Electrophotographic Imaging System

Abstract

To provide an electrophotographic image forming system that achieves both an improvement in wear resistance and prevention of an image memory in long-term use of an electrophotographic photoreceptor.SOLUTION: In an electrophotographic image forming system of the present invention, a toner particle contains a toner base particle, and lubricant as an external additive. The volume-based particle size distribution of the lubricant has two peaks on a small particle diameter side and a large particle diameter side. A volume-based average particle size of the lubricant having the peak on the small particle diameter side is 3.0 μm or less, and a volume-based average particle size of the lubricant having the peak on the large particle diameter side is larger than a volume-based average particle size of the toner base particles. Cleaning means has a brush roller having a plurality of pile bundles, and a cleaning blade. When a pile bundle fineness [dtex] and a pile density [KF / inch2] of the brush roller are defined as X and Y, respectively, the following formulas (1) and (2) are satisfied. Formula (1): 100≤Y≤250; formula (2): 0.7≤X / Y≤2.2.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to electrophotographic imaging systems. More particularly, the present invention relates to an electrophotographic image forming system that achieves both improved wear resistance and suppression of image memory in long-term use of an electrophotographic photosensitive member. [Background technology]

[0002] Conventionally, in electrophotographic image forming systems, a lubricant has been supplied to the surface of an electrophotographic photosensitive member (hereinafter also simply referred to as "photosensitive member") to reduce the frictional force between the surface of the photosensitive member and a cleaning blade, thereby preventing the toner for developing electrostatic images (hereinafter also simply referred to as "toner") from slipping through and preventing wear of the photosensitive member.

[0003] Lubricant can be applied to the photoreceptor surface using a brush or by incorporating it into the toner. The latter method is widely used in electrophotographic image forming systems due to its compact size and ease of application. However, this method can pose a problem of image memory due to differences in image print coverage. "Image memory" refers to an image defect in which, when printing one image chart (the first image chart) followed by another (the second image chart), uneven image density appears in the output image of the second image chart, corresponding to the printed and unprinted areas of the first image chart. Large differences in image print coverage result in uneven distribution of lubricant on the photoreceptor, which in turn causes unevenness in the photoreceptor surface potential. This unevenness in the photoreceptor surface potential is the cause of image memory.

[0004] Patent Document 1 discloses a technique for using a lubricant having a peak on the small particle size side and a lubricant having a peak on the large particle size side in combination to prevent uneven distribution of the lubricant when the lubricant is contained in the toner and supplied. In this technique, the lubricant having a peak on the small particle size side is less likely to separate from the toner base particles and is therefore more likely to be supplied to the toner application area on the photoreceptor (the area on the photoreceptor corresponding to the printed area of ​​the image chart), while the lubricant having a peak on the large particle size side is more likely to separate from the toner base particles and is therefore more likely to be supplied to the toner non-application area on the photoreceptor (the area on the photoreceptor corresponding to the non-printed area of ​​the image chart).

[0005] Due to this mechanism of action, the technology of using a lubricant with a peak on the small particle size side and a lubricant with a peak on the large particle size side in combination can prevent uneven distribution of the lubricant on the photoreceptor to some extent. However, in order to more stably form high-quality images, there has been a demand for the development of an electrophotographic image forming system that can further suppress image memory. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-228763 Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made in consideration of the above problems and circumstances, and the problem to be solved is to provide an electrophotographic image forming system which achieves both improved wear resistance and suppression of image memory in long-term use of an electrophotographic photosensitive member. [Means for solving the problem]

[0008] In order to solve the above problems, the present inventors have investigated the causes of the above problems and have found that by using, as external additives to toner particles, a lubricant having a peak on the small particle size side (hereinafter also referred to as "small particle size lubricant") and a lubricant having a peak on the large particle size side (hereinafter also referred to as "large particle size lubricant") in combination, and further adjusting the pile bundle fineness and pile density of the brush roller so as to satisfy a specific formula, it is possible to provide an electrophotographic image forming system which achieves both improved wear resistance and suppression of image memory in long-term use of an electrophotographic photosensitive member, and have arrived at the present invention. That is, the above-mentioned problems of the present invention are solved by the following means.

[0009] 1. An electrophotographic image forming system for forming an image using a toner for developing an electrostatic charge image containing toner particles, The electrophotographic image forming apparatus comprises an electrophotographic photosensitive member, a charging means, an exposure means, a developing means, a transfer means, and a cleaning means, the toner particles contain toner base particles and a lubricant as an external additive, the volume-based particle size distribution of the lubricant has two peaks on the small particle side and the large particle side, the volume-based average particle size of the lubricant having the peak on the small particle side is 3.0 μm or less, and the volume-based average particle size of the lubricant having the peak on the large particle side is larger than the volume-based average particle size of the toner base particles, the cleaning means comprises a brush roller having a plurality of pile bundles, and a cleaning blade provided downstream of the brush roller in the rotation direction of the electrophotographic photosensitive member, The pile bundle fineness [dtex] of the brush roller is X, and the pile density [KF / inch 2 ] is Y, the following formulas (1) and (2) are satisfied. death, The Young's modulus of the pile constituting the pile bundle is within the range of 25 to 70 cN / dtex. Electrophotographic image forming system. Formula (1): 100≦Y≦250 Formula (2): 0.7≦X / Y≦2.2

[0010] 2. The electrophotographic photoreceptor has a surface protective layer containing a cured resin. 2. The electrophotographic imaging system of claim 1.

[0011] 3. The lubricant is a particle whose main component is zinc stearate. 3. The electrophotographic image forming system according to claim 1 or 2. [Effects of the Invention]

[0013] According to the above-described means of the present invention, it is possible to provide an electrophotographic image forming system which achieves both improvement in the wear resistance of an electrophotographic photosensitive member in long-term use and suppression of image memory.

[0014] The mechanism by which the effects of the present invention are manifested or the mechanism of action is not clear, but is speculated as follows.

[0015] The electrophotographic image forming system of the present invention is characterized in that the toner particles contain a small particle size lubricant and a large particle size lubricant as external additives. By containing the lubricant as an external additive in the toner particles, the lubricant is supplied onto the photoreceptor, improving the wear resistance of the photoreceptor.

[0016] Furthermore, the small-particle-size lubricant has a large contact area with the toner base particles, which means that it adheres strongly to the toner base particles and is less likely to separate from them. Therefore, the small-particle-size lubricant is more likely to be supplied to the toner-application area on the photoreceptor where the toner base particles move. On the other hand, the large-particle-size lubricant has a small contact area with the toner base particles, which means that the Coulomb force and non-electrostatic force between the toner base particles and the large-particle-size lubricant is smaller, and the Coulomb force due to the development field is overcome, making it more likely to separate from the toner base particles. Therefore, the large-particle-size lubricant is more likely to be supplied to the non-toner-application area on the photoreceptor. In this way, by using both the small-particle-size lubricant and the large-particle-size lubricant, the lubricant is supplied to both the toner-application area and the non-toner-application area on the photoreceptor. Therefore, even when there is a large difference in print coverage, uneven distribution of the lubricant is less likely to occur, and image memory can be suppressed.

[0017] The electrophotographic image forming system of the present invention is also characterized in that the cleaning means comprises a brush roller having a plurality of pile bundles, which has the functions of recovering excess lubricant on the photoreceptor and diffusing small particle lubricant, which tends to be present in large amounts in toner application areas, to non-toner application areas, and conversely diffusing large particle lubricant, which tends to be present in large amounts in non-toner application areas, to non-toner application areas.

[0018] Furthermore, in the brush roller according to the present invention, the pile bundle fineness [dtex] is X, and the pile density [KF / inch 2 ] is defined as Y, the present invention is characterized in that the following formulas (1) and (2) are satisfied. Formula (1): 100≦Y≦250 Formula (2): 0.7≦X / Y≦2.2

[0019] If the brush roller does not satisfy the above conditions, the lubricant recovery and diffusion effect will not be fully exerted, and the problem of the present invention will not be solved. Specifically, if the pile density Y is less than 100, the rubbing force will be too small, and if the pile density Y is more than 250, the working area per pile bundle will be too small, so the lubricant recovery and diffusion effect will not be exerted. If X / Y is less than 0.7, the working area per pile bundle will be too small, and if X / Y is more than 2.2, the contact probability between the pile and the lubricant will be too small, so the lubricant recovery and diffusion effect will not be exerted.

[0020] By satisfying the above conditions, the brush roller according to the present invention has an appropriate range of movement per pile bundle, abrasive force, and contact probability between the pile and the lubricant, which significantly increases the recovery and diffusion effect of the lubricant and effectively suppresses image memory.

[0021] These mechanisms of expression or action make it possible to simultaneously improve the abrasion resistance of the electrophotographic photosensitive member during long-term use and suppress image memory in the electrophotographic image forming system of the present invention. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram illustrating an example of a particle size distribution of a lubricant having peaks on the small particle size side and the large particle size side. [Figure 2] A diagram for explaining the cumulative frequency and content ratio of the particle size distribution of a lubricant having peaks on the small particle side and the large particle side. [Figure 3] Schematic diagram of cleaning means [Figure 4] Schematic diagram of an image forming apparatus DETAILED DESCRIPTION OF THE INVENTION

[0023] The electrophotographic image forming system of the present invention is an electrophotographic image forming system that forms an image using a toner for developing an electrostatic charge image containing toner particles, and is equipped with an electrophotographic photosensitive member, a charging means, an exposure means, a developing means, a transfer means, and a cleaning means, the toner particles contain toner base particles and a lubricant as an external additive, the volume-based particle size distribution of the lubricant has two peaks, one on a small particle size side and one on a large particle size side, the volume-based average particle size of the lubricant having the peak on the small particle size side is 3.0 μm or less, and the volume-based average particle size of the lubricant having the peak on the large particle size side is larger than the volume-based average particle size of the toner base particles, the cleaning means has a brush roller having a plurality of pile bundles, and a cleaning blade provided on the downstream side of the brush roller in the rotation direction of the electrophotographic photosensitive member, and the pile bundle fineness [dtex] of the brush roller is X, and the pile density [KF / inch 2 ] is defined as Y, the above formulas (1) and (2) are satisfied. This feature is a technical feature common to or corresponding to the following embodiments.

[0024] In an embodiment of the electrophotographic image forming system of the present invention, the electrophotographic photoreceptor preferably has a surface protective layer containing a cured resin, thereby further improving the abrasion resistance of the electrophotographic photoreceptor.

[0025] In an embodiment of the electrophotographic image forming system of the present invention, the lubricant is preferably particles containing zinc stearate as a main component, because particles containing zinc stearate as a main component have a low adhesive force with toner base particles and are easily transferred to the photoreceptor even with a small amount added.

[0026] In an embodiment of the electrophotographic image forming system of the present invention, the Young's modulus of the pile constituting the pile bundle is preferably within the range of 25 to 70 cN / dtex, which makes the abrasion force appropriate and further improves the recovery and diffusion effect of the lubricant.

[0027] 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.

[0028] <1 Overview of Electrophotographic Image Forming System> The electrophotographic image forming system of the present invention (hereinafter also simply referred to as "image forming system") is an electrophotographic image forming system that forms an image using a toner for developing an electrostatic charge image (hereinafter also simply referred to as "toner") containing toner particles, and is equipped with an electrophotographic photosensitive member (hereinafter also simply referred to as "photosensitive member"), a charging unit, an exposure unit, a developing unit, a transfer unit, and a cleaning unit, the toner particles contain toner base particles and an external additive, the external additive is at least a lubricant, the volume-based particle size distribution of the lubricant has two peaks on the small particle size side and the large particle size side, and the small particle size the volume-based average particle diameter of the lubricant having a peak on the larger particle diameter side (hereinafter also referred to as "lubricant on the smaller particle diameter side") is 3.0 μm or less, and the volume-based average particle diameter of the lubricant having a peak on the larger particle diameter side (hereinafter also referred to as "lubricant on the larger particle diameter side") is larger than the volume-based average particle diameter of the toner base particles, the cleaning means has a brush roller having a plurality of pile bundles and a cleaning blade provided on the downstream side of the brush roller in the rotation direction of the electrophotographic photosensitive member, the pile bundle fineness [dtex] of the brush roller is X, and the pile density [KF / inch 2] is defined as Y, the following formulas (1) and (2) are satisfied. Formula (1): 100≦Y≦250 Formula (2): 0.7≦X / Y≦2.2

[0029] In the image forming system of the present invention, the device unit is particularly referred to as an “image forming device.” The image forming system of the present invention forms an image by using the image forming device and the toner particles of the present invention.

