Electrophotographic image forming system and electrophotographic image forming method

Abstract

To provide an image formation system and the like that stabilize behavior of a cleaning blade, and prevent toner slipping even in long-term durable printing or occurrence of adhesion of foreign matters onto a photoreceptor.SOLUTION: In an electrophotographic image formation system of the present invention, cleaning means is the means that makes a tip ridge part of the cleaning blade having an edge angle formed into an obtuse angle shape abut against a photoreceptor to perform cleaning, and has lubricant supply means that adds lubricant to the toner to supply the toner to the photoreceptor. The photoreceptor has at least a photosensitive layer and protection layer on a conductivity support body in this order, and the protection layer is formed of a curing object of a composition including a charge transportable compound having a polymerizable functional group and metal oxide particles. An irregularity average interval Rsm of a surface of the protection layer falls within a range of 5 to 20 μm, and at least a number average primary particle diameter includes a metal oxide particle falling within a range of 150 to 550 nm within a range of 1 to 30 vol.% in the protection layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an electrophotographic image forming system and an electrophotographic image forming method. In particular, it relates to an image forming system that can stabilize the behavior of a cleaning blade and does not cause toner leakage or foreign matter adhesion to a photoreceptor even in long-term durable printing.

Background Art

[0002] In an organic photoreceptor that constitutes an image forming apparatus such as an electrophotographic copier or printer, long life and image quality stability of the formed image are required. In the photoreceptor, the life of the photoreceptor is determined by the wear of the photoreceptor surface. In addition, image quality deterioration is caused by minute scratches and wear unevenness formed by the wear of the photoreceptor surface.

[0003] In recent years, photoreceptors having excellent wear resistance, scratch resistance, and environmental stability and being designed for long life have been developed. For example, Patent Document 1 discloses an organic photoreceptor in which an organic photosensitive layer is laminated on a conductive support, and a protective layer made of a cured resin is further formed on the organic photosensitive layer. An organic photoreceptor having a protective layer made of a cured resin is excellent in wear resistance. However, since it is difficult to refresh the photoreceptor surface, there is a problem that foreign matter attached to the photoreceptor surface grows and is easily detected as noise on the image. In order to suppress the adhesion of foreign matter to the photoreceptor surface, means for supplying a lubricating component to the photoreceptor surface has been proposed. As a means for supplying the lubricating component, there is a method of supplying the lubricant by bringing a lubricant bar into contact with the photoreceptor. However, from the viewpoint of downsizing the apparatus, a method of adding a lubricant to the toner and supplying the lubricant from the toner to the photoreceptor may be adopted. Further, from the viewpoint of suppressing the surface wear of the photoreceptor, a method of using a cleaning blade having an obtuse edge angle and reducing the line pressure of the blade contact portion is disclosed (see Patent Document 2).

[0004] When supplying a lubricant from toner to a photoreceptor, a difference in the amount of lubricant on the surface of the photoreceptor occurs between the image area where toner is supplied and the non-image area where toner is not supplied. Since the protective layer made of a cured resin does not wear easily, it is easy to hold the lubricant on the surface, and the difference in the amount of lubricant between the image area and the non-image area becomes more prominent. When there is a significant difference in the amount of lubricant in the axial direction on the surface of the photoreceptor, the coefficient of friction is different between the part with a large amount of lubricant applied and the part with a small amount of lubricant applied. Therefore, a difference occurs in the amount of drawing-in of the cleaning blade that abuts on the photoreceptor in the axial direction, and the blade behavior becomes unstable. As a result, toner may slip through at a specific part, or a large amount of slipped-through toner or external additives of the toner may adhere to the surface of the photoreceptor, resulting in image noise. In particular, when the edge angle of the cleaning blade is an obtuse angle shape, it is more likely to be affected by the surface state of the photoreceptor than in the case of a right angle shape, so this has often been a problem.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] The present invention has been made in view of the above problems and situations, and the problems to be solved are as follows. In an image forming system that uses a photoreceptor having a protective layer made of a cured resin, uses a cleaning blade with an obtuse angle shape, and supplies a lubricant from toner, the behavior of the cleaning blade can be stabilized. And an electrophotographic image forming system and an image forming method that do not cause toner slippage or foreign matter adhesion on the photoreceptor even in long-term durable printing are provided.

Means for Solving the Problems

[0007] In order to solve the above problems, the inventors, in the process of investigating the causes of the above problems, controlled the average spacing Rsm of the surface irregularities of the protective layer of the photoreceptor, and the particle size and content of the metal oxide particles contained in the protective layer. As a result, they found that the behavior of the cleaning blade is stabilized and toner leakage and adhesion of foreign matter to the photoreceptor do not occur even during long-term durable printing, leading to the present invention. In other words, the above-mentioned problems according to the present invention are solved by the following means.

[0008] 1. An electrophotographic image forming system having at least a photoreceptor, charging means, exposure means, developing means, transfer means and cleaning means, The cleaning means is a means of cleaning the photoreceptor by bringing the tip edge of a cleaning blade with an obtuse edge angle into contact with the photoreceptor, The toner has a lubricant supply means for adding a lubricant and supplying it onto the photoreceptor, The photoreceptor has at least a photosensitive layer and a protective layer on a conductive support in this order, and the protective layer is formed of a cured product of a composition containing a charge-transporting compound having polymerizable functional groups and metal oxide particles. The average spacing Rsm of the surface irregularities of the protective layer is within the range of 5 to 20 μm, and An electrophotographic image forming system characterized by containing metal oxide particles having a number average primary particle size in the range of 150 to 550 nm in the protective layer in an amount of 1 to 30 volume percent.

[0010] 2 The electrophotographic image forming system according to the first claim, characterized in that the toner contains alumina particles.

[0011] 3 The charge transport compound having the polymerizable functional group has a structure represented by the following general formula (1). The electrophotographic image forming system according to feature 1. [ka] In general formula (1), Ar 1 and Ar 2 each independently represent a structure represented by general formula (2). Ar 3 represents a structure represented by general formula (2) or general formula (3). D each independently represents -(-(CH2) d -(O-(CH2) f -) e -O-CO-C(CH3)=CH2) or -(-(CH2) d -(O-(CH2) f -) e -O-CO-CH=CH2). d and f each independently represent an integer of 0 or more and 5 or less. e represents an integer of 0 or 1. c1 to c3 each independently represent an integer of 0 to 2. Ar 3 When represents a structure represented by general formula (2), the total number of D in the compound is 1 or 2. Ar 3 When represents a structure represented by general formula (3), the total number of D in the compound is 1.)

Chemical formula

[0012] 4 . The electrophotographic image forming system according to claim 1, wherein a brush that contacts the photoreceptor is provided after the transfer means and before the cleaning means.

[0013] 5 An electrophotographic image forming method using a photoreceptor, comprising at least a charging step, an exposure step, a development step, a transfer step, and a cleaning step, The cleaning step is a step of cleaning the photoreceptor by bringing the tip edge of a cleaning blade, which has an obtuse edge angle, into contact with the photoreceptor. The means for supplying the lubricant onto the photoreceptor is a method of supplying toner with a lubricant added to it. The photoreceptor has at least a photosensitive layer and a protective layer on a conductive support in this order, and the protective layer is formed of a cured product of a composition containing a charge-transporting compound having polymerizable functional groups and metal oxide particles. The average spacing Rsm of the surface irregularities of the protective layer is within the range of 5 to 20 μm, and The protective layer contains metal oxide particles with a number average primary particle size in the range of 150 to 550 nm in an amount of 1 to 30 volume%, Furthermore, the protective layer contains metal oxide particles with a number-average primary particle size in the range of 25 to 75 nm in an amount of 5 to 15 volume%. A method for forming an electrophotographic image characterized by [a specific feature]. [Effects of the Invention]

[0014] The above means of the present invention makes it possible to stabilize the behavior of the cleaning blade even in an image forming system that uses a cleaning blade with an obtuse edge angle and supplies lubricant from toner, in a photoreceptor having a protective layer of cured resin. Furthermore, it is possible to provide an electrophotographic image forming system and image forming method that does not cause toner leakage or adhesion of foreign matter on the photoreceptor even during long-term durable printing. Although the mechanism of action or mechanism of the present invention is not yet clear, it is speculated as follows. When the surface of the photoreceptor is smooth, differences in the amount of lubricant applied are directly transmitted to the cleaning blade, easily resulting in differences in the amount the blade is retracted. Simply creating irregularities on the surface of the photoreceptor is insufficient to stabilize the blade's behavior. Therefore, in this invention, the average spacing Rsm of the surface irregularities of the protective layer of the photoreceptor is set within the aforementioned range, and metal oxide particles with a number-average primary particle size of 150 to 550 nm are included in the protective layer within a specific range. With this configuration, the long-period (approximately 5 μm or more) undulations of the resin in the photoreceptor and the irregularities (on the order of several hundred nm) formed by the large-particle filler that is harder than the resin are superimposed. As a result, the disorder of the photoreceptor surface is dramatically increased, and it is presumed that a remarkable blade behavior stabilization effect can be obtained. [Brief explanation of the drawing]

[0015] [Figure 1] A conceptual diagram showing the relationship between the cleaning blade and the electrophotographic photoreceptor according to the present invention, viewed from the side. [Figure 2] Explanatory cross-sectional view showing an example of the configuration of the image forming apparatus according to the present invention. [Figure 3] Explanatory cross-sectional view showing an example of the configuration of the main parts of an image forming apparatus. [Figure 4] A schematic diagram showing an example of the configuration of the charging means of the image forming apparatus according to the present invention. [Modes for carrying out the invention]

[0016] The electrophotographic image forming system of the present invention is an electrophotographic image forming system having at least a photoreceptor, a charging means, an exposure means, a developing means, a transfer means, and a cleaning means, wherein the cleaning means is a means for cleaning by bringing the tip edge of a cleaning blade having an obtuse edge angle into contact with the photoreceptor, and also has a lubricant supply means for supplying toner with a lubricant added onto the photoreceptor, wherein the photoreceptor has at least a photosensitive layer and a protective layer in that order on a conductive support, the protective layer is formed of a cured product of a composition containing a charge transport compound having a polymerizable functional group and metal oxide particles, the average spacing Rsm of the surface irregularities of the protective layer is in the range of 5 to 20 μm, and the protective layer contains metal oxide particles with at least a number mean primary particle size in the range of 150 to 550 nm in the range of 1 to 30 volume%. This feature is a technical feature common to or corresponding to each of the embodiments described below.

[0017] In embodiments of the present invention, it is preferable to further include metal oxide particles having a number-average primary particle size in the range of 25 to 75 nm in the protective layer in an amount of 5 to 15 volume percent. Including metal oxide particles with a particle size of 25 to 75 nm is preferable because it further improves the disorder of the protective layer surface.

[0018] Furthermore, it is preferable that the toner contains, for example, alumina particles as an external additive. The external additive that separates from the toner particles accumulates between the edge of the cleaning blade and the photoreceptor, polishing the photoreceptor. Here, the inclusion of high-hardness alumina particles in the external additive allows for uniform abrasion of the photoreceptor resin and metal oxide particles, which have different hardness levels. As a result, stable cleaning performance can be achieved throughout the entire process.

[0019] Furthermore, it is preferable that the charge-transporting compound having the polymerizable functional group has a structure represented by the general formula (1). The presence of a structure containing particularly long chains, such as alkyl chains or alkylene oxide chains, as represented by the general formula (1), improves the dispersibility of metal oxide particles. As a result, the effects of the present invention are more easily realized.

[0020] Furthermore, it is preferable that a brush that contacts the photoreceptor is provided after the transfer means and before the cleaning means. By providing a brush that contacts the photoreceptor before the cleaning means, differences in the amount of lubricant applied are equalized. At the same time, the toner containing the alumina particles held by the brush uniformly abrades the surface of the photoreceptor, making the effects of the invention more pronounced.

[0021] The present invention relates to an electrophotographic image forming method that uses a photoreceptor and comprises at least a charging step, an exposure step, a developing step, a transfer step, and a cleaning step, wherein the cleaning step is a step of cleaning by bringing the tip edge of a cleaning blade having an obtuse edge angle into contact with the photoreceptor, the means for supplying a lubricant to the photoreceptor is a method of supplying a lubricant by adding it to toner, the photoreceptor has at least a photosensitive layer and a protective layer in this order on a conductive support, the protective layer is formed of a cured product of a composition containing a charge-transporting compound having a polymerizable functional group and metal oxide particles, the average spacing Rsm of the surface irregularities of the protective layer is in the range of 5 to 20 μm, and the protective layer contains metal oxide particles in the range of 1 to 30 volume%, with at least a number-average primary particle size in the range of 150 to 550 nm. This allows for stable behavior of the cleaning blade even in an image forming system that uses a cleaning blade with an obtuse edge angle and supplies lubricant from toner, with a photoreceptor having a protective layer of cured resin. As a result, it is possible to provide an electrophotographic image forming method that prevents toner leakage and foreign matter adhesion to the photoreceptor even during long-term durable printing.

[0022] The present invention, its components, and embodiments for carrying out the present invention will be described below. In this application, "~" is used to mean that the numerical values ​​written before and after it are included as the lower limit and upper limit.

[0023] [Overview of the image forming system of the present invention] The image forming system of the present invention is an electrophotographic image forming system having at least a photoreceptor, a charging means, an exposure means, a developing means, a transfer means, and a cleaning means. The cleaning means involves cleaning the photoreceptor by bringing the tip edge of a cleaning blade, which has an obtuse edge angle, into contact with the photoreceptor. Furthermore, the image forming system of the present invention includes a lubricant supply means for supplying toner with a lubricant added to it onto the photoreceptor. The photoreceptor has at least a photosensitive layer and a protective layer on a conductive support in this order. The protective layer is formed of a cured product of a composition containing a charge-transporting compound having polymerizable functional groups and metal oxide particles. The average spacing Rsm of the surface irregularities of the protective layer is in the range of 5 to 20 μm. The protective layer also contains at least 1 to 30 volume percent of metal oxide particles with a number-average primary particle size in the range of 150 to 550 nm.

[0024] <Average unevenness interval Rsm> The average surface irregularity (Rsm) of the protective layer was measured in accordance with the JIS standard (JIS B0601:2013) under the following measurement conditions, by measuring the Rsm in the longitudinal direction of the photoreceptor. (Measurement conditions) Measuring device: Surfcom 1400D (manufactured by Tokyo Seimitsu Co., Ltd.) Measurement mode: Roughness measurement Measurement length: 20.0 mm Cutoff: 0.08mm (Gaussian) Measurement speed: 0.15mm / sec In this invention, the average value of a total of nine points is shown, measured at three points in the circumferential direction at three locations along the longitudinal direction of the photoreceptor (the center and 60 mm from both ends).

[0025] The average spacing Rsm of the unevenness is in the range of 5 to 20 μm, preferably in the range of 6 to 15 μm, and particularly preferably in the range of 7 to 12 μm.

[0026] Means for keeping the average spacing Rsm of the unevenness within the range include, for example, variations depending on the composition of the protective layer, but controllable by the formation conditions of the protective layer. To control the composition of the protective layer, for example, one can adjust the resin type or the content of metal oxide particles. Specifically, when controlling the Rsm by the formation conditions of the protective layer, increasing the Rsm can be achieved by reducing the amount of solvent relative to the resin composition or increasing the ratio of tetrahydrofuran to 2-butanol. This increases the viscosity of the coating solution and changes the film shrinkage rate of the protective layer. As a result, the surface properties of the protective layer can be controlled. On the other hand, decreasing the Rsm can be achieved by increasing the amount of solvent relative to the resin composition or decreasing the ratio of tetrahydrofuran to 2-butanol.

