct of bisphenol A; and trihydric or higher polyols such as glycerin, pentaerythritol, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, and tetraethylolbenzoguanamine.

[0141] In order to form the polyester polymer segment constituting the hybrid amorphous polyester resin according to the present invention, it is preferable to use a monomer that does not contain a linear alkyl group as the polycarboxylic acid and polyhydric alcohol.

[0142] The ratio of the polycarboxylic acid monomer to the polyhydric alcohol monomer is, for example, an equivalent ratio [OH] / [COOH] of the hydroxy group [OH] of the polyhydric alcohol monomer to the carboxy group [COOH] of the polycarboxylic acid, which is preferably within a range of 1.5 / 1 to 1 / 1.5, and more preferably within a range of 1.2 / 1 to 1 / 1.2.

[0143] As the catalyst used for synthesizing the polyester polymer segment, various known catalysts can be used.

[0144] The amorphous polyester resin constituting the polyester-based polymerization segment preferably has a glass transition temperature Tg in the range of 40 to 70°C, more preferably in the range of 50 to 65°C. When the glass transition temperature Tg of the amorphous polyester resin is 40°C or higher, the cohesive strength of the amorphous polyester resin in the high temperature range becomes appropriate, and the occurrence of the hot offset phenomenon during fixing is suppressed. Furthermore, when the glass transition temperature of the amorphous polyester resin is 70°C or lower, the resin can be sufficiently melted during fixing, and a sufficient minimum fixing temperature can be ensured.

[0145] The weight-average molecular weight Mw of the amorphous polyester resin is, for example, preferably in the range of 1,500 to 60,000, and more preferably in the range of 3,000 to 40,000. When the weight-average molecular weight is 1,500 or more, the toner base particles as a whole have a suitable cohesive force, and the occurrence of high-temperature offset during fixing is suppressed. When the weight-average molecular weight is 60,000 or less, a sufficient melt viscosity can be obtained, and a sufficient minimum fixing temperature can be ensured, and the occurrence of low-temperature offset during fixing is suppressed.

[0146] The amorphous polyester resin may have a partially branched structure or a crosslinked structure formed by, for example, selecting the carboxylic acid valence or alcohol valence of the polyvalent carboxylic acid monomer or polyhydric alcohol monomer used.

[0147] (7-2-2) Bireactive Monomer The bireactive monomer for forming the vinyl-based polymerization segment may be a monomer having a group capable of reacting with the polycarboxylic acid monomer or polyhydric alcohol monomer for forming the polyester-based polymerization segment and a polymerizable unsaturated group. Specific examples of the bireactive monomer that can be used include acrylic acid, methacrylic acid, fumaric acid, maleic acid, and maleic anhydride. In the present invention, it is preferable to use acrylic acid or methacrylic acid as the bireactive monomer.

[0148] The proportion of the bireactive monomer used is preferably within a range of 0.1 to 5.0 mass%, and more preferably within a range of 0.5 to 3.0 mass%, when the total mass of the resin material used, that is, the total mass of the unmodified polyester resin, aromatic vinyl monomer, (meth)acrylic acid ester monomer, and bireactive monomer, is taken as 100 mass%.

[0149] (7-2-3) Vinyl polymer segment The aromatic vinyl monomer and (meth)acrylic acid ester monomer for forming the vinyl polymerized segment have an ethylenically unsaturated bond that can undergo radical polymerization.

[0150] Examples of aromatic vinyl monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-methoxystyrene, p-phenylstyrene, p-chlorostyrene, p-ethylstyrene, pn-butylstyrene, p-tert-butylstyrene, pn-hexylstyrene, pn-octylstyrene, pn-nonylstyrene, pn-decylstyrene, pn-dodecylstyrene, 2,4-dimethylstyrene, 3,4-dichlorostyrene, and derivatives thereof. These aromatic vinyl monomers can be used alone or in combination of two or more.

[0151] Examples of (meth)acrylic acid ester monomers include methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, propyl γ-aminoacrylate, stearyl methacrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, etc. These (meth)acrylic acid ester monomers can be used alone or in combination of two or more.

[0152] As the aromatic vinyl monomer and (meth)acrylic acid ester monomer for forming the vinyl polymer segment, it is preferable to use a large amount of styrene or its derivatives from the viewpoint of obtaining excellent electrostatic chargeability, image quality characteristics, etc. Specifically, it is preferable that the amount of styrene or its derivatives used is, for example, 50% by mass or more of the total monomers (aromatic vinyl monomer and (meth)acrylic acid ester monomer) used to form the styrene-acrylic polymer segment.

[0153] (7-2-4) Polymerization initiator In the polymerization step of polymerizing the aromatic vinyl monomer and the (meth)acrylic acid ester monomer, the polymerization is preferably carried out in the presence of a radical polymerization initiator. The timing of adding the radical polymerization initiator is not particularly limited, but it is preferably after the mixing step in that the radical polymerization can be easily controlled.

[0154] As the polymerization initiator, various known polymerization initiators are suitably used.Specific examples thereof include hydrogen peroxide, acetyl peroxide, cumyl peroxide, tert-butyl peroxide, propionyl peroxide, benzoyl peroxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, lauroyl peroxide, ammonium persulfate, sodium persulfate, potassium persulfate, diisopropyl peroxycarbonate, tetralin hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide, triphenylacetic acid tert-hydroperoxide, tert-butyl performate, and peracetic acid tert-hydroperoxide. Examples of suitable initiators include peroxides such as tert-butyl perbenzoate, tert-butyl perphenylacetate, tert-butyl permethoxyacetate, and tert-butyl per-N-(3-toluyl)palmitate; and azo compounds such as 2,2'-azobis(2-aminodipropane) hydrochloride, 2,2'-azobis(2-aminodipropane) nitrate, 1,1'-azobis(1-methylbutyronitrile-3-sodium sulfonate), 4,4'-azobis-4-cyanovaleric acid, and poly(tetraethylene glycol-2,2'-azobisisobutyrate). The amount of polymerization initiator added varies depending on the desired molecular weight and molecular weight distribution, but is preferably within the range of 0.1 to 5.0% by mass, for example, relative to the polymerizable monomer.

[0155] (7-2-5) Chain transfer agent In the polymerization process of the aromatic vinyl monomer and (meth)acrylic acid ester monomer, a commonly used chain transfer agent can be used to adjust the molecular weight of the styrene-acrylic polymer segment. Examples of the chain transfer agent include, but are not limited to, alkyl mercaptans and mercapto fatty acid esters.

[0156] The chain transfer agent is preferably mixed together with the resin-forming material in the above-mentioned mixing step.

[0157] The amount of chain transfer agent added varies depending on the molecular weight and molecular weight distribution of the desired styrene-acrylic polymer segment, but is preferably within the range of 0.1 to 5.0% by mass, for example, based on the total mass of the aromatic vinyl monomer, the (meth)acrylic acid ester monomer, and the bireactive monomer.

[0158] (8) Average long side length of the convex part The average long side length of the projections is preferably within a range of 100 to 500 nm, more preferably within a range of 100 to 300 nm, from the viewpoint of reducing adhesion to other members and improving filming resistance.

[0159] In the present invention, the long side length of a protrusion and the average long side length of the protrusions can be measured as follows. In image data taken at 10,000x magnification using a scanning electron microscope, the protrusions are visually confirmed, a contour line is drawn for each protrusion, and when this contour line is sandwiched between two parallel lines, the longest distance between the two parallel lines (X in Figure 2) is taken as the "long side length of the protrusion." This measurement is performed for 100 protrusions with a long side length in the range of 30 to 2,000 nm, and the average value is taken as the "average long side length of the protrusions."

[0160] (9) Average density distribution of convex parts The average density distribution of the convex parts is 20 to 50 pieces / μm 2 The range is preferably 25 to 45 particles / μm 2 This makes it possible to reduce the adhesion of the toner to other members, and also to more reliably prevent the toner particles from slipping through by catching the protrusions between the photoreceptor surface and the cleaning blade.

[0161] In the present invention, the density distribution of protrusions and the average density distribution of protrusions can be measured as follows. In image data taken at a magnification of 10,000 times using a scanning electron microscope, the number of protrusions with a long side length of 30 to 2,000 nm per unit surface area of ​​each toner base particle is defined as the "density distribution of protrusions." This measurement is performed on 20 protrusions with a long side length in the range of 30 to 2,000 nm, and the average value is defined as the "average density distribution of protrusions."

[0162] <2.3 Lubricant particles> The toner particles according to the present invention are characterized in that they contain at least one type of lubricant particle as an external additive, and the median diameter D2 of the lubricant particle with the smallest median diameter is equal to or greater than the average spacing D1 of the convex portions on the surface of the toner base particle.

[0163] As described above, "lubricant particles with the smallest median diameter" refers to lubricant particles of only one type if there is only one type of lubricant particle, and refers to lubricant particles of the type with the smallest median diameter if there are multiple types of lubricant particles.

[0164] The lubricant particles used in the present invention are preferably fatty acid metal salt particles. By using positively chargeable fatty acid metal salt particles as the lubricant particles, excessive charging of the toner is suppressed, and the electrostatic adhesion force between the toner particles and the photoreceptor is reduced, thereby further reducing the adhesion of toner-derived foreign matter to the photoreceptor.

[0165] The fatty acid metal salt constituting the fatty acid metal salt particles is preferably a salt of a metal selected from zinc, calcium, magnesium, aluminum, and lithium. Among these, fatty acid zinc, fatty acid lithium, and fatty acid magnesium are particularly preferred. Furthermore, the fatty acid of the fatty acid metal salt is preferably a higher fatty acid having 12 to 22 carbon atoms. Using a fatty acid having 12 or more carbon atoms can suppress the generation of free fatty acids, and a fatty acid having 22 or less carbon atoms can prevent the melting point of the fatty acid metal salt from becoming too high, thereby achieving good fixability. As the fatty acid, stearic acid is particularly preferred.

[0166] The fatty acid metal salt particles used in the present invention are preferably zinc stearate particles or aluminum stearate particles, and among these, zinc stearate particles are particularly preferred because of their small adhesive force to the toner base particles.

[0167] Furthermore, when fatty acid metal salt particles are used as the lubricant particles, it is preferable that the liberation rate R of fatty acid metal salt particles from toner base particles in the toner particles, determined by an ultrasonic treatment method under the following conditions, is within the range of 20 to 60%.

[0168] If the liberation rate R is 20% or higher, an appropriate amount of lubricant particles can be supplied onto the photoreceptor to reduce toner adhesion. Also, if the liberation rate is 60% or lower, extreme liberation of lubricant particles is suppressed, and excessive lubricant particles are not supplied onto the photoreceptor, thereby suppressing image defects such as lubricant memory.

[0169] [Conditions for ultrasonic treatment] Step 1: The net intensity W1 of the metal elements originating from the fatty acid metal salt particles in the toner particles is measured by X-ray fluorescence analysis. Step 2: Prepare an aqueous dispersion of toner particles. Step 3: The prepared aqueous dispersion is subjected to ultrasonic treatment. Step 4: The fatty acid metal salt particles liberated from the toner base particles by ultrasonic treatment are removed. Step 5: In the toner particles from which the liberated fatty acid metal salt particles have been removed, the net intensity W2 of the metal elements derived from the fatty acid metal salt particles is measured by fluorescent X-ray analysis. Step 6: Calculate the liberation rate R [%] using the following formula (2). Formula (2) R=(W1-W2) / W1×100

[0170] In steps 1 and 5, the NET intensities W1 and W2 of the metal elements derived from the fatty acid metal salt particles can be measured using, for example, an X-ray fluorescence analyzer "XRF-1700" (manufactured by Shimadzu Corporation). A specific method for measuring the NET intensity involves pelletizing 2 g of toner particles under a load of 15 t for 10 seconds, and then performing qualitative and quantitative analysis under the following conditions. The Kα peak angle of the element to be measured (the metal element derived from the fatty acid metal salt particles) can be determined and used from a 2θ table.

[0171] -Measurement conditions- Slit: Standard Attenuator: None Spectroscopic crystal (Ti=LiF, Si=PET) Detector (Ti=SC, Si=FPC)

[0172] In step 2, the aqueous dispersion of toner particles can be prepared by, for example, wetting 3 g of toner particles with 40 g of a 0.2% by mass aqueous solution of polyoxyethyl phenyl ether.

[0173] The ultrasonic treatment in step 3 can be carried out by using, for example, an ultrasonic homogenizer "US-1200" (manufactured by Nippon Kikai Co., Ltd.), adjusting the ultrasonic energy so that the value of the ammeter that shows the vibration indicator value attached to the main device indicates 60 μA (50 W), and applying the ultrasonic energy to the aqueous dispersion prepared in step 2 for 2 minutes.

[0174] In step 4, the fatty acid metal salt particles liberated from the toner base particles can be removed by, for example, filtering using a filter with 1 μm openings and washing with pure water.

[0175] As the lubricant particles, particles made of calcium fluoride, boron nitride, molybdenum disulfide, tungsten disulfide, talc, kaolin, montmorillonite, mica, etc. can be used in addition to fatty acid metal salt particles.

[0176] The content of the lubricant particles is not particularly limited, but is preferably in the range of 0.01 to 5.0% by mass, more preferably 0.05 to 2.0% by mass, based on the total amount of the toner base particles.

