Electrophotographic Imaging System

Abstract

To provide an image forming system that can obtain a satisfactory image for a long period without causing toner filming on a surface of a photoreceptor.SOLUTION: An electrophotographic image forming system includes the steps of: forming an electrostatic latent image at least on a photoreceptor; performing development by using a toner for electrostatic charge image development; and bringing a leading end ridge part of a cleaning blade into pressure contact with a surface of the photoreceptor to remove the toner for electrostatic charge image development. A surface layer of the photoreceptor contains a thermoplastic resin having at least electron acceptability. Toner particles constituting the toner for electrostatic charge image development each contain at least a fatty acid metal salt in its surface as an external additive. A leading end ridge part of a cleaning blade having an edge angle within a range of 90-130° is brought into pressure contact with a surface of the photoreceptor, and the effective contact angle of the cleaning blade is within a range of 7-20°.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to electrophotographic imaging systems. More particularly, the present invention relates to an image forming system that can obtain good images over a long period of time without causing toner filming on the surface of a photoreceptor. [Background technology]

[0002] 2. Description of the Related Art In electrophotographic image forming apparatuses using toner for developing electrostatic images (hereinafter simply referred to as "toner"), the occurrence of toner filming due to insufficient lubrication on the surface of a photoreceptor has become a problem. Toner filming is a phenomenon in which external additives and toner components adhere to the surface of a photoreceptor as nuclei, and then the external additives and toner particles themselves adhere to the nuclei, growing into large, raindrop-like clumps. When toner filming occurs, the light exposure that forms the latent image is blocked in the affected area, causing image defects such as the area appearing as a white spot in the image. Conventionally, a known method for preventing toner filming is to externally add a lubricant (a fatty acid metal salt) to the toner base particles and supply it to the surface of the photoreceptor in order to lubricate the surface of the photoreceptor and improve cleaning performance. However, in the above method, it is difficult to ensure a sufficient amount of lubricant (coverage) from the viewpoint of various functions as a developer and fixing performance, and the effect of improving toner filming is insufficient.

[0003] Patent Document 1 proposes a method of forming the edge of a cleaning blade into an obtuse angle. Here, FIG. 1 shows the cleaning blade C L When the edge E of the cleaning blade C is not obtuse, the toner particles T may L 1 is a conceptual diagram showing the direction of the force acting from and the state of the fatty acid metal salt M. Figure 2 shows the cleaning blade C L When the edge E of the cleaning blade C is obtuse, the toner particles TL 1 is a conceptual diagram showing the direction of the force acting from and the state of the fatty acid metal salt M. Comparing Figure 1 and Figure 2, Figure 2 shows that cleaning blade C L Since the edge E of the cleaning blade has an obtuse angle, the wedge angle θ3 in the wedge-shaped portion upstream of the cleaning blade nip is small, and the force F that presses the toner particles and hard particles against the photosensitive drum surface in the vertical direction is small. N increases, improving the polishing power. However, because the above effect also makes it easier to remove fatty acid metal salts from the surface of the photoreceptor, the effect of improving toner filming is insufficient from the viewpoint of achieving both lubricity and abrasive power. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 5-19671 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention was made in consideration of the above problems and circumstances, and its problem to be solved is to provide an image forming system that can obtain good images over a long period of time without causing toner filming on the photosensitive drum surface. [Means for solving the problem]

[0006] In the process of investigating the causes of the above problems in order to solve the above problems, the present inventors discovered that the above problems can be solved by an electrophotographic image forming system characterized by using a cleaning blade in which the surface layer of a photoreceptor contains a thermoplastic resin having electron-accepting properties, the toner particles contain a fatty acid metal salt, and the edge angle is in the range of 90 to 130° and the effective contact angle is in the range of 7 to 20°, and thus arrived at the present invention. That is, the above-mentioned problems of the present invention are solved by the following means.

[0007] 1. forming an electrostatic latent image on at least a photoreceptor; developing the image using a toner for developing an electrostatic image; and removing the toner for developing the electrostatic image by pressing a ridge portion of a cleaning blade against the surface of the photosensitive member, The photoreceptor has a photosensitive layer and a surface layer on a conductive support, and the surface layer contains at least One resin selected from polyimide resin, polyimide amide resin, polyetherimide resin, polyether ether ketone resin, polysulfone resin, polyether sulfone resin, polyether sulfide resin, and polycarbonate resin A thermoplastic resin is contained, the toner particles constituting the electrostatic image developing toner contain at least a fatty acid metal salt on the surface as an external additive; An electrophotographic image forming system, characterized in that the tip ridge of a cleaning blade having an edge angle in the range of 90 to 130° is pressed against the surface of the photosensitive member, and the effective contact angle of the cleaning blade is in the range of 7 to 20°.

[0008] 2. The electrophotographic imaging system according to claim 1, wherein the edge angle is an obtuse angle of 95° or more.

[0009] 3.before fever 3. The electrophotographic image forming system according to claim 1, wherein the plastic resin is a polyimide resin containing an electron-withdrawing group.

[0010] 4. The electrophotographic imaging system according to any one of claims 1 to 3, wherein the edge angle is 110° or less.

[0011] 5. The electrophotographic image forming system according to any one of items 1 to 4, wherein the amount of the fatty acid metal salt added is within a range of 0.20 to 0.30% by mass relative to the toner base particles.

[0012] 6. The electrophotographic imaging system according to any one of items 1 to 5, wherein the fatty acid metal salt is zinc stearate. [Effects of the Invention]

[0013] According to the above-described means of the present invention, it is possible to provide an image forming system that can obtain good images for a long period of time without causing toner filming on the surface of the photoreceptor.

[0014] The mechanism by which the effects of the present invention are manifested or the mechanism of action is not clear, but is speculated as follows. In the present invention, toner base particles contain a fatty acid metal salt as an external additive, and a cleaning blade with a blunted edge is used in combination with a photoreceptor containing a thermoplastic resin having electron-accepting properties in its surface layer, to form an electrophotographic image forming system.

[0015] FIG. 3 shows the toner particles T in the present invention. L 1 is a conceptual diagram showing the direction of force F acting from and the state of fatty acid metal salt M. In the present invention, the fatty acid metal salt (lubricant) is used in combination with a resin having electron-accepting properties, resulting in increased affinity and making it easier for the lubricant to be fixed to the photoreceptor. Although the reason for this is unclear, it is presumed that the fatty acid metal salt M is generally known to have positive charging properties, and the alkyl terminal portion of the fatty acid, which forms the crystal cleavage plane, has electron-donating properties, resulting in increased affinity.

[0016] As a result of the above, the edge angle θ e Cleaning blade C having an obtuse angle shape in the above range L In the wedge-shaped portion upstream of the blade nip, the force F that presses the toner particles T against the photoreceptor 10 in the vertical direction is used. N Even under high abrasive conditions, the lubricant is difficult to remove due to the toner and hard particles, and is more likely to penetrate into the blade nip.

[0017] If the fatty acid metal salt reaches the vicinity of the blade nip without being removed by the wedge-shaped portion, the obtuse shape of the blade edge reduces the wedge angle θ3, and so it is subjected to a shearing action that cleaves and spreads the layered crystals of the fatty acid metal salt, making it more likely to be fixed on the photoreceptor.

[0018] The above synergistic effect can also significantly improve the lubricity of the photoreceptor surface, thereby suppressing toner filming. [Brief explanation of the drawings]

[0019] [Figure 1] A conceptual diagram showing the direction of the force that the cleaning blade exerts on the toner particles and the state of the fatty acid metal salt when the edge of the cleaning blade is not obtuse. [Figure 2] A conceptual diagram showing the direction of the force that the cleaning blade exerts on the toner particles and the state of the fatty acid metal salt when the edge of the cleaning blade is obtuse-angled. [Figure 3] A conceptual diagram showing the direction of the force that the toner particles receive from the cleaning blade and the state of the fatty acid metal salt in the present invention. [Figure 4] Schematic diagram of the optical absorption spectrum observed in a mixture of an electron donor (reference substance) and a thermoplastic resin [Figure 5] A conceptual side view of the relationship between the cleaning blade and the electrophotographic photosensitive member according to the present invention. [Figure 6] FIG. 1 is a cross-sectional view illustrating an example of the configuration of an image forming apparatus according to the present invention. [Figure 7] FIG. 1 is a cross-sectional view illustrating an example of the configuration of a main part of an image forming apparatus. [Figure 8] 1 is a schematic diagram showing an example of the configuration of a charging unit of an image forming apparatus used in the present invention; [Figure 9] Conceptual diagram of counting the number of toner filming occurrences DETAILED DESCRIPTION OF THE INVENTION

[0020] The electrophotographic image forming system of the present invention comprises at least the steps of forming an electrostatic latent image on a photoreceptor, developing the image using a toner for developing an electrostatic image, and removing the toner for developing an electrostatic image by pressing a ridgeline of a cleaning blade against the surface of the photoreceptor, wherein the photoreceptor has a photosensitive layer and a surface layer on a conductive support, the surface layer contains a thermoplastic resin having a LUMO level lower than 1.4 eV, the toner particles constituting the toner for developing an electrostatic image contain at least a fatty acid metal salt on the surface as an external additive, and the ridgeline of a cleaning blade having an edge angle in the range of 90 to 130° is pressed against the surface of the photoreceptor, and the effective contact angle of the cleaning blade is in the range of 7 to 20°. This feature is a technical feature common to or corresponding to each of the following embodiments (configurations).

[0021] In one embodiment of the present invention, the edge angle is preferably an obtuse angle of 95° or more, from the viewpoint of sufficiently improving the lubricity of the surface.

[0022] Furthermore, it is preferable that the thermoplastic resin having a LUMO level lower than 1.4 eV is a polyimide resin containing an electron-withdrawing group, from the viewpoint of enhancing electron-accepting properties and improving affinity with fatty acid metal salts.

[0023] The edge angle is preferably 110° or less from the viewpoint of sufficiently improving the lubricity of the surface.

[0024] From the viewpoint of sufficiently improving the lubricity of the surface, it is preferable that the amount of the fatty acid metal salt added is within a range of 0.20 to 0.30% by mass relative to the toner base particles.

[0025] The fatty acid metal salt is preferably zinc stearate from the viewpoint of improving the lubricity of the surface.

[0026] The present invention, its components, and embodiments for carrying out the present invention will be described in detail below. In this application, the symbol "to" is used to mean that the numerical values ​​before and after it are included as lower and upper limits.

[0027] [Outline of the Electrophotographic Image Forming System of the Present Invention] The electrophotographic image forming system of the present invention comprises at least the steps of forming an electrostatic latent image on a photoreceptor, developing the image using a toner for developing an electrostatic image, and removing the toner for developing an electrostatic image by pressing a ridgeline of a cleaning blade against the surface of the photoreceptor, wherein the photoreceptor has a photosensitive layer and a surface layer on a conductive support, the surface layer contains a thermoplastic resin having a LUMO level lower than 1.4 eV, the toner particles constituting the toner for developing an electrostatic image contain at least a fatty acid metal salt on the surface as an external additive, and the ridgeline of a cleaning blade having an edge angle in the range of 90 to 130° is pressed against the surface of the photoreceptor, and the effective contact angle of the cleaning blade is in the range of 7 to 20°.

[0028] 1. Electrophotographic photoreceptor The photoreceptor according to the present invention is an electrophotographic photoreceptor for use in an electrophotographic photosensitive type image forming apparatus, and the photoreceptor has a photosensitive layer and a surface layer on a conductive support, and the surface layer contains at least a thermoplastic resin having a LUMO level lower than 1.4 eV.

[0029] The thermoplastic resin having a LUMO level lower than 1.4 eV is preferably a polyimide resin containing an electron-withdrawing group, from the viewpoint of enhancing electron-accepting properties and improving affinity with fatty acid metal salts.

[0030] The thermoplastic resin preferably contains a charge transport material.

[0031] The electrophotographic photoreceptor has a conductive support, a photosensitive layer, and a surface layer. However, the present invention may include other configurations as long as the object and effect of the present invention are not impaired. For example, other layers such as an intermediate layer may be provided between the conductive support and the photosensitive layer, if necessary.

[0032] Conventional low-molecular-weight electron-accepting compounds tend to be unevenly distributed within the surface layer, and the unevenly distributed electron-accepting compound may trap charges moving within the surface layer. In contrast, in the electrophotographic photoreceptor according to the present invention, the structure having electron-accepting properties is supported by a thermoplastic resin, and therefore the structure is unlikely to be unevenly distributed within the surface layer, and the above-mentioned charge trapping is unlikely to occur.

[0033] (1.1) Conductive support The support used in the present invention may be any structure that is electrically conductive and capable of supporting the photosensitive layer, such as a cylindrical or columnar structure. The size of the conductive support is appropriately selected depending on the application of the electrophotographic photoreceptor. The material of the conductive support is not particularly limited.

[0034] Examples of conductive supports include metals such as aluminum, copper, chromium, nickel, zinc, and stainless steel molded into a drum or sheet shape; metal foils such as aluminum and copper laminated onto drum-shaped or sheet-shaped plastic films; drum-shaped or sheet-shaped plastic films onto which aluminum, indium oxide, tin oxide, or the like has been vapor-deposited; and drum-shaped or sheet-shaped metals, plastics, or paper onto which a conductive layer has been formed by applying a conductive material alone or a composition containing a conductive material and a binder resin.

[0035] (1.2) Photosensitive layer The photosensitive layer may contain a charge generating material capable of generating charges and a charge transport material having charge transport properties, and may be composed of, for example, a charge generating layer containing a charge generating material and a charge transport layer containing a charge transport material. On the other hand, the charge generating material and the charge transporting material may be contained in one layer (charge generating / transporting layer). However, if the charge generating layer and the charge transporting layer are constructed separately, the residual potential is less likely to increase when the electrophotographic photosensitive member is used repeatedly, and further, the properties of each layer can be easily controlled depending on the purpose of the electrophotographic photosensitive member. Hereinafter, an example in which the charge generating layer and the charge transporting layer are formed separately will be described, but the photosensitive layer of the electrophotographic photoreceptor according to the present invention is not limited to this embodiment.