[0030] The following describes the configurations of the toner for developing electrostatic images and the image forming apparatus.

[0031] <2. Toner for developing electrostatic images> The toner particles contained in the electrostatic image developing toner according to the present invention contain toner base particles and an external additive, and the external additive is at least a lubricant, and the volume-based particle size distribution of the lubricant has two peaks, one on the small particle side and one on the large particle side, and the volume-based average particle size of the lubricant having the peak on the small particle side (the lubricant on the small particle side) is 3.0 μm or less, and the volume-based average particle size of the lubricant having the peak on the large particle side (the lubricant on the large particle side) is larger than the volume-based average particle size of the toner base particles.

[0032] In the present invention, "toner base particles" refer to particles that constitute the base of "toner particles." "Toner base particles" contain at least a binder resin and a colorant, and may contain other components such as a release agent (wax) and a charge control agent, as necessary. "Toner base particles" are called "toner particles" when external additives are added. "Toner for developing electrostatic images" refers to an aggregate of "toner particles."

[0033] <2.1 Lubricants> The toner particles according to the present invention contain a lubricant as an external additive.

[0034] The lubricant supplied to the photoreceptor is uniformly distributed on the photoreceptor by the brush roller and then spread over the photoreceptor by the cleaning blade. The lubricant spread over the photoreceptor reduces friction between the cleaning blade and the photoreceptor surface, preventing toner from slipping through and wear on the photoreceptor.

[0035] The lubricant according to the present invention is characterized in that its volumetric particle size distribution has two peaks, one on the small particle side and one on the large particle side, and the volumetric average particle size of the lubricant having the peak on the small particle side (the lubricant on the small particle side) is 3.0 μm or less, and the volumetric average particle size of the lubricant having the peak on the large particle side (the lubricant on the large particle side) is larger than the volumetric average particle size of the toner base particles.

[0036] When the volume-based average particle diameter of the lubricant having a peak on the small particle diameter side is 3.0 μm or less, it adheres to the toner base particles and exhibits the function of adhering to the toner application area on the photoreceptor. Furthermore, it is preferable that the volume-based average particle diameter of the lubricant having a peak on the small particle diameter side is in the range of 1.0 to 3.0 μm. By having a volume-based average particle diameter of 1.0 μm or more, the amount of lubricant adhered is not too small, and by having a volume-based average particle diameter of 3.0 μm or less, it is difficult for the lubricant to separate from the toner base particles and it easily adheres to the toner application area.

[0037] The volume-based average particle diameter of the lubricant having a peak on the larger particle size side is larger than the volume-based average particle diameter of the toner base particles. If the volume-based average particle diameter is larger than that of the toner base particles, the lubricant will not adhere to the toner base particles and will function to be developed in the toner non-application area independently of the toner particles. Furthermore, the volume-based average particle diameter of the lubricant having a peak on the larger particle size side is preferably within the range of 8.0 to 15.0 μm. By having a particle diameter of 8.0 μm or more, the lubricant will be more likely to be separated from the toner base particles and adhere to the toner non-application area, and by having a particle diameter of 15.0 μm or less, variation in the amount of adhesion in the axial direction of the photoreceptor will be suppressed.

[0038] The volumetric particle size of the lubricant can be measured, for example, by separating the toner base particles and external additives from the toner using a flow particle image analyzer "FPIA-2100" (manufactured by Sysmex Corporation) according to the following procedure.

[0039] 5 g of toner particles and 50 mL of 0.7% aqueous sodium dodecylbenzenesulfonate solution are placed in a 100 mL beaker and dispersed by stirring at 300 rpm for 5 minutes using a magnetic stirrer "Model MS500D" (manufactured by Yamato Scientific).

[0040] After the dispersion, ultrasonic vibration is applied to the toner dispersion liquid for 10 minutes using an ultrasonic homogenizer "US-1200T" (manufactured by Nippon Seiki Seisakusho) at a frequency of 20 kHz, output setting of 3, and tuning setting of 6.

[0041] The toner dispersion is separated by centrifuging it under the following conditions in a centrifuge "Model H-900" (manufactured by Kokusan). Rotor: PC-400 (radius 18.1 cm) Rotation speed: 1200 rpm (292 G) Time: 10 minutes

[0042] After centrifugation, 40 mL of the supernatant is collected. At this time, a pipette is used to carefully collect the supernatant, taking care not to include any of the settled toner base particles.

[0043] The volumetric particle size of the external additive contained in the collected supernatant is measured using a flow particle image analyzer "FPIA-2100" (manufactured by Sysmex Corporation), whereby the volumetric particle size distribution and the volumetric average particle size can be determined.

[0044] The measurement range is 0.6 to 400 μm. Since external additives other than the lubricant added to the toner base particles have a particle size of 0.6 μm or less, measurement in the range of 0.6 to 400 μm does not measure external additives other than the lubricant, and the particle size distribution measured in this measurement range corresponds to the particle size distribution of the lubricant.

[0045] FIG. 1 is a diagram illustrating an example of a volumetric particle size distribution of a lubricant having peaks on the small particle side and the large particle side, where a is an example of the particle size distribution of a lubricant conventionally added to toner base particles as an external additive. b is an example of a volumetric particle size distribution of a lubricant according to the present invention having two peaks on the small particle side and the large particle side, where P1 is the peak on the small particle side and P2 is the peak on the large particle side. D indicates the particle size at the minimum value of the particle size distribution curve. The content ratio is determined by dividing the lubricant into the small particle side and the large particle side from this minimum particle size D. In other words, each content ratio is a value obtained by dividing the volumetric particle size distribution of the lubricant shown in FIG. 1 into two, the small particle side and the large particle side, at the minimum particle size D.

[0046] Fig. 2 shows the integrated value of the frequency of the volumetric particle size distribution of the lubricant, and is a diagram for explaining the content ratio of lubricants having a peak on the small particle size side and lubricants having a peak on the large particle size side. Here, the integrated frequency value at particle size D, the minimum value of the particle size distribution (the intersection with D), represents the content ratio of lubricants having a peak on the small particle size side.

[0047] The lubricant according to the present invention preferably has a volumetric particle size distribution with two peaks, one on the small particle side and one on the large particle side, and the content of the lubricant with the peak on the small particle side is 50 to 70 mass % of the total lubricant.

[0048] The respective content ratios are values ​​obtained by dividing the volumetric particle size distribution of the lubricant shown in FIG. 1 into two parts, the small particle size side and the large particle size side, at the minimum particle size D.

[0049] The lubricant used in the present invention is preferably a particle containing a fatty acid metal salt as a main component from the viewpoint of spreadability on the photoreceptor, and further preferably has a Mohs hardness of 2 or less. Here, the "main component" refers to the component that has the largest mass ratio among the constituent components.

[0050] The fatty acid metal salt is preferably a salt of a metal selected from zinc, calcium, magnesium, aluminum, and lithium. Of these, fatty acid zinc, fatty acid lithium, or fatty acid magnesium is 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 fewer carbon atoms can prevent the melting point of the fatty acid metal salt from becoming too high, thereby achieving good fixability. The fatty acid is particularly preferably stearic acid.

[0051] The fatty acid metal salt particles used in the present invention are preferably particles containing zinc stearate as a main component, particles containing calcium stearate as a main component, or particles containing magnesium stearate as a main component, and among these, particles containing zinc stearate as a main component are particularly preferred because they have a small adhesive force with the toner base particles and can be easily transferred to the photoreceptor even with a small amount added.

[0052] In the present invention, it is preferable to use two types of lubricants having different average particle diameters so that the particle size distribution of the lubricant contained in the toner has two peaks, one on the small particle side and one on the large particle side. In this case, the components of the two types of lubricants having different average particle diameters may be the same or different.

[0053] The content of the lubricant in the toner is preferably 0.01 to 0.5 parts by mass relative to 100 parts by mass of the toner base particles, in order to obtain a sufficient lubricating effect within this range.

[0054] <2.2 Toner base particles> Known toner base particles can be used as the toner base particles. Specifically, such toner base particles are composed of toner base particles containing at least a binder resin and a colorant. Furthermore, the toner base particles can further contain other components such as a release agent and a charge control agent, as necessary.

[0055] The volume-based average particle size of the toner base particles is preferably within the range of 5.0 to 8.0 μm. When the volume-based average particle size of the toner base particles is within this range, high-definition images can be obtained.

[0056] The average circularity (shape factor) of the toner base particles is preferably 0.930 to 0.990, more preferably 0.955 to 0.980, from the viewpoint of improving flowability.

[0057] (Method for measuring the average circularity and volume-based average particle size of toner base particles) The average circularity and volume-based average particle size of the toner base particles can be measured using, for example, a flow particle image analyzer "FPIA-2100" (manufactured by Sysmex Corporation). Specifically, the toner is mixed in an aqueous solution containing a surfactant, and then dispersed by ultrasonic dispersion treatment for 1 minute. Then, using the "FPIA-2100" (manufactured by Sysmex Corporation), an image is taken under measurement conditions in HPF (high magnification imaging) mode at an appropriate concentration of 3,000 to 10,000 HPF detection particles, and the average circularity and volume-based average particle size can be measured.

[0058] Regarding the circularity, the circularity of each toner base particle is calculated by the following formula, and the average circularity is calculated: Here, the "circle equivalent diameter" refers to the diameter of a circle having the same area as the particle image. Circularity = Perimeter of a circle calculated from the equivalent diameter / Perimeter of a particle's projected image

[0059] (binder resin) It is preferable to use a thermoplastic resin as the binder resin constituting the toner base particles.

[0060] As such a binder resin, any binder resin generally used to form toner base particles can be used without any particular limitation, and specific examples thereof include styrene-based resins, acrylic-based resins (such as alkyl acrylates and alkyl methacrylates), styrene-acrylic copolymer resins, polyester resins, silicone resins, olefin-based resins, amide resins, and epoxy resins.

[0061] Among these, styrene resins, acrylic resins, styrene-acrylic copolymer resins, and polyester resins are preferred because they have low viscosity and high sharp melting properties. As the main resin, it is preferable to use styrene-acrylic copolymer resins in an amount of 50% or more. These resins can be used alone or in combination of two or more.

[0062] Examples of polymerizable monomers that can be used to obtain the binder resin include styrene-based monomers such as styrene, methylstyrene, methoxystyrene, butylstyrene, phenylstyrene, and chlorostyrene; acrylic acid ester-based monomers such as methyl acrylate, ethyl acrylate, butyl acrylate, and ethylhexyl acrylate; methacrylic acid ester-based monomers such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and ethylhexyl methacrylate; and carboxylic acid-based monomers such as acrylic acid, methacrylic acid, and fumaric acid.

[0063] These can be used alone or in combination of two or more.

[0064] From the viewpoint of low-temperature fixability, the binder resin constituting the toner base particles preferably has a glass transition temperature (Tg) of 30 to 50° C. If the glass transition temperature is within this range, low-temperature fixability and heat-resistant storage stability are good.

[0065] The glass transition temperature of the binder resin can be measured using a Diamond DSC (manufactured by PerkinElmer).

[0066] The measurement procedure involves sealing 3.0 mg of binder resin in an aluminum pan and setting it in a holder. An empty aluminum pan is used as a reference. The measurement conditions are a measurement temperature of 0 to 200°C, a temperature increase rate of 10°C / min, a temperature decrease rate of 10°C / min, and temperature control of heat-cool-heat (Heat-Cool-Heat), and analysis is performed based on the data from the second heating (2nd Heat).

[0067] The glass transition temperature is determined by drawing an extension of the baseline before the rise of the first endothermic peak and a tangent line showing the maximum slope between the rise of the first peak and the peak apex, and the intersection of these lines is indicated as the glass transition point.

[0068] The glass transition temperature (Tg) of the toner base particles is measured by the same method as above, using the toner base particles as a measurement sample.

[0069] Furthermore, the softening temperature of the binder resin is preferably 80 to 130° C., and more preferably 90 to 120° C. The softening temperature can be measured, for example, by a flow tester “CFT-500D” (manufactured by Shimadzu Corporation).

[0070] The softening temperature is measured, for example, as follows.

[0071] First, in an environment of 20±1°C temperature and 50±5%RH relative humidity, 1.1g of sample was placed in a petri dish, flattened, and left for 12 hours or more. After that, it was pressed into a molder "SSP-10A" (Shimadzu Corporation) at a pressure of 3820kg / cm 2 This 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 melting temperature measurement method with an offset value set to 5 mm. 0ffset is taken as the softening temperature of the sample.

[0072] The softening temperature of the toner base particles is measured using the sample as the toner base particles in the same manner as above.