[0027] For example, it is preferable that the amount of solvent relative to the resin composition be in the range of 4 to 8 parts by mass. Furthermore, it is preferable that the amount of tetrahydrofuran relative to 2-butanol be in the range of 1.5 to 3 times.

[0028] Furthermore, the means of controlling Rsm are not limited to those described above. Other methods include changing the amount of polymerization initiator or the UV irradiation time during protective layer formation to alter the curing rate of the film. Additionally, the surface of the protective layer can be altered by post-processing using a device capable of polishing the photoreceptor surface.

[0029] <Number-average primary particle size of metal oxide particles> The protective layer contains metal oxide particles (also called "large-diameter metal oxide particles") with a number-average primary particle size in the range of 150 to 550 nm. Preferably, it is in the range of 250 to 350 nm. Furthermore, it is preferable that the protective layer contains, in addition to the large-diameter metal oxide particles, metal oxide particles (also called "small-diameter metal oxide particles") having a number-average primary particle size in the range of 25 to 75 nm. The addition ratio of metal oxide particles with a number-average primary particle size of 150 to 550 nm is within the range of 1 to 30 volume percent relative to 100 volume percent of the solid content of the coating liquid for forming the surface protective layer, as described later. In particular, it is preferable to have a ratio within the range of 15 to 25 volume percent. On the other hand, the addition ratio of metal oxide particles with a number-average primary particle size of 25 to 75 nm is preferably in the range of 5 to 15 volume percent relative to 100 volume percent of the solid content of the coating liquid for forming the surface protective layer.

[0030] (Method for measuring the particle size of metal oxide particles) The particle size (number-average primary particle size) of the above metal oxide particles is determined by taking 10,000x magnified photographs using a scanning electron microscope (manufactured by JEOL Ltd.). Then, 300 randomly selected particles are scanned, and the resulting images (excluding aggregated particles) are binarized using the automated image processing and analysis system "LUZEX AP (registered trademark) AP)" (manufactured by Nireco Corporation) software Ver. 1.32. The horizontal Ferret diameter is then calculated for each image. The average value of the horizontal Ferret diameter is calculated as the number-average primary particle size. Here, the horizontal Ferret diameter refers to the length of the side parallel to the x-axis of the circumscribing rectangle when the image of the metal oxide particles is binarized. For electron microscopy observation, the photosensitive layer and protective layer were cut from the conductive support at three locations along the longitudinal direction of the photoreceptor (the center and 60 mm from both ends), and the protective layer was observed. The average value of these three locations was then used as the particle size of the metal oxide particles.

[0031] [Electrophotographic photoconductor] The photoreceptor according to the present invention is an electrophotographic photoreceptor for use in an electrophotographic image forming apparatus. The photoreceptor has at least a photosensitive layer and a protective layer (also called a "surface protective layer") on a conductive support, in this order. The protective layer is formed from a cured product of a composition containing a charge-transporting compound having polymerizable functional groups and metal oxide particles. The photosensitive layer has both the function of absorbing light and generating electric charge, and the function of transporting electric charge.

[0032] The photosensitive layer may have a single-layer structure containing a charge-generating material and a charge-transporting material, provided that the protective layer is on the outermost surface. Alternatively, it may have a laminated structure consisting of a charge-generating layer containing a charge-generating material and a charge-transporting layer containing a charge-transporting material. Furthermore, an intermediate layer may be provided between the conductive support and the photosensitive layer as needed. The photosensitive layer is not particularly limited in its layer structure, and specific layer structures including the protective layer and intermediate layer include, for example, the following.

[0033] (i) A layer configuration in which a photosensitive layer and a protective layer, each consisting of a charge generation layer and a charge transport layer, are sequentially laminated on a conductive support. (ii) A layer configuration in which a single-layer photosensitive layer containing a charge transport material and a charge generating material and a protective layer are sequentially laminated on a conductive support. (iii) A layer configuration in which an intermediate layer, a photosensitive layer consisting of a charge generation layer and a charge transport layer, and a surface protective layer are sequentially laminated on a conductive support. (iv) A layer configuration in which an intermediate layer, a single-layer photosensitive layer containing a charge transport material and a charge generating material, and a protective layer are sequentially laminated on a conductive support.

[0034] The photoreceptor according to the present invention may have any of the above layer configurations (i) to (iv), and these Among these, the layer configuration described in (iii) above is particularly preferred.

[0035] Furthermore, the photoreceptor according to the present invention is an organic photoreceptor. An organic photoreceptor means an electrophotographic photoreceptor in which at least one of the charge generation function and charge transport function, which are indispensable for the structure of an electrophotographic photoreceptor, is expressed by an organic compound. This includes photoreceptors composed of known organic charge generation substances or organic charge transport substances, and photoreceptors in which the charge generation function and charge transport function are composed of a polymer complex.

[0036] <Protective layer> The protective layer according to the present invention contains a polymer of a charge-transporting compound (polymerizable compound) having at least a polymerizable functional group within its molecule. The polymerizable functional group may be at least one in the molecule, and the charge transporting compound may be a monofunctional polymerizable compound (also called a "monofunctional polymerizable monomer") or a polyfunctional polymerizable compound (also called a "polyfunctional polymerizable monomer"). Furthermore, the polyfunctional polymerizable compounds include polyfunctional polymerizable compounds that have hole transport properties and polyfunctional polymerizable compounds that do not have hole transport properties (i.e., do not possess hole transport properties). The monofunctional polymerizable compound is preferably hole transportable.

[0037] In this invention, "hole transportability" refers to having a hole transport ability that is higher than electron transport ability. In other words, it refers to a characteristic in which hole mobility is greater than electron mobility. An ionization potential (the energy required to remove electrons from a neutral molecule and ionize it) of 6.2 eV or less is preferable because it facilitates hole injection. In particular, an ionization potential within the range of 4.5 to 6.2 eV is preferable in terms of preventing oxidation of the compound. As for hole transport capacity, 1 × 10 -7 cm 2 It is preferable to have a drift mobility of / Vsec or greater.

[0038] The method for measuring hole or electron mobility is not particularly limited. Specific methods include, for example, the following: (1) Time of flight method (a method calculated from the measurement of the travel time of charges within an organic film) (2) Method for calculation from the voltage characteristics of the space charge limiting current (3) Method determined from peak frequencies measured by impedance spectroscopy

[0039] Examples of "polymerizable compounds with hole transport properties" include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and compounds having groups derived from these substances. Among these, triarylamine compounds and benzidine compounds are preferred, and these are specifically the compounds described later.

[0040] Furthermore, "polymerizable compounds that do not transport holes" include polymerizable compounds other than the polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and compounds having groups derived from these substances. Specifically, these are the compounds described later.

[0041] Therefore, the protective layer is a cured product of a coating solution containing at least one of the following: a polyfunctional polymerizable compound having hole transport properties, a polyfunctional polymerizable compound that does not have hole transport properties, or a monofunctional polymerizable compound having hole transport properties, and metal oxide particles. The aforementioned coating liquid is also referred to as a coating liquid for forming a surface protective layer. Furthermore, the coating solution preferably contains a photopolymerization initiator and may also contain known charge transport substances other than the hole transporting polyfunctional or monofunctional polymerizable compounds.

[0042] As the polyfunctional polymerizable compound having or not having hole-transporting properties, it is preferable to use monomers that have radical polymerizable functional groups and which polymerize (cure) with a radical polymerization initiator to constitute a binder resin for a photoreceptor. Examples of binder resins include polystyrene and polyacrylate. From the viewpoint of maintaining high durability, it is preferable to use a crosslinkable polymerizable compound as the polyfunctional polymerizable compound. Specifically, examples of crosslinkable polymerizable compounds include polymerizable compounds having two or more radical polymerizable functional groups.

[0043] The following will be explained in order: [1] polyfunctional or monofunctional polymerizable compounds having hole transport properties, [2] polyfunctional polymerizable compounds that do not have hole transport properties, [3] photopolymerization initiators, [4] metal oxide particles, and [5] other additives.

[0044] [1] Polyfunctional or monofunctional polymerizable compounds having hole transport properties The aforementioned polyfunctional or monofunctional polymerizable compound having hole-transporting properties (charge-transporting compound having polymerizable functional groups) has a structure represented by the following general formula (1).

[0045] [ka]

[0046] In general formula (1), Ar 1 and Ar 2 This shows a structure that can be independently represented by general formula (2). Ar 3 This represents a structure that can be expressed by the following general formula (2) or general formula (3). D is independently, -(-(CH2) d -(O-(CH2) f -) e -O-CO-C(CH3)=CH2) or -(-(CH2) d -(O-(CH2) f -) e The structure is represented by -O-CO-CH=CH2). d and f are independent integers between 0 and 5 (inclusive). e is an integer of 0 or 1. c1 to c3 independently represent integers between 0 and 2. Ar 3 However, when the structure is represented by general formula (2), the total number of D atoms in the compound is 1 or 2. 3 However, when the structure is represented by general formula (3), the total number of D atoms in the compound is 1.

[0047] [ka]

[0048] In general formulas (2) and (3), R 1 and R 2 This independently represents a functional group or atom selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group substituted with an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom. Examples of the halogen atoms include fluorine atoms and chlorine atoms. However, in general formula (3), the two R 2 These elements may be combined to form a ring structure. t independently represents an integer between 1 and 3.

[0049] Examples of compounds represented by general formula (1) in which the total number of D molecules is 1 include the following compounds.

[0050] [ka]

[0051] [ka]

[0052] [ka]

[0053] [ka]

[0054] Examples of compounds represented by general formula (1) in which the total number of D molecules is 2 include the following compounds.

[0055] [ka]

[0056] [ka]

[0057] [2] Non-hole transport polyfunctional polymers Specific examples of polyfunctional polymerizable compounds that do not exhibit hole transport properties are shown below, but are not limited to these examples.

[0058] [ka]

[0059] [ka]

[0060] In the chemical formulas of the example compounds M1 to M14 above, R represents an acryloyl group (CH2=CHCO-) ​​and R' represents a methacryloyl group (CH2=CCH3CO-).

[0061] [3] Photopolymerization initiator While there are no particular limitations on the photopolymerization initiator, for example, single-molecule photopolymerization initiators having an acylphosphine oxide structure or an O-acyloxime structure are preferred. By using these photopolymerization initiators, side effects such as a decrease in memory endurance can be more reliably suppressed. Furthermore, these photopolymerization initiators may be used individually or in combination of multiple types. In this invention, a single-molecule photopolymerization initiator refers to one that functions as a photopolymerization initiator on its own. A two-molecule photopolymerization initiator refers to one that functions as a photopolymerization initiator only when two or more molecules are present together.

[0062] Specific examples of photopolymerization initiators having an acylphosphine oxide structure are shown below.

[0063] [ka]

[0064] Of the two models mentioned above, the Ominirad819 (manufactured by IGM.Resis.BV) and the OminiradTPO (manufactured by IGM.Resis.BV), the Ominirad819 is preferable.

[0065] Furthermore, examples of photopolymerization initiators having an O-acyloxime structure include Irgacure OXE02 (manufactured by BASF Japan) and the compounds listed below.

[0066] [ka]

[0067] Furthermore, in the present invention, as a photopolymerization initiator having an O-acyloxime structure, a photopolymerization initiator having a structure represented by the following general formula (a-3) is preferred.

[0068] [ka]

[0069] In general formula (a-3), R1 and R2 each independently represent a hydrogen atom, an optionally substituted C1-C6 alkyl group, an optionally substituted C3-C6 cycloalkyl group, or an optionally substituted aryl group. R3 represents a hydrogen atom, a C1-C6 alkyl group which may have substituents, a C1-C6 alkoxy group which may have substituents, an aryl group which may have substituents, a halogen atom, a cyano group, a nitro group, a hydroxyl group, or a carbonyl group which may have substituents. Examples of alkyl groups in general formula (a-3) include methyl, ethyl, propyl, isopropyl, (t)butyl, pentyl, hexyl, octyl, dodecyl, tridecyl, tetradecyl, pentadecyl, and benzyl groups. Examples of cycloalkyl groups in general formula (a-3) include cyclopropyl, cyclobutyl, cyclopentyl, and cyclohexyl groups. Examples of aryl groups in general formula (a-3) include phenyl, p-chlorophenyl, mesityl, tolyl, xylyl, naphthyl, anthryl, azlenyl, acenaphthenyl, fluorenyl, phenanthryl, indenyl, pyrenyl, and biphenylyl groups. Furthermore, examples of alkoxy groups in general formula (a-3) include methoxy, ethoxy, propyloxy, butoxy, pentyloxy, hexyloxy, octyloxy, and dodecyloxy groups. Furthermore, these substituents may be further substituted by the substituents mentioned above, or they may be fused together to form a ring.

[0070] Specific examples of compounds having the structure represented by the above general formula (a-3) are shown below.

[0071] [ka]

[0072] [ka]

[0073] [ka]

[0074] [ka]

[0075] In addition to Irgacure OXE01 (manufactured by BASF Japan), which is the example compound B-1 mentioned above, commercially available photopolymerization initiators include PBG-305 and PBG-329 (both manufactured by Changzhou Strong Electronic New Materials Co., Ltd.). PBG-305 and PBG-329 are O-acyloxime initiators that have a disulfide structure in their compounds.

[0076] Furthermore, the photopolymerization initiator according to the present invention is not limited to the single-molecule photopolymerization initiator described above, but a bi-molecule photopolymerization initiator can also be used. Examples of bi-molecule photopolymerization initiators include a combination of a compound having a hexaarylbisimidazole structure and a thiol compound.

[0077] Specific examples of compounds having a hexaarylbisimidazole structure used as bimolecular photopolymerization initiators are shown below.

[0078] [ka]

[0079] Furthermore, specific examples of thiol compounds used as bimolecular photopolymerization initiators are shown below.

[0080] [ka]

[0081] Furthermore, the addition ratio of the photopolymerization initiator is preferably within the range of 0.1 to 10 volume percent relative to 100 volume percent of the solid content of the coating solution for forming the surface protective layer, as will be described later. In particular, it is preferable that it be within the range of 1 to 5 volume percent.

[0082] Furthermore, in addition to the photopolymerization initiators mentioned above, other known photopolymerization initiators may also be included.

[0083] [4] Metal oxide particles As described above, the protective layer according to the present invention contains metal oxide particles (large-diameter metal oxide particles) having a number-average primary particle size in the range of 150 to 550 nm. Furthermore, it is preferable that the protective layer further contains metal oxide particles (small-diameter metal oxide particles) having a number-average primary particle size in the range of 25 to 75 nm, in addition to the large-diameter metal oxide particles. The content of these large-diameter and small-diameter metal oxide particles is as described above.

[0084] As metal oxide particles, metal oxide particles including transition metals are preferred. Examples of metal oxide particles include silica (silicon dioxide), magnesium oxide, zinc oxide, lead oxide, aluminum oxide, tantalum oxide, indium oxide, bismuth oxide, yttrium oxide, cobalt oxide, copper oxide, manganese oxide, selenium oxide, iron oxide, zirconium oxide, germanium oxide, tin oxide, titanium oxide, niobium oxide, molybdenum oxide, and vanadium oxide. Among these, silica, tin oxide fine particles, titanium oxide fine particles, zinc oxide fine particles, and alumina fine particles are preferred because they can improve the wear resistance of the protective layer.

[0085] The above-mentioned metal oxide particles are preferably produced by known methods, such as general manufacturing methods including gas phase methods, chlorine methods, sulfuric acid methods, plasma methods, and electrolytic methods.

[0086] [4.1] Surface modification In the present invention, it is preferable that the metal oxide particles have reactive organic groups. That is, from the viewpoint of dispersibility and abrasion resistance of the photoreceptor, it is preferable that the surface is modified with a surface modifier having reactive organic groups.