[0036] (charge generation layer) The charge generating layer may be any layer that can generate charges when irradiated with light, and may be, for example, a layer containing a charge generating substance and a binder resin.

[0037] The charge generating material is not particularly limited, and known charge generating materials can be used. Examples include azo pigments such as Sudan Red and Diane Blue; quinone pigments such as pyrenequinone and anthanthrone; quinocyanine pigments; perylene pigments; indigo pigments such as indigo and thioindigo; phthalocyanine pigments such as titanyl phthalocyanine; and the like. The charge generating layer may contain only one of these charge generating materials, or may contain two or more of them.

[0038] On the other hand, known resins can also be used as the binder resin. Examples thereof include 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, polyvinyl carbazole resin, and copolymers thereof (e.g., vinyl chloride-vinyl acetate copolymer resin, vinyl chloride-vinyl acetate-maleic anhydride copolymer resin, etc.). The charge generating layer may contain only one of these binder resins, or may contain two or more of them.

[0039] The amount of the charge generating material in the charge generating layer is preferably within a range of 1 to 600 parts by mass, more preferably within a range of 50 to 500 parts by mass, per 100 parts by mass of the binder resin. When the amount of the charge generating material is within this range, a sufficient amount of charge can be generated.

[0040] The thickness of the charge generating layer is appropriately selected depending on the characteristics of the charge generating material, the characteristics and mixing ratio of the binder resin, etc., but is preferably in the range of 0.01 to 5 μm, more preferably in the range of 0.05 to 3 μm. When the thickness of the charge generating layer is within this range, the charge generating ability tends to be stable, and the layer can have a sufficiently high strength.

[0041] (charge transport layer) The charge transport layer may be any layer that can transport the charges generated in the charge generation layer, and may be, for example, a layer containing a charge transport substance and a binder resin.

[0042] The charge transport material may be any material capable of transporting charges, and known compounds may be used. Examples of the charge transport material include carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline compounds, oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, benzidine derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene, and poly-9-vinylanthracene. The charge transport layer may contain only one of these compounds, or may contain two or more of them.

[0043] On the other hand, known resins can also be used as the binder resin. Examples include polycarbonate resin, polyacrylate resin, polyester resin, polystyrene resin, styrene-acrylonitrile copolymer resin, polymethacrylate resin, styrene-methacrylate copolymer resin, etc. Among these, polycarbonate resin is preferred, and polycarbonate resin containing a structure such as bisphenol A (BPA), bisphenol Z (BPZ), dimethyl BPA, or BPA-dimethyl BPA copolymer is particularly preferred from the viewpoints of crack resistance, abrasion resistance, and anti-static properties. The charge transport layer may contain only one of these compounds, or may contain two or more of them.

[0044] The charge transport layer may contain various additives such as antioxidants and silicone oils, as long as the objects and effects of the present invention are not impaired. Specific examples of antioxidants include compounds described in JP-A No. 2000-305291.

[0045] The amount of the charge transport material in the charge transport layer is preferably within a range of 10 to 500 parts by weight, more preferably within a range of 20 to 100 parts by weight, per 100 parts by weight of the binder resin. When the amount of the charge transport material is within this range, the charge transporting properties of the charge transport layer are improved.

[0046] The thickness of the charge transport layer is suitably selected depending on the characteristics of the charge transport material and binder resin, and the mixing ratio thereof, but is preferably in the range of 5 to 40 μm, more preferably in the range of 10 to 30 μm. When the thickness of the charge transport layer is within this range, the charge transport ability is likely to be stable, and the layer can have a sufficiently high strength.

[0047] (1.3) Surface layer The surface layer functions as a layer for protecting the above-mentioned photosensitive layer from external electrical and mechanical forces. The surface layer may be any layer containing a thermoplastic resin having a LUMO level lower than 1.4 eV, and it is preferable that the thermoplastic resin is a polyimide resin containing an electron-withdrawing group, from the viewpoint of enhancing electron-accepting properties and improving affinity with fatty acid metal salts. In addition, other components may be included as necessary.

[0048] The thermoplastic resin functions as a material for binding the charge transport material in the surface layer, that is, as a binder resin.

[0049] (1.3.1) Electron-accepting In the present invention, the electron-accepting property of a thermoplastic resin is determined by indirectly estimating the LUMO level of the thermoplastic resin from a charge-transfer absorption band in the optical absorption spectrum observed in a mixed system in which the thermoplastic resin is combined with an electron donor (reference substance) whose highest occupied molecular orbital (HOMO) level is known, as will be described later.

[0050] (Method for confirming the presence or absence of electron-accepting properties) In the present invention, a fatty acid metal salt (lubricant) is used in combination with a resin having electron-accepting properties, which increases the affinity and makes it easier for the lubricant to be fixed to the photoreceptor. Therefore, a method for confirming whether a resin has electron accepting properties will be described below.

[0051] It is difficult to directly identify the lowest unoccupied molecular orbital (LUMO) level of a thermoplastic resin itself, but it can be indirectly estimated from the charge-transfer absorption band when combined with an electron donor (reference substance) whose highest occupied molecular orbital (HOMO) level is known. The HOMO level of the reference substance can be measured relatively easily using a commercially available photoelectron spectrometer (for example, AC-3 manufactured by Riken Keiki Co., Ltd.). FIG. 4 is a conceptual diagram showing the observation of an optical absorption spectrum in a mixed system of an electron donor (reference substance) and a thermoplastic resin.

[0052] In the present invention, tetramethyl-p-phenylenediamine (reference substance A, HOMO level 5.0 eV) and 4-propylbiphenyl-bis(4-methylphenyl)amine (reference substance B, HOMO level 5.6 eV, CTM-3), which are represented by the chemical formulas below, are used as electron donors (reference substances). When determining whether a thermoplastic resin has electron-accepting properties, a thermoplastic resin that can be determined to have electron-accepting properties in a mixed system of the thermoplastic resin and reference substance A and that can be determined to have electron-accepting properties in a mixed system of the thermoplastic resin and reference substance B is preferred, as it has higher electron-accepting properties.

[0053] [ka]

[0054] [ka]

[0055] In the following description, an example will be described in which the presence or absence of electron-accepting property is confirmed using a compound reference substance A having a structure represented by the following chemical formula as an electron donor (reference substance).

[0056] First, the target thermoplastic resin is extracted from the surface layer. The extraction method involves dissolving the surface layer (thermoplastic resin) in an appropriate solvent, separating the components in the surface layer by a known method, and then separating out the desired thermoplastic resin. Then, the thermoplastic resin and an electron donor (reference substance A) are mixed in a mass ratio of 2:1, and the mixture is dissolved in an appropriate solvent. Then, the optical absorption spectrum is measured using a commercially available spectrophotometer (for example, U-3900 manufactured by Hitachi High-Tech Science Corporation).

[0057] On the other hand, the optical absorption spectrum is also measured when only the electron donor (reference substance A) is dissolved in a solvent. The optical absorption spectrum resulting from the transition from the HOMO level to the LUMO level of reference material A was observed in the wavelength region below 340 nm (equivalent to 3.6 eV). Since the HOMO level of reference material A is 5.0 eV, it can be seen that the LUMO level of reference material A is 1.4 eV. The optical absorption spectrum is then compared with that of the system containing the thermoplastic resin. If a new absorption band appears in the wavelength region of 340 nm (equivalent to 3.6 eV) or more in the system containing the thermoplastic resin, it is determined that a charge transfer absorption band resulting from a transition to the LUMO level of the thermoplastic resin, which is located lower than 1.4 eV, has appeared. In other words, the thermoplastic resin has electron accepting properties.

[0058] Even if the charge-transfer absorption band exists, there are cases where it cannot be observed sufficiently because it is buried in the intramolecular transition absorption of the electron donor (reference substance A) itself. In such a thermoplastic resin, the LUMO level is higher than 1.4 eV, and therefore it is determined in the present invention that it does not have electron-accepting properties.

[0059] Furthermore, when a new absorption band appears in the wavelength range of 370 nm or more in combination with reference material B (CTM-3 HOMO level 5.6 eV), it can be said that the LUMO level of the thermoplastic resin is lower than 2.3 eV. Therefore, in the present invention, a thermoplastic resin that, when combined with reference substance B, produces a new absorption band is more preferable.

[0060] As described above, examples of thermoplastic resins having electron accepting properties include polyimide resins, polyimide amide resins, polyetherimide resins, polyether ether ketone resins, polysulfone resins, polyether sulfone resins, polyether sulfide resins, polycarbonate resins, and the like. Among these, polyimide resins are preferred. Furthermore, it is preferable that these thermoplastic resins have an electron-withdrawing group such as a halogen atom (fluorine, chlorine, bromine, iodine), a cyano group, a nitro group, an acetyl group, a formyl group, etc., since this further enhances the electron-accepting property of the thermoplastic resin. The surface layer may contain only one type of the above thermoplastic resin, or two or more types.

[0061] (1.3.2) Polyimide resin The thermoplastic resin is preferably a polyimide resin that is soluble in a solvent (hereinafter also referred to as a "solvent-soluble polyimide resin"). "Soluble in a solvent" means that when 10 g of the polyimide resin in question is dissolved in 100 g of an appropriate organic solvent at 25°C, the total light transmittance of the solution in the visible light region is 80% or more, and particles of 100 nm or larger are not formed in the organic solvent.

[0062] The solvent-soluble polyimide resin that can be used as the thermoplastic resin may be a commercially available product, and specific examples thereof include Sixef-44 (manufactured by Hoechst Celanese), KPI-MX300F (manufactured by Kawamura Sangyo Co., Ltd.), PI-100 (manufactured by Maruzen Petrochemical Co., Ltd.), and Q-AD-X1390 (manufactured by PI Technical Research Institute Co., Ltd.).

[0063] (1.3.3) Other binder resins The surface layer may further contain a binder resin component that functions as a binder resin in addition to the above-mentioned thermoplastic resin. However, the amount of the binder resin component is preferably 25 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of the thermoplastic resin content. The type of binder resin component is not particularly limited, and includes known thermoplastic resins that are compatible with the above-mentioned thermoplastic resins. Examples include polycarbonate, polyarylate, and the like.

[0064] (1.3.4) Charge transport material On the other hand, the charge transport material may be any material having charge transport properties, and known compounds can be used. Examples of the charge transport material include carbazole derivatives, oxazole derivatives, oxadiazole derivatives, thiazole derivatives, thiadiazole derivatives, triazole derivatives, imidazole derivatives, imidazolone derivatives, imidazolidine derivatives, bisimidazolidine derivatives, styryl compounds, hydrazone compounds, pyrazoline compounds, oxazolone derivatives, benzimidazole derivatives, quinazoline derivatives, benzofuran derivatives, acridine derivatives, phenazine derivatives, aminostilbene derivatives, triarylamine derivatives, phenylenediamine derivatives, stilbene derivatives, benzidine derivatives, poly-N-vinylcarbazole, poly-1-vinylpyrene, and poly-9-vinylanthracene. The surface layer may contain only one type of charge transport material, or may contain two or more types of charge transport materials, and the charge transport materials are particularly preferably triarylamine derivatives and benzidine derivatives.

[0065] The amount of the charge transport material in the surface layer is preferably within a range of 10 to 500 parts by weight, more preferably within a range of 20 to 100 parts by weight, per 100 parts by weight of the thermoplastic resin. When the amount of the charge transporting material is within this range, the charge transporting property of the surface layer is improved, and image memory and the like are less likely to occur.

[0066] (1.3.5) Inorganic and / or organic particles The surface layer may contain inorganic particles and / or organic particles in addition to the thermoplastic resin and charge transport material.

[0067] Examples of inorganic particles include silica particles, tin oxide particles, aluminum oxide particles, titanium oxide particles, calcium titanate particles, and the like. Examples of organic particles include styrene-acrylic particles, melamine particles, polyfluoroethylene particles, silicone particles, and the like. Among these, silica particles, tin oxide particles, and styrene-acrylic particles are preferred. Furthermore, the average primary particle size of the inorganic particles and organic particles is preferably within a range of 10 to 1000 nm from the viewpoint of adjusting the surface roughness of the surface layer. The average primary particle size is defined as the average value of 100 primary particle sizes measured directly from an electron microscope image.

[0068] The total amount of the inorganic particles and the organic particles is preferably in the range of 1 to 50% by mass, more preferably in the range of 2 to 20% by mass, based on the total amount of the surface layer. When the total amount of the inorganic particles and the organic particles is within this range, the electron accepting property and the charge transporting property of the surface layer are unlikely to be impaired.

[0069] (1.3.6) Various additives Furthermore, the surface layer may contain various additives such as antioxidants and silicone oils, as long as the objects and effects of the present invention are not impaired. Examples of antioxidants include compounds described in JP-A-2000-305291.

[0070] (1.3.7) Thickness of the surface layer The thickness of the surface layer is appropriately selected depending on the properties of the thermoplastic resin and charge transport material, the mixing ratio thereof, etc., but is usually preferably in the range of 1 to 30 μm, more preferably in the range of 3 to 20 μm. When the thickness of the surface layer is within this range, the surface layer can sufficiently protect the photosensitive layer.

[0071] (1.3.8) Volume resistivity of the surface layer The volume resistivity of the surface layer is 1×10 12 Ωcm or more is preferable, 1×10 13 Ωcm or more is preferable, and 1×10 14 More preferably, it is Ωcm or more. The volume resistivity of the surface layer is 1×10 12 When the surface resistance is Ωcm or more, the surface of the electrophotographic photosensitive member has sufficient insulating properties, and good charging properties can be obtained. The volume resistivity is determined by measurement using a commercially available device (for example, Hiresta-UP (MCP-450) manufactured by Dia Instruments) at a temperature of 20°C, a relative humidity of 50%, and an applied voltage of 100V (for 1 minute).