[0073] (coloring agent) As the colorant constituting the toner base particles, known inorganic or organic colorants can be used.

[0074] The amount of the colorant added is in the range of 1 to 30% by mass, preferably 2 to 20% by mass, based on the total mass of the toner base particles.

[0075] (mold release agent) The toner base particles may contain a release agent, such as hydrocarbon waxes (polyethylene wax, oxidized polyethylene wax, polypropylene wax, oxidized polypropylene wax, etc.), carnauba wax, fatty acid ester wax, sazol wax, rice wax, candelilla wax, jojoba oil wax, and beeswax.

[0076] The content of the release agent in the toner base particles is preferably in the range of 1 to 30 parts by mass, more preferably in the range of 5 to 20 parts by mass, relative to 100 parts by mass of the binder resin.

[0077] (charge control agent) The toner base particles may contain a charge control agent, such as a metal complex of a salicylic acid derivative with zinc or aluminum (salicylic acid metal complex), a calixarene compound, an organic boron compound, or a fluorine-containing quaternary ammonium salt compound.

[0078] The content of the charge control agent in the toner base particles is preferably within a range of 0.1 to 5.0 parts by mass relative to 100 parts by mass of the binder resin.

[0079] (Method for producing toner base particles) Methods for producing the toner base particles include a kneading and pulverizing method, a suspension polymerization method, an emulsion aggregation method, a solution suspension method, a polyester elongation method, and a dispersion polymerization method.

[0080] Among these, it is preferable to employ the emulsion aggregation method from the viewpoints of uniformity of particle size, controllability of shape, and ease of formation of a core-shell structure, which are advantageous for high image quality and high stability.

[0081] The emulsion aggregation method is a method for producing toner base particles by mixing a dispersion of resin fine particles dispersed with a surfactant and a dispersion stabilizer with a dispersion of toner base particle constituents such as colorant fine particles as needed, adding an aggregating agent to aggregate the particles to a desired toner particle size, and then, or simultaneously with the aggregation, fusing the resin fine particles together to control the shape.

[0082] Here, the resin microparticles may optionally contain internal additives such as a release agent and a charge control agent, and may also be composite particles formed of multiple layers consisting of two or more layers made of resins with different compositions.

[0083] Furthermore, from the viewpoint of toner structure design, it is also preferable to add different types of resin particles during aggregation to form toner base particles with a core-shell structure.

[0084] The resin microparticles can be produced by, for example, emulsion polymerization, mini-emulsion polymerization, phase inversion emulsification, etc., or by a combination of several production methods. When an internal additive is to be contained in the resin microparticles, it is preferable to use the mini-emulsion polymerization method.

[0085] <2.3 External additives other than lubricants> In addition to the lubricant, the toner particles preferably contain fine particles such as known inorganic fine particles or organic fine particles on their surfaces as external additives, from the viewpoint of improving the chargeability and flowability of the toner. As the inorganic fine particles, it is preferable to use inorganic oxide fine particles such as silica, titania, and alumina, and further it is preferable that these inorganic fine particles have been hydrophobized with a silane coupling agent, a titanium coupling agent, or the like.

[0086] As the organic fine particles, polymers such as polystyrene, polymethyl methacrylate, and styrene-methyl methacrylate copolymers can be used.

[0087] The total content of the inorganic fine particles and organic fine particles is preferably within a range of 0.05 to 5 parts by mass, and more preferably within a range of 0.1 to 3 parts by mass, per 100 parts by mass of the toner base particles.

[0088] (Metal oxide fine particles) The toner particles according to the present invention preferably contain metal oxide fine particles having a high abrasive effect as an external additive for the purpose of further enhancing the abrasive effect on the surface of the photoreceptor.

[0089] The metal oxide particles accumulate on the tip of the cleaning blade and act as an abrasive to refresh the surface of the photoreceptor. They also polish away excess lubricant spread on the photoreceptor, suppressing the occurrence of black dot-like image defects on the photoreceptor surface. They also have the effect of removing discharge products and controlling the fluidity and chargeability of toner.

[0090] As the metal oxide fine particles, silica fine particles, alumina fine particles, cerium oxide fine particles, calcium titanate fine particles, or strontium titanate fine particles having a number-average primary particle size in the range of 100 to 300 nm are preferred, and among these, calcium titanate fine particles or strontium titanate fine particles are particularly preferred.

[0091] The content of the metal oxide fine particles is preferably in the range of 0.05 to 5 parts by mass, and more preferably in the range of 0.1 to 3 parts by mass, relative to 100 parts by mass of the toner base particles.

[0092] From the viewpoint of heat-resistant storage property and environmental stability, the metal oxide fine particles are preferably those whose surfaces have been modified with a silane coupling agent, a titanium coupling agent, a higher fatty acid, a silicone oil, or the like.

[0093] <2.4 Adding external additives> The external additive may be added in the form of a powder to dried toner base particles by a dry method, and the mixing device may be a mechanical mixer such as a Henschel mixer or a coffee mill.

[0094] In the present invention, it is preferable to add and mix the lubricant in two stages to control the particle size distribution of the lubricant. Specifically, it is preferable to first add and mix a lubricant having a peak on the small particle size side, and then add and mix a lubricant having a peak on the large particle size side. External additives other than the lubricant, such as metal oxide fine particles, may be added and mixed in any of the two stages.

[0095] <2.5 Developer> The toner particles according to the present invention can be used in the image forming system of the present invention as a magnetic or non-magnetic single-component developer, or they can be mixed with carrier particles to form a two-component developer. When using this toner as a two-component developer, magnetic particles made of conventionally known materials such as iron, ferrite, magnetite, lead, aluminum, and alloys thereof can be used as the carrier particles, with ferrite particles being particularly preferred. Furthermore, resin-coated carrier particles (coated carrier) particles, in which the surfaces of magnetic particles are coated with a coating agent such as resin, or binder-type carrier particles, in which magnetic fine powder is dispersed in a binder resin, can also be used as the carrier particles.

[0096] The coating resin constituting the resin-coated carrier particles is not particularly limited, and examples thereof include olefin resins, styrene resins, styrene-acrylic resins, acrylic resins, silicone resins, ester resins, and fluororesins. Furthermore, the binder resin constituting the binder-type carrier particles is not particularly limited, and known resins can be used, such as styrene-acrylic resins, polyester resins, fluororesins, and phenolic resins. Among these, resin-coated carrier particles coated with styrene-acrylic resins and acrylic resins are preferred from the viewpoints of chargeability and durability.

[0097] The carrier particles preferably have a volume average particle size in the range of 20 to 100 μm, more preferably 25 to 80 μm, in order to obtain high-quality images and suppress carrier adhesion. The volume average particle size of the carrier particles can be measured typically using a laser diffraction particle size distribution analyzer "HELOS" (manufactured by Sympatec Co., Ltd.) equipped with a wet disperser.

[0098] <3 Cleaning Method> The cleaning means according to the present invention is characterized by comprising a brush roller having a plurality of pile bundles, and a cleaning blade provided downstream of the brush roller in the rotation direction of the photosensitive member.

[0099] Fig. 3 is a schematic diagram of the cleaning unit, which includes a brush roller 120 and a cleaning blade 121 provided downstream of the brush roller 120 in the rotation direction of the photoreceptor 111 (the direction of the arrow in the figure).

[0100] <3.1 Brush Roller> The brush roller according to the present invention has a plurality of pile bundles, and the pile bundle fineness [dtex] is X, and the pile density [KF / inch 2 ] is defined as Y, the following formulas (1) and (2) are satisfied. Formula (1): 100≦Y≦250 Formula (2): 0.7≦X / Y≦2.2

[0101] In the present invention, "pile" refers to fibers implanted in a base fabric and protruding from the base fabric, and "pile bundle" refers to a bundle of pile fibers implanted in the same opening of the base fabric.

[0102] The main function of the brush roller of the present invention is to uniformly distribute the lubricant on the photoreceptor. Specifically, the brush roller collects excess lubricant on the photoreceptor, and distributes small-particle lubricant, which tends to be present in large amounts in toner-application areas, to non-toner-application areas, and conversely, distributes large-particle lubricant, which tends to be present in large amounts in non-toner-application areas, to non-toner-application areas, thereby uniformly distributing the lubricant on the photoreceptor. This makes it possible to suppress image memory.

[0103] The brush roller has a plurality of pile bundles, and is not particularly limited as long as it satisfies the above formulas (1) and (2), but it can have, for example, a cylindrical shaft to which a base fabric with pile fibers implanted therein is fixed with adhesive, etc. Various techniques can be used to implant the pile fibers into the base fabric, such as pile weaving and electrostatic implantation.

[0104] In the present invention, the "pile bundle fineness [dtex]" represented by X refers to the fineness of the pile bundle, and is a value that can be calculated by the following formula. Pile bundle fineness [dtex] = fineness of one pile [dtex] x number of piles per pile bundle

[0105] In the present invention, the "pile density [KF / inch]" represented by Y is 2 ]" means 1 inch 2 This refers to the number of piles per inch. Here, "KF" is a unit where "1000 piles" equals "1KF". Therefore, for example, 100KF / inch 2 That is, 1 inch 2 The number of piles per inch is 100,000 (i.e., 100,000 piles / inch 2 In the case of loop piles, one loop is considered to be two piles.

[0106] The above values ​​can be confirmed, for example, by loosening the pile bundles to make them easier to observe, and observing them using an optical microscope at an appropriate magnification.

[0107] By setting the pile bundle fineness X and pile density Y within the ranges that satisfy the above formulas (1) and (2), the brush roller according to the present invention can optimize the range of movement per pile bundle, the abrasive force, and the probability of contact between the pile and the lubricant, thereby enhancing the recovery and diffusion effect of the lubricant, thereby achieving a uniform distribution of the lubricant on the photoreceptor.

[0108] If the pile density Y is less than 100, the abrasive force becomes too small, resulting in a reduced recovery and diffusion effect of the lubricant. Also, if the pile density Y is more than 250, the working area per pile bundle becomes too small, resulting in a reduced diffusion effect of the lubricant.

[0109] If X / Y is less than 0.7, the working area per pile bundle becomes too small, resulting in a reduced lubricant diffusion effect. Also, if X / Y is greater than 2.2, the probability of contact between the pile and the lubricant becomes too small, resulting in a reduced lubricant recovery and diffusion effect.

[0110] The Young's modulus of the pile is adjusted to an appropriate range for the abrasive force, preferably within the range of 25 to 70 cN / dtex, which makes the abrasive force appropriate and further improves the recovery and diffusion effect of the lubricant.

[0111] The Young's modulus of the pile can be measured, for example, using a thermomechanical analyzer, TMA / SS6000, manufactured by Seiko Instruments Inc. The measurement ambient temperature is 25°C. The measurement sample is a set of multiple piles, each 10 mm or longer, with a total mass of 0.5 mg per 10 mm of length. The piles are arranged in parallel and mounted with a chuck distance of 10 mm, and a constant load of 0.73 mN / dtex is applied. A stress-strain curve is then obtained under conditions of 240 mN / min, and the slope of the tangent to the curve at a strain of 0.1% is taken as the Young's modulus.

[0112] The length of the pile is not particularly limited, but is preferably within the range of 2.5 to 3.5 mm from the viewpoint of the lubricant recovery and diffusion effect.

[0113] The fineness of each pile is not particularly limited, but is preferably within the range of 2.2 to 6.6 dtex from the viewpoint of the recovery and diffusion effect of the lubricant.

[0114] The pile material is not particularly limited, but examples thereof include synthetic resins such as polyester, acrylic, 6-nylon, 12-nylon, vinylon, and aramid, and mixtures of two or more of these.

[0115] The pile shape is not particularly limited, and for example, a loop pile in which the pile is left as a loop, or a cut pile in which the loops are cut to make a straight pile can be used.

[0116] The brush roller preferably rotates on an axis parallel to the axis of rotation of the photoreceptor. The rotation direction may be either with the direction (the surface moves in the same direction) or counter-direction (the surface moves in the opposite direction) relative to the rotation direction of the photoreceptor. However, from the viewpoint of the lubricant diffusion effect, the with direction is preferred.

[0117] The rotation speed of the brush roller is not particularly limited, but is preferably within the range of 300 to 900 rpm from the viewpoint of the lubricant diffusion effect.

[0118] The brush roller may be configured to be able to apply a voltage of the opposite polarity to the residual toner in order to improve the effect of collecting the residual toner.