[0087] As a surface modifier, a surface modifier that reacts with hydroxyl groups and other elements present on the surface of metal oxide particles before surface modification may be used. Examples of such surface modifiers include silane coupling agents and titanium coupling agents. Furthermore, in the present invention, it is preferable to use a surface modifier having a reactive organic group in order to further increase the hardness of the surface protective layer. It is even more preferable to use a reactive organic group that is a radical polymerizable functional group. By using a surface modifier having a radical polymerizable functional group, it reacts with the radical polymerizable binder compound and charge transport substance contained in the surface protective layer, thereby forming a strong protective film. As a surface modifier having a radically polymerizable functional group, it is preferable to use a silane coupling agent having an acryloyl group or a methacryloyl group. Examples of such surface modifiers having a radically polymerizable functional group include the known compounds listed below.

[0088] S-1: CH2=CHSi(CH3)(OCH3)2 S-2: CH2=CHSi(OCH3)3 S-3: CH2=CHSiCl3 S-4:CH2=CHCOO(CH2)2Si(CH3)(OCH3)2 S-5: CH2=CHCOO(CH2)2Si(OCH3)3 S-6:CH2=CHCOO(CH2)2Si(OC2H5)(OCH3)2 S-7: CH2=CHCOO(CH2)3Si(OCH3)3 S-8: CH2=CHCOO(CH2)2Si(CH3)Cl2 S-9: CH2=CHCOO(CH2)2SiCl3 S-10:CH2=CHCOO(CH2)3Si(CH3)Cl2 S-11: CH2=CHCOO(CH2)3SiCl3 S-12:CH2=C(CH3)COO(CH2)2Si(CH3)(OCH3)2 S-13:CH2=C(CH3)COO(CH2)2Si(OCH3)3 S-14:CH2=C(CH3)COO(CH2)3Si(CH3)(OCH3)2 S-15:CH2=C(CH3)COO(CH2)3Si(OCH3)3 S-16:CH2=C(CH3)COO(CH2)2Si(CH3)Cl2 S-17:CH2=C(CH3)COO(CH2)2SiCl3 S-18:CH2=C(CH3)COO(CH2)3Si(CH3)Cl2 S-19:CH2=C(CH3)COO(CH2)3SiCl3 S-20:CH2=CHSi(C2H5)(OCH3)2 S-21:CH2=C(CH3)Si(OCH3)3 S-22:CH2=C(CH3)Si(OC2H5)3 S-23:CH2=CHSi(OCH3)3 S-24:CH2=C(CH3)Si(CH3)(OCH3)2 S-25:CH2=CHSi(CH3)Cl2 S-26:CH2=CHCOOSi(OCH3)3 S-27:CH2=CHCOOSi(OC2H5)3 S-28:CH2=C(CH3)COOSi(OCH3)3 S-29:CH2=C(CH3)COOSi(OC2H5)3 S-30:CH2=C(CH3)COO(CH2)3Si(OC2H5)3 S-31:CH2=CHCOO(CH2)2Si(CH3)2(OCH3) S-32:CH2=CHCOO(CH2)2Si(CH3)(OCOCH3)2 S-33:CH2=CHCOO(CH2)2Si(CH3)(ONHCH3)2 S-34:CH2=CHCOO(CH2)2Si(CH3)(OC6H5)2 S-35:CH2=CHCOO(CH2)2Si(C 10 H 21 )(OCH3)2 S-36:CH2=CHCOO(CH2)2Si(CH2C6H5)(OCH3)2

[0089] In addition to S-1 to S-36 above, silane compounds having reactive organic groups capable of radical polymerization can be used as surface modifiers. These surface modifiers can be used individually or in combination of two or more.

[0090] Furthermore, while there are no particular restrictions on the amount of surface modifier used, it is preferable that it be in the range of 0.1 to 100 parts by mass per 100 parts by mass of metal oxide particles before modification.

[0091] [4.2] Method for surface modification of metal oxide particles Specifically, surface modification of metal oxide particles involves wet grinding a slurry (suspension of solid particles) containing the metal oxide particles before modification and a surface modifier. This process refines the metal oxide particles while simultaneously advancing surface modification. The surface modification is then completed by removing the solvent and pulverizing the mixture.

[0092] The slurry is preferably a mixture of 100 parts by mass of metal oxide particles before modification, with 0.1 to 100 parts by mass of a surface modifier and 50 to 5000 parts by mass of a solvent.

[0093] Another example of equipment used for wet grinding of slurries is a wet media dispersion type apparatus. A wet media dispersion apparatus is a device that fills a container with beads as a media and then rotates a stirring disc mounted perpendicular to the rotating shaft at high speed. This process crushes and disperses aggregated metal oxide particles. The apparatus configuration should be such that it can sufficiently disperse the metal oxide particles and perform surface modification. Various types of apparatus can be used, such as vertical or horizontal, continuous or batch-type. Specifically, sand mills, ultravisco mills, pearl mills, grain mills, dyno mills, agitator mills, dynamic mills, etc., can be used. These dispersion devices use grinding media such as balls and beads to perform fine grinding and dispersion by impact crushing, friction, shear, shear stress, etc.

[0094] For use in a wet media dispersion apparatus, beads made from materials such as glass, alumina, zircon, zirconia, steel, and flint can be used. Zirconia or zircon beads are particularly preferred. Typically, beads with a diameter of 1-2 mm are used. In this invention, for example, beads with a diameter of 0.1-1.0 mm are preferred.

[0095] Various materials can be used for the discs and inner walls of containers used in wet media dispersion apparatuses, such as stainless steel, nylon, and ceramic. In this invention, it is particularly preferable to use ceramic discs and inner walls of containers made of zirconia or silicon carbide.

[0096] [5] Other additives In addition to [1] a polyfunctional polymerizable compound having hole transport properties, a monofunctional polymerizable compound having hole transport properties, [2] a polyfunctional polymerizable compound that does not have hole transport properties, [3] a photopolymerization initiator, and [4] inorganic particles, the surface protective layer according to the present invention may also contain other components, such as known charge transport substances, various antioxidants, and various lubricant particles such as fluorine atom-containing resin particles.

[0097] As a known charge transport material, for example, the charge transport material described in paragraphs

[0064] to

[0108] of Japanese Patent Publication No. 2018-124489 can be used.

[0098] As fluorine atom-containing resin particles, it is preferable to appropriately select one or more from among, for example, tetrafluoroethylene resin, trifluoroethylene chloride resin, hexafluoroethylene chloride propylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluoroethylene chloride resin, and copolymers thereof. Tetrafluoroethylene resin and vinylidene fluoride resin are particularly preferred.

[0099] <Conductive support> The conductive support can be anything that is conductive. Examples of conductive supports include metals such as aluminum, copper, chromium, nickel, zinc, and stainless steel formed into drums or sheets; metal foils such as aluminum or copper laminated onto a plastic film; aluminum, indium oxide, tin oxide, etc., deposited onto a plastic film; and metals, plastic films, or paper coated with a conductive substance alone or together with a binder resin to form a conductive layer.

[0100] <Middle class> In the photoreceptor according to the present invention, an intermediate layer having barrier and adhesive functions can be provided between the conductive support and the photosensitive layer. Considering various factors such as preventing malfunctions, it is preferable to provide an intermediate layer.

[0101] Such an intermediate layer may, for example, contain a binder resin (hereinafter also referred to as "intermediate layer binder resin") and, if necessary, conductive particles or metal oxide particles.

[0102] Examples of binder resins for the intermediate layer include casein, polyvinyl alcohol, nitrocellulose, ethylene-acrylic acid copolymer, polyamide resin, polyurethane resin, and gelatin. Among these, alcohol-soluble polyamide resins are preferred.

[0103] The intermediate layer can contain various conductive particles or metal oxide particles for the purpose of adjusting resistance. For example, various metal oxide particles such as alumina, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide can be used. In addition, ultrafine particles such as tin-doped indium oxide, antimony-doped tin oxide, or zirconium oxide can be used.

[0104] The number-average primary particle size of such metal oxide particles is preferably 0.3 μm or less, and more preferably 0.1 μm or less. The number-average primary particle size of the metal oxide particles can be measured by the same method as the method for measuring the number-average primary particle size of metal oxide particles contained in a surface protective layer. These metal oxide particles may be used individually or in mixtures of two or more types. When two or more types are mixed, they may take the form of a solid solution or fusion. The content of conductive particles or metal oxide particles is preferably in the range of 20 to 400 parts by mass per 100 parts by mass of the intermediate layer binder resin. In particular, it is preferably in the range of 50 to 350 parts by mass.

[0105] The thickness of the intermediate layer is preferably in the range of 0.1 to 15 μm, and more preferably in the range of 0.3 to 10 μm.

[0106] <Charge generation layer> The charge generation layer contains a charge generation material and a binder resin (hereinafter also referred to as "binder resin for charge generation layer").

[0107] Examples of charge-generating materials include, but are not limited to, azo raw materials such as Sudan Red and Diane Blue, quinone pigments such as pyrenequinone and anthantrone, quinocyanine pigments, perylene pigments, indigo pigments such as indigo or thioindigo, polycyclic quinone pigments such as pyranthrone and diphthaloylpyrene, and phthalocyanine pigments. Among these, polycyclic quinone pigments and titanylphthalocyanine pigments are preferred. These charge-generating materials may be used individually or in combination of two or more.

[0108] Any known resin can be used as the binder resin for the charge generation layer. For example, 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, or copolymer resins containing two or more of these resins (for example, vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin), poly-vinylcarbazole resin, etc., but are not limited to these. Among these, polyvinyl butyral resin is preferred.

[0109] The content ratio of the charge generating material in the charge generating layer is preferably in the range of 1 to 600 parts by mass per 100 parts by mass of the binder resin for the charge generating layer. In particular, it is preferably in the range of 50 to 500 parts by mass.

[0110] The thickness of the charge generation layer varies depending on the properties of the charge generation material, the properties and content ratio of the binder resin for the charge generation layer, etc., but is preferably in the range of 0.01 to 5 μm. In particular, it is preferably in the range of 0.05 to 3 μm.

[0111] <Charge transport layer> The charge transport layer contains a charge transport material and a binder resin (hereinafter also referred to as "binder resin for charge transport layer").

[0112] Examples of charge transport materials for the charge transport layer include triphenylamine derivatives, hydrazone compounds, styryl compounds, benzidine compounds, and butadiene compounds.

[0113] Any known resin can be used as the binder resin for the charge transport layer. Examples of binder resins for the charge transport layer include 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, polycarbonate resins of the BPA (bisphenol A) type, BPZ (bisphenol Z) type, dimethyl BPA type, and BPA-dimethyl BPA copolymer type are preferred in terms of crack resistance, abrasion resistance, and electrostatic properties.

[0114] The content ratio of the charge transport material in the charge transport layer is preferably in the range of 10 to 500 parts by mass, and more preferably in the range of 20 to 250 parts by mass, per 100 parts by mass of the binder resin for the charge transport layer.

[0115] The thickness of the charge transport layer varies depending on the properties of the charge transport material, the properties and content ratio of the binder resin for the charge transport layer, etc., but it is preferably in the range of 5 to 40 μm. In particular, it is preferably in the range of 10 to 30 μm.

[0116] For example, antioxidants, electronically conductive agents, stabilizers, silicone oils, etc., may be added to the charge transport layer. Preferably, antioxidants are those disclosed in Japanese Patent Publication No. 2000-305291, and electronically conductive agents are those disclosed in Japanese Patent Publication Nos. 50-137543 and 58-76483, etc.

[0117] [Manufacturing method for electrophotographic photoreceptors] The photoreceptor according to the present invention can be manufactured, for example, by following the steps described below.

[0118] Step (1): A step of forming an intermediate layer by applying a coating solution for forming an intermediate layer to the outer surface of a conductive support and drying it. Step (2): A step of forming a charge generation layer by applying a coating solution for forming a charge generation layer to the outer surface of an intermediate layer formed on a conductive support and drying it. Step (3): A step in which a charge transport layer is formed by applying a coating solution for forming a charge transport layer to the outer surface of the charge generating layer formed on the intermediate layer and drying it. Step (4): A step to form a protective layer by applying a coating liquid for forming a protective layer to the outer surface of the charge transport layer formed on the charge generation layer, forming a coating film, and curing this coating film by irradiating it with ultraviolet light.

[0119] The following describes each step.

[0120] <Process (1): Formation of the intermediate layer> The intermediate layer is formed by dissolving an intermediate layer binder resin in a solvent to prepare a coating solution (hereinafter also referred to as the "intermediate layer forming coating solution"). Conductive particles or metal oxide particles are dispersed as needed. Subsequently, the coating solution is applied to a conductive support to a certain thickness to form a coating film, and the coating film is dried to form the intermediate layer.

[0121] As means of dispersing conductive particles or metal oxide particles in the coating solution for forming the intermediate layer, for example, an ultrasonic disperser, a ball mill, a sand mill, a homomixer, etc., can be used, but are not limited to these.

[0122] Examples of known methods for applying the coating solution for forming the intermediate layer include immersion coating, spray coating, spinner coating, bead coating, blade coating, beam coating, slide hopper method, and circular slide hopper method.

[0123] The drying method for the coating film can be appropriately selected depending on the type of solvent, film thickness, etc., but heat drying is preferred.

[0124] The solvent used in the intermediate layer formation process can be any solvent that effectively disperses conductive particles and metal oxide particles and dissolves the intermediate layer binder resin. Specifically, for example, C1-C4 alcohols such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, and sec-butanol are preferred because they exhibit excellent solubility and coating performance for the binder resin. Furthermore, to improve preservation and particle dispersibility, it is preferable to use a co-solvent that can be used in combination with the above solvent and provides desirable effects. Examples of co-solvents include benzyl alcohol, toluene, dichloromethane, cyclohexanone, and tetrahydrofuran.

[0125] The concentration of the intermediate layer binder resin in the intermediate layer forming coating solution is appropriately selected according to the thickness of the intermediate layer and the production speed.

[0126] <Step (2): Formation of charge generation layer> The charge generation layer is prepared by dispersing a charge generation substance in a solution in which a binder resin for the charge generation layer is dissolved in a solvent, thereby creating a coating solution (hereinafter also referred to as the "coating solution for forming the charge generation layer"). This coating solution is then applied to the intermediate layer to a certain thickness to form a coating film, and the coating film is dried to form the charge generation layer.

[0127] As means of dispersing the charge-generating substance in the coating solution for forming the charge-generating layer, for example, an ultrasonic disperser, a ball mill, a sand mill, a homomixer, etc., can be used, but are not limited to these.

[0128] Examples of known methods for applying the coating solution for forming the charge generation layer include immersion coating, spray coating, spinner coating, bead coating, blade coating, beam coating, slide hopper method, and circular slide hopper method.

[0129] The drying method for the coating film can be appropriately selected depending on the type of solvent, film thickness, etc., but heat drying is preferred.

[0130] Examples of solvents used to form the charge generation layer include, but are not limited to, toluene, xylene, dichloromethane, 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, 1,4-dioxane, 1,3-dioxolane, pyridine, and diethylamine.

[0131] <Step (3): Formation of the charge transport layer> The charge transport layer can be formed by preparing a coating solution (hereinafter also referred to as the "charge transport layer forming coating solution") in which a binder resin for the charge transport layer and a charge transport substance are dissolved in a solvent. Then, this coating solution is applied to the charge generating layer to a certain thickness to form a coating film, and the coating film is dried.

[0132] Examples of known methods for applying the coating solution for forming the charge transport layer include immersion coating, spray coating, spinner coating, bead coating, blade coating, beam coating, slide hopper method, and circular slide hopper method.

[0133] The drying method for the coating film can be appropriately selected depending on the type of solvent, film thickness, etc., but heat drying is preferred.