[0072] (1.4) Other layers As described above, the photoreceptor may include other layers between the conductive support and the photosensitive layer, if necessary, and may include, for example, the following intermediate layers.

[0073] The intermediate layer is a layer for transferring electrons generated in the charge generating layer to the conductive support side. The intermediate layer may be, for example, a layer containing conductive fine particles and a binder resin.

[0074] Examples of conductive fine particles include various metal particles; metal oxide particles such as aluminum oxide, zinc oxide, titanium oxide, tin oxide, antimony oxide, indium oxide, and bismuth oxide; tin-doped indium oxide; antimony-doped tin oxide; and zirconium oxide. The intermediate layer may contain only one type of conductive fine particles, or may contain two or more types. When the intermediate layer contains two or more kinds of conductive fine particles, these may be in the form of a solid solution or may be fused together. The number average primary particle size of the conductive fine particles is preferably 0.3 μm or less, and more preferably 0.1 μm or less. The average primary particle size is defined as the average value of 100 primary particle sizes measured directly from an electron microscope image.

[0075] Examples of the binder resin include polyamide resin, casein, polyvinyl alcohol resin, nitrocellulose, ethylene-acrylic acid copolymer, vinyl chloride resin, vinyl acetate resin, polyurethane resin, and gelatin. The intermediate layer may contain only one type of binder resin, or may contain two or more types of binder resins. The intermediate layer preferably contains 20 to 400 parts by mass, and more preferably 50 to 200 parts by mass, of conductive fine particles per 100 parts by mass of binder resin. When the amount of the conductive fine particles is within this range, the layer can have sufficient conductivity.

[0076] The thickness of the intermediate layer is preferably in the range of 0.1 to 15 μm, more preferably in the range of 0.3 to 10 μm. When the thickness of the intermediate layer is within this range, the layer can have a sufficiently high strength.

[0077] (1.5) Layer structure of electrophotographic photoreceptor The layer structure of the electrophotographic photosensitive member is not particularly limited, and may be appropriately selected depending on the performance and application required of the electrophotographic photosensitive member. For example, the conductive support / charge generating layer / charge transport layer / surface layer may be laminated in this order, or the conductive support / charge generating / transport layer / surface layer may be laminated in this order. Alternatively, the conductive support / intermediate layer / charge generation layer / charge transport layer / surface layer may be laminated in this order, or the conductive support / intermediate layer / charge generation / transport layer / surface layer may be laminated in this order.

[0078] (1.6) Manufacturing method of electrophotographic photoreceptor The electrophotographic photoreceptor described above can be manufactured by preparing a conductive support, and carrying out a step of forming a photosensitive layer on the conductive support (photosensitive layer forming step), and a step of forming a surface layer on the photosensitive layer (surface layer forming step). Before forming the photosensitive layer, a step of forming an intermediate layer on the conductive support (intermediate layer forming step) may be carried out. The intermediate layer forming step, the photosensitive layer forming step, and the surface layer forming step will be described below, but the method for producing the electrophotographic photoreceptor of the present invention is not limited to these methods.

[0079] (1.6.1) Intermediate layer formation process In the intermediate layer forming step, the above-mentioned conductive support is prepared, and the above-mentioned intermediate layer is formed on the conductive support. The intermediate layer can be formed by applying an intermediate layer composition containing the conductive fine particles, the binder resin, and a solvent, and then solidifying the composition.

[0080] Examples of the solvent contained in the intermediate layer composition are alcohols having 1 to 4 carbon atoms, such as methanol, ethanol, n-propyl alcohol, isopropyl alcohol, n-butanol, t-butanol, and sec-butanol, which are preferred from the viewpoint of the coatability of the intermediate layer composition. Furthermore, from the viewpoint of improving the storage stability of the intermediate layer composition and the dispersibility of the conductive fine particles, the intermediate layer composition may further contain benzyl alcohol, toluene, cyclohexanone, tetrahydrofuran, or the like.

[0081] The method for preparing the intermediate layer composition is not particularly limited. For example, the solvent and binder resin may be mixed first, and then the conductive fine particles may be added. The conductive fine particles can be dispersed using an ultrasonic disperser, a ball mill, a sand grinder, a homomixer, or the like.

[0082] The method for applying the intermediate layer composition is not particularly limited, and may be a dip coating method, a spray coating method, a spinner coating method, a bead coating method, a blade coating method, a beam coating method, a circular amount-controlled coating method, or the like. Furthermore, the method for drying the intermediate layer composition can be appropriately selected from known drying methods depending on the type of solvent and the thickness of the film to be formed, and heat drying is particularly preferred.

[0083] (1.6.2) Photosensitive layer formation process In the photosensitive layer forming step, a photosensitive layer is formed on the conductive support or on the intermediate layer. The method for forming the photosensitive layer is appropriately selected depending on the layer structure of the photosensitive layer. For example, when the photosensitive layer consists of only one layer of a charge generation / transport layer, a charge generation / transport layer composition containing a charge generation substance, a charge transport substance, a binder resin, a solvent, etc. is prepared, and this is applied to the intermediate layer and solidified to form the photosensitive layer. On the other hand, when the photosensitive layer is composed of two layers, a charge generating layer and a charge transporting layer, the layers are formed in order by the following method.

[0084] (Formation of Charge Generation Layer) The method for forming the charge generation layer is not particularly limited, and the charge generation layer can be formed by applying a charge generation layer composition containing the above-mentioned charge generation material, the above-mentioned binder resin, and a solvent onto the above-mentioned conductive support (or onto the intermediate layer if an intermediate layer formation step is performed) and solidifying it.

[0085] Examples of solvents used in the charge generating layer composition include toluene, xylene, methyl ethyl ketone, cyclohexane, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, methyl cellosolve, ethyl cellosolve, tetrahydrofuran, 1-dioxane, 1,3-dioxolane, pyridine, diethylamine, etc. The charge generating layer composition may contain only one of these or two or more of them.

[0086] The method for preparing the charge generating layer composition may be any method that allows the charge generating material, binder resin, and solvent to be thoroughly mixed. For example, the binder resin and the solvent may be mixed together, and then the charge generating material may be added. When preparing the charge generating layer composition, a dispersing device such as an ultrasonic disperser, a ball mill, a sand grinder, or a homomixer can be used.

[0087] The method for applying the charge generating layer composition is not particularly limited, and any known method can be used. Examples include dip coating, spray coating, spinner coating, bead coating, blade coating, beam coating, circular volumetric coating, and the like. The method for solidifying the charge generating layer composition is not particularly limited, and the composition may be solidified by removing the solvent by heating or the like, or may be solidified by air drying or the like.

[0088] (Formation of charge transport layer) The method for forming the charge transport layer is not particularly limited, and the charge transport layer can be formed by applying a charge transport layer composition containing the charge transport material, the binder resin, and a solvent, and then solidifying the composition.

[0089] Examples of the solvent include toluene, xylene, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, etc. The charge transport layer composition may contain only one of these solvents or two or more of them.

[0090] The method for mixing the charge transport material, binder resin, and solvent is not particularly limited. The mixing can be carried out using a known stirring device or the like. Furthermore, the method for applying the charge transport layer composition is not particularly limited, and any known method can be used. Examples of such methods include dip coating, spray coating, spinner coating, bead coating, blade coating, beam coating, circular amount-controlled coating, etc. The method for solidifying the charge transport layer composition is not particularly limited, and may involve, for example, removing the solvent by heating or the like, or may involve natural drying or the like.

[0091] (1.6.3) Surface layer formation process In the surface layer forming step, a surface layer is formed on the above-mentioned photosensitive layer. The method for forming the surface layer is not particularly limited, and the surface layer can be formed, for example, by applying a surface layer composition containing the above-mentioned thermoplastic resin and solvent, and, if necessary, other components such as the above-mentioned charge transport material, onto the photosensitive layer using a known method, and then solidifying the composition.

[0092] Examples of the solvent contained in the surface layer composition, i.e., the solvent capable of dissolving or dispersing the thermoplastic resin and the charge transport material, include toluene, xylene, methyl ethyl ketone, cyclohexanone, ethyl acetate, butyl acetate, methanol, ethanol, propanol, butanol, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, dichloromethane, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, etc. The surface layer composition may contain only one of these, or may contain two or more of them.

[0093] Among the above, solvents having a boiling point in the range of 40 to 150°C are preferred, and solvents having a boiling point in the range of 60 to 120°C are more preferred. When the boiling point of the solvent is 150° C. or lower, the amount of solvent remaining in the surface layer after drying tends to be small. On the other hand, if the boiling point of the solvent is 40° C. or higher, the solvent is less likely to volatilize during storage or application of the surface layer composition, and the surface layer composition becomes easier to handle. When two or more solvents are contained, it is preferable that the boiling points of the respective component solvents are within the above range.

[0094] The method for mixing the thermoplastic resin, charge transport material, solvent, etc. is not particularly limited. The mixing can be carried out using a known stirring device or the like. The method for applying the surface layer composition is not particularly limited, and any known method can be used. Examples include dip coating, spray coating, spinner coating, bead coating, blade coating, beam coating, circular volumetric coating, and the like. Furthermore, the method for solidifying the surface layer composition is not particularly limited, and for example, the surface layer composition may be solidified by removing the solvent by heating or the like, or may be solidified by natural drying or the like. The temperature when removing the solvent is preferably in the range of 50 to 140°C, more preferably in the range of 80 to 130°C. As described above, when a solvent-soluble polyimide resin is used as the thermoplastic resin, a surface layer containing a polyimide resin can be formed without heating the surface layer composition to a high temperature. Furthermore, there is an advantage that unreacted functional groups are less likely to remain in the surface layer.

[0095] 2. Cleaning blade (2.1) Definitions of terms related to cleaning blades (Contact force) The contact force is the contact force of the cleaning blade C L When the cleaning blade C is brought into contact with the surface of the photoreceptor 10, L This is the force applied to the surface of the photoreceptor 10 as a result of applying a load to the surface.

[0096] (effective contact angle) The effective contact angle is the angle between the rubber material and the ridgeline on the downstream side of the image carrier in the direction of rotation when the rubber material is bent by pressing the rubber material against the image carrier. As shown in Figure 5, L The actual angle θ1 formed by the tip of the photosensitive member 10 and the surface of the photosensitive member 10 is Cleaning blade C according to the present invention L is characterized in that 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 calculated using the cross-sectional shape and physical properties such as Young's modulus of the material.

[0097] (Rigid body contact angle) The rigid body contact angle is L is a design value used when the surface of the photosensitive member is brought into contact with the surface of the photosensitive member. The angle θ2 shown in FIG. 5 is the angle L is assumed to be a rigid body (shown by the dotted line), L and the tip of the photoconductor C L is the rigid contact angle between the surface of

[0098] (edge ​​angle) The edge angle is the angle θ shown in Figure 5. e As shown, this is the angle of the tip ridge of the rubber material, which is the contact point C with the photosensitive member surface.

[0099] (free length) The free length is the length of the rubber material when it is pressed against the metal plate. g The length of the part protruding from the sheet metal P g This is the portion L in Figure 5 excluding the adhesive portion.

[0100] (wedge angle) The wedge angle is the angle formed between the rubber material and the ridge line on the upstream side in the rotation direction of the photoreceptor 10, as shown by angle θ3 in FIG.

[0101] (2.2) Cleaning Blade Overview The electrophotographic image forming system of the present invention includes a step of removing the toner for developing the electrostatic image by pressing the edge of a cleaning blade against the surface of the photosensitive member. The cleaning blade has an edge angle of 90 to 130° and is pressed against the surface of the photoreceptor at its tip ridge, and the effective contact angle of the cleaning blade is within the range of 7 to 20°.

[0102] FIG. 5 is a conceptual side view of the relationship between the cleaning blade according to the present invention and the electrophotographic photosensitive member. As shown in Figure 5, the cleaning blade has an edge angle of θ e The tip edge is arranged to abut against the surface of the photosensitive member 10 so that the effective abutment angle θ1 falls within the above range (the portion where the tip edge abuts against the surface of the photosensitive member 10 is referred to as abutment portion C). Cleaning Blade C L The wedge angle θ3, which is the angle between the tip surface and the tangent line, is an acute angle.

[0103] The edge angle θ e When the wedge angle θ3 is 90° or more, the wedge angle θ3 becomes small, and a shearing action that cleaves and spreads the layered crystals of the fatty acid metal salt is obtained near the blade nip, thereby improving surface lubricity.

[0104] The edge angle θ e If the wedge angle θ3 is greater than 130°, the wedge angle θ3 becomes too small, and the toner particles and external additive particles present near the blade nip are pressed perpendicularly to the photosensitive drum surface, resulting in excessive abrasion and insufficient lubrication. Furthermore, the force with which the trapped particles push the blade vertically upward increases, which may result in poor cleaning.

[0105] In one embodiment of the present invention, the edge angle θ e However, from the viewpoint of sufficiently improving the lubricity of the surface, an obtuse angle of 95° or more is preferable, and an obtuse angle of 110° or less is even more preferable.

[0106] When the effective contact angle θ1 is less than 7°, the effective contact angle θ1 is too low, so the wedge angle θ3 becomes large, and the shearing action for cleaving and spreading the layered crystals of the fatty acid metal salt cannot be obtained sufficiently. Furthermore, the peak surface pressure at the nip portion becomes smaller, which may result in poor cleaning.

[0107] The cleaning blade C according to the present invention L The effective contact angle θ1 is 7° or more, and is more preferably 9° or more from the viewpoint of the effect.

[0108] If the effective contact angle θ1 is greater than 20°, the effective contact angle θ1 is too large, and the wedge angle θ3 becomes too small, so that the toner particles are not easily attracted to the cleaning blade C. L If this occurs, the force pushing the nozzles up in the vertical direction will be too large, which may result in poor cleaning. There is also a risk of blade curling.

[0109] The effective contact angle θ1 of the cleaning blade according to the present invention is 20° or less, and is more preferably 17° or less from the viewpoint of achieving the desired effect.