[0119] <3.2 Cleaning blade> The cleaning blade according to the present invention will be described with reference to Fig. 3. Cleaning blade 121 shown in Fig. 3 is supported by support member 122, and is disposed such that the tip of cleaning blade 121 faces in the opposite direction (counter direction) to the rotation direction of photoreceptor 111 at contact portion C with the surface of photoreceptor 111.

[0120] The cleaning blade 121 according to the present invention has an edge angle θ eIt is preferable that the edge angle θ is in a range of 90 to 130 degrees. e This refers to the angle of the edge line at the contact point C with the surface of the photosensitive member 111.

[0121] Edge angle θ e When the wedge angle θ3 is 90° or more, a shearing action that cleaves and spreads the layered crystals of the lubricant is obtained, thereby improving the surface lubricity. The wedge angle θ3 refers to the angle between the cleaning blade 121 and the ridgeline on the upstream side of the rotation direction of the photoreceptor 111.

[0122] Edge angle θ e By keeping the wedge angle θ3 at 130° or less, the abrasiveness is moderate and lubrication is effectively achieved. In addition, the force with which the toner particles push the blade vertically upward is not too large, so cleaning defects are less likely to occur.

[0123] In addition, the edge angle θ e When the angle is within the range of 90 to 130°, stick-slip vibration of the cleaning blade is reduced, and the toner particles are allowed to pass through more easily, resulting in improved cleaning performance.

[0124] Edge angle θ e From the viewpoint of effectively improving the surface lubricity and cleaning property, the angle is preferably 95° or more and 110° or less.

[0125] The cleaning blade 121 according to the present invention is preferably pressed against the surface of the photoreceptor 111 so that the effective contact angle θ1 is within a range of 7 to 20°. The effective contact angle θ1 refers to the angle between the cleaning blade 121 and the ridgeline of the photoreceptor 111 on the downstream side in the rotation direction.

[0126] By making the effective contact angle θ1 7° or more, the wedge angle θ3 becomes small, which produces a shearing action that cleaves and spreads the layered crystals of the lubricant, thereby improving the surface lubricity.

[0127] By keeping the effective contact angle θ1 at 20° or less, the wedge angle θ3 does not become too small, resulting in appropriate abrasiveness and effective lubrication. In addition, the force with which the toner particles push the blade vertically upward is not too strong, making cleaning defects less likely to occur.

[0128] From the viewpoint of effectively improving the surface lubricity, the effective contact angle θ1 is preferably 9° or more and 17° or less.

[0129] Edge angle θ e The effective contact angle θ1 can be determined by calculating the deflection using the cross-sectional shape of the cleaning blade 121 and physical properties such as Young's modulus of the material.

[0130] From the viewpoint of wear resistance and moldability, the cleaning blade 121 is preferably made of polyurethane. Examples of polyurethane include those obtained by reacting polyol, polyisocyanate, and, if necessary, a crosslinking agent.

[0131] The cleaning blade 121 may have a single layer structure, or may have a multi-layer structure in which a support layer and a contact layer are laminated.

[0132] The hardness of the cleaning blade 121 is preferably within the range of 65 to 85° as defined by JIS-A. If the hardness is 65° or more, the cleaning blade 121 is less likely to be retracted, and the wedge angle θ3 does not become too small. If the hardness is 85° or less, the surface pressure does not become too high, the abrasive force does not become too strong, and the lubricant is less likely to be removed, thereby achieving a sufficient lubricating effect.

[0133] The rebound resilience of the cleaning blade 121 is preferably within a range of 10 to 40°. If the rebound resilience is within the above range, vibration is appropriately suppressed, the wedge angle θ3 is stabilized, and the shearing action of the fatty acid metal salt can be more effectively exerted.

[0134] The free length L of the cleaning blade 121 is preferably within a range of 8.5 to 11.5 mm, and the thickness of the cleaning blade 121 is preferably within a range of 1.7 to 2.5 mm.

[0135] From the viewpoint of preventing incomplete wiping and curling, the contact force of the cleaning blade 121 is preferably within the range of 12 to 30 N / m. If the contact force is 12 N / m or more, there is no risk of incomplete wiping, and if it is 30 N / m or less, there is no risk of curling.

[0136] The support member 122 may be a conventionally known material, such as a rigid metal, an elastic metal, plastic, or ceramic. Of these, a rigid metal is preferred.

[0137] <4 Electrophotographic photoreceptor> The layer structure of the electrophotographic photoreceptor according to the present invention is not particularly limited, but it is preferable that the electrophotographic photoreceptor has a surface protective layer from the viewpoint of abrasion resistance. The electrophotographic photoreceptor having a surface protective layer can have the layer structures shown in the following (1) to (4), for example.

[0138] (1) A layer structure in which a photosensitive layer (charge generating layer and charge transport layer) and a surface protective layer are sequentially laminated on a conductive support. (2) A layer structure in which a photosensitive layer (a single layer containing a charge transport material and a charge generating material) and a surface protective layer are sequentially laminated on a conductive support. (3) A layer structure in which an intermediate layer, a photosensitive layer (a charge generating layer and a charge transport layer), and a surface protective layer are laminated in this order on a conductive support. (4) A layer structure in which an intermediate layer, a photosensitive layer (a single layer containing a charge transport material and a charge generation material), and a surface protection layer are laminated in this order on a conductive support.

[0139] As in the above example, the photosensitive layer may be a single layer containing a charge generating material and a charge transporting material, or may be a functionally separated photosensitive layer consisting of two layers: a charge generating layer containing a charge generating material and a charge transporting layer containing a charge transporting material.

[0140] <4.1 Surface protective layer> The surface protective layer preferably contains at least a binder resin and a charge transport material, and more preferably further contains metal oxide particles.

[0141] Although resins such as polycarbonate can be used as the binder resin, it is preferable to use a cured resin from the viewpoint of abrasion resistance. The term "cured resin" refers to a resin obtained by curing at least a polymerizable compound.

[0142] Although photoreceptors with low abrasion resistance have a short lifespan, the difference in the amount of lubricant attached does not increase as the surface wears, and they are less likely to develop image memory. In contrast, photoreceptors with high abrasion resistance are less susceptible to image memory due to their low abrasion. However, the image forming system of the present invention can suppress image memory through the configuration of the toner particles and brush roller, so the photoreceptor can be configured with a priority on abrasion resistance. In other words, by including a cured resin in the surface protective layer, it is possible to achieve a high level of both abrasion resistance and suppression of image memory during long-term use of the photoreceptor.

[0143] The polymerizable compound is preferably a monomer that polymerizes (cures) when exposed to actinic rays such as ultraviolet rays or electron beams to become a resin generally used as a binder resin for a photoreceptor, such as polystyrene or polyacrylate. In particular, styrene-based monomers, acrylic-based monomers, methacrylic-based monomers, vinyltoluene-based monomers, vinyl acetate-based monomers, and N-vinylpyrrolidone-based monomers are preferred.

[0144] Among these, crosslinkable radical polymerizable compounds (radical polymerizable monomers or oligomers thereof) having an acryloyl group (CH2=CHCO-) ​​or a methacryloyl group (CH2=CCH3CO-) are particularly preferred because they can be cured with a small amount of light or in a short time.

[0145] The radical polymerizable compounds may be used alone or in combination. These polymerizable compounds may be used as monomers or as oligomers.

[0146] Examples of radical polymerizable compounds are shown below. The terms "Ac group number (acryloyl group number)" and "Mc group number (methacryloyl group number)" used below represent the number of acryloyl groups and the number of methacryloyl groups, respectively.

[0147] [ka]

[0148] [ka]

[0149] [ka]

[0150] [ka]

[0151] [ka]

[0152] [ka]

[0153] [ka]

[0154] However, in the above, R is represented as follows.

[0155] [ka]

[0156] [ka]

[0157] [ka]

[0158] [ka]

[0159] [ka]

[0160] [ka]

[0161] [ka]

[0162] [ka]

[0163] However, in the above, R' is represented as follows.

[0164] [ka]

[0165] Among the above, more preferred polymerizable compounds for use in the present invention include compounds having a quaternary carbon atom (branched structure) substituted with a carbon atom, and having this branched structure as a central structure and three or more acryloyl groups at the terminals thereof, specifically groups Ac-1 to Ac-6, Ac-31, Ac-37, and Ac-38, which have a trimethylolpropane skeleton, a pentaerythritol skeleton, or a dipentaerythritol skeleton; compounds having a quaternary carbon atom (branched structure) substituted with a carbon atom, and having this branched structure as a central structure and three or more methacryloyl groups at the terminals thereof, specifically groups Mc-1 to Mc-6, Mc-31, Mc-37, and Mc-38, which have a trimethylolpropane skeleton, a pentaerythritol skeleton, or a dipentaerythritol skeleton; and groups Mc-9 and Mc-11, which have an isocyanuric ring skeleton and three or more methacryloyl groups at the terminals thereof.

[0166] The radical polymerizable compound preferably has three or more functional groups (reactive groups). Two or more radical polymerizable compounds may be used in combination. Even in this case, it is preferable to use 50% by mass or more of radical polymerizable compounds having three or more functional groups. The curable reactive group equivalent, i.e., the "molecular weight of curable functional groups / number of functional groups," is preferably 1,000 or less, more preferably 500 or less. This increases the crosslink density and improves abrasion resistance.

[0167] When reacting the radical polymerizable compound used in the present invention, a method of reacting by electron beam cleavage, or a method of reacting by light or heat after adding a radical polymerization initiator, etc. can be used. Either a photopolymerization initiator or a thermal polymerization initiator can be used as the polymerization initiator. Furthermore, both a photopolymerization initiator and a thermal initiator can be used in combination.

[0168] As the radical polymerization initiator for these photocurable compounds, a photopolymerization initiator is preferred, and among them, an alkylphenone compound or a phosphine oxide compound is preferred. In particular, a compound having an α-hydroxyacetophenone structure or an acylphosphine oxide structure is preferred. In addition, examples of compounds that initiate cationic polymerization include ionic polymerization initiators and nonionic polymerization initiators. Examples of ionic polymerization initiators include aromatic onium compounds such as diazonium, ammonium, iodonium, sulfonium, and phosphonium, such as B(C6F5)4. - , PF6 - , AsF6 - , SbF6 - , and CF3SO3 - Examples of the nonionic polymerization initiator include sulfonates that generate sulfonic acid, halides that generate hydrogen halide, and iron-allene complexes. Among these, the nonionic polymerization initiators, sulfonates that generate sulfonic acid, and halides that generate hydrogen halide, are particularly preferred.

[0169] Examples of photopolymerization initiators that are preferably used are shown below.

[0170] Examples of α-aminoacetophenones

[0171] [ka]

[0172] Examples of α-hydroxyacetophenone compounds

[0173] [ka]

[0174] Examples of acylphosphine oxide compounds

[0175] [ka]

[0176] Other examples of radical polymerization initiators

[0177] [ka]

[0178] On the other hand, as the thermal polymerization initiator, ketone peroxide compounds, peroxyketal compounds, hydroperoxide compounds, dialkyl peroxide compounds, diacyl peroxide compounds, peroxydicarbonate compounds, peroxyester compounds, etc. are used, and these thermal polymerization initiators are disclosed in company product catalogs, etc.

[0179] These polymerization initiators may be used alone or in combination of two or more. The content of the polymerization initiator is preferably within a range from 0.1 to 20 parts by mass, and more preferably within a range from 0.5 to 10 parts by mass, per 100 parts by mass of the polymerizable compound.

[0180] The charge transport material contained in the surface protective layer may be a known charge transport material, such as 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, benzidine derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene, poly-9-vinylanthracene, and triphenylamine derivatives. Two or more of these may be used in combination.

[0181] The charge transport material is preferably a compound having a structure represented by the following general formula (1): Compounds having a structure represented by the following general formula (1) do not exhibit absorption in the short wavelength region, and many of them have a molecular weight of 450 or less, allowing them to penetrate into the voids in the binder resin of the surface protective layer. This allows for smooth injection of charge carriers from the charge transport layer without reducing the abrasion resistance of the surface protective layer, and allows charge to be transported to the surface of the surface protective layer without causing an increase in residual charge or the occurrence of transfer memory.

[0182] [ka]

[0183] [In general formula (1), R1, R2, R3, and R4 each independently represent a hydrogen atom, an alkyl group having 1 to 7 carbon atoms, or an alkoxy group having 1 to 7 carbon atoms; k, l, and n represent integers of 1 to 5; and m represents an integer of 1 to 4. When k, l, m, or n is plural, these plural groups may be the same or different.]