[0134] Examples of solvents used for forming the charge transport layer include, but are not limited to, toluene, xylene, dichloromethane, 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.

[0135] <Process (4): Formation of surface protective layer> To form the surface protective layer, first, a coating solution is prepared containing a charge-transporting compound (polymerizable compound) having at least a polymerizable functional group in its molecule, a photopolymerization initiator, and metal oxide particles (large-diameter metal oxide particles). If necessary, known charge-transporting substances or small-diameter metal oxide particles are added to the coating solution. Then, the coating solution is cured by irradiation with ultraviolet light to form the surface protective layer.

[0136] Specifically, for example, a coating solution (hereinafter also referred to as "coating solution for forming a surface protective layer") is prepared by adding at least one of a polyfunctional polymerizable compound having hole transport properties, a polyfunctional polymerizable compound not having hole transport properties, and a monofunctional polymerizable compound having hole transport properties, along with a photopolymerization initiator, metal oxide particles (large-diameter metal oxide particles), and other components as needed, to a known solvent. Then, this coating solution for forming a surface protective layer is applied to the outer surface of the charge transport layer formed in step (3) to form a coating film. Subsequently, the coating film is dried and the polymerizable compounds in the coating film are cured by irradiation with ultraviolet light to form a surface protective layer.

[0137] In the curing treatment of the surface protective layer, the coating film is irradiated with ultraviolet light to generate radicals. Then, the polyfunctional polymerizable compound is subjected to a polymerization reaction, and crosslinking bonds are formed through intermolecular and intramolecular crosslinking reactions, thereby curing the material. Preferably, the polyfunctional polymerizable compound is formed as a crosslinking-type curable resin.

[0138] Specifically, the hole-transporting polyfunctional polymerizable compound is preferably in the range of 60 to 99 volume percent relative to 100 volume percent of the solid content of the coating liquid for forming the surface protective layer. The hole-transporting monofunctional polymerizable compound is preferably in the range of 10 to 49 volume percent. The non-hole-transporting polyfunctional polymerizable compound is preferably in the range of 51 to 90 volume percent. Furthermore, the coating solution for forming the surface protective layer contains metal oxide particles with a number-average primary particle size of 150 to 550 nm in an amount of 1 to 30% by volume, relative to 100% by volume of solid content. Furthermore, it is preferable that the coating liquid for forming the surface protective layer contains metal oxide particles with a number average primary particle size of 25 to 75 nm in an amount of 5 to 15 volume% per 100 volume% of solid content. The photopolymerization initiator is preferably contained in an amount of 1 to 5% by volume relative to 100% by volume of the solid content of the coating solution for forming the surface protective layer.

[0139] As means of dispersing inorganic particles and charge transport materials in a coating liquid for forming a surface protective layer, for example, an ultrasonic disperser, a ball mill, a sand mill, a homomixer, etc., can be used, but are not limited to these.

[0140] Any solvent can be used to form the surface protective layer, as long as it can dissolve or disperse a polyfunctional polymerizable compound having or not having hole-transporting properties, a photopolymerization initiator, a monofunctional polymerizable compound having hole-transporting properties, a charge transport substance, metal oxide particles, etc. Examples include, but are not limited to, methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, sec-butanol, benzyl alcohol, toluene, xylene, dichloromethane, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, pyridine, diethylamine, etc.

[0141] Examples of known methods for applying the protective layer coating solution include immersion coating, spray coating, spinner coating, bead coating, blade coating, beam coating, slide hopper method, and circular slide hopper method.

[0142] While the coating film may be cured without drying, it is preferable to perform the curing treatment after natural drying or heat drying.

[0143] Drying conditions can be appropriately selected depending on the type of solvent, film thickness, etc. The drying temperature is preferably in the range of room temperature (25°C) to 180°C, and particularly preferably in the range of 80°C to 140°C. The drying time is preferably 1 to 200 minutes, and particularly preferably 5 to 100 minutes.

[0144] Any light source that emits ultraviolet light can be used without restriction. 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 (pulsed) xenon lamps can be used. Irradiation conditions vary depending on the lamp, but for example, the amount of ultraviolet radiation is typically 0.01 to 5 J / cm². 2 Within the range of preferably 0.1 to 3 J / cm² 2 It is within the range. The power of the lamp is preferably in the range of 0.1 to 5 kW, and particularly preferably in the range of 0.5 to 3 kW.

[0145] For obtaining the required amount of ultraviolet light, the irradiation time is preferably, for example, 0.1 seconds to 10 minutes, and more preferably 0.1 seconds to 5 minutes from the viewpoint of work efficiency. Furthermore, the integrated energy of the light irradiation is 1-3 J / cm². 2 It is preferably within the range of 1.5 to 2.5 J / cm². 2 It is more preferable that it be within the range.

[0146] In the process of forming the surface protective layer, drying can be performed before, during, and after irradiation with ultraviolet light, and the timing of drying can be appropriately selected by combining these methods.

[0147] [Cleaning Blade] The electrophotographic image forming system of the present invention has means for cleaning the photoreceptor by bringing the tip edge of a cleaning blade, which has an obtuse edge angle, into contact with the photoreceptor.

[0148] <Edge angle> The edge angle is preferably in the range of 90 to 130°, and more preferably in the range of 95 to 105°. In the present invention, the edge angle is the angle θ shown in Figure 1. e As shown, this is the angle of the tip edge portion of the rubber material that is in contact with the surface of the photoreceptor, C.

[0149] Figure 1 is a conceptual diagram showing the relationship between the cleaning blade and the electrophotographic photoreceptor according to the present invention, viewed from the side. As shown in Figure 1, the cleaning blade described above has an edge angle θ e The tip edge is positioned so as to contact the surface of the photoreceptor 10 so that it falls within the above range. The portion of the tip edge that contacts the surface of the photoreceptor 10 is called the contact portion C. Cleaning Blade C L The wedge angle θ3, which is the angle between the tip surface and the cotangent line, is an acute angle.

[0150] The aforementioned edge angle θ e When the angle is 90° or greater, the wedge angle θ3 becomes smaller. As a result, a shearing action is obtained near the blade nip that cleaves and extends the layered crystals of the fatty acid metal salt, thereby improving surface lubricity.

[0151] The aforementioned edge angle θ e If the angle is greater than 130°, the wedge angle θ3 becomes too small, causing the interposed toner particles and external additive particles to be pressed perpendicularly to the photoreceptor surface near the blade nip, resulting in excessive abrasiveness and insufficient lubrication. Furthermore, the intervening particles exert a greater force pushing the blade vertically upward, which may lead to inadequate cleaning.

[0152] Here, the definitions of each term in the context of cleaning blades are as follows: (Contact force) The contact force is applied to the cleaning blade C at the contact point C. L When the cleaning blade C is brought into contact with the surface of the photoreceptor 10, LThis is the force applied to the surface of the photoreceptor 10 as a result of applying a load.

[0153] (Effective contact angle) The effective contact angle is the angle between the rubber material and the downstream edge of the image carrier in the rotational direction when the rubber material is bent due to being pressed against the image carrier, as shown in Figure 1, with respect to the cleaning blade C L This is the actual angle θ1 between the tip of the tip and the surface of the photoreceptor 10. Cleaning Blade C L Preferably, the effective contact angle is within the range of 7 to 20°. The effective contact angle θ1 is the cleaning blade C L The deflection can be determined by calculating it using the cross-sectional shape and material properties such as the Young's modulus of the material.

[0154] (Rigid body contact angle) The rigid contact angle is the cleaning blade C L This is the design value used when bringing the photoreceptor into contact with the surface of the photoreceptor. Note that the angle θ2 shown in Figure 1 is the cleaning blade C L Assuming that the cleaning blade C is a rigid body (shown by the dotted line), L This is the rigid contact angle formed between the tip of the tip and the surface of the photoreceptor 10.

[0155] (free length) The free length is the rubber material and the sheet metal P g This is the length of the part that protrudes from the sheet metal P. g This is the part L in Figure 1, excluding the adhesive portion.

[0156] (wedge angle) The wedge angle is the angle between the rubber material and the ridge on the upstream side in the rotational direction of the photoreceptor 10, as shown by angle θ3 in Figure 1.

[0157] <Cleaning blade configuration> Cleaning blade C according to the present invention L It is mainly composed of rubber material. The rubber material does not need to be entirely the same; for example, it may be a two-layer blade consisting of a contact layer that forms the edge and a support layer. In the case of a two-layer structure, for example, a material with a lower permanent strain than the contact layer material may be used as the material for the support layer to suppress sagging.

[0158] (Material) Cleaning blade C according to the present invention L From the viewpoint of abrasion resistance and moldability, urethane rubber is preferred as the material.

[0159] (hardness) Cleaning blade C according to the present invention L The rubber hardness is preferably within the range of 65 to 85° according to the hardness values ​​specified in JIS-A. If the rubber hardness is 65° or higher, the blade will not be easily pulled in, and the wedge angle θ3 will not become too small. If the rubber hardness is 85° or less, the surface pressure will not increase, and the abrasive force will not become too strong. As a result, the removal of fatty acid metal salts will be less difficult, and sufficient lubrication will be achieved.

[0160] (Rebound elasticity) Cleaning blade C according to the present invention L The rebound elasticity is preferably in the range of 10 to 40°. If the rebound elasticity is within the above range, vibrations are moderately suppressed, the wedge angle θ3 becomes stable, and the shear action of the fatty acid metal salt can be expressed more effectively.

[0161] (shape) Cleaning blade C according to the present invention L The free length L is preferably in the range of 8.5 to 11.5 mm, and the thickness d is preferably in the range of 1.7 to 2.5 mm.

[0162] (Contact condition) Cleaning blade C according to the present invention LThe contact force is preferably in the range of 12 to 30 (N / m) from the viewpoint of preventing residue and peeling. If the contact force is 12 N / m or more, there is no risk of residue being left behind, and if it is 30 N / m or less, there is no risk of peeling.

[0163] [Toner for developing electrostatic images] The electrostatic image developing toner (also simply referred to as "toner") used in the image forming system of the present invention comprises toner matrix particles and an external additive attached to the surface of the toner matrix particles. In particular, it is characterized by containing at least a lubricant on the surface of the toner particles as an external additive. In this specification, "toner matrix particles" refers to the particles that constitute the matrix of "toner particles". The "toner matrix particles" contain at least a binder resin and may also contain other components as needed, such as colorants, release agents (waxes), and charge control agents. Particles formed by adding an external additive to the surface of "toner matrix particles" and allowing it to adhere are generally referred to as "toner particles." However, when the toner matrix particles themselves are used without adding external additives to make them adhere, the toner matrix particles themselves may also be referred to as "toner particles." Furthermore, "toner" refers to an aggregate of "toner particles."

[0164] <Toner matrix particles> As the toner matrix particles according to the present invention, known toner matrix particles can be used. Specifically, such toner matrix particles consist of toner matrix particles containing at least a binder resin and, optionally, a colorant. Furthermore, these toner matrix particles may also contain other components, such as release agents and charge control agents, as needed.

[0165] (Binding resin) As the binder resin, any known resin can be used, and for example, amorphous resins and crystalline resins can be suitably used. In particular, it is preferable that the material contains styrene-acrylic resin and crystalline polyester resin, as described later.

[0166] (Amorphous resin) The amorphous resins that can be used in the present invention are not particularly limited, but in addition to vinyl resins and polyester resins as described below, known amorphous resins such as urethane resins and urea resins can be preferably used.

[0167] (Vinyl resin) When using vinyl resin as the amorphous resin, the vinyl resin is not particularly limited as long as it is a polymer of vinyl compounds. Examples of such vinyl resins include acrylic ester resins, styrene-acrylic ester resins, and ethylene-vinyl acetate resins. These may be used individually or in combination of two or more types. Among the vinyl resins mentioned above, styrene-acrylic ester resin (styrene-acrylic resin) is preferred when considering its plasticity during heat fixing. Therefore, although a detailed explanation will be omitted, it is preferable to use styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, and p-ethylstyrene as styrene monomers; and acrylic acid ester monomers such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, and isobutyl acrylate as (meth)acrylic acid ester monomers; and methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, and isobutyl methacrylate. These styrene monomers and (meth)acrylic acid ester monomers can be used individually or in combination of two or more.

[0168] In addition, other monomers may be polymerized. Examples thereof include, for example, acrylic acid, methacrylic acid, maleic acid, itaconic acid, cinnamic acid, fumaric acid, maleic acid monoalkyl ester, itaconic acid monoalkyl ester, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, and the like. The method for producing the styrene-acrylic resin is not particularly limited and can be produced by an emulsion polymerization method or the like.

[0169] (Amorphous polyester resin) When a polyester resin is used as the amorphous resin, the amorphous polyester resin refers to the following resin. The amorphous polyester resin refers to a resin that does not show a distinct endothermic peak in differential scanning calorimetry (DSC) among known polyester resins obtained by polycondensation reaction of a dicarboxylic acid or higher (polyvalent carboxylic acid) and a diol or higher (polyvalent alcohol). Specifically, the distinct endothermic peak means a peak having a half-width of the endothermic peak within 15 °C when measured at a heating rate of 10 °C / min in differential scanning calorimetry (DSC).

[0170] Examples of the polyvalent carboxylic acid include aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,11-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, 1,18-octadecanedicarboxylic acid; aromatic dicarboxylic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid; aliphatic unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, isododecenyl succinic acid, n-dodecenyl succinic acid, n-octenyl succinic acid; polyvalent carboxylic acids having a valency of 2 or more such as trimellitic acid, pyromellitic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, pyrenetricarboxylic acid, pyrenetetracarboxylic acid, etc.

[0171] Examples of the polyhydric alcohol include aliphatic diols such as ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, 1,20-eicosanediol; bisphenols such as bisphenol A and bisphenol F, and alkylene oxide adducts of bisphenols such as ethylene oxide adducts and propylene oxide adducts thereof; polyols having a valency of 3 or more such as glycerin, pentaerythritol, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, tetraethylolbenzoguanamine, etc.

[0172] (Crystalline resin) The toner matrix particles according to the present invention may contain a crystalline resin, and for example, the crystalline polyester described below can be suitably used. In addition, crystalline resins described in paragraphs 0043 to 0102 of Japanese Patent Application Publication No. 2015-011325 can be suitably used. In particular, the inclusion of a hybrid crystalline polyester resin is preferable from a manufacturing standpoint.

[0173] (Crystalline polyester resin) Crystalline polyester resin refers to a portion derived from a known polyester resin obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polycarboxylic acid) and a divalent or higher alcohol (polyhydric alcohol), and which exhibits a clear endothermic peak rather than a stepwise endothermic change in differential scanning calorimetry (DSC) of toner. A clear endothermic peak specifically refers to a peak in differential scanning calorimetry (DSC) where, when measured at a heating rate of 10°C / min, the full width at half maximum (FMAX) of the endothermic peak is within 15°C.

[0174] The crystalline polyester resin is not particularly limited as long as it is defined as described above. For example, it may contain crystalline polyester resin itself. Alternatively, the hybrid resin may include a resin having a structure in which other components are copolymerized to a main chain of crystalline polyester resin units. Alternatively, the hybrid resin may include a resin having a structure in which crystalline polyester resin units are copolymerized to a main chain of other components, and the toner containing this resin exhibits a clear endothermic peak as described above.

[0175] Crystalline polyester resins are produced from polycarboxylic acid components and polyhydric alcohol components. In this case, the valency of the polycarboxylic acid component and the polyhydric alcohol component is preferably 2 to 3, and particularly preferably 2.

[0176] A crystalline polyester resin can be formed by polycondensing (esterifying) the above-mentioned polycarboxylic acid and polyhydric alcohol using a known esterification catalyst. However, the method for forming a crystalline polyester resin is not limited to this.