[0110] (2.3) Cleaning Blade Configuration Cleaning blade C according to the present invention L It is mainly made of rubber material. The rubber material portions do not all need to be made of the same material, and may be, for example, a two-layer blade consisting of a contact layer that forms the edge portion and a support layer. In the case of a two-layer structure, for example, the material of the support layer may have a lower permanent deformation rate than the material of the contact layer in order to prevent settling.

[0111] (Material) Cleaning blade C according to the present invention L The material is preferably urethane rubber from the viewpoint of abrasion resistance and moldability.

[0112] (hardness) Cleaning blade C according to the present invention L The rubber hardness is preferably within the range of 65 to 85° in terms of hardness values ​​defined by JIS-A. If the rubber hardness is 65° or more, the blade is less likely to be pulled in, and the wedge angle θ3 does not become too small. Furthermore, if the rubber hardness is 85° or less, the surface pressure will not be too high and the abrasive force will not be too strong, and the fatty acid metal salt will not be easily removed, so that a sufficient lubricating effect can be obtained.

[0113] (rebound resilience) Cleaning blade C according to the present invention L The impact resilience is preferably within the range of 10 to 40°. If the impact resilience is within the above range, vibrations are appropriately suppressed, the wedge angle θ3 is stabilized, and the shearing action of the fatty acid metal salt can be more effectively exerted.

[0114] (shape) Cleaning blade C according to the present invention L It is preferable that the free length L is in the range of 8.5 to 11.5 mm and the thickness is in the range of 1.7 to 2.5 mm.

[0115] (Conditions of contact) Cleaning blade C according to the present invention L The contact force is preferably within the range of 12 to 30 (N / m) from the viewpoint of preventing incomplete wiping and peeling. If the contact force is 12 (N / m) or more, there is no risk of leaving any areas unwiped, and if it is 30 (N / m) or less, there is no risk of peeling.

[0116] 3. Fatty acid metal salts The toner particles constituting the electrostatic image developing toner according to the present invention contain at least a fatty acid metal salt on the surface as an external additive.

[0117] From the viewpoint of sufficiently improving the lubricity of the surface, it is preferable that the amount of the fatty acid metal salt added is within a range of 0.20 to 0.30% by mass relative to the toner base particles. If the amount of the fatty acid metal salt added is within the range of 0.20 to 0.30% by mass relative to the toner base particles, the spreading effect is sufficient, but the coverage rate of the fatty acid metal salt does not decrease, and the surface lubricity can be sufficiently improved.

[0118] The fatty acid metal salt is preferably zinc stearate from the viewpoint of improving the lubricity of the surface. Zinc stearate has a moderate negative chargeability and a moderate affinity with the electron-accepting resin. Furthermore, the spacing between the layered crystals, determined by the alkyl chain length, is appropriate, and the cleavage and spreadability are good, further improving the lubricity of the surface.

[0119] If the particle size of the fatty acid metal salt is small, it can be applied more uniformly and the lubricity of the surface can be improved. From the above viewpoint, the particle size is preferably 4 μm or less, and more preferably 2 μm or less. The fatty acid metal salt has a small particle size as described above, so that it can be applied uniformly and the lubricity of the surface can be improved. In addition, fatty acid metal salts having a large particle size of 10 μm or more may be used in combination with fatty acid metal salts having a small particle size. Since fatty acid metal salts with large particle diameters are more likely to separate from the toner base particles, the total amount of fatty acid metal salts supplied to the photoreceptor can be increased.

[0120] (Affinity between thermoplastic resin and fatty acid metal salt) The thermoplastic resin having electron-accepting properties contained in the surface layer of the electrophotographic photosensitive member according to the present invention has a high affinity with the fatty acid metal salt used as a lubricant externally added to the toner for developing electrostatic images, which will be described later. This makes it easier for the fatty acid metal salt to be fixed to the surface of the electrophotographic photosensitive member, thereby making it possible to suppress toner filming.

[0121] 4. 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 contains toner particles comprising toner base particles and external additives attached to the surfaces of the toner base particles. In particular, as an external additive, at least a fatty acid metal salt acting as a lubricant is contained on the surface of the toner particles. In this specification, the term "toner base particles" refers to particles that form the base of "toner particles." The "toner base particles" contain at least a binder resin, and may also contain other components such as a colorant, a release agent (wax), and a charge control agent, as necessary. Particles formed by adding and adhering external additives to the surfaces of "toner base particles" are generally called "toner particles." However, when the toner base particles themselves are used as they are without adding and adhering an external additive, the toner base particles themselves may also be referred to as "toner particles." The term "toner" refers to an aggregate of "toner particles."

[0122] (4.1) Toner base particles As the toner base particles according to the present invention, known toner base particles can be used. Specifically, such toner base particles are composed of toner base particles containing at least a binder resin and, if necessary, a colorant. The toner base particles may further contain other components such as a release agent and a charge control agent, if necessary.

[0123] (4.2) Binder resin As the binder resin, known resins can be used, and for example, amorphous resins and crystalline resins can be suitably used. In particular, it is preferable that the resin contains a styrene-acrylic resin and a crystalline polyester resin, which will be described later.

[0124] (4.2.1) Amorphous resin The amorphous resin that can be used in the present invention is not particularly limited, but known amorphous resins such as vinyl resins and polyester resins as described below, as well as urethane resins and urea resins can be preferably used.

[0125] (vinyl resin) When a vinyl resin is used as the amorphous resin, the vinyl resin is not particularly limited as long as it is a polymer of a vinyl compound, and examples thereof include acrylate resin, styrene-acrylate resin, and ethylene-vinyl acetate resin. These may be used alone or in combination of two or more. Among the above vinyl resins, styrene-acrylic acid ester resin (styrene-acrylic resin) is preferred in consideration of plasticity during thermal fixing. Therefore, although detailed description will be omitted, it is preferable to use, as the styrene monomer, styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, and p-ethylstyrene; as the (meth)acrylic acid ester monomer, acrylic acid ester monomers such as methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, and isobutyl acrylate; 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 alone or in combination of two or more.

[0126] Other monomers may also be polymerized, and examples thereof include 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, and polyethylene glycol mono(meth)acrylate. The method for producing the styrene-acrylic resin is not particularly limited, and it can be produced by emulsion polymerization or the like.

[0127] (polyester resin) When a polyester resin is used as the amorphous resin, the amorphous polyester resin refers to a resin that does not show a clear endothermic peak in differential scanning calorimetry (DSC) among known polyester resins obtained by a polycondensation reaction between a divalent or higher carboxylic acid (polycarboxylic acid) and a divalent or higher alcohol (polyalcohol). Specifically, a clear endothermic peak means a peak whose half-width is within 15°C when measured by differential scanning calorimetry (DSC) at a temperature rise rate of 10°C / min.

[0128] Examples of polycarboxylic acids include aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelic 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, and 1,18-octadecanedicarboxylic acid; aromatic dicarboxylic acids such as maleic acid, isophthalic acid, terephthalic acid, and naphthalenedicarboxylic acid; aliphatic unsaturated dicarboxylic acids such as maleic acid, fumaric acid, itaconic acid, citraconic acid, glutaconic acid, isododecenylsuccinic acid, n-dodecenylsuccinic acid, and n-octenylsuccinic acid; and divalent or higher carboxylic acids such as trimellitic acid, pyromellitic acid, naphthalenetricarboxylic acid, naphthalenetetracarboxylic acid, pyrenetricarboxylic acid, and pyrenetetracarboxylic acid.

[0129] Examples of polyhydric alcohols include 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-dodecanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, 1,20- Examples of the polyol include aliphatic diols such as eicosanediol; bisphenols such as bisphenol A and bisphenol F, and alkylene oxide adducts of bisphenols such as their ethylene oxide adducts and propylene oxide adducts; and trivalent or higher polyols such as glycerin, pentaerythritol, hexamethylolmelamine, hexaethylolmelamine, tetramethylolbenzoguanamine, and tetraethylolbenzoguanamine.

[0130] (4.2.2) Crystalline resin The toner base particles according to the present invention may contain a crystalline resin, and for example, the following crystalline polyesters and the crystalline resins described in paragraphs 0043 to 0102 of JP-A No. 2015-011325 can be suitably used. In particular, it is preferable from the viewpoint of production that the resin contains a hybrid crystalline polyester resin.

[0131] (Crystalline polyester resin) The crystalline polyester resin is 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 (polyalcohol), and refers to a resin unit that exhibits a clear endothermic peak rather than a stepwise endothermic change in differential scanning calorimetry (DSC) of the toner. Specifically, a clear endothermic peak means a peak whose half-width is 15°C or less when measured at a heating rate of 10°C / min by differential scanning calorimetry (DSC) as described in the Examples.

[0132] The crystalline polyester resin is not particularly limited as long as it is as defined above. For example, the crystalline polyester resin itself may be contained. Alternatively, the hybrid resin having a crystalline polyester resin unit may contain a resin having a structure in which other components are copolymerized in a main chain of a crystalline polyester resin unit, or a resin having a structure in which a crystalline polyester resin unit is copolymerized in a main chain made of other components, and a toner containing this resin may exhibit a clear endothermic peak as described above.

[0133] The crystalline polyester resin is produced from a polycarboxylic acid component and a polyhydric alcohol component. In this case, the crystalline polyester resin unit is composed of the number of carbon atoms C (acid) of the polycarboxylic acid component and the number of carbon atoms C (alcohol) of the polyhydric alcohol component, and the valences of the polycarboxylic acid component and the polyhydric alcohol component are preferably 2 to 3, and particularly preferably 2, respectively.

[0134] The method for forming the crystalline polyester resin is not particularly limited, and the resin can be formed by polycondensing (esterifying) the polycarboxylic acid and polyhydric alcohol using a known esterification catalyst.

[0135] The ratio of the polyhydric alcohol component to the polycarboxylic acid component is preferably such that the equivalent ratio [OH] / [COOH] of the hydroxy group [OH] of the diol component to the carboxy group [COOH] of the dicarboxylic acid component is 1.5 / 1 to 1 / 1.5, more preferably 1.2 / 1 to 1 / 1.2.

[0136] Examples of catalysts that can be used in producing the crystalline polyester resin 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; phosphorous compounds; phosphoric acid compounds; and amine compounds.

[0137] Specific examples of tin compounds include dibutyltin oxide, tin octoate, tin dioctoate, and salts thereof. Examples of titanium compounds include titanium alkoxides such as tetra-normal-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 triethanolaminate. The germanium compound may include germanium dioxide. Further, examples of the aluminum compound include oxides such as polyaluminum hydroxide, aluminum alkoxides, etc., and examples include tributylaluminate, etc. These may be used alone or in combination of two or more.

[0138] The polymerization temperature and polymerization time are not particularly limited, and the pressure in the reaction system may be reduced during the polymerization, if necessary.

[0139] Furthermore, in the case of a hybrid resin having a crystalline polyester resin unit, the content of the crystalline polyester resin unit is preferably within a range of 50 to 98% by mass with respect to the total amount of the hybrid resin. By setting the content within the above range, sufficient crystallinity can be imparted to the hybrid resin. The constituent components and content ratio of each unit in the hybrid resin can be identified by, for example, NMR measurement or methylation reaction P-GC / MS measurement.

[0140] Here, the hybrid resin contains, in addition to the crystalline polyester resin unit, an amorphous resin unit other than the polyester resin, which will be described in detail 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 an amorphous resin unit other than the polyester resin, but is preferably a graft copolymer. By forming a graft copolymer, it becomes easier to control the orientation of the crystalline polyester resin units, and sufficient crystallinity can be imparted to the hybrid resin.

[0141] Furthermore, from the above viewpoint, it is preferable that the crystalline polyester resin unit is grafted onto an amorphous resin unit other than the crystalline polyester resin as the main chain. That is, the hybrid crystalline polyester resin is preferably a graft copolymer having an amorphous resin unit other than polyester resin as the main chain and a crystalline polyester resin unit as the side chain.

[0142] By adopting the above-mentioned configuration, the orientation of the crystalline polyester resin units can be further enhanced, and the crystallinity of the hybrid resin can be improved.

[0143] The hybrid resin may further contain a substituent such as a sulfonic acid group, a carboxy group, or a urethane group. The substituent may be introduced into a crystalline polyester resin unit or into an amorphous resin unit other than the polyester resin, which will be described in detail below.

[0144] (Amorphous resin unit other than polyester resin) The non-polyester resin amorphous resin unit is a portion derived from an amorphous resin other than the above-mentioned crystalline polyester resin. The inclusion of amorphous resin units in hybrid resins (and even in toners) allows the chemical structure to be characterized by selecting an appropriate analytical method from among NMR measurement, P-GC / MS measurement, methylation reaction P-GC / MS measurement, etc., depending on the structure.

[0145] Furthermore, 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.

[0146] The amorphous resin unit is not particularly limited as long as it is as defined above. For example, with respect to a resin having a structure in which other components are copolymerized into a main chain of an amorphous resin unit, or a resin having a structure in which an amorphous resin unit is copolymerized into a main chain made of other components, if a toner containing this resin has the above-mentioned amorphous resin unit, then the resin corresponds to a hybrid resin having an amorphous resin unit.

[0147] The amorphous resin unit is preferably made of the same type of resin as the amorphous resin contained in the binder resin (that is, the 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 charging uniformity and the like are further improved.

[0148] Here, "same type of resin" means that characteristic chemical bonds are commonly contained in the repeating units. Furthermore, the "characteristic chemical bond" follows 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). That is, the chemical bonds that make up polymers classified into a total of 22 types, including 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."

[0149] Furthermore, when the resin is a copolymer, "same type of resin" refers to resins that have a characteristic chemical bond in common when the chemical structures of multiple monomer species that make up the copolymer contain monomer species having the above-mentioned chemical bond as constituent units. Therefore, even if the properties of the resins themselves are different from each other or the molar ratios of the monomer species that make up the copolymer are different from each other, they are considered to be the same type of resin as long as they have characteristic chemical bonds in common.