[0184] Examples of the alkyl group having 1 to 7 carbon atoms include a methyl group, an ethyl group, a propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, an n-hexyl group, a 3-methylpentan-2-yl group, a 3-methylpentan-3-yl group, a 4-methylpentyl group, a 4-methylpentan-2-yl group, a 1,3-dimethylbutyl group, a 3,3-dimethylbutyl group, a 3,3-dimethylbutan-2-yl group, an n-heptyl group, a 1-methylhexyl group, a 3-methylhexyl group, a 4-methylhexyl group, a 5-methylhexyl group, a 1-ethylpentyl group, a 1-(n-propyl)butyl group, a 1,1-dimethylpentyl group, a 1,4-dimethylpentyl group, a 1,1-diethylpropyl group, a 1,3,3-trimethylbutyl group, and a 1-ethyl-2,2-dimethylpropyl group. Of these, alkyl groups having 1 to 5 carbon atoms are more preferred, with methyl, ethyl, propyl, n-butyl, and n-pentyl groups being even more preferred.

[0185] Examples of the alkoxy group having 1 to 7 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, an n-butoxy group, an isobutoxy group, a sec-butoxy group, a tert-butoxy group, an n-pentyloxy group, an isopentyloxy group, a neopentyloxy group, a 1,2-dimethyl-propoxy group, an n-hexyloxy group, a 3-methylpentan-2-yloxy group, a 3-methylpentan-3-yloxy group, a 4-methylpentyloxy group, a 4-methylpentan-2-yloxy group, a 1,3-dimethylbutyloxy group, a 3, Examples of the alkyl group include 3-dimethylbutyloxy, 3,3-dimethylbutan-2-yloxy, n-heptyloxy, 1-methylhexyloxy, 3-methylhexyloxy, 4-methylhexyloxy, 5-methylhexyloxy, 1-ethylpentyloxy, 1-(n-propyl)butyloxy, 1,1-dimethylpentyloxy, 1,4-dimethylpentyloxy, 1,1-diethylpropyloxy, 1,3,3-trimethylbutyloxy, and 1-ethyl-2,2-dimethylpropyloxy. Among these, an alkoxy group having 1 to 2 carbon atoms is more preferred, and a methoxy group is even more preferred.

[0186] In particular, it is preferable that at least one of R1, R2, R3, and R4 is a propyl group, a butyl group, or a pentyl group.

[0187] In particular, it is more preferable that R1 and R2 are each a hydrogen atom or a methyl group. It is more preferable that R3 is a hydrogen atom and R4 is an alkyl group having 1 to 5 carbon atoms. It is more preferable that k, l, m, and n are each 1.

[0188] Specific examples of compounds having the structure represented by general formula (1) are shown below.

[0189] [ka]

[0190] [ka]

[0191] [ka]

[0192] [ka]

[0193] [ka]

[0194] The charge transport material can be synthesized by a known synthesis method, for example, the method described in JP-A-2006-143720.

[0195] Examples of metal oxide particles contained in the surface protective layer include silica (silicon oxide), magnesium oxide, zinc oxide, lead oxide, alumina (aluminum oxide), zirconium oxide, tin oxide, titania (titanium oxide), niobium oxide, molybdenum oxide, and vanadium oxide, with tin oxide, titanium oxide, and zinc oxide being preferred.

[0196] The volume resistivity [Ω·cm] of the above metal oxide particles is 1×10 3 ~1×10 11 It is preferable that the range is 5×10 3 ~4×10 10 It is more preferable that the resistance is in the range of Ω·cm.

[0197] Volume resistivity (VR) refers to the electrical resistivity of the electricity flowing inside an object, and is a value expressed by the following formula. VR=(A / L)×R VR: Volume resistivity [Ω cm] A: Cross-sectional area of ​​the substance [cm 2 ] L: Distance between electrodes [cm] ρ: Electrical resistivity [Ω]

[0198] The volume resistivity VR [Ω cm] of metal oxide particles can be determined, for example, by filling a container with metal oxide particles having electrodes arranged in parallel with a distance of 0.2 cm between them, and measuring the DC electrical resistivity ρ [Ω] at a potential difference of 500 V between the electrodes using a Yokogawa Hewlett-Packard 4329A High Resistance Meter.

[0199] The metal oxide particles are preferably surface-modified with a surface modifier having a radically polymerizable functional group, particularly with a surface modifier having an acryloyl group or a methacryloyl group.

[0200] Examples of the surface modifier having an acryloyl group or a methacryloyl group include the compounds shown below.

[0201] 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)3Si(CH3)(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

[0202] [ka]

[0203] Among the above, S-4 to S-7, which are compounds having an ether-bonded acryloyl group and a terminal methoxy group, and S-12 to S-15 and S-24, which are compounds having an ether-bonded methacryloyl group and a terminal methoxy group, are more preferred.

[0204] The amount of surface modifier used to treat the metal oxide particles is preferably in the range of 0.1 to 200 parts by mass, more preferably 7 to 70 parts by mass, per 100 parts by mass of the metal oxide particles before treatment.

[0205] Hereinafter, a method for modifying the surface of metal oxide particles with a surface modifying agent having a radically polymerizable functional group will be described, taking titanium oxide particles as an example.

[0206] First, 100 parts by mass of titanium oxide particles and 0.1 to 200 parts by mass of a surface modifier having a radically polymerizable functional group are suspended in 50 to 5000 parts by mass of a solvent to prepare a slurry (a suspension of solid particles).

[0207] The slurry is placed in a wet media dispersion device and wet-pulverized, which simultaneously reduces the size of the titanium oxide particles and promotes surface modification of the titanium oxide particles. The solvent is then removed and the resulting particles are pulverized, yielding uniform titanium oxide particles that have been surface-modified with a surface-modifying compound (e.g., a silane compound).

[0208] The wet media dispersion apparatus described above is an apparatus that has a process of crushing, pulverizing, and dispersing agglomerates of metal oxide particles by filling a container with beads as media and rotating a stirring disk attached perpendicular to the rotation axis at high speed. The configuration of the apparatus is not critical as long as it can sufficiently disperse and surface-modify the metal oxide particles when surface-modifying them. Various types can be used, such as vertical and horizontal types, continuous and batch types. Specifically, sand mills, Ultraviscomills, pearl mills, grain mills, Dynomills, agitator mills, and dynamic mills can be used. These wet media dispersion apparatuses use grinding media (media) such as balls and beads to perform fine grinding and dispersion by impact crushing, friction, shear stress, shear stress, and other factors.

[0209] As the beads used in the wet media dispersion device, balls made from raw materials such as glass, alumina, zircon, zirconia, steel, and flint can be used, with zirconia and zircon being particularly preferred. The size of the beads is usually about 1 to 2 mm in diameter, with about 0.1 to 1.0 mm being preferred.

[0210] The discs and inner walls of the container used in the wet media dispersion type apparatus can be made of various materials such as stainless steel, nylon, and ceramic, but discs and inner walls of the container made of ceramics such as zirconia or silicon carbide are particularly preferred.

[0211] By the wet treatment described above, the titanium oxide particles can be surface-modified with a surface modifier having a radically polymerizable functional group.

[0212] The above description has been given using titanium oxide particles as an example. However, like titanium oxide, metal oxide particles such as alumina, zinc oxide, tin oxide, and silica also have hydroxy groups on their surfaces, and therefore, like titanium oxide, they can be surface-modified with a surface modifier having a radically polymerizable functional group.

[0213] The method for producing the metal oxide particles is not particularly limited, and particles produced by known production methods can be used.

[0214] The number average primary particle size of the metal oxide particles is preferably in the range of 1 to 300 nm, more preferably in the range of 3 to 100 nm, and even more preferably in the range of 5 to 40 nm.

[0215] The number average primary particle size of metal oxide particles can be calculated by taking a 10,000x magnification photograph using a scanning electron microscope (manufactured by JEOL Ltd.), randomly selecting 300 particles, scanning the photographic image (agglomerated particles excluded), and then using an automatic image processing and analysis device, LUZEX AP (Nireco Corporation), software version 1.32.

[0216] The surface protection layer according to the present invention can be formed, for example, by preparing a surface protection layer coating liquid by mixing a polymerizable compound, a polymerization initiator, a charge transport material, metal oxide particles, etc. in a solvent, applying the surface protection layer coating liquid onto the charge transport layer described below, and then drying and curing the liquid.

[0217] The proportion of the metal oxide particles in the surface protective layer is preferably 20 to 170 parts by mass, and more preferably 25 to 90 parts by mass, when the resin component in the surface protective layer is taken as 100 parts by mass. The resin component in the surface protective layer may be considered to be formed by the curing reaction of all of the polymerizable compounds contained in the surface protective layer coating liquid.

[0218] Furthermore, the content of the charge transport material in the surface protective layer is preferably in the range of 2 to 60 parts by weight, more preferably in the range of 10 to 50 parts by weight, and even more preferably in the range of 10 to 35 parts by weight, based on 100 parts by weight of the resin component of the surface protective layer.

[0219] The ratio of the charge transport material to the resin component in the surface protective layer may be considered to be the same as the ratio of the charge transport material to the polymerizable compound in the surface protective layer coating liquid.

[0220] The surface protective layer may further contain various antioxidants, and various lubricant particles may be added. For example, fluorine atom-containing resin particles may be added. As the fluorine atom-containing resin particles, one or more types are preferably selected from tetrafluoroethylene resin, trifluorochloroethylene resin, hexafluorochloroethylene propylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluorodichloroethylene resin, and copolymers thereof, with tetrafluoroethylene resin and vinylidene fluoride resin being particularly preferred.

[0221] Examples of solvents for forming the surface protective layer include, but are not limited to, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol, benzyl alcohol, toluene, xylene, methylene chloride, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine, and diethylamine.

[0222] Any solvent can be used as long as it can dissolve or disperse the polymerizable compound, metal oxide particles, and charge transport material. The method for producing the surface protective layer coating solution is also not particularly limited; the polymerizable compound, metal oxide particles, charge transport material, and various additives, if necessary, are added to the solvent and stirred until dissolved or dispersed. The amount of solvent is also not particularly limited; the amount can be adjusted appropriately so that the surface protective layer coating solution has a viscosity suitable for coating.

[0223] The surface protective layer coating solution can be applied by any known method such as dip coating, spray coating, spinner coating, bead coating, blade coating, beam coating, slide hopper method, and circular slide hopper method.

[0224] After coating the surface protective layer coating liquid, it is preferable to carry out natural drying or heat drying, and then irradiate with active rays to cause a curing reaction. Specifically, it is preferable to irradiate the coating film of the surface protective layer coating liquid with active rays to generate radicals to polymerize, and to form crosslinking bonds by intermolecular and intramolecular crosslinking reactions to harden, thereby producing a cured resin. As the active rays, ultraviolet rays and electron beams are more preferable, and ultraviolet rays are particularly preferable because they are easy to use.

[0225] Any light source that generates ultraviolet light can be used without limitation as the ultraviolet light source. For example, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, carbon arc lamps, metal halide lamps, xenon lamps, and flash (pulse) xenon lamps can be used. Irradiation conditions vary depending on the lamp, but the exposure dose of actinic rays is usually 5 to 500 mJ / cm. 2 , preferably 5 to 100 mJ / cm 2 The lamp power is preferably 0.1 kW to 5 kW, and particularly preferably 0.5 kW to 3 kW.

[0226] There are no particular limitations on the electron beam source, and generally, a curtain beam type electron beam accelerator is effectively used as the electron beam accelerator for electron beam irradiation, as it is relatively inexpensive and can provide high output. The acceleration voltage for electron beam irradiation is preferably in the range of 100 to 300 kV. The absorbed dose is preferably in the range of 0.5 to 10 Mrad.

[0227] The irradiation time for obtaining the required dose of actinic radiation is preferably within a range of 0.1 seconds to 10 minutes, and more preferably within a range of 0.1 seconds to 5 minutes from the viewpoint of work efficiency.

[0228] The timing of the step of drying the coating film of the surface protective layer coating solution is not limited to before irradiation with actinic rays, but may be after or during irradiation with actinic rays.

[0229] Drying conditions can be appropriately selected depending on the type of solvent, film thickness, etc. The drying temperature is preferably within the range of room temperature to 180° C., and particularly preferably within the range of 80° C. to 140° C. The drying time is preferably within the range of 1 minute to 200 minutes, and particularly preferably within the range of 5 minutes to 100 minutes.

[0230] The thickness of the surface protection layer is preferably in the range of 0.2 to 10 μm, and more preferably in the range of 0.5 to 6 μm.