[0177] <2.4 Non-lubricant particles> The toner particles according to the present invention are characterized in that they contain at least one type of non-lubricant particle as an external additive, and the median diameter D3 of the non-lubricant particle having the largest median diameter is equal to or less than the average spacing D1 of the convex portions on the surface of the toner base particle.

[0178] As described above, "non-lubricant particles with the largest median diameter" refers to non-lubricant particles of only one type of non-lubricant particle, or to non-lubricant particles of the type with the largest median diameter among multiple types of non-lubricant particles.

[0179] As the non-lubricant particles, inorganic fine particles and organic fine particles exemplified below can be used.

[0180] Examples of inorganic fine particles include silica particles, titanium oxide particles, alumina particles, zirconia particles, zinc oxide particles, chromium oxide particles, cerium oxide particles, antimony oxide particles, tungsten oxide particles, tin oxide particles, tellurium oxide particles, manganese oxide particles, boron oxide particles, strontium titanate particles, etc. Among these, silica particles, titanium oxide particles, alumina particles, strontium titanate particles, etc. are preferred, and alumina particles are particularly preferred from the viewpoint of cost.

[0181] The surfaces of the inorganic fine particles are preferably hydrophobized, and a known surface treatment agent is used for the hydrophobization. Examples of the surface treatment agent include silane coupling agents, silicone oils, titanate coupling agents, aluminate coupling agents, fatty acids, fatty acid metal salts, esters thereof, and rosin acids. These surface treatment agents may be used alone or in combination.

[0182] Examples of the silane coupling agent include dimethyldimethoxysilane, hexamethyldisilazane (HMDS), methyltrimethoxysilane, isobutyltrimethoxysilane, decyltrimethoxysilane, etc. Examples of the silicone oil include cyclic compounds and linear or branched organosiloxanes, more specifically, organosiloxane oligomers, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, tetramethylcyclotetrasiloxane, tetravinyltetramethylcyclotetrasiloxane, etc.

[0183] As the organic fine particles, for example, organic fine particles containing homopolymers such as styrene and methyl methacrylate, or copolymers thereof can be used.

[0184] In the toner particles according to the present invention, it is preferable that at least one of the non-lubricant particles has a Mohs hardness of 8 or more. This increases the adhesive strength of the non-lubricant particles, which serve as the nucleus of deposits on the photoreceptor, to the toner base particles, reducing the amount of liberation, thereby further reducing deposits on the photoreceptor. As long as the Mohs hardness is 8 or more, there is no significant difference in the effect.

[0185] The Mohs hardness scale was invented by F. Mohs. The Mohs hardness of particles can be measured using a known Mohs hardness scale. Specifically, particles are compacted in a pressure molding machine to prepare pellets. The following ten minerals are rubbed against the prepared pellets in order. If a scratch is produced, the mineral is deemed to be harder than the mineral. The presence or absence of scratches is determined visually. The minerals are ranked in order of decreasing hardness: 1: talc, 2: gypsum, 3: calcite, 4: fluorite, 5: apatite, 6: orthoclase, 7: quartz, 8: topaz, 9: corundum, and 10: diamond. The Mohs hardness scale is rated in increments of 0.5. For example, a Mohs hardness of 7 indicates that both the pellet and quartz are scratched when rubbed against each other, and 7.5 indicates that only the quartz is scratched when rubbed against the pellet and the topaz, and only the pellet is scratched when rubbed against the target.

[0186] The content of the non-lubricant particles is not particularly limited, but is preferably in the range of 0.01 to 10.0% by mass, more preferably 0.05 to 5.0% by mass, based on the total amount of the toner base particles.

[0187] <2.5 Other parameters of toner particles> (Average circularity of toner particles) The average circularity of the toner particles is preferably within a range of, for example, 0.940 to 0.980.

[0188] The average circularity of the toner particles is the arithmetic mean value of the circularity obtained by adding up the circularity of each toner particle and dividing the sum by the total number of particles measured.

[0189] The circularity of toner particles can be measured using a flow particle image analyzer "FPIA-2100" (manufactured by Sysmex Corporation). Specifically, toner particles are wetted in a surfactant aqueous solution, ultrasonically dispersed for 1 minute, and then dispersed. Circularity is measured using the "FPIA-2100" in the HPF (high magnification imaging) mode under measurement conditions at an appropriate concentration within the HPF detection count range of 3,000 to 10,000 particles. Within this range, reproducible measurements can be obtained.

[0190] The circularity is calculated by the following formula: Circularity = (perimeter of a circle with the same projected area as the particle image) / (perimeter of the projected particle image)

[0191] (Toner particle size) The particle size of the toner particles is preferably, for example, within a range of 3 to 10 μm in terms of volume-based median diameter.

[0192] By setting the volume-based median diameter within the above range, it becomes possible to faithfully reproduce extremely fine dot images, for example, at a level of 1200 dpi.

[0193] The volume-based median diameter of the toner particles can be measured and calculated using, for example, a device in which a Coulter Multisizer 3 (manufactured by Beckman Coulter) is connected to a computer system for data processing.

[0194] The measurement procedure involves mixing 0.02 g of toner particles with 20 mL of surfactant solution (for example, a surfactant solution prepared by diluting a neutral detergent containing surfactant components 10 times with pure water to disperse the toner particles), followed by ultrasonic dispersion for 1 minute to prepare a toner particle dispersion. This toner particle dispersion is then pipetted into a beaker containing an ISOTON II (manufactured by Beckman Coulter) in a sample stand until the measurement concentration is within the range of 5-10% by mass, and the measurement is performed with the instrument count set to 25,000 particles. The Coulter Multisizer 3 has an aperture diameter of 100 μm. The measurement range of 1-30 μm is divided into 256 sections to calculate the frequency count, and the particle diameter with the largest 50% volume fraction is taken as the volume-based median diameter.

[0195] (Softening point of toner particles) The softening point Tsp of the toner particles is preferably, for example, within the range of 90 to 115° C. When the softening point Tsp of the toner is within this range, favorable low-temperature fixability can be obtained.

[0196] The softening point Tsp of the toner particles can be measured using a flow tester "CFT-500D" (manufactured by Shimadzu Corporation) in the same manner as the softening point Tsp of the resin for the toner base particle precursor described above.

[0197] 2.6 Toner manufacturing method The toner according to the present invention can be produced by producing toner base particles and then adding external additives thereto.

[0198] Examples of methods for producing toner base particles include suspension polymerization, emulsion aggregation, and other known methods, but the emulsion aggregation method is preferred, as it can easily reduce the particle size of toner particles from the standpoints of production cost and production stability.

[0199] The emulsion aggregation method is a method for producing toner base particles by mixing a dispersion of resin particles for toner base particle precursors, produced by emulsification, with a dispersion of colorant particles (hereinafter also referred to as "colorant particles") as needed, aggregating the particles to a desired particle size, and further controlling the shape by fusing the resin particles together. Here, the resin particles for toner base particle precursors may optionally contain a release agent, a charge control agent, etc.

[0200] A specific example of the production of the toner base particles according to the present invention by emulsion aggregation will be described below. First step: A step of preparing a resin dispersion for toner base particle precursors, a resin dispersion for convex portions, a colorant particle dispersion, etc. Second step: Forming toner base particle precursor Third step: forming convex portions on the surface of the toner base particle precursor 4th step: Washing and drying the toner base particles Fifth step: Adding external additives to the toner base particles

[0201] (1) First step In the first step, a resin dispersion for toner base particle precursors, a colorant dispersion, a resin dispersion for convex portions, and the like are prepared.

[0202] (1-1) Preparation of resin dispersion for toner base particle precursor A dispersion of resin particles for toner base particle precursors containing a resin for toner base particle precursors and, if necessary, a release agent is prepared.

[0203] The resin particle dispersion for toner base particle precursors can be prepared by emulsion polymerization in an aqueous medium.

[0204] The resin particles for toner base particle precursors may have a multilayer structure of two or more layers made of resins with different compositions. Resin particles with such a structure, for example, those having a two-layer structure, can be obtained by preparing a dispersion of resin particles by a conventional emulsion polymerization process (first-stage polymerization), adding a polymerization initiator and a polymerizable monomer to the dispersion, and polymerizing the system (second-stage polymerization). If necessary, a third-stage polymerization can be performed by adding a polymerizable monomer to form a three-layer structure.

[0205] The toner base particles according to the present invention may contain internal additives such as colorants, charge control agents, or magnetic powders, as needed. Such internal additives can be introduced into the toner base particles, for example, by dissolving or dispersing them in advance in a monomer solution for forming the toner base particle precursor resin in the polymerization step of the toner base particle precursor resin.

[0206] Furthermore, such internal additives can be introduced into the toner base particles by separately preparing a dispersion of internal additive particles consisting only of the internal additives, and aggregating the internal additive particles together with the resin particles for the toner base particle precursor and the colorant particles in the second step. However, it is preferable to adopt a method in which the internal additives are introduced in advance in the polymerization step of the resin for the toner base particle precursor.

[0207] The particle size of the resin particles for toner base particle precursor in the dispersion liquid is preferably such that the volume-based median diameter is within the range of 50 to 500 nm, since this allows the average long side length and average spacing of the convex portions to be controlled within the above-mentioned ranges. The volume-based median diameter can be measured using a Coulter Multisizer 3 (manufactured by Beckman Coulter, Inc.).

[0208] (1-2) Preparation of resin particle dispersion for convex portions Specific examples of methods for preparing a dispersion of resin particles for the protrusions include a method in which resin particles for the protrusions are pulverized by a mechanical method and then dispersed in an aqueous medium using a surfactant; a method in which a solution of the resin for the protrusions dissolved in an organic solvent is poured into an aqueous medium and dispersed therein to form an aqueous medium dispersion; a method in which the resin for the protrusions is mixed in a molten state with an aqueous medium and then mechanically dispersed to form an aqueous medium dispersion; and a phase inversion emulsification method. Any of these methods may be used in the present invention.

[0209] The particle size of the resin particles for the protrusions in the dispersion is preferably within a range of 50 to 500 nm in terms of volume-based median diameter, which can be measured using a Coulter Multisizer 3 (manufactured by Beckman Coulter, Inc.).

[0210] (1-3) Preparation of colorant particle dispersion When the toner base particles contain a colorant, a colorant particle dispersion is prepared. The colorant particle dispersion can be prepared by dispersing the colorant in an aqueous medium. The colorant dispersion is preferably carried out in an aqueous medium with a surfactant concentration equal to or higher than the critical micelle concentration (CMC), so that the colorant is uniformly dispersed. Various known dispersers can be used for the colorant dispersion.

[0211] The particle size of the colorant particles in the dispersion is preferably within a range of 10 to 300 nm in terms of volume-based median diameter, which can be measured using a Coulter Multisizer 3 (manufactured by Beckman Coulter, Inc.).

[0212] (2)Second process In the second step, toner base particle precursors are formed by aggregating resin particles contained in a dispersion of resin particles for toner base particle precursors.

[0213] In the second step, particles of other toner components such as a charge control agent and colorant particles may be aggregated into the resin particles for toner base particle precursors, if necessary. Therefore, in the second step, a colorant particle dispersion or the like may be mixed into the resin particle dispersion for toner base particle precursors, if necessary.

[0214] In the first step, the resin particle dispersion for the toner base particle precursor may contain a release agent. However, in the first step, the resin particles for the toner base particle precursor may not contain a release agent, and a release agent particle dispersion containing only a release agent may be separately prepared, and in the second step, the release agent particle dispersion may be mixed with the resin particle dispersion for the toner base particle precursor.

[0215] A specific method for forming a toner base particle precursor by aggregating resin particles contained in a dispersion of resin particles for a toner base particle precursor is not particularly limited, but may include a method in which an aggregating agent is added to an aqueous medium to a critical aggregation concentration or higher, and then the mixture is heated to a temperature that is higher than the glass transition point of the resin particles for a toner base particle precursor and lower than the melting peak temperature of the mixture, thereby promoting salting out of particles such as the resin particles for a toner base particle precursor and colorant particles and simultaneously promoting fusion.

[0216] In this method, it is preferable to keep the time left as short as possible after adding the aggregating agent and quickly heat the mixture to a temperature equal to or higher than the glass transition temperature Tg of the resin particles for toner base particle precursors and equal to or lower than the melting peak temperature of the mixture. The reason for this is not clear, but it is because there is a concern that depending on the time left after salting out, the aggregation state of the particles may fluctuate, causing unstable particle size distribution or changing the surface properties of the fused particles.

[0217] The time until the temperature rise starts is usually preferably within 30 minutes. The temperature rise rate is preferably 1°C / min or more. While there is no particular upper limit to the temperature rise rate, it is preferably 10°C / min or less in order to prevent the generation of coarse particles due to rapid fusion. Furthermore, after the reaction system reaches a temperature equal to or higher than the glass transition point, it is important to maintain the temperature of the reaction system for a certain period of time to allow fusion to continue. This effectively promotes the growth and fusion of the toner base particle precursors, thereby improving the durability of the final toner particles.