[0150] 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 have at least chemical bonds that constitute polyacrylic, and therefore are the same type of resin. 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, acrylic acid, terephthalic acid, and fumaric acid have at least a chemical bond that constitutes polyacrylic as a common chemical bond. Therefore, they are the same type of resin.

[0151] The resin component constituting the amorphous resin unit is not particularly limited, but examples thereof include a vinyl resin unit, a urethane resin unit, and a urea resin unit. Among these, vinyl resin units are preferred because their thermoplasticity is easily controlled. The vinyl resin unit is not particularly limited as long as it is a polymer of a vinyl compound, and examples thereof include an acrylate resin unit, a styrene-acrylate resin unit, and an ethylene-vinyl acetate resin unit. These may be used alone or in combination of two or more.

[0152] The method for forming the styrene-acrylic resin unit is not particularly limited, and examples thereof include a method in which a monomer is polymerized using a known oil-soluble or water-soluble polymerization initiator. Specific examples of oil-soluble polymerization initiators include the azo-based or diazo-based polymerization initiators and peroxide-based polymerization initiators shown below.

[0153] Examples of the azo or diazo polymerization initiator include 2,2'-azobis-(2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile, and azobisisobutyronitrile.

[0154] Examples of the peroxide polymerization initiator 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.

[0155] When resin particles are formed by emulsion polymerization, a water-soluble radical polymerization initiator can be used, such as persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, and hydrogen peroxide.

[0156] The content of the amorphous resin unit is preferably within a range of 3 to 50% by mass with respect to the total amount of the hybrid resin. Furthermore, the content is more preferably within the range of 5 to 30% by mass. By setting the content within the above range, sufficient crystallinity can be imparted to the hybrid resin.

[0157] (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 as long as it is a method capable of forming a polymer having a structure in which the crystalline polyester resin unit and the amorphous resin unit are molecularly bonded. Specific examples of methods for producing the hybrid resin include the following methods.

[0158] (1) A method for producing a hybrid resin by polymerizing an amorphous resin unit in advance and then carrying out a polymerization reaction to form a crystalline polyester resin unit in the presence of the amorphous resin unit. In this method, first, the monomers constituting the above-mentioned amorphous resin unit (preferably a vinyl monomer such as a styrene monomer and a (meth)acrylic acid ester monomer) are subjected to an addition reaction to form the amorphous resin unit. Next, a polycarboxylic acid and a polyhydric alcohol are polymerized in the presence of the amorphous resin unit to form a crystalline polyester resin unit. In this case, a hybrid resin is formed by condensation reaction of a polycarboxylic acid with a polyhydric alcohol and addition reaction of the polycarboxylic acid or polyhydric alcohol with the amorphous resin unit.

[0159] In the above method, it is preferable to incorporate a site in the crystalline polyester resin unit or the amorphous resin unit that allows these units to react with each other. Specifically, when forming the amorphous resin unit, in addition to the monomer that constitutes the amorphous resin unit, a compound having a site that can react with the carboxy group [—COOH] or hydroxy group [—OH] remaining in the crystalline polyester resin unit and a site that can react with the amorphous resin unit is also used. That is, this compound reacts with a carboxy group [—COOH] or a hydroxy group [—OH] in the crystalline polyester resin unit, thereby allowing the crystalline polyester resin unit to chemically bond with the amorphous resin unit. Alternatively, a compound may be used which is capable of reacting with a polyhydric alcohol or a polycarboxylic acid when forming the crystalline polyester resin unit and which has a site capable of reacting with the amorphous resin unit. By using the above method, a hybrid resin having a structure (graft structure) in which a crystalline polyester resin unit is molecularly bonded to an amorphous resin unit can be formed.

[0160] (2) A method in which a crystalline polyester resin unit and an amorphous resin unit are formed separately and then bonded to produce a hybrid resin. In this method, first, a polycarboxylic acid and a polyhydric alcohol are subjected to a condensation reaction to form a crystalline polyester resin unit. Separately from the reaction system for forming the crystalline polyester resin unit, the monomers constituting the above-mentioned amorphous resin unit are addition polymerized to form the amorphous resin unit. In this case, it is preferable to incorporate a site where the crystalline polyester resin unit and the amorphous resin unit can react with each other. The method for incorporating such a reactive site is as described above, and therefore a detailed description thereof will be omitted. Next, the crystalline polyester unit formed above is reacted with an amorphous resin unit to form a hybrid resin having a structure in which the crystalline polyester resin unit and the amorphous resin unit are molecularly bonded. Furthermore, when the reactive moiety is not incorporated into the crystalline polyester resin unit and the amorphous resin unit, a method may be employed in which a system in which the crystalline polyester resin unit and the amorphous resin unit coexist is formed, and a compound having a moiety capable of bonding to the crystalline polyester resin unit and the amorphous resin unit is added to the system. Then, a hybrid resin having a structure in which a crystalline polyester resin unit and an amorphous resin unit are molecularly bonded via the compound can be formed.

[0161] (3) A method of producing a hybrid resin by forming a crystalline polyester resin unit in advance and then carrying out a polymerization reaction to form an amorphous resin unit in the presence of the crystalline polyester resin unit. In this method, first, a polycarboxylic acid and a polyhydric alcohol are polymerized by condensation reaction to form a crystalline polyester resin unit. Next, the monomers constituting the amorphous resin units are polymerized in the presence of the crystalline polyester resin units to form the amorphous resin units. In this case, similarly to the above (1), it is preferable to incorporate a site in the crystalline polyester resin unit or the amorphous resin unit that allows these units to react with each other. The method for incorporating such a reactive site is as described above, and therefore a detailed description thereof will be omitted.

[0162] By using the above method, a hybrid resin having a structure (graft structure) in which an amorphous resin unit is molecularly bonded to a crystalline polyester resin unit can be formed. Among the above formation methods (1) to (3), method (1) is preferred because it is easy to form a hybrid resin having a structure in which crystalline polyester resin chains are grafted onto amorphous resin chains and because it simplifies the production process. In the method (1), the amorphous resin units are formed in advance and then the crystalline polyester resin units are bonded to them, so that the orientation of the crystalline polyester resin units tends to be uniform. Therefore, it is preferable because it is possible to reliably form a hybrid resin suitable for the toner defined in the present invention.

[0163] (4.3) Colorants As the colorant that can constitute the toner base particles, carbon black, magnetic materials, dyes, pigments, etc. can be used arbitrarily. As the carbon black, channel black, furnace black, acetylene black, thermal black, lamp black, etc. can be used. As magnetic materials, ferromagnetic metals such as iron, nickel, and cobalt, alloys containing these metals, ferromagnetic metal compounds such as ferrite and magnetite, alloys that do not contain ferromagnetic metals but become ferromagnetic when heat treated, such as alloys called Heusler alloys such as manganese-copper-aluminum and manganese-copper-tin, and chromium dioxide can be used.

[0164] Examples of magenta or red colorants 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.

[0165] Examples of colorants for orange or yellow include CI Pigment Orange 31, CI Pigment Orange 43, CI Pigment Yellow 12, CI Pigment Yellow 14, CI Pigment Yellow 15, CI Pigment Yellow 17, CI Pigment Yellow 74, CI Pigment Yellow 83, CI Pigment Yellow 93, CI Pigment Yellow 94, CI Pigment Yellow 138, CI Pigment Yellow 139, CI Pigment Yellow 155, CI Pigment Yellow 162, CI Pigment Yellow 180, CI Pigment Yellow 185, and CI Solvent Yellow 93.

[0166] 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.

[0167] These colorants can be used alone or in combination of two or more, as required. The amount of colorant added is preferably within a range of 1 to 30% by mass, more preferably within a range of 2 to 20% by mass, based on the total amount of toner base particles, and a mixture thereof can also be used. Within this range, color reproducibility of the image can be ensured. The dispersion diameter of the colorant in the toner is preferably in the range of 10 to 1000 nm, more preferably in the range of 50 to 500 nm, and even more preferably in the range of 80 to 300 nm, in terms of volume average particle diameter.

[0168] (4.4) Release agent The release agent constituting the toner base particles is not particularly limited, and known release agents can be used. Specific 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 sazol wax, dialkyl ketone waxes such as distearyl ketone, carnauba wax, montan wax, ester waxes such as behenic acid behenate, trimethylolpropane tribehenate, pentaerythritol tetrabehenate, pentaerythritol diacetate dibehenate, glycerin tribehenate, 1,18-octadecanediol distearate, trimellitate tristearyl, and distearyl maleate, and amide waxes such as ethylenediamine behenylamide and trimellitate tristearylamide.

[0169] The melting point of the release agent is preferably within a range of 40 to 160°C, and more preferably within a range of 50 to 120°C. By setting the melting point within the above range, the heat-resistant storage stability of the toner is ensured, and even when fixing is performed at a low temperature, stable toner image formation can be achieved without causing cold offset or the like. The content of the release agent in the toner base particles is preferably in the range of 1 to 30% by mass, and more preferably in the range of 5 to 20% by mass.

[0170] (4.5) Charge control agent Furthermore, a charge control agent can be added to the toner base particles according to the present invention, if necessary. As the charge control agent, various known agents can be used.

[0171] As the charge control agent, various known compounds that can be dispersed in an aqueous medium can be used, and specific examples thereof include nigrosine dyes, metal salts of naphthenic acid or higher fatty acids, alkoxylated amines, quaternary ammonium salt compounds, azo metal complexes, metal salicylate salts or metal complexes thereof, and the like.

[0172] The content of the charge control agent is preferably in the range of 0.1 to 10% by mass, more preferably in the range of 0.5 to 5% by mass, based on the total amount of the binder resin.

[0173] (4.6) External additives The toner particles constituting the electrostatic image developing toner according to the present invention contain at least a fatty acid metal salt as an external additive. From the viewpoint of improving the charging performance, fluidity or cleaning property of the toner, known inorganic fine particles, organic fine particles or lubricants may be added as external additives to the surface of the toner base particles. The toner particles constituting the toner for developing electrostatic images used in the electrophotographic image forming system of the present invention contain at least a fatty acid metal salt as a lubricant as an external additive. The fatty acid metal salt is as described above.

[0174] Preferred examples of inorganic fine particles include inorganic fine particles made of silica, titania, alumina, strontium titanate, and the like. In particular, from the viewpoint of stress resistance, it is preferable to add large particle size silica having a number average primary particle size in the range of about 80 to 500 nm. If necessary, these inorganic fine particles may be subjected to a hydrophobic treatment.

[0175] As the organic fine particles, spherical organic fine particles having a number average primary particle size in the range of about 10 to 2000 nm can be used. Specifically, organic fine particles made of homopolymers such as styrene and methyl methacrylate, or copolymers thereof can be used.

[0176] Lubricants are used to further improve cleaning properties and transfer properties, particularly to obtain the effects of the present invention. Examples of lubricants include metal salts of higher fatty acids such as salts of stearic acid with zinc, aluminum, copper, magnesium, calcium, etc., salts of oleic acid with zinc, manganese, iron, copper, magnesium, etc., salts of palmitic acid with zinc, copper, magnesium, etc., salts of linoleic acid with zinc, calcium, etc., and salts of ricinoleic acid with zinc, calcium, etc.

[0177] The fatty acid metal salt is preferably zinc stearate from the viewpoint of improving the lubricity of the surface. Zinc stearate has a moderate negative chargeability and a moderate affinity with the electron-accepting resin. Furthermore, the spacing between the layered crystals, determined by the alkyl chain length, is appropriate, and the cleavage and spreadability are good, further improving the lubricity of the surface. These external additives may be used in combination with various other additives.

[0178] The amount of the external additive added is preferably within a range of 0.1 to 10.0% by mass relative to 100% by mass of the toner base particles.

[0179] The amount of the fatty acid metal salt added is preferably within a range of 0.20 to 0.30% by mass relative to the toner base particles in order to sufficiently improve the surface lubricity, and more preferably 0.2% by mass or more. If the amount of the fatty acid metal salt added is within the range of 0.20 to 0.30% by mass relative to the toner base particles, the spreading effect is sufficient, but the coverage rate of the fatty acid metal salt does not decrease, and the surface lubricity can be sufficiently improved.

[0180] 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, in order to reliably prevent the occurrence of toner filming.

[0181] If the particle size of the fatty acid metal salt is small, it can be applied more uniformly and the lubricity of the surface can be improved. From the above viewpoint, the particle size is preferably 4 μm or less, and more preferably 2 μm or less.

[0182] 5. Image forming equipment The image forming apparatus used in the electrophotographic image forming system of the present invention is preferably an image forming apparatus using a general electrophotographic method, and preferably includes at least an electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit, a transfer unit, a fixing unit, and a cleaning unit. In particular, it is preferable that the image forming apparatus used is a tandem type image forming apparatus.

[0183] FIG. 6 is an explanatory cross-sectional view showing an example of the configuration of an image forming apparatus of the present invention, and FIG. 7 is an explanatory cross-sectional view showing an example of the configuration of a main part of the image forming apparatus. As shown in FIG. 6, this image forming apparatus 100 is called a tandem color image forming apparatus, and has four sets of image forming units 110Y, 110M, 110C, and 110Bk, paper feeding and conveying means 150, and fixing means 170. An original image reading device SC is disposed on the upper part of the main body of the image forming apparatus 100.

[0184] The image forming units 110Y, 110M, 110C, and 110Bk are arranged side by side in the vertical direction. The image forming units 110Y, 110M, 110C, and 110Bk each include a rotating drum-shaped photosensitive member 111Y, 111M, 111C, and 111Bk, and, arranged sequentially in the direction of rotation of the photosensitive member on the outer circumferential surface area thereof, a lubricant supply means, 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. Then, toner images of yellow (Y), magenta (M), cyan (C) and black (Bk) are formed on the photoreceptors 111Y, 111M, 111C and 111Bk, respectively.