[0231] <4.2 Conductive support> The conductive support used in the present invention may be any one that is conductive, and examples thereof include a metal such as aluminum, copper, chromium, nickel, zinc, or stainless steel formed into a drum or sheet shape, a metal foil such as aluminum or copper laminated onto a plastic film, a plastic film onto which aluminum, indium oxide, tin oxide, or the like is vapor-deposited, and a metal, plastic film, or paper on which a conductive layer is provided by applying a conductive substance alone or together with a binder resin.

[0232] 4.3 Middle class In the present invention, an intermediate layer having a barrier function and an adhesive function can be provided between the conductive support and the photosensitive layer. In consideration of preventing various failures, providing an intermediate layer is said to be a preferred embodiment.

[0233] The intermediate layer can be formed by dissolving a binder resin such as casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide, polyurethane, or gelatin in a known solvent and applying it by the same coating method as for the surface protective layer, such as dip coating. Of these, alcohol-soluble polyamide resins are preferred.

[0234] Furthermore, various conductive fine particles or metal oxide particles can be contained in the intermediate layer for the purpose of adjusting the resistance thereof, such as metal oxide particles of alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide, or ultrafine particles of tin-doped indium oxide, antimony-doped tin oxide, and zirconium oxide.

[0235] These metal oxide particles may be used alone or in combination of two or more types. When two or more types are mixed, they may be in the form of a solid solution or fused. The average particle size of such metal oxide particles is preferably 0.3 μm or less, more preferably 0.1 μm or less.

[0236] The solvent used to form the intermediate layer is preferably one that disperses inorganic particles well and dissolves binder resins, particularly polyamide resins. Specifically, alcohols having 1 to 4 carbon atoms, such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, and sec-butanol, are preferred because they have excellent solubility and coatability for polyamide resins. Furthermore, examples of co-solvents that can be used in combination with the solvents to improve storage stability and particle dispersibility and that provide favorable effects include benzyl alcohol, toluene, methylene chloride, cyclohexanone, and tetrahydrofuran.

[0237] The concentration of the binder resin in the coating liquid for forming the intermediate layer is appropriately selected according to the film thickness of the intermediate layer and the production speed.

[0238] The mixing ratio of the inorganic particles when dispersed is preferably within a range of 20 to 400 parts by mass, more preferably within a range of 50 to 350 parts by mass, per 100 parts by mass of the binder resin.

[0239] As a means for dispersing the inorganic particles, an ultrasonic disperser, a ball mill, a sand mill, a homomixer, or the like can be used, but the means is not limited to these.

[0240] To form the intermediate layer, a binder resin is dissolved in the above-mentioned solvent, inorganic fine particles are dispersed by the above-mentioned method, and the solution is then applied to a conductive support to a desired thickness. The applied layer is then dried to complete the intermediate layer. The drying method for the intermediate layer can be selected appropriately depending on the type of solvent and the film thickness, but thermal drying is preferred.

[0241] The thickness of the intermediate layer is preferably in the range of 0.1 to 15 μm, more preferably in the range of 0.3 to 10 μm.

[0242] 4.4 Charge generation layer The charge generating layer used in the present invention preferably contains a charge generating material and a binder resin, and is preferably formed by dispersing the charge generating material in a binder resin solution and applying the resulting solution.

[0243] Examples of charge-generating materials include, but are not limited to, azo pigments (such as Sudan Red and Diane Blue), quinone pigments (such as pyrenequinone and anthanthrone), indigo pigments (such as quinocyanine pigments, perylene pigments, indigo, and thioindigo), polycyclic quinone pigments (such as pyranthrone and diphthaloylpyrene), and phthalocyanine pigments. Polycyclic quinone pigments and titanyl phthalocyanine pigments are preferred. These charge-generating materials can be used alone or dispersed in a known resin.

[0244] The binder resin of the charge generating layer may be any known resin, including, but not limited to, polystyrene resin, polyethylene resin, polypropylene resin, acrylic resin, methacrylic resin, vinyl chloride resin, vinyl acetate resin, polyvinyl butyral resin, epoxy resin, polyurethane resin, phenolic resin, polyester resin, alkyd resin, polycarbonate resin, silicone resin, melamine resin, copolymer resins containing two or more of these resins (e.g., vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin), and polyvinyl carbazole resin. Polyvinyl butyral resin is preferred.

[0245] The charge generation layer is preferably formed by dispersing a charge generation material in a solution prepared by dissolving a binder resin in a solvent using a disperser to prepare a coating solution, applying the coating solution to a predetermined thickness using a coater, and drying the coating. The coating method can be the same as that for the surface protective layer described above.

[0246] Examples of solvents for dissolving and applying the binder resin used in the charge generating layer include, but are not limited to, toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexane, ethyl acetate, t-butyl acetate, methanol, ethanol, propanol, butanol, methyl cellosolve, 4-methoxy-4-methyl-2-pentanone, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine, and diethylamine.

[0247] As a means for dispersing the charge generating material, an ultrasonic disperser, a ball mill, a sand mill, a homomixer, or the like can be used, but the means is not limited to these.

[0248] The mixing ratio of the charge generating substance to the binder resin is preferably within a range of 1 to 600 parts by mass, and more preferably within a range of 50 to 500 parts by mass, per 100 parts by mass of the binder resin.

[0249] The occurrence of image defects can be prevented by filtering foreign matter and aggregates from the coating liquid for the charge generating layer before coating. The pigment can also be formed by vacuum deposition.

[0250] The thickness of the charge generating layer varies depending on the characteristics of the charge generating material, the characteristics and mixing ratio of the binder resin, etc., but is preferably in the range of 0.01 to 5 μm, more preferably in the range of 0.05 to 3 μm.

[0251] <4.5 Charge transport layer> The charge transport layer used in the photoreceptor according to the present invention preferably contains a charge transport material and a binder resin, and is preferably formed by dissolving the charge transport material in a binder resin solution and applying the solution.

[0252] The charge transport material contained in the charge transport layer may be a known charge transport material, such as 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, benzidine derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene, poly-9-vinylanthracene, and triphenylamine derivatives. Two or more of these may be used in combination.

[0253] The charge transport layer disposed under the surface protective layer preferably contains a charge transport material having a high ionization potential with the charge generating layer and the surface protective layer, a high mobility, and a long flight distance. The charge transport material used in the charge transport layer is preferably a charge transport material different from the compound having the structure represented by the general formula (1).

[0254] Preferred examples of charge transport materials that satisfy the above-mentioned properties and are used in photoreceptors for short-wave exposure such as with short-wave lasers are given below.

[0255] [ka]

[0256] Preferred examples of the charge transport material used in a photoreceptor for long-wave exposure using a long-wave laser or the like are given below.

[0257] [ka]

[0258] [ka]

[0259] The following compounds can also be suitably used as the charge transport material contained in the charge transport layer.

[0260] [ka]

[0261] The charge transport material can be synthesized by a known synthesis method, for example, the synthesis method described in JP-A Nos. 2010-26428 and 2010-91707.

[0262] The binder resin for the charge transport layer may be a known resin, such as polycarbonate resin, polyacrylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylate resin, and styrene-methacrylate copolymer resin, but polycarbonate resin is preferred. Furthermore, BPA, BPZ, dimethyl BPA, and BPA-dimethyl BPA copolymer are preferred in terms of crack resistance, abrasion resistance, and antistatic properties.

[0263] The charge transport layer is preferably formed by dissolving a binder resin and a charge transport material to prepare a coating solution, applying the coating solution to a predetermined thickness using a coating machine, and drying the coating. The coating method can be the same as that for the surface protective layer.

[0264] Examples of solvents for dissolving the binder resin and the charge transport material include, but are not limited to, toluene, xylene, methylene chloride, 1,2-dichloroethane, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, pyridine, and diethylamine.

[0265] The mixing ratio of the charge transport material to the binder resin is preferably within a range of 10 to 500 parts by weight, more preferably within a range of 20 to 250 parts by weight, per 100 parts by weight of the binder resin.

[0266] The thickness of the charge transport layer varies depending on the characteristics of the charge transport material, the characteristics of the binder resin, the mixing ratio, etc., but is preferably in the range of 5 to 40 μm, more preferably in the range of 10 to 30 μm.

[0267] The charge transport layer may contain an antioxidant, an electronic conductive agent, a stabilizer, silicone oil, etc. The antioxidant may be one described in JP-A-2000-305291, etc. The electronic conductive agent may be one described in JP-A-50-137543 and JP-A-58-76483, etc.

[0268] <5 Image forming device> As described above, in the image forming system of the present invention, the device section is particularly referred to as an “image forming apparatus.” That is, the image forming apparatus of the present invention is characterized by including an electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit, a transfer unit, and a cleaning unit.

[0269] Fig. 4 is a schematic diagram showing an example of the configuration of an image forming apparatus according to the present invention. The image forming apparatus 100 shown in Fig. 4 is called a tandem color image forming apparatus, and has four image forming units 110Y, 110M, 110C, and 110Bk, a paper feed conveying means 150, and a fixing means 170.

[0270] An original image reading device SC is disposed on the upper part of the main body of the image forming apparatus 100.

[0271] The image forming units 110Y, 110M, 110C, and 110Bk are arranged side by side in the vertical direction.

[0272] The image forming units 110Y, 110M, 110C, and 110Bk each include a rotating drum-shaped photosensitive member 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 photosensitive member in the outer circumferential surface area of ​​the photosensitive member.

[0273] Yellow (Y), magenta (M), cyan (C) and black (Bk) toner images are formed on the photoreceptors 111Y, 111M, 111C and 111Bk, respectively.

[0274] Note that Figure 4 is an explanatory schematic diagram mainly showing the positional relationship of each means of the image forming apparatus, and does not show the details of the cleaning means, but in the present invention, the cleaning means 119Y, 119M, 119C, and 119Bk have a brush roller and a cleaning blade, as explained above using Figure 3.

[0275] Since the details of the photosensitive member and the cleaning means are as described above, the remaining components will be described below. Note that when the drawings are used for explanation, the image forming unit 110Y will be used as an example.

[0276] The charging means is a means for uniformly charging the surface of the photoreceptor. Charging means include contact types such as charging rollers, charging brushes, and charging blades, and non-contact types such as corona chargers (corotron chargers, strochoton chargers, etc.). Contact types have the advantage of generating less harmful ozone gas during the charging process. Non-contact types have the advantage of being less prone to filming because they do not involve close-proximity discharge, as opposed to contact types.

[0277] The exposure unit is a unit that exposes the photosensitive member, which has been given a uniform potential by the charging unit, based on an image signal to form an electrostatic latent image corresponding to the image. Examples of the exposure unit include a unit consisting of an LED with light-emitting elements arranged in an array in the axial direction of the photosensitive member and an imaging element, and a laser optical system.

[0278] The developing means (developing machine) is a means for supplying toner to the surface of the photoconductor to develop the electrostatic latent image formed on the surface of the photoconductor to form a toner image. Specifically, the developing means 117Y shown in Fig. 4 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 photoconductor 111Y and the developing roller 118Y.

[0279] The rotation of the developing roller 118Y transports toner to the photoreceptor 111Y. Then, a thin layer of toner on the developing roller 118Y comes into contact with the photoreceptor 111Y to develop the electrostatic latent image on the photoreceptor 111Y. 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. The developing bias can be adjusted to a desired value by controlling the voltage applied to the developing roller 118Y.

[0280] An electric field is formed in a development section where the development roller 118Y and the photoconductor 111Y face each other due to a potential difference (development potential difference) between the development roller 118Y and the potential of the electrostatic latent image carried by the photoconductor 111Y. The toner in the developer transported to the development section by the rotation of the development roller 118Y moves due to the force exerted by the electric field and is attracted to the electrostatic latent image on the photoconductor 111Y. The electrostatic latent image carried by the photoconductor 111Y is visualized, and a toner image corresponding to the shape of the electrostatic latent image is formed on the surface of the photoconductor 111Y.

[0281] The transfer means is a means for transferring a toner image on a photosensitive member to a transfer body (intermediate transfer body or transfer material). The primary transfer roller 133Y shown in FIG. 4 transfers the toner image formed on the photosensitive member 111Y to the endless belt-like intermediate transfer body 131. The primary transfer roller 133Y is disposed in contact with the intermediate transfer body 131.

[0282] In the image forming apparatus 100 shown in Figure 4, an intermediate transfer method is adopted in which toner images formed on photosensitive bodies 111Y, 111M, 111C, and 111Bk are transferred to intermediate transfer body 131 by primary transfer rollers (primary transfer means) 133Y, 133M, 133C, and 133Bk, and each toner image transferred to intermediate transfer body 131 is transferred to transfer material P by secondary transfer roller (secondary transfer means) 217, but a direct transfer method may also be adopted in which toner images formed on the photosensitive bodies are transferred directly to transfer material P by transfer means.