[0218] The toner base particle precursor is preferably produced by aggregating and fusing crystalline polyester resin particles and amorphous resin particles in the presence of metal ions. The crystalline polyester resin can effectively exhibit low-temperature fixability by being finely dispersed within the toner. Furthermore, it is preferable that the crystalline polyester resin is not present on the surface of the toner base particle precursor or the surface of the toner base particles. Therefore, it is preferable that the crystalline polyester resin is added before or after the addition of an aggregating agent, or when the reaction system reaches a desired temperature, before the toner base particle precursor grows.

[0219] The flocculant used in the second step is not particularly limited, but is preferably selected from metal salts. Examples of metal salts include monovalent metal salts such as salts of alkali metals such as sodium, potassium, and lithium; divalent metal salts such as calcium, magnesium, manganese, and copper; and trivalent metal salts such as iron and aluminum. Specific metal salts include sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, zinc chloride, copper sulfate, magnesium sulfate, and manganese sulfate. Among these, divalent metal salts are particularly preferred because they can promote flocculation with smaller amounts. These can be used alone or in combination of two or more.

[0220] The particle size of the toner base particle precursor obtained in the second step is, for example, preferably in the range of 3 to 10 μm, more preferably 4 to 7 μm, in terms of volumetric median diameter. The volumetric median diameter can be measured using a Coulter Multisizer 3 (manufactured by Beckman Coulter, Inc.).

[0221] (3) Third step In the third step, convex portions are formed on the surface of the toner base particle precursor.

[0222] Specifically, the projection resin particle dispersion is added to an aqueous medium (reaction liquid) of the toner base particle precursors grown to the desired particle diameter in the second step, and the projection resin particles are adhered to the toner base particle precursors. After that, the pH of the aqueous medium (reaction liquid) is adjusted with a pH adjuster to fuse the particles.

[0223] Specifically, the method involves first adding an aggregating agent to an aqueous medium to a concentration equal to or higher than the critical aggregating concentration, and then heating the mixture to a temperature equal to or higher than the glass transition temperature Tg of the resin particles for the convex portions and equal to or lower than the melting peak temperature of the mixture.

[0224] Next, when the supernatant of the aqueous medium becomes transparent, an aggregation terminator is added to stop particle growth, and the temperature is then raised to a temperature in the range of 80 to 90°C while stirring.

[0225] This allows a plurality of convex portions to be formed on the surface of the toner base particle precursor, thereby forming toner base particles. Next, by cooling to a range of 20 to 30°C, a dispersion of toner base particles having convex portions on the surface of the toner base particle precursor is obtained.

[0226] In the third step, the fusion time for fusing the resin for the convex portions to the toner base particle precursor is preferably within a range of 10 to 180 minutes, and more preferably within a range of 30 to 120 minutes, since this allows the average long side length and average spacing of the convex portions to be controlled within the above-mentioned ranges.

[0227] (4) 4th step In the fourth step, the toner base particles are washed and dried. The washing and drying of the toner base particles can be performed using various known methods. That is, the dispersion of the toner base particles is subjected to solid-liquid separation using a known method such as a centrifuge, followed by washing, and the organic solvent is removed by drying under reduced pressure. Furthermore, moisture and traces of organic solvent are removed using a known drying device such as a flash jet dryer or a fluidized bed dryer. The drying temperature may be within a range in which the toner does not fuse.

[0228] (5) Fifth step In the fifth step, external additives are added to the toner base particles. Specifically, the external additives are added to the dried toner base particles and mixed to form toner particles. In the present invention, at least one type of lubricant particle and at least one type of non-lubricant particle are used as the external additives.

[0229] The external additives can be added in the form of powder to dried toner base particles by a dry method, and the mixing device can be a mechanical mixer such as a Henschel mixer or a coffee mill.

[0230] <2.7 Developer> The toner according to the present invention can be used as a magnetic or non-magnetic one-component developer, but may also be mixed with a carrier and used as a two-component developer.

[0231] The carrier may be magnetic particles made of a conventionally known material such as a metal such as iron, ferrite, or magnetite, or an alloy of such a metal with a metal such as aluminum or lead, and among these, ferrite particles are preferred. Alternatively, the carrier may be a coated carrier in which the surface of magnetic particles is coated with a coating agent such as a resin, or a resin-dispersed carrier in which magnetic fine powder is dispersed in a binder resin.

[0232] The carrier preferably has a volume average particle size in the range of 15 to 100 μm, more preferably in the range of 25 to 80 μm.

[0233] <3 Organic photoreceptor> The organic photoreceptor used in the image forming system of the present invention is characterized by having a protective layer containing a cured resin.

[0234] The structure of the organic photoreceptor according to the present invention is not particularly limited as long as it has a protective layer containing a cured resin. For example, it may have a structure in which an intermediate layer is formed on a conductive support, a photosensitive layer is formed on the intermediate layer, and a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material are laminated in this order, and a protective layer is formed on the photosensitive layer as the outermost layer. The photosensitive layer may have a single layer structure containing a charge generation material and a charge transport material. An organic photoreceptor having such a structure will be described in detail below.

[0235] 3.1 Conductive support The conductive support is a member that supports the photosensitive layer and has conductivity. Preferred examples of the conductive support include a metal drum or sheet, a plastic film with a laminated metal foil, a plastic film with a vapor-deposited conductive material film, a metal member or plastic film with a conductive layer coated with a conductive material or a paint containing a conductive material and a binder resin, and paper. Preferred examples of the metal include aluminum, copper, chromium, nickel, zinc, and stainless steel, and preferred examples of the conductive material include the above metals, indium oxide, and tin oxide.

[0236] <3.2 Photosensitive layer> The photosensitive layer is a layer for forming a desired electrostatic latent image on the surface of a photoreceptor by exposure. The photosensitive layer may be a single layer or may be composed of multiple laminated layers. Preferred examples of the photosensitive layer include a single layer containing a charge transport material and a charge generation material, and a laminate of a charge transport layer containing a charge transport material and a charge generation layer containing a charge generation material.

[0237] <3.3 Protective layer> The protective layer is characterized by containing a cured resin, which improves the mechanical strength of the photoreceptor surface and improves scratch resistance and abrasion resistance.

[0238] (1) Cured resin The "cured resin" contained in the protective layer refers to a compound in which a polymerizable monomer is polymerized (cured) by irradiation with active energy rays such as ultraviolet rays, visible light, or electron beams, or by application of energy such as heating.

[0239] The type of polymerizable group possessed by the polymerizable monomer that is cured to become a cured resin is not particularly limited, but a radically polymerizable group is preferred. Here, the radically polymerizable group refers to a radically polymerizable group having a carbon-carbon double bond. Examples of the radically polymerizable group include a vinyl group and a (meth)acryloyl group, and a (meth)acryloyl group is preferred. When the polymerizable group is a (meth)acryloyl group, the abrasion resistance and fogging suppression effect of the protective layer are improved. The reason for the improved abrasion resistance of the protective layer is presumed to be that efficient curing is possible with a small amount of light or in a short time.

[0240] Examples of polymerizable monomers that are cured to form cured resins include styrene-based monomers, (meth)acrylic-based monomers, vinyltoluene-based monomers, vinyl acetate-based monomers, N-vinylpyrrolidone-based monomers, etc. These polymerizable monomers can be used alone or in combination of two or more.

[0241] The number of polymerizable groups in one molecule of the polymerizable monomer is not particularly limited, but is preferably 2 or more, and more preferably 3 or more. Within this range, the abrasion resistance of the protective layer is improved. This is presumably because the crosslink density of the protective layer increases, further improving film strength. Furthermore, the number of polymerizable groups in one molecule of the polymerizable monomer is not particularly limited, but is preferably 6 or less, more preferably 5 or less, and even more preferably 4 or less. Within this range, the uniformity of the protective layer is improved, and the fogging suppression effect is improved. This is presumably because the crosslink density is below a certain level, making cure shrinkage less likely to occur. From these perspectives, the number of polymerizable groups in one molecule of the polymerizable monomer is most preferably 3.

[0242] Specific examples of the polymerizable monomer include, but are not limited to, the following compounds M1 to M11, of which the following compound M2 is particularly preferred: In each of the following formulas, R represents an acryloyl group (CH2=CHCO-), and R' represents a methacryloyl group (CH2=C(CH3)CO-).

[0243] [ka]

[0244] Furthermore, a charge transport compound having a polymerizable group can be used as the polymerizable monomer that forms the cured resin contained in the protective layer, thereby improving the abrasion resistance of the organic photoreceptor and also improving the charge transport properties.

[0245] Examples of charge transport compounds having a polymerizable group include compounds having a charge transport structure as a basic skeleton, such as triarylamine derivatives, carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl derivatives, hydrazone derivatives, pyrazoline derivatives, oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, phenylenediamine derivatives, stilbene derivatives, and benzidine derivatives, and having the above-mentioned radical polymerizable group as a polymerizable group. Among these, compounds having a triarylamine derivative as a basic skeleton and a (meth)acryloyl group as a polymerizable group are preferred.

[0246] The polymerizable monomers may be used alone or in combination of two or more kinds. The polymerizable monomers may be synthetic products or commercially available products.

[0247] (2) Metal oxide particles The protective layer preferably contains metal oxide particles, which inhibits wear and further improves durability.

[0248] In the present invention, the term "metal oxide particles" refers to particles whose surface is at least composed of a metal oxide. Examples of metal oxides constituting metal oxide particles include, but are not limited to, silicon oxide (silica), tin oxide, alumina, magnesium oxide, zinc oxide, lead oxide, tantalum oxide, indium oxide, bismuth oxide, yttrium oxide, cobalt oxide, copper oxide, manganese oxide, selenium oxide, iron oxide, zirconium oxide, germanium oxide, titanium oxide, niobium oxide, molybdenum oxide, vanadium oxide, copper aluminum oxide, and tin oxide doped with antimony ions. These metal oxide particles can be used alone or in combination of two or more. Furthermore, the metal oxide particles may be synthetic or commercially available.

[0249] Among these, silicon oxide particles and tin oxide particles are more preferred, and silicon oxide particles are even more preferred.

[0250] The number-average primary particle diameter of the metal oxide particles is preferably within a range of 50 to 500 nm, more preferably within a range of 65 to 400 nm, and even more preferably within a range of 80 to 300 nm. When the number-average primary particle diameter of the metal oxide particles is 50 nm or more, the metal oxide particles provide appropriate unevenness, which stabilizes the position of the cleaning blade during cleaning and improves cleaning performance. Furthermore, when the number-average primary particle diameter of the metal oxide particles is 500 nm or less, the protrusions are too large to be caught by the cleaning blade, which reduces the risk of deterioration in cleaning performance due to blade stick-slip.

[0251] The number average primary particle size of the metal oxide particles is defined as the number average primary particle size measured by the following method.

[0252] First, a 10,000x magnified photograph taken with a scanning electron microscope (manufactured by JEOL Ltd.) was scanned. Next, 300 particle images, excluding aggregated particles, were randomly selected from the resulting photograph and binarized using an automatic image processing and analysis system, Luzex® AP Software Ver. 1.32 (manufactured by Nireco Corporation), to calculate the horizontal Feret diameter of each particle image. The average value of the horizontal Feret diameters of each particle image was then calculated to obtain the number-average primary particle diameter. Here, the horizontal Feret diameter refers to the length of the side parallel to the x-axis of the circumscribing rectangle obtained when the particle image is binarized. Furthermore, the measurement of the number-average primary particle diameter of metal oxide particles is performed on metal oxide particles that do not contain chemical species (coating layers) derived from the surface treatment agent.

[0253] The metal oxide particles are preferably surface-treated with a surface treatment agent. The metal oxide particles surface-treated with the surface treatment agent are considered to be coated particles containing chemical species (coating layer) derived from the surface treatment agent and metal oxide particles. The surface-treated metal oxide particles only need to have chemical species (coating layer) derived from the surface treatment agent on at least a portion of their surface.

[0254] The surface treatment agent is not particularly limited, but examples thereof include a silicone surface treatment agent having a silicone chain and a surface treatment agent having a polymerizable functional group, and a surface treatment agent having a silicone chain (hereinafter often referred to as a silicone surface treatment agent) is preferred.

[0255] The silicone surface treatment agent is not particularly limited, but is preferably one having a silicone chain in a side chain of the polymer main chain, and more preferably one having a reactive functional group. The reactive functional group may be a carboxy group, a hydroxy group, or an -R d -COOH(R d is a divalent hydrocarbon group), alkylsilyl group, halogenated silyl group, alkoxysilyl group, etc. Among these, a carboxy group, a hydroxy group, or an alkoxysilyl group is preferred.

[0256] The polymer main chain of the silicone surface treatment agent is preferably a poly(meth)acrylate main chain or a silicone main chain, and more preferably a silicone main chain. Metal oxide particles surface-treated with a surface treatment agent having silicone chains in both the main chain and side chains have more silicone chains, which improves dispersibility in the protective layer and further improves the abrasion resistance of the protective layer.

[0257] The side chain and main chain silicone chains preferably have a dimethylsiloxane structure as a repeating unit, and the number of repeating units is preferably 3 to 100, more preferably 3 to 50, and even more preferably 3 to 30.

[0258] The weight average molecular weight of the silicone surface treatment agent is not particularly limited, but is preferably within the range of 1000 to 50000. The weight average molecular weight of the silicone surface treatment agent can be measured by gel permeation chromatography (GPC).