[0177] The preferred ratio of the polyhydric alcohol component to the polyhydric carboxylic acid component is such that the equivalent ratio [OH] / [COOH] of the hydroxyl group [OH] of the diol component to the carboxyl group [COOH] of the dicarboxylic acid component is 1.5 / 1 to 1 / 1.5. More preferably, the ratio [OH] / [COOH] is 1.2 / 1 to 1 / 1.2.

[0178] Examples of catalysts that can be used in the production of crystalline polyester resins include alkali metal compounds such as sodium and lithium; alkaline earth metal compounds such as magnesium and calcium; metal compounds such as aluminum, zinc, manganese, antimony, titanium, tin, zirconium, and germanium; phosphite compounds; phosphate compounds; and amine compounds.

[0179] Specifically, examples of tin compounds include dibutyltin oxide, tin octoate, tin dioctoate, and their salts. Examples of titanium compounds include titanium alkoxides such as tetran-butyl titanate, tetraisopropyl titanate, tetramethyl titanate, and tetrastearyl titanate; titanium acylates such as polyhydroxytitanium stearate; and titanium chelates such as titanium tetraacetylacetonate, titanium lactate, and titanium triethanolamine. Examples of germanium compounds include germanium dioxide. Furthermore, examples of aluminum compounds include oxides such as polyaluminum hydroxide, aluminum alkoxides, and tributylaluminate. These may be used individually or in combination of two or more.

[0180] The polymerization temperature and polymerization time are not particularly limited, and the reaction system may be subjected to reduced pressure during polymerization as needed.

[0181] Furthermore, in the case of a hybrid resin having crystalline polyester resin units, the content of crystalline polyester resin units is preferably in the range of 50 to 98% by mass relative to the total amount of the hybrid resin. By setting the range as described above, sufficient crystallinity can be imparted to the hybrid resin. Furthermore, the constituent components and their proportions in each unit within the hybrid resin can be determined, for example, by NMR measurement or methylation reaction P-GC / MS measurement.

[0182] Here, the hybrid resin includes, in addition to the crystalline polyester resin unit described above, amorphous resin units other than polyester resin, as detailed below. The hybrid resin may be in any form, such as a block copolymer or a graft copolymer, as long as it contains the above-mentioned crystalline polyester resin unit and amorphous resin unit other than polyester resin. In particular, the hybrid resin is preferably a graft copolymer. By using a graft copolymer, the orientation of the crystalline polyester resin units can be easily controlled, and sufficient crystallinity can be imparted to the hybrid resin.

[0183] Furthermore, from the above viewpoint, it is preferable that the crystalline polyester resin unit is grafted with amorphous resin units other than crystalline polyester resin as the main chain. In other words, the hybrid crystalline polyester resin is preferably a graft copolymer having amorphous resin units other than polyester resin as the main chain and crystalline polyester resin units as the side chains.

[0184] By adopting the above configuration, the orientation of the crystalline polyester resin units can be further enhanced, thereby improving the crystallinity of the hybrid resin.

[0185] In addition, substituents such as sulfonic acid groups, carboxy groups, urethane groups, etc. may be further introduced into the hybrid resin. The introduction of the above substituents may be carried out in the crystalline polyester resin unit or in an amorphous resin unit other than the polyester resin described in detail below.

[0186] (Amorphous resin unit other than polyester resin) The amorphous resin unit other than the polyester resin is a part derived from an amorphous resin other than the above crystalline polyester resin. Containing an amorphous resin unit in the hybrid resin (furthermore, in the toner), due to its structure, an appropriate analysis method can be selected from NMR measurement, P-GC / MS measurement, methylation reaction P-GC / MS measurement, etc., and the chemical structure can be specified.

[0187] The amorphous resin unit is a resin unit that does not have a melting point and has a relatively high first glass transition point (Tg) when differential scanning calorimetry (DSC) is performed on a resin having the same chemical structure and molecular weight as the unit.

[0188] The amorphous resin unit is not particularly limited as long as it satisfies the above definition. For example, for a resin having a structure in which other components are copolymerized in the main chain composed of an amorphous resin unit or a resin having a structure in which an amorphous resin unit is copolymerized in the main chain composed of other components, if the toner containing this resin has the above amorphous resin unit, the resin corresponds to a hybrid resin having an amorphous resin unit.

[0189] The amorphous resin unit is preferably composed of a resin of the same kind as the amorphous resin contained in the binder resin (that is, a resin other than the hybrid resin). By adopting such a form, the affinity between the hybrid resin and the amorphous resin is further improved, the hybrid resin is more easily incorporated into the amorphous resin, and the charge uniformity etc. are further improved.

[0190] Here, "same type of resin" means that characteristic chemical bonds are commonly found in the repeating units. Furthermore, "characteristic chemical bonds" follow the "polymer classification" described in the National Institute for Materials Science (NIMS) Materials Database (http: / / polymer.nims.go.jp / PoLyInfo / guide / jp / term_polymer.html). In other words, the chemical bonds that constitute polymers classified into a total of 22 types—polyacrylic, polyamide, polyanhydride, polycarbonate, polydiene, polyester, polyhaloolefin, polyimide, polyimine, polyketone, polyolefin, polyether, polyphenylene, polyphosphazene, polysiloxane, polystyrene, polysulfide, polysulfone, polyurethane, polyurea, polyvinyl, and other polymers—are called "characteristic chemical bonds."

[0191] When the resin is a copolymer, "the same type of resin" refers to the following: In other words, in the chemical structures of multiple monomer species that make up the copolymer, if the monomer species having the above-mentioned chemical bond are used as constituent units, it refers to resins that share the characteristic chemical bond. Therefore, even if the properties exhibited by the resins themselves differ from each other, or if the molar ratios of the monomer species constituting the copolymer differ from each other, they are considered to be the same type of resin if they share a characteristic chemical bond.

[0192] For example, a resin (or resin unit) formed from styrene, butyl acrylate, and acrylic acid, and a resin (or resin unit) formed from styrene, butyl acrylate, and methacrylic acid, both share at least the chemical bonds that constitute polyacrylic. Therefore, they are the same type of resin. To give a further example, a resin (or resin unit) formed from styrene, butyl acrylate, and acrylic acid, and a resin (or resin unit) formed from styrene, butyl acrylate, acrylic acid, terephthalic acid, and fumaric acid, both share a common chemical bond, which is at least the chemical bond that constitutes polyacrylic. Therefore, these are the same type of resin.

[0193] The resin components constituting the amorphous resin unit are not particularly limited, but examples include vinyl resin units, urethane resin units, and urea resin units. Among these, vinyl resin units are preferred because they allow for easy control of thermoplasticity. The vinyl resin unit is not particularly limited as long as it is obtained by polymerizing vinyl compounds. Examples include acrylic ester resin units, styrene-acrylic ester resin units, and ethylene-vinyl acetate resin units. These may be used individually or in combination of two or more types.

[0194] The method for forming styrene-acrylic resin units is not particularly limited, and includes methods of polymerizing monomers using known oil-soluble or water-soluble polymerization initiators. Oil-soluble polymerization initiators include, specifically, the azo-based or diazo-based polymerization initiators and peroxide-based polymerization initiators listed below.

[0195] Examples of azo or diazo polymerization initiators include 2,2′-azobis-(2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis(cyclohexane-1-carbonitride), 2,2′-azobis-4-methoxy-2,4-dimethylvaleronitrile, and azobisisobutyronitrile.

[0196] Examples of peroxide-based polymerization initiators include benzoyl peroxide, methyl ethyl ketone peroxide, diisopropyl peroxycarbonate, cumene hydroperoxide, t-butyl hydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2,4-dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis-(4,4-t-butylperoxycyclohexyl)propane, and tris-(t-butylperoxy)triazine.

[0197] Furthermore, when forming resin particles by emulsion polymerization, water-soluble radical polymerization initiators can be used. Examples of water-soluble polymerization initiators include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, and hydrogen peroxide.

[0198] The content of amorphous resin units is preferably in the range of 3 to 50% by mass relative to the total amount of hybrid resin. Furthermore, the above content is more preferably in the range of 5 to 30% by mass. By setting the range as described above, sufficient crystallinity can be imparted to the hybrid resin.

[0199] (Method for producing hybrid crystalline polyester resin (hybrid resin)) The method for producing the hybrid resin contained in the binder resin according to the present invention is not particularly limited. The production method can be any method that can form a polymer having a structure in which the crystalline polyester resin unit and the amorphous resin unit are molecularly bonded. Specific manufacturing methods for hybrid resins include, for example, the methods shown below.

[0200] (1) A method for producing a hybrid resin by pre-polymerizing amorphous resin units and carrying out a polymerization reaction in the presence of the amorphous resin units to form crystalline polyester resin units. In this method, first, monomers constituting the amorphous resin unit described above are subjected to an addition reaction to form the amorphous resin unit. Preferably, the monomers are vinyl monomers such as styrene monomer and (meth)acrylic acid ester monomer. Next, a crystalline polyester resin unit is formed by polymerizing a polycarboxylic acid and a polyhydric alcohol in the presence of an amorphous resin unit. At this time, a polycarboxylic acid and a polyhydric alcohol are condensed together, and a polycarboxylic acid or polyhydric alcohol is added to the amorphous resin unit. This forms a hybrid resin.

[0201] In the above method, it is preferable to incorporate into the crystalline polyester resin unit or amorphous resin unit parts that are capable of reacting with each other. Specifically, when forming amorphous resin units, in addition to the monomers constituting the amorphous resin units, compounds having sites that can react with carboxyl groups [-COOH] or hydroxyl groups [-OH] remaining in the crystalline polyester resin units, as well as sites that can react with the amorphous resin units, are also used. In other words, this compound reacts with carboxyl groups [-COOH] or hydroxyl groups [-OH] in the crystalline polyester resin unit. As a result, the crystalline polyester resin unit can be chemically bonded with the amorphous resin unit. Alternatively, when forming crystalline polyester resin units, a compound may be used that is reactive with polyhydric alcohols or polyhydric carboxylic acids and has a site that is reactive with amorphous resin units. By using the above method, a hybrid resin can be formed in which an amorphous resin unit is molecularly bonded to a crystalline polyester resin unit (graft structure).

[0202] (2) A method for producing a hybrid resin by forming crystalline polyester resin units and amorphous resin units separately and then combining them. In this method, a crystalline polyester resin unit is first formed by a condensation reaction between a polycarboxylic acid and a polyhydric alcohol. In addition, separate from the reaction system that forms the crystalline polyester resin unit, the monomers constituting the amorphous resin unit described above are added and polymerized to form the amorphous resin unit. In this case, it is preferable to incorporate a portion in which the crystalline polyester resin unit and the amorphous resin unit can react with each other. The method for incorporating such reactive sites is as described above, so a detailed explanation will be omitted. Next, the crystalline polyester unit formed above is reacted with the amorphous resin unit. This allows for the formation of a hybrid resin in which the crystalline polyester resin unit and the amorphous resin unit are molecularly bonded together. Furthermore, if the above-mentioned reactive sites are not incorporated into the crystalline polyester resin unit and the amorphous resin unit, a system in which the crystalline polyester resin unit and the amorphous resin unit coexist may be formed. A compound having sites that can bond with the crystalline polyester resin unit and the amorphous resin unit may then be introduced into this system. Furthermore, a hybrid resin can be formed in which crystalline polyester resin units and amorphous resin units are molecularly bonded together via the compound.

[0203] (3) A method for producing a hybrid resin by forming crystalline polyester resin units in advance and carrying out a polymerization reaction in which amorphous resin units are formed in the presence of the crystalline polyester resin units. In this method, a crystalline polyester resin unit is first formed by polymerizing a polycarboxylic acid and a polyhydric alcohol through a condensation reaction. Next, monomers constituting the amorphous resin unit are polymerized in the presence of the crystalline polyester resin unit to form the amorphous resin unit. In this case, as in (1) above, it is preferable to incorporate into the crystalline polyester resin unit or amorphous resin unit parts that are capable of reacting with each other. The method for incorporating such reactive sites is as described above, so a detailed explanation will be omitted.

[0204] By using the above method, a hybrid resin can be formed in which amorphous resin units are molecularly bonded to crystalline polyester resin units (graft structure). Among the formation methods (1) to (3) described above, method (1) is preferred. Method (1) facilitates the formation of a hybrid resin with a structure in which crystalline polyester resin chains are grafted onto amorphous resin chains, and simplifies the production process. Furthermore, method (1) involves forming amorphous resin units beforehand and then bonding crystalline polyester resin units to them. Therefore, the orientation of the crystalline polyester resin units tends to be more uniform. Therefore, it is preferable because it is possible to reliably form a hybrid resin suitable for the toner specified in the present invention.

[0205] <Coloring agent> As colorants that can constitute toner matrix particles, carbon black, magnetic materials, dyes, pigments, etc., can be used as desired. Examples of carbon black include channel black, furnace black, acetylene black, thermal black, and lamp black. As magnetic materials, ferromagnetic metals such as iron, nickel, and cobalt, alloys containing these metals, compounds of ferromagnetic metals such as ferrite and magnetite, alloys that do not contain ferromagnetic metals but exhibit ferromagnetism upon heat treatment, such as Heusler alloys like manganese-copper-aluminum and manganese-copper-tin, and chromium dioxide can be used.

[0206] Examples of colorants for magenta or red include CI Pigment Red 2, 3, 5, 6, 7, 15, 16, 48:1, 48:3, 53:1, 57:1, 60, 63, 64, 68, 81, 81:4, 83, 87, 88, 89, 90, 112, 114, 122, 123, 139, 144, 149, 150, 163, 166, 170, 177, 178, 184, 202, 206, 207, 209, 222, 238, and 269.

[0207] In addition, examples of colorants for orange or yellow include CI Pigment Orange 31, 43, CI Pigment Yellow 12, 14, 15, 17, 74, 83, 93, 94, 138, 139, 155, 162, 180, 185, and CI Solvent Yellow 93.

[0208] Furthermore, examples of colorants for green or cyan include CI Pigment Blue 2, 3, 15, 15:2, 15:3, 15:4, 16, 17, 60, 62, 66, and CI Pigment Green 7.

[0209] These colorants can be used individually or in combination of two or more as needed. The amount of colorant added is preferably in the range of 1 to 30% by mass relative to the total toner matrix particles. More preferably, it is in the range of 2 to 20% by mass, and mixtures of these can also be used. Within this range, color reproduction accuracy of the image can be ensured. Furthermore, the dispersion diameter of the colorant in the toner is preferably in the range of 10 to 1000 nm and 50 to 500 nm in terms of volume-average particle size. Moreover, the range of 80 to 300 nm is particularly preferred.

[0210] <Release agent> The release agent that constitutes the toner matrix particles is not particularly limited, and any known release agent can be used. Specifically, examples include polyolefin waxes such as polyethylene wax and polypropylene wax; branched hydrocarbon waxes such as microcrystalline wax; long-chain hydrocarbon waxes such as paraffin wax and sazole wax; dialkylketone waxes such as distearyl ketone; carnauba wax, montane wax; behenate behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, ester waxes such as tristearyl trimellitate and distearyl maleate; and amide waxes such as ethylenediamine behenylamide and tristearyl trimellitate.

[0211] The melting point of the release agent is preferably in the range of 40 to 160°C, and more preferably in the range of 50 to 120°C. By keeping the melting point within the above range, the heat resistance and storage properties of the toner are ensured. Furthermore, even when fixing at low temperatures, stable toner image formation can be achieved without causing cold offset or other problems. The release agent content in the toner matrix particles is preferably in the range of 1 to 30% by mass, and more preferably in the range of 5 to 20% by mass.

[0212] <Charge control agent> A charge control agent may be added to the toner matrix particles according to the present invention as needed. Various known charge control agents can be used.