[0185] Image forming units 110Y, 110M, 110C, and 110Bk are configured similarly except for the colors of the toner images formed on photoreceptors 111Y, 111M, 111C, and 111Bk, and therefore will be described below using image forming unit 110Y as an example. The electrophotographic photosensitive member, charging means, exposure means, developing means, transfer means, fixing means and cleaning means will be explained in this order.

[0186] (5.1) Charging means As shown in FIG. 7, the charging means 113Y is a means for charging the surface of the photosensitive member 111Y by means of a charging roller. The charging means 113Y in this example comprises a charging roller disposed in contact with the surface of the photosensitive member 111Y, and a power source for applying a voltage to the charging roller.

[0187] In the present invention, the charging means is of a proximity charging type, in which a charging roller is brought into contact with or in proximity to the surface of the photosensitive member and charged.

[0188] As shown in FIG. 8, the charging roller 11 is configured such that an elastic layer 11b is laminated on the surface of a core metal 11a, the elastic layer 11b reducing charging noise and imparting elasticity to obtain uniform adhesion to the photosensitive member 111Y, and a resistance control layer 11c is laminated on the surface of the elastic layer 11b as needed to obtain a highly uniform electrical resistance for the charging roller 11 as a whole, and a surface layer 11d is laminated on the resistance control layer 11c, and this layer is urged toward the photosensitive member 111Y by a compression spring 11e and pressed against the surface of the photosensitive member 111Y with a predetermined pressing force, thereby forming a charging nip portion, and the charging roller 11 rotates in response to the rotation of the photosensitive member 111Y.

[0189] The core metal 11a is made of a metal such as iron, copper, stainless steel, aluminum, or nickel, or the surface of such a metal is plated to provide rust resistance and scratch resistance without impairing conductivity, and its outer diameter is, for example, within the range of 3 to 20 mm.

[0190] The elastic layer 11b is made of an elastic material such as rubber to which conductive particles such as carbon black, carbon graphite, alkali metal salts, ammonium salts, etc. are added. Specific examples of elastic materials include synthetic rubbers such as natural rubber, ethylene propylene diene methylene rubber (EPDM), styrene-butadiene rubber (SBR), silicone rubber, urethane rubber, epichlorohydrin rubber, isoprene rubber (IR), butadiene rubber (BR), nitrile-butadiene rubber (NBR), and chloroprene rubber (CR), as well as resins such as polyamide resin, polyurethane resin, silicone resin, and fluororesin, and foams such as foam sponge. The degree of elasticity can be adjusted by adding process oil, plasticizer, etc. to the elastic material.

[0191] The elastic layer 11b has a volume resistivity of 1×10 1 ~1×10 10 It is preferable that the resistance is in the range of Ω·cm. The layer thickness is preferably in the range of 500 to 5000 μm, more preferably in the range of 500 to 3000 μm. The volume resistivity of the elastic layer 11b is a value measured in accordance with JIS K6911.

[0192] The resistance control layer 11c is provided for the purpose of providing uniform electrical resistance throughout the charging roller 11, but may not be necessary. This resistance control layer 11c can be provided by coating a material having a suitable electrical conductivity or by covering it with a tube having a suitable electrical conductivity.

[0193] Specific materials constituting this resistance control layer 11c include those made of a basic material such as a resin such as polyamide resin, polyurethane resin, fluororesin, or silicone resin; or a rubber such as epichlorohydrin rubber, urethane rubber, chloroprene rubber, or acrylonitrile rubber, to which a conductive agent such as conductive fine particles made of carbon black, carbon graphite, or the like; conductive metal oxide fine particles made of conductive titanium oxide, conductive zinc oxide, conductive tin oxide, or the like; or conductive fine particles made of alkali metal salts, ammonium salts, or the like has been added.

[0194] The resistance control layer 11c has a volume resistivity of 1×10 -2 ~1×10 14 It is preferably in the range of Ω·cm, and more preferably 1×10 1 ~1×10 10 It is in the range of Ω·cm. 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 K6911.

[0195] The surface layer 11d is provided for the purposes of preventing the plasticizer in the elastic layer 11b from bleeding out onto the surface of the resulting charging roller, for the purpose of making the surface of the charging roller slippery and smooth, and for the purpose of preventing leaks even if there are defects such as pinholes on the photosensitive element 111Y, and is provided by coating the surface with a material having appropriate conductivity or by covering it with a tube having appropriate conductivity.

[0196] When the surface layer 11d is formed by coating a material, specific examples of the material include a base material such as a resin such as polyamide resin, polyurethane resin, acrylic resin, fluororesin, or silicone resin, or epichlorohydrin rubber, urethane rubber, chloroprene rubber, or acrylonitrile rubber to which a conductive agent such as conductive fine particles made of carbon black, carbon graphite, or conductive metal oxide fine particles made of conductive titanium oxide, conductive zinc oxide, or conductive tin oxide has been added. Examples of the coating method include dip coating, roll coating, and spray coating.

[0197] Furthermore, when the surface layer 11d is provided by covering with a tube, specific examples of the tube include nylon 12, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin (PFA), polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer resin (FEP), thermoplastic elastomers such as polystyrene-based, polyolefin-based, polyvinyl chloride-based, polyurethane-based, polyester-based, and polyamide-based thermoplastic elastomers to which the above-mentioned conductive agents have been added, and which have been molded into a tube shape. The tubing may be heat shrinkable or non-heat shrinkable.

[0198] The surface layer 11d has a volume resistivity of 1×10 1 ~1×10 8 It is preferably in the range of Ω·cm, and more preferably 1×10 1 ~1×10 5 Ω·cm. 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 K6911.

[0199] 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.

[0200] In the charging roller 11 as described above, a charging bias voltage is applied to the core metal 11a of the charging roller 11 from the power source S1, whereby the surface of the photosensitive member 111Y is charged to a predetermined potential of 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, as this provides excellent charging uniformity. The charging bias voltage can be set within the range of, for example, about −2.5 to −1.5 kV.

[0201] An example of the charging conditions using the charging roller shown in Figure 8 is as follows: the charging bias voltage is formed by a DC voltage of -500 V, and the AC voltage is a sine wave with a frequency of 1000 Hz and a peak-to-peak voltage of 1300 V. When this charging bias voltage is applied, the surface of the photosensitive member is uniformly charged to -500 V.

[0202] (5.2) Exposure means As shown in FIG. 6, the exposure means 115Y is a means for exposing the surface of the photosensitive member 111Y, which has been given a uniform potential by the charging means 113Y, based on an image signal (yellow image signal), to form an electrostatic latent image corresponding to the yellow image. The exposure means 115Y is composed of an LED in which light emitting elements are arranged in an array in the axial direction of the photosensitive member 111Y and an imaging element, or a laser optical system or the like is used.

[0203] (5.3) Developing means As shown in FIG. 6, the developing means (developing machine) 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. Specifically, the developing means 117Y in this example is composed of a developing roller 118Y that has a built-in magnet and rotates while holding developer, and a voltage application device (not shown) that applies DC and / or AC bias voltage between the photosensitive element 111Y and the developing roller 118Y. The developing means 117Y is preferably disposed at the most downstream position in the rotation direction of the photosensitive member, since toner filming is likely to occur at the most downstream position.

[0204] The rotation of the developing roller 118Y transports the toner to the photoreceptor 111Y. Then, the thin layer of toner on the developing roller 118Y comes into contact with the photosensitive member 111Y and develops the electrostatic latent image on the photosensitive member 111Y. The developing roller 118Y is connected to a voltage application device. Then, a DC and / or AC bias voltage is applied to the developing roller 118Y by this voltage application device. By controlling the voltage applied to the developing roller 118Y, the developing potential (also called developing bias) (Vdc) can be adjusted to a desired value. Due to the potential difference (development potential difference) between the potential of the electrostatic latent image carried by the developing roller 118Y and the photosensitive member 111Y, an electric field is formed in the developing section where the developing roller 118Y and the photosensitive member 111Y face each other.

[0205] The toner in the developer transported to the developing unit by the rotation of the developing roller 118Y moves due to the force of the electric field and is attracted to the electrostatic latent image on the photoreceptor 111Y. When the electrostatic latent image carried on the photoreceptor 111Y is visualized, a toner image corresponding to the shape of the electrostatic latent image is formed on the surface of the photoreceptor 111Y.

[0206] Here, the electrostatic latent image on the photosensitive member includes a non-image portion and an image portion. The non-image portion is a portion of the surface of the photosensitive member 111Y that is uniformly charged by the charging roller 113Y, and the non-image portion potential (V0) is the potential of this non-image portion. The image area is a portion of the surface of the photoconductor 111Y where the potential has decreased due to a part of the non-image area being exposed by the exposure means, and 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 portion potential (V0) and the image portion potential (Vi). In the non-image area, an electric field is formed in a direction that moves the toner from the photosensitive member toward the developing means. In the image area, an electric field is formed in a direction that moves the toner from the developing means side toward the photosensitive member.

[0207] In the present invention, the development conditions of the developing machine under a normal temperature and humidity environment of 23°C and 50% RH are set to any one of the conditions (i) to (iii) above, compared to a low temperature and low humidity environment of 10°C and 20% RH. (i) Decrease the AC duty ratio (the ratio of the negative side width (time) T(-) of the AC in the cycle T) of the development potential applied to the development roller of the developing machine. (ii) Decreasing the concentration of the toner for the two-component developer in the two-component developer (iii) Increase the fogging margin (potential V0 of the non-image area of ​​the photoconductor minus development potential Vdc)

[0208] Therefore, for example, when condition (i) is set, the voltage application device of the developing means applies a voltage so as to lower the AC duty ratio of the AC and DC superimposed on the developing roller. Furthermore, when condition (iii) is set, the absolute value of Vc applied to the core of the charging roller is set high as a result. Furthermore, when the condition (ii) is set, the two-component developer used is a developer with a low toner concentration.

[0209] (5.4) Transfer means As shown in FIG. 6, a primary transfer roller 133Y constituting a transfer means is a means for transferring a toner image formed on a photosensitive member 111Y onto an intermediate transfer member 131 in the form of an endless belt. The primary transfer roller 133Y is disposed in contact with the intermediate transfer body 131.

[0210] In this image forming apparatus 100, an intermediate transfer method is adopted in which toner images formed on photosensitive bodies 111Y, 111M, 111C, and 111Bk are transferred to intermediate transfer body 131 by primary transfer rollers (primary transfer means) 133Y, 133M, 133C, and 133Bk, and each toner image transferred onto intermediate transfer body 131 is transferred to transfer material P by secondary transfer roller (secondary transfer means) 217, but a direct transfer method may also be adopted in which toner images formed on the photosensitive bodies are transferred directly to the transfer material by transfer means.

[0211] (5.5) Cleaning means As shown in FIG. 7, the cleaning means 119Y is a means for removing toner remaining on the surface of the photoreceptor 111Y. The cleaning means 119Y in this example is composed of a cleaning blade. The details of the cleaning blade according to the present invention used as the above cleaning means are as described above, and will be explained here with reference to FIGS. 6 and 7. FIG. This cleaning blade is composed of a support member and a blade member supported on this support member via an adhesive layer (not shown). The blade member is disposed so that its tip faces in the opposite direction (counter direction) to the rotation direction of the photosensitive member 111Y at the contact portion with the surface of the photosensitive member 111Y.

[0212] The support member is not particularly limited, and any conventionally known member can be used, including, for example, those made of rigid metal, elastic metal, plastic, ceramic, etc. Among these, rigid metal is preferred.

[0213] The blade member is preferably made of polyurethane. Examples of polyurethane include those obtained by reacting a polyol, a polyisocyanate, and, if necessary, a crosslinking agent. It may have a single layer structure, or may have a multi-layer structure in which a base layer and an edge layer are laminated.

[0214] As shown in FIG. 6, the intermediate transfer body 131 is wound around a plurality of rollers 137A, 137B, 137C, and 137D and is rotatably supported. Above the intermediate transfer body 131, a cleaning means 135 is disposed to remove toner remaining on the intermediate transfer body.

[0215] In this image forming apparatus 100, the photosensitive member 111Y, developing means 117Y, cleaning means 119Y, etc. may be integrally combined and may be a process cartridge (image forming unit) configured to be detachably attached to the main body of the apparatus. Alternatively, it may be a process cartridge (image forming unit) in which the photosensitive member 111Y is integrally configured with one or more members selected from the group consisting of the charging means 113Y, the exposure means 115Y, the developing means 117Y, the primary transfer roller 133Y, and the cleaning means 119Y.

[0216] The process cartridge 200 has a housing 201, and a photosensitive member 111Y, a charging unit 113Y, a developing unit 117Y, a cleaning unit 119Y, and a primary transfer roller 133Y housed therein. The apparatus main body is also provided with support rails 203L and 203R as means for guiding the process cartridge 200 into the apparatus main body. This allows the process cartridge 200 to be detachably mounted to the main body of the apparatus. These process cartridges 200 can serve as a single image forming unit that is detachably mounted on the main body of the apparatus.

[0217] The paper feed conveying means 150 is provided so as to be able to convey the transfer material P in the paper feed cassette 211 to the secondary transfer roller 217 via a plurality of intermediate rollers 213A, 213B, 213C, 213D and a registration roller 215.

[0218] The fixing means 170 fixes the color image transferred by the secondary transfer roller 217. The paper discharge rollers 219 are provided so as to be able to place the transfer material P on a paper discharge tray 221 while nipping the transfer material P that has been subjected to the fixing process.

[0219] In the image forming apparatus 100 configured as above, toner images are formed by the image forming units 110Y, 110M, 110C, and 110Bk. Specifically, first, the surfaces of the photoconductors 111Y, 111M, 111C, and 111Bk are discharged and negatively charged by the charging means 113Y, 113M, 113C, and 113Bk. Next, the surfaces of the photosensitive members 111Y, 111M, 111C, and 111Bk are exposed to light by exposure means 115Y, 115M, 115C, and 115Bk based on image signals, thereby forming electrostatic latent images. Next, developing means 117Y, 117M, 117C, and 117Bk apply toner to the surfaces of the photoreceptors 111Y, 111M, 111C, and 111Bk to develop the toner images.