[0259] Silicone surface treatment agents can be used alone or in combination of two or more. Silicone surface treatment agents may be synthetic or commercially available. Specific examples of commercially available surface treatment agents having a silicone chain in a side chain of a poly(meth)acrylate main chain include SIMAC (registered trademark) US-350 (manufactured by Toagosei Co., Ltd.), KP-541, KP-574, and KP-578 (manufactured by Shin-Etsu Chemical Co., Ltd.). Specific examples of commercially available surface treatment agents having a silicone chain in a side chain of a silicone main chain include KF-9908 and KF-9909 (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0260] Furthermore, the above-mentioned metal oxide particles are preferably particles (composite particles) having a core-shell structure, which has a core made of a metal oxide and an outer shell made of a surface treatment agent. Increasing the particle size of a single particle without a core-shell structure increases the difference in refractive index between the polymerizable monomer and the particle, reducing the transmittance of the active energy rays (especially ultraviolet rays) used to cure the protective layer. As a result, the film strength of the cured protective layer may be insufficient. Therefore, by providing a core material, it is possible to reduce the sea area by improving dispersibility and ensure film strength by improving light transmittance.

[0261] The material constituting the core of the composite particles is not particularly limited, but examples thereof include barium sulfate, alumina, and silicon oxide. Among these, particles having barium sulfate as the core are preferred from the viewpoint of ensuring the light transmittance of the protective layer. The material constituting the outer shell of the composite particles is the same as the examples of metal oxides constituting the metal oxide particles. A preferred example of a core-shell structure composite particle is a composite particle having a core made of barium sulfate and an outer shell made of tin oxide. The ratio of the number average primary particle diameter of the core to the thickness of the outer shell may be appropriately set depending on the types of core and outer shell used and the combination thereof.

[0262] The surface treatment method using the surface treatment agent is not particularly limited, and any method can be used as long as it can adhere (or bond) the surface treatment agent to the surface of the metal oxide particles. Such methods are generally broadly divided into two types: wet treatment methods and dry treatment methods, and either method may be used.

[0263] When metal oxide particles are subjected to a surface treatment after the reactive surface treatment described below, the surface treatment agent adheres to (or bonds with) the surface of the metal oxide particles or the reactive surface treatment agent.

[0264] The wet treatment method is a method in which metal oxide particles and a surface treatment agent are dispersed in a solvent, thereby adhering (or bonding) the surface treatment agent to the surface of the metal oxide particles. A preferred method involves dispersing metal oxide particles and a surface treatment agent in a solvent, drying the resulting dispersion, and removing the solvent. A more preferred method involves further heat treatment, which causes the surface treatment agent to react with the metal oxide particles, thereby adhering (or bonding) the surface treatment agent to the surface of the metal oxide particles. Alternatively, after dispersing the surface treatment agent and the metal oxide particles in a solvent, the resulting dispersion may be wet-pulverized to simultaneously refine the metal oxide particles and advance the surface treatment.

[0265] The means for dispersing the metal oxide particles and the surface treatment agent in the solvent is not particularly limited and any known means can be used, and examples thereof include common dispersing means such as a homogenizer, a ball mill, and a sand mill.

[0266] The solvent is not particularly limited and any known solvent can be used, and preferred examples thereof include alcohol-based solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol (2-butanol), tert-butanol, and benzyl alcohol, and aromatic hydrocarbon-based solvents such as toluene and xylene. These may be used alone or in combination of two or more. Among these, methanol, 2-butanol, toluene, and a mixed solvent of 2-butanol and toluene are more preferred.

[0267] The dispersion time is not particularly limited, but is preferably within the range of 1 to 600 minutes, more preferably within the range of 10 to 360 minutes, and even more preferably within the range of 30 to 120 minutes.

[0268] The method for removing the solvent is not particularly limited and any known method can be used, examples of which include a method using an evaporator and a method of volatilizing the solvent at room temperature.

[0269] The heating temperature is not particularly limited, but is preferably in the range of 50 to 250°C, more preferably in the range of 70 to 200°C, and even more preferably in the range of 90 to 150°C. The heating time is not particularly limited, but is preferably in the range of 1 to 600 minutes, more preferably in the range of 10 to 300 minutes, and even more preferably in the range of 30 to 90 minutes. The heating method is not particularly limited, and known methods can be used.

[0270] The dry treatment method is a method in which a surface treatment agent is mixed with metal oxide particles and kneaded without using a solvent, thereby adhering (or bonding) the surface treatment agent to the surface of the conductive metal oxide. This method may involve mixing and kneading the surface treatment agent with the metal oxide particles, followed by a heat treatment to react the surface treatment agent with the metal oxide particles, thereby adhering (or bonding) the surface treatment agent to the surface of the metal oxide particles. Furthermore, when mixing and kneading the metal oxide particles with the surface treatment agent, the mixture may be dry-pulverized to simultaneously refine the metal oxide particles and advance the surface treatment.

[0271] The amount of the surface treatment agent used is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 2 parts by mass or more, relative to 100 parts by mass of the metal oxide particles before treatment (in the case of surface-treating metal oxide particles after a reactive surface treatment described below, the metal oxide particles after the reactive surface treatment). Within this range, the abrasion resistance and fogging suppression effect of the protective layer are further improved.

[0272] The amount of the surface treatment agent used is preferably 100 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 5 parts by mass or less, relative to 100 parts by mass of the metal oxide particles before surface treatment (or, in the case of surface-treating metal oxide particles after a reactive surface treatment described below, the metal oxide particles after the reactive surface treatment). Within this range, a decrease in the film strength of the protective layer due to unreacted surface treatment agent is suppressed, and the abrasion resistance of the protective layer is improved.

[0273] The surface treatment of untreated metal oxide particles or reactively surface-treated metal oxide particles can be confirmed by thermogravimetry / differential thermal analysis (TG / DTA) measurements, observation with a scanning electron microscope (SEM) or a transmission electron microscope (TEM), analysis with energy dispersive X-ray spectroscopy (EDX), etc.

[0274] The surface-treated particles preferably have groups derived from polymerizable groups. The abrasion resistance of the protective layer is improved by the surface-treated particles having groups derived from polymerizable groups. This is presumably because, in the cured product constituting the protective layer, the surface-treated particles and the polymerizable monomer are chemically bonded to each other, thereby improving the film strength of the protective layer. The type of polymerizable group is not particularly limited, but a radically polymerizable group is preferred. The method for introducing the polymerizable group is not particularly limited, but a method in which the metal oxide particles are surface-treated with a surface treatment agent having a polymerizable group is preferred.

[0275] The presence of polymerizable groups in the surface-treated particles and the presence of groups derived from polymerizable groups in the surface-treated particles in the protective layer can be confirmed by thermogravimetry / differential thermal analysis (TG / DTA) measurement, observation with a scanning electron microscope (SEM) or a transmission electron microscope (TEM), analysis with energy dispersive X-ray spectroscopy (EDX), mass spectrometry, etc.

[0276] The metal oxide particles that have been subjected to the above-mentioned surface treatment (silicone surface treatment) are preferably further surface-treated with a reactive surface treatment agent. Polymerizable groups are supported on the surface of the metal oxide particles by the reactive surface treatment, and as a result, the surface-treated particles further have polymerizable groups. Then, in the protective layer, the surface-treated particles are polymerized with polymerizable monomers via the polymerizable groups, forming a protective layer with higher film strength and further improving the abrasion resistance of the protective layer. At this time, the silicone surface-treated particles exist in the protective layer as a structure having groups derived from the polymerizable groups.

[0277] The reactive surface treatment agent has a polymerizable group and a reactive functional group. The type of polymerizable group is not particularly limited, but a radically polymerizable group is preferred. Here, the radically polymerizable group refers to a radically polymerizable group having a carbon-carbon double bond. Examples of the radically polymerizable group include a vinyl group and a (meth)acryloyl group, and among these, a methacryloyl group is preferred. Furthermore, the reactive functional group refers to a group that is reactive with polar groups, such as hydroxy groups, present on the surface of metal oxide particles. Examples of the reactive functional group include a carboxy group, a hydroxy group, -R'-COOH (R' is a divalent hydrocarbon group), an alkylsilyl group, a halogenated silyl group, and an alkoxysilyl group, and among these, an alkylsilyl group, a halogenated silyl group, and an alkoxysilyl group are preferred.

[0278] The reactive surface treatment agent is preferably a silane coupling agent having a radical polymerizable group, and examples thereof include compounds represented by the following formulas S-1 to S-32. S-1: CH2=CHSi(CH3)(OCH3)2 S-2: CH2=CHSi(OCH3)3 S-3: CH2=CHSiCl3 S-4: CH2=CHCOO(CH2)2Si(CH3)(OCH3)2 S-5: CH2=CHCOO(CH2)2Si(OCH3)3 S-6: CH2=CHCOO(CH2)2Si(OC2H5)(OCH3)2 S-7: CH2=CHCOO(CH2)3Si(OCH3)3 S-8: CH2=CHCOO(CH2)2Si(CH3)Cl2 S-9: CH2=CHCOO(CH2)2SiCl3 S-10: CH2=CHCOO(CH2)3Si(CH3)Cl2 S-11: CH2=CHCOO(CH2)3SiCl3 S-12: CH2=C(CH3)COO(CH2)2Si(CH3)(OCH3)2 S-13: CH2=C(CH3)COO(CH2)2Si(OCH3)3 S-14: CH2=C(CH3)COO(CH2)3Si(CH3)(OCH3)2 S-15: CH2=C(CH3)COO(CH2)3Si(OCH3)3 S-16: CH2=C(CH3)COO(CH2)2Si(CH3)Cl2 S-17: CH2=C(CH3)COO(CH2)2SiCl3 S-18: CH2=C(CH3)COO(CH2)3Si(CH3)Cl2 S-19: CH2=C(CH3)COO(CH2)3SiCl3 S-20: CH2=CHSi(C2H5)(OCH3)2 S-21: CH2=C(CH3)Si(OCH3)3 S-22: CH2=C(CH3)Si(OC2H5)3 S-23: CH2=CHSi(OCH3)3 S-24: CH2=C(CH3)Si(CH3)(OCH3)2 S-25: CH2=CHSi(CH3)Cl2 S-26: CH2=CHCOOSi(OCH3)3 S-27: CH2=CHCOOSi(OC2H5)3 S-28: CH2=C(CH3)COOSi(OCH3)3 S-29: CH2=C(CH3)COOSi(OC2H5)3 S-30: CH2=C(CH3)COO(CH2)3Si(OC2H5)3 S-31: CH2=CHCOO(CH2)2Si(CH3)2(OCH3) S-32: CH2=C(CH3)COO(CH2)8Si(OCH3)3

[0279] The reactive surface treatment agent may be used alone or in combination of two or more. The reactive surface treatment agent may be a synthetic product or a commercially available product. Specific examples of commercially available products include KBM-502, KBM-503, KBE-502, KBE-503, and KBM-5103 (all manufactured by Shin-Etsu Chemical Co., Ltd.).

[0280] When both silicone surface treatment and reactive surface treatment are performed, it is preferable to perform the silicone surface treatment after the reactive surface treatment. By performing the surface treatments in this order, the abrasion resistance of the protective layer is further improved. The reason for this is that the silicone chains, which have an oil-repellent effect, do not prevent the reactive surface treatment agent from contacting the metal oxide particle surface, so that the introduction of polymerizable groups into the metal oxide particles is more efficient.

[0281] The reactive surface treatment method is not particularly limited, and the same method as that described for the silicone surface treatment can be used, except that a reactive surface treatment agent is used. Also, known surface treatment techniques for metal oxide particles may be used.

[0282] When reactive surface treatment is carried out by a wet treatment method, the solvent is preferably methanol, ethanol or toluene, more preferably methanol or toluene.

[0283] The amount of reactive surface treatment agent used is preferably 0.5 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 1.5 parts by mass or more, relative to 100 parts by mass of metal oxide particles before reactive surface treatment. This range further improves the abrasion resistance and fogging suppression effect of the protective layer. Furthermore, the amount of reactive surface treatment agent used is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less, relative to 100 parts by mass of metal oxide particles before treatment. This range is a more appropriate range, avoiding an excessive amount of reactive surface treatment agent relative to the number of hydroxy groups on the particle surface. This prevents a decrease in the film strength of the protective layer due to unreacted reactive surface treatment agent, and further improves the abrasion resistance of the protective layer.

[0284] (3) Charge transport material From the viewpoint of the charge transporting property of the organic photoreceptor, the protective layer preferably contains a charge transporting material.

[0285] The charge transport material is not particularly limited, and known materials can be used. Examples include carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline compounds, oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, and benzidine derivatives. Among these, triarylamine derivatives are preferred. As the triarylamine derivative, those having a structure represented by the following general formula (1) are preferred.

[0286] [ka]

[0287] In the general formula (1), R1, R2, R3, and R4 each independently represent an alkyl group having 1 to 7 carbon atoms or an alkoxy group having 1 to 7 carbon atoms. k, l, and n each independently represent an integer of 0 to 5, and m represents an integer of 0 to 4. However, when k, l, m, or n is 2 or greater, multiple R1, R2, R3, and R4 may be the same or different. Among these, it is preferable that R1, R2, R3, and R4 each independently represent an alkyl group having 1 to 3 carbon atoms. It is also preferable that k, l, m, and n each independently represent an integer of 0 to 1.