[0283] The image forming system of the present invention uses toner particles containing a lubricant as an external additive, which can supply the lubricant to the cleaning means, but may also be provided with a separate lubricant supply means (not shown) such as a lubricant supply roller. [Example]

[0284] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these. In the examples, the terms "parts" and "%" are used, but unless otherwise specified, they represent "parts by mass" or "% by mass."

[0285] <Preparation of photoreceptor> The photoreceptor was prepared in the following manner.

[0286] (Conductive support) The surface of a cylindrical aluminum support having a diameter of 30 mm was machined to prepare a conductive support having a surface roughness Rz=1.5 (μm).

[0287] (middle class) The following materials were mixed and dispersed batchwise using a sand mill for 10 hours. After leaving to stand overnight, the mixture was filtered (using a Rigimesh 5 μm filter manufactured by Nippon Pall Corporation) to prepare an intermediate layer coating solution.

[0288] Polyamide resin CM8000 (manufactured by Toray Industries, Inc.) 1 part by mass Titanium oxide SMT500SAS (manufactured by Teika Co., Ltd.) 3 parts by weight Methanol 20 parts by mass

[0289] This intermediate layer coating solution was applied onto the conductive support by dip coating to form an intermediate layer having a dry thickness of 2 μm.

[0290] (charge generation layer) The following materials were mixed and dispersed for 10 hours using a sand mill to prepare a charge generating layer coating solution. The titanyl phthalocyanine pigment shown below has a maximum diffraction peak at at least 27.3° in Cu-Kα characteristic X-ray diffraction spectroscopy. The polyvinyl butyral resin used was #6000-C manufactured by Denki Kagaku Kogyo Co., Ltd.

[0291] Charge generating material: titanyl phthalocyanine pigment 20 parts by mass Polyvinyl butyral resin 10 parts by mass t-Butyl acetate 700 parts by mass 4-Methoxy-4-methyl-2-pentanone 300 parts by mass

[0292] This charge generating layer coating liquid was applied onto the intermediate layer by dip coating to form a charge generating layer having a dry thickness of 0.3 μm.

[0293] (charge transport layer) The following materials were mixed to prepare a charge transport layer coating solution. The following polycarbonate resin F (Iupizeta (registered trademark) FPC-6535A, manufactured by Mitsubishi Gas Chemical Company, Inc.) is a copolymer of bisphenol Z and a dihydroxy compound, and has a viscosity average molecular weight of 33,000. The antioxidant used was Irganox 1010 manufactured by BASF Japan Ltd.

[0294] Polycarbonate resin F 100 parts by mass Charge transport material (CTM-47) 50 parts by mass Antioxidant 2 parts by mass Tetrahydrofuran 540 parts by mass Toluene 135 parts by mass Silicone oil (KF-54: manufactured by Shin-Etsu Chemical Co., Ltd.) 0.3 parts by mass

[0295] [ka]

[0296] This charge transport layer coating liquid was applied onto the charge generation layer by dip coating to form a charge transport layer having a dry thickness of 20 μm.

[0297] (Surface protective layer) The following materials were mixed to prepare a mixture for surface modification of metal oxide particles. The tin oxide particles were manufactured by CIK Nanotech Co., Ltd. and had a number average primary particle size of 20 nm and a volume resistivity of 1.05 × 10 5 The surface modifier used was the following compound S-15, which has a radical polymerizable functional group.

[0298] Compound S-15: CH2=C(CH3)COO(CH2)3Si(OCH3)3

[0299] Metal oxide particles (tin oxide particles) 100 parts by mass Surface modifier (compound S-15) 30 parts by mass Toluene / isopropyl alcohol = 1 / 1 (mass ratio) 300 parts by mass

[0300] The prepared mixture was placed in a sand mill together with zirconia beads and stirred at approximately 40°C and 1500 rpm. The treated mixture was then removed and placed in a Henschel mixer and stirred at 1500 rpm for 15 minutes. The mixture was then dried at 120°C for 3 hours to complete the surface modification of the tin oxide particles with the compound having a radically polymerizable functional group, yielding surface-modified tin oxide particles.

[0301] By detecting the Si peak using an X-ray fluorescence analyzer "XRF-1700 (Shimadzu Corporation)," it was confirmed that the surfaces of the tin oxide particles were coated with compound S-15.

[0302] Next, the following materials were mixed and stirred to be thoroughly dissolved and dispersed to prepare a surface protective layer coating liquid.

[0303] Surface-modified tin oxide particles 50 parts Polymerizable compound (compound Mc-1) 100 parts Charge transport material (compound CTM-13) 15 parts Polymerization initiator (polymerization initiator 3-2) 10 parts Chain transfer agent (2-mercaptobenzoxazole) 10 parts 2-butanol 320 parts 80 parts tetrahydrofuran

[0304] [ka]

[0305] [ka]

[0306] [ka]

[0307] The surface protective layer coating solution was applied onto the charge transport layer using a circular slide hopper coater, and then irradiated with ultraviolet light using a metal halide lamp for 1 minute to form a surface protective layer with a dry thickness of 3.0 μm.

[0308] A photoreceptor was prepared according to the above procedure.

[0309] <Preparation of toner particles> Toner particles 1 were prepared by the following procedure.

[0310] (Preparation of dispersion of resin particles for core part) A surfactant solution prepared by dissolving 4 parts by mass of sodium polyoxyethylene-2-dodecyl ether sulfate in 3,040 parts by mass of ion-exchanged water was placed in a reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device, and the internal temperature was raised to 80°C while stirring at a stirring speed of 230 rpm under a nitrogen stream.

[0311] To this surfactant solution, a polymerization initiator solution prepared by dissolving 10 parts by mass of a polymerization initiator (potassium persulfate: KPS) in 400 parts by mass of ion-exchanged water was added, and after the temperature was raised to 75°C, a monomer mixture liquid consisting of 532 parts by mass of styrene, 200 parts by mass of n-butyl acrylate, 68 parts by mass of methacrylic acid, and 16.4 parts by mass of n-octyl mercaptan was added dropwise over 1 hour.

[0312] This system was heated and stirred at 75°C for 2 hours to carry out polymerization (first-stage polymerization), thereby preparing a dispersion of resin fine particles [A]. The weight-average molecular weight (Mw) of the resin fine particles [A] prepared in the first-stage polymerization was 16,500.

[0313] The weight-average molecular weight (Mw) was measured using an "HLC-8220" (manufactured by Tosoh Corporation) and a "TSKguard column + TSKgel Super HZM-M triple column" (manufactured by Tosoh Corporation). While maintaining the column temperature at 40°C, tetrahydrofuran (THF) was used as the carrier solvent, flowing at a flow rate of 0.2 mL / min. The sample to be measured was dissolved in tetrahydrofuran to a concentration of 1 mg / mL under dissolution conditions of 5 minutes using an ultrasonic disperser at room temperature. The sample was then filtered through a membrane filter with a pore size of 0.2 μm to obtain a sample solution. 10 μl of this sample solution was injected into the instrument together with the carrier solvent and detected using a refractive index detector (RI detector). The molecular weight distribution of the sample was calculated using a calibration curve measured using monodisperse polystyrene standard particles. The standard polystyrene sample used for the calibration curve measurement was a 6×10 6 polystyrene standard manufactured by Pressure Chemical Co. 2 , 2.1×10 3 , 4×10 3 , 1.75×10 4 , 5.1×10 4 , 1.1×10 5 , 3.9 × 10 6 , 8.6×10 5 , 2 × 10 6 , 4.48×10 6 At least 10 standard polystyrene samples were measured using a refractive index detector to create a calibration curve.

[0314] In a flask equipped with a stirrer, 93.8 parts by mass of paraffin wax "HNP-57" (manufactured by Nippon Seiro Co., Ltd.) was added as a release agent to a monomer mixture consisting of 101.1 parts by mass of styrene, 62.2 parts by mass of n-butyl acrylate, 12.3 parts by mass of methacrylic acid, and 1.75 parts by mass of n-octyl mercaptan, and the mixture was heated to 90°C to dissolve.

[0315] Meanwhile, a surfactant solution prepared by dissolving 3 parts by mass of sodium polyoxyethylene-2-dodecyl ether sulfate in 1,560 parts by mass of ion-exchanged water was heated to 98°C, and 32.8 parts by mass (solids equivalent) of the dispersion of the resin microparticles [A] described above was added to this surfactant solution. The monomer solution containing the paraffin wax was mixed and dispersed for 8 hours using a mechanical disperser "Clearmix" (manufactured by M Technique Co., Ltd.) with a circulation path, to prepare a dispersion containing emulsified particles with a dispersed particle size of 340 nm.

[0316] Next, a polymerization initiator solution prepared by dissolving 6 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water was added to this emulsion particle dispersion. This system was heated and stirred at 98°C for 12 hours to carry out polymerization (second-stage polymerization), thereby preparing a dispersion of resin microparticles [B]. The weight-average molecular weight (Mw) of the resin microparticles [B] prepared in the second-stage polymerization was 23,000.

[0317] A polymerization initiator solution prepared by dissolving 5.45 parts by mass of potassium persulfate in 220 parts by mass of ion-exchanged water was added to the above resin microparticles [B], and a monomer mixture consisting of 293.8 parts by mass of styrene, 154.1 parts by mass of n-butyl acrylate, and 7.08 parts by mass of n-octyl mercaptan was added dropwise over one hour at a temperature of 80°C.

[0318] After the dropwise addition was completed, polymerization (third-stage polymerization) was carried out by heating and stirring for 2 hours, and then the mixture was cooled to 28°C to obtain a dispersion of core resin particles. The core resin particles had a weight-average molecular weight (Mw) of 26,800. The core resin particles also had a volume-average particle size of 125 nm. The core resin particles also had a glass transition temperature (Tg) of 30.5°C.

[0319] (Preparation of dispersion of resin particles for shell layer) The dispersion of the resin particles for the shell layer was prepared by carrying out the polymerization reaction and post-reaction treatment in the same manner as in the first-stage polymerization for preparing the dispersion of the resin particles for the core portion, except that the monomer mixture was changed to 548 parts by mass of styrene, 156 parts by mass of 2-ethylhexyl acrylate, 96 parts by mass of methacrylic acid, and 16.5 parts by mass of n-octyl mercaptan. The glass transition temperature (Tg) of the resin particles for the shell layer was 49.8°C.

[0320] (Preparation of Colorant Fine Particle Dispersion) 90 parts by mass of sodium dodecyl sulfate was added to 1,600 parts by mass of ion-exchanged water, and while stirring this solution, 420 parts by mass of carbon black "Regal 330R" (manufactured by Cabot Corporation) was gradually added. Next, a dispersion process was carried out using a stirring device "Clearmix" (manufactured by M Technique Co., Ltd.), thereby preparing a colorant particle dispersion liquid in which colorant particles were dispersed.

[0321] The particle size of the colorant particles in this colorant particle dispersion was measured using an electrophoretic light scattering photometer "ELS-800" (manufactured by Otsuka Electronics Co., Ltd.) and was found to be 110 nm.

[0322] (Core formation) 420 parts by mass (solid content equivalent) of a dispersion of resin microparticles for the core part, 900 parts by mass of ion-exchanged water, and 100 parts by mass of a dispersion of colorant microparticles were placed in a reaction vessel equipped with a temperature sensor, a cooling pipe, a nitrogen introducing device, and a stirring device, and stirred.

[0323] The temperature inside the reaction vessel was adjusted to 30°C, and then a 5 mol / L aqueous solution of sodium hydroxide was added to the solution to adjust the pH to 8-11.

[0324] Next, an aqueous solution of 60 parts by mass of magnesium chloride hexahydrate dissolved in 60 parts by mass of ion-exchanged water was added at 30°C over 10 minutes with stirring. After leaving the mixture for 3 minutes, the temperature was raised to 80°C (the core formation temperature) over 80 minutes.

[0325] In this state, the particle size was measured using a flow particle image analyzer "FPIA2100" (manufactured by Sysmex Corporation), and when the volume-based average particle size of the particles reached 5.8 μm, an aqueous solution of 40.2 parts by mass of sodium chloride dissolved in 1,000 parts by mass of ion-exchanged water was added to stop the particle size growth.Furthermore, as a maturation treatment, the liquid was heated and stirred at a temperature of 80°C (core maturation temperature) for 1 hour to continue fusion and form a core.