[0213] Various known compounds that can be dispersed in an aqueous medium can be used as charge control agents. Specifically, these include nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, salicylic acid metal salts or their metal complexes.

[0214] The content of the charge control agent is preferably in the range of 0.1 to 10% by mass relative to the total amount of the binder resin, and more preferably in the range of 0.5 to 5% by mass.

[0215] <External additives> The toner particles constituting the electrostatic image developing toner according to the present invention contain at least a lubricant as an external additive. External additives can improve the electrostatic properties, fluidity, or cleaning ability of the toner. Examples of external additives include, in addition to the lubricant, known inorganic fine particles and organic fine particles.

[0216] The lubricant is used to further improve cleaning and transfer properties, and is particularly used to obtain the effects of the present invention. Examples of lubricants include metal salts of higher fatty acids, such as zinc, aluminum, copper, magnesium, and calcium salts of stearate; zinc, manganese, iron, copper, and magnesium salts of oleate; zinc, copper, magnesium, and calcium salts of palmitate; zinc and calcium salts of linoleate; and zinc and calcium salts of ricinoleate.

[0217] From the viewpoint of improving surface lubricity, it is preferable that the fatty acid metal salt is zinc stearate. Zinc stearate has moderate negative charge properties and moderate affinity for electron-accepting resins. Furthermore, the spacing between the layered crystals, determined by the alkyl chain length, becomes appropriate, resulting in good cleavage and ductility, which further improves surface lubricity.

[0218] It is preferable that the amount of the fatty acid metal salt added is within the range of 0.25 to 0.35% by mass relative to 100% by mass of toner matrix particles. If the amount of fatty acid metal salt added is within the range of 0.25 to 0.35% by mass relative to 100% by mass of toner matrix particles, the spreading effect will be sufficient, but the coating rate of the fatty acid metal salt will not decrease, and the surface lubricity can be sufficiently improved.

[0219] Furthermore, it is preferable that the average particle size of the lubricant used in the present invention is within the range of 1 to 5 μm, as this can reliably prevent toner filming from occurring.

[0220] If the particle size of the fatty acid metal salt is small, it can be applied more uniformly, improving the lubricity of the surface. From the above viewpoint, the particle size is preferably 4 μm or less, and more preferably 2 μm or less.

[0221] Preferred inorganic fine particles include those made of silica, titania, alumina, and strontium titanate. In particular, it is preferable to use alumina particles as inorganic fine particles. This is because the external additive that separates from the toner particles accumulates between the edge of the cleaning blade and the photoreceptor, polishing the photoreceptor. Here, the inclusion of high-hardness alumina particles in the external additive allows for uniform abrasion of the photoreceptor resin and metal oxide particles, which have different hardness levels. As a result, stable cleaning performance can be achieved throughout the entire process. Furthermore, from the viewpoint of stress resistance, large-particle silica with a number-average primary particle size in the range of 80 to 500 nm may be added. Furthermore, these inorganic microparticles may be hydrophobized if necessary. The amount of alumina particles added is preferably in the range of 0.4 to 0.6% by mass relative to 100% by mass of toner matrix particles, in terms of toner charge stability and proper polishing of the photoreceptor.

[0222] As organic microparticles, spherical organic microparticles with a number-average primary particle size in the range of approximately 10 to 2000 nm can be used. Specifically, organic microparticles made from homopolymers such as styrene and methyl methacrylate, or copolymers thereof, can be used.

[0223] These external additives may be used in various combinations. The total amount of external additives added is preferably in the range of 0.1 to 10.0% by mass relative to 100% by mass of toner matrix particles.

[0224] [Image forming apparatus] The image forming apparatus used in the electrophotographic image forming system of the present invention is preferably an image forming apparatus that uses a general electrophotographic method. The image forming apparatus preferably comprises at least an electrophotographic photoreceptor, a charging means, an exposure means, a developing means, a transfer means, a fixing means, and a cleaning means. The cleaning means is comprised of a cleaning blade with an obtuse edge angle. The cleaning means may also include a brush (brush roller) provided upstream of the cleaning blade that contacts the surface of the photoreceptor. The image forming apparatus according to the present invention is preferably a tandem type image forming apparatus.

[0225] Figure 2 is an explanatory cross-sectional view showing an example of the configuration of the image forming apparatus of the present invention, and Figure 3 is an explanatory cross-sectional view showing an example of the configuration of the main part of the image forming apparatus. As shown in Figure 2, the image forming apparatus 100 is referred to as a tandem-type color image forming apparatus. The image forming apparatus 100 has four sets of image forming units 110Y, 110M, 110C, and 110Bk, a paper feeding and transporting means 150, and a fixing means 170. A document image reading device SC is located on the upper part of the main body of the image forming apparatus 100.

[0226] The image forming units 110Y, 110M, 110C, and 110Bk are arranged in a vertical line. The image forming units 110Y, 110M, 110C, and 110Bk each include a rotating drum-shaped photoreceptor 111Y, 111M, 111C, and 111Bk, a lubricant supply means sequentially arranged along the rotation direction of the photoreceptor in the outer peripheral surface region, a charging means 113Y, 113M, 113C, and 113Bk, an exposure means 115Y, 115M, 115C, and 115Bk, a developing means 117Y, 117M, 117C, and 117Bk, a primary transfer roller (primary transfer means) 133Y, 133M, 133C, and 133Bk, a cleaning means 119Y, 119M, 119C, and 119Bk, and a lubricant removal means. The device is configured such that yellow (Y), magenta (M), cyan (C), and black (Bk) toner images are formed on the photoreceptors 111Y, 111M, 111C, and 111Bk, respectively.

[0227] The image forming units 110Y, 110M, 110C, and 110Bk are configured similarly except for the difference in the color of the toner image formed on the photoreceptors 111Y, 111M, 111C, and 111Bk. The following explanation will use the image forming unit 110Y as an example. Furthermore, the following will describe the electrophotographic photoreceptor, charging means, exposure means, developing means, transfer means, fixing means, and cleaning means in that order.

[0228] <Means of charging> As shown in Figure 3, the charging means 113Y is a means of charging the surface of the photoreceptor 111Y using a charging roller. In this example, the charging means 113Y consists of a charging roller disposed in contact with the surface of the photoreceptor 111Y and a power supply that applies a voltage to the charging roller.

[0229] In the present invention, the charging means is a proximity charging method in which a charging roller is in contact with or in close proximity to the surface of the photoreceptor.

[0230] As shown in Figure 4, the charging roller 11 is made up of a core metal 11a, an elastic layer 11b, a resistance control layer 11c, and a surface layer 11d, all of which are laminated together. The charging roller 11 is biased in the direction of the photoreceptor 111Y by a pressure spring 11e and is pressed against the surface of the photoreceptor 111Y with a predetermined pressure. This creates a charged nip portion, which rotates in accordance with the rotation of the photoreceptor 11Y. The elastic layer 11b is provided to reduce static electricity and to impart elasticity to obtain uniform adhesion to the photoreceptor 111Y. The resistance control layer 11c may be laminated on the surface of the elastic layer 11b as needed. By providing the resistance control layer 11c, the charging roller 11 as a whole can obtain high uniformity in electrical resistance.

[0231] The core metal 11a is made of a metal such as iron, copper, stainless steel, aluminum, and nickel, or a metal whose surface has been plated. Its outer diameter is, for example, within the range of 3 to 20 mm. Furthermore, the plating process is carried out to the extent that it does not impair conductivity in order to obtain rust prevention and scratch resistance.

[0232] The elastic layer 11b is made of an elastic material such as rubber to which conductive fine particles made of carbon black, carbon graphite, alkali metal salts, ammonium salts, etc., are added. Specific examples of elastic materials include natural rubber, synthetic rubbers such as ethylene propylene diene methylene rubber (EPDM), styrene-butadiene rubber (SBR), silicone rubber, urethane rubber, epichlorohydrin rubber, isoprene rubber (IR), butadiene rubber (BR), nitrile-butadiene rubber (NBR), and chloroprene rubber (CR), as well as resins such as polyamide resins, polyurethane resins, silicone resins, and fluororesins, or foams such as foamed sponges. The degree of elasticity can be adjusted by adding process oils, plasticizers, etc., to the elastic material.

[0233] The elastic layer 11b has a volume resistivity of 1 × 10⁻⁶ 1 ~1 × 10 10 It is preferable that the value be within the range of Ω·cm. Furthermore, the layer thickness is preferably in the range of 500 to 5000 μm, and more preferably in the range of 500 to 3000 μm. The volume resistivity of elastic layer 11b is a value measured in accordance with JIS K 6911.

[0234] The resistance control layer 11c is provided for purposes such as ensuring that the charging roller 11 as a whole has uniform electrical resistance, but it is not required. This resistance control layer 11c can be provided by coating it with a material having appropriate conductivity or by covering it with a tube having appropriate conductivity.

[0235] Specific materials that constitute this resistance control layer 11c include conductive fine particles made of carbon black, carbon graphite, etc., conductive metal oxide fine particles made of conductive titanium oxide, conductive zinc oxide, conductive tin oxide, etc., and conductive fine particles made of alkali metal salts, ammonium salts, etc., to which conductive agents are added, as described later, to a base material such as resin or rubber. Examples of resins used in the basic material include polyamide resins, polyurethane resins, fluororesins, and silicone resins. Examples of rubbers used in the aforementioned basic material include epichlorohydrin rubber, urethane rubber, chloroprene rubber, and acrylonitrile-based rubber.

[0236] The resistivity of the resistivity control layer 11c is 1 × 10⁻⁶ -2 ~1 × 10 14 It is preferably within the range of Ω·cm, and more preferably 1 × 10⁻⁶. 1 ~1 × 10 10 It is within the range of Ω·cm. Furthermore, the layer thickness is preferably in the range of 0.5 to 100 μm, more preferably in the range of 1 to 50 μm, and even more preferably in the range of 1 to 20 μm. The volume resistivity of the resistance control layer 11c is a value measured in accordance with JIS K 6911.

[0237] The surface layer 11d is provided for purposes such as preventing bleed-out of plasticizers and other substances from the elastic layer 11b onto the surface of the charging roller, obtaining slipperiness and smoothness on the surface of the charging roller, or preventing leakage even if there are defects such as pinholes on the photoreceptor 111Y. The surface layer 11d is provided by coating it with a material having appropriate conductivity or by covering it with a tube having appropriate conductivity.

[0238] When the surface layer 11d is provided by coating a material, specific materials include a base material such as resin or rubber described later, to which conductive agents such as conductive fine particles made of carbon black or carbon graphite, or conductive metal oxide fine particles made of conductive titanium oxide, conductive zinc oxide, conductive tin oxide, etc., are added. Examples of resins used in the basic material include polyamide resins, polyurethane resins, acrylic resins, fluororesins, and silicone resins. Examples of rubber used in the aforementioned base material include epichlorohydrin rubber, urethane rubber, chloroprene rubber, and acrylonitrile-based rubber. Surface coating methods include dipping, roll coating, and spray coating.

[0239] Furthermore, when the surface layer 11d is provided by covering it with a tube, specific examples of tubes include those made of nylon 12, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA), polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP); and thermoplastic elastomers such as polystyrene, polyolefin, polyvinyl chloride, polyurethane, polyester, and polyamide, to which the above-mentioned conductive agent has been added and molded into a tube shape. This tube may be heat-shrinkable or non-heat-shrinkable.

[0240] The surface layer 11d has a volume resistivity of 1 × 10⁻⁶ 1 ~1 × 10 8 It is preferably within the range of Ω·cm, and more preferably 1 × 10⁻⁶. 1 ~1 × 10 5 It is Ω·cm. Furthermore, the layer thickness is preferably in the range of 0.5 to 100 μm, more preferably in the range of 1 to 50 μm, and even more preferably in the range of 1 to 20 μm. The volume resistivity of the surface layer 11d is a value measured in accordance with JIS K 6911.

[0241] Furthermore, the surface layer 11d preferably has a surface roughness Rz in the range of 1 to 30 μm, more preferably in the range of 2 to 20 μm, and even more preferably in the range of 5 to 10 μm.

[0242] In the charging roller 11 described above, a charging bias voltage is applied to the core metal 11a of the charging roller 11 from the power supply S1. As a result, the surface of the photoreceptor 111Y is charged to a predetermined potential with a predetermined polarity. Here, the charging bias voltage may be, for example, only a DC voltage, but it is preferable to use an oscillating voltage in which an AC voltage is superimposed on a DC voltage because it provides excellent uniformity of charging. The charging bias voltage can be set to a range of approximately -2.5 to -1.5 kV, for example.

[0243] Figure 4 shows an example of the charging conditions using the charging roller. The DC voltage forming the charging bias voltage is -500V, and the AC voltage is a sine wave with a frequency of 1000Hz and a peak voltage of 1300V. When this charging bias voltage is applied, the surface of the photoreceptor is uniformly charged to -500V.

[0244] <Exposure method> As shown in Figure 2, the exposure means 115Y exposes the surface of the photoreceptor 111Y, which is given a uniform potential by the charging means 113Y, based on an image signal (yellow image signal). This means forms an electrostatic latent image corresponding to the yellow image. The exposure means 115Y is composed of an LED with light-emitting elements arranged in an array along the axial direction of the photoreceptor 111Y and an imaging element, or a laser optical system is used.

[0245] <Developing method> As shown in Figure 2, the developing means (developer) 117Y is a means for supplying toner to the surface of the photoreceptor 111Y, developing the electrostatic latent image formed on the surface of the photoreceptor 111Y, and forming a toner image. In this example, the developing means 117Y consists of a developing roller 118Y and a voltage application device (not shown) that applies a DC and / or AC bias voltage between the photoreceptor 111Y and the developing roller 118Y. The 118Y developing roller has a built-in magnet that holds the developing agent and allows it to rotate. It is preferable to position the developing means 117Y at the downstream position in the rotational direction of the photoreceptor, as this makes it easier for toner filming to occur at the downstream position.

[0246] The rotation of the developing roller 118Y transports toner to the photoreceptor 111Y. Then, the thin layer of toner on the developing roller 118Y comes into contact with the photoreceptor 111Y and develops the electrostatic latent image on the photoreceptor 111Y. The developing roller 118Y is connected to a voltage application device. Then, this voltage application device applies a DC and / or AC bias voltage to the developing roller 118Y. The system is configured to allow the development potential (also called development bias) (Vdc) to be adjusted to a desired value by controlling the voltage applied to the developing roller 118Y. An electric field is formed in the developing section by the potential difference (developing potential difference) between the potential of the electrostatic latent image supported by the developing roller 118Y and the photoreceptor 111Y. The developing section is the part where the developing roller 118Y and the photoreceptor 111Y face each other.

[0247] The toner in the developer, transported to the developing section by the rotation of the developing roller 118Y, moves due to the force from the electric field and adheres to the electrostatic latent image on the photoreceptor 111Y. As the electrostatic latent image carried on the photoreceptor 111Y is made visible, a toner image corresponding to the shape of the electrostatic latent image is formed on the surface of the photoreceptor 111Y.

[0248] Here, the electrostatic latent image on the photoreceptor includes a non-image area and an image area. The non-image area is the portion of the surface of the photoreceptor 111Y that is uniformly charged by the charging roller 113Y, and the non-image area potential (V0) is the potential of this non-image area. The image area is the portion of the surface of the photoreceptor 111Y where the non-image area is exposed by the exposure means, causing its potential to decrease. The image area potential (Vi) is the potential of this image area. Furthermore, the development potential (Vdc) is set to a value between the non-image potential (V0) and the image potential (Vi). In the non-image area, an electric field is formed that moves the toner from the photoreceptor toward the developing means. In the image area, an electric field is formed that moves the toner from the developing means towards the photoreceptor.