[0288] As the compound having the structure represented by the above general formula (1), for example, those described in JP-A-2015-114454 can be used, and the compound can also be synthesized by known synthesis methods, such as the method disclosed in JP-A-2006-143720.

[0289] (4) Other ingredients The protective layer may further contain other components in addition to the above components. Examples of other components include, but are not limited to, lubricants. The lubricant is not particularly limited and known lubricants can be used, examples of which include polymerizable silicone compounds and polymerizable perfluoropolyether compounds.

[0290] 3.4 Manufacturing method of organic photoreceptor The method for producing the organic photoreceptor is not particularly limited, and the organic photoreceptor can be produced by a known method.

[0291] Among these, it is preferable to manufacture the protective layer by a method including the steps of applying a coating liquid containing a resin composition for forming a protective layer to the surface of a photosensitive layer formed on a conductive support, and irradiating the applied resin composition for forming a protective layer with active energy rays or heating the applied resin composition for forming a protective layer to obtain a cured product of the resin composition for forming a protective layer.

[0292] The resin composition for forming the protective layer contains, for example, a polymerizable monomer and a polymerization initiator for forming a cured resin, and may further contain metal oxide particles, a charge transport material, etc. The resin composition for forming the protective layer may also contain a dispersion medium.

[0293] The polymerization initiator is used to polymerize a polymerizable monomer. The polymerization initiator may be a thermal polymerization initiator or a photopolymerization initiator, but is preferably a photopolymerization initiator. Furthermore, when the polymerizable monomer is a radically polymerizable monomer, a radical polymerization initiator is preferably used. The radical polymerization initiator is not particularly limited and known initiators can be used, examples of which include alkylphenone compounds and phosphine oxide compounds. Among these, compounds having an α-aminoalkylphenone structure or an acylphosphine oxide structure are preferred, and compounds having an acylphosphine oxide structure are more preferred. An example of a compound having an acylphosphine oxide structure is IRGACURE® 819 (bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide) (manufactured by BASF Japan Ltd.). The polymerization initiators may be used alone or in combination of two or more.

[0294] Any dispersion medium can be used in the resin composition for forming the protective layer as long as it can dissolve or disperse polymerizable monomers, etc. Specific examples include methanol, ethanol, n-propanol, isopropanol, n-butanol, 2-butanol (sec-butanol), tert-butanol, benzyl alcohol, toluene, xylene, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1,3-dioxane, 1,3-dioxolane, pyridine, and diethylamine. The dispersion medium can be used alone or in combination of two or more.

[0295] The content of the dispersion medium relative to the total mass of the resin composition for forming the protective layer is not particularly limited, but is preferably in the range of 1 to 99 mass%, more preferably in the range of 40 to 90 mass%, and even more preferably in the range of 50 to 80 mass%.

[0296] The content of the polymerizable monomer in the resin composition for forming the protective layer is not particularly limited, but is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more. Within this range, the crosslink density of the protective layer increases, and the abrasion resistance of the protective layer is further improved. Furthermore, the content of the polymerizable monomer in the resin composition for forming the protective layer is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less.

[0297] The content of metal oxide particles in the resin composition for forming the protective layer is not particularly limited, but is preferably 20% by mass or more, more preferably 30% by mass or more, and even more preferably 40% by mass or more. Within this range, the crosslink density of the protective layer increases, the mechanical strength is further improved, and the abrasion resistance of the protective layer is further improved. Furthermore, the content of metal oxide particles in the resin composition for forming the protective layer is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less.

[0298] The content of the polymerization initiator in the resin composition for forming the protective layer is not particularly limited, but is preferably 0.1 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 5 parts by mass or more, relative to 100 parts by mass of the polymerizable monomer. Within this range, the abrasion resistance of the protective layer is improved. Within this range, the crosslink density of the protective layer is increased, the mechanical strength is further improved, and the abrasion resistance of the protective layer is further improved. Furthermore, the content of the polymerization initiator in the resin composition for forming the protective layer is preferably 40 parts by mass or less, more preferably 30 parts by mass or less, and even more preferably 20 parts by mass or less, relative to 100 parts by mass of the polymerizable monomer.

[0299] The method for preparing the resin composition for forming the protective layer is not particularly limited, and components such as polymerizable monomers may be added to a dispersion medium and stirred and mixed until dissolved or dispersed.

[0300] The protective layer of the organic photoreceptor according to the present invention can be formed by applying the resin composition for forming the protective layer prepared by the above-described method onto the photosensitive layer, followed by drying and curing.

[0301] During the above-mentioned coating, drying, and curing processes, reactions between polymerizable monomers, reactions between polymerizable monomers and reactive surface-treated metal oxide particles, reactions between reactive surface-treated metal oxide particles, etc. progress, and a protective layer containing a cured product of the resin composition for forming the protective layer is formed.

[0302] The method for applying the resin composition for forming the protective layer is not particularly limited, and known methods such as dip coating, spray coating, spinner coating, bead coating, blade coating, beam coating, slide hopper coating, and circular slide hopper coating can be used.

[0303] After the coating liquid is applied, the coating is dried naturally or by heating to form a coating film, which is then cured by irradiating it with active energy rays, preferably ultraviolet rays or electron beams, and more preferably ultraviolet rays.

[0304] Any light source that generates ultraviolet light can be used without limitation as the ultraviolet light source. For example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, a flash (pulse) xenon lamp, etc. can be used. The irradiation conditions vary depending on the lamp, but the irradiation amount (cumulative light amount) of ultraviolet light is preferably 5 to 5000 mJ / cm. 2 and more preferably 10 to 2000 mJ / cm 2 The irradiance of the ultraviolet light is preferably 5 to 500 mW / cm. 2 and more preferably 10 to 100 mW / cm 2 is.

[0305] The irradiation time for obtaining the required irradiation amount (accumulated light amount) of active energy rays is preferably 0.1 seconds to 10 minutes, and more preferably 0.1 seconds to 5 minutes from the viewpoint of work efficiency.

[0306] In the process of forming the protective layer, drying can be carried out before, after, or during irradiation with active energy rays, and the timing of drying can be appropriately selected by combining these.

[0307] Drying conditions can be appropriately selected depending on the type of solvent, thickness, etc. The drying temperature is preferably within the range of 20 to 180°C, more preferably within the range of 80 to 140°C, and the drying time is preferably within the range of 1 to 200 minutes, more preferably within the range of 5 to 100 minutes.

[0308] The thickness of the protective layer is preferably in the range of 1 to 10 μm, more preferably in the range of 1.5 to 5 μm.

[0309] The components contained in the protective layer can be confirmed by known analytical methods such as pyrolysis GC-MS, nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), and elemental analysis.

[0310] <4 Image forming device> As described above, in the image forming system of the present invention, the device section is particularly referred to as the "image forming device."

[0311] Fig. 3 is a cross-sectional view illustrating an example of the configuration of an image forming apparatus according to the present invention, and Fig. 4 is a cross-sectional view illustrating an example of the configuration of a main part of the image forming apparatus according to the present invention.

[0312] The image forming apparatus 100 shown in FIG. 3 is called a tandem color image forming apparatus, and has four sets of image forming units 110Y, 110M, 110C, and 110Bk, a paper feeding and conveying means 150, and a fixing means 170.

[0313] An original image reading device SC is disposed on the upper part of the main body of the image forming apparatus 100.

[0314] The image forming units 110Y, 110M, 110C, and 110Bk are arranged side by side in the vertical direction.

[0315] The image forming units 110Y, 110M, 110C, and 110Bk each include a rotating drum-shaped organic photoreceptor 111Y, 111M, 111C, and 111Bk, charging means 113Y, 113M, 113C, and 113Bk, exposure means 115Y, 115M, 115C, and 115Bk, developing means 117Y, 117M, 117C, and 117Bk, primary transfer rollers (primary transfer means) 133Y, 133M, 133C, and 133Bk, and cleaning means 119Y, 119M, 119C, and 119Bk, which are arranged sequentially in the direction of rotation of the organic photoreceptor in the outer circumferential surface area of ​​the organic photoreceptor.

[0316] Yellow (Y), magenta (M), cyan (C), and black (Bk) toner images are formed on the organic photoreceptors 111Y, 111M, 111C, and 111Bk, respectively.

[0317] The following describes each component of the image forming apparatus other than the organic photoreceptor, taking the image forming unit 110Y as an example when using the drawings.

[0318] 4.1 Charging means The charging means is a means for uniformly charging the surface of the photoreceptor.

[0319] In the present invention, the charging means is preferably a contact or non-contact roller charging type. By using a roller charging means, the amount of ozone generated can be significantly reduced, and the applied voltage can be reduced compared to a corona charging type, thereby reducing power consumption and enabling space saving.

[0320] 3 and 4 is a contact-type roller charging system. The charging unit 113Y in this example is composed of a charging roller arranged in contact with the surface of the organic photoreceptor 111Y and a power source that applies a voltage to the charging roller.

[0321] An example of a contact-type roller charging means will be described. Charging roller 11 shown in Fig. 5 has a configuration in which elastic layer 11b, which is laminated on the surface of core metal 11a, reduces charging noise and provides elasticity to ensure uniform adhesion to organic photoreceptor 111Y, and resistance control layer 11c, which is laminated on the surface of elastic layer 11b as needed to ensure high uniform electrical resistance for charging roller 11 as a whole, and surface layer 11d is laminated on resistance control layer 11c, which is urged toward organic photoreceptor 111Y by compression spring 11e and pressed against the surface of organic photoreceptor 111Y with a predetermined pressure to form a charging nip portion, and is rotated in response to the rotation of organic photoreceptor 111Y.

[0322] The core metal 11a is made of a metal such as iron, copper, stainless steel, aluminum, or nickel, or the surface of such a metal is plated to provide rust resistance and scratch resistance without impairing conductivity, and its outer diameter is, for example, within the range of 3 to 20 mm.

[0323] The elastic layer 11b is made of an elastic material such as rubber to which conductive particles such as carbon black, carbon graphite, alkali metal salts, ammonium salts, etc. are added.

[0324] Specific examples of elastic materials include synthetic rubbers such as natural rubber, ethylene propylene diene methylene rubber (EPDM), styrene-butadiene rubber (SBR), silicone rubber, urethane rubber, epichlorohydrin rubber, isoprene rubber (IR), butadiene rubber (BR), nitrile-butadiene rubber (NBR), and chloroprene rubber (CR), as well as resins such as polyamide resin, polyurethane resin, silicone resin, and fluororesin, and foams such as foam sponge. The degree of elasticity can be adjusted by adding process oil, plasticizer, etc. to the elastic material.

[0325] The volume resistivity of the elastic layer 11b is 1×10 1 ~1×10 10 The volume resistivity of the elastic layer 11b is preferably in the range of Ω·cm. The volume resistivity is a value measured in accordance with JIS K 6911.

[0326] The thickness of the elastic layer 11b is preferably within a range of 500 to 5000 μm, and more preferably within a range of 500 to 3000 μm.

[0327] The resistance control layer 11c is provided for the purpose of providing uniform electrical resistance throughout the charging roller 11, but it is not necessary. The resistance control layer 11c can be provided by coating a material with appropriate electrical conductivity or by covering the layer with a tube with appropriate electrical conductivity.

[0328] Specific materials constituting the resistance control layer 11c include resins such as polyamide resin, polyurethane resin, fluororesin, and silicone resin; and rubbers such as epichlorohydrin rubber, urethane rubber, chloroprene rubber, and acrylonitrile rubber, to which conductive agents such as conductive fine particles made of carbon black, carbon graphite, and the like; conductive metal oxide fine particles made of conductive titanium oxide, conductive zinc oxide, conductive tin oxide, and the like; and conductive fine particles made of alkali metal salts, ammonium salts, and the like have been added.

[0329] The volume resistivity of the resistance control layer 11c is 1×10 -2 ~1×10 14 It is preferably in the range of Ω·cm, and more preferably 1×10 1 ~1×10 10 The volume resistivity of the resistance control layer 11c is in the range of Ω·cm. The volume resistivity is a value measured in accordance with JIS K 6911.

[0330] The thickness of the resistance control layer 11c is preferably in the range of 0.5 to 100 μm, more preferably in the range of 1 to 50 μm, and even more preferably in the range of 1 to 20 μm.

[0331] The surface layer 11d is provided for the purposes of preventing the plasticizer in the elastic layer 11b from bleeding out onto the surface of the resulting charging roller, for the purpose of making the surface of the charging roller slippery and smooth, and for the purpose of preventing leakage even if there is a defect such as a pinhole on the organic photoreceptor 111Y, and is provided by coating the surface with a material having appropriate conductivity or by covering it with a tube having appropriate conductivity.

[0332] When the surface layer 11d is provided by coating a material, specific examples of the material include a base material such as a resin such as polyamide resin, polyurethane resin, acrylic resin, fluororesin, or silicone resin, or epichlorohydrin rubber, urethane rubber, chloroprene rubber, or acrylonitrile rubber to which a conductive agent such as conductive fine particles made of carbon black, carbon graphite, or conductive metal oxide fine particles made of conductive titanium oxide, conductive zinc oxide, or conductive tin oxide has been added. Examples of the coating method include a dip coating method, a roll coating method, and a spray coating method.