[0220] Next, primary transfer rollers (primary transfer means) 133Y, 133M, 133C, and 133Bk are brought into contact with the intermediate transfer body 131 which is rotating. As a result, the toner images of each color formed on the photosensitive members 111Y, 111M, 111C, and 111Bk are transferred successively onto the rotating intermediate transfer member 131, thereby transferring a color image (primary transfer). During the image forming process, the primary transfer roller 133Bk is always in contact with the photosensitive member 111Bk. On the other hand, the other primary transfer rollers 133Y, 133M, and 133C come into contact with the corresponding photoconductors 111Y, 111M, and 111C only during color image formation.

[0221] Then, after the primary transfer rollers 133Y, 133M, 133C, and 133Bk are separated from the intermediate transfer body 131, the toner remaining on the surfaces of the photosensitive bodies 111Y, 111M, 111C, and 111Bk is removed by cleaning means 119Y, 119M, 119C, and 119Bk. Next, the surfaces of the photoconductors 111Y, 111M, 111C, and 111Bk are neutralized by neutralizing means (not shown) as necessary, and then negatively charged by charging means 113Y, 113M, 113C, and 113Bk.

[0222] Meanwhile, a transfer material P (a support material carrying the final image, such as plain paper or a transparent sheet) contained in a paper feed cassette 211 is fed by a paper feed conveying means 150 and conveyed to a secondary transfer roller (secondary transfer means) 217 ​​via multiple intermediate rollers 213A, 213B, 213C, 213D and a resist roller 215. Then, the secondary transfer roller 217 is brought into contact with the rotating intermediate transfer body 131, and the color images are 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 secondary transfer onto the transfer material P. After that, the transfer material P onto which the color image has been collectively transferred is separated at a portion of the intermediate transfer body 131 where the curvature is high.

[0223] The transfer material P onto which the color images have been transferred all at once in this way is subjected to a fixing process by fixing means 170, and then is nipped by paper discharge rollers 219 and placed on a paper discharge tray 221 outside the apparatus. After the transfer material P onto which the color image has been collectively transferred is separated from the intermediate transfer body 131, the cleaning means 135 removes the remaining toner on the intermediate transfer body 131. [Example]

[0224] Specific examples of the present invention will be described below together with comparative examples, but the present invention is not limited to these. In the examples, "parts" and "%" mean "parts by mass" and "% by mass" unless otherwise specified.

[0225] [Preparation of electrophotographic photoreceptor and confirmation of electron-accepting property] [Preparation of Electrophotographic Photoreceptor 1] An electrophotographic photoreceptor 1 was prepared as follows.

[0226] <Preparation of conductive support> The surface of a cylindrical aluminum support having a diameter of 30 mm was machined to prepare a conductive support having a surface roughness Rz=1.5 (μm).

[0227] <Formation of the intermediate layer> The following components were dispersed batchwise using a sand mill for 10 hours to obtain a dispersion.

[0228] (composition) Binder resin: Polyamide resin CM8000 (manufactured by Toray Industries, Inc.) 1 part by weight Conductive particles: Titanium oxide SMT500SAS (manufactured by Teika Co., Ltd.) 3 parts by mass Methanol 10 parts by mass

[0229] Thereafter, the dispersion was diluted two-fold with methanol and allowed to stand overnight. After being left to stand, the dispersion was filtered (using a filter: Rigimesh 5 μm filter manufactured by Nippon Pall Corporation) to obtain an intermediate layer composition. The intermediate layer composition was applied onto the conductive support by dip coating and then solidified. The dry thickness of the intermediate layer was 2 μm.

[0230] <Formation of photosensitive layer> As the photosensitive layer, the following charge generating layer and charge transport layer were formed.

[0231] (1) Formation of the charge generation layer The following components were mixed and dispersed for 10 hours using a sand mill to prepare a charge generating layer composition.

[0232] (composition) Charge-generating material: titanyl phthalocyanine pigment (a titanyl phthalocyanine pigment having a maximum diffraction peak at at least 27.3° in Cu-Kα characteristic X-ray diffraction spectrum measurement) 20 parts by mass Binder resin: Polyvinyl butyral resin (#6000-C: manufactured by Denki Kagaku Kogyo Co., Ltd.) 10 parts by mass t-Butyl acetate 700 parts by mass 4-Methoxy-4-methyl-2-pentanone 300 parts by mass

[0233] The charge generating layer composition was applied onto the intermediate layer by dip coating and then solidified. The dry thickness of the charge generating layer (also referred to as "dry film thickness") was 0.3 μm.

[0234] (2) Formation of the charge transport layer The following components were mixed to prepare a charge transport layer composition.

[0235] (composition) Charge transport material (CTM-1, having the structure represented by the following chemical formula) 150 parts by mass Binder resin: Polycarbonate (Z-300, manufactured by Mitsubishi Gas Chemical Company, Inc.) 300 parts by mass Antioxidant: Irganox 1010 (manufactured by BASF Japan) 6 parts by mass Tetrahydrofuran 1600 parts by mass Toluene 400 parts by mass Silicone oil: KF-54 (Shin-Etsu Chemical Co., Ltd.) 1 part by mass

[0236] [ka]

[0237] The charge transport layer composition was applied onto the charge generation layer by dip coating and allowed to solidify. The dry thickness of the charge transport layer was 25 μm.

[0238] <Formation of surface layer> The following components were mixed to prepare a surface layer composition.

[0239] (composition) Charge transport material (compound CTM-1 represented by the above chemical formula) 150 parts by weight Thermoplastic resin: 300 parts by mass of fluorine-containing solvent-soluble polyimide resin A1 (Sixef-44, manufactured by Hoechst Celanese) Antioxidant: Irganox 1010 (manufactured by BASF Japan) 6 parts by mass Tetrahydrofuran (boiling point 66°C) 2000 parts by mass Silicone oil: KF-54 (Shin-Etsu Chemical Co., Ltd.) 1 part by mass

[0240] The surface layer composition was applied onto the charge generating layer by dip coating and then solidified. The dry thickness of the surface layer was 10 μm. The surface layer A1 was formed by the above procedure.

[0241] [Confirmation of electron-accepting properties] <Observation of optical absorption spectrum using reference material A> A thermoplastic resin and an electron donor (reference substance A) with a known HOMO level were mixed in a mass ratio of 2:1, and the mixture was dissolved in tetrahydrofuran, and the optical absorption spectrum was measured using a spectrophotometer. On the other hand, the optical absorption spectrum of the electron donor (reference substance A) dissolved in the solvent alone was measured using a spectrophotometer. When the optical absorption spectra of these materials were compared, an absorption band at the absorption edge of 620 nm was observed in the mixture containing the thermoplastic resin. Therefore, since a new absorption band was observed in the wavelength region of 340 nm or more, it was determined that the thermoplastic resin has electron-accepting properties.

[0242] <Observation of optical absorption spectrum using reference material B> In the observation of the optical absorption spectrum using the above-mentioned reference material A, the optical absorption spectrum was measured using the same procedure but with reference material B instead of reference material A. When the spectra were compared, an absorption band above the absorption edge of 480 nm was observed in the mixture containing the thermoplastic resin. Therefore, since a new absorption band was observed in the wavelength region of 370 nm or more, it was determined that the thermoplastic resin has electron-accepting properties. An electrophotographic photoreceptor 1 was produced by the above procedure.

[0243] [Preparation of Electrophotographic Photoreceptor 2] An electrophotographic photoreceptor 2 was produced in the same manner as the electrophotographic photoreceptor 1, except that in the preparation of the surface layer composition in <Formation of Surface Layer>, the thermoplastic resin was changed to polyimide resin A2 (KPI-MX300F, manufactured by Kawamura Sangyo Co., Ltd.) to form the surface layer A2.

[0244] [Confirmation of electron-accepting properties] In addition, the presence or absence of electron-accepting properties was determined using the same procedure when observing the optical absorption spectra using reference materials A and B, and it was determined that the thermoplastic resin had electron-accepting properties in both cases.

[0245] [Preparation of Electrophotographic Photoreceptor 3] An electrophotographic photoreceptor 3 was produced in the same manner as the electrophotographic photoreceptor 1, except that in the preparation of the surface layer composition in <Formation of Surface Layer>, the thermoplastic resin was changed to polyethersulfone B (Sumikaexcel PES, manufactured by Sumitomo Chemical Co., Ltd.) to form the surface layer B.

[0246] [Confirmation of electron-accepting properties] In addition, the presence or absence of electron-accepting properties was determined using the same procedure when observing the optical absorption spectra using reference materials A and B, and it was determined that the thermoplastic resin had electron-accepting properties in both cases.

[0247] [Preparation of Electrophotographic Photoreceptor 4] An electrophotographic photoreceptor 4 was produced in the same manner as the electrophotographic photoreceptor 1, except that in the preparation of the surface layer composition in <Formation of Surface Layer>, the thermoplastic resin was changed to polyimide resin A3 (PI-100, manufactured by Maruzen Petrochemical Co., Ltd.) to form the surface layer A3.

[0248] [Confirmation of electron-accepting properties] In addition, the presence or absence of electron-accepting properties was determined using the same procedure when observing the optical absorption spectra using reference materials A and B. When reference material A was used, it was determined that the thermoplastic resin had electron-accepting properties, but when reference material B was used, the thermoplastic resin did not have electron-accepting properties.

[0249] [Preparation of Electrophotographic Photoreceptor 5] An electrophotographic photoreceptor 5 was produced in the same manner as the electrophotographic photoreceptor 1, except that in the preparation of the surface layer composition in <Formation of Surface Layer>, the thermoplastic resin was changed to polyarylate resin C (M-2000H manufactured by Unitika Ltd.) to form the surface layer C.

[0250] [Confirmation of electron-accepting properties] In addition, when the excitation spectra were observed using reference materials A and B, the presence or absence of electron-accepting properties was determined using the same procedure, and it was found that the thermoplastic resin did not have electron-accepting properties when either reference material was used.

[0251] [Cleaning blade manufacturing] [Production of cleaning blade A] <Production of 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. While changing the compounding ratio, rubber sheets of rubber material A with hardness of 72° and impact resilience of 11° were produced. The above rubber hardness is a hardness value specified in JIS-A.

[0252] <Edge formation> The rubber sheet A was cut with a blade at an angle of 10° to the vertical direction to form an edge portion with an edge angle of 100°.

[0253] <Cutting and gluing of cleaning blades> The blade was then cut vertically to a size of 340 mm x 14.0 mm, and the blade was heat-bonded to a metal plate with a 4 mm adhesive margin using a thermosetting adhesive to produce cleaning blade A with a free length of 10.0 mm.

[0254] [Preparation of cleaning blade B] In <Formation of Edge Portion>, the cleaning blade was produced in the same manner as cleaning blade A, except that the edge angle was changed to 105°.

[0255] [Fabrication of cleaning blade C] In <Preparation of Rubber Material Rubber Sheet>, the same procedure as for cleaning blade A was repeated except that a rubber material B rubber sheet having a hardness of 77° and a resilience of 15° was prepared.

[0256] [Fabrication of Cleaning Blade D] In <Formation of Edge Portion>, the blade was produced in the same manner as cleaning blade A, except that the edge angle was changed to 110°.

[0257] [Fabrication of Cleaning Blade E] In <Formation of Edge Portion>, the cleaning blade was produced in the same manner as cleaning blade A, except that the edge angle was changed to 116°.

[0258] [Fabrication of Cleaning Blade F] In <Formation of Edge Portion>, the cleaning blade was produced in the same manner as cleaning blade A, except that the edge angle was changed to 90°.

[0259] [Fabrication of cleaning blade G] In <Formation of Edge Portion>, the cleaning blade was produced in the same manner as cleaning blade A, except that the edge angle was changed to 95°.

[0260] [Fabrication of cleaning blade H] In <Formation of Edge Portion>, the cleaning blade was produced in the same manner as cleaning blade A, except that the edge angle was changed to 85°.

[0261] [Fabrication of Cleaning Blade I] In <Formation of Edge Portion>, the cleaning blade was produced in the same manner as cleaning blade A, except that the edge angle was changed to 135°.

[0262] [Toner manufacturing] <Synthesis of hybrid crystalline polyester resin (c1)> The raw material monomers for the following addition polymerization resin (styrene-acrylic resin: StAc) unit containing a bireactive monomer and a radical polymerization initiator were placed in a dropping funnel. Styrene 34 parts by mass n-Butyl acrylate 12 parts by mass Acrylic acid 2 parts by mass Polymerization initiator: di-t-butyl peroxide 7 parts by mass

[0263] Furthermore, the raw material monomers for the polycondensation resin (crystalline polyester resin: CPEs) unit shown below were placed in a four-neck flask equipped with a nitrogen inlet tube, a dehydration tube, a stirrer, and a thermocouple, and heated to 170°C to dissolve. Sebacic acid 369 parts by mass 1,10-Decanediol 318 parts by mass

[0264] Next, raw material monomers for the addition polymerization resin (StAc) were added dropwise over 90 minutes while stirring, and after aging for 60 minutes, unreacted addition polymerization monomers were removed under reduced pressure (8 kPa). The amount of the monomer removed at this time was extremely small compared to the ratio of the raw material monomers of the resin. Thereafter, 0.8 parts by mass of Ti(OBu)4 was added as an esterification catalyst, the temperature was raised to 235°C, and the reaction was carried out at normal pressure (101.3 kPa) for 5 hours and then under reduced pressure (8 kPa) for 1 hour.

[0265] 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 (c1). The hybrid crystalline polyester resin (c1) contained 8 mass % of resin (StAc) units other than CPEs (crystalline polyester resin) relative to the total mass of the resin, and was a resin in which CPEs were grafted to StAc. The hybrid crystalline polyester resin (c1) had a number average molecular weight (Mn) of 9000 and a melting point (Tc) of 76°C.