[0249] In this invention, the developing conditions of a developing machine under normal temperature and humidity conditions of 23°C and 50%RH are set to any of the above conditions (i) to (iii) compared to conditions under normal temperature and humidity conditions of 10°C and 20%RH. (i) Reduce the AC duty cycle of the developing potential applied to the developing roller of the developing machine (the ratio of the negative side of the AC current (time) T(-) to the period T). (ii) Reduce the concentration of the toner for the two-component developer in the two-component developer. (iii) Increase the flick margin (non-image potential V0 of the photoreceptor - development potential Vdc).

[0250] Therefore, for example, when setting condition (i), the voltage application device of the developing means applies a voltage to the developing roller such that the AC duty cycle of the AC and DC superimposed on it is reduced. Furthermore, if condition (iii) is set, the Vc applied to the core of the electrostatic roller will be Set the absolute value to a high value. Furthermore, when setting condition (ii), the two-component developer used should be a developer with a low toner concentration.

[0251] <Transfer method> As shown in Figure 2, the primary transfer roller 133Y, which constitutes the transfer means, is a means for transferring the toner image formed on the photoreceptor 111Y to an endless belt-shaped intermediate transfer body 131. The primary transfer roller 133Y is positioned in contact with the intermediate transfer body 131.

[0252] In this image forming apparatus 100, an intermediate transfer method is employed, but the apparatus is not limited to this, and a direct transfer method may also be employed. Here, the intermediate transfer method is a method in which toner images formed on photoreceptors 111Y, 111M, 111C, and 111Bk are transferred to an intermediate transfer body 131 by primary transfer rollers (primary transfer means) 133Y, 133M, 133C, and 133Bk. Subsequently, each toner image transferred on the intermediate transfer body 131 is transferred to a transfer material P by a secondary transfer roller (secondary transfer means) 217. The direct transfer method is a method in which a toner image formed on a photoreceptor is directly transferred to a transfer material using a transfer means.

[0253] <Cleaning Methods> As shown in Figure 3, the cleaning means 119Y is a means for removing toner remaining on the surface of the photoreceptor 111Y. In this example, the cleaning means 119Y consists of at least a cleaning blade. As described above, the cleaning blade according to the present invention, which is used as the cleaning means described above, will be explained here in conjunction with Figures 2 and 3. This cleaning blade consists of a support member and a blade member supported on the support member via an adhesive layer (not shown). The blade member is positioned such that its tip faces in the opposite direction (counter direction) to the direction of rotation of the photoreceptor 111Y at the point of contact with the surface of the photoreceptor 111Y.

[0254] The support members are not particularly limited, and conventionally known members can be used. Examples include those made from rigid metals, elastic metals, plastics, ceramics, etc. Among these, rigid metals are preferred.

[0255] The blade component is preferably made of polyurethane. Examples of polyurethanes include those obtained by reacting polyols, polyisocyanates, and, if necessary, crosslinking agents. It may have a single-layer structure, or it may have a multilayer structure in which a base layer and an edge layer are stacked.

[0256] Furthermore, it is preferable that the cleaning means 119Y includes a brush in addition to the cleaning blade. The brush has the function of removing residual toner adhering to the photoreceptor, recovering residual toner removed by the cleaning blade, and rubbing the surface of the photoreceptor. In other words, the brush comes into contact with the surface of the photoreceptor. At the contact point, the brush rotates in the same direction as the photoreceptor, removing residual toner and paper dust from the photoreceptor, and transporting and recovering residual toner removed by the cleaning blade.

[0257] The brush is formed on the circumferential surface of a roller base, and consists of a long woven fabric in which resin brush fibers, such as polypropylene, are densely implanted. The brush roller has brush fibers with thicknesses of, for example, 3-7 denier, a length of 2-5 mm, and an electrical resistivity of 1 x 10⁻¹⁰. 10It is preferable that the Young's modulus is Ω or less. Also, the Young's modulus of the brush fibers should be 1500 to 9800 N / mm². 2 The density of brush fibers (number of brush fibers per unit area) is 50k~200kF / inch 2 It is preferable that this be the case.

[0258] As shown in Figure 2, the intermediate transfer body 131 is wound around and rotatably supported by a plurality of rollers 137A, 137B, 137C, and 137D. A cleaning means 135 for removing toner remaining on the intermediate transfer body 131 is provided on the intermediate transfer body 131.

[0259] In this image forming apparatus 100, the photoreceptor 111Y, developing means 117Y, cleaning means 119Y, etc., may be integrally combined into a process cartridge. Preferably, the process cartridge (image forming unit) is configured to be detachably attached to the main body of the apparatus. Alternatively, it may be a process cartridge (image forming unit) in which one or more components selected from the group consisting of a charging means 113Y, an exposure means 115Y, a developing means 117Y, a primary transfer roller 133Y, and a cleaning means 119Y are integrally configured with a photoreceptor 111Y.

[0260] The process cartridge 200 comprises a housing 201, a photoreceptor 111Y housed therein, a charging means 113Y, a developing means 117Y, a cleaning means 119Y, and a primary transfer roller 133Y. Furthermore, the device body is provided with support rails 203L and 203R as means for guiding the process cartridge 200 into the device body. This allows the process cartridge 200 to be attached to and detached from the main unit of the device. These process cartridges 200 can form a single image forming unit that is detachably configured to attach to the main body of the device.

[0261] The paper feeding and transport means 150 is configured to transport the transfer material P in the paper feeding cassette 211 to the secondary transfer roller 217 via a plurality of intermediate rollers 213A, 213B, 213C, 213D and a registration roller 215.

[0262] The fixing means 170 fixes the color image transferred by the secondary transfer roller 217. The paper output roller 219 is provided to hold the fixed transfer material P and place it on the paper output tray 221.

[0263] In the image forming apparatus 100 configured in this way, toner images are formed by image forming units 110Y, 110M, 110C, and 110Bk. Specifically, first, the charging means 113Y, 113M, 113C, and 113Bk discharge electricity onto the surface of the photoreceptors 111Y, 111M, 111C, and 111Bk, causing them to become negatively charged. Next, the exposure means 115Y, 115M, 115C, and 115Bk expose the surfaces of the photoreceptors 111Y, 111M, 111C, and 111Bk based on the image signal to form an electrostatic latent image. Next, the developing means 117Y, 117M, 117C, and 117Bk apply toner to the surface of the photoreceptors 111Y, 111M, 111C, and 111Bk to develop and form a toner image.

[0264] Next, the primary transfer rollers (primary transfer means) 133Y, 133M, 133C, and 133Bk are brought into contact with the rotating intermediate transfer body 131. This causes the toner images of each color, formed on the photoreceptors 111Y, 111M, 111C, and 111Bk respectively, to be sequentially transferred onto the rotating intermediate transfer unit 131. Then, the color image is transferred (primary transfer). During the image formation process, the primary transfer roller 133Bk is constantly in contact with the photoreceptor 111Bk. On the other hand, the other primary transfer rollers 133Y, 133M, and 133C come into contact with the corresponding photoreceptors 111Y, 111M, and 111C, respectively, only when a color image is being formed.

[0265] Then, the primary transfer rollers 133Y, 133M, 133C, and 133Bk are separated from the intermediate transfer body 131. After that, the toner remaining on the surface of the photoreceptors 111Y, 111M, 111C, and 111Bk is removed by the cleaning means 119Y, 119M, 119C, and 119Bk. Next, the surfaces of the photoreceptors 111Y, 111M, 111C, and 111Bk are discharged using a static discharge means (not shown) as needed. Subsequently, they are negatively charged using charging means 113Y, 113M, 113C, and 113Bk.

[0266] Meanwhile, the transfer material P (a support that carries the final image, such as plain paper or a transparent sheet) contained in the paper feed cassette 211 is fed by the paper feed transport means 150. It is then transported to the secondary transfer roller (secondary transfer means) 217 ​​via a plurality of intermediate rollers 213A, 213B, 213C, 213D and a registration roller 215. Then, the secondary transfer roller 217 is brought into contact with the rotating intermediate transfer body 131, and the color image is transferred onto the transfer material P all at once (secondary transfer). The secondary transfer roller 217 comes into contact with the intermediate transfer body 131 only when performing a secondary transfer onto the transfer material P. Subsequently, the transfer material P, on which the color image has been transferred in one piece, is separated at the part of the intermediate transfer body 131 with high curvature.

[0267] The transfer material P, on which the color image has been transferred in this manner, is then fixed by the fixing means 170. After that, it is held in place by the paper output roller 219 and placed on the paper output tray 221 outside the device. Furthermore, after separating the transfer material P on which the color image has been transferred in one go from the intermediate transfer body 131, the cleaning means 135 removes any remaining toner from the intermediate transfer body 131. [Examples]

[0268] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these. In the following examples, unless otherwise specified, the operations were carried out at room temperature (25°C). Unless otherwise specified, "%" and "parts" mean "mass%" and "parts by mass," respectively.

[0269] 1. Fabrication of an electrophotographic photoreceptor 1-1. Preparation of Photoreceptor 1 A photoreceptor 1 was fabricated by following the procedure below, in which an intermediate layer, a charge generation layer, a charge transport layer, and a protective layer were laminated in that order on a conductive support.

[0270] <Conductive support> A cylindrical aluminum support with a diameter of 30 mm was machined to create a conductive support with a surface roughness of Rz = 1.5 (μm).

[0271] <Middle class> A sand mill was used as a disperser to perform a batch dispersion treatment on the mixture of the following components for 10 hours. After that, the mixture was diluted twice with methanol, allowed to stand overnight, and then filtered using a 5 μm RigiMesh filter manufactured by Nippon Pall Co., Ltd. to obtain the intermediate layer coating solution. Polyamide resin (manufactured by Toray Industries, Inc., Amiran CM8000 (Amiran is a registered trademark of the company)) 1 part by mass Titanium oxide (manufactured by Teika Co., Ltd., SMT500SAS) 3 parts by mass 10 parts by mass of methanol The above-mentioned intermediate layer coating solution was applied to the surface of the conductive support by immersion coating to a dry film thickness of 2 μm, and then dried to obtain the intermediate layer.

[0272] <Charge generation layer> A sand mill was used as a disperser to disperse a mixture of the following components for 10 hours to obtain a charge generation layer coating solution. Charge-generating material: Titanyl phthalocyanine pigment (titanium phthalocyanine pigment having the maximum diffraction peak at at least 27.3° in Cu-Kα characteristic X-ray diffraction spectrum measurement) 20 parts by mass Polyvinyl butyral resin (manufactured by Denki Kagaku Kogyo Co., Ltd., #6000-C) 10 parts by mass 700 parts by mass of t-butyl acetate 4-Methoxy-4-methyl-2-pentanone 300 parts by mass The above charge generation layer coating solution was applied to the surface of the intermediate layer by immersion coating to a dry film thickness of 0.3 μm, and then dried to obtain the charge generation layer.

[0273] <Charge transport layer> The following components were stirred and mixed to obtain a charge transport layer coating solution. Charge transport material (CTM-A) 225 parts by mass Polycarbonate resin (manufactured by Mitsubishi Gas Chemical Company, Inc., Z300) 300 parts by mass Antioxidant (BASF, Irganox 1010) 6 parts by mass 1600 parts by mass of tetrahydrofuran Toluene 400 parts by mass Silicone oil (manufactured by Shin-Etsu Chemical Co., Ltd., KF-54) 1 part by mass The above transport generation layer coating solution was applied to the surface of the charge generation layer by immersion coating to a dry film thickness of 20 μm, and then dried to obtain a charge transport layer.

[0274] <Protective layer> The following components were stirred and mixed to obtain protective layer coating solution 1. ·Resin composition SR350: Trimethylolpropane trimethacrylate (manufactured by Sartomer, SR350) 30 parts by mass 35 parts by mass of radical polymerizable charge transport compound A1 Metal oxide particle 1 (silicon oxide with a number-average primary particle size of 300 nm, surface-modified (surface-treated) with the same mass of methylhydrogenpolysiloxane) 50 parts by mass Metal oxide particles 2 (silicon oxide with a number-average primary particle size of 40 nm, surface-modified (surface-treated) with the same mass of methylhydrogenpolysiloxane) 20 parts by mass Polymerization initiator (Ominirad819, manufactured by IGM.Resis.BV) 5 parts by mass ·solvent Tetrahydrofuran (THF) 350 parts by mass 150 parts by mass of 2-butanol (2-BuOH)

[0275] The protective layer coating solution 1 was applied to the surface of the charge transport layer using a circular slide hopper coating machine. Then, the applied protective layer coating solution 1 was irradiated with ultraviolet light (wavelength 385 nm) from a xenon lamp for 1 minute to obtain a protective layer with a dry film thickness of 3 μm. The radically polymerizable charge transport compound A1 is as shown below.

[0276] 1-2. Preparation of photoreceptors 2-30 As shown in Tables I and II below, photoreceptors 2 to 30 were prepared in the same manner as photoreceptor 1 by appropriately changing the content and type of SR350, radical polymerizable charge transport compound, metal oxide particles, polymerization initiator, and solvent. This resulted in the formation of photoreceptors 2 to 30 with different average spacings of surface irregularities. Here, assuming that silicon dioxide has a specific gravity of 2.0, aluminum oxide has a specific gravity of 4.0, and the others have a specific gravity of 1.0, the mass parts can be calculated to achieve the target volume content. Furthermore, the average spacing of the surface irregularities of the photoreceptor can be increased by reducing the amount of solvent relative to the resin composition or by increasing the ratio of tetrahydrofuran to 2-butanol. In the table below, charge-transporting compounds (resins) A1 to E1 are the compounds shown below.

[0277] [ka]

[0278] [Table 1]

[0279] [Table 2]

[0280] 2. Preparation of electrophotographic toner <Synthesis of Hybrid Crystalline Polyester Resin (Tc1)> The raw material monomers and radical polymerization initiators for the following addition polymerization resin (styrene-acrylic resin: StAc) units, which contain both reactive monomers, were placed in a dropper funnel. 34 parts by mass of styrene n-butyl acrylate 12 parts by mass Acrylic acid 2 parts by mass Polymerization initiator: Di-t-butyl peroxide 7 parts by mass

[0281] Furthermore, the raw material monomers for the polycondensation resin (crystalline polyester resin: CPEs) units described below were placed in a four-necked flask and heated to 170°C to dissolve them. The four-necked flask used was equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple. Sebacic acid 369 parts by mass 1,10-Decanediol 318 parts by mass

[0282] Next, the raw material monomers for the addition polymerization resin (StAc) were added dropwise over 90 minutes under stirring, followed by 60 minutes of aging. After that, unreacted addition polymerization monomers were removed under reduced pressure (8 kPa). Furthermore, the amount of monomer removed at this time was very small compared to the ratio of raw material monomers in the resin mentioned above. Subsequently, 0.8 parts by mass of Ti(OBu)4 were added as an esterification catalyst, and the reaction was carried out at a temperature of 235°C and under atmospheric pressure (101.3 kPa) for 5 hours. Furthermore, the reaction was carried out under reduced pressure (8 kPa) for 1 hour.

[0283] Next, after cooling to 200°C, the mixture was reacted under reduced pressure (20 kPa) for 1 hour to obtain a hybrid crystalline polyester resin (Tc1). The hybrid crystalline polyester resin (Tc1) contained 8% by mass of resin (StAc) units other than CPEs (crystalline polyester resin) relative to its total amount, and was a resin in which CPEs were grafted onto StAc. Furthermore, the number-average molecular weight (Mn) of the hybrid crystalline polyester resin (Tc1) was 9000, and its melting point (Tm) was 76°C.