[0333] Furthermore, when the surface layer 11d is provided by covering with a tube, specific examples of the tube include nylon 12, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA), polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP), thermoplastic elastomers such as polystyrene, polyolefin, polyvinyl chloride, polyurethane, polyester, and polyamide, to which the above-mentioned conductive agent has been added, and molded into a tube shape. This tube may be heat-shrinkable or non-heat-shrinkable.

[0334] The volume resistivity of the surface layer 11d is 1×10 1 ~1×10 8 It is preferably in the range of Ω·cm, and more preferably 1×10 1 ~1×10 5 The volume resistivity of the surface layer 11d is a value measured in accordance with JIS K 6911.

[0335] The thickness of the surface layer 11d is preferably within a range of 0.5 to 100 μm, more preferably within a range of 1 to 50 μm, and even more preferably within a range of 1 to 20 μm.

[0336] The surface roughness of the surface layer 11d is preferably in the range of 1 to 30 μm, more preferably in the range of 2 to 20 μm, and even more preferably in the range of 5 to 10 μm.

[0337] In the charging roller 11 as described above, a charging bias voltage is applied to the core metal 11a of the charging roller 11 from the power source S1, whereby the surface of the organic photoreceptor 111Y is charged to a predetermined potential of a predetermined polarity.

[0338] Here, the charging bias voltage may be, for example, only a DC voltage, but it is preferable to use an oscillating voltage in which an AC voltage is superimposed on a DC voltage, as this provides excellent charging uniformity.

[0339] 4.2 Exposure means The exposure unit is a unit that exposes the photosensitive member, to which a uniform potential has been applied by the charging unit, based on an image signal, to form an electrostatic latent image corresponding to the image.

[0340] Examples of the exposure means include a means consisting of an LED in which light emitting elements are arranged in an array in the axial direction of the photosensitive member and an imaging element, and a laser optical system.

[0341] 4.3 Developing Method The developing unit supplies toner to the surface of the photosensitive member, and develops the electrostatic latent image formed on the surface of the photosensitive member to form a toner image.

[0342] Specifically, the developing means 117Y shown in FIG. 3 is composed of a developing roller 118Y that has a built-in magnet and rotates while holding a developer, and a voltage application device (not shown) that applies a DC and / or AC bias voltage between the organic photoreceptor 111Y and the developing roller 118Y.

[0343] The rotation of the developing roller 118Y transports toner to the organic photoreceptor 111Y. Then, the thin layer of toner on the developing roller 118Y comes into contact with the organic photoreceptor 111Y and develops the electrostatic latent image on the organic photoreceptor 111Y.

[0344] The developing roller 118Y is connected to a voltage application device. This voltage application device applies a DC and / or AC bias voltage to the developing roller 118Y. By controlling the voltage applied to the developing roller 118Y, the developing bias can be adjusted to a desired value.

[0345] The potential difference (development potential difference) between the potential of the electrostatic latent image carried by developing roller 118Y and organic photoreceptor 111Y forms an electric field at a development section where developing roller 118Y and organic photoreceptor 111Y face each other.

[0346] The toner in the developer transported to the developing unit by the rotation of the developing roller 118Y moves due to the force of the electric field and is attracted to the electrostatic latent image on the organic photoreceptor 111Y. When the electrostatic latent image carried on the organic photoreceptor 111Y is visualized, a toner image corresponding to the shape of the electrostatic latent image is formed on the surface of the organic photoreceptor 111Y.

[0347] <4.4 Transfer Method> The transfer means is a means for transferring the toner image on the organic photoreceptor to a transfer body (intermediate transfer body or transfer material). When an intermediate transfer body is used, the primary transfer roller serves as the transfer means. In the present invention, the "transfer means" is a means for transferring the "toner image on the photoreceptor," and therefore does not include the secondary transfer roller used when transferring from the intermediate transfer body to the transfer material.

[0348] 3 transfers the toner image formed on the organic photosensitive member 111Y to the endless belt-like intermediate transfer member 131. The primary transfer roller 133Y is disposed in contact with the intermediate transfer member 131.

[0349] In the image forming apparatus 100 shown in Figure 3, an intermediate transfer method is adopted in which toner images formed on organic photosensitive bodies 111Y, 111M, 111C, and 111Bk are transferred to an intermediate transfer body 131 by primary transfer rollers (primary transfer means) 133Y, 133M, 133C, and 133Bk, and each toner image transferred to the intermediate transfer body 131 is transferred to a transfer material P by a secondary transfer roller (secondary transfer means) 217, but a direct transfer method may also be adopted in which the toner images formed on the photosensitive bodies are transferred directly to a transfer material P by a transfer means.

[0350] 4.5 Cleaning Methods The cleaning unit 119Y is a unit that removes toner remaining on the surface of the organic photoreceptor 111Y. In this example, the cleaning unit 119Y is configured with a cleaning blade. This cleaning blade is configured with a support member and a blade member supported on the support member via an adhesive layer. The blade member is arranged with its tip facing in the opposite direction (counter direction) to the rotation direction of the organic photoreceptor 111Y at the contact portion with the surface of the organic photoreceptor 111Y.

[0351] The support member is not particularly limited, and any conventionally known member can be used, including, for example, those made of rigid metal, elastic metal, plastic, ceramic, etc. Among these, rigid metal is preferred.

[0352] The blade member may have a multilayer structure, for example, a base layer and an edge layer laminated together. The base layer and the edge layer are preferably made of polyurethane. Examples of polyurethane include those obtained by reacting polyol, polyisocyanate, and, if necessary, a crosslinking agent. [Example]

[0353] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In the following examples, unless otherwise specified, operations were carried out at room temperature (25°C). Furthermore, unless otherwise specified, "%" and "parts" mean "% by mass" and "parts by mass," respectively.

[0354] [Preparation of vinyl resin particle dispersion SA (1)] (First stage polymerization) A 5 L reaction vessel equipped with a stirrer, a temperature sensor, a condenser, and a nitrogen introducing device was charged with 8 parts by mass of sodium dodecyl sulfate and 3,000 parts by mass of ion-exchanged water, and the internal temperature was raised to 80° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. After the temperature was raised, a solution prepared by dissolving 10 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water was added, and the liquid temperature was again raised to 80° C., and a mixed liquid of the following monomers was added dropwise over 1 hour.

[0355] Styrene 480.0 parts by mass n-Butyl acrylate 250.0 parts by mass Methacrylic acid 68.0 parts by mass n-Octyl mercaptan 16.4 parts by mass

[0356] After the dropwise addition, polymerization was carried out by heating and stirring at 80° C. for 2 hours, and vinyl resin particle dispersion A was prepared.

[0357] (Second stage polymerization) A solution of 7 parts by mass of sodium dodecyl sulfate dissolved in 3,000 parts by mass of ion-exchanged water was placed in a 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device, and heated to 98°C. After heating, 300 parts by mass, calculated as solid content, of the vinyl resin particle dispersion A prepared by the first-stage polymerization described above and a mixed liquid prepared by dissolving the following monomers, chain transfer agent, and release agent at 90°C were added thereto.

[0358] Styrene 243.0 parts by mass n-Butyl acrylate 45.5 parts by mass 2-Ethylhexyl acrylate 45.5 parts by mass Methacrylic acid 33.1 parts by mass n-Octyl mercaptan 5.5 parts by mass Behenic acid behenate (mold release agent, melting point 73°C) 130.0 parts by mass

[0359] A dispersion containing emulsified particles (oil droplets) was prepared by mixing and dispersing for one hour using a mechanical disperser with a circulation path, CLEARMIX (manufactured by M-Technique Co., Ltd.) To this dispersion was added a polymerization initiator solution consisting of 6 parts by mass of potassium persulfate dissolved in 200 parts by mass of ion-exchanged water, and the system was heated and stirred at 78°C for one hour to polymerize, preparing vinyl resin particle dispersion B.

[0360] (Third stage polymerization) 400 parts by mass of ion-exchanged water was further added to the amorphous vinyl resin particle dispersion B obtained by the second-stage polymerization and mixed thoroughly, followed by the addition of a solution of 6.0 parts by mass of potassium persulfate dissolved in 400 parts by mass of ion-exchanged water. Further, a mixed solution of the following monomers and chain transfer agent was added dropwise over 1 hour at a temperature of 81°C.

[0361] Styrene 354.8 parts by mass n-Butyl acrylate 143.2 parts by mass Methacrylic acid 52.0 parts by mass n-Octyl mercaptan 8.0 parts by mass

[0362] After the dropwise addition was completed, polymerization was carried out by heating and stirring for 2 hours, and then the mixture was cooled to 28° C. to prepare a vinyl resin particle dispersion SA(1).

[0363] [Preparation of vinyl resin particle dispersion SA (2)] Vinyl resin particle dispersion SA(2) was prepared by carrying out the polymerization reaction and post-reaction treatment in the same manner as in the preparation of the vinyl resin particle dispersion SA(1), except that the monomer mixture used in the first-stage polymerization was changed to the following:

[0364] Styrene 624.0 parts by mass n-Butyl acrylate 120.0 parts by mass Methacrylic acid 56.0 parts by mass n-Octyl mercaptan 16.4 parts by mass

[0365] [Preparation of crystalline polyester resin particle dispersion CP] The following monomers were placed in a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, and heated to 170° C. to dissolve them.

[0366] Tetradecanedioic acid 440 parts by mass 1,6-Hexanediol 173 parts by mass

[0367] Next, 0.8 parts by mass of Ti(OBu)4 was added as an esterification catalyst, the temperature was raised to 235°C, and the reaction was carried out at normal pressure (101.3 kPa) for 5 hours and then under reduced pressure (8 kPa) for 1 hour.

[0368] Then, after cooling to 200° C., the mixture was reacted under reduced pressure (20 kPa) for 1 hour to obtain a crystalline polyester resin 1.

[0369] The resulting crystalline polyester resin 1 had a weight average molecular weight Mw of 20,500, an acid value of 22.1 mgKOH / g, and a melting point Tm of 75.2°C.

[0370] Next, 100 parts by weight of crystalline polyester resin 1 was dissolved in 400 parts by weight of ethyl acetate (Kanto Chemical Co., Ltd.) and mixed with 638 parts by weight of a previously prepared 0.26% by weight sodium lauryl sulfate solution. While stirring, the mixture was subjected to ultrasonic dispersion treatment for 30 minutes at V-LEVEL 300 μA using an ultrasonic homogenizer US-150T (Nippon Seiki Seisakusho Co., Ltd.). The mixture was then heated to 40°C and stirred under reduced pressure for 3 hours using a diaphragm vacuum pump V-700 (BUCHI) to completely remove the ethyl acetate, preparing crystalline polyester resin particle dispersion CP. The crystalline polyester resin particles in the dispersion had a volume-based median diameter of 160 nm.

[0371] [Preparation of Hybrid Amorphous Polyester Resin Particle Dispersion HAP] A mixture of the following vinyl resin monomer, a monomer having a substituent reactive with both the amorphous polyester resin and the vinyl resin, and a polymerization initiator was placed in a dropping funnel.

[0372] Styrene 80.0 parts by mass n-Butyl acrylate 20.0 parts by mass Acrylic acid 10.0 parts by mass Di-t-butyl peroxide (polymerization initiator) 16.0 parts by mass

[0373] Furthermore, the following monomers for the amorphous polyester resin were placed in a four-necked flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, and heated to 170° C. to dissolve them.

[0374] Bisphenol A ethylene oxide 2 mole adduct 59.1 parts by mass Bisphenol A propylene oxide 2 mole adduct 281.7 parts by mass Terephthalic acid 63.9 parts by mass Succinic acid 48.4 parts by mass

[0375] The mixture in the dropping funnel was added dropwise to a four-neck flask over 90 minutes while stirring, and after aging for 60 minutes, unreacted monomer was removed under reduced pressure (8 kPa). 0.4 parts by mass of Ti(OBu)4 was then added as an esterification catalyst, and the mixture was heated to 235°C and reacted under normal pressure (101.3 kPa) for 5 hours and then under reduced pressure (8 kPa) for 1 hour.

[0376] Then, the mixture was cooled to 200° C., and the reaction was carried out under reduced pressure (20 kPa), after which the solvent was removed to obtain a hybrid amorphous polyester resin (A1) modified with a vinyl resin.

[0377] The resulting hybrid amorphous polyester resin (A1) had a weight average molecular weight Mw of 24,000, an acid value of 16.2 mgKOH / g, and a glass transition temperature Tg of 60°C.

[0378] Next, 100 parts by weight of hybrid amorphous polyester resin (A1) was dissolved in 400 parts by weight of ethyl acetate (Kanto Chemical Co., Ltd.) and mixed with 638 parts by weight of a previously prepared 0.26% by weight sodium lauryl sulfate solution. While stirring, the mixture was subjected to ultrasonic dispersion treatment for 30 minutes at V-LEVEL 400 μA using an ultrasonic homogenizer US-150T (Nippon Seiki Seisakusho Co., Ltd.). The mixture was then heated to 40°C and stirred under reduced pressure for 3 hours using a diaphragm vacuum pump V-700 (BUCHI), completely removing the ethyl acetate to prepare a hybrid amorphous polyester resin particle dispersion HAP with a solids content of 13.5% by weight. The hybrid amorphous polyester resin particles in the dispersion had a volume-based median diameter of 98 nm.