[0326] The circularity of the core was measured using a flow particle image analyzer "FPIA2100" (manufactured by Sysmex Corporation) and was found to be 0.930.

[0327] In addition, the core portion was observed at 10,000x magnification by scanning transmission electron microscopy using a field emission scanning electron microscope "JSM-7401F" (manufactured by JEOL Ltd.), and it was confirmed that the colorant had dissolved in the binder resin and that no dispersed colorant particles remained.

[0328] (Shell layer formation) Next, 46.8 parts by mass (solids equivalent) of a dispersion of resin particles for the shell layer was added at 65°C. Furthermore, an aqueous solution of 2 parts by mass of magnesium chloride hexahydrate dissolved in 60 parts by mass of ion-exchanged water was added over 10 minutes. The mixture was then heated to 80°C (shell formation temperature) and stirred for 1 hour, causing the particles of resin particles for the shell layer to fuse to the surface of the core.

[0329] The mixture was then aged at 80°C (shell aging temperature) until it reached a predetermined circularity, forming a shell layer. An aqueous solution of 40.2 parts by mass of sodium chloride dissolved in 1,000 parts by mass of ion-exchanged water was added, and the mixture was cooled to 30°C at a rate of 8°C / min. The resulting fused particles were filtered and repeatedly washed with ion-exchanged water at 45°C. The particles were then dried with hot air at 40°C.

[0330] By the above procedure, toner base particles having a shell layer on the surface of the core were obtained. The toner base particles had a volume-based average particle size of 5.9 μm, a glass transition temperature (Tg) of 31° C., and an average circularity of 0.960.

[0331] (Addition of external additives) External additives were added to the toner base particles prepared as described above using the following procedure. Two types of fatty acid metal salt particles were added as lubricants. Hereinafter, of the two types of lubricants added in the production of each toner, the lubricant with the smaller volume-based average particle size will be referred to as "lubricant (1)," and the lubricant with the larger volume-based average particle size will be referred to as "lubricant (2)."

[0332] To 100 parts by mass of the dried toner base particles, 0.25 parts by mass of zinc stearate particles (volume-based average particle size 1.0 μm, manufactured by NOF Corporation) were added as lubricant (1), and the mixture was mixed using a Henschel mixer "FM10B" (manufactured by Mitsui Miike Chemical Engineering Co., Ltd.) at a stirring blade peripheral speed of 15 m / s and a processing temperature of 30°C for 3 minutes.

[0333] Next, 0.75 parts by mass of small-diameter silica particles ("RX-200" fumed silica, HMDS-treated, number-average particle size 12 nm; manufactured by Nippon Aerosil Co., Ltd.), 1.50 parts by mass of spherical silica particles ("X-24 9600" sol-gel silica, HMDS-treated, number-average particle size 80 nm; manufactured by Shin-Etsu Chemical Co., Ltd.), 0.1 parts by mass of zinc stearate particles (volume-based average particle size 15.0 μm, manufactured by NOF Corporation) as lubricant (2), and 0.5 parts by mass of calcium titanate particles ("TC110" number-average primary particle size 300 nm, silicone oil-treated, manufactured by Titan Kogyo Co., Ltd.) as metal oxide particles with high polishing effect were added, and the mixture was mixed using a Henschel mixer "FM10B" (manufactured by Mitsui Miike Chemical Engineering Co., Ltd.) at a stirring blade peripheral speed of 40 m / s and a processing temperature of 30°C for 15 minutes.

[0334] Thereafter, coarse particles were removed using a sieve with 90 μm openings, thereby preparing toner particles 1.

[0335] Toner particles 2 to 9 were produced by changing the added lubricant (1) and lubricant (2) in the production of toner particles 1 to fatty acid metal salt particles (both manufactured by NOF Corporation) shown in Table I. Note that in toner particles 2 and 3, only one type of fatty acid metal salt particle was added.

[0336] In Table I, "Amount added [parts by mass]" is the amount added per 100 parts by mass of toner base particles. Also, "ZnSt," "MgSt," and "CaSt" refer to "zinc stearate," "magnesium stearate," and "calcium stearate," respectively.

[0337] [Table 1]

[0338] The volume-based particle size distribution of the lubricant in toner particles 1 to 9 was measured according to the following procedure.

[0339] 5 g of toner particles and 50 mL of a 0.7% aqueous solution of sodium dodecylbenzenesulfonate were placed in a 100 mL beaker and dispersed by stirring at 300 rpm for 5 minutes using a magnetic stirrer "Model MS500D" (manufactured by Yamato Scientific).

[0340] After the dispersion, ultrasonic vibration was applied to the toner dispersion for 10 minutes using an ultrasonic homogenizer "US-1200T" (manufactured by Nippon Seiki Seisakusho) at a frequency of 20 kHz, output setting of 3, and tuning setting of 6.

[0341] The toner dispersion was separated by centrifuging in a Model H-900 centrifuge (manufactured by Kokusan) under the following conditions. Rotor: PC-400 (radius 18.1 cm) Rotation speed: 1200 rpm (292 G) Time: 10 minutes

[0342] After centrifugation, 40 mL of the supernatant was collected using a pipette so as not to include the settled toner base particles.

[0343] The volumetric particle size of the particles contained in the collected supernatant was measured using a flow particle image analyzer "FPIA-2100" (manufactured by Sysmex Corporation) in the measurement range of 0.6 to 400 μm, thereby determining the volumetric particle size distribution of the lubricant.

[0344] The volumetric particle size distribution of the lubricant in toner particles 1, and 4 to 9 had two peaks, one on the small particle side and one on the large particle side. The volumetric average particle size of the lubricant having a peak on the small particle side (lubricant on the small particle side) and the volumetric average particle size of the lubricant having a peak on the large particle side (lubricant on the large particle side) are shown in Table II.

[0345] The volume-based particle size distribution of the lubricant in toner particles 2 and 3 did not have two peaks on the small particle size side and the large particle size side.

[0346] <How to make a brush roller> A pile fabric having the following pile woven into a base fabric was wound around the outer layer of an aluminum shaft having an outer diameter of 13 mm and a length of 330 mm and fixed with an adhesive to prepare a brush roller 1.

[0347] (pile) Material: Polyester Shape: cut pile Young's modulus: 45cN / dtex Pile bundle fineness: 150 dtex Pile density: 80KF / inch 2 Pile length: 3mm

[0348] Brush rollers 2 to 17 were produced by changing the pile woven into the pile fabric used in producing brush roller 1 as shown in Table II.

[0349] <Image forming system> The photoreceptor prepared above was installed in a commercially available full-color multifunction printer "bizhub C650i" (manufactured by Konica Minolta, Inc.). The printer was also modified to allow a brush roller to be installed, and toner particles 1 to 9 and brush rollers 1 to 17 were used in the combinations shown in Table II to form image forming systems 1 to 26. The brush roller was located upstream of the cleaning blade in the rotation direction of the photoreceptor.

[0350] The brush roller rotated in the same direction as the photoreceptor (the surface moved in the same direction) at a rotation speed of 600 rpm. The rotation speed of the brush roller was controlled by applying a voltage to an external DC drive motor.

[0351] <Evaluation of the difference in the amount of lubricant attached to the photoreceptor> In a low-temperature, low-humidity environment (temperature 10°C, humidity 10% RH), 1,000 pattern images each having a printed area and a non-printed area on the left and right halves relative to the rotation direction of the photoreceptor were continuously printed. After that, 5 mm square pieces of the surface protection layer in the area corresponding to the printed area of ​​the pattern image (toner application area) and the area corresponding to the non-printed area of ​​the pattern image (toner non-application area) were cut out from the photoreceptor, and these were used as measurement samples.

[0352] The abundance ratio (atom %) of metals derived from fatty acid metal salts that make up the lubricant was measured by X-ray photoelectron spectroscopy (ESCA: Electron Spectroscopy for Chemical Analysis), and this was used as a proxy for the amount of lubricant adhered.

[0353] The element ratios contained in the measurement samples were quantitatively analyzed using an X-ray photoelectron spectrometer "K-Alpha" (manufactured by Thermo Fisher Scientific) under the following measurement conditions.

[0354] (Measurement conditions) X-ray: Al monochromatic source Acceleration: 12kV, 6mA Resolution: 50eV Beam system: 400 μm Step size: 0.1 eV

[0355] The elements to be quantitatively analyzed were all elements that could be considered to be present on the surface of the measurement sample, such as elements contained in the constituent components of the surface protective layer and elements contained in the constituent components of the toner particles.

[0356] The relative sensitivity factor was used to calculate the abundance ratio (atom %) of metals derived from the fatty acid metal salts that make up the lubricant from the peak areas of each quantitatively analyzed element. The difference between the value measured from the measurement sample of the surface protective layer in the toner-applied area and the value measured from the measurement sample of the surface protective layer in the non-toner-applied area was used as the evaluation result. The evaluation results are shown in Table II.

[0357] <Evaluation of the suppression effect of image memory> In a low-temperature, low-humidity environment (temperature 10°C, humidity 10% RH), 1,000 pattern images with printed and non-printed areas on the left and right halves of the photoreceptor rotation direction were printed consecutively, followed by one full-face halftone image.

[0358] The reflection density (D1) of the printed area of ​​the pattern image and the reflection density (D0) of the non-printed area of ​​the pattern image were measured using a Macbeth RD920 (manufactured by Macbeth).

[0359] The reflection density difference ΔD (D1-D0) was calculated, and the effect of suppressing image memory was evaluated according to the following criteria. The evaluation results are shown in Table II. A rating of ◯ or above was judged as passing. ◎: Reflection density difference ΔD is less than 0.1 ○: Reflection density difference ΔD is 0.1 or more and less than 0.3 ×: Reflection density difference ΔD is 0.3 or more

[0360] <Abrasion resistance evaluation> A character chart equivalent to a printing rate of 5% was printed continuously on both sides for 300,000 sheets in an environment of 23°C temperature and 50% RH. After that, the thickness of the surface protection layer of the photoreceptor was measured using an eddy current film thickness measuring device "Fisherscope MMS PC" (manufactured by Fischer Instruments Co., Ltd.).

[0361] The abrasion loss of the surface protective layer was calculated from the measured thickness, and the abrasion resistance was evaluated according to the following criteria. The evaluation results are shown in Table II. A rating of ◯ or higher was judged to be acceptable. ◎: Wear amount is less than 0.2 μm ○: Abrasion amount is 0.2 μm or more and less than 0.4 μm ×: Abrasion amount is 0.4 μm or more

[0362] [Table 2]

[0363] From the above examples, it can be seen that the electrophotographic image forming system of the present invention is suitable for long-term use of the electrophotographic photosensitive member. It can be seen that both improved wear resistance and suppression of image memory are achieved. In Table II, "the present invention" in the remarks column for image forming system No. 17 should be read as "reference example." [Explanation of symbols]

[0364] 100 Image forming device 110Y, 110M, 110C, 110Bk Image forming unit 111Y, 111M, 111C, 111Bk, 111 Electrophotographic Photoreceptor 113Y, 113M, 113C, 113Bk Charging means 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) 120 Brush Roller 121 Cleaning blade 122 Support member

Claims

1. 1. An electrophotographic image forming system for forming an image using a toner for developing an electrostatic charge image, the toner comprising toner particles, The electrophotographic image forming apparatus comprises an electrophotographic photosensitive member, a charging means, an exposure means, a developing means, a transfer means, and a cleaning means, the toner particles contain toner base particles and a lubricant as an external additive, the volume-based particle size distribution of the lubricant has two peaks on the small particle size side and the large particle size side, the volume-based average particle size of the lubricant having the peak on the small particle size side is 3.0 μm or less, and the volume-based average particle size of the lubricant having the peak on the large particle size side is larger than the volume-based average particle size of the toner base particles, the cleaning means comprises a brush roller having a plurality of pile bundles, and a cleaning blade provided downstream of the brush roller in the rotation direction of the electrophotographic photosensitive member, The pile bundle fineness [dtex] of the brush roller is X, and the pile density [KF / inch ２ ] is Y, the following formulas (1) and (2) are satisfied: The Young's modulus of the pile constituting the pile bundle is within the range of 25 to 70 cN / dtex. Electrophotographic image forming system. Formula (1): 100≦Y≦250 Formula (2): 0.7≦X / Y≦2.2

2. The electrophotographic photoreceptor has a surface protective layer containing a cured resin.

2. An electrophotographic imaging system according to claim 1.

3. The lubricant is a particle whose main component is zinc stearate.

3. An electrophotographic image forming system according to claim 1 or 2.

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