[0284] <Preparation of an aqueous dispersion (TC1) of hybrid crystalline polyester resin particles> Thirty parts by mass of the above-mentioned crystalline polyester resin were melted. While still in the molten state, it was transferred to an emulsifying and dispersing machine "Cavitron CD1010" (manufactured by Eurotech Co., Ltd.) at a transfer speed of 100 parts by mass per minute. In addition, simultaneously with the transfer of the molten crystalline polyester resin, dilute ammonia water was transferred to the emulsifying disperser "Cavitron CD1010" (manufactured by Eurotech Co., Ltd.) at a transfer rate of 0.1 liters per minute while being heated to 100°C in a heat exchanger. The dilute ammonia water was prepared by diluting 70 parts by mass of reagent ammonia water with ion-exchanged water in an aqueous solvent tank, resulting in a concentration of 0.37% by mass. Then, this emulsifying and dispersing machine, "Cavitron CD1010" (manufactured by Eurotech Co., Ltd.), was set to a rotor rotation speed of 60Hz and a pressure of 5kg / cm². 2 The system was operated under the following conditions. This resulted in the preparation of a fine particle dispersion of crystalline polyester resin with a solid content of 30 parts by mass. At this time, the particles contained in the fine particle dispersion of the crystalline polyester resin had a median diameter of 200 nm by volume.

[0285] <Preparation of aqueous dispersion of amorphous resin particles (X1)> (First stage polymerization) 8 parts by mass of sodium dodecyl sulfate and 3000 parts by mass of deionized water were charged into a 5 L reaction vessel equipped with a stirrer, temperature sensor, cooling tube, and nitrogen introduction device. The internal temperature was raised to 80°C while stirring at a stirring speed of 230 rpm under a nitrogen flow. After raising the temperature, 10 parts by mass of potassium persulfate dissolved in 200 parts by mass of deionized water was added. Then, the liquid temperature was raised again to 80°C, and a monomer mixture with the following composition was added dropwise over 1 hour. Polymerization was carried out by heating and stirring at 80°C for 2 hours to prepare a dispersion of resin fine particles (x1). Styrene 480 parts by mass n-butyl acrylate 250 parts by mass Methacrylic acid 68.0 parts by mass

[0286] (Second stage polymerization) A 5L reaction vessel equipped with a stirrer, temperature sensor, cooling tube, and nitrogen introduction device was charged with a solution prepared by dissolving 7 parts by mass of sodium polyoxyethylene(2) dodecyl ether sulfate in 3000 parts by mass of deionized water. After heating to 98°C, 260 parts by mass of a dispersion of resin fine particles (x1) and a solution prepared by dissolving monomers and a release agent with the following composition at 90°C were added. The mixture was then mixed and dispersed for 1 hour using a mechanical disperser "CLEARMIX" (manufactured by M-Technique Co., Ltd.) with a circulation path to prepare a dispersion containing emulsion particles (oil droplets). Styrene (St) 284 parts by mass n-butyl acrylate (BA) 92 parts by mass Methacrylic acid (MAA) 13 parts by mass n-octyl-3-mercaptopropionate 1.5 parts by mass Release agent: Behenate behenate (melting point 73°C) 190 parts by mass

[0287] Next, an initiator solution prepared by dissolving 6 parts by mass of potassium persulfate in 200 parts by mass of deionized water was added to this dispersion. Polymerization was carried out by heating and stirring this system at 84°C for 1 hour to prepare a dispersion of resin fine particles (x2).

[0288] (Third stage polymerization) Furthermore, 400 parts by mass of deionized water were added to the dispersion of resin fine particles (x2) and mixed thoroughly. Then, a solution of 11 parts by mass of potassium persulfate dissolved in 400 parts by mass of deionized water was added, and a monomer mixture having the following composition was added dropwise over 1 hour under a temperature of 82°C. After the dropwise addition was complete, polymerization was carried out by heating and stirring for 2 hours, and then cooled to 28°C to prepare an aqueous dispersion of amorphous resin fine particles made of vinyl resin (X1). The obtained aqueous dispersion of amorphous resin fine particles (X1) had a volume-based median diameter of 220 nm. It also had a glass transition temperature (Tg) of 55°C and a weight-average molecular weight (Mw) of 32,000. Styrene (St) 350 parts by mass n-butyl acrylate (BA) 215 parts by mass Acrylic acid (AA) 30 parts by mass n-octyl-3-mercaptopropionate 8 parts by mass

[0289] <Preparation of an aqueous dispersion of colorant particles (Cy1)> 90 parts by mass of sodium dodecyl sulfate was added to 1600 parts by mass of deionized water. While stirring this solution, 420 parts by mass of copper phthalocyanine (CIPigment Blue 15:3) was gradually added. Then, an aqueous dispersion of colorant particles (Cy1) was prepared by dispersion treatment using a stirring device "Cleamix" (manufactured by M-Technique). For the resulting aqueous dispersion of colorant particles (Cy1), the median diameter of the colorant particles, based on volume, was 110 nm.

[0290] <Manufacturing of Cyan Toner T1> A reaction vessel equipped with a stirrer, temperature sensor, and cooling tube was prepared. 288 parts by mass (based on solid content) of an aqueous dispersion of amorphous resin fine particles (X1), 70 parts by mass (based on solid content) of an aqueous dispersion of hybrid crystalline polyester resin fine particles (TC1), and 2000 parts by mass of deionized water were added to this reaction vessel. Subsequently, a 5 mol / liter sodium hydroxide aqueous solution was added to adjust the pH to 10. Next, 30 parts by mass (on a solid content basis) of an aqueous dispersion of coloring agent particles (Cy1) was added. Furthermore, an aqueous solution prepared by dissolving 60 parts by mass of magnesium chloride in 60 parts by mass of deionized water was added over 10 minutes at 30°C under stirring. After standing for 3 minutes, the heating process was initiated, and the system was heated to 80°C over 60 minutes. The particle growth reaction was then continued while maintaining this temperature. In this state, the particle size of the associated particles was measured using a "Coulter Multisizer 3" (manufactured by Coulter-Beckman). When the volume-based median diameter reached 6.0 μm, an aqueous solution of 190 parts by mass of sodium chloride dissolved in 760 parts by mass of deionized water was added to stop particle growth. Furthermore, the temperature was increased, and the mixture was heated and stirred at 90°C. This promoted particle fusion, and when the average circularity of the toner reached 0.945 using the FPIA-2100 (Sysmex) measuring device (with 4000 HPF detections), it was cooled to 30°C at a cooling rate of 2.5°C / min.

[0291] Next, the toner cake was separated into solid and liquid components, dehydrated, and then redispersed in deionized water. This process was repeated three times for washing, and the cake was then dried at 40°C for 24 hours. This yielded toner matrix particles 1. 100 parts by mass of the obtained toner matrix particles 1 were mixed with 0.6 parts by mass of silica particles 1, 0.5 parts by mass of titania particles, 0.5 parts by mass of alumina particles, and 0.3 parts by mass of zinc stearate as a fatty acid metal salt. The mixture was then mixed using a "Henschel mixer" (manufactured by Mitsui Miike Chemical Machinery Co., Ltd.) at a rotor blade speed of 35 mm / sec and 32°C for 20 minutes, followed by an external additive treatment to remove coarse particles using a sieve with a mesh size of 45 μm. This yielded cyan toner T1 with a volume-average particle size of 6.1 μm. The number-average primary particle size of the silica particles was 12 nm, the number-average primary particle size of the titania particles was 20 nm, and the number-average primary particle size of the alumina particles was 15 nm.

[0292] <Manufacturing of Cyan Toner T2> Cyan toner T2 was obtained by manufacturing cyan toner T2 in the same manner as described above, except that the alumina particles were replaced with silica particles 2 (number average primary particle size = 20 nm).

[0293] [Manufacturing of Developers] To cyan toners T1 and T2, ferrite carriers coated with acrylic resin were added and mixed so that the toner concentration in the developer was 6.5% by mass. This produced the respective developers. The volume-average particle size of the ferrite carriers was 40 μm.

[0294] 3. Making the cleaning blade <Making rubber sheets> Using 4,4′-diphenylmethane diisocyanate, polyester polyol, and short-chain polyol as raw materials, a 2 mm thick urethane rubber sheet was produced by a known centrifugal molding method. By changing the mixing ratio, we created rubber sheets with a hardness of 72° and rebound elasticity of 11°. The above rubber hardness values ​​are those specified in JIS-A.

[0295] <Edge formation> The rubber sheet A was cut by inserting a blade at an angle of 10° to the vertical, forming an edge with an edge angle of 100°.

[0296] <Cutting and gluing the cleaning blade> Furthermore, the blade was inserted vertically to cut the material into pieces measuring 340 mm x 14.0 mm. These pieces were then heat-bonded to the sheet metal with a 4 mm overlap using a thermosetting adhesive. A cleaning blade a was fabricated with a free length of 10.0 mm and a ratio of free length L to thickness d (L / d) of 5.0.

[0297] [evaluation] In a Bizhub C650i machine (manufactured by Konica Minolta), the drum unit was disassembled, modified as appropriate, and equipped with photoreceptors 1-30, a cleaning blade with an edge angle of 100°, and brushes as needed, prepared according to the table below. In addition, the developers in the developer unit and toner bottles were replaced with the respective developers prepared as described above, and the following evaluations were performed.

[0298] <Cleaning properties (filming resistance)> Evaluation unit: Bizhub C650i (EagleZ) (manufactured by Konica Minolta) Long-term printing: 300,000 sheets of 5% chart at 23°C, 50% RH (NN environment). Low-temperature, low-humidity accelerated printing: 5000 blank charts at 10°C and 20% RH (LL environment). The two printing modes described above were evaluated, and after the test, the amount of deposits on the photoreceptor surface and the dirt on the charging roller were observed and ranked as follows.

[0299] (Criteria for ranking surface deposits on photoreceptors) AA: No deposits were observed under an optical microscope (100x magnification). (Pass) A: Observed under an optical microscope (100x magnification), but not visible to the naked eye. The longest side length of the attached material was 10-200 μm. (Pass) B: Attached material was observed visually. The longest side length of the attached material was 200 μm or more. (Fail)

[0300] (Criteria for determining the level of dirt on electrostatic rollers) AA: No stains were observed visually. (Pass) A: A slight stain was observed upon visual inspection. (Pass) B: Noticeable stains and streaky toner bleed were observed visually. (Fail)

[0301] [Table 3]

[0302] [Table 4]

[0303] [Table 5]

[0304] [Table 6]

[0305] As shown in the results above, when a lubricant is added to the toner as in the present invention, and the average spacing Rsm of the surface irregularities of the protective layer of the photoreceptor is in the range of 5 to 20 μm, and the protective layer contains metal oxide particles with a number average primary particle size in the range of 150 to 550 nm in the range of 1 to 30 volume%, it is observed that, compared to the comparative example, toner leakage and adhesion of foreign matter to the photoreceptor do not occur during long-term durable printing or low-temperature, low-humidity accelerated printing. In addition, in Tables IV and V, Examples 22 to 30 should be interpreted as reference examples. [Explanation of Symbols]

[0306] 11 Electrostatic roller 11a Core metal 11b Elastic layer 11c Resistive Control Layer 11d surface layer 11e Compression spring 100 Image forming apparatus 110Y, 110M, 110C, 110Bk Image Forming Units 10, 111Y, 111M, 111C, 111Bk Photoconductor 113Y, 113M, 113C, 113Bk Charging means, charging roller 115Y, 115M, 115C, 115Bk exposure means 117Y, 117M, 117C, 117Bk developing means 118Y, 118M, 118C, 118Bk developing rollers 119Y, 119M, 119C, 119Bk, 135 Cleaning methods 131 Intermediate Transfer 133Y, 133M, 133C, 133Bk Primary Transfer Roller (Transfer Means) 137A, 137B, 137C, 137D Rollers 150 Paper feeding and transporting means 170 Fixing means 200 Process Cartridges 201 cabinet 203R, 203L Support Rails 211 Paper feed cassette 213A, 213B, 213C, 213D Intermediate Rollers 215 Resist Roller 217 Secondary transfer roller (transfer means) 219 Paper output roller 221 Paper output tray S1 power supply P Transfer Material SC Document Image Reader C L Cleaning blade Pg sheet metal C Contact part E edge section T Toner Particles θ1 Effective contact angle θ2 rigid body contact angle θ3 wedge angle θ e Edge angle L free length d thickness

Claims

1. An electrophotographic image forming system having at least a photoreceptor, charging means, exposure means, developing means, transfer means and cleaning means, The cleaning means is a means of cleaning the photoreceptor by bringing the tip edge of a cleaning blade with an obtuse edge angle into contact with the photoreceptor, The toner has a lubricant supply means for adding a lubricant and supplying it onto the photoreceptor, The photoreceptor has at least a photosensitive layer and a protective layer on a conductive support in this order, and the protective layer is formed of a cured product of a composition containing a charge-transporting compound having polymerizable functional groups and metal oxide particles. The average spacing Rsm of the surface irregularities of the protective layer is within the range of 5 to 20 μm, and The protective layer contains metal oxide particles with a number average primary particle size in the range of 150 to 550 nm in an amount of 1 to 30 volume%, and further contains metal oxide particles with a number average primary particle size in the range of 25 to 75 nm in an amount of 5 to 15 volume%. An electrophotographic image forming system characterized by the following:

2. The toner contains alumina particles The electrophotographic image forming system according to feature 1.

3. The charge transport compound having the polymerizable functional group has a structure represented by the following general formula (1). The electrophotographic image forming system according to feature 1. 【Chemistry 1】 [In general formula (1), Ar １ and Ar ２ This shows a structure that can be independently represented by general formula (2). Ar ３ This represents a structure that can be expressed by general formula (2) or general formula (3). D is independently, -(-(CH ２ )) ｄ -(O-(CH ２ )) ｆ -) ｅ -O-CO-C(CH ３ )=CH ２ ) or -(-(CH ２ )) ｄ -(O-(CH ２ )) ｆ -) ｅ -O-CO-CH=CH ２ ) and represents a structure. d and f independently represent an integer of 0 or more and 5 or less. e represents an integer of 0 or 1. c1 to c3 independently represent integers between 0 and 2. Ar ３ However, when the structure is represented by general formula (2), the total number of D atoms in the compound is 1 or 2. ３ However, when the structure is represented by general formula (3), the total number of D atoms in the compound is 1. 【Chemistry 2】 [In general formulas (2) and (3), R １ and R ２ This independently represents a functional group or atom selected from the group consisting of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a phenyl group substituted with an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, an aralkyl group having 7 to 10 carbon atoms, and a halogen atom. However, in general formula (3), the two R ２ They may combine to form a ring structure. t independently represents an integer between 1 and 3 (inclusive).

4. The electrophotographic image forming system according to claim 1, characterized in that a brush is provided that contacts the photoreceptor after the transfer means and before the cleaning means.

5. An electrophotographic image forming method using a photoreceptor, comprising at least a charging step, an exposure step, a development step, a transfer step and a cleaning step, The cleaning step is a step of cleaning the photoreceptor by bringing the tip edge of a cleaning blade, which has an obtuse edge angle, into contact with the photoreceptor. The means for supplying the lubricant onto the photoreceptor is a method of supplying toner with a lubricant added to it. The photoreceptor has at least a photosensitive layer and a protective layer on a conductive support in this order, and the protective layer is formed of a cured product of a composition containing a charge-transporting compound having polymerizable functional groups and metal oxide particles. The average spacing Rsm of the surface irregularities of the protective layer is within the range of 5 to 20 μm, and An electrophotographic image forming method characterized by containing in the protective layer metal oxide particles having a number average primary particle size in the range of 150 to 550 nm in an amount of 1 to 30 volume%, and further containing in the protective layer metal oxide particles having a number average primary particle size in the range of 25 to 75 nm in an amount of 5 to 15 volume%,.

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