[0379] [Preparation of amorphous polyester resin particle dispersion AP] The following monomers for the amorphous polyester resin were placed in a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer and a thermocouple, and heated to 170° C. to dissolve them.

[0380] Bisphenol A ethylene oxide 2 mole adduct 59.1 parts by mass Bisphenol A propylene oxide 2 mole adduct 281.7 parts by mass Terephthalic acid 63.9 parts by mass Succinic acid 48.4 parts by mass

[0381] While stirring, 0.4 parts of Ti(OBu)4 was added as an esterification catalyst. After reacting for 6 hours at 235°C under a nitrogen gas flow, the mixture was cooled to 200°C and reacted for an additional 5 hours under reduced pressure (20 kPa), after which the solvent was removed to obtain amorphous polyester resin (B).

[0382] The resulting amorphous polyester resin (B) had a weight average molecular weight Mw of 27,000, an acid value of 18.0 mgKOH / g, and a glass transition temperature Tg of 60°C.

[0383] 100 parts by weight of amorphous polyester resin (B) was dissolved in 400 parts by weight of ethyl acetate (Kanto Chemical Co., Ltd.) and mixed with 638 parts by weight of a previously prepared 0.26% by weight sodium lauryl sulfate solution. While stirring, the mixture was subjected to ultrasonic dispersion treatment for 30 minutes at V-LEVEL 400 μA using an ultrasonic homogenizer US-150T (Nippon Seiki Seisakusho Co., Ltd.). The mixture was then heated to 40°C and stirred under reduced pressure for 3 hours using a diaphragm vacuum pump V-700 (BUCHI), completely removing the ethyl acetate to prepare an amorphous polyester resin particle dispersion AP with a solids content of 13.5% by weight. The amorphous polyester resin particles in the dispersion had a volume-based median diameter of 99 nm.

[0384] [Preparation of colorant particle dispersion] The following ingredients were mixed and pre-dispersed for 10 minutes using a homogenizer (Ultra Turrax, manufactured by IKA), and then dispersed for 30 minutes at a pressure of 245 MPa using a high-pressure impact disperser, Ultimizer (manufactured by Sugino Machine).

[0385] Carbon black (Cabot Corporation, Regal 330) 100 parts by mass Anionic surfactant (Neogen SC, manufactured by Daiichi Kogyo Seiyaku) 15 parts by mass Ion-exchanged water 400 parts by mass

[0386] Ion-exchanged water was further added to the obtained dispersion to adjust the solid content to 15% by mass, thereby preparing a colorant particle dispersion.

[0387] The volume-based median diameter of the colorant particles in the obtained colorant particle dispersion was measured using a Coulter Multisizer 3 (manufactured by Beckman Coulter, Inc.) and was found to be 110 nm.

[0388] [Preparation of Toner 1] A reaction vessel equipped with a stirrer, temperature sensor, and cooling tube was charged with 441 parts by mass (solids content) of vinyl resin particle dispersion SA1, 45 parts by mass (solids content) of crystalline polyester resin particle dispersion CP, 1% by mass (solids content) of dodecyl diphenyl ether disulfonic acid sodium salt in terms of resin ratio, and 200 parts by mass of ion-exchanged water. At room temperature (25°C), a 5 mol / L aqueous sodium hydroxide solution was added to adjust the pH to 11.

[0389] Next, 40 parts by weight (solids equivalent) of colorant particle dispersion was added, and a solution of 40 parts by weight of magnesium chloride dissolved in 40 parts by weight of ion-exchanged water was added over 15 minutes at 30°C while stirring. After leaving the mixture for 5 minutes, the temperature was raised to 85°C over 90 minutes. After reaching 85°C, the stirring speed was adjusted so that the particle size growth rate was 0.02 μm / min. The particles were allowed to grow until the volume-based median diameter measured using a Coulter Multisizer 3 (Beckman Coulter, Inc.) reached 6.0 μm. When the particle size reached 6.0 μm, the stirring speed was adjusted to stop particle size growth and allow particle fusion to proceed until the average circularity of the toner particles reached 0.945. This yielded toner base particle precursors.

[0390] Next, 54 parts by weight (solids equivalent) of hybrid amorphous polyester resin particle dispersion HAP was added over 90 minutes as a dispersion of resin for the protrusions, and when the supernatant of the reaction solution became transparent, an aqueous solution of 15 parts by weight of sodium chloride dissolved in 60 parts by weight of ion-exchanged water was added to suppress particle size regrowth, and particle fusion was allowed to proceed until the average circularity of the toner particles reached 0.961.Then, the mixture was cooled to 30°C at a cooling rate of 2.5°C / min.

[0391] The toner cake was then subjected to solid-liquid separation, and the dehydrated toner cake was washed by repeating the process of redispersing the toner cake in ion-exchanged water and solid-liquid separation three times. After washing, the toner cake was dried at 35°C for 24 hours to obtain toner base particles having multiple protrusions formed on the surface.

[0392] To 100 parts by weight of the resulting toner base particles, 0.75 parts by weight of hydrophobic silica particles (volume-based median diameter: 12 nm, hydrophobicity: 68) were added as non-lubricant particles, 0.5 parts by weight of hydrophobic alumina particles (volume-based median diameter: 20 nm, hydrophobicity: 63, Mohs hardness: 8.5), and 0.4 parts by weight of sol-gel silica particles (1) (volume-based median diameter: 82 nm). Furthermore, 0.4 parts by weight of zinc stearate particles StZn(1) (volume-based median diameter: 1210 nm) were added as lubricant particles. The mixture was mixed in a Henschel mixer (manufactured by Mitsui Miike Chemical Engineering Co., Ltd.) at a rotor circumferential speed of 40 mm / sec at 32°C for 20 minutes. After mixing, coarse particles were removed using a sieve with 45 μm openings to produce Toner 1. The average spacing D1 of the convex portions of the toner base particles in Toner 1 was 103 nm.

[0393] [Preparation of Toner 2] Toner 2 was produced in the same manner as Toner 1, except that the temperature at the time of adding the hybrid amorphous polyester resin particle dispersion HAP was appropriately changed. The average spacing D1 of the convex portions of the toner base particles in Toner 2 was 198 nm.

[0394] [Preparation of Toner 3] Toner 3 was produced in the same manner as Toner 1, except that the temperature at the time of adding the hybrid amorphous polyester resin particle dispersion HAP was changed appropriately and sol-gel silica particles (2) (volume-based median diameter: 48 nm) were added as non-lubricant particles instead of sol-gel silica particles (1). The average spacing D1 of the convex portions of the toner base particles in Toner 3 was 57 nm.

[0395] [Preparation of Toner 4] Toner 4 was produced in the same manner as Toner 1, except that the temperature at the time of adding the hybrid amorphous polyester resin particle dispersion HAP was appropriately changed, and sol-gel silica particles (3) (volume-based median diameter: 15 nm) were added as non-lubricant particles instead of sol-gel silica particles (1). The average spacing D1 of the convex portions of the toner base particles in Toner 4 was 20 nm.

[0396] [Preparation of Toner 5] Toner 5 was prepared in the same manner as Toner 1, except that zinc stearate particles StZn(2) (volume-based median diameter: 5370 nm) were added as lubricant particles instead of zinc stearate particles StZn(1).

[0397] [Preparation of Toner 6] Toner 6 was prepared in the same manner as Toner 1, except that zinc stearate StZn(3) (volume-based median diameter: 369 nm) was added as the lubricant particles instead of zinc stearate StZn(1).

[0398] [Preparation of Toner 7] Toner 7 was prepared in the same manner as Toner 1, except that hydrophobic titania particles (volume-based median diameter: 20 nm, hydrophobicity: 61, Mohs hardness: 6.5) were added as non-lubricant particles instead of hydrophobic alumina particles.

[0399] [Preparation of Toner 8] Toner 8 was produced in the same manner as Toner 1, except that amorphous polyester resin particle dispersion AP was used instead of hybrid amorphous polyester resin particle dispersion HAP as the dispersion of the resin for the convex portions of the toner base particles. The average spacing D1 of the convex portions of the toner base particles in Toner 8 was 146 nm.

[0400] [Preparation of Toner 9] Toner 9 was produced in the same manner as Toner 1, except that vinyl resin particle dispersion SA(2) was used instead of hybrid amorphous polyester resin particle dispersion HAP as the dispersion of the resin for the convex portions of the toner base particles. The average spacing D1 of the convex portions of the toner base particles in Toner 9 was 292 nm.

[0401] [Preparation of Toner 10] Toner 10 was prepared in the same manner as Toner 1, except that aluminum stearate particles StAl (volume-based median diameter: 1580 nm) were added as lubricant particles instead of zinc stearate particles StZn(1).

[0402] [Preparation of Toner 11] Toner 11 was prepared in the same manner as Toner 1, except that calcium fluoride particles CaF2(1) (volume-based median diameter: 210 nm) were added as lubricant particles instead of zinc stearate particles StZn(1).

[0403] [Preparation of Toner 12] Toner 12 was produced in the same manner as Toner 1, except that the hybrid amorphous polyester resin particle dispersion HAP was not added as the dispersion of the resin for the convex portions of the toner base particles, and convex portions were not formed.

[0404] [Preparation of Toner 13] Toner 2 was produced in the same manner as Toner 1, except that the temperature at the time of adding the hybrid amorphous polyester resin particle dispersion HAP was appropriately changed. The average spacing D1 of the convex portions of the toner base particles in Toner 2 was 57 nm.

[0405] [Preparation of Toner 14] Toner 14 was prepared in the same manner as Toner 2, except that calcium fluoride particles CaF2(2) (volume-based median diameter: 105 nm) were added as lubricant particles instead of zinc stearate particles StZn(1).

[0406] [Ratio R of fatty acid metal salt particles liberated from toner base particles for each toner] The liberation rate R of fatty acid metal salt particles from the toner base particles for each toner was determined by ultrasonic treatment under the following conditions.

[0407] [Conditions for ultrasonic treatment] Step 1: The net intensity W1 of the metal elements originating from the fatty acid metal salt particles in the toner particles is measured by X-ray fluorescence analysis. Step 2: Prepare an aqueous dispersion of toner particles. Step 3: The prepared aqueous dispersion is subjected to ultrasonic treatment. Step 4: The fatty acid metal salt particles liberated from the toner base particles by ultrasonic treatment are removed. Step 5: In the toner particles from which the liberated fatty acid metal salt particles have been removed, the net intensity W2 of the metal elements derived from the fatty acid metal salt particles is measured by fluorescent X-ray analysis. Step 6: Calculate the liberation rate R [%] using the following formula (2). Formula (2) R=(W1-W2) / W1×100

[0408] In steps 1 and 5, the NET intensities W1 and W2 of the metal elements derived from the fatty acid metal salt particles were measured using an X-ray fluorescence analyzer "XRF-1700" (manufactured by Shimadzu Corporation). Specifically, the NET intensity was measured by pelletizing 2 g of toner particles under a load of 15 t for 10 seconds, and measuring the pellets using qualitative and quantitative analysis under the following conditions. The Kα peak angle of the element to be measured (metal element derived from the fatty acid metal salt particles) was determined from a 2θ table and used for the measurement.

[0409] -Measurement conditions- Slit: Standard Attenuator: None Spectroscopic crystal (Ti=LiF, Si=PET) Detector (Ti=SC, Si=FPC)

[0410] In step 2, the aqueous dispersion of toner particles was prepared by wetting 3 g of toner particles with 40 g of a 0.2% by mass aqueous solution of polyoxyethyl phenyl ether in a 100 mL plastic cup.

[0411] The ultrasonic treatment in step 3 was carried out using an ultrasonic homogenizer "US-1200" (manufactured by Nippon Kikai Co., Ltd.), with ultrasonic energy adjusted so that the value of the ammeter showing the vibration indicator value attached to the main device indicated 60 μA (50 W), and by applying it to the aqueous dispersion prepared in step 2 for 2 minutes.

[0412] In step 4, the fatty acid metal salt particles liberated from the toner base particles were removed by filtering using a filter with 1 μm openings and washing with 60 mL of pure water. Furthermore, the toner particles were dried in preparation for the measurement in step 5.

[0413] The liberation ratio R of fatty acid metal salt particles from the toner base particles for each toner, determined by the above method, is shown in the table below.

[0414] [Table 1]

[0415] [Preparation of developer] (Preparation of Carrier Core Particles) The raw materials were weighed to give a mixture of 35 mol% MnO, 14.5 mol% MgO, 50 mol% Fe2O3, and 0.5 mol% SrO, mixed with water, and then pulverized in a wet media mill for 5 hours to obtain a slurry.

[0416] The resulting slurry was dried using a spray dryer to obtain spherical particles. After adjusting the particle size, the particles were heated at 950°C for 2 hours and pre-fired. The particles were then pulverized in a wet ball mill using 0.3 cm diameter stainless steel beads for 1 hour, and then further pulverized using 0.5 cm diameter zirconia beads for 4 hours. PVA was added as a binder at 0.8% by mass relative to the solid content, and the mixture was then granulated and dried using a spray dryer. The mixture was then sintered in an electric furnace at 1350°C for 5 hours.