[0266] <Preparation of Aqueous Dispersion of Hybrid Crystalline Polyester Resin Particles (C1)> 30 parts by mass of the crystalline polyester resin was melted and transferred in the molten state to an emulsifying and dispersing machine "Cavitron CD1010" (manufactured by Eurotech Co., Ltd.) at a transfer rate of 100 parts by mass per minute. Simultaneously with the transfer of this molten crystalline polyester resin, dilute ammonia water with a concentration of 0.37% by mass, which was prepared by diluting 70 parts by mass of reagent ammonia water with ion-exchanged water in an aqueous solvent tank, was transferred to the emulsifying and dispersing machine "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. Then, this emulsifying and dispersing machine "Cavitron CD1010" (manufactured by Eurotech Co., Ltd.) was operated at a rotor rotation speed of 60 Hz and a pressure of 5 kg / cm. 2 By operating under the above conditions, a dispersion of fine particles of a crystalline polyester resin with a solid content of 30 parts by mass was prepared. At this time, the particles contained in the crystalline polyester resin particle dispersion had a volume-based median diameter of 200 nm.

[0267] <Preparation of Aqueous Dispersion of Amorphous Resin Particles (X1)> (First stage polymerization) A 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen introducing device was charged with 8 parts by mass of sodium dodecyl sulfate and 3,000 parts by mass of ion-exchanged water, and the internal temperature was raised to 80° C. while stirring at a stirring speed of 230 rpm under a nitrogen stream. After the temperature was raised, a solution of 10 parts by mass of potassium persulfate in 200 parts by mass of ion-exchanged water was added, and the liquid temperature was again raised to 80° C. Styrene 480 parts by mass n-Butyl acrylate 250 parts by mass Methacrylic acid 68.0 parts by mass The monomer mixture liquid consisting of the above was added dropwise over 1 hour, and then the mixture was heated at 80° C. for 2 hours with stirring to carry out polymerization, thereby preparing a dispersion liquid (x1) of resin fine particles.

[0268] (Second stage polymerization) A 5 L reaction vessel equipped with a stirrer, a temperature sensor, a cooling pipe, and a nitrogen introducing device was charged with a solution of 7 parts by mass of sodium polyoxyethylene (2) dodecyl ether sulfate dissolved in 3,000 parts by mass of ion-exchanged water, heated to 98 ° C, and then mixed with 260 parts by mass of a dispersion of resin fine particles (x1), 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: behenic acid behenate (melting point 73°C) 190 parts by mass A solution of the monomer and release agent dissolved at 90°C was added, and the mixture was 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 emulsified particles (oil droplets). Next, an initiator solution in which 6 parts by mass of potassium persulfate was dissolved in 200 parts by mass of ion-exchanged water was added to this dispersion, and the system was heated and stirred at 84°C for 1 hour to carry out polymerization, thereby preparing a dispersion of resin microparticles (x2).

[0269] (Third stage polymerization) Further, 400 parts by mass of ion-exchanged water was added to the dispersion liquid (x2) of resin fine particles and mixed well, and then a solution in which 11 parts by mass of potassium persulfate was dissolved in 400 parts by mass of ion-exchanged water was added, and the mixture was stirred at a temperature of 82°C. 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 After the dropwise addition, polymerization was carried out by heating and stirring for 2 hours, and then the mixture was cooled to 28°C to prepare an aqueous dispersion (X1) of amorphous resin particles made of vinyl resin. The resulting aqueous dispersion (X1) of amorphous resin particles had a volume-based median diameter of 220 nm, a glass transition temperature (Tg) of 55°C, and a weight-average molecular weight (Mw) of 32,000.

[0270] <Preparation of aqueous dispersion of colorant particles (Cy1)> 90 parts by mass of sodium dodecyl sulfate was added to 1600 parts by mass of ion-exchanged water. While stirring this solution, 420 parts by mass of copper phthalocyanine (CI Pigment Blue 15:3) was gradually added, followed by dispersion treatment using a stirring device "Clearmix" (manufactured by M Technique Co., Ltd.) to prepare an aqueous dispersion of colorant particles (Cy1). The resulting aqueous dispersion (Cy1) of colorant particles had a volume-based median particle diameter of 110 nm.

[0271] <Production of Cyan Toner 1> A reaction vessel equipped with a stirrer, a temperature sensor, and a cooling tube was charged with 288 parts by mass (solid content equivalent) of an aqueous dispersion of amorphous resin microparticles (X1), 70 parts by mass (solid content equivalent) of an aqueous dispersion of hybrid crystalline polyester resin microparticles (C1), and 2,000 parts by mass of ion-exchanged water, and then a 5 mol / L aqueous sodium hydroxide solution was added to adjust the pH to 10. Then, 30 parts by mass (solids equivalent) of an aqueous dispersion of colorant particles (Cy1) was added, and then an aqueous solution of 60 parts by mass of magnesium chloride dissolved in 60 parts by mass of ion-exchanged water was added over 10 minutes at 30°C while stirring. After that, the system was left to stand for 3 minutes, and then the temperature was increased to 80°C over 60 minutes, and the particle growth reaction was continued while the temperature was maintained at 80°C. In this state, the particle size of the associated particles was measured using a Coulter Multisizer 3 (manufactured by Coulter-Beckman), and 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 ion-exchanged water was added to stop particle growth. The temperature was further increased and the particles were heated and stirred at 90°C to promote particle fusion. When the average circularity of the toner reached 0.945 (HPF detection count: 4,000 particles) using an "FPIA-2100" (Sysmex Corporation) measuring device, the particles were cooled to 30°C at a cooling rate of 2.5°C / min. Next, the toner cake was subjected to solid-liquid separation, and the dehydrated toner cake was washed by repeating the process of re-dispersing the toner cake in ion-exchanged water and separating the solid from the liquid three times. After that, the toner cake was dried at 40°C for 24 hours to obtain toner base particles 1.

[0272] To 100 parts by mass of the obtained toner base particles 1, 0.6 parts by mass of hydrophobic silica (number average primary particle size = 12 nm, hydrophobicity = 68), 1.0 part by mass of hydrophobic titanium oxide (number average primary particle size = 20 nm, hydrophobicity = 63), and 0.30 parts by mass of zinc stearate as a fatty acid metal salt were added, and the mixture was mixed in a "Henschel Mixer" (manufactured by Mitsui Miike Chemical Engineering Co., Ltd.) at a rotor peripheral speed of 35 mm / sec and 32°C for 20 minutes. After that, an external additive treatment was performed to remove coarse particles using a sieve with 45 μm openings, thereby obtaining cyan toner 1 with a volume average particle size of 6.1 μm.

[0273] <Production of Cyan Toner 2> Cyan toner 2 was obtained in the same manner as in the production of cyan toner 1, except that 0.30 parts by mass of calcium stearate was added as the fatty acid metal salt.

[0274] <Production of Cyan Toner 3> Cyan toner 3 was obtained in the same manner as in the production of cyan toner 1, except that 0.15 parts by mass of zinc stearate was added as the fatty acid metal salt.

[0275] <Production of Cyan Toner 4> Cyan toner 4 was obtained in the same manner as in the production of cyan toner 1, except that 0.20 parts by mass of zinc stearate was added as the fatty acid metal salt.

[0276] [Manufacturing of developer] A ferrite carrier coated with an acrylic resin and having a volume average particle size of 60 μm was added to each of the cyan toners 1 to 4 and mixed so that the toner concentration in the developer was 6.5 mass %, thereby producing each of the developers.

[0277] [Examples 1 to 17 and Comparative Examples 1 to 3] In a bizhub C650i machine (manufactured by Konica Minolta), the drum unit was disassembled, and the prepared photoconductors 1 to 5 and cleaning blades A to I were replaced, respectively. An image forming system was prepared using developers containing toners 1 to 4, with the amount of fatty acid metal salt added and the material changed as shown in Table I, and installed in the cyan position of the machine. An image chart having a cyan band-shaped solid patch with a width of 15 mm in the conveying direction and a width of 290 mm in the direction perpendicular to the conveying direction was printed on both sides of 200,000 sheets of A4 paper. A 1 cm square partition area was set on the photoreceptor as shown in FIG. 9, and the number of occurrences of toner filming within the area was counted.

[0278] [Table 1]

[0279] [evaluation] The number of toner filmings was counted in 10 square sections along the longitudinal direction of the photosensitive member, and the total number of toner filmings in the 10 sections was counted. The fewer the total number of toner filmings that occurred, the better the result, and a total number of toner filmings of 40 or less was considered to be acceptable.

[0280] (summary) As shown in Table I above, the examples using an electrophotographic photoreceptor containing a resin determined to have electron-accepting properties in the surface layer and using a cleaning blade with an edge angle in the range of 90 to 130° and an effective contact angle in the range of 7 to 20° are generally superior to the comparative examples that do not, as can be seen from the total number of filmings that occurred. Furthermore, it is clear that it is more preferable that the electron-accepting property is determined to be present when both reference substance A and reference substance B are used.

[0281] As can be seen from a comparison of Examples 1 to 4, even if the type of resin in the surface layer of the electrophotographic photosensitive member, the edge angle of the cleaning blade, the rigid body contact angle, and the hardness and rebound resilience of the rubber material are changed within the range of the present invention, the total number of filming occurrences can be suppressed to the same extent.

[0282] From Examples 1 and 5, it can be seen that the effect of the present invention is not limited to a specific type of fatty acid metal salt material.

[0283] As can be seen from the comparison between Examples 1, 6 and 7, when the fatty acid metal salt used as an external additive to the toner is zinc stearate, if the amount added is within the range of 0.20 to 0.30 parts by mass, the total number of filmings that occur can be reduced.

[0284] Although not shown in the table, when the effective contact angle was 6°, poor image quality occurred due to toner slipping through, and therefore the evaluation was discontinued. Furthermore, when the effective contact angle was 21°, blade curling occurred, and the evaluation was discontinued. As can be seen from the comparison between Example 1 and Examples 8 to 11, when the effective contact angle of the cleaning blade is within the range of 7 to 20°, the total number of filmings that occur can be reduced.

[0285] As can be seen from a comparison of Examples 1, 3, 12, 13, 16 and 17 with Comparative Examples 2 and 3, when the edge angle of the cleaning blade is within the range of 90 to 130°, the total number of filmings that occur can be reduced.

[0286] As can be seen from the comparison with Examples 1, 2 and 14, when polyimide is used as the resin for the surface layer, the total number of filmings that occur can be reduced.

[0287] As can be seen from the comparison between Example 1, Example 15 and Comparative Example 1, the total number of filmings occurring can be reduced when the surface layer has electron-accepting properties, and furthermore, the total number of filmings occurring can be reduced even more when both reference substances A and B have electron-accepting properties. [Explanation of symbols]

[0288] 11 Charging roller 11a Core metal 11b Elastic layer 11c Resistance control layer 11d surface layer 11e Compression spring 100 Image forming device 110Y, 110M, 110C, 110Bk Image forming unit 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 roller 119Y, 119M, 119C, 119Bk, 135 Cleaning means 131 Intermediate transfer body 133Y, 133M, 133C, 133Bk Primary transfer roller (transfer means) 137A, 137B, 137C, 137D Rollers 150 Paper feed and transport means 170 Fixing means 200 Process Cartridge 201 Case 203R, 203L support rails 211 Paper cassette 213A, 213B, 213C, 213D Intermediate rollers 215 Resist Roller 217 Secondary transfer roller (transfer means) 219 Paper ejection roller 221 Paper output tray S1 power supply P Transfer material SC Document Image Reader C L Cleaning blade P g sheet metal C Contact part E Edge T Toner particles M fatty acid metal salts F Force acting on toner particles from cleaning blade F N The force that presses toner particles and hard particles vertically against the surface of the photoconductor θ1 effective contact angle θ2 rigid body contact angle θ3 wedge angle θ e Edge Angle L free length d Thickness

Claims

1. forming an electrostatic latent image on at least a photoreceptor; developing the image using a toner for developing an electrostatic image; and removing the toner for developing the electrostatic image by pressing a ridge portion of a cleaning blade against the surface of the photosensitive member, the photoreceptor has a photosensitive layer and a surface layer on a conductive support, the surface layer containing at least one thermoplastic resin selected from a polyimide resin, a polyimide amide resin, a polyetherimide resin, a polyether ether ketone resin, a polysulfone resin, a polyether sulfone resin, a polyether sulfide resin, and a polycarbonate resin; the toner particles constituting the electrostatic image developing toner contain at least a fatty acid metal salt on the surface as an external additive; an edge of a cleaning blade having an edge angle in the range of 90 to 130 degrees is pressed against the surface of the photosensitive member, and an effective contact angle of the cleaning blade is in the range of 7 to 20 degrees.

2. An electrophotographic image forming system as described in Claim 1, characterized in that the edge angle is an obtuse angle of 95° or more.

3. An electrophotographic image forming system as described in claim 1 or claim 2, characterized in that the thermoplastic resin is a polyimide resin containing electron-withdrawing groups.

4. An electrophotographic image forming system as described in any one of claims 1 to 3, characterized in that the edge angle is 110° or less.

5. An electrophotographic image forming system according to claim 1, wherein the amount of the fatty acid metal salt added is within the range of 0.20 to 0.30% by mass relative to the toner base particles.

6. An electrophotographic image forming system described in any one of claims 1 to 5, characterized in that the fatty acid metal salt is zinc stearate.

7. An electrophotographic image forming system as described in any one of claims 1 to 6, characterized in that the effective contact angle is within the range of 8 to 13 degrees.

8. An electrophotographic image forming system as described in any one of claims 1 to 7, characterized in that the edge angle is in the range of 100 to 116°.

9. An electrophotographic imaging system according to claim 1, wherein the LUMO level of the thermoplastic resin is lower than 2.3 eV.

10. An electrophotographic image forming system described in any one of claims 1 to 9, characterized in that the photosensitive layer contains a charge generating material capable of generating charge and a charge transport material having charge transport properties.

11. The electrophotographic image forming system according to claim 10, wherein the surface layer has a function of protecting the photosensitive layer.

Images