[0417] The mixture was then crushed and further classified to adjust the particle size, and then magnetic separation was performed to separate out low magnetic particles to obtain carrier core particles with a particle size of 35 μm.

[0418] (Creating coating material) Cyclohexyl methacrylate and methyl methacrylate were added to a 0.3% by mass aqueous solution of sodium benzenesulfonate at a mass ratio of 5:5 (copolymerization ratio), and potassium persulfate was added in an amount equivalent to 0.5% by mass of the total amount of monomers. The emulsion polymerization was carried out and the resulting coating material was dried by spray drying. The weight-average molecular weight of the resulting coating material was 500,000.

[0419] (Creating the carrier) 100 parts by mass of the "carrier core particles" prepared above as core particles and 4.5 parts by mass of the "coating material" were added to a high-speed stirring mixer equipped with horizontal stirring blades, and the mixture was mixed and stirred for 15 minutes at 22°C under conditions where the peripheral speed of the horizontal rotor was 8 m / sec, and then mixed for 50 minutes at 120°C to coat the surfaces of the core particles with the coating material through the action of mechanical impact force (mechanochemical method), thereby producing the "carrier."

[0420] (Toner and carrier mixture) The toner and carrier thus prepared were mixed for 30 minutes so that the toner concentration was 6.5% by mass, and a developer containing each toner was prepared using a V-type mixer.

[0421] [Preparation of organic photoreceptor 1] (Preparation of conductive support) The surface of a cylindrical aluminum support was machined to prepare a conductive support.

[0422] (Formation of intermediate layer) The following components were mixed in the amounts shown below, and dispersed batchwise for 10 hours using a sand mill as a disperser to prepare a coating solution for forming an intermediate layer. The coating solution was applied to the surface of a conductive support by dip coating and dried at 110°C for 20 minutes to form a 2 μm thick intermediate layer on the conductive support. X1010 (manufactured by Daicel-Evonik) was used as the polyamide resin, and SMT-500SAS (manufactured by Teika Corporation, number average primary particle diameter: 0.035 μm) was used as the titanium oxide particles.

[0423] Polyamide resin 10 parts by mass Titanium oxide particles 11 parts by mass Ethanol 200 parts by mass

[0424] (Formation of Charge Generation Layer) The following components were mixed in the amounts indicated and dispersed using a circulating ultrasonic homogenizer (RUS-600TCVP, manufactured by Nippon Seiki Seisakusho Co., Ltd.) at 19.5 kHz and 600 W with a circulation flow rate of 40 L / h for 0.5 hours to prepare a coating solution for forming a charge generating layer. The resulting coating solution was applied to the surface of the intermediate layer by dip coating and air-dried to form a 0.3 μm-thick charge generating layer on the intermediate layer. The charge generating materials used were titanyl phthalocyanine, which exhibits clear peaks at 8.3°, 24.7°, 25.1°, and 26.5° in Cu-Kα characteristic X-ray diffraction spectroscopy, and a mixed crystal of a 1:1 adduct of (2R,3R)-2,3-butanediol and unadducted titanyl phthalocyanine. S-LEC® BL-1 (manufactured by Sekisui Chemical Co., Ltd.) was used as the polyvinyl butyral resin. The mixed solvent used was 3-methyl-2-butanone / cyclohexanone = 4 / 1 (volume ratio).

[0425] Charge generating material 24 parts by mass Polyvinyl butyral resin 12 parts by mass Mixed solvent 400 parts by mass

[0426] (Formation of charge transport layer) A coating solution for the charge transport layer, containing the following components in the following amounts, was applied to the surface of the charge generation layer by dip coating and dried at 120°C for 70 minutes to form a 24 μm-thick charge transport layer on the charge generation layer. The polycarbonate resin used was Iupilon® Z300 (Mitsubishi Gas Chemical Company, Inc., bisphenol Z-type polycarbonate). The antioxidant used was IRGANOX® 1010 (BASF Japan).

[0427] 60 parts by weight of a charge transport material represented by the following CTM-(1) Polycarbonate resin 100 parts by mass THF (tetrahydrofuran) 800 parts by mass Toluene 200 parts by mass Antioxidant 4 parts by mass

[0428] [ka]

[0429] (Formation of protective layer) A coating solution for forming a protective layer, prepared by mixing the following components in the following amounts, was applied to the surface of the charge transport layer using a circular slide hopper coater. The resulting coating solution film was irradiated with ultraviolet light (dominant wavelength: 365 nm) using a metal halide lamp for 1 minute (ultraviolet irradiance: 16 mW / cm). 2 , Accumulated light intensity: 960mJ / cm 2 The film was cured to form a protective layer having a thickness of 3.0 μm on the charge transport layer. The polymerization initiator used was IRGACURE (registered trademark) 819 (manufactured by BASF Japan Ltd.).

[0430] 120 parts by mass of polymerizable monomer represented by the above chemical formula M2 Tin oxide particles 100 parts by mass Polymerization initiator 10 parts by mass 2-butanol 400 parts by mass THF (tetrahydrofuran) 100 parts by mass 30 parts by weight of the charge transport material represented by CTM-(1) above

[0431] In this way, organic photoreceptor 1 was produced.

[0432] [Preparation of organic photoreceptor 2] Organic photoreceptor 2 was prepared in the same manner as organic photoreceptor 1, except that the metal oxide particles mixed in the protective layer-forming coating liquid were changed from tin oxide particles to silicon oxide particles.

[0433] [Preparation of Organic Photoreceptor 3] Organic photoreceptor 3 was prepared in the same manner as organic photoreceptor 1, except that tin oxide particles were not mixed into the coating liquid for forming the protective layer.

[0434] [Preparation of Organic Photoreceptor 4] Organic photoreceptor 4 was prepared in the same manner as organic photoreceptor 1, except that no polymerization initiator was mixed into the coating liquid for forming the protective layer, and the film of the coating liquid for forming the protective layer was cured by irradiating it with electron beams instead of ultraviolet rays.

[0435] [Preparation of Organic Photoreceptor 5] Organic photoreceptor 5 was prepared in the same manner as organic photoreceptor 1, except that the protective layer was prepared as follows.

[0436] (Preparation of Protective Layer in Organic Photoreceptor 5) A protective layer-forming coating solution containing the following components in the following amounts was applied to the surface of the charge transport layer using a circular slide hopper coater and dried at 120°C for 70 minutes to form a 3.0 μm-thick protective layer on the charge transport layer. The polycarbonate resin used was Iupilon® Z300 (Mitsubishi Gas Chemical Company, Inc., bisphenol Z-type polycarbonate). The antioxidant used was IRGANOX® 1010 (BASF Japan).

[0437] 60 parts by weight of the charge transport material represented by CTM-(1) above Polycarbonate resin 100 parts by mass THF (tetrahydrofuran) 1600 parts by mass Toluene 400 parts by mass Antioxidant 4 parts by mass

[0438] [Image formation system] A commercially available full-color multifunction printer, "bizhub C650i" (manufactured by Konica Minolta), which employs a contact roller charging method, was used, and the organic photoreceptor and developer prepared above were installed in the cyan position in the combinations shown in the table below to form each image forming system. In Table II, "the present invention" in the remarks column for image forming systems Nos. 8, 9, and 11 should be read as "reference example." The evaluation of each image forming system will be described below.

[0439] [Evaluation of wear amount α value] A durability test was conducted at room temperature and humidity (20°C, 50% RH) using a 5% print chart, printing 300,000 sheets of A4-size neutral paper. The thickness of the protective layer of the organic photoreceptor was measured before and after the durability test, and the amount of wear was calculated and evaluated. The thickness of the protective layer was measured at 10 random locations in a uniform thickness area (excluding areas with thickness variations at the leading and trailing edges of the coating) using a film thickness gauge, and the average of these measurements was used as the protective layer thickness. The film thickness gauge used was an eddy current film thickness gauge "EDDY560C" (manufactured by HELMUT FISCHER GMBTE CO.). The difference in protective layer thickness before and after the durability test was used as the amount of wear. The amount of wear (μm) per 100 krots (100,000 rotations) was defined as the α value and reported. The measurement results are shown in the table below. An α value of 1.2 or less was considered acceptable for practical use, and an α value of 0.7 or less was considered even better.

[0440] [Evaluation of deposits on organic photoreceptors] A durability test was conducted in a normal temperature and humidity environment (20°C, 50% RH) by printing 5,000 sheets of A4-size neutral paper using a 5% print chart. After the durability test, the surface of the organic photoreceptor was observed under a microscope, and the total number of developer-derived deposits was measured in three 20mm x 40mm fields: the back, center, and front. The measurement results are shown in the table below. A total number of deposits of 10 or less was considered acceptable in terms of quality.

[0441] [Image evaluation] In an environment of 10°C and 15% RH, 20,000 sheets of A3-size neutral paper were printed with an 80% coverage image, with a halftone area at the front and a white area at the back in the paper transport direction. The white area of ​​the 20,000th sheet was visually observed, and staining due to toner slip-through was evaluated based on the following criteria. The evaluation results are shown in the table below. Evaluation results of "◎" and "○" were judged to be acceptable.

[0442] ⊚: No staining occurred on the white background. ◯: Slight streak-like stains occurred on the white background, but this does not pose a problem in practical use. ×: Clear streak-like stains were observed on the white background, and there was a problem in practical use.

[0443] [Table 2]

[0444] From the results of the examples, it is clear that the image forming system of the present invention makes it possible to simultaneously suppress wear of the organic photoreceptor and reduce deposits on the organic photoreceptor. [Explanation of symbols]

[0445] 1. Toner base particle precursor 2 Convex part 11 Charging roller 11a Core metal 11b Elastic layer 11c Resistance control layer 11d surface layer 11e Compression spring 100 Image forming device 110Y, 110M, 110C, 110Bk Image forming unit 111Y, 111M, 111C, 111Bk photoconductor 113Y, 113M, 113C, 113Bk Charging means (charging roller) 115Y, 115M, 115C, 115Bk Exposure means 117Y, 117M, 117C, 117Bk developing means 118Y, 118M, 118C, 118Bk developing roller 119Y, 119M, 119C, 119Bk Cleaning means 133Y, 133M, 133C, 133Bk Transfer means (primary transfer roller)

Claims

1. An image forming system using an organic photoreceptor and a toner for developing an electrostatic image containing toner particles, the organic photoreceptor has a protective layer containing a cured resin, the toner particles have a shape in which at least one type of lubricant particle and at least one type of non-lubricant particle are contained or adhered to the surfaces of the plurality of convex portions or to the surfaces between the plurality of convex portions of the toner base particle, an average interval D1 between the convex portions on the surface of the toner base particle, a median diameter D2 of the lubricant particles having the smallest median diameter, and a median diameter D3 of the non-lubricant particles having the largest median diameter satisfy the relationship of the following formula (1), the convex portions contain a hybrid amorphous polyester resin in which a vinyl-based polymerization segment and an amorphous polyester-based polymerization segment are bonded via a bireactive monomer, the lubricant particles are fatty acid metal salt particles, The non-lubricant particles are inorganic particles or organic particles. An image forming system comprising: Formula (1) D3≦D1≦D2

2. At least one of the non-lubricant particles has a Mohs hardness of 8 or more.

2. The image forming system according to claim 1.

3. The protective layer contains metal oxide particles.

2. The image forming system according to claim 1.

4. Equipped with a roller charging system 2. The image forming system according to claim 1.

5. In the toner particles, the liberation rate R of the fatty acid metal salt particles from the toner base particles, as determined by an ultrasonic treatment method under the following conditions, is in the range of 20 to 60%:

2. The image forming system according to claim 1. [Conditions for ultrasonic treatment] Step 1: The NET strength W1 of the metal elements originating from the fatty acid metal salt particles in the toner particles is measured by fluorescent X-ray analysis. Step 2: Prepare an aqueous dispersion of toner particles. Step 3: The prepared aqueous dispersion is subjected to ultrasonic treatment. Step 4: The fatty acid metal salt particles liberated from the toner base particles by ultrasonic treatment are removed. Step 5: In the toner particles from which the liberated fatty acid metal salt particles have been removed, the NET strength W2 of the metal elements derived from the fatty acid metal salt particles is measured by fluorescent X-ray analysis. Step 6: The liberation rate R [%] is calculated using the following formula (2). Formula (2) R=(W1-W2) / W1×100

6. An image forming method using an organic photoreceptor and a toner for developing an electrostatic image containing toner particles, comprising: the organic photoreceptor has a protective layer containing a cured resin, the toner particles have a shape in which at least one type of lubricant particle and at least one type of non-lubricant particle are contained or adhered to the surfaces of the plurality of convex portions or to the surfaces between the plurality of convex portions of the toner base particle, an average interval D1 between the convex portions on the surface of the toner base particle, a median diameter D2 of the lubricant particles having the smallest median diameter, and a median diameter D3 of the non-lubricant particles having the largest median diameter satisfy the relationship of the following formula (1), the convex portions contain a hybrid amorphous polyester resin in which a vinyl-based polymerization segment and an amorphous polyester-based polymerization segment are bonded via a bireactive monomer, the lubricant particles are fatty acid metal salt particles, The non-lubricant particles are inorganic particles or organic particles. An image forming method comprising: Formula (1) D3≦D1≦D